

<!--XBRL Document Created with Wdesk from Workiva-->
<!-- -->
<link:linkbase xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" 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">
  <link:roleRef roleURI="http://www.vcel.com/role/BasisOfPresentation" xlink:href="astm-20190331.xsd#BasisOfPresentation" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/BasisOfPresentationDetails" xlink:href="astm-20190331.xsd#BasisOfPresentationDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/BasisOfPresentationTables" xlink:href="astm-20190331.xsd#BasisOfPresentationTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/CashEquivalentsAndInvestments" xlink:href="astm-20190331.xsd#CashEquivalentsAndInvestments" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/CashEquivalentsAndInvestmentsDetails" xlink:href="astm-20190331.xsd#CashEquivalentsAndInvestmentsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/CashEquivalentsAndInvestmentsScheduleOfFairValueOfSecuritiesDetails" xlink:href="astm-20190331.xsd#CashEquivalentsAndInvestmentsScheduleOfFairValueOfSecuritiesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/CashEquivalentsAndInvestmentsTables" xlink:href="astm-20190331.xsd#CashEquivalentsAndInvestmentsTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/CommitmentsAndContingencies" xlink:href="astm-20190331.xsd#CommitmentsAndContingencies" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/CommitmentsAndContingenciesDetails" xlink:href="astm-20190331.xsd#CommitmentsAndContingenciesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/CondensedConsolidatedBalanceSheetsUnaudited" xlink:href="astm-20190331.xsd#CondensedConsolidatedBalanceSheetsUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/CondensedConsolidatedBalanceSheetsUnauditedCalc2" xlink:href="astm-20190331.xsd#CondensedConsolidatedBalanceSheetsUnauditedCalc2" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/CondensedConsolidatedBalanceSheetsUnauditedParenthetical" xlink:href="astm-20190331.xsd#CondensedConsolidatedBalanceSheetsUnauditedParenthetical" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/CondensedConsolidatedStatementsOfCashFlowsUnaudited" xlink:href="astm-20190331.xsd#CondensedConsolidatedStatementsOfCashFlowsUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/CondensedConsolidatedStatementsOfComprehensiveLossUnaudited" xlink:href="astm-20190331.xsd#CondensedConsolidatedStatementsOfComprehensiveLossUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/CondensedConsolidatedStatementsOfOperationsUnaudited" xlink:href="astm-20190331.xsd#CondensedConsolidatedStatementsOfOperationsUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/ConsolidatedStatementsOfShareholdersEquity" xlink:href="astm-20190331.xsd#ConsolidatedStatementsOfShareholdersEquity" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/DocumentAndEntityInformation" xlink:href="astm-20190331.xsd#DocumentAndEntityInformation" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/FairValueMeasurements" xlink:href="astm-20190331.xsd#FairValueMeasurements" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/FairValueMeasurementsRecurringBasisDetails" xlink:href="astm-20190331.xsd#FairValueMeasurementsRecurringBasisDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/FairValueMeasurementsTables" xlink:href="astm-20190331.xsd#FairValueMeasurementsTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/LeasesAssetsAndLiabilitiesDetails" xlink:href="astm-20190331.xsd#LeasesAssetsAndLiabilitiesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/LeasesDetails" xlink:href="astm-20190331.xsd#LeasesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/LeasesLeaseTermAndDiscountRateDetails" xlink:href="astm-20190331.xsd#LeasesLeaseTermAndDiscountRateDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/LeasesMaturitiesOfLeaseLiabilitiesDetails" xlink:href="astm-20190331.xsd#LeasesMaturitiesOfLeaseLiabilitiesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/LeasesMaturitiesOfLeaseLiabilitiesDetailsCalc2" xlink:href="astm-20190331.xsd#LeasesMaturitiesOfLeaseLiabilitiesDetailsCalc2" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/LeasesNotes" xlink:href="astm-20190331.xsd#LeasesNotes" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/LeasesSchedulePriorToAdoptionDetails" xlink:href="astm-20190331.xsd#LeasesSchedulePriorToAdoptionDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/LeasesTables" xlink:href="astm-20190331.xsd#LeasesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/NetLossPerCommonShare" xlink:href="astm-20190331.xsd#NetLossPerCommonShare" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/NetLossPerCommonShareDetails" xlink:href="astm-20190331.xsd#NetLossPerCommonShareDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/NetLossPerCommonShareTables" xlink:href="astm-20190331.xsd#NetLossPerCommonShareTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/Organization" xlink:href="astm-20190331.xsd#Organization" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/OrganizationDetails" xlink:href="astm-20190331.xsd#OrganizationDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/RecentAccountingPronouncements" xlink:href="astm-20190331.xsd#RecentAccountingPronouncements" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/RecentAccountingPronouncementsPolicies" xlink:href="astm-20190331.xsd#RecentAccountingPronouncementsPolicies" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/Revenue" xlink:href="astm-20190331.xsd#Revenue" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/RevenueConcentrationOfCreditRiskDetails" xlink:href="astm-20190331.xsd#RevenueConcentrationOfCreditRiskDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/RevenueRevenueByProductAndCustomerDetails" xlink:href="astm-20190331.xsd#RevenueRevenueByProductAndCustomerDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/RevenueTables" xlink:href="astm-20190331.xsd#RevenueTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/SelectedBalanceSheetComponents" xlink:href="astm-20190331.xsd#SelectedBalanceSheetComponents" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/SelectedBalanceSheetComponentsAccruedExpensesDetails" xlink:href="astm-20190331.xsd#SelectedBalanceSheetComponentsAccruedExpensesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/SelectedBalanceSheetComponentsInventoryDetails" xlink:href="astm-20190331.xsd#SelectedBalanceSheetComponentsInventoryDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/SelectedBalanceSheetComponentsPropertyAndEquipmentDetails" xlink:href="astm-20190331.xsd#SelectedBalanceSheetComponentsPropertyAndEquipmentDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/SelectedBalanceSheetComponentsTables" xlink:href="astm-20190331.xsd#SelectedBalanceSheetComponentsTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/StockBasedCompensation" xlink:href="astm-20190331.xsd#StockBasedCompensation" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/StockBasedCompensationDetails" xlink:href="astm-20190331.xsd#StockBasedCompensationDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/StockBasedCompensationNonCashStockBasedCompensationExpenseDetails" xlink:href="astm-20190331.xsd#StockBasedCompensationNonCashStockBasedCompensationExpenseDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/StockBasedCompensationTables" xlink:href="astm-20190331.xsd#StockBasedCompensationTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/StockPurchaseWarrants" xlink:href="astm-20190331.xsd#StockPurchaseWarrants" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/StockPurchaseWarrantsDetails" xlink:href="astm-20190331.xsd#StockPurchaseWarrantsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/StockPurchaseWarrantsTables" xlink:href="astm-20190331.xsd#StockPurchaseWarrantsTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/SubsequentEvents" xlink:href="astm-20190331.xsd#SubsequentEvents" xlink:type="simple" />
