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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2024 Workiva-->
<!--r:3c773174-a048-4b4a-90cf-023cf834efaf,g:693ed670-5b9e-46b7-a2fd-34e7f0adbf54-->
<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/CONDENSEDCONSOLIDATEDSTATEMENTSOFSHAREHOLDERSEQUITY" xlink:type="simple" xlink:href="vcel-20240930.xsd#CONDENSEDCONSOLIDATEDSTATEMENTSOFSHAREHOLDERSEQUITY"/>
  <link:definitionLink xlink:role="http://vcel.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFSHAREHOLDERSEQUITY" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_9492c5e8-df5d-4bb2-94ca-d4318ad165ed" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_c57e2112-7535-4ad2-8820-50d7cfeedefe" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_9492c5e8-df5d-4bb2-94ca-d4318ad165ed" xlink:to="loc_us-gaap_StatementTable_c57e2112-7535-4ad2-8820-50d7cfeedefe" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_5f9dee74-ed03-476e-a104-c5ec00fd0695" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_c57e2112-7535-4ad2-8820-50d7cfeedefe" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_5f9dee74-ed03-476e-a104-c5ec00fd0695" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_5f9dee74-ed03-476e-a104-c5ec00fd0695_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_5f9dee74-ed03-476e-a104-c5ec00fd0695" xlink:to="loc_us-gaap_EquityComponentDomain_5f9dee74-ed03-476e-a104-c5ec00fd0695_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_826a6f05-dcf2-498d-a378-b4d74e762763" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_5f9dee74-ed03-476e-a104-c5ec00fd0695" xlink:to="loc_us-gaap_EquityComponentDomain_826a6f05-dcf2-498d-a378-b4d74e762763" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_cfe3ed32-db01-4aea-ab9b-a4da629b6c64" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_826a6f05-dcf2-498d-a378-b4d74e762763" xlink:to="loc_us-gaap_CommonStockMember_cfe3ed32-db01-4aea-ab9b-a4da629b6c64" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_4895448f-6dd9-4c7a-ad0a-72038db17e3b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_826a6f05-dcf2-498d-a378-b4d74e762763" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_4895448f-6dd9-4c7a-ad0a-72038db17e3b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_7c92d149-6a43-4522-925e-83942ce64e37" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_826a6f05-dcf2-498d-a378-b4d74e762763" xlink:to="loc_us-gaap_RetainedEarningsMember_7c92d149-6a43-4522-925e-83942ce64e37" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_c74d8683-6274-44ed-9a0a-9b72a6a6a717" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_9492c5e8-df5d-4bb2-94ca-d4318ad165ed" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_c74d8683-6274-44ed-9a0a-9b72a6a6a717" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_6c9984db-2188-4728-84fc-a5926823e582" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_c74d8683-6274-44ed-9a0a-9b72a6a6a717" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_6c9984db-2188-4728-84fc-a5926823e582" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_52990e18-13e7-4999-9ac7-a0c8eec0d9f3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_c74d8683-6274-44ed-9a0a-9b72a6a6a717" xlink:to="loc_us-gaap_StockholdersEquity_52990e18-13e7-4999-9ac7-a0c8eec0d9f3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_2b95cfdd-68c9-4e13-a4e2-f672e3b1cb7d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_c74d8683-6274-44ed-9a0a-9b72a6a6a717" xlink:to="loc_us-gaap_NetIncomeLoss_2b95cfdd-68c9-4e13-a4e2-f672e3b1cb7d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_e92f8f15-2007-4ec5-8447-9dcb3a9a0ad6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_c74d8683-6274-44ed-9a0a-9b72a6a6a717" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_e92f8f15-2007-4ec5-8447-9dcb3a9a0ad6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_2125af3f-ab0c-417b-826e-53634c56da34" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_c74d8683-6274-44ed-9a0a-9b72a6a6a717" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_2125af3f-ab0c-417b-826e-53634c56da34" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_b52f5aab-ffd2-4f4a-b5fe-6a0b0758cd8e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_c74d8683-6274-44ed-9a0a-9b72a6a6a717" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_b52f5aab-ffd2-4f4a-b5fe-6a0b0758cd8e" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_444d66bf-cf01-4d7f-803d-edcf1409fe22" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_c74d8683-6274-44ed-9a0a-9b72a6a6a717" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_444d66bf-cf01-4d7f-803d-edcf1409fe22" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_a37ca80b-8fc2-48a9-b73e-bf93d6135a8c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_c74d8683-6274-44ed-9a0a-9b72a6a6a717" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_a37ca80b-8fc2-48a9-b73e-bf93d6135a8c" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures_4586bcb1-c491-4774-a617-6aa12d4ee538" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_c74d8683-6274-44ed-9a0a-9b72a6a6a717" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures_4586bcb1-c491-4774-a617-6aa12d4ee538" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_bf3fac94-49f5-4f75-b96b-2eec705a42c9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_c74d8683-6274-44ed-9a0a-9b72a6a6a717" xlink:to="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_bf3fac94-49f5-4f75-b96b-2eec705a42c9" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_e9f41b8d-dfe5-49c7-afc6-444988efcaff" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_c74d8683-6274-44ed-9a0a-9b72a6a6a717" xlink:to="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_e9f41b8d-dfe5-49c7-afc6-444988efcaff" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent_f8c758db-0939-40a4-8aa8-c6bf60131db1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_c74d8683-6274-44ed-9a0a-9b72a6a6a717" xlink:to="loc_us-gaap_OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent_f8c758db-0939-40a4-8aa8-c6bf60131db1" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_65b08a37-1049-4763-b2d2-5cfbaf67fc45" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_5ceb1a32-7e13-470d-ba82-8e7f12859490" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockholdersEquity"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://vcel.com/role/RevenueSummaryofDisaggregationofRevenueDetails" xlink:type="simple" xlink:href="vcel-20240930.xsd#RevenueSummaryofDisaggregationofRevenueDetails"/>
  <link:definitionLink xlink:role="http://vcel.com/role/RevenueSummaryofDisaggregationofRevenueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_924c92d3-541e-41f3-b6c9-ea4eb97124ed" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_bd2de4fd-a2cd-47a9-9203-9470583dc6a6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_924c92d3-541e-41f3-b6c9-ea4eb97124ed" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_bd2de4fd-a2cd-47a9-9203-9470583dc6a6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelAxis_4d86d0a4-bda1-45c9-8613-dd3f10d4302d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ContractWithCustomerSalesChannelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_bd2de4fd-a2cd-47a9-9203-9470583dc6a6" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelAxis_4d86d0a4-bda1-45c9-8613-dd3f10d4302d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelDomain_4d86d0a4-bda1-45c9-8613-dd3f10d4302d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ContractWithCustomerSalesChannelDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelAxis_4d86d0a4-bda1-45c9-8613-dd3f10d4302d" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelDomain_4d86d0a4-bda1-45c9-8613-dd3f10d4302d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelDomain_1620d22f-ae81-453e-b075-9a19e7f344b6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ContractWithCustomerSalesChannelDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelAxis_4d86d0a4-bda1-45c9-8613-dd3f10d4302d" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelDomain_1620d22f-ae81-453e-b075-9a19e7f344b6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SalesChannelThroughIntermediaryMember_542ac811-e264-4da0-b43f-340e539350cc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SalesChannelThroughIntermediaryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelDomain_1620d22f-ae81-453e-b075-9a19e7f344b6" xlink:to="loc_us-gaap_SalesChannelThroughIntermediaryMember_542ac811-e264-4da0-b43f-340e539350cc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TimeAndMaterialsContractMember_2dc97b09-3008-422e-a860-b6eed9bdab0b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TimeAndMaterialsContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelDomain_1620d22f-ae81-453e-b075-9a19e7f344b6" xlink:to="loc_us-gaap_TimeAndMaterialsContractMember_2dc97b09-3008-422e-a860-b6eed9bdab0b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_ProviderorFacilityMember_0d7b8606-2207-40b9-a607-8137849416a6" xlink:href="vcel-20240930.xsd#vcel_ProviderorFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelDomain_1620d22f-ae81-453e-b075-9a19e7f344b6" xlink:to="loc_vcel_ProviderorFacilityMember_0d7b8606-2207-40b9-a607-8137849416a6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SalesChannelDirectlyToConsumerMember_d6709ef7-662e-49b3-923f-49af4e30bde3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SalesChannelDirectlyToConsumerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelDomain_1620d22f-ae81-453e-b075-9a19e7f344b6" xlink:to="loc_us-gaap_SalesChannelDirectlyToConsumerMember_d6709ef7-662e-49b3-923f-49af4e30bde3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_5a8f0e0b-1317-4b34-a4db-ec008d265a2d" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_bd2de4fd-a2cd-47a9-9203-9470583dc6a6" xlink:to="loc_srt_ProductOrServiceAxis_5a8f0e0b-1317-4b34-a4db-ec008d265a2d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_5a8f0e0b-1317-4b34-a4db-ec008d265a2d_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_5a8f0e0b-1317-4b34-a4db-ec008d265a2d" xlink:to="loc_srt_ProductsAndServicesDomain_5a8f0e0b-1317-4b34-a4db-ec008d265a2d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_b570073e-f695-48f0-82ff-a56a003b5610" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_5a8f0e0b-1317-4b34-