<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:9e2786b2-5c41-490c-a726-053bc4a7f53c,g:89b352b6-c43c-4d87-bb5d-dfebae0b19d7-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://vcel.com/role/CONSOLIDATEDSTATEMENTSOFSHAREHOLDERSEQUITY" xlink:type="simple" xlink:href="vcel-20251231.xsd#CONSOLIDATEDSTATEMENTSOFSHAREHOLDERSEQUITY"/>
  <link:definitionLink xlink:role="http://vcel.com/role/CONSOLIDATEDSTATEMENTSOFSHAREHOLDERSEQUITY" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_077d5bc7-f4de-49d0-9231-1e8e8a4a2f55" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_d1d0f8f2-26c2-4747-b250-ad5d57306226" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_077d5bc7-f4de-49d0-9231-1e8e8a4a2f55" xlink:to="loc_us-gaap_StatementTable_d1d0f8f2-26c2-4747-b250-ad5d57306226" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_b02525ea-31ab-4f77-8ebb-f38344abe706" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_d1d0f8f2-26c2-4747-b250-ad5d57306226" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_b02525ea-31ab-4f77-8ebb-f38344abe706" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_b02525ea-31ab-4f77-8ebb-f38344abe706_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_b02525ea-31ab-4f77-8ebb-f38344abe706" xlink:to="loc_us-gaap_EquityComponentDomain_b02525ea-31ab-4f77-8ebb-f38344abe706_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_451edecf-bd77-4ace-8434-0e47c084733d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_b02525ea-31ab-4f77-8ebb-f38344abe706" xlink:to="loc_us-gaap_EquityComponentDomain_451edecf-bd77-4ace-8434-0e47c084733d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_8f28bd8d-df58-439a-960d-2258d351965d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_451edecf-bd77-4ace-8434-0e47c084733d" xlink:to="loc_us-gaap_CommonStockMember_8f28bd8d-df58-439a-960d-2258d351965d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_f151f770-d023-4854-aff0-856207ca8d19" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_451edecf-bd77-4ace-8434-0e47c084733d" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_f151f770-d023-4854-aff0-856207ca8d19" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_a473ee6f-24c2-40d8-a1b7-0ea5a36e7bb1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_451edecf-bd77-4ace-8434-0e47c084733d" xlink:to="loc_us-gaap_RetainedEarningsMember_a473ee6f-24c2-40d8-a1b7-0ea5a36e7bb1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_0a5c5d33-f9ca-4f6b-ab57-d488b11ebc2d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_077d5bc7-f4de-49d0-9231-1e8e8a4a2f55" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_0a5c5d33-f9ca-4f6b-ab57-d488b11ebc2d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_0300c25c-6658-4067-8570-7e7a87ab669a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_0a5c5d33-f9ca-4f6b-ab57-d488b11ebc2d" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_0300c25c-6658-4067-8570-7e7a87ab669a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_5d7655ef-4eaa-4fde-8705-608951520644" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_0a5c5d33-f9ca-4f6b-ab57-d488b11ebc2d" xlink:to="loc_us-gaap_StockholdersEquity_5d7655ef-4eaa-4fde-8705-608951520644" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_fbcfc610-5282-4c9a-ac58-da0fb40555d2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_0a5c5d33-f9ca-4f6b-ab57-d488b11ebc2d" xlink:to="loc_us-gaap_NetIncomeLoss_fbcfc610-5282-4c9a-ac58-da0fb40555d2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockGrantedDuringPeriodValueSharebasedCompensation_ae627964-0552-4547-84a8-3741fb5acab7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockGrantedDuringPeriodValueSharebasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_0a5c5d33-f9ca-4f6b-ab57-d488b11ebc2d" xlink:to="loc_us-gaap_StockGrantedDuringPeriodValueSharebasedCompensation_ae627964-0552-4547-84a8-3741fb5acab7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_d5ee1e32-4ebb-420d-9a5f-e0fcf20eb0b6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_0a5c5d33-f9ca-4f6b-ab57-d488b11ebc2d" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_d5ee1e32-4ebb-420d-9a5f-e0fcf20eb0b6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_f0ed325f-f749-4f76-a8ae-e084c6857691" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_0a5c5d33-f9ca-4f6b-ab57-d488b11ebc2d" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_f0ed325f-f749-4f76-a8ae-e084c6857691" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_f97a8ce1-f723-40c5-a50d-4baf4000281c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_0a5c5d33-f9ca-4f6b-ab57-d488b11ebc2d" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_f97a8ce1-f723-40c5-a50d-4baf4000281c" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_57171d60-a0df-41ee-9e72-e4b6165d36a5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_0a5c5d33-f9ca-4f6b-ab57-d488b11ebc2d" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_57171d60-a0df-41ee-9e72-e4b6165d36a5" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures_a0babe4c-8126-4904-a838-6132d722763a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_0a5c5d33-f9ca-4f6b-ab57-d488b11ebc2d" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures_a0babe4c-8126-4904-a838-6132d722763a" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_0d3f615d-6f14-4f5d-94cd-85a702ad8f04" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_0a5c5d33-f9ca-4f6b-ab57-d488b11ebc2d" xlink:to="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_0d3f615d-6f14-4f5d-94cd-85a702ad8f04" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_29db49b4-14bd-42c4-bdca-da3bfb249b0a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_0a5c5d33-f9ca-4f6b-ab57-d488b11ebc2d" xlink:to="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_29db49b4-14bd-42c4-bdca-da3bfb249b0a" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent_f69ed18b-9ae4-40df-8179-55cf683e7c7a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_0a5c5d33-f9ca-4f6b-ab57-d488b11ebc2d" xlink:to="loc_us-gaap_OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent_f69ed18b-9ae4-40df-8179-55cf683e7c7a" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_6ecf87a0-ddca-40ee-95ae-bb957a709d7c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_0ffe0d44-ae88-4b7f-a119-24eef38d1c86" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://vcel.com/role/SummaryofSignificantAccountingPoliciesDetails" xlink:type="simple" xlink:href="vcel-20251231.xsd#SummaryofSignificantAccountingPoliciesDetails"/>
  <link:definitionLink xlink:role="http://vcel.com/role/SummaryofSignificantAccountingPoliciesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_141d6d3c-dbc8-41b8-8d81-57a361387a38" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_487107c9-b771-472f-bf54-cf9d211b0bf6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_141d6d3c-dbc8-41b8-8d81-57a361387a38" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_487107c9-b771-472f-bf54-cf9d211b0bf6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_b2428466-dbf1-417c-ba82-0d28d34b4a7e" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_487107c9-b771-472f-bf54-cf9d211b0bf6" xlink:to="loc_srt_RangeAxis_b2428466-dbf1-417c-ba82-0d28d34b4a7e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_b2428466-dbf1-417c-ba82-0d28d34b4a7e_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_b2428466-dbf1-417c-ba82-0d28d34b4a7e" xlink:to="loc_srt_RangeMember_b2428466-dbf1-417c-ba82-0d28d34b4a7e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_1c01fc7a-2e7a-4221-b17e-7cd6a2e7bc58" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_b2428466-dbf1-417c-ba82-0d28d34b4a7e" xlink:to="loc_srt_RangeMember_1c01fc7a-2e7a-4221-b17e-7cd6a2e7bc58" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_a75e46b1-eecf-4d86-ac9e-460295f487bb" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_1c01fc7a-2e7a-4221-b17e-7cd6a2e7bc58" xlink:to="loc_srt_MinimumMember_a75e46b1-eecf-4d86-ac9e-460295f487bb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_053633f0-ec32-4373-a0b6-4cafbb0e1a9e" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_1c01fc7a-2e7a-4221-b17e-7cd6a2e7bc58" xlink:to="loc_srt_MaximumMember_053633f0-ec32-4373-a0b6-4cafbb0e1a9e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_bfd653a6-7733-4bcb-8f86-095ec33a78d7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_487107c9-b771-472f-bf54-cf9d211b0bf6" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_bfd653a6-7733-4bcb-8f86-095ec33a78d7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_bfd653a6-7733-4bcb-8f86-095ec33a78d7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_bfd653a6-7733-4bcb-8f86-095ec33a78d7" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_bfd653a6-7733-4bcb-8f86-095ec33a78d7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_05ea3dee-2dd2-4a86-aeed-1bffd58ad194" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_bfd653a6-7733-4bcb-8f86-095ec33a78d7" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_05ea3dee-2dd2-4a86-aeed-1bffd58ad194" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MachineryAndEquipmentMember_eaf37906-43ae-47e8-b12e-3f65a19935d3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MachineryAndEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_05ea3dee-2dd2-4a86-aeed-1bffd58ad194" xlink:to="loc_us-gaap_MachineryAndEquipmentMember_eaf37906-43ae-47e8-b12e-3f65a19935d3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FurnitureAndFixturesMember_1cb54983-9c68-4b47-81a9-f180c1e0e396" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FurnitureAndFixturesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_05ea3dee-2dd2-4a86-aeed-1bffd58ad194" xlink:to="loc_us-gaap_FurnitureAndFixturesMember_1cb54983-9c68-4b47-81a9-f180c1e0e396" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_ComputerEquipmentAndSoftwareMember_79d149d5-677e-47e0-b5de-90421d4fd5c7" xlink:href="vcel-20251231.xsd#vcel_ComputerEquipmentAndSoftwareMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_05ea3dee-2dd2-4a86-aeed-1bffd58ad194" xlink:to="loc_vcel_ComputerEquipmentAndSoftwareMember_79d149d5-677e-47e0-b5de-90421d4fd5c7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseholdImprovementsMember_5113b3ae-65ef-4b2d-9b64-43c4f3908377" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LeaseholdImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_05ea3dee-2dd2-4a86-aeed-1bffd58ad194" xlink:to="loc_us-gaap_LeaseholdImprovementsMember_5113b3ae-65ef-4b2d-9b64-43c4f3908377" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_LesseeLeaseRenewalTerm_58d590c2-0c92-4fd3-8805-d6e773244bc2" xlink:href="vcel-20251231.xsd#vcel_LesseeLeaseRenewalTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_141d6d3c-dbc8-41b8-8d81-57a361387a38" xlink:to="loc_vcel_LesseeLeaseRenewalTerm_58d590c2-0c92-4fd3-8805-d6e773244bc2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_9c0bd4b8-8667-4c6d-b143-25ea7ea117f4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_141d6d3c-dbc8-41b8-8d81-57a361387a38" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_9c0bd4b8-8667-4c6d-b143-25ea7ea117f4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_b444d471-446b-4a47-89ef-ebbb200ad731" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ImpairmentOfLongLivedAssetsHeldForUse"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_141d6d3c-dbc8-41b8-8d81-57a361387a38" xlink:to="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_b444d471-446b-4a47-89ef-ebbb200ad731" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://vcel.com/role/RevenueScheduleofdisaggregationofrevenueDetails" xlink:type="simple" xlink:href="vcel-20251231.xsd#RevenueScheduleofdisaggregationofrevenueDetails"/>
  <link:definitionLink xlink:role="http://vcel.com/role/RevenueScheduleofdisaggregationofrevenueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_91557182-0128-4823-96ec-299df7824fa3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_4c9063dc-3677-4d67-beef-b99eac4a3cef" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_91557182-0128-4823-96ec-299df7824fa3" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_4c9063dc-3677-4d67-beef-b99eac4a3cef" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelAxis_f5d8620e-1ec9-4de1-9a21-8e455db163e6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractWithCustomerSalesChannelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_4c9063dc-3677-4d67-beef-b99eac4a3cef" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelAxis_f5d8620e-1ec9-4de1-9a21-8e455db163e6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelDomain_f5d8620e-1ec9-4de1-9a21-8e455db163e6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractWithCustomerSalesChannelDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelAxis_f5d8620e-1ec9-4de1-9a21-8e455db163e6" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelDomain_f5d8620e-1ec9-4de1-9a21-8e455db163e6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelDomain_9e43cf54-2720-42bd-a8e1-b2bc0be166c9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractWithCustomerSalesChannelDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelAxis_f5d8620e-1ec9-4de1-9a21-8e455db163e6" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelDomain_9e43cf54-2720-42bd-a8e1-b2bc0be166c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SalesChannelThroughIntermediaryMember_ce247943-55e3-445e-bc5f-15b5479df4ed" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SalesChannelThroughIntermediaryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelDomain_9e43cf54-2720-42bd-a8e1-b2bc0be166c9" xlink:to="loc_us-gaap_SalesChannelThroughIntermediaryMember_ce247943-55e3-445e-bc5f-15b5479df4ed" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TimeAndMaterialsContractMember_bdcc8f16-87b5-472c-9279-f373ba23b680" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TimeAndMaterialsContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelDomain_9e43cf54-2720-42bd-a8e1-b2bc0be166c9" xlink:to="loc_us-gaap_TimeAndMaterialsContractMember_bdcc8f16-87b5-472c-9279-f373ba23b680" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_ProviderorFacilityMember_5efa12c9-698d-4589-8128-77cacc7b266b" xlink:href="vcel-20251231.xsd#vcel_ProviderorFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelDomain_9e43cf54-2720-42bd-a8e1-b2bc0be166c9" xlink:to="loc_vcel_ProviderorFacilityMember_5efa12c9-698d-4589-8128-77cacc7b266b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SalesChannelDirectlyToConsumerMember_94cf3eb6-8712-472e-9995-a28332375a52" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SalesChannelDirectlyToConsumerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelDomain_9e43cf54-2720-42bd-a8e1-b2bc0be166c9" xlink:to="loc_us-gaap_SalesChannelDirectlyToConsumerMember_94cf3eb6-8712-472e-9995-a28332375a52" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_6261de93-a187-411c-995d-413542aba539" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_4c9063dc-3677-4d67-beef-b99eac4a3cef" xlink:to="loc_srt_ProductOrServiceAxis_6261de93-a187-411c-995d-413542aba539" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_6261de93-a187-411c-995d-413542aba539_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_6261de93-a187-411c-995d-413542aba539" xlink:to="loc_srt_ProductsAndServicesDomain_6261de93-a187-411c-995d-413542aba539_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_953a142d-604f-4c49-b0a6-0482df17df76" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_6261de93-a187-411c-995d-413542aba539" xlink:to="loc_srt_ProductsAndServicesDomain_953a142d-604f-4c49-b0a6-0482df17df76" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_ImplantsMember_b082bda4-0273-4436-a3e6-afb1600e3eca" xlink:href="vcel-20251231.xsd#vcel_ImplantsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_953a142d-604f-4c49-b0a6-0482df17df76" xlink:to="loc_vcel_ImplantsMember_b082bda4-0273-4436-a3e6-afb1600e3eca" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_BiopsyKitsMember_33d81cd1-53d6-4a43-a573-73f698f869dd" xlink:href="vcel-20251231.xsd#vcel_BiopsyKitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_953a142d-604f-4c49-b0a6-0482df17df76" xlink:to="loc_vcel_BiopsyKitsMember_33d81cd1-53d6-4a43-a573-73f698f869dd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_MACIImplantsAndKitsMember_09b0b121-163f-4366-88c3-44c798f8f49c" xlink:href="vcel-20251231.xsd#vcel_MACIImplantsAndKitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_953a142d-604f-4c49-b0a6-0482df17df76" xlink:to="loc_vcel_MACIImplantsAndKitsMember_09b0b121-163f-4366-88c3-44c798f8f49c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_EpicelMember_4b84f03c-a5a7-4877-aece-625f9ca35ba7" xlink:href="vcel-20251231.xsd#vcel_EpicelMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_953a142d-604f-4c49-b0a6-0482df17df76" xlink:to="loc_vcel_EpicelMember_4b84f03c-a5a7-4877-aece-625f9ca35ba7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_NexoBridMember_6c9bf443-4845-4f91-bc8c-cf7c8c0c4cce" xlink:href="vcel-20251231.xsd#vcel_NexoBridMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_953a142d-604f-4c49-b0a6-0482df17df76" xlink:to="loc_vcel_NexoBridMember_6c9bf443-4845-4f91-bc8c-cf7c8c0c4cce" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_f85377f7-ce42-438b-a099-795dcfc1af48" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractWithCustomerBasisOfPricingAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_4c9063dc-3677-4d67-beef-b99eac4a3cef" xlink:to="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_f85377f7-ce42-438b-a099-795dcfc1af48" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_f85377f7-ce42-438b-a099-795dcfc1af48_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractWithCustomerBasisOfPricingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_f85377f7-ce42-438b-a099-795dcfc1af48" xlink:to="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_f85377f7-ce42-438b-a099-795dcfc1af48_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_74b69d96-5ce0-4a30-af61-d7f3a6e1bdac" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractWithCustomerBasisOfPricingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_f85377f7-ce42-438b-a099-795dcfc1af48" xlink:to="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_74b69d96-5ce0-4a30-af61-d7f3a6e1bdac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FixedPriceContractMember_4c0e1584-dc2c-4763-b8f4-264183204ac7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FixedPriceContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_74b69d96-5ce0-4a30-af61-d7f3a6e1bdac" xlink:to="loc_us-gaap_FixedPriceContractMember_4c0e1584-dc2c-4763-b8f4-264183204ac7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TimeAndMaterialsContractMember_58cade7c-5287-4823-ba97-002d48a57c5c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TimeAndMaterialsContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_74b69d96-5ce0-4a30-af61-d7f3a6e1bdac" xlink:to="loc_us-gaap_TimeAndMaterialsContractMember_58cade7c-5287-4823-ba97-002d48a57c5c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ChangeInAccountingEstimateByTypeAxis_2b933ab2-0079-4f8b-b9a9-e2d7d4803431" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ChangeInAccountingEstimateByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_4c9063dc-3677-4d67-beef-b99eac4a3cef" xlink:to="loc_us-gaap_ChangeInAccountingEstimateByTypeAxis_2b933ab2-0079-4f8b-b9a9-e2d7d4803431" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ChangeInAccountingEstimateTypeDomain_2b933ab2-0079-4f8b-b9a9-e2d7d4803431_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ChangeInAccountingEstimateTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ChangeInAccountingEstimateByTypeAxis_2b933ab2-0079-4f8b-b9a9-e2d7d4803431" xlink:to="loc_us-gaap_ChangeInAccountingEstimateTypeDomain_2b933ab2-0079-4f8b-b9a9-e2d7d4803431_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ChangeInAccountingEstimateTypeDomain_9a5e7c6c-667d-418f-8843-36ad43698864" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ChangeInAccountingEstimateTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ChangeInAccountingEstimateByTypeAxis_2b933ab2-0079-4f8b-b9a9-e2d7d4803431" xlink:to="loc_us-gaap_ChangeInAccountingEstimateTypeDomain_9a5e7c6c-667d-418f-8843-36ad43698864" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ChangeInAccountingMethodAccountedForAsChangeInEstimateMember_eaaac4ea-c085-4bc5-831a-bfb10604ffc0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ChangeInAccountingMethodAccountedForAsChangeInEstimateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ChangeInAccountingEstimateTypeDomain_9a5e7c6c-667d-418f-8843-36ad43698864" xlink:to="loc_us-gaap_ChangeInAccountingMethodAccountedForAsChangeInEstimateMember_eaaac4ea-c085-4bc5-831a-bfb10604ffc0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_1f6a9909-7555-47af-ab2e-d514b84be54c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_91557182-0128-4823-96ec-299df7824fa3" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_1f6a9909-7555-47af-ab2e-d514b84be54c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueNotFromContractWithCustomerOther_c20a7b01-f2aa-4bb2-9525-6fac89ae467b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueNotFromContractWithCustomerOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_91557182-0128-4823-96ec-299df7824fa3" xlink:to="loc_us-gaap_RevenueNotFromContractWithCustomerOther_c20a7b01-f2aa-4bb2-9525-6fac89ae467b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_05742b9c-aa17-4306-8cc1-898477c0f921" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_91557182-0128-4823-96ec-299df7824fa3" xlink:to="loc_us-gaap_Revenues_05742b9c-aa17-4306-8cc1-898477c0f921" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://vcel.com/role/RevenueSchedulesofconcentrationofcreditriskDetails" xlink:type="simple" xlink:href="vcel-20251231.xsd#RevenueSchedulesofconcentrationofcreditriskDetails"/>
  <link:definitionLink xlink:role="http://vcel.com/role/RevenueSchedulesofconcentrationofcreditriskDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_f745144c-6735-4ae0-9426-a64ccaf45ef5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_1d95fd95-e1b8-4302-ba53-097847104eba" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_f745144c-6735-4ae0-9426-a64ccaf45ef5" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_1d95fd95-e1b8-4302-ba53-097847104eba" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_5594b3fa-9f88-42e3-9623-68b15afe21e4" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_1d95fd95-e1b8-4302-ba53-097847104eba" xlink:to="loc_srt_MajorCustomersAxis_5594b3fa-9f88-42e3-9623-68b15afe21e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_5594b3fa-9f88-42e3-9623-68b15afe21e4_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_5594b3fa-9f88-42e3-9623-68b15afe21e4" xlink:to="loc_srt_NameOfMajorCustomerDomain_5594b3fa-9f88-42e3-9623-68b15afe21e4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_11b56a5d-42ec-49ae-bc46-0b27bb4c2880" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_5594b3fa-9f88-42e3-9623-68b15afe21e4" xlink:to="loc_srt_NameOfMajorCustomerDomain_11b56a5d-42ec-49ae-bc46-0b27bb4c2880" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_CustomerOneMember_416dcea9-217e-4fa6-876f-a56919e7c3ea" xlink:href="vcel-20251231.xsd#vcel_CustomerOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_11b56a5d-42ec-49ae-bc46-0b27bb4c2880" xlink:to="loc_vcel_CustomerOneMember_416dcea9-217e-4fa6-876f-a56919e7c3ea" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_7cf029e6-fe56-4af9-b8b3-c1f14d769dd6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_1d95fd95-e1b8-4302-ba53-097847104eba" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_7cf029e6-fe56-4af9-b8b3-c1f14d769dd6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_7cf029e6-fe56-4af9-b8b3-c1f14d769dd6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_7cf029e6-fe56-4af9-b8b3-c1f14d769dd6" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_7cf029e6-fe56-4af9-b8b3-c1f14d769dd6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_c0aa550e-08ab-46c3-bc94-cb3cef0a5056" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_7cf029e6-fe56-4af9-b8b3-c1f14d769dd6" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_c0aa550e-08ab-46c3-bc94-cb3cef0a5056" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SalesRevenueNetMember_4e80abd9-1f30-41ad-b037-430c319b349e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SalesRevenueNetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_c0aa550e-08ab-46c3-bc94-cb3cef0a5056" xlink:to="loc_us-gaap_SalesRevenueNetMember_4e80abd9-1f30-41ad-b037-430c319b349e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableMember_79016e3f-ac65-4b22-a642-03e2c4f25d10" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccountsReceivableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_c0aa550e-08ab-46c3-bc94-cb3cef0a5056" xlink:to="loc_us-gaap_AccountsReceivableMember_79016e3f-ac65-4b22-a642-03e2c4f25d10" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_9476d3c9-1f10-4b7d-a5bc-f1d516a021b8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_1d95fd95-e1b8-4302-ba53-097847104eba" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_9476d3c9-1f10-4b7d-a5bc-f1d516a021b8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_9476d3c9-1f10-4b7d-a5bc-f1d516a021b8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_9476d3c9-1f10-4b7d-a5bc-f1d516a021b8" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_9476d3c9-1f10-4b7d-a5bc-f1d516a021b8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_38997197-ffe3-47ee-92bd-e1eb185a75a0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_9476d3c9-1f10-4b7d-a5bc-f1d516a021b8" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_38997197-ffe3-47ee-92bd-e1eb185a75a0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerConcentrationRiskMember_9d4dfddf-ef25-4d22-abc5-3ac95f878a66" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CustomerConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_38997197-ffe3-47ee-92bd-e1eb185a75a0" xlink:to="loc_us-gaap_CustomerConcentrationRiskMember_9d4dfddf-ef25-4d22-abc5-3ac95f878a66" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_9ebb7131-577d-481f-b5a4-522755b2d531" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_f745144c-6735-4ae0-9426-a64ccaf45ef5" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_9ebb7131-577d-481f-b5a4-522755b2d531" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://vcel.com/role/SelectedBalanceSheetComponentsScheduleofpropertyandequipmentnetDetails" xlink:type="simple" xlink:href="vcel-20251231.xsd#SelectedBalanceSheetComponentsScheduleofpropertyandequipmentnetDetails"/>