  <link:roleRef roleURI="http://www.vcel.com/role/SubsequentEventsDetails" xlink:href="astm-20190331.xsd#SubsequentEventsDetails" xlink:type="simple" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/BasisOfPresentation" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/BasisOfPresentationDetails" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/BasisOfPresentationTables" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/CashEquivalentsAndInvestments" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/CashEquivalentsAndInvestmentsDetails" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/CashEquivalentsAndInvestmentsScheduleOfFairValueOfSecuritiesDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_f0bf2241-14f8-6ef1-e8d7-f724d52ad9c1" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_5ab305fa-195a-59cf-c0de-4b5d05fc9de4" xlink:type="locator" />
    <link:calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_f0bf2241-14f8-6ef1-e8d7-f724d52ad9c1" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_5ab305fa-195a-59cf-c0de-4b5d05fc9de4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_e0f935d0-20e2-15fc-55a1-79c116fbc07c" xlink:type="locator" />
    <link:calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_f0bf2241-14f8-6ef1-e8d7-f724d52ad9c1" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_e0f935d0-20e2-15fc-55a1-79c116fbc07c" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_5d23fa7e-7f76-6507-b72f-382f81b88e34" xlink:type="locator" />
    <link:calculationArc order="3" weight="-1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_f0bf2241-14f8-6ef1-e8d7-f724d52ad9c1" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_5d23fa7e-7f76-6507-b72f-382f81b88e34" xlink:type="arc" />
  </link:calculationLink>
  <link:calculationLink xlink:role="http://www.vcel.com/role/CashEquivalentsAndInvestmentsTables" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/CommitmentsAndContingencies" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/CommitmentsAndContingenciesDetails" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/CondensedConsolidatedBalanceSheetsUnaudited" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_Assets" xlink:label="loc_us-gaap_Assets_96dd7052-744e-d270-4e77-67944ec39152" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AssetsCurrent" xlink:label="loc_us-gaap_AssetsCurrent_d79dcc1c-93de-0ecd-2bd5-7c1f224c9b98" xlink:type="locator" />
    <link:calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_96dd7052-744e-d270-4e77-67944ec39152" xlink:to="loc_us-gaap_AssetsCurrent_d79dcc1c-93de-0ecd-2bd5-7c1f224c9b98" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccountsReceivableNetCurrent" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_928a1618-af56-709a-989c-a303706b8ca2" xlink:type="locator" />
    <link:calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_d79dcc1c-93de-0ecd-2bd5-7c1f224c9b98" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_928a1618-af56-709a-989c-a303706b8ca2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InventoryNet" xlink:label="loc_us-gaap_InventoryNet_66bcd79a-a1c3-c24d-b8b4-7a0ce373714b" xlink:type="locator" />
    <link:calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_d79dcc1c-93de-0ecd-2bd5-7c1f224c9b98" xlink:to="loc_us-gaap_InventoryNet_66bcd79a-a1c3-c24d-b8b4-7a0ce373714b" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherAssetsCurrent" xlink:label="loc_us-gaap_OtherAssetsCurrent_79aabdc0-b963-1fd1-4e81-8c0801b1ebca" xlink:type="locator" />
    <link:calculationArc order="3" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_d79dcc1c-93de-0ecd-2bd5-7c1f224c9b98" xlink:to="loc_us-gaap_OtherAssetsCurrent_79aabdc0-b963-1fd1-4e81-8c0801b1ebca" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_32f41ea9-05c6-e713-464b-586a571d1c1f" xlink:type="locator" />
    <link:calculationArc order="4" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_d79dcc1c-93de-0ecd-2bd5-7c1f224c9b98" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_32f41ea9-05c6-e713-464b-586a571d1c1f" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShortTermInvestments" xlink:label="loc_us-gaap_ShortTermInvestments_4f46bf2c-e8aa-a88a-d064-0418c3eb39b0" xlink:type="locator" />
    <link:calculationArc order="5" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_d79dcc1c-93de-0ecd-2bd5-7c1f224c9b98" xlink:to="loc_us-gaap_ShortTermInvestments_4f46bf2c-e8aa-a88a-d064-0418c3eb39b0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_f37ad080-c77a-efc5-c936-389b16abc420" xlink:type="locator" />