a4db-ec008d265a2d" xlink:to="loc_srt_ProductsAndServicesDomain_b570073e-f695-48f0-82ff-a56a003b5610" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_ImplantsMember_1390b74e-bf15-4bb1-94f5-b1389423242a" xlink:href="vcel-20240930.xsd#vcel_ImplantsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_b570073e-f695-48f0-82ff-a56a003b5610" xlink:to="loc_vcel_ImplantsMember_1390b74e-bf15-4bb1-94f5-b1389423242a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_BiopsyKitsMember_d0ecd7b9-1d1f-49c8-9271-3740962135a2" xlink:href="vcel-20240930.xsd#vcel_BiopsyKitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_b570073e-f695-48f0-82ff-a56a003b5610" xlink:to="loc_vcel_BiopsyKitsMember_d0ecd7b9-1d1f-49c8-9271-3740962135a2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_MACIImplantsAndKitsMember_c396c3ba-56e5-43d8-9f68-af09db721f39" xlink:href="vcel-20240930.xsd#vcel_MACIImplantsAndKitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_b570073e-f695-48f0-82ff-a56a003b5610" xlink:to="loc_vcel_MACIImplantsAndKitsMember_c396c3ba-56e5-43d8-9f68-af09db721f39" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_EpicelMember_a7bc909a-dbb0-4dd3-8336-6efdec8e05f7" xlink:href="vcel-20240930.xsd#vcel_EpicelMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_b570073e-f695-48f0-82ff-a56a003b5610" xlink:to="loc_vcel_EpicelMember_a7bc909a-dbb0-4dd3-8336-6efdec8e05f7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_NexoBridMember_cf289f0b-31b3-422c-a6e0-c732aa78472c" xlink:href="vcel-20240930.xsd#vcel_NexoBridMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_b570073e-f695-48f0-82ff-a56a003b5610" xlink:to="loc_vcel_NexoBridMember_cf289f0b-31b3-422c-a6e0-c732aa78472c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_03918a52-8052-4e72-8f78-c8a039843a35" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ContractWithCustomerBasisOfPricingAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_bd2de4fd-a2cd-47a9-9203-9470583dc6a6" xlink:to="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_03918a52-8052-4e72-8f78-c8a039843a35" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_03918a52-8052-4e72-8f78-c8a039843a35_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ContractWithCustomerBasisOfPricingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_03918a52-8052-4e72-8f78-c8a039843a35" xlink:to="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_03918a52-8052-4e72-8f78-c8a039843a35_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_557a460d-97de-48de-a446-c86dfaa5a1ba" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ContractWithCustomerBasisOfPricingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_03918a52-8052-4e72-8f78-c8a039843a35" xlink:to="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_557a460d-97de-48de-a446-c86dfaa5a1ba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FixedPriceContractMember_29d3204c-387c-4487-b52c-928c46dfeaef" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FixedPriceContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_557a460d-97de-48de-a446-c86dfaa5a1ba" xlink:to="loc_us-gaap_FixedPriceContractMember_29d3204c-387c-4487-b52c-928c46dfeaef" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TimeAndMaterialsContractMember_0cf22edd-756e-43c8-aba4-e3f7b1e20ea7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TimeAndMaterialsContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_557a460d-97de-48de-a446-c86dfaa5a1ba" xlink:to="loc_us-gaap_TimeAndMaterialsContractMember_0cf22edd-756e-43c8-aba4-e3f7b1e20ea7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ChangeInAccountingEstimateByTypeAxis_8a807ca2-cb7a-4803-a3be-fd8f926149d9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ChangeInAccountingEstimateByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_bd2de4fd-a2cd-47a9-9203-9470583dc6a6" xlink:to="loc_us-gaap_ChangeInAccountingEstimateByTypeAxis_8a807ca2-cb7a-4803-a3be-fd8f926149d9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ChangeInAccountingEstimateTypeDomain_8a807ca2-cb7a-4803-a3be-fd8f926149d9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ChangeInAccountingEstimateTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ChangeInAccountingEstimateByTypeAxis_8a807ca2-cb7a-4803-a3be-fd8f926149d9" xlink:to="loc_us-gaap_ChangeInAccountingEstimateTypeDomain_8a807ca2-cb7a-4803-a3be-fd8f926149d9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ChangeInAccountingEstimateTypeDomain_ac2f5b17-d85d-4ac9-99d9-6aab8099f53c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ChangeInAccountingEstimateTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ChangeInAccountingEstimateByTypeAxis_8a807ca2-cb7a-4803-a3be-fd8f926149d9" xlink:to="loc_us-gaap_ChangeInAccountingEstimateTypeDomain_ac2f5b17-d85d-4ac9-99d9-6aab8099f53c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ChangeInAccountingMethodAccountedForAsChangeInEstimateMember_84772096-86aa-4d3f-876c-3ca80d97dc5f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ChangeInAccountingMethodAccountedForAsChangeInEstimateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ChangeInAccountingEstimateTypeDomain_ac2f5b17-d85d-4ac9-99d9-6aab8099f53c" xlink:to="loc_us-gaap_ChangeInAccountingMethodAccountedForAsChangeInEstimateMember_84772096-86aa-4d3f-876c-3ca80d97dc5f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_7782a4b8-2774-44f6-833b-45911178f51a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_924c92d3-541e-41f3-b6c9-ea4eb97124ed" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_7782a4b8-2774-44f6-833b-45911178f51a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueNotFromContractWithCustomerOther_1e015a87-ec20-4196-8a91-d54da97fba0b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueNotFromContractWithCustomerOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_924c92d3-541e-41f3-b6c9-ea4eb97124ed" xlink:to="loc_us-gaap_RevenueNotFromContractWithCustomerOther_1e015a87-ec20-4196-8a91-d54da97fba0b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_9d319f6d-06c3-4690-9940-b164f4bbbb23" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_924c92d3-541e-41f3-b6c9-ea4eb97124ed" xlink:to="loc_us-gaap_Revenues_9d319f6d-06c3-4690-9940-b164f4bbbb23" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://vcel.com/role/SelectedBalanceSheetComponentsScheduleofpropertyandequipmentnetDetails" xlink:type="simple" xlink:href="vcel-20240930.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_4ecc43da-53a4-42a4-ac61-12aea442f9a5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_1b3bffb2-d70e-4a16-b390-ca3dd36fa0f6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_4ecc43da-53a4-42a4-ac61-12aea442f9a5" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_1b3bffb2-d70e-4a16-b390-ca3dd36fa0f6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_c9de2525-2296-4ff7-be95-4a600b5dc134" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_1b3bffb2-d70e-4a16-b390-ca3dd36fa0f6" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_c9de2525-2296-4ff7-be95-4a600b5dc134" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_c9de2525-2296-4ff7-be95-4a600b5dc134_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_c9de2525-2296-4ff7-be95-4a600b5dc134" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_c9de2525-2296-4ff7-be95-4a600b5dc134_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_6c24fe89-074b-43a4-8962-b6f52d25c46e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_c9de2525-2296-4ff7-be95-4a600b5dc134" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_6c24fe89-074b-43a4-8962-b6f52d25c46e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MachineryAndEquipmentMember_1901ad0b-c850-4cf9-9380-49240945eca1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MachineryAndEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_6c24fe89-074b-43a4-8962-b6f52d25c46e" xlink:to="loc_us-gaap_MachineryAndEquipmentMember_1901ad0b-c850-4cf9-9380-49240945eca1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FurnitureAndFixturesMember_bb2691bc-7a9e-4813-ba29-c6e6026fefab" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FurnitureAndFixturesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_6c24fe89-074b-43a4-8962-b6f52d25c46e" xlink:to="loc_us-gaap_FurnitureAndFixturesMember_bb2691bc-7a9e-4813-ba29-c6e6026fefab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_ComputerEquipmentAndComputerSoftwareIntangibleAssetMember_1962af96-82ae-4fe5-b7b9-e2afee64999e" xlink:href="vcel-20240930.xsd#vcel_ComputerEquipmentAndComputerSoftwareIntangibleAssetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_6c24fe89-074b-43a4-8962-b6f52d25c46e" xlink:to="loc_vcel_ComputerEquipmentAndComputerSoftwareIntangibleAssetMember_1962af96-82ae-4fe5-b7b9-e2afee64999e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseholdImprovementsMember_785a274e-ff67-4fea-be54-7ad57c4e44b9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LeaseholdImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_6c24fe89-074b-43a4-8962-b6f52d25c46e" xlink:to="loc_us-gaap_LeaseholdImprovementsMember_785a274e-ff67-4fea-be54-7ad57c4e44b9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConstructionInProgressMember_e6c3548c-6186-4648-be71-b55514520979" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConstructionInProgressMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_6c24fe89-074b-43a4-8962-b6f52d25c46e" xlink:to="loc_us-gaap_ConstructionInProgressMember_e6c3548c-6186-4648-be71-b55514520979" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_aaac7afc-a262-470f-a0b1-494e507b60f2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_4ecc43da-53a4-42a4-ac61-12aea442f9a5" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_aaac7afc-a262-470f-a0b1-494e507b60f2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization_1a668702-6f74-4d95-84c1-7573b4ac7fcb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_4ecc43da-53a4-42a4-ac61-12aea442f9a5" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization_1a668702-6f74-4d95-84c1-7573b4ac7fcb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization_b316f607-5b3b-40c0-a3b1-627e79ebd05a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_4ecc43da-53a4-42a4-ac61-12aea442f9a5" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization_b316f607-5b3b-40c0-a3b1-627e79ebd05a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_0594777f-2848-4ebc-a782-6c43a9efdb73" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_4ecc43da-53a4-42a4-ac61-12aea442f9a5" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_0594777f-2848-4ebc-a782-6c43a9efdb73" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://vcel.com/role/SelectedBalanceSheetComponentsNarrativeDetails" xlink:type="simple" xlink:href="vcel-20240930.