  <link:definitionLink xlink:role="http://vcel.com/role/SelectedBalanceSheetComponentsScheduleofpropertyandequipmentnetDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_af34e6e5-451a-4a5b-be81-20a7852a7589" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_e6662721-274b-4172-a1f4-13dc7cd092ae" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_af34e6e5-451a-4a5b-be81-20a7852a7589" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_e6662721-274b-4172-a1f4-13dc7cd092ae" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_4aa8d1ea-1e15-4217-8114-8f6c48fc59e7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_e6662721-274b-4172-a1f4-13dc7cd092ae" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_4aa8d1ea-1e15-4217-8114-8f6c48fc59e7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_4aa8d1ea-1e15-4217-8114-8f6c48fc59e7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_4aa8d1ea-1e15-4217-8114-8f6c48fc59e7" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_4aa8d1ea-1e15-4217-8114-8f6c48fc59e7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_1d8c77e7-8d02-4a81-b932-721f3b4c2cc9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_4aa8d1ea-1e15-4217-8114-8f6c48fc59e7" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_1d8c77e7-8d02-4a81-b932-721f3b4c2cc9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MachineryAndEquipmentMember_35672b34-dcd0-4100-8373-41381f862368" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MachineryAndEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_1d8c77e7-8d02-4a81-b932-721f3b4c2cc9" xlink:to="loc_us-gaap_MachineryAndEquipmentMember_35672b34-dcd0-4100-8373-41381f862368" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FurnitureAndFixturesMember_792658e9-0314-4993-88d1-5d3d2a5ef2db" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FurnitureAndFixturesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_1d8c77e7-8d02-4a81-b932-721f3b4c2cc9" xlink:to="loc_us-gaap_FurnitureAndFixturesMember_792658e9-0314-4993-88d1-5d3d2a5ef2db" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_ComputerEquipmentAndSoftwareMember_019c7561-7fed-7e2a-bef0-65b8258524c5" xlink:href="vcel-20251231.xsd#vcel_ComputerEquipmentAndSoftwareMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_1d8c77e7-8d02-4a81-b932-721f3b4c2cc9" xlink:to="loc_vcel_ComputerEquipmentAndSoftwareMember_019c7561-7fed-7e2a-bef0-65b8258524c5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseholdImprovementsMember_70a4917d-e2dd-4926-aa34-d1968276f6f0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LeaseholdImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_1d8c77e7-8d02-4a81-b932-721f3b4c2cc9" xlink:to="loc_us-gaap_LeaseholdImprovementsMember_70a4917d-e2dd-4926-aa34-d1968276f6f0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConstructionInProgressMember_03335d6e-6f7e-48e2-84e8-76bd7322653e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConstructionInProgressMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_1d8c77e7-8d02-4a81-b932-721f3b4c2cc9" xlink:to="loc_us-gaap_ConstructionInProgressMember_03335d6e-6f7e-48e2-84e8-76bd7322653e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization_b8bb120c-85c8-4bbc-a8aa-e4e5b0dd70bf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_af34e6e5-451a-4a5b-be81-20a7852a7589" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization_b8bb120c-85c8-4bbc-a8aa-e4e5b0dd70bf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization_23702959-e8c3-4800-8ce6-e3607dae20c8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_af34e6e5-451a-4a5b-be81-20a7852a7589" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization_23702959-e8c3-4800-8ce6-e3607dae20c8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_dd7d0e8a-d8ac-4f9f-8ea0-6b3553885471" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_af34e6e5-451a-4a5b-be81-20a7852a7589" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_dd7d0e8a-d8ac-4f9f-8ea0-6b3553885471" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://vcel.com/role/SelectedBalanceSheetComponentsNarrativeDetails" xlink:type="simple" xlink:href="vcel-20251231.xsd#SelectedBalanceSheetComponentsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://vcel.com/role/SelectedBalanceSheetComponentsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_f2c28428-73c9-44ba-8bdc-01b81eda5be3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_981dc20f-5937-447c-b890-4518e08ab7b2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_f2c28428-73c9-44ba-8bdc-01b81eda5be3" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_981dc20f-5937-447c-b890-4518e08ab7b2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_4977d757-8255-4cea-93dc-b5b27837af7a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_981dc20f-5937-447c-b890-4518e08ab7b2" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_4977d757-8255-4cea-93dc-b5b27837af7a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_4977d757-8255-4cea-93dc-b5b27837af7a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_4977d757-8255-4cea-93dc-b5b27837af7a" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_4977d757-8255-4cea-93dc-b5b27837af7a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_02053c1e-e70a-4e8b-bafc-4a34febd5070" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_4977d757-8255-4cea-93dc-b5b27837af7a" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_02053c1e-e70a-4e8b-bafc-4a34febd5070" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LicensingAgreementsMember_560ac714-8cda-4244-8bb3-ad24b8070543" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LicensingAgreementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_02053c1e-e70a-4e8b-bafc-4a34febd5070" xlink:to="loc_us-gaap_LicensingAgreementsMember_560ac714-8cda-4244-8bb3-ad24b8070543" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_21b2b610-85d3-48f5-b6f5-e11dd7ce6544" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Depreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_f2c28428-73c9-44ba-8bdc-01b81eda5be3" xlink:to="loc_us-gaap_Depreciation_21b2b610-85d3-48f5-b6f5-e11dd7ce6544" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_3f2b7bfe-e9c2-4987-955a-fbf1cabce41d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_f2c28428-73c9-44ba-8bdc-01b81eda5be3" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_3f2b7bfe-e9c2-4987-955a-fbf1cabce41d" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://vcel.com/role/SelectedBalanceSheetComponentsScheduleoffinitelivedintangibleassetsDetails" xlink:type="simple" xlink:href="vcel-20251231.xsd#SelectedBalanceSheetComponentsScheduleoffinitelivedintangibleassetsDetails"/>
  <link:definitionLink xlink:role="http://vcel.com/role/SelectedBalanceSheetComponentsScheduleoffinitelivedintangibleassetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_24bfe19e-0970-4b00-a6db-9ce2fed3b16d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_6fc68a29-d561-4dd0-a2e4-f4cd005c0b66" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_24bfe19e-0970-4b00-a6db-9ce2fed3b16d" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_6fc68a29-d561-4dd0-a2e4-f4cd005c0b66" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_563f6a01-8171-49c5-9fce-4e3961e0ce51" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_6fc68a29-d561-4dd0-a2e4-f4cd005c0b66" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_563f6a01-8171-49c5-9fce-4e3961e0ce51" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_563f6a01-8171-49c5-9fce-4e3961e0ce51_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_563f6a01-8171-49c5-9fce-4e3961e0ce51" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_563f6a01-8171-49c5-9fce-4e3961e0ce51_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_013088d5-4501-42ed-8ff1-e0270c5b5f0c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_563f6a01-8171-49c5-9fce-4e3961e0ce51" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_013088d5-4501-42ed-8ff1-e0270c5b5f0c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LicensingAgreementsMember_44c201e2-0dd4-4781-986e-b5fe1e63a65e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LicensingAgreementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_013088d5-4501-42ed-8ff1-e0270c5b5f0c" xlink:to="loc_us-gaap_LicensingAgreementsMember_44c201e2-0dd4-4781-986e-b5fe1e63a65e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_6ef60145-4add-4acf-a8df-83d0bc69ed48" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_24bfe19e-0970-4b00-a6db-9ce2fed3b16d" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_6ef60145-4add-4acf-a8df-83d0bc69ed48" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_1106555f-d6ab-4385-bd7e-c2cdd1d5b60b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_24bfe19e-0970-4b00-a6db-9ce2fed3b16d" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_1106555f-d6ab-4385-bd7e-c2cdd1d5b60b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_6896d483-fa3e-46ac-a754-e5572402ada8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_24bfe19e-0970-4b00-a6db-9ce2fed3b16d" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_6896d483-fa3e-46ac-a754-e5572402ada8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_f6808ea6-cf20-4a5c-958e-f538e0726499" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_24bfe19e-0970-4b00-a6db-9ce2fed3b16d" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_f6808ea6-cf20-4a5c-958e-f538e0726499" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://vcel.com/role/LeasesNarrativeDetails" xlink:type="simple" xlink:href="vcel-20251231.xsd#LeasesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://vcel.com/role/LeasesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionLineItems_019b2189-8d04-7bfd-802f-0804acc2b3e8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LesseeLeaseDescriptionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionTable_019b2189-8d04-7f93-9b4f-b38020a12754" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LesseeLeaseDescriptionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019b2189-8d04-7bfd-802f-0804acc2b3e8" xlink:to="loc_us-gaap_LesseeLeaseDescriptionTable_019b2189-8d04-7f93-9b4f-b38020a12754" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis_019b2189-8d04-78b9-8acd-5a01fc5d7bc3" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_019b2189-8d04-7f93-9b4f-b38020a12754" xlink:to="loc_srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis_019b2189-8d04-78b9-8acd-5a01fc5d7bc3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain_019b2189-8d04-78b9-8acd-5a01fc5d7bc3_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis_019b2189-8d04-78b9-8acd-5a01fc5d7bc3" xlink:to="loc_srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain_019b2189-8d04-78b9-8acd-5a01fc5d7bc3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain_019b2189-8d04-75e2-8ac9-ed7e76a688b9" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis_019b2189-8d04-78b9-8acd-5a01fc5d7bc3" xlink:to="loc_srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain_019b2189-8d04-75e2-8ac9-ed7e76a688b9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_A25NetworkDriveBurlingtonMassachusettsMember_019b2189-8d04-75c6-80f4-e0b6d0808516" xlink:href="vcel-20251231.xsd#vcel_A25NetworkDriveBurlingtonMassachusettsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain_019b2189-8d04-75e2-8ac9-ed7e76a688b9" xlink:to="loc_vcel_A25NetworkDriveBurlingtonMassachusettsMember_019b2189-8d04-75c6-80f4-e0b6d0808516" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AreaOfRealEstateProperty_019b2189-8d04-7cf6-87b7-8bccaa5d6f15" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AreaOfRealEstateProperty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019b2189-8d04-7bfd-802f-0804acc2b3e8" xlink:to="loc_us-gaap_AreaOfRealEstateProperty_019b2189-8d04-7cf6-87b7-8bccaa5d6f15" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_EscrowDepositPercentContributed_019b2189-8d04-7854-aa23-f7107de07605" xlink:href="vcel-20251231.xsd#vcel_EscrowDepositPercentContributed"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019b2189-8d04-7bfd-802f-0804acc2b3e8" xlink:to="loc_vcel_EscrowDepositPercentContributed_019b2189-8d04-7854-aa23-f7107de07605" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EscrowDeposit_019b2189-8d04-73f0-96a9-82ba23a26e64" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EscrowDeposit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019b2189-8d04-7bfd-802f-0804acc2b3e8" xlink:to="loc_us-gaap_EscrowDeposit_019b2189-8d04-73f0-96a9-82ba23a26e64" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_ProceedsFromEscrowAccountRefund_019b2189-8d04-74b7-abe8-ff2b913f653f" xlink:href="vcel-20251231.xsd#vcel_ProceedsFromEscrowAccountRefund"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019b2189-8d04-7bfd-802f-0804acc2b3e8" xlink:to="loc_vcel_ProceedsFromEscrowAccountRefund_019b2189-8d04-74b7-abe8-ff2b913f653f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_019b2189-8d04-751b-8b70-b24a2525a9cb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLeaseRightOfUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019b2189-8d04-7bfd-802f-0804acc2b3e8" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_019b2189-8d04-751b-8b70-b24a2525a9cb" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermLeaseCost_019b218d-ac0f-72d7-a874-3efe893f0782" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortTermLeaseCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019b2189-8d04-7bfd-802f-0804acc2b3e8" xlink:to="loc_us-gaap_ShortTermLeaseCost_019b218d-ac0f-72d7-a874-3efe893f0782" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseExpense_019b218d-ac0f-7e31-a53e-0b505651fad7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLeaseExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019b2189-8d04-7bfd-802f-0804acc2b3e8" xlink:to="loc_us-gaap_OperatingLeaseExpense_019b218d-ac0f-7e31-a53e-0b505651fad7" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseInterestExpense_019b218d-ac0f-765e-8e55-8d321e720d2e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinanceLeaseInterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019b2189-8d04-7bfd-802f-0804acc2b3e8" xlink:to="loc_us-gaap_FinanceLeaseInterestExpense_019b218d-ac0f-765e-8e55-8d321e720d2e" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_PaymentsForMeasurementOfOperatingLeaseLiability_019b2190-0c13-7cdb-80fe-aa4431b18ddd" xlink:href="vcel-20251231.xsd#vcel_PaymentsForMeasurementOfOperatingLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019b2189-8d04-7bfd-802f-0804acc2b3e8" xlink:to="loc_vcel_PaymentsForMeasurementOfOperatingLeaseLiability_019b2190-0c13-7cdb-80fe-aa4431b18ddd" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_ProceedsFromMeasurementOfOperatingLeaseLiability_019c7567-8ab4-7db7-aae1-e067813e46af" xlink:href="vcel-20251231.xsd#vcel_ProceedsFromMeasurementOfOperatingLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019b2189-8d04-7bfd-802f-0804acc2b3e8" xlink:to="loc_vcel_ProceedsFromMeasurementOfOperatingLeaseLiability_019c7567-8ab4-7db7-aae1-e067813e46af" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_PaymentsForMeasurementOfFinanceLeaseLiability_019be025-10f5-7c24-9e33-a684291ddf0d" xlink:href="vcel-20251231.xsd#vcel_PaymentsForMeasurementOfFinanceLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_019b2189-8d04-7bfd-802f-0804acc2b3e8" xlink:to="loc_vcel_PaymentsForMeasurementOfFinanceLeaseLiability_019be025-10f5-7c24-9e33-a684291ddf0d" xlink:type="arc" order="10"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://vcel.com/role/InvestmentsScheduleofFairValueofSecuritiesNotIncludingCashDetails" xlink:type="simple" xlink:href="vcel-20251231.xsd#InvestmentsScheduleofFairValueofSecuritiesNotIncludingCashDetails"/>