    <link:calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_96dd7052-744e-d270-4e77-67944ec39152" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_f37ad080-c77a-efc5-c936-389b16abc420" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeaseRightOfUseAsset" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_52f5671e-53e6-6055-795e-6bd414fd86c2" xlink:type="locator" />
    <link:calculationArc order="3" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_96dd7052-744e-d270-4e77-67944ec39152" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_52f5671e-53e6-6055-795e-6bd414fd86c2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquity" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_63817d40-f759-fa9c-45a5-8bbbb36ed5c9" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_Liabilities" xlink:label="loc_us-gaap_Liabilities_066608da-f041-4af6-3da0-95354b640e11" xlink:type="locator" />
    <link:calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_63817d40-f759-fa9c-45a5-8bbbb36ed5c9" xlink:to="loc_us-gaap_Liabilities_066608da-f041-4af6-3da0-95354b640e11" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LiabilitiesCurrent" xlink:label="loc_us-gaap_LiabilitiesCurrent_2dcbbde2-9146-a0ba-7f6c-c71b481e0841" xlink:type="locator" />
    <link:calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_066608da-f041-4af6-3da0-95354b640e11" xlink:to="loc_us-gaap_LiabilitiesCurrent_2dcbbde2-9146-a0ba-7f6c-c71b481e0841" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccountsPayableCurrent" xlink:label="loc_us-gaap_AccountsPayableCurrent_c2c48170-d0ff-2c37-effc-ff5f53e30dcb" xlink:type="locator" />
    <link:calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_2dcbbde2-9146-a0ba-7f6c-c71b481e0841" xlink:to="loc_us-gaap_AccountsPayableCurrent_c2c48170-d0ff-2c37-effc-ff5f53e30dcb" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent" xlink:label="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent_47ecca60-0dc8-25b2-6295-72031a21e0cb" xlink:type="locator" />
    <link:calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_2dcbbde2-9146-a0ba-7f6c-c71b481e0841" xlink:to="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent_47ecca60-0dc8-25b2-6295-72031a21e0cb" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeaseLiabilityCurrent" xlink:label="loc_us-gaap_OperatingLeaseLiabilityCurrent_09c9f846-159b-1776-fceb-d1cad0eb94ab" xlink:type="locator" />
    <link:calculationArc order="3" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_2dcbbde2-9146-a0ba-7f6c-c71b481e0841" xlink:to="loc_us-gaap_OperatingLeaseLiabilityCurrent_09c9f846-159b-1776-fceb-d1cad0eb94ab" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherLiabilitiesCurrent" xlink:label="loc_us-gaap_OtherLiabilitiesCurrent_4bcdb937-432e-7a7e-23c2-a441d7b89da5" xlink:type="locator" />
    <link:calculationArc order="4" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_2dcbbde2-9146-a0ba-7f6c-c71b481e0841" xlink:to="loc_us-gaap_OtherLiabilitiesCurrent_4bcdb937-432e-7a7e-23c2-a441d7b89da5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent" xlink:label="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_7e28dff2-da63-21d2-137e-ce9d56cb1b6e" xlink:type="locator" />
    <link:calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_066608da-f041-4af6-3da0-95354b640e11" xlink:to="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_7e28dff2-da63-21d2-137e-ce9d56cb1b6e" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DeferredRentCreditNoncurrent" xlink:label="loc_us-gaap_DeferredRentCreditNoncurrent_2c8b0baf-771b-c301-80d6-9e2df7367293" xlink:type="locator" />
    <link:calculationArc order="3" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_066608da-f041-4af6-3da0-95354b640e11" xlink:to="loc_us-gaap_DeferredRentCreditNoncurrent_2c8b0baf-771b-c301-80d6-9e2df7367293" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockholdersEquity" xlink:label="loc_us-gaap_StockholdersEquity_6765f135-8c69-bebc-a116-d59a52a5b2f2" xlink:type="locator" />