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_4858c2b0-a16d-4c25-8a06-fa8d16ec7762" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_49cfa98b-25be-4b89-8179-3b2c24300703" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_4858c2b0-a16d-4c25-8a06-fa8d16ec7762" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_49cfa98b-25be-4b89-8179-3b2c24300703" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_94680f6e-47bc-4f59-8849-70f0cea7d1b3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_49cfa98b-25be-4b89-8179-3b2c24300703" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_94680f6e-47bc-4f59-8849-70f0cea7d1b3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_94680f6e-47bc-4f59-8849-70f0cea7d1b3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_94680f6e-47bc-4f59-8849-70f0cea7d1b3" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_94680f6e-47bc-4f59-8849-70f0cea7d1b3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_feeaa95f-c8ca-4fcb-bac7-2ad44164556a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_94680f6e-47bc-4f59-8849-70f0cea7d1b3" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_feeaa95f-c8ca-4fcb-bac7-2ad44164556a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LicensingAgreementsMember_32453d4a-d9f7-45bc-b1ec-686af891ea3e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LicensingAgreementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_feeaa95f-c8ca-4fcb-bac7-2ad44164556a" xlink:to="loc_us-gaap_LicensingAgreementsMember_32453d4a-d9f7-45bc-b1ec-686af891ea3e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_ba2265e7-160b-4dd7-873d-ab5eded2e9c3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Depreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_4858c2b0-a16d-4c25-8a06-fa8d16ec7762" xlink:to="loc_us-gaap_Depreciation_ba2265e7-160b-4dd7-873d-ab5eded2e9c3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_e66b6866-da1c-457e-91af-fd9cbaec97db" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_4858c2b0-a16d-4c25-8a06-fa8d16ec7762" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_e66b6866-da1c-457e-91af-fd9cbaec97db" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://vcel.com/role/SelectedBalanceSheetComponentsScheduleoffinitelivedintangibleassetsDetails" xlink:type="simple" xlink:href="vcel-20240930.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_b4e1c4a6-aab1-470e-81a1-d89315a1d20f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_dacc174e-e2c6-4fc3-9629-e8eab607ee0e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_b4e1c4a6-aab1-470e-81a1-d89315a1d20f" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_dacc174e-e2c6-4fc3-9629-e8eab607ee0e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_a22dc802-f1c1-455c-a4e1-160e9535b893" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_dacc174e-e2c6-4fc3-9629-e8eab607ee0e" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_a22dc802-f1c1-455c-a4e1-160e9535b893" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_a22dc802-f1c1-455c-a4e1-160e9535b893_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_a22dc802-f1c1-455c-a4e1-160e9535b893" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_a22dc802-f1c1-455c-a4e1-160e9535b893_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_af9c771c-e38d-4186-922f-f7125ee2fb24" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_a22dc802-f1c1-455c-a4e1-160e9535b893" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_af9c771c-e38d-4186-922f-f7125ee2fb24" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LicensingAgreementsMember_668f4f36-d8f4-4ad0-82a1-7ed5ce7a7fe4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LicensingAgreementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_af9c771c-e38d-4186-922f-f7125ee2fb24" xlink:to="loc_us-gaap_LicensingAgreementsMember_668f4f36-d8f4-4ad0-82a1-7ed5ce7a7fe4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_bc542893-8115-483b-812f-5bd42e008f54" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_b4e1c4a6-aab1-470e-81a1-d89315a1d20f" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_bc542893-8115-483b-812f-5bd42e008f54" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_039718f9-1235-4980-836a-3ec5b71c8a80" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_b4e1c4a6-aab1-470e-81a1-d89315a1d20f" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_039718f9-1235-4980-836a-3ec5b71c8a80" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_8d4fe513-fa3f-4ec6-b1ac-fbc298f7b392" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_b4e1c4a6-aab1-470e-81a1-d89315a1d20f" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_8d4fe513-fa3f-4ec6-b1ac-fbc298f7b392" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_7817f3aa-8cef-4be4-9a1f-90dd01250593" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_b4e1c4a6-aab1-470e-81a1-d89315a1d20f" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_7817f3aa-8cef-4be4-9a1f-90dd01250593" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://vcel.com/role/SelectedBalanceSheetComponentsScheduleoffinitelivedintangibleassetsfutureamortizationexpenseDetails" xlink:type="simple" xlink:href="vcel-20240930.xsd#SelectedBalanceSheetComponentsScheduleoffinitelivedintangibleassetsfutureamortizationexpenseDetails"/>
  <link:definitionLink xlink:role="http://vcel.com/role/SelectedBalanceSheetComponentsScheduleoffinitelivedintangibleassetsfutureamortizationexpenseDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_4490ba79-ec49-460e-914a-22ad1e261da9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_811ca07b-e976-4b28-8122-d11720f634ac" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_4490ba79-ec49-460e-914a-22ad1e261da9" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_811ca07b-e976-4b28-8122-d11720f634ac" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_bd40a744-2424-45e3-811c-8538ce4a0e4b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_811ca07b-e976-4b28-8122-d11720f634ac" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_bd40a744-2424-45e3-811c-8538ce4a0e4b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_bd40a744-2424-45e3-811c-8538ce4a0e4b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_bd40a744-2424-45e3-811c-8538ce4a0e4b" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_bd40a744-2424-45e3-811c-8538ce4a0e4b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_86f647ae-c523-4ef9-a144-b00a7e49b377" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_bd40a744-2424-45e3-811c-8538ce4a0e4b" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_86f647ae-c523-4ef9-a144-b00a7e49b377" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LicensingAgreementsMember_f41ada26-7f31-4cfc-9f25-e7f208928cb8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LicensingAgreementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_86f647ae-c523-4ef9-a144-b00a7e49b377" xlink:to="loc_us-gaap_LicensingAgreementsMember_f41ada26-7f31-4cfc-9f25-e7f208928cb8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear_b46123ab-03de-460a-925e-d86f1d35d556" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_4490ba79-ec49-460e-914a-22ad1e261da9" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear_b46123ab-03de-460a-925e-d86f1d35d556" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_3af12b79-a09d-49f7-a25d-5cf0470a2163" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_4490ba79-ec49-460e-914a-22ad1e261da9" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_3af12b79-a09d-49f7-a25d-5cf0470a2163" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_3412da34-e927-4080-9ab5-9012f4fd5217" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_4490ba79-ec49-460e-914a-22ad1e261da9" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_3412da34-e927-4080-9ab5-9012f4fd5217" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_a5b795e2-8c89-4f6c-b3ba-b04037afaeb0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_4490ba79-ec49-460e-914a-22ad1e261da9" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_a5b795e2-8c89-4f6c-b3ba-b04037afaeb0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_07969c3c-979b-451f-b283-747c74b38d97" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_4490ba79-ec49-460e-914a-22ad1e261da9" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_07969c3c-979b-451f-b283-747c74b38d97" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_FiniteLivedIntangibleAssetExpectedAmortizationAfterYearFour_cf290ead-d438-44ec-96d5-32faa592b73e" xlink:href="vcel-20240930.xsd#vcel_FiniteLivedIntangibleAssetExpectedAmortizationAfterYearFour"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_4490ba79-ec49-460e-914a-22ad1e261da9" xlink:to="loc_vcel_FiniteLivedIntangibleAssetExpectedAmortizationAfterYearFour_cf290ead-d438-44ec-96d5-32faa592b73e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_9fc80e26-b767-4cb7-b4c7-3a4c0f94b2bc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_4490ba79-ec49-460e-914a-22ad1e261da9" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_9fc80e26-b767-4cb7-b4c7-3a4c0f94b2bc" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://vcel.com/role/LeasesNarrativeDetails" xlink:type="simple" xlink:href="vcel-20240930.