  <link:definitionLink xlink:role="http://vcel.com/role/InvestmentsScheduleofFairValueofSecuritiesNotIncludingCashDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MarketableSecuritiesLineItems_6ad32856-3184-48b7-a134-51143c0acef5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MarketableSecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MarketableSecuritiesTable_bc5b540b-9dd6-48a7-9af6-dd6b6952b844" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MarketableSecuritiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_6ad32856-3184-48b7-a134-51143c0acef5" xlink:to="loc_us-gaap_MarketableSecuritiesTable_bc5b540b-9dd6-48a7-9af6-dd6b6952b844" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_d3179bc3-8213-4b3d-9513-e2ec9a8763c5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_MarketableSecuritiesTable_bc5b540b-9dd6-48a7-9af6-dd6b6952b844" xlink:to="loc_us-gaap_FinancialInstrumentAxis_d3179bc3-8213-4b3d-9513-e2ec9a8763c5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_d3179bc3-8213-4b3d-9513-e2ec9a8763c5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_d3179bc3-8213-4b3d-9513-e2ec9a8763c5" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_d3179bc3-8213-4b3d-9513-e2ec9a8763c5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_12e5d776-26d2-446c-af87-acdd09347b21" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_d3179bc3-8213-4b3d-9513-e2ec9a8763c5" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_12e5d776-26d2-446c-af87-acdd09347b21" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPaperNotIncludedWithCashAndCashEquivalentsMember_019c8b6f-0b1c-779a-ab75-73347cb27a06" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommercialPaperNotIncludedWithCashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_12e5d776-26d2-446c-af87-acdd09347b21" xlink:to="loc_us-gaap_CommercialPaperNotIncludedWithCashAndCashEquivalentsMember_019c8b6f-0b1c-779a-ab75-73347cb27a06" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNoteSecuritiesMember_0079e454-de2a-4284-8a8f-8c8369782f1a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CorporateNoteSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_12e5d776-26d2-446c-af87-acdd09347b21" xlink:to="loc_us-gaap_CorporateNoteSecuritiesMember_0079e454-de2a-4284-8a8f-8c8369782f1a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_aac8be6a-22d6-44d8-a2b9-2f99901959bb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USGovernmentAgenciesDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_12e5d776-26d2-446c-af87-acdd09347b21" xlink:to="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_aac8be6a-22d6-44d8-a2b9-2f99901959bb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_d38cd730-5b72-4c94-b03a-ed6dfb39f498" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_MarketableSecuritiesTable_bc5b540b-9dd6-48a7-9af6-dd6b6952b844" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_d38cd730-5b72-4c94-b03a-ed6dfb39f498" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_d38cd730-5b72-4c94-b03a-ed6dfb39f498_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_d38cd730-5b72-4c94-b03a-ed6dfb39f498" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_d38cd730-5b72-4c94-b03a-ed6dfb39f498_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_d71cbf1e-b51c-4b52-ae26-e4b433697f90" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_d38cd730-5b72-4c94-b03a-ed6dfb39f498" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_d71cbf1e-b51c-4b52-ae26-e4b433697f90" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermInvestmentsMember_d13a4105-6181-4ead-8968-23b13a59bb3c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortTermInvestmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_d71cbf1e-b51c-4b52-ae26-e4b433697f90" xlink:to="loc_us-gaap_ShortTermInvestmentsMember_d13a4105-6181-4ead-8968-23b13a59bb3c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_LongtermInvestmentsMember_2cedae67-95e1-4d30-b04a-d5abaf9932ef" xlink:href="vcel-20251231.xsd#vcel_LongtermInvestmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_d71cbf1e-b51c-4b52-ae26-e4b433697f90" xlink:to="loc_vcel_LongtermInvestmentsMember_2cedae67-95e1-4d30-b04a-d5abaf9932ef" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_a9e9aa46-96c1-4211-baa9-ddb348b0c93b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_6ad32856-3184-48b7-a134-51143c0acef5" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_a9e9aa46-96c1-4211-baa9-ddb348b0c93b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_5527c0cd-919f-470a-888f-f5427261e879" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_6ad32856-3184-48b7-a134-51143c0acef5" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_5527c0cd-919f-470a-888f-f5427261e879" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_d5990817-cd6c-452e-a9c2-eb8b25bdcef8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_6ad32856-3184-48b7-a134-51143c0acef5" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_d5990817-cd6c-452e-a9c2-eb8b25bdcef8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLoss_bc1fdc8c-aecd-453d-ba7e-8e1671b93b12" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_6ad32856-3184-48b7-a134-51143c0acef5" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLoss_bc1fdc8c-aecd-453d-ba7e-8e1671b93b12" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_0b1bac4f-1055-41bd-a5a9-937b65d22c94" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_6ad32856-3184-48b7-a134-51143c0acef5" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_0b1bac4f-1055-41bd-a5a9-937b65d22c94" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://vcel.com/role/StockBasedCompensationNarrativeDetails" xlink:type="simple" xlink:href="vcel-20251231.xsd#StockBasedCompensationNarrativeDetails"/>
  <link:definitionLink xlink:role="http://vcel.com/role/StockBasedCompensationNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7c093897-752d-4dc4-bd35-05f5aab11907" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f75d6fe4-cff2-43f4-a471-61d92098df8a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7c093897-752d-4dc4-bd35-05f5aab11907" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f75d6fe4-cff2-43f4-a471-61d92098df8a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_07e6412c-8b14-4a63-aab3-ea64b506aaf0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f75d6fe4-cff2-43f4-a471-61d92098df8a" xlink:to="loc_us-gaap_AwardTypeAxis_07e6412c-8b14-4a63-aab3-ea64b506aaf0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_07e6412c-8b14-4a63-aab3-ea64b506aaf0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_07e6412c-8b14-4a63-aab3-ea64b506aaf0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_07e6412c-8b14-4a63-aab3-ea64b506aaf0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_5cb4fdfc-1526-4a7f-a4f3-e698c189f2ef" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_07e6412c-8b14-4a63-aab3-ea64b506aaf0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_5cb4fdfc-1526-4a7f-a4f3-e698c189f2ef" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_a0e2e6d9-045e-4e8e-ac69-01a87f628db7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_5cb4fdfc-1526-4a7f-a4f3-e698c189f2ef" xlink:to="loc_us-gaap_EmployeeStockOptionMember_a0e2e6d9-045e-4e8e-ac69-01a87f628db7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_7be69f65-305d-45f2-8bed-1042aef19bd4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_5cb4fdfc-1526-4a7f-a4f3-e698c189f2ef" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_7be69f65-305d-45f2-8bed-1042aef19bd4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockMember_2b5ab589-8c56-4bd9-8a19-fe6c7e8bc098" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_5cb4fdfc-1526-4a7f-a4f3-e698c189f2ef" xlink:to="loc_us-gaap_EmployeeStockMember_2b5ab589-8c56-4bd9-8a19-fe6c7e8bc098" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardDateAxis_ee28116e-2a26-48a6-85b1-9de496251a62" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardDateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f75d6fe4-cff2-43f4-a471-61d92098df8a" xlink:to="loc_us-gaap_AwardDateAxis_ee28116e-2a26-48a6-85b1-9de496251a62" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardDateDomain_ee28116e-2a26-48a6-85b1-9de496251a62_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardDateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardDateAxis_ee28116e-2a26-48a6-85b1-9de496251a62" xlink:to="loc_us-gaap_AwardDateDomain_ee28116e-2a26-48a6-85b1-9de496251a62_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardDateDomain_d9a7a880-1e83-45b3-b0ca-da3e0bef10e0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardDateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardDateAxis_ee28116e-2a26-48a6-85b1-9de496251a62" xlink:to="loc_us-gaap_AwardDateDomain_d9a7a880-1e83-45b3-b0ca-da3e0bef10e0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_AwardDatePeriodOneMember_07973ff1-5c10-4e81-a1cd-e8621e7777fe" xlink:href="vcel-20251231.xsd#vcel_AwardDatePeriodOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AwardDateDomain_d9a7a880-1e83-45b3-b0ca-da3e0bef10e0" xlink:to="loc_vcel_AwardDatePeriodOneMember_07973ff1-5c10-4e81-a1cd-e8621e7777fe" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_AwardDatePeriodTwoMember_d708fd33-dcc1-4c8e-b5fc-05df36792f89" xlink:href="vcel-20251231.xsd#vcel_AwardDatePeriodTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AwardDateDomain_d9a7a880-1e83-45b3-b0ca-da3e0bef10e0" xlink:to="loc_vcel_AwardDatePeriodTwoMember_d708fd33-dcc1-4c8e-b5fc-05df36792f89" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GranteeStatusAxis_232fb4d7-e96d-4027-b111-b3e4882f7ede" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GranteeStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f75d6fe4-cff2-43f4-a471-61d92098df8a" xlink:to="loc_us-gaap_GranteeStatusAxis_232fb4d7-e96d-4027-b111-b3e4882f7ede" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GranteeStatusDomain_232fb4d7-e96d-4027-b111-b3e4882f7ede_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GranteeStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_GranteeStatusAxis_232fb4d7-e96d-4027-b111-b3e4882f7ede" xlink:to="loc_us-gaap_GranteeStatusDomain_232fb4d7-e96d-4027-b111-b3e4882f7ede_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GranteeStatusDomain_bb4ce9f3-f49d-4f95-9abd-14a46498d030" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GranteeStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_GranteeStatusAxis_232fb4d7-e96d-4027-b111-b3e4882f7ede" xlink:to="loc_us-gaap_GranteeStatusDomain_bb4ce9f3-f49d-4f95-9abd-14a46498d030" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedPaymentArrangementNonemployeeMember_57ea9120-bf22-427f-bd64-69c87903acf0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedPaymentArrangementNonemployeeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GranteeStatusDomain_bb4ce9f3-f49d-4f95-9abd-14a46498d030" xlink:to="loc_us-gaap_ShareBasedPaymentArrangementNonemployeeMember_57ea9120-bf22-427f-bd64-69c87903acf0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_24055d07-45ba-4d7e-9d91-080bd3f22bd6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7c093897-752d-4dc4-bd35-05f5aab11907" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_24055d07-45ba-4d7e-9d91-080bd3f22bd6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_918ba6ed-3654-455f-a7d5-947d5a6ee27c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7c093897-752d-4dc4-bd35-05f5aab11907" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_918ba6ed-3654-455f-a7d5-947d5a6ee27c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_fdcda3b5-d3a6-4eb2-bcff-8085ba52dec6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7c093897-752d-4dc4-bd35-05f5aab11907" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_fdcda3b5-d3a6-4eb2-bcff-8085ba52dec6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber_fb01a413-5909-4819-956f-78fb925b5036" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7c093897-752d-4dc4-bd35-05f5aab11907" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber_fb01a413-5909-4819-956f-78fb925b5036" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_db5ede0a-98bd-42e9-be9c-874d7f35b40a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7c093897-752d-4dc4-bd35-05f5aab11907" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_db5ede0a-98bd-42e9-be9c-874d7f35b40a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_ec7dd36f-a4c3-429d-93c6-a84d08a6e277" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7c093897-752d-4dc4-bd35-05f5aab11907" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_ec7dd36f-a4c3-429d-93c6-a84d08a6e277" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_ac40c4b6-98cf-4924-99e1-c684466b9f9b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7c093897-752d-4dc4-bd35-05f5aab11907" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_ac40c4b6-98cf-4924-99e1-c684466b9f9b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_c06d06d0-92e2-490f-a089-bb167340e9c3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7c093897-752d-4dc4-bd35-05f5aab11907" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_c06d06d0-92e2-490f-a089-bb167340e9c3" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_3cb44176-4aac-496e-8644-8a44e4aada25" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7c093897-752d-4dc4-bd35-05f5aab11907" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_3cb44176-4aac-496e-8644-8a44e4aada25" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_710a2e74-35ff-456c-8df5-fcac6083888b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7c093897-752d-4dc4-bd35-05f5aab11907" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_710a2e74-35ff-456c-8df5-fcac6083888b" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_35fe4db0-2e14-4540-9a96-256e641a70e1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7c093897-752d-4dc4-bd35-05f5aab11907" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_35fe4db0-2e14-4540-9a96-256e641a70e1" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod_3260b657-e45f-44cc-b763-3395cb14b710" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7c093897-752d-4dc4-bd35-05f5aab11907" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod_3260b657-e45f-44cc-b763-3395cb14b710" xlink:type="arc" order="11"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://vcel.com/role/StockBasedCompensationScheduleofnoncashstockbasedcompensationexpenseDetails" xlink:type="simple" xlink:href="vcel-20251231.xsd#StockBasedCompensationScheduleofnoncashstockbasedcompensationexpenseDetails"/>