    <link:calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_63817d40-f759-fa9c-45a5-8bbbb36ed5c9" xlink:to="loc_us-gaap_StockholdersEquity_6765f135-8c69-bebc-a116-d59a52a5b2f2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommonStockValue" xlink:label="loc_us-gaap_CommonStockValue_aefe3f0c-abe4-5b83-9a64-da77d8e253dd" xlink:type="locator" />
    <link:calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_6765f135-8c69-bebc-a116-d59a52a5b2f2" xlink:to="loc_us-gaap_CommonStockValue_aefe3f0c-abe4-5b83-9a64-da77d8e253dd" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_WarrantsAndRightsOutstanding" xlink:label="loc_us-gaap_WarrantsAndRightsOutstanding_e955c293-6e20-6623-80a7-235affaf2074" xlink:type="locator" />
    <link:calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_6765f135-8c69-bebc-a116-d59a52a5b2f2" xlink:to="loc_us-gaap_WarrantsAndRightsOutstanding_e955c293-6e20-6623-80a7-235affaf2074" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_a59bc5ae-63a0-c9bc-32f7-e2bd9f32bd26" xlink:type="locator" />
    <link:calculationArc order="3" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_6765f135-8c69-bebc-a116-d59a52a5b2f2" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_a59bc5ae-63a0-c9bc-32f7-e2bd9f32bd26" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_798442bf-12e1-d944-3fa1-8b797b67482e" xlink:type="locator" />
    <link:calculationArc order="4" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_6765f135-8c69-bebc-a116-d59a52a5b2f2" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_798442bf-12e1-d944-3fa1-8b797b67482e" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CommitmentsAndContingencies" xlink:label="loc_us-gaap_CommitmentsAndContingencies_f0c68f4f-7ec1-d447-8ba7-0f2766abbe67" xlink:type="locator" />
    <link:calculationArc order="3" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_63817d40-f759-fa9c-45a5-8bbbb36ed5c9" xlink:to="loc_us-gaap_CommitmentsAndContingencies_f0c68f4f-7ec1-d447-8ba7-0f2766abbe67" xlink:type="arc" />
  </link:calculationLink>
  <link:calculationLink xlink:role="http://www.vcel.com/role/CondensedConsolidatedBalanceSheetsUnauditedCalc2" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/CondensedConsolidatedBalanceSheetsUnauditedParenthetical" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/CondensedConsolidatedStatementsOfCashFlowsUnaudited" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease" xlink:label="loc_us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease_ad8f5587-cd30-97dd-9cf0-81ed4f58516c" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_1bd0bd4e-4a6f-b052-029c-0ecb0c520251" xlink:type="locator" />
    <link:calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease_ad8f5587-cd30-97dd-9cf0-81ed4f58516c" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_1bd0bd4e-4a6f-b052-029c-0ecb0c520251" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_a10eea14-f4db-3125-d183-77bb54500e95" xlink:type="locator" />
    <link:calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_1bd0bd4e-4a6f-b052-029c-0ecb0c520251" xlink:to="loc_us-gaap_NetIncomeLoss_a10eea14-f4db-3125-d183-77bb54500e95" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DepreciationDepletionAndAmortization" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_b11c1cb0-596b-4c3d-0283-76cef67837c7" xlink:type="locator" />
    <link:calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_1bd0bd4e-4a6f-b052-029c-0ecb0c520251" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_b11c1cb0-596b-4c3d-0283-76cef67837c7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ShareBasedCompensation" xlink:label="loc_us-gaap_ShareBasedCompensation_90cbc3ab-f555-6407-b3b4-b2bfa84c9f18" xlink:type="locator" />
    <link:calculationArc order="3" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_1bd0bd4e-4a6f-b052-029c-0ecb0c520251" xlink:to="loc_us-gaap_ShareBasedCompensation_90cbc3ab-f555-6407-b3b4-b2bfa84c9f18" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueAdjustmentOfWarrants" xlink:label="loc_us-gaap_FairValueAdjustmentOfWarrants_2d563f7c-9c66-4ccb-995c-599c680a5434" xlink:type="locator" />