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_88737b43-340e-43bd-866a-e7e9d530f168" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LesseeLeaseDescriptionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionTable_cf9a67e1-9147-4135-946d-6c34babe1594" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LesseeLeaseDescriptionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_88737b43-340e-43bd-866a-e7e9d530f168" xlink:to="loc_us-gaap_LesseeLeaseDescriptionTable_cf9a67e1-9147-4135-946d-6c34babe1594" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_de53bab9-c42e-4de2-8daa-0188b221644b" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_cf9a67e1-9147-4135-946d-6c34babe1594" xlink:to="loc_srt_RangeAxis_de53bab9-c42e-4de2-8daa-0188b221644b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_de53bab9-c42e-4de2-8daa-0188b221644b_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_de53bab9-c42e-4de2-8daa-0188b221644b" xlink:to="loc_srt_RangeMember_de53bab9-c42e-4de2-8daa-0188b221644b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_ee1641bc-64e3-46e0-96b3-697a176506fb" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_de53bab9-c42e-4de2-8daa-0188b221644b" xlink:to="loc_srt_RangeMember_ee1641bc-64e3-46e0-96b3-697a176506fb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_e5f5aac5-3ea2-4f04-8536-62cc13c30679" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_ee1641bc-64e3-46e0-96b3-697a176506fb" xlink:to="loc_srt_MinimumMember_e5f5aac5-3ea2-4f04-8536-62cc13c30679" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_34f14690-2997-45d7-bea1-00a3fb038c4f" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_ee1641bc-64e3-46e0-96b3-697a176506fb" xlink:to="loc_srt_MaximumMember_34f14690-2997-45d7-bea1-00a3fb038c4f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis_a9ce0c54-2b9e-4d70-8ff1-ebf5c37b22c7" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_cf9a67e1-9147-4135-946d-6c34babe1594" xlink:to="loc_srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis_a9ce0c54-2b9e-4d70-8ff1-ebf5c37b22c7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain_a9ce0c54-2b9e-4d70-8ff1-ebf5c37b22c7_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis_a9ce0c54-2b9e-4d70-8ff1-ebf5c37b22c7" xlink:to="loc_srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain_a9ce0c54-2b9e-4d70-8ff1-ebf5c37b22c7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain_609111f5-c066-42ea-8925-2436c5684d3f" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis_a9ce0c54-2b9e-4d70-8ff1-ebf5c37b22c7" xlink:to="loc_srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain_609111f5-c066-42ea-8925-2436c5684d3f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_A25NetworkDriveBurlingtonMassachusettsMember_402a2378-ebd1-4a4f-9474-96706c6da57b" xlink:href="vcel-20240930.xsd#vcel_A25NetworkDriveBurlingtonMassachusettsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain_609111f5-c066-42ea-8925-2436c5684d3f" xlink:to="loc_vcel_A25NetworkDriveBurlingtonMassachusettsMember_402a2378-ebd1-4a4f-9474-96706c6da57b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AreaOfRealEstateProperty_1104273f-3a53-432f-9ae9-77bffc12a1b1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AreaOfRealEstateProperty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_88737b43-340e-43bd-866a-e7e9d530f168" xlink:to="loc_us-gaap_AreaOfRealEstateProperty_1104273f-3a53-432f-9ae9-77bffc12a1b1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_EscrowDepositPercentContributed_bab2ee74-4c4f-4a5c-a871-4434507c2afb" xlink:href="vcel-20240930.xsd#vcel_EscrowDepositPercentContributed"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_88737b43-340e-43bd-866a-e7e9d530f168" xlink:to="loc_vcel_EscrowDepositPercentContributed_bab2ee74-4c4f-4a5c-a871-4434507c2afb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EscrowDeposit_dbb1bed8-d8ab-4c4b-a026-91bb268e55d9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EscrowDeposit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_88737b43-340e-43bd-866a-e7e9d530f168" xlink:to="loc_us-gaap_EscrowDeposit_dbb1bed8-d8ab-4c4b-a026-91bb268e55d9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseTermOfContract_6716e635-0319-4957-9b21-ea87631d617c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LesseeOperatingLeaseTermOfContract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_88737b43-340e-43bd-866a-e7e9d530f168" xlink:to="loc_us-gaap_LesseeOperatingLeaseTermOfContract_6716e635-0319-4957-9b21-ea87631d617c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_LesseeOperatingLeaseNumberOfRenewalOptions_a9e47f88-b697-4ddd-88d9-aea128fe6a70" xlink:href="vcel-20240930.xsd#vcel_LesseeOperatingLeaseNumberOfRenewalOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_88737b43-340e-43bd-866a-e7e9d530f168" xlink:to="loc_vcel_LesseeOperatingLeaseNumberOfRenewalOptions_a9e47f88-b697-4ddd-88d9-aea128fe6a70" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_LeaseOptionToExtendTerm_26cf9b22-4b17-4d5b-84bc-fa302eb628cc" xlink:href="vcel-20240930.xsd#vcel_LeaseOptionToExtendTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_88737b43-340e-43bd-866a-e7e9d530f168" xlink:to="loc_vcel_LeaseOptionToExtendTerm_26cf9b22-4b17-4d5b-84bc-fa302eb628cc" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_LesseeOperatingLeaseAnnualLeasePerSquareFoot_a7c1faae-1dc1-4bb6-b527-cff6e7931b01" xlink:href="vcel-20240930.xsd#vcel_LesseeOperatingLeaseAnnualLeasePerSquareFoot"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_88737b43-340e-43bd-866a-e7e9d530f168" xlink:to="loc_vcel_LesseeOperatingLeaseAnnualLeasePerSquareFoot_a7c1faae-1dc1-4bb6-b527-cff6e7931b01" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_LesseeOperatingLeaseAnnualLeaseIncreaseLimitPercentage_29b2205e-f0ed-4176-9b2d-2e5d5acd5aab" xlink:href="vcel-20240930.xsd#vcel_LesseeOperatingLeaseAnnualLeaseIncreaseLimitPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_88737b43-340e-43bd-866a-e7e9d530f168" xlink:to="loc_vcel_LesseeOperatingLeaseAnnualLeaseIncreaseLimitPercentage_29b2205e-f0ed-4176-9b2d-2e5d5acd5aab" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_LesseeOperatingLeaseMonthlyContractualPayments_06ea7e20-e7b8-4389-8379-c28f588fc1ed" xlink:href="vcel-20240930.xsd#vcel_LesseeOperatingLeaseMonthlyContractualPayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_88737b43-340e-43bd-866a-e7e9d530f168" xlink:to="loc_vcel_LesseeOperatingLeaseMonthlyContractualPayments_06ea7e20-e7b8-4389-8379-c28f588fc1ed" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_LesseeOperatingLeaseTenantImprovementAllowancePerSquareFoot_68a5d1af-0e77-470e-bd92-cbd27f0805b1" xlink:href="vcel-20240930.xsd#vcel_LesseeOperatingLeaseTenantImprovementAllowancePerSquareFoot"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_88737b43-340e-43bd-866a-e7e9d530f168" xlink:to="loc_vcel_LesseeOperatingLeaseTenantImprovementAllowancePerSquareFoot_68a5d1af-0e77-470e-bd92-cbd27f0805b1" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_LesseeOperatingLeaseTenantImprovementAllowance_034b6a2a-473d-4fab-be53-1582bfce48f1" xlink:href="vcel-20240930.xsd#vcel_LesseeOperatingLeaseTenantImprovementAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_88737b43-340e-43bd-866a-e7e9d530f168" xlink:to="loc_vcel_LesseeOperatingLeaseTenantImprovementAllowance_034b6a2a-473d-4fab-be53-1582bfce48f1" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_d80b88d5-f1b5-421f-945a-25b1c59c7e67" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingLeaseRightOfUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_88737b43-340e-43bd-866a-e7e9d530f168" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_d80b88d5-f1b5-421f-945a-25b1c59c7e67" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiability_11791186-954a-4762-bbea-849cca6fb366" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_88737b43-340e-43bd-866a-e7e9d530f168" xlink:to="loc_us-gaap_OperatingLeaseLiability_11791186-954a-4762-bbea-849cca6fb366" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_OperatingLeaseLiabilityIncrementalBorrowingRate_3e80ca91-7b71-4530-98c3-ad44906da5d6" xlink:href="vcel-20240930.xsd#vcel_OperatingLeaseLiabilityIncrementalBorrowingRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_88737b43-340e-43bd-866a-e7e9d530f168" xlink:to="loc_vcel_OperatingLeaseLiabilityIncrementalBorrowingRate_3e80ca91-7b71-4530-98c3-ad44906da5d6" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_LesseeOperatingLeaseTermOfContractInclusiveOfFreeRent_d668fd7e-3525-4352-97d2-c86a4abd748d" xlink:href="vcel-20240930.xsd#vcel_LesseeOperatingLeaseTermOfContractInclusiveOfFreeRent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_88737b43-340e-43bd-866a-e7e9d530f168" xlink:to="loc_vcel_LesseeOperatingLeaseTermOfContractInclusiveOfFreeRent_d668fd7e-3525-4352-97d2-c86a4abd748d" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_LetterOfCreditCashDeposit_c078c917-0322-4286-b44b-992c2349af52" xlink:href="vcel-20240930.xsd#vcel_LetterOfCreditCashDeposit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_88737b43-340e-43bd-866a-e7e9d530f168" xlink:to="loc_vcel_LetterOfCreditCashDeposit_c078c917-0322-4286-b44b-992c2349af52" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_LetterOfCreditCashDepositLeaseYearThree_9a557b70-440d-4677-803a-630b71a0c4d8" xlink:href="vcel-20240930.xsd#vcel_LetterOfCreditCashDepositLeaseYearThree"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_88737b43-340e-43bd-866a-e7e9d530f168" xlink:to="loc_vcel_LetterOfCreditCashDepositLeaseYearThree_9a557b70-440d-4677-803a-630b71a0c4d8" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_LetterOfCreditCashDepositLeaseYearFour_b2ced7e1-9d84-4670-a0b1-613e08f26d9f" xlink:href="vcel-20240930.xsd#vcel_LetterOfCreditCashDepositLeaseYearFour"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_88737b43-340e-43bd-866a-e7e9d530f168" xlink:to="loc_vcel_LetterOfCreditCashDepositLeaseYearFour_b2ced7e1-9d84-4670-a0b1-613e08f26d9f" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermLeaseCost_5e0dfef2-cc47-4574-b44e-69765492ddb6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShortTermLeaseCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_88737b43-340e-43bd-866a-e7e9d530f168" xlink:to="loc_us-gaap_ShortTermLeaseCost_5e0dfef2-cc47-4574-b44e-69765492ddb6" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseExpense_9111ff0a-a29e-4eef-8bcc-e291e340ba78" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingLeaseExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_88737b43-340e-43bd-866a-e7e9d530f168" xlink:to="loc_us-gaap_OperatingLeaseExpense_9111ff0a-a29e-4eef-8bcc-e291e340ba78" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseInterestExpense_3b7e8d5a-b896-49c5-b3f5-569311f8d20b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinanceLeaseInterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_88737b43-340e-43bd-866a-e7e9d530f168" xlink:to="loc_us-gaap_FinanceLeaseInterestExpense_3b7e8d5a-b896-49c5-b3f5-569311f8d20b" xlink:type="arc" order="20"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://vcel.com/role/InvestmentsDetails" xlink:type="simple" xlink:href="vcel-20240930.xsd#InvestmentsDetails"/>
  <link:definitionLink xlink:role="http://vcel.com/role/InvestmentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MarketableSecuritiesLineItems_2e3cfe9f-508c-46a9-9aa8-05f96fef418d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MarketableSecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MarketableSecuritiesTable_7fc05c4d-e2aa-4dda-8b2f-99c9dc93937d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MarketableSecuritiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_2e3cfe9f-508c-46a9-9aa8-05f96fef418d" xlink:to="loc_us-gaap_MarketableSecuritiesTable_7fc05c4d-e2aa-4dda-8b2f-99c9dc93937d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_225e77e5-801f-4750-b6f8-e85216aa10f4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_MarketableSecuritiesTable_7fc05c4d-e2aa-4dda-8b2f-99c9dc93937d" xlink:to="loc_us-gaap_FinancialInstrumentAxis_225e77e5-801f-4750-b6f8-e85216aa10f4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_225e77e5-801f-4750-b6f8-e85216aa10f4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_225e77e5-801f-4750-b6f8-e85216aa10f4" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_225e77e5-801f-4750-b6f8-e85216aa10f4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b5925e1e-4c40-4545-90b1-2081cc6e029f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_225e77e5-801f-4750-b6f8-e85216aa10f4" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b5925e1e-4c40-4545-90b1-2081cc6e029f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPaperMember_88ce63c9-5d95-475b-9590-410f1c6bf345" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommercialPaperMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b5925e1e-4c40-4545-90b1-2081cc6e029f" xlink:to="loc_us-gaap_CommercialPaperMember_88ce63c9-5d95-475b-9590-410f1c6bf345" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_21389a73-6a65-401a-a1dc-4a655f7351c0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b5925e1e-4c40-4545-90b1-2081cc6e029f" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_21389a73-6a65-401a-a1dc-4a655f7351c0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentDebtSecuritiesMember_dd311e39-e7d6-490d-9f0a-1bf62d970b05" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_USGovernmentDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b5925e1e-4c40-4545-90b1-2081cc6e029f" xlink:to="loc_us-gaap_USGovernmentDebtSecuritiesMember_dd311e39-e7d6-490d-9f0a-1bf62d970b05" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_b2565a91-8123-4be0-a691-3f2e07041e85" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_USGovernmentAgenciesDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b5925e1e-4c40-4545-90b1-2081cc6e029f" xlink:to="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_b2565a91-8123-4be0-a691-3f2e07041e85" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_24eb1927-eee9-4a7d-a0ac-5f17366ebd39" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_MarketableSecuritiesTable_7fc05c4d-e2aa-4dda-8b2f-99c9dc93937d" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_24eb1927-eee9-4a7d-a0ac-5f17366ebd39" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_24eb1927-eee9-4a7d-a0ac-5f17366ebd39_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_24eb1927-eee9-4a7d-a0ac-5f17366ebd39" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_24eb1927-eee9-4a7d-a0ac-5f17366ebd39_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_886f974a-765b-42ba-ae3d-eee0ef5053ab" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_24eb1927-eee9-4a7d-a0ac-5f17366ebd39" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_886f974a-765b-42ba-ae3d-eee0ef5053ab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermInvestmentsMember_a10809a4-356d-474e-a719-9cb28f7a19c0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShortTermInvestmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_886f974a-765b-42ba-ae3d-eee0ef5053ab" xlink:to="loc_us-gaap_ShortTermInvestmentsMember_a10809a4-356d-474e-a719-9cb28f7a19c0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_LongtermInvestmentsMember_89c1d61f-9d6d-4919-8955-4c509c0f7931" xlink:href="vcel-20240930.xsd#vcel_LongtermInvestmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_886f974a-765b-42ba-ae3d-eee0ef5053ab" xlink:to="loc_vcel_LongtermInvestmentsMember_89c1d61f-9d6d-4919-8955-4c509c0f7931" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_4e4bf1b5-b825-4d08-91ab-ffef25669a33" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_2e3cfe9f-508c-46a9-9aa8-05f96fef418d" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_4e4bf1b5-b825-4d08-91ab-ffef25669a33" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_8a5d3356-d097-436f-8e88-f1088c271b86" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_2e3cfe9f-508c-46a9-9aa8-05f96fef418d" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_8a5d3356-d097-436f-8e88-f1088c271b86" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_adb72c08-581c-4d43-9494-9560da8218d7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_2e3cfe9f-508c-46a9-9aa8-05f96fef418d" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_adb72c08-581c-4d43-9494-9560da8218d7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLoss_7ff011ef-d4a0-450b-a3d7-2d81da17e797" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_2e3cfe9f-508c-46a9-9aa8-05f96fef418d" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLoss_7ff011ef-d4a0-450b-a3d7-2d81da17e797" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_2e88a463-9b41-4381-9bf5-8b95f2dde2a3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_2e3cfe9f-508c-46a9-9aa8-05f96fef418d" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_2e88a463-9b41-4381-9bf5-8b95f2dde2a3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_DebtSecuritiesAvailableForSaleContractualMaturityPeriod_7c344211-e154-4970-9e8c-6e5bc6f47b39" xlink:href="vcel-20240930.xsd#vcel_DebtSecuritiesAvailableForSaleContractualMaturityPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_2e3cfe9f-508c-46a9-9aa8-05f96fef418d" xlink:to="loc_vcel_DebtSecuritiesAvailableForSaleContractualMaturityPeriod_7c344211-e154-4970-9e8c-6e5bc6f47b39" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetImpairmentCharges_7dbe5bd6-c101-4483-9204-89a61d904bb9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AssetImpairmentCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MarketableSecuritiesLineItems_2e3cfe9f-508c-46a9-9aa8-05f96fef418d" xlink:to="loc_us-gaap_AssetImpairmentCharges_7dbe5bd6-c101-4483-9204-89a61d904bb9" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://vcel.com/role/FairValueMeasurementsDetails" xlink:type="simple" xlink:href="vcel-20240930.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_7b3ba2c6-f4d1-4ca2-9f7e-d25d300ad056" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_301ffde1-8c04-49f9-91ae-981fe83d2015" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_7b3ba2c6-f4d1-4ca2-9f7e-d25d300ad056" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_301ffde1-8c04-49f9-91ae-981fe83d2015" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_eb93e70c-0d88-4b45-b327-2ba323b32a1b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_301ffde1-8c04-49f9-91ae-981fe83d2015" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_eb93e70c-0d88-4b45-b327-2ba323b32a1b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_eb93e70c-0d88-4b45-b327-2ba323b32a1b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_eb93e70c-0d88-4b45-b327-2ba323b32a1b" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_eb93e70c-0d88-4b45-b327-2ba323b32a1b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_e7f1a12d-4c10-4707-83c4-e9170ea3e7f5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_eb93e70c-0d88-4b45-b327-2ba323b32a1b" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_e7f1a12d-4c10-4707-83c4-e9170ea3e7f5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_959f815d-5fc8-458b-a9fd-fc1a70ef0d8d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_e7f1a12d-4c10-4707-83c4-e9170ea3e7f5" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_959f815d-5fc8-458b-a9fd-fc1a70ef0d8d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAxis_d4bdb4b8-ab5f-41da-a864-933c93c84c28" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashAndCashEquivalentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_301ffde1-8c04-49f9-91ae-981fe83d2015" xlink:to="loc_us-gaap_CashAndCashEquivalentsAxis_d4bdb4b8-ab5f-41da-a864-933c93c84c28" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_d4bdb4b8-ab5f-41da-a864-933c93c84c28_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CashAndCashEquivalentsAxis_d4bdb4b8-ab5f-41da-a864-933c93c84c28" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_d4bdb4b8-ab5f-41da-a864-933c93c84c28_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_9bb19684-9360-4bcd-85bf-b774305cee4d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CashAndCashEquivalentsAxis_d4bdb4b8-ab5f-41da-a864-933c93c84c28" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_9bb19684-9360-4bcd-85bf-b774305cee4d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MoneyMarketFundsMember_2b02e306-3d2b-4861-858a-c738a384ef49" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MoneyMarketFundsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_9bb19684-9360-4bcd-85bf-b774305cee4d" xlink:to="loc_us-gaap_MoneyMarketFundsMember_2b02e306-3d2b-4861-858a-c738a384ef49" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_b677717e-36a0-486a-9e46-972fd0f6b188" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_301ffde1-8c04-49f9-91ae-981fe83d2015" xlink:to="loc_us-gaap_FinancialInstrumentAxis_b677717e-36a0-486a-9e46-972fd0f6b188" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b677717e-36a0-486a-9e46-972fd0f6b188_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_b677717e-36a0-486a-9e46-972fd0f6b188" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b677717e-36a0-486a-9e46-972fd0f6b188_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_dcb4583d-994a-48da-bedc-019a969d2c32" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_b677717e-36a0-486a-9e46-972fd0f6b188" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_dcb4583d-994a-48da-bedc-019a969d2c32" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPaperMember_765c9e28-e3ce-4ef3-99a4-f8cab1483eaf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommercialPaperMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_dcb4583d-994a-48da-bedc-019a969d2c32" xlink:to="loc_us-gaap_CommercialPaperMember_765c9e28-e3ce-4ef3-99a4-f8cab1483eaf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNoteSecuritiesMember_a7051c25-9e20-4d63-8426-f26a8f4679e9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CorporateNoteSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_dcb4583d-994a-48da-bedc-019a969d2c32" xlink:to="loc_us-gaap_CorporateNoteSecuritiesMember_a7051c25-9e20-4d63-8426-f26a8f4679e9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_8339f829-2882-4d5d-92c3-2daa417a0f81" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_USGovernmentAgenciesDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_dcb4583d-994a-48da-bedc-019a969d2c32" xlink:to="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_8339f829-2882-4d5d-92c3-2daa417a0f81" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentDebtSecuritiesMember_951b2ed9-f1d8-4675-a21c-269dd306db60" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_USGovernmentDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_dcb4583d-994a-48da-bedc-019a969d2c32" xlink:to="loc_us-gaap_USGovernmentDebtSecuritiesMember_951b2ed9-f1d8-4675-a21c-269dd306db60" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_7ee841be-475f-4f2c-ab95-09e438928a8a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_301ffde1-8c04-49f9-91ae-981fe83d2015" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_7ee841be-475f-4f2c-ab95-09e438928a8a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7ee841be-475f-4f2c-ab95-09e438928a8a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_7ee841be-475f-4f2c-ab95-09e438928a8a" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7ee841be-475f-4f2c-ab95-09e438928a8a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_9d8f5e40-205e-492a-a378-b1888326eb90" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_7ee841be-475f-4f2c-ab95-09e438928a8a" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_9d8f5e40-205e-492a-a378-b1888326eb90" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_91e00600-b920-4652-80ef-66702aed3908" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_9d8f5e40-205e-492a-a378-b1888326eb90" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_91e00600-b920-4652-80ef-66702aed3908" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_048ce6af-a60d-4933-bc59-b3b34fb68c73" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_9d8f5e40-205e-492a-a378-b1888326eb90" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_048ce6af-a60d-4933-bc59-b3b34fb68c73" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_57c5ee67-8f50-4250-9a0c-81da30a69b0b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_9d8f5e40-205e-492a-a378-b1888326eb90" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_57c5ee67-8f50-4250-9a0c-81da30a69b0b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_e43952a6-9e5f-42e0-a7ec-52cb3bae362f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_301ffde1-8c04-49f9-91ae-981fe83d2015" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_e43952a6-9e5f-42e0-a7ec-52cb3bae362f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_e43952a6-9e5f-42e0-a7ec-52cb3bae362f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_e43952a6-9e5f-42e0-a7ec-52cb3bae362f" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_e43952a6-9e5f-42e0-a7ec-52cb3bae362f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_97782e1a-03c7-4ee6-92d9-6f14f0e9ab51" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_e43952a6-9e5f-42e0-a7ec-52cb3bae362f" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_97782e1a-03c7-4ee6-92d9-6f14f0e9ab51" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsMember_24b22f3b-b7f2-4375-b86a-9bcc65eb2304" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_97782e1a-03c7-4ee6-92d9-6f14f0e9ab51" xlink:to="loc_us-gaap_CashAndCashEquivalentsMember_24b22f3b-b7f2-4375-b86a-9bcc65eb2304" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_53e27439-bc8e-4e6f-bd2c-c37a00cdd260" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_7b3ba2c6-f4d1-4ca2-9f7e-d25d300ad056" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_53e27439-bc8e-4e6f-bd2c-c37a00cdd260" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_7e3c9bee-bb6e-4bb2-ae06-72e1bebd79d6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_7b3ba2c6-f4d1-4ca2-9f7e-d25d300ad056" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_7e3c9bee-bb6e-4bb2-ae06-72e1bebd79d6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_3e6c15e5-2e03-450c-970c-7fadb5117051" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_7b3ba2c6-f4d1-4ca2-9f7e-d25d300ad056" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_3e6c15e5-2e03-450c-970c-7fadb5117051" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://vcel.com/role/RevolvingCreditAgreementDetails" xlink:type="simple" xlink:href="vcel-20240930.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_4fbd2ecc-d66d-44ef-af6c-e7761e727d62" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_8562552e-aaef-4a0b-9b58-2769b4df8771" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4fbd2ecc-d66d-44ef-af6c-e7761e727d62" xlink:to="loc_us-gaap_DebtInstrumentTable_8562552e-aaef-4a0b-9b58-2769b4df8771" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_6aa3fae1-2024-42d7-99bc-2ed714065048" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_8562552e-aaef-4a0b-9b58-2769b4df8771" xlink:to="loc_us-gaap_CreditFacilityAxis_6aa3fae1-2024-42d7-99bc-2ed714065048" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_6aa3fae1-2024-42d7-99bc-2ed714065048_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_6aa3fae1-2024-42d7-99bc-2ed714065048" xlink:to="loc_us-gaap_CreditFacilityDomain_6aa3fae1-2024-42d7-99bc-2ed714065048_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_ce3939cc-b869-4f82-ad5a-c8e06c71991a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_6aa3fae1-2024-42d7-99bc-2ed714065048" xlink:to="loc_us-gaap_CreditFacilityDomain_ce3939cc-b869-4f82-ad5a-c8e06c71991a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_698d5610-8437-490a-9de1-c0c8d210825e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_ce3939cc-b869-4f82-ad5a-c8e06c71991a" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_698d5610-8437-490a-9de1-c0c8d210825e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LetterOfCreditMember_00b1bb8e-dc87-45b2-a6f2-5341004d2ccd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LetterOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_ce3939cc-b869-4f82-ad5a-c8e06c71991a" xlink:to="loc_us-gaap_LetterOfCreditMember_00b1bb8e-dc87-45b2-a6f2-5341004d2ccd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_c2d17c18-f12f-4df3-a3c3-974ef88e89c7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_8562552e-aaef-4a0b-9b58-2769b4df8771" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_c2d17c18-f12f-4df3-a3c3-974ef88e89c7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_c2d17c18-f12f-4df3-a3c3-974ef88e89c7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_c2d17c18-f12f-4df3-a3c3-974ef88e89c7" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_c2d17c18-f12f-4df3-a3c3-974ef88e89c7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_276e082c-fda3-49d3-a23f-7d69af6005d2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_c2d17c18-f12f-4df3-a3c3-974ef88e89c7" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_276e082c-fda3-49d3-a23f-7d69af6005d2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_9ba6c23d-39ba-4803-bcbe-7bcaf0090ef4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_276e082c-fda3-49d3-a23f-7d69af6005d2" xlink:to="loc_us-gaap_LineOfCreditMember_9ba6c23d-39ba-4803-bcbe-7bcaf0090ef4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_3a6e7e43-6eaa-4e7f-b2bb-39266caeb60a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_VariableRateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_8562552e-aaef-4a0b-9b58-2769b4df8771" xlink:to="loc_us-gaap_VariableRateAxis_3a6e7e43-6eaa-4e7f-b2bb-39266caeb60a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_3a6e7e43-6eaa-4e7f-b2bb-39266caeb60a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_3a6e7e43-6eaa-4e7f-b2bb-39266caeb60a" xlink:to="loc_us-gaap_VariableRateDomain_3a6e7e43-6eaa-4e7f-b2bb-39266caeb60a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_93ee9341-522b-4ddf-96b9-273984b116ee" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_3a6e7e43-6eaa-4e7f-b2bb-39266caeb60a" xlink:to="loc_us-gaap_VariableRateDomain_93ee9341-522b-4ddf-96b9-273984b116ee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredOvernightFinancingRateSofrMember_29d09c21-d68c-4d95-9537-65a19f42c0f7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuredOvernightFinancingRateSofrMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_93ee9341-522b-4ddf-96b9-273984b116ee" xlink:to="loc_us-gaap_SecuredOvernightFinancingRateSofrMember_29d09c21-d68c-4d95-9537-65a19f42c0f7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BaseRateMember_c69b5458-1309-4247-aaec-be2d12b55e30" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BaseRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_93ee9341-522b-4ddf-96b9-273984b116ee" xlink:to="loc_us-gaap_BaseRateMember_c69b5458-1309-4247-aaec-be2d12b55e30" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_4c7b5e49-c644-4a05-b08a-eb2659918f93" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_8562552e-aaef-4a0b-9b58-2769b4df8771" xlink:to="loc_srt_RangeAxis_4c7b5e49-c644-4a05-b08a-eb2659918f93" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_4c7b5e49-c644-4a05-b08a-eb2659918f93_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_4c7b5e49-c644-4a05-b08a-eb2659918f93" xlink:to="loc_srt_RangeMember_4c7b5e49-c644-4a05-b08a-eb2659918f93_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_4bf8ffe0-a496-4e62-ba28-cc13ef2a78ab" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_4c7b5e49-c644-4a05-b08a-eb2659918f93" xlink:to="loc_srt_RangeMember_4bf8ffe0-a496-4e62-ba28-cc13ef2a78ab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_bbf8b5bf-1cd8-4ec0-8e87-68ebd2e61fc8" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_4bf8ffe0-a496-4e62-ba28-cc13ef2a78ab" xlink:to="loc_srt_MinimumMember_bbf8b5bf-1cd8-4ec0-8e87-68ebd2e61fc8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_291c970d-6bcf-4ad7-9d88-d698f8c0c533" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_4bf8ffe0-a496-4e62-ba28-cc13ef2a78ab" xlink:to="loc_srt_MaximumMember_291c970d-6bcf-4ad7-9d88-d698f8c0c533" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_30378f74-5b01-4882-8c05-14dec3e9ea6b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4fbd2ecc-d66d-44ef-af6c-e7761e727d62" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_30378f74-5b01-4882-8c05-14dec3e9ea6b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTerm_c6e81511-683a-4401-895c-8bcb8d97360d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4fbd2ecc-d66d-44ef-af6c-e7761e727d62" xlink:to="loc_us-gaap_DebtInstrumentTerm_c6e81511-683a-4401-895c-8bcb8d97360d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount_c3b8c08a-d827-413f-b7e1-40c757a78e94" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LettersOfCreditOutstandingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4fbd2ecc-d66d-44ef-af6c-e7761e727d62" xlink:to="loc_us-gaap_LettersOfCreditOutstandingAmount_c3b8c08a-d827-413f-b7e1-40c757a78e94" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsNet_d296656d-8c26-4efe-98ee-53e7185ce676" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DeferredFinanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4fbd2ecc-d66d-44ef-af6c-e7761e727d62" xlink:to="loc_us-gaap_DeferredFinanceCostsNet_d296656d-8c26-4efe-98ee-53e7185ce676" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_3fffa3c9-dd06-4a52-9162-a2e48a1e9aa3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4fbd2ecc-d66d-44ef-af6c-e7761e727d62" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_3fffa3c9-dd06-4a52-9162-a2e48a1e9aa3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_d5da4879-7741-49a9-afc7-789bb9d3dec0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditFacilityCommitmentFeePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4fbd2ecc-d66d-44ef-af6c-e7761e727d62" xlink:to="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_d5da4879-7741-49a9-afc7-789bb9d3dec0" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCredit_31871d38-112e-4753-aa01-6d6d44d5bf22" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4fbd2ecc-d66d-44ef-af6c-e7761e727d62" xlink:to="loc_us-gaap_LineOfCredit_31871d38-112e-4753-aa01-6d6d44d5bf22" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_DebtInstrumentCovenantLeverageRatioMaximum_8c3a83e7-53ad-42f1-ad8c-69f83709d9ba" xlink:href="vcel-20240930.xsd#vcel_DebtInstrumentCovenantLeverageRatioMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4fbd2ecc-d66d-44ef-af6c-e7761e727d62" xlink:to="loc_vcel_DebtInstrumentCovenantLeverageRatioMaximum_8c3a83e7-53ad-42f1-ad8c-69f83709d9ba" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_DebtInstrumentCovenantIncreaseOptionLeverageRatioMaximum_e8efb078-2f72-47e6-9e03-27565b25a918" xlink:href="vcel-20240930.xsd#vcel_DebtInstrumentCovenantIncreaseOptionLeverageRatioMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_4fbd2ecc-d66d-44ef-af6c-e7761e727d62" xlink:to="loc_vcel_DebtInstrumentCovenantIncreaseOptionLeverageRatioMaximum_e8efb078-2f72-47e6-9e03-27565b25a918" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://vcel.com/role/StockBasedCompensationExpenseDetails" xlink:type="simple" xlink:href="vcel-20240930.xsd#StockBasedCompensationExpenseDetails"/>
  <link:definitionLink xlink:role="http://vcel.com/role/StockBasedCompensationExpenseDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_c34a574a-cded-43a6-8246-ad346a769f63" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_84997840-8b19-49ed-a89f-b35de1bb6546" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_c34a574a-cded-43a6-8246-ad346a769f63" xlink:to="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_84997840-8b19-49ed-a89f-b35de1bb6546" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_7ff3f5a0-ae7f-4924-a60f-96a35a51fcad" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_84997840-8b19-49ed-a89f-b35de1bb6546" xlink:to="loc_us-gaap_AwardTypeAxis_7ff3f5a0-ae7f-4924-a60f-96a35a51fcad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_7ff3f5a0-ae7f-4924-a60f-96a35a51fcad_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_7ff3f5a0-ae7f-4924-a60f-96a35a51fcad" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_7ff3f5a0-ae7f-4924-a60f-96a35a51fcad_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1c8d26ce-aa6f-4398-b4c8-16a8c7d3acaf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_7ff3f5a0-ae7f-4924-a60f-96a35a51fcad" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1c8d26ce-aa6f-4398-b4c8-16a8c7d3acaf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_EmployeeStockAndEmployeeStockOptionMember_d116f5d7-8f1d-4c68-b9bd-045f1b1db47f" xlink:href="vcel-20240930.xsd#vcel_EmployeeStockAndEmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1c8d26ce-aa6f-4398-b4c8-16a8c7d3acaf" xlink:to="loc_vcel_EmployeeStockAndEmployeeStockOptionMember_d116f5d7-8f1d-4c68-b9bd-045f1b1db47f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_65471b83-b48c-4e5f-862c-9fe0335fc4db" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_84997840-8b19-49ed-a89f-b35de1bb6546" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_65471b83-b48c-4e5f-862c-9fe0335fc4db" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_65471b83-b48c-4e5f-862c-9fe0335fc4db_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_65471b83-b48c-4e5f-862c-9fe0335fc4db" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_65471b83-b48c-4e5f-862c-9fe0335fc4db_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_357113cc-bd66-4a45-b3e1-c902c4e1e6b2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_65471b83-b48c-4e5f-862c-9fe0335fc4db" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_357113cc-bd66-4a45-b3e1-c902c4e1e6b2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfSalesMember_c2e3e68a-bd9c-4466-8656-9759daf8e6e8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CostOfSalesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_357113cc-bd66-4a45-b3e1-c902c4e1e6b2" xlink:to="loc_us-gaap_CostOfSalesMember_c2e3e68a-bd9c-4466-8656-9759daf8e6e8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpenseMember_60fe83c5-7b48-4fe6-9d95-aee1927bef20" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ResearchAndDevelopmentExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_357113cc-bd66-4a45-b3e1-c902c4e1e6b2" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpenseMember_60fe83c5-7b48-4fe6-9d95-aee1927bef20" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_97ad3d82-22fc-4e59-a830-884d85f4747b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SellingGeneralAndAdministrativeExpensesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_357113cc-bd66-4a45-b3e1-c902c4e1e6b2" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_97ad3d82-22fc-4e59-a830-884d85f4747b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_916f07d2-8f7d-4834-bbf4-031d3e9c3c32" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_c34a574a-cded-43a6-8246-ad346a769f63" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_916f07d2-8f7d-4834-bbf4-031d3e9c3c32" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://vcel.com/role/StockBasedCompensationNarrativeDetails" xlink:type="simple" xlink:href="vcel-20240930.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_dd2580b8-0726-4a89-89b5-60f2f6ea4d4a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_4800edf9-9145-458e-9f4f-20e6dba5eb7f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_dd2580b8-0726-4a89-89b5-60f2f6ea4d4a" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_4800edf9-9145-458e-9f4f-20e6dba5eb7f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_a605ebc2-a5a2-47df-8313-eb5f75c74a4a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_4800edf9-9145-458e-9f4f-20e6dba5eb7f" xlink:to="loc_us-gaap_AwardTypeAxis_a605ebc2-a5a2-47df-8313-eb5f75c74a4a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a605ebc2-a5a2-47df-8313-eb5f75c74a4a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_a605ebc2-a5a2-47df-8313-eb5f75c74a4a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a605ebc2-a5a2-47df-8313-eb5f75c74a4a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_b46e60fe-7b65-4515-bbba-5237eef5afd0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_a605ebc2-a5a2-47df-8313-eb5f75c74a4a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_b46e60fe-7b65-4515-bbba-5237eef5afd0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_758a73e9-2898-41c9-a71f-2aca70e70fd2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_b46e60fe-7b65-4515-bbba-5237eef5afd0" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_758a73e9-2898-41c9-a71f-2aca70e70fd2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_3eed7289-8bcf-4897-abbb-54a66cab157b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_dd2580b8-0726-4a89-89b5-60f2f6ea4d4a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_3eed7289-8bcf-4897-abbb-54a66cab157b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_ccc7a0f9-7b39-45a4-9b25-6adb7630703b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_dd2580b8-0726-4a89-89b5-60f2f6ea4d4a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_ccc7a0f9-7b39-45a4-9b25-6adb7630703b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_43e25e43-fbfb-4486-9e79-065534e818be" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_dd2580b8-0726-4a89-89b5-60f2f6ea4d4a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_43e25e43-fbfb-4486-9e79-065534e818be" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_135d058a-2509-48a7-a966-60fdbb5c7ce4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_dd2580b8-0726-4a89-89b5-60f2f6ea4d4a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_135d058a-2509-48a7-a966-60fdbb5c7ce4" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://vcel.com/role/NetLossPerCommonShareDetails" xlink:type="simple" xlink:href="vcel-20240930.xsd#NetLossPerCommonShareDetails"/>
  <link:definitionLink xlink:role="http://vcel.com/role/NetLossPerCommonShareDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_053a8daf-0097-426b-a96a-3a1c85d0a2ff" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_b85e0bc6-0026-402a-baa6-9da53a72598b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_053a8daf-0097-426b-a96a-3a1c85d0a2ff" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_b85e0bc6-0026-402a-baa6-9da53a72598b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_fdfa3a70-30ed-4a3a-a05f-0a840443956c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_b85e0bc6-0026-402a-baa6-9da53a72598b" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_fdfa3a70-30ed-4a3a-a05f-0a840443956c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_fdfa3a70-30ed-4a3a-a05f-0a840443956c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_fdfa3a70-30ed-4a3a-a05f-0a840443956c" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_fdfa3a70-30ed-4a3a-a05f-0a840443956c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_d9598a06-a4a5-4eed-a598-83a36bd704c8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_fdfa3a70-30ed-4a3a-a05f-0a840443956c" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_d9598a06-a4a5-4eed-a598-83a36bd704c8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_32fb04f7-76f8-413c-8964-38330fd69f79" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_d9598a06-a4a5-4eed-a598-83a36bd704c8" xlink:to="loc_us-gaap_EmployeeStockOptionMember_32fb04f7-76f8-413c-8964-38330fd69f79" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_9af9ebba-9559-40ec-989d-427f2a32a0bc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_d9598a06-a4a5-4eed-a598-83a36bd704c8" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_9af9ebba-9559-40ec-989d-427f2a32a0bc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAbstract_50e1287d-74c3-41be-8372-e0481c6f5caa" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetIncomeLossAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_053a8daf-0097-426b-a96a-3a1c85d0a2ff" xlink:to="loc_us-gaap_NetIncomeLossAbstract_50e1287d-74c3-41be-8372-e0481c6f5caa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_a49671af-9fed-4b44-95e9-6d001cbc4ba6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetIncomeLossAbstract_50e1287d-74c3-41be-8372-e0481c6f5caa" xlink:to="loc_us-gaap_NetIncomeLoss_a49671af-9fed-4b44-95e9-6d001cbc4ba6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_280aea75-802c-4a62-9cc5-e026990e2c8e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetIncomeLossAbstract_50e1287d-74c3-41be-8372-e0481c6f5caa" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_280aea75-802c-4a62-9cc5-e026990e2c8e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_1042316e-95d3-4a7e-bf48-04e0022fc940" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetIncomeLossAbstract_50e1287d-74c3-41be-8372-e0481c6f5caa" xlink:to="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_1042316e-95d3-4a7e-bf48-04e0022fc940" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_7addce03-2305-41c0-be85-09a800a9699c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetIncomeLossAbstract_50e1287d-74c3-41be-8372-e0481c6f5caa" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_7addce03-2305-41c0-be85-09a800a9699c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_78b103a8-bb00-46ef-a6b5-8f22fa7b32be" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetIncomeLossAbstract_50e1287d-74c3-41be-8372-e0481c6f5caa" xlink:to="loc_us-gaap_EarningsPerShareBasic_78b103a8-bb00-46ef-a6b5-8f22fa7b32be" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_9c889aa0-b4d7-44f9-8c1c-0798e2fbd174" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetIncomeLossAbstract_50e1287d-74c3-41be-8372-e0481c6f5caa" xlink:to="loc_us-gaap_EarningsPerShareDiluted_9c889aa0-b4d7-44f9-8c1c-0798e2fbd174" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_010b0b49-aa87-4611-9f81-039440007d60" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_053a8daf-0097-426b-a96a-3a1c85d0a2ff" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_010b0b49-aa87-4611-9f81-039440007d60" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_9d56c6ef-3f28-48e7-b629-80dea804076c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_010b0b49-aa87-4611-9f81-039440007d60" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_9d56c6ef-3f28-48e7-b629-80dea804076c" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://vcel.com/role/NexoBridLicenseandSupplyAgreementsDetails" xlink:type="simple" xlink:href="vcel-20240930.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_68c5b060-e7aa-4b54-ab33-e43493ad7fd6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RelatedPartyTransactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_c7834894-0b00-4835-98eb-bbca41e6c75d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_68c5b060-e7aa-4b54-ab33-e43493ad7fd6" xlink:to="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_c7834894-0b00-4835-98eb-bbca41e6c75d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_4a21ad68-54ea-4bd0-81d8-9e5d86b93ae5" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_c7834894-0b00-4835-98eb-bbca41e6c75d" xlink:to="loc_srt_CounterpartyNameAxis_4a21ad68-54ea-4bd0-81d8-9e5d86b93ae5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_4a21ad68-54ea-4bd0-81d8-9e5d86b93ae5_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_4a21ad68-54ea-4bd0-81d8-9e5d86b93ae5" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_4a21ad68-54ea-4bd0-81d8-9e5d86b93ae5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_066cfb1e-e472-49bc-bc95-c083bd7072ca" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_4a21ad68-54ea-4bd0-81d8-9e5d86b93ae5" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_066cfb1e-e472-49bc-bc95-c083bd7072ca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_MediWoundLtdMember_391ee1ac-e619-4be8-8f08-abb80c3ff21b" xlink:href="vcel-20240930.xsd#vcel_MediWoundLtdMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_066cfb1e-e472-49bc-bc95-c083bd7072ca" xlink:to="loc_vcel_MediWoundLtdMember_391ee1ac-e619-4be8-8f08-abb80c3ff21b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_LicenseAgreementConsideration_75654c28-4a86-4364-8853-940b758aeda7" xlink:href="vcel-20240930.xsd#vcel_LicenseAgreementConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_68c5b060-e7aa-4b54-ab33-e43493ad7fd6" xlink:to="loc_vcel_LicenseAgreementConsideration_75654c28-4a86-4364-8853-940b758aeda7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_LicenseAgreementContingentConsideration_59f82355-fe11-4240-8f41-f219748761b3" xlink:href="vcel-20240930.xsd#vcel_LicenseAgreementContingentConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_68c5b060-e7aa-4b54-ab33-e43493ad7fd6" xlink:to="loc_vcel_LicenseAgreementContingentConsideration_59f82355-fe11-4240-8f41-f219748761b3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_LicenseAgreementsMilestonePaymentsAssumedIntangibleAssets_3bb2748b-fe28-4b75-8ba3-28a46080214c" xlink:href="vcel-20240930.xsd#vcel_LicenseAgreementsMilestonePaymentsAssumedIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_68c5b060-e7aa-4b54-ab33-e43493ad7fd6" xlink:to="loc_vcel_LicenseAgreementsMilestonePaymentsAssumedIntangibleAssets_3bb2748b-fe28-4b75-8ba3-28a46080214c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireIntangibleAssets_bc4563cd-3286-4870-8a4a-3acf38a3ddfb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PaymentsToAcquireIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_68c5b060-e7aa-4b54-ab33-e43493ad7fd6" xlink:to="loc_us-gaap_PaymentsToAcquireIntangibleAssets_bc4563cd-3286-4870-8a4a-3acf38a3ddfb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_LicenseAgreementContingentConsiderationMaximum_e1d00751-9152-405f-a499-ec922247ada5" xlink:href="vcel-20240930.xsd#vcel_LicenseAgreementContingentConsiderationMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_68c5b060-e7aa-4b54-ab33-e43493ad7fd6" xlink:to="loc_vcel_LicenseAgreementContingentConsiderationMaximum_e1d00751-9152-405f-a499-ec922247ada5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_LicenseAgreementInitialMilestoneSales_d6771754-464a-46a5-9fc7-a3bf46e125c1" xlink:href="vcel-20240930.xsd#vcel_LicenseAgreementInitialMilestoneSales"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_68c5b060-e7aa-4b54-ab33-e43493ad7fd6" xlink:to="loc_vcel_LicenseAgreementInitialMilestoneSales_d6771754-464a-46a5-9fc7-a3bf46e125c1" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_LicenseAgreementSupplyAgreementTerm_5844a4cf-509e-441e-b56e-57041461aad3" xlink:href="vcel-20240930.xsd#vcel_LicenseAgreementSupplyAgreementTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_68c5b060-e7aa-4b54-ab33-e43493ad7fd6" xlink:to="loc_vcel_LicenseAgreementSupplyAgreementTerm_5844a4cf-509e-441e-b56e-57041461aad3" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_LicenseAgreementSupplyAgreementRenewalTerm_58ca9ff5-486f-4e9c-beda-31c20bb354af" xlink:href="vcel-20240930.xsd#vcel_LicenseAgreementSupplyAgreementRenewalTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_68c5b060-e7aa-4b54-ab33-e43493ad7fd6" xlink:to="loc_vcel_LicenseAgreementSupplyAgreementRenewalTerm_58ca9ff5-486f-4e9c-beda-31c20bb354af" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_LicenseAgreementSupplyAgreementOptionalAdditionalTerm_95cae0aa-f38f-4b17-aded-a610e4687e46" xlink:href="vcel-20240930.xsd#vcel_LicenseAgreementSupplyAgreementOptionalAdditionalTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_68c5b060-e7aa-4b54-ab33-e43493ad7fd6" xlink:to="loc_vcel_LicenseAgreementSupplyAgreementOptionalAdditionalTerm_95cae0aa-f38f-4b17-aded-a610e4687e46" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://xbrl.sec.gov/ecd/AwardTypeOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2024/ecd-2024.xsd#AwardTypeOnly"/>
  <link:definitionLink xlink:role="http://xbrl.sec.gov/ecd/AwardTypeOnly" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:loc xlink:type="locator" xlink:label="loc_vcel_EmployeeStockAndEmployeeStockOptionMember_4022f6ae-0552-4021-912b-1f60172f4c7a" xlink:href="vcel-20240930.xsd#vcel_EmployeeStockAndEmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_vcel_EmployeeStockAndEmployeeStockOptionMember_4022f6ae-0552-4021-912b-1f60172f4c7a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember" xlink:type="arc" order="4"/>
  </link:definitionLink>
</link:linkbase>