  <link:definitionLink xlink:role="http://vcel.com/role/StockBasedCompensationScheduleofnoncashstockbasedcompensationexpenseDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_a563c33f-e808-4a0a-9325-4a7fc5f8189e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_ce7946d4-193c-4c1e-9b12-fe49fc32fb25" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_a563c33f-e808-4a0a-9325-4a7fc5f8189e" xlink:to="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_ce7946d4-193c-4c1e-9b12-fe49fc32fb25" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_a4ebf79d-0e9c-41b6-ace3-595febee7f2b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_ce7946d4-193c-4c1e-9b12-fe49fc32fb25" xlink:to="loc_us-gaap_AwardTypeAxis_a4ebf79d-0e9c-41b6-ace3-595febee7f2b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a4ebf79d-0e9c-41b6-ace3-595febee7f2b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_a4ebf79d-0e9c-41b6-ace3-595febee7f2b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a4ebf79d-0e9c-41b6-ace3-595febee7f2b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_bd44e59e-f568-48f6-9bc3-489ba2987950" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_a4ebf79d-0e9c-41b6-ace3-595febee7f2b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_bd44e59e-f568-48f6-9bc3-489ba2987950" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_EmployeeStockAndEmployeeStockOptionMember_ef2cd877-2f68-4ef5-b64e-ca8c0ea0029a" xlink:href="vcel-20251231.xsd#vcel_EmployeeStockAndEmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_bd44e59e-f568-48f6-9bc3-489ba2987950" xlink:to="loc_vcel_EmployeeStockAndEmployeeStockOptionMember_ef2cd877-2f68-4ef5-b64e-ca8c0ea0029a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_170f3dc4-c7e0-4fda-b64d-5b6912999df9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_ce7946d4-193c-4c1e-9b12-fe49fc32fb25" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_170f3dc4-c7e0-4fda-b64d-5b6912999df9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_170f3dc4-c7e0-4fda-b64d-5b6912999df9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_170f3dc4-c7e0-4fda-b64d-5b6912999df9" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_170f3dc4-c7e0-4fda-b64d-5b6912999df9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_fce1de96-4502-455b-a758-7776415d6c34" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_170f3dc4-c7e0-4fda-b64d-5b6912999df9" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_fce1de96-4502-455b-a758-7776415d6c34" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfSalesMember_3679eeea-8af1-4f93-865c-190f2f58bb83" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostOfSalesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_fce1de96-4502-455b-a758-7776415d6c34" xlink:to="loc_us-gaap_CostOfSalesMember_3679eeea-8af1-4f93-865c-190f2f58bb83" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpenseMember_005a1a78-686c-46c8-b3f9-9a4b65426dcc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ResearchAndDevelopmentExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_fce1de96-4502-455b-a758-7776415d6c34" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpenseMember_005a1a78-686c-46c8-b3f9-9a4b65426dcc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_5003e619-9ee2-4458-9799-435d1a43b92b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SellingGeneralAndAdministrativeExpensesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_fce1de96-4502-455b-a758-7776415d6c34" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_5003e619-9ee2-4458-9799-435d1a43b92b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_5f107a2a-54e0-4726-8d6c-dfb58a9c0f66" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_a563c33f-e808-4a0a-9325-4a7fc5f8189e" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_5f107a2a-54e0-4726-8d6c-dfb58a9c0f66" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://vcel.com/role/StockBasedCompensationScheduleoffairvalueassumptionsDetails" xlink:type="simple" xlink:href="vcel-20251231.xsd#StockBasedCompensationScheduleoffairvalueassumptionsDetails"/>
  <link:definitionLink xlink:role="http://vcel.com/role/StockBasedCompensationScheduleoffairvalueassumptionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_40bc4824-0234-4d8b-9099-40da605efc41" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_6313ee09-38cb-41e2-ab59-53ba1c7541a5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_40bc4824-0234-4d8b-9099-40da605efc41" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_6313ee09-38cb-41e2-ab59-53ba1c7541a5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_6e86bda9-99dd-4cff-9ed6-7ee929680136" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_6313ee09-38cb-41e2-ab59-53ba1c7541a5" xlink:to="loc_us-gaap_AwardTypeAxis_6e86bda9-99dd-4cff-9ed6-7ee929680136" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6e86bda9-99dd-4cff-9ed6-7ee929680136_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_6e86bda9-99dd-4cff-9ed6-7ee929680136" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6e86bda9-99dd-4cff-9ed6-7ee929680136_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_7e8f7dc2-83d7-4c18-ae84-02dd8c37c8a7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_6e86bda9-99dd-4cff-9ed6-7ee929680136" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_7e8f7dc2-83d7-4c18-ae84-02dd8c37c8a7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_0521000d-76d1-4237-8045-c2c4b59ecb99" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_7e8f7dc2-83d7-4c18-ae84-02dd8c37c8a7" xlink:to="loc_us-gaap_EmployeeStockOptionMember_0521000d-76d1-4237-8045-c2c4b59ecb99" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_957a675b-2f78-48e4-ad32-453157cda034" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_40bc4824-0234-4d8b-9099-40da605efc41" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_957a675b-2f78-48e4-ad32-453157cda034" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum_4d680f8e-67df-45d5-8b0f-def62dc8a2b4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_40bc4824-0234-4d8b-9099-40da605efc41" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum_4d680f8e-67df-45d5-8b0f-def62dc8a2b4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum_0bf18f62-d5f5-4791-9081-53da3d8bebec" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_40bc4824-0234-4d8b-9099-40da605efc41" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum_0bf18f62-d5f5-4791-9081-53da3d8bebec" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum_2b2736cb-65bf-4478-ba29-1c8325e17a19" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_40bc4824-0234-4d8b-9099-40da605efc41" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum_2b2736cb-65bf-4478-ba29-1c8325e17a19" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum_b32a8856-3275-4a5c-b17b-bab5be67f66d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_40bc4824-0234-4d8b-9099-40da605efc41" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum_b32a8856-3275-4a5c-b17b-bab5be67f66d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_72e5492e-7c60-4a4d-9bbf-f424b72ab984" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_40bc4824-0234-4d8b-9099-40da605efc41" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_72e5492e-7c60-4a4d-9bbf-f424b72ab984" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_b294c3a2-8527-4aea-8b94-8114453e6fb8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_40bc4824-0234-4d8b-9099-40da605efc41" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_b294c3a2-8527-4aea-8b94-8114453e6fb8" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://vcel.com/role/StockBasedCompensationScheduleofrestrictedstockawardsactivityDetails" xlink:type="simple" xlink:href="vcel-20251231.xsd#StockBasedCompensationScheduleofrestrictedstockawardsactivityDetails"/>
  <link:definitionLink xlink:role="http://vcel.com/role/StockBasedCompensationScheduleofrestrictedstockawardsactivityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c4de21fd-bb33-47e6-b218-2603dbf60487" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_6bed0007-0c48-4d4c-9cb0-4d5bb0995149" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c4de21fd-bb33-47e6-b218-2603dbf60487" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_6bed0007-0c48-4d4c-9cb0-4d5bb0995149" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_fd855aa5-a12e-48bd-b214-436da5565aa7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_6bed0007-0c48-4d4c-9cb0-4d5bb0995149" xlink:to="loc_us-gaap_AwardTypeAxis_fd855aa5-a12e-48bd-b214-436da5565aa7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_fd855aa5-a12e-48bd-b214-436da5565aa7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_fd855aa5-a12e-48bd-b214-436da5565aa7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_fd855aa5-a12e-48bd-b214-436da5565aa7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_d667cb71-8f6a-4bf8-9e8b-761af8f95bfd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_fd855aa5-a12e-48bd-b214-436da5565aa7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_d667cb71-8f6a-4bf8-9e8b-761af8f95bfd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_8715b2c6-9c34-41e6-8421-bee187c2bb7e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_d667cb71-8f6a-4bf8-9e8b-761af8f95bfd" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_8715b2c6-9c34-41e6-8421-bee187c2bb7e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_1ceb85a2-3080-4c98-b485-73c3caf43f6c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c4de21fd-bb33-47e6-b218-2603dbf60487" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_1ceb85a2-3080-4c98-b485-73c3caf43f6c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_c4e00d4b-0eeb-4b76-be3a-cc91d67f7f82" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_1ceb85a2-3080-4c98-b485-73c3caf43f6c" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_c4e00d4b-0eeb-4b76-be3a-cc91d67f7f82" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_f991afa0-3d9e-4cb5-b5b4-12e66041a9af" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_1ceb85a2-3080-4c98-b485-73c3caf43f6c" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_f991afa0-3d9e-4cb5-b5b4-12e66041a9af" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_8765ac39-a635-45c7-969b-27761b9f30e8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_1ceb85a2-3080-4c98-b485-73c3caf43f6c" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_8765ac39-a635-45c7-969b-27761b9f30e8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_dcc17265-a0fe-4f15-93ee-15b90e6576b6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_1ceb85a2-3080-4c98-b485-73c3caf43f6c" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_dcc17265-a0fe-4f15-93ee-15b90e6576b6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_c695af4d-7e25-480f-b589-0e1aab5babe5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_9f4ba9c4-57aa-41f1-882f-e15a3b177742" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c4de21fd-bb33-47e6-b218-2603dbf60487" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_9f4ba9c4-57aa-41f1-882f-e15a3b177742" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_b8932a59-7a4f-4541-8fc2-b9ac4219ae42" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_9f4ba9c4-57aa-41f1-882f-e15a3b177742" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_b8932a59-7a4f-4541-8fc2-b9ac4219ae42" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_789ea42b-f5fb-445a-a56d-fe75b894f0a2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_9f4ba9c4-57aa-41f1-882f-e15a3b177742" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_789ea42b-f5fb-445a-a56d-fe75b894f0a2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_7b033aca-1717-4e1f-80bb-894c8a8acc61" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_9f4ba9c4-57aa-41f1-882f-e15a3b177742" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_7b033aca-1717-4e1f-80bb-894c8a8acc61" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_66fa86a4-d128-4a28-95a4-86fbb8902dbe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_9f4ba9c4-57aa-41f1-882f-e15a3b177742" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_66fa86a4-d128-4a28-95a4-86fbb8902dbe" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_0e9f697a-75cd-4082-872e-806856d20916" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://vcel.com/role/RevolvingCreditAgreementDetails" xlink:type="simple" xlink:href="vcel-20251231.xsd#RevolvingCreditAgreementDetails"/>
  <link:definitionLink xlink:role="http://vcel.com/role/RevolvingCreditAgreementDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_73ac4d83-581d-46ce-9fbd-4e357bdb1616" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_f25f6e14-6350-41c2-8add-8b0b199165ec" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_73ac4d83-581d-46ce-9fbd-4e357bdb1616" xlink:to="loc_us-gaap_DebtInstrumentTable_f25f6e14-6350-41c2-8add-8b0b199165ec" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_1c201312-7ad6-47bb-8ff5-6ac910ff5805" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_f25f6e14-6350-41c2-8add-8b0b199165ec" xlink:to="loc_us-gaap_CreditFacilityAxis_1c201312-7ad6-47bb-8ff5-6ac910ff5805" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_1c201312-7ad6-47bb-8ff5-6ac910ff5805_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_1c201312-7ad6-47bb-8ff5-6ac910ff5805" xlink:to="loc_us-gaap_CreditFacilityDomain_1c201312-7ad6-47bb-8ff5-6ac910ff5805_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_99e9aa3a-dba1-46c6-8949-413a8b611e7b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_1c201312-7ad6-47bb-8ff5-6ac910ff5805" xlink:to="loc_us-gaap_CreditFacilityDomain_99e9aa3a-dba1-46c6-8949-413a8b611e7b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_2abae3d2-0b37-46ee-b4e4-a485e9535300" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_99e9aa3a-dba1-46c6-8949-413a8b611e7b" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_2abae3d2-0b37-46ee-b4e4-a485e9535300" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LetterOfCreditMember_49e168dd-660e-4807-ac39-25951b828b78" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LetterOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_99e9aa3a-dba1-46c6-8949-413a8b611e7b" xlink:to="loc_us-gaap_LetterOfCreditMember_49e168dd-660e-4807-ac39-25951b828b78" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_15e544c1-2c10-44c4-83cb-69ab0b1745b8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_f25f6e14-6350-41c2-8add-8b0b199165ec" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_15e544c1-2c10-44c4-83cb-69ab0b1745b8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_15e544c1-2c10-44c4-83cb-69ab0b1745b8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_15e544c1-2c10-44c4-83cb-69ab0b1745b8" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_15e544c1-2c10-44c4-83cb-69ab0b1745b8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_7686a352-9cf1-4a49-afd4-9a630dfc5333" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_15e544c1-2c10-44c4-83cb-69ab0b1745b8" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_7686a352-9cf1-4a49-afd4-9a630dfc5333" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_7f04bd6b-e946-401c-84f0-d78f2ed7803f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_7686a352-9cf1-4a49-afd4-9a630dfc5333" xlink:to="loc_us-gaap_LineOfCreditMember_7f04bd6b-e946-401c-84f0-d78f2ed7803f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_42ba17b9-5635-48cd-80f2-1b4026603b81" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VariableRateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_f25f6e14-6350-41c2-8add-8b0b199165ec" xlink:to="loc_us-gaap_VariableRateAxis_42ba17b9-5635-48cd-80f2-1b4026603b81" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_42ba17b9-5635-48cd-80f2-1b4026603b81_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_42ba17b9-5635-48cd-80f2-1b4026603b81" xlink:to="loc_us-gaap_VariableRateDomain_42ba17b9-5635-48cd-80f2-1b4026603b81_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_5774be36-bb52-4791-84ba-1a74f39a8f3c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_42ba17b9-5635-48cd-80f2-1b4026603b81" xlink:to="loc_us-gaap_VariableRateDomain_5774be36-bb52-4791-84ba-1a74f39a8f3c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredOvernightFinancingRateSofrMember_3ee07414-4cf4-42b1-840a-afffb70493db" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SecuredOvernightFinancingRateSofrMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_5774be36-bb52-4791-84ba-1a74f39a8f3c" xlink:to="loc_us-gaap_SecuredOvernightFinancingRateSofrMember_3ee07414-4cf4-42b1-840a-afffb70493db" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BaseRateMember_84fc3f76-6ab0-473d-99de-3031f0bd84e3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BaseRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_5774be36-bb52-4791-84ba-1a74f39a8f3c" xlink:to="loc_us-gaap_BaseRateMember_84fc3f76-6ab0-473d-99de-3031f0bd84e3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_8da3b20c-7870-44f3-af97-2d3767e46e27" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_f25f6e14-6350-41c2-8add-8b0b199165ec" xlink:to="loc_srt_RangeAxis_8da3b20c-7870-44f3-af97-2d3767e46e27" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_8da3b20c-7870-44f3-af97-2d3767e46e27_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_8da3b20c-7870-44f3-af97-2d3767e46e27" xlink:to="loc_srt_RangeMember_8da3b20c-7870-44f3-af97-2d3767e46e27_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_6f8442cc-8a2b-44e8-8ffe-d3cdf56ce8b7" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_8da3b20c-7870-44f3-af97-2d3767e46e27" xlink:to="loc_srt_RangeMember_6f8442cc-8a2b-44e8-8ffe-d3cdf56ce8b7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_6da5ebad-ceb6-4f19-8720-9821c1dfcaab" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_6f8442cc-8a2b-44e8-8ffe-d3cdf56ce8b7" xlink:to="loc_srt_MinimumMember_6da5ebad-ceb6-4f19-8720-9821c1dfcaab" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_b158965c-9831-4225-bf07-ff0adb37cd6f" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_6f8442cc-8a2b-44e8-8ffe-d3cdf56ce8b7" xlink:to="loc_srt_MaximumMember_b158965c-9831-4225-bf07-ff0adb37cd6f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_5c98b02a-8f0b-4ac7-a4e4-d5a343534260" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_73ac4d83-581d-46ce-9fbd-4e357bdb1616" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_5c98b02a-8f0b-4ac7-a4e4-d5a343534260" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTerm_b930df77-438e-4cc5-938a-385212fa82fa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_73ac4d83-581d-46ce-9fbd-4e357bdb1616" xlink:to="loc_us-gaap_DebtInstrumentTerm_b930df77-438e-4cc5-938a-385212fa82fa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount_aebac39c-53fc-4bd2-a84c-c5ad7c9f5226" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LettersOfCreditOutstandingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_73ac4d83-581d-46ce-9fbd-4e357bdb1616" xlink:to="loc_us-gaap_LettersOfCreditOutstandingAmount_aebac39c-53fc-4bd2-a84c-c5ad7c9f5226" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsNet_823a6a3b-66e3-4fd0-9414-e1f14ac0ec0b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredFinanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_73ac4d83-581d-46ce-9fbd-4e357bdb1616" xlink:to="loc_us-gaap_DeferredFinanceCostsNet_823a6a3b-66e3-4fd0-9414-e1f14ac0ec0b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_705969be-fd44-41f8-b39c-3b1f86c0bb94" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_73ac4d83-581d-46ce-9fbd-4e357bdb1616" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_705969be-fd44-41f8-b39c-3b1f86c0bb94" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_cf3cf0b5-8c6e-47bf-8278-a60547ae4322" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditFacilityCommitmentFeePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_73ac4d83-581d-46ce-9fbd-4e357bdb1616" xlink:to="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_cf3cf0b5-8c6e-47bf-8278-a60547ae4322" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCredit_7c9b8b87-c10e-4d6d-9ed2-82f6cc925d0e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_73ac4d83-581d-46ce-9fbd-4e357bdb1616" xlink:to="loc_us-gaap_LineOfCredit_7c9b8b87-c10e-4d6d-9ed2-82f6cc925d0e" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_DebtInstrumentCovenantLeverageRatioMaximum_aa32cc9d-8ebb-4a45-94b9-445dfdb1ba22" xlink:href="vcel-20251231.xsd#vcel_DebtInstrumentCovenantLeverageRatioMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_73ac4d83-581d-46ce-9fbd-4e357bdb1616" xlink:to="loc_vcel_DebtInstrumentCovenantLeverageRatioMaximum_aa32cc9d-8ebb-4a45-94b9-445dfdb1ba22" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_DebtInstrumentCovenantIncreaseOptionLeverageRatioMaximum_add7507b-6a9c-4f76-a29a-0df3ae77ecbc" xlink:href="vcel-20251231.xsd#vcel_DebtInstrumentCovenantIncreaseOptionLeverageRatioMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_73ac4d83-581d-46ce-9fbd-4e357bdb1616" xlink:to="loc_vcel_DebtInstrumentCovenantIncreaseOptionLeverageRatioMaximum_add7507b-6a9c-4f76-a29a-0df3ae77ecbc" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://vcel.com/role/NetIncomeLossPerCommonShareDetails" xlink:type="simple" xlink:href="vcel-20251231.xsd#NetIncomeLossPerCommonShareDetails"/>
  <link:definitionLink xlink:role="http://vcel.com/role/NetIncomeLossPerCommonShareDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_e7162ebc-5a33-49aa-a7aa-ecedcc67bd68" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_a77619fb-6ee2-43c0-99cb-d59497582101" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_e7162ebc-5a33-49aa-a7aa-ecedcc67bd68" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_a77619fb-6ee2-43c0-99cb-d59497582101" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_4f6cceb6-20be-4120-98cd-37c1ea7aec04" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_a77619fb-6ee2-43c0-99cb-d59497582101" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_4f6cceb6-20be-4120-98cd-37c1ea7aec04" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_4f6cceb6-20be-4120-98cd-37c1ea7aec04_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_4f6cceb6-20be-4120-98cd-37c1ea7aec04" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_4f6cceb6-20be-4120-98cd-37c1ea7aec04_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_ea9d9cf9-b114-4137-b1d6-05140d76090e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_4f6cceb6-20be-4120-98cd-37c1ea7aec04" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_ea9d9cf9-b114-4137-b1d6-05140d76090e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_c9cc9316-bf52-4800-80ce-3806b16dca63" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_ea9d9cf9-b114-4137-b1d6-05140d76090e" xlink:to="loc_us-gaap_EmployeeStockOptionMember_c9cc9316-bf52-4800-80ce-3806b16dca63" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_91b58ef2-7104-4e53-bf5a-6bf9bf9fdbd3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_ea9d9cf9-b114-4137-b1d6-05140d76090e" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_91b58ef2-7104-4e53-bf5a-6bf9bf9fdbd3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAbstract_1d8c6307-b39b-45c9-9cc2-f5fcfb94736a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLossAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_e7162ebc-5a33-49aa-a7aa-ecedcc67bd68" xlink:to="loc_us-gaap_NetIncomeLossAbstract_1d8c6307-b39b-45c9-9cc2-f5fcfb94736a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_141be736-ba2e-4a34-a1da-0a62b7533c21" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetIncomeLossAbstract_1d8c6307-b39b-45c9-9cc2-f5fcfb94736a" xlink:to="loc_us-gaap_NetIncomeLoss_141be736-ba2e-4a34-a1da-0a62b7533c21" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_6f3b4f1a-2e05-41b5-9020-8618c099dd37" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetIncomeLossAbstract_1d8c6307-b39b-45c9-9cc2-f5fcfb94736a" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_6f3b4f1a-2e05-41b5-9020-8618c099dd37" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_f99e246e-a9db-4713-80e2-5c5ac3b4a4bf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetIncomeLossAbstract_1d8c6307-b39b-45c9-9cc2-f5fcfb94736a" xlink:to="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_f99e246e-a9db-4713-80e2-5c5ac3b4a4bf" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_32db170d-00b2-4c45-922d-c3b2f54873e4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetIncomeLossAbstract_1d8c6307-b39b-45c9-9cc2-f5fcfb94736a" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_32db170d-00b2-4c45-922d-c3b2f54873e4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_227b295b-e0d4-4a77-851f-3b2fa911f5bd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetIncomeLossAbstract_1d8c6307-b39b-45c9-9cc2-f5fcfb94736a" xlink:to="loc_us-gaap_EarningsPerShareBasic_227b295b-e0d4-4a77-851f-3b2fa911f5bd" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_cd18d90c-4395-46bc-bac9-8c52282c3561" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetIncomeLossAbstract_1d8c6307-b39b-45c9-9cc2-f5fcfb94736a" xlink:to="loc_us-gaap_EarningsPerShareDiluted_cd18d90c-4395-46bc-bac9-8c52282c3561" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_e1f5e127-ccfa-4e40-bb80-56fdc7d474df" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_e7162ebc-5a33-49aa-a7aa-ecedcc67bd68" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_e1f5e127-ccfa-4e40-bb80-56fdc7d474df" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_a86de2eb-09c2-4232-9b1a-72501bdfb764" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_e1f5e127-ccfa-4e40-bb80-56fdc7d474df" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_a86de2eb-09c2-4232-9b1a-72501bdfb764" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://vcel.com/role/FairValueMeasurementsDetails" xlink:type="simple" xlink:href="vcel-20251231.xsd#FairValueMeasurementsDetails"/>
  <link:definitionLink xlink:role="http://vcel.com/role/FairValueMeasurementsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_5a4091f6-5e71-4b02-800d-017a2ef10301" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_74f2862d-964c-408f-a389-74b5dc1eaf54" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_5a4091f6-5e71-4b02-800d-017a2ef10301" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_74f2862d-964c-408f-a389-74b5dc1eaf54" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAxis_f90184d8-9445-4c29-88e3-38b9c56b94d0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_74f2862d-964c-408f-a389-74b5dc1eaf54" xlink:to="loc_us-gaap_CashAndCashEquivalentsAxis_f90184d8-9445-4c29-88e3-38b9c56b94d0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_f90184d8-9445-4c29-88e3-38b9c56b94d0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CashAndCashEquivalentsAxis_f90184d8-9445-4c29-88e3-38b9c56b94d0" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_f90184d8-9445-4c29-88e3-38b9c56b94d0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_ed4d9c9c-815b-454d-a9bf-92d7c70d5c94" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CashAndCashEquivalentsAxis_f90184d8-9445-4c29-88e3-38b9c56b94d0" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_ed4d9c9c-815b-454d-a9bf-92d7c70d5c94" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MoneyMarketFundsMember_6f19cfaf-9bea-41cb-a095-7810708e2635" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MoneyMarketFundsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_ed4d9c9c-815b-454d-a9bf-92d7c70d5c94" xlink:to="loc_us-gaap_MoneyMarketFundsMember_6f19cfaf-9bea-41cb-a095-7810708e2635" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_9057af3b-7acc-48bb-bbf4-92a9b9f29bd9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_74f2862d-964c-408f-a389-74b5dc1eaf54" xlink:to="loc_us-gaap_FinancialInstrumentAxis_9057af3b-7acc-48bb-bbf4-92a9b9f29bd9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_9057af3b-7acc-48bb-bbf4-92a9b9f29bd9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_9057af3b-7acc-48bb-bbf4-92a9b9f29bd9" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_9057af3b-7acc-48bb-bbf4-92a9b9f29bd9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_dd0638ec-1f97-469c-ab83-26369a14fcf8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_9057af3b-7acc-48bb-bbf4-92a9b9f29bd9" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_dd0638ec-1f97-469c-ab83-26369a14fcf8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPaperMember_019b2333-ae50-7a60-b3ee-6bdc63ba4509" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommercialPaperMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_dd0638ec-1f97-469c-ab83-26369a14fcf8" xlink:to="loc_us-gaap_CommercialPaperMember_019b2333-ae50-7a60-b3ee-6bdc63ba4509" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNoteSecuritiesMember_da792047-a026-4385-9589-731cb383eff3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CorporateNoteSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_dd0638ec-1f97-469c-ab83-26369a14fcf8" xlink:to="loc_us-gaap_CorporateNoteSecuritiesMember_da792047-a026-4385-9589-731cb383eff3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_6c874343-739b-4e22-9315-23c03bad6288" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USGovernmentAgenciesDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_dd0638ec-1f97-469c-ab83-26369a14fcf8" xlink:to="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_6c874343-739b-4e22-9315-23c03bad6288" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentDebtSecuritiesMember_c63ebd94-d368-494b-84fd-716794d6ebc8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USGovernmentDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_dd0638ec-1f97-469c-ab83-26369a14fcf8" xlink:to="loc_us-gaap_USGovernmentDebtSecuritiesMember_c63ebd94-d368-494b-84fd-716794d6ebc8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_dc69eea3-9f62-460d-958e-8a407718b846" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_74f2862d-964c-408f-a389-74b5dc1eaf54" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_dc69eea3-9f62-460d-958e-8a407718b846" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_dc69eea3-9f62-460d-958e-8a407718b846_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_dc69eea3-9f62-460d-958e-8a407718b846" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_dc69eea3-9f62-460d-958e-8a407718b846_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_b4718feb-6089-4434-9c87-faa9992617f4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_dc69eea3-9f62-460d-958e-8a407718b846" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_b4718feb-6089-4434-9c87-faa9992617f4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_c91914fb-8dd2-4414-9d7e-881ef6322189" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_b4718feb-6089-4434-9c87-faa9992617f4" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_c91914fb-8dd2-4414-9d7e-881ef6322189" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_35392664-6364-4f28-8bb0-5db9e06acefe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_b4718feb-6089-4434-9c87-faa9992617f4" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_35392664-6364-4f28-8bb0-5db9e06acefe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_bd160862-3be8-44d1-a1d3-eaaa8e88faa4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_b4718feb-6089-4434-9c87-faa9992617f4" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_bd160862-3be8-44d1-a1d3-eaaa8e88faa4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_c2435d33-adb4-41d5-9dbb-0eea20b47ed9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_74f2862d-964c-408f-a389-74b5dc1eaf54" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_c2435d33-adb4-41d5-9dbb-0eea20b47ed9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_c2435d33-adb4-41d5-9dbb-0eea20b47ed9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_c2435d33-adb4-41d5-9dbb-0eea20b47ed9" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_c2435d33-adb4-41d5-9dbb-0eea20b47ed9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_4de0ecd0-4f0c-4922-9bea-d64516449596" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_c2435d33-adb4-41d5-9dbb-0eea20b47ed9" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_4de0ecd0-4f0c-4922-9bea-d64516449596" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsMember_b8b82ab1-55cc-4bde-875f-17a4985fed96" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_4de0ecd0-4f0c-4922-9bea-d64516449596" xlink:to="loc_us-gaap_CashAndCashEquivalentsMember_b8b82ab1-55cc-4bde-875f-17a4985fed96" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_ce4c4fca-646e-4eaa-babc-cc673b27804f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_5a4091f6-5e71-4b02-800d-017a2ef10301" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_ce4c4fca-646e-4eaa-babc-cc673b27804f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_2c23f450-0458-4041-be15-71d0c95b0da4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_5a4091f6-5e71-4b02-800d-017a2ef10301" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_2c23f450-0458-4041-be15-71d0c95b0da4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_d96c20e8-0e18-4d50-a013-1001eb90d6ba" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_5a4091f6-5e71-4b02-800d-017a2ef10301" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_d96c20e8-0e18-4d50-a013-1001eb90d6ba" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCompensationLiabilityCurrentAndNoncurrent_f3bbe79c-aeee-4e96-bc2a-7ded54e54a5a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredCompensationLiabilityCurrentAndNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_5a4091f6-5e71-4b02-800d-017a2ef10301" xlink:to="loc_us-gaap_DeferredCompensationLiabilityCurrentAndNoncurrent_f3bbe79c-aeee-4e96-bc2a-7ded54e54a5a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosure_787018b5-5eb6-4e6b-9531-ab6272119f04" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_5a4091f6-5e71-4b02-800d-017a2ef10301" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosure_787018b5-5eb6-4e6b-9531-ab6272119f04" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://vcel.com/role/IncomeTaxesScheduleofIncomeTaxesPaidNetofRefundsDetails" xlink:type="simple" xlink:href="vcel-20251231.xsd#IncomeTaxesScheduleofIncomeTaxesPaidNetofRefundsDetails"/>
  <link:definitionLink xlink:role="http://vcel.com/role/IncomeTaxesScheduleofIncomeTaxesPaidNetofRefundsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxContingencyLineItems_019c32e9-5a30-7a42-8e80-b52dcde8f53f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxContingencyLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxContingencyTable_019c32e9-5a30-70c6-8cc1-fe3854a4b294" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxContingencyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_019c32e9-5a30-7a42-8e80-b52dcde8f53f" xlink:to="loc_us-gaap_IncomeTaxContingencyTable_019c32e9-5a30-70c6-8cc1-fe3854a4b294" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_019c32e9-9ba5-70d6-9120-e7e20c08f1a1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeTaxContingencyTable_019c32e9-5a30-70c6-8cc1-fe3854a4b294" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_019c32e9-9ba5-70d6-9120-e7e20c08f1a1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_019c32e9-9ba5-70d6-9120-e7e20c08f1a1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_019c32e9-9ba5-70d6-9120-e7e20c08f1a1" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_019c32e9-9ba5-70d6-9120-e7e20c08f1a1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_019c32e9-9ba5-7f5e-932a-6c68b8b28a1e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_019c32e9-9ba5-70d6-9120-e7e20c08f1a1" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_019c32e9-9ba5-7f5e-932a-6c68b8b28a1e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StateAndLocalJurisdictionMember_019c32e9-faf3-7837-8dc8-17101c1d68fd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StateAndLocalJurisdictionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_019c32e9-9ba5-7f5e-932a-6c68b8b28a1e" xlink:to="loc_us-gaap_StateAndLocalJurisdictionMember_019c32e9-faf3-7837-8dc8-17101c1d68fd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_stpr_CA_019c32e9-9ba5-7c85-b1cf-a4e2a14bc5ab" xlink:href="https://xbrl.sec.gov/stpr/2025/stpr-2025.xsd#stpr_CA"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StateAndLocalJurisdictionMember_019c32e9-faf3-7837-8dc8-17101c1d68fd" xlink:to="loc_stpr_CA_019c32e9-9ba5-7c85-b1cf-a4e2a14bc5ab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stpr_NY_019c32e9-9ba6-7231-aec6-be41e342ebc6" xlink:href="https://xbrl.sec.gov/stpr/2025/stpr-2025.xsd#stpr_NY"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StateAndLocalJurisdictionMember_019c32e9-faf3-7837-8dc8-17101c1d68fd" xlink:to="loc_stpr_NY_019c32e9-9ba6-7231-aec6-be41e342ebc6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_stpr_MA_019c32e9-9ba6-7a42-8ec1-953439006260" xlink:href="https://xbrl.sec.gov/stpr/2025/stpr-2025.xsd#stpr_MA"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StateAndLocalJurisdictionMember_019c32e9-faf3-7837-8dc8-17101c1d68fd" xlink:to="loc_stpr_MA_019c32e9-9ba6-7a42-8ec1-953439006260" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_stpr_TN_019c32e9-9ba6-7fe1-84d6-e85e505def67" xlink:href="https://xbrl.sec.gov/stpr/2025/stpr-2025.xsd#stpr_TN"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StateAndLocalJurisdictionMember_019c32e9-faf3-7837-8dc8-17101c1d68fd" xlink:to="loc_stpr_TN_019c32e9-9ba6-7fe1-84d6-e85e505def67" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_stpr_LA_019c5a1e-b38b-74bf-b14e-f3b10fb42983" xlink:href="https://xbrl.sec.gov/stpr/2025/stpr-2025.xsd#stpr_LA"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StateAndLocalJurisdictionMember_019c32e9-faf3-7837-8dc8-17101c1d68fd" xlink:to="loc_stpr_LA_019c5a1e-b38b-74bf-b14e-f3b10fb42983" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_stpr_GA_019c32e9-9ba6-7f89-b4ee-06a2c6ef5a4f" xlink:href="https://xbrl.sec.gov/stpr/2025/stpr-2025.xsd#stpr_GA"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StateAndLocalJurisdictionMember_019c32e9-faf3-7837-8dc8-17101c1d68fd" xlink:to="loc_stpr_GA_019c32e9-9ba6-7f89-b4ee-06a2c6ef5a4f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StateAndLocalTaxJurisdictionOtherMember_019c32e9-9ba6-7ed6-ac53-736dd799b3a2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StateAndLocalTaxJurisdictionOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StateAndLocalJurisdictionMember_019c32e9-faf3-7837-8dc8-17101c1d68fd" xlink:to="loc_us-gaap_StateAndLocalTaxJurisdictionOtherMember_019c32e9-9ba6-7ed6-ac53-736dd799b3a2" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxPaidFederalAfterRefundReceived_019c32e9-5a30-72d6-a00b-57adffcb0985" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxPaidFederalAfterRefundReceived"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_019c32e9-5a30-7a42-8e80-b52dcde8f53f" xlink:to="loc_us-gaap_IncomeTaxPaidFederalAfterRefundReceived_019c32e9-5a30-72d6-a00b-57adffcb0985" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxPaidStateAndLocalAfterRefundReceived_019c32e9-5a30-7f64-9bbe-64e355bbc9fb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxPaidStateAndLocalAfterRefundReceived"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_019c32e9-5a30-7a42-8e80-b52dcde8f53f" xlink:to="loc_us-gaap_IncomeTaxPaidStateAndLocalAfterRefundReceived_019c32e9-5a30-7f64-9bbe-64e355bbc9fb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxPaidForeignAfterRefundReceived_019c32e9-5a30-7832-970c-4aaa49c70d0a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxPaidForeignAfterRefundReceived"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_019c32e9-5a30-7a42-8e80-b52dcde8f53f" xlink:to="loc_us-gaap_IncomeTaxPaidForeignAfterRefundReceived_019c32e9-5a30-7832-970c-4aaa49c70d0a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxesPaidNet_019c32e9-5a30-75db-a1b7-36bbd8bdfb80" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxesPaidNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_019c32e9-5a30-7a42-8e80-b52dcde8f53f" xlink:to="loc_us-gaap_IncomeTaxesPaidNet_019c32e9-5a30-75db-a1b7-36bbd8bdfb80" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://vcel.com/role/IncomeTaxesNarrativeDetails" xlink:type="simple" xlink:href="vcel-20251231.xsd#IncomeTaxesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://vcel.com/role/IncomeTaxesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwardsLineItems_83bde045-35b5-4d0f-98cc-f8369a0568bf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLossCarryforwardsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwardsTable_37667036-3030-4e11-91d1-0d0d36de5acc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLossCarryforwardsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_83bde045-35b5-4d0f-98cc-f8369a0568bf" xlink:to="loc_us-gaap_OperatingLossCarryforwardsTable_37667036-3030-4e11-91d1-0d0d36de5acc" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_e1453f6d-da64-4383-87b6-76e4f643222e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OperatingLossCarryforwardsTable_37667036-3030-4e11-91d1-0d0d36de5acc" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_e1453f6d-da64-4383-87b6-76e4f643222e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_e1453f6d-da64-4383-87b6-76e4f643222e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_e1453f6d-da64-4383-87b6-76e4f643222e" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_e1453f6d-da64-4383-87b6-76e4f643222e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_013cac65-c3f0-4442-887a-5002086b4ca3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_e1453f6d-da64-4383-87b6-76e4f643222e" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_013cac65-c3f0-4442-887a-5002086b4ca3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DomesticCountryMember_ec7c3d91-95a5-4b54-a8c2-1458a0126fcc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DomesticCountryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_013cac65-c3f0-4442-887a-5002086b4ca3" xlink:to="loc_us-gaap_DomesticCountryMember_ec7c3d91-95a5-4b54-a8c2-1458a0126fcc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StateAndLocalJurisdictionMember_d3fb9d2f-7c74-4666-8c28-663d7eb501bd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StateAndLocalJurisdictionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_013cac65-c3f0-4442-887a-5002086b4ca3" xlink:to="loc_us-gaap_StateAndLocalJurisdictionMember_d3fb9d2f-7c74-4666-8c28-663d7eb501bd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityNameAxis_94bdcd62-6c24-4bdb-822e-f7928a472bfb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OperatingLossCarryforwardsTable_37667036-3030-4e11-91d1-0d0d36de5acc" xlink:to="loc_us-gaap_IncomeTaxAuthorityNameAxis_94bdcd62-6c24-4bdb-822e-f7928a472bfb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityNameDomain_94bdcd62-6c24-4bdb-822e-f7928a472bfb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityNameAxis_94bdcd62-6c24-4bdb-822e-f7928a472bfb" xlink:to="loc_us-gaap_IncomeTaxAuthorityNameDomain_94bdcd62-6c24-4bdb-822e-f7928a472bfb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityNameDomain_16717ed5-7b20-497c-a0b6-c6a190a7ae3b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityNameAxis_94bdcd62-6c24-4bdb-822e-f7928a472bfb" xlink:to="loc_us-gaap_IncomeTaxAuthorityNameDomain_16717ed5-7b20-497c-a0b6-c6a190a7ae3b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InternalRevenueServiceIRSMember_57852123-9653-4e06-a0f3-f4d1192feba6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InternalRevenueServiceIRSMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityNameDomain_16717ed5-7b20-497c-a0b6-c6a190a7ae3b" xlink:to="loc_us-gaap_InternalRevenueServiceIRSMember_57852123-9653-4e06-a0f3-f4d1192feba6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwards_a9bec0ea-3701-45ec-97a1-1678a5b1281a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLossCarryforwards"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_83bde045-35b5-4d0f-98cc-f8369a0568bf" xlink:to="loc_us-gaap_OperatingLossCarryforwards_a9bec0ea-3701-45ec-97a1-1678a5b1281a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_OperatingLossCarryforwardsWithExpiration_d2f245ba-b715-4ff1-9f20-8e424603e0c5" xlink:href="vcel-20251231.xsd#vcel_OperatingLossCarryforwardsWithExpiration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_83bde045-35b5-4d0f-98cc-f8369a0568bf" xlink:to="loc_vcel_OperatingLossCarryforwardsWithExpiration_d2f245ba-b715-4ff1-9f20-8e424603e0c5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_OperatingLossCarryforwardsLimitationsOnUseProjectedAnnualLimitationOnUseOfNetOperatingLosses_f25b8d18-180a-42ee-9ba7-79196a255a54" xlink:href="vcel-20251231.xsd#vcel_OperatingLossCarryforwardsLimitationsOnUseProjectedAnnualLimitationOnUseOfNetOperatingLosses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_83bde045-35b5-4d0f-98cc-f8369a0568bf" xlink:to="loc_vcel_OperatingLossCarryforwardsLimitationsOnUseProjectedAnnualLimitationOnUseOfNetOperatingLosses_f25b8d18-180a-42ee-9ba7-79196a255a54" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsGeneralBusiness_519b7f72-a077-4664-a166-893213a23c70" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsGeneralBusiness"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_83bde045-35b5-4d0f-98cc-f8369a0568bf" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsGeneralBusiness_519b7f72-a077-4664-a166-893213a23c70" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount_a7900cd0-03dd-4180-94b7-46fcee7abbcb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_83bde045-35b5-4d0f-98cc-f8369a0568bf" xlink:to="loc_us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount_a7900cd0-03dd-4180-94b7-46fcee7abbcb" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://vcel.com/role/NexoBridLicenseandSupplyAgreementsDetails" xlink:type="simple" xlink:href="vcel-20251231.xsd#NexoBridLicenseandSupplyAgreementsDetails"/>
  <link:definitionLink xlink:role="http://vcel.com/role/NexoBridLicenseandSupplyAgreementsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionLineItems_bc9fceef-9adf-4682-9bec-dfc3d0b2c9c6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RelatedPartyTransactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_378679e1-cdc2-452f-b7fb-f750106fb692" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_bc9fceef-9adf-4682-9bec-dfc3d0b2c9c6" xlink:to="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_378679e1-cdc2-452f-b7fb-f750106fb692" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_c6793441-fb10-47cd-8903-313dd8edb5af" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_378679e1-cdc2-452f-b7fb-f750106fb692" xlink:to="loc_srt_CounterpartyNameAxis_c6793441-fb10-47cd-8903-313dd8edb5af" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_c6793441-fb10-47cd-8903-313dd8edb5af_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_c6793441-fb10-47cd-8903-313dd8edb5af" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_c6793441-fb10-47cd-8903-313dd8edb5af_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_49ab8bef-2d9e-4f4b-b7bf-5d86ca5f9ef8" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_c6793441-fb10-47cd-8903-313dd8edb5af" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_49ab8bef-2d9e-4f4b-b7bf-5d86ca5f9ef8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_MediWoundLtdMember_a6c7133c-4585-43dc-8762-f741e0f6b090" xlink:href="vcel-20251231.xsd#vcel_MediWoundLtdMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_49ab8bef-2d9e-4f4b-b7bf-5d86ca5f9ef8" xlink:to="loc_vcel_MediWoundLtdMember_a6c7133c-4585-43dc-8762-f741e0f6b090" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_LicenseAgreementConsideration_a96c6baa-809e-46d7-954a-794e9d5c7ed1" xlink:href="vcel-20251231.xsd#vcel_LicenseAgreementConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_bc9fceef-9adf-4682-9bec-dfc3d0b2c9c6" xlink:to="loc_vcel_LicenseAgreementConsideration_a96c6baa-809e-46d7-954a-794e9d5c7ed1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_LicenseAgreementContingentConsideration_6cd48435-6134-4943-8b06-dc7dc75f1654" xlink:href="vcel-20251231.xsd#vcel_LicenseAgreementContingentConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_bc9fceef-9adf-4682-9bec-dfc3d0b2c9c6" xlink:to="loc_vcel_LicenseAgreementContingentConsideration_6cd48435-6134-4943-8b06-dc7dc75f1654" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_LicenseAgreementsMilestonePaymentsAssumedIntangibleAssets_02df1f42-2b05-44af-a7e5-9af6cc960b5d" xlink:href="vcel-20251231.xsd#vcel_LicenseAgreementsMilestonePaymentsAssumedIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_bc9fceef-9adf-4682-9bec-dfc3d0b2c9c6" xlink:to="loc_vcel_LicenseAgreementsMilestonePaymentsAssumedIntangibleAssets_02df1f42-2b05-44af-a7e5-9af6cc960b5d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireIntangibleAssets_cdc1f5d9-4c95-4c36-9190-25e1c0b2a4d4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsToAcquireIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_bc9fceef-9adf-4682-9bec-dfc3d0b2c9c6" xlink:to="loc_us-gaap_PaymentsToAcquireIntangibleAssets_cdc1f5d9-4c95-4c36-9190-25e1c0b2a4d4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_LicenseAgreementContingentConsiderationMaximum_dc36f51c-57cd-4a2f-a82d-383da6051efe" xlink:href="vcel-20251231.xsd#vcel_LicenseAgreementContingentConsiderationMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_bc9fceef-9adf-4682-9bec-dfc3d0b2c9c6" xlink:to="loc_vcel_LicenseAgreementContingentConsiderationMaximum_dc36f51c-57cd-4a2f-a82d-383da6051efe" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_LicenseAgreementInitialMilestoneSales_1569ac0c-80d2-481c-a39c-c6d1e73d54ee" xlink:href="vcel-20251231.xsd#vcel_LicenseAgreementInitialMilestoneSales"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_bc9fceef-9adf-4682-9bec-dfc3d0b2c9c6" xlink:to="loc_vcel_LicenseAgreementInitialMilestoneSales_1569ac0c-80d2-481c-a39c-c6d1e73d54ee" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_LicenseAgreementSupplyAgreementTerm_be6d63dc-238e-4728-843a-e877ef59275c" xlink:href="vcel-20251231.xsd#vcel_LicenseAgreementSupplyAgreementTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_bc9fceef-9adf-4682-9bec-dfc3d0b2c9c6" xlink:to="loc_vcel_LicenseAgreementSupplyAgreementTerm_be6d63dc-238e-4728-843a-e877ef59275c" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_LicenseAgreementSupplyAgreementRenewalTerm_ec81b2a4-3362-4317-b47d-cc4e316b98ff" xlink:href="vcel-20251231.xsd#vcel_LicenseAgreementSupplyAgreementRenewalTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_bc9fceef-9adf-4682-9bec-dfc3d0b2c9c6" xlink:to="loc_vcel_LicenseAgreementSupplyAgreementRenewalTerm_ec81b2a4-3362-4317-b47d-cc4e316b98ff" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_LicenseAgreementSupplyAgreementOptionalAdditionalTerm_fc1172e0-05c2-4ad4-84b7-258f284845bf" xlink:href="vcel-20251231.xsd#vcel_LicenseAgreementSupplyAgreementOptionalAdditionalTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_bc9fceef-9adf-4682-9bec-dfc3d0b2c9c6" xlink:to="loc_vcel_LicenseAgreementSupplyAgreementOptionalAdditionalTerm_fc1172e0-05c2-4ad4-84b7-258f284845bf" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fasb.org/us-gaap/role/eedm/ExtensibleEnumerationLists" xlink:type="simple" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-roles-2025.xsd#eedm"/>
  <link:definitionLink xlink:role="http://fasb.org/us-gaap/role/eedm/ExtensibleEnumerationLists" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization" xlink:type="arc" order="101"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://xbrl.sec.gov/ecd/role/IndividualsOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2025/ecd-2025.xsd#IndividualsOnly"/>
  <link:definitionLink xlink:role="http://xbrl.sec.gov/ecd/role/IndividualsOnly" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ecd_AllIndividualsMember" xlink:href="https://xbrl.sec.gov/ecd/2025/ecd-2025.xsd#ecd_AllIndividualsMember"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_JosephMaraMember_f1b057de-afb2-401b-86e8-b403d9d4d523" xlink:href="vcel-20251231.xsd#vcel_JosephMaraMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllIndividualsMember" xlink:to="loc_vcel_JosephMaraMember_f1b057de-afb2-401b-86e8-b403d9d4d523" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_MichaelHalpinMember_9646b4cb-73ee-4dda-bfb0-2529ee83c8a4" xlink:href="vcel-20251231.xsd#vcel_MichaelHalpinMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllIndividualsMember" xlink:to="loc_vcel_MichaelHalpinMember_9646b4cb-73ee-4dda-bfb0-2529ee83c8a4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_SeanFlynnMember_019b2249-15ca-7d04-97e7-60ec22c9b5b2" xlink:href="vcel-20251231.xsd#vcel_SeanFlynnMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllIndividualsMember" xlink:to="loc_vcel_SeanFlynnMember_019b2249-15ca-7d04-97e7-60ec22c9b5b2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_HeidiHagenMember_9911ede1-8fd3-43bf-b901-edd6795c2794" xlink:href="vcel-20251231.xsd#vcel_HeidiHagenMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllIndividualsMember" xlink:to="loc_vcel_HeidiHagenMember_9911ede1-8fd3-43bf-b901-edd6795c2794" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_JonathanSiegalMember_019b2253-8262-77ef-b6c1-4861830f053e" xlink:href="vcel-20251231.xsd#vcel_JonathanSiegalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllIndividualsMember" xlink:to="loc_vcel_JonathanSiegalMember_019b2253-8262-77ef-b6c1-4861830f053e" xlink:type="arc" order="6"/>
  </link:definitionLink>
</link:linkbase>