    <link:calculationArc order="4" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_1bd0bd4e-4a6f-b052-029c-0ecb0c520251" xlink:to="loc_us-gaap_FairValueAdjustmentOfWarrants_2d563f7c-9c66-4ccb-995c-599c680a5434" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GainLossOnDispositionOfAssets1" xlink:label="loc_us-gaap_GainLossOnDispositionOfAssets1_d98f2ddb-80a6-3621-3b7b-a9eb2bffa58f" xlink:type="locator" />
    <link:calculationArc order="5" weight="-1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_1bd0bd4e-4a6f-b052-029c-0ecb0c520251" xlink:to="loc_us-gaap_GainLossOnDispositionOfAssets1_d98f2ddb-80a6-3621-3b7b-a9eb2bffa58f" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ForeignCurrencyTransactionGainLossBeforeTax" xlink:label="loc_us-gaap_ForeignCurrencyTransactionGainLossBeforeTax_743ecb1a-adc1-2b63-ff24-350f33c715bd" xlink:type="locator" />
    <link:calculationArc order="6" weight="-1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_1bd0bd4e-4a6f-b052-029c-0ecb0c520251" xlink:to="loc_us-gaap_ForeignCurrencyTransactionGainLossBeforeTax_743ecb1a-adc1-2b63-ff24-350f33c715bd" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccretionAmortizationOfDiscountsAndPremiumsInvestments" xlink:label="loc_us-gaap_AccretionAmortizationOfDiscountsAndPremiumsInvestments_4f3832d5-e2fd-470b-5e04-ece38e7ab02d" xlink:type="locator" />
    <link:calculationArc order="7" weight="-1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_1bd0bd4e-4a6f-b052-029c-0ecb0c520251" xlink:to="loc_us-gaap_AccretionAmortizationOfDiscountsAndPremiumsInvestments_4f3832d5-e2fd-470b-5e04-ece38e7ab02d" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinanceLeaseRightOfUseAssetAmortization" xlink:label="loc_us-gaap_FinanceLeaseRightOfUseAssetAmortization_0c835b1b-073b-1726-45ed-7f72b8f658d6" xlink:type="locator" />
    <link:calculationArc order="8" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_1bd0bd4e-4a6f-b052-029c-0ecb0c520251" xlink:to="loc_us-gaap_FinanceLeaseRightOfUseAssetAmortization_0c835b1b-073b-1726-45ed-7f72b8f658d6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncreaseDecreaseInInventories" xlink:label="loc_us-gaap_IncreaseDecreaseInInventories_334f1d33-7cae-7fd2-9d83-bb387fc2f3dd" xlink:type="locator" />
    <link:calculationArc order="9" weight="-1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_1bd0bd4e-4a6f-b052-029c-0ecb0c520251" xlink:to="loc_us-gaap_IncreaseDecreaseInInventories_334f1d33-7cae-7fd2-9d83-bb387fc2f3dd" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncreaseDecreaseInReceivables" xlink:label="loc_us-gaap_IncreaseDecreaseInReceivables_7357074f-3c04-6e15-2de1-4b57df4c66ed" xlink:type="locator" />
    <link:calculationArc order="10" weight="-1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_1bd0bd4e-4a6f-b052-029c-0ecb0c520251" xlink:to="loc_us-gaap_IncreaseDecreaseInReceivables_7357074f-3c04-6e15-2de1-4b57df4c66ed" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncreaseDecreaseInOtherCurrentAssets" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherCurrentAssets_30b51b02-ce1a-7a8d-83e5-0db42b6e72ce" xlink:type="locator" />
    <link:calculationArc order="11" weight="-1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_1bd0bd4e-4a6f-b052-029c-0ecb0c520251" xlink:to="loc_us-gaap_IncreaseDecreaseInOtherCurrentAssets_30b51b02-ce1a-7a8d-83e5-0db42b6e72ce" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities_91c354d1-d18f-051e-80cb-f13c01058b9d" xlink:type="locator" />
    <link:calculationArc order="12" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_1bd0bd4e-4a6f-b052-029c-0ecb0c520251" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities_91c354d1-d18f-051e-80cb-f13c01058b9d" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncreaseDecreaseInEmployeeRelatedLiabilities" xlink:label="loc_us-gaap_IncreaseDecreaseInEmployeeRelatedLiabilities_bb8c0c41-60b6-6ad9-c835-6a671aae07c5" xlink:type="locator" />
    <link:calculationArc order="13" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_1bd0bd4e-4a6f-b052-029c-0ecb0c520251" xlink:to="loc_us-gaap_IncreaseDecreaseInEmployeeRelatedLiabilities_bb8c0c41-60b6-6ad9-c835-6a671aae07c5" xlink:type="arc" />
    <link:loc xlink:href="astm-20190331.xsd#astm_IncreaseDecreaseInLeaseLiabilities" xlink:label="loc_astm_IncreaseDecreaseInLeaseLiabilities_BF9962727310EB7B2EF579545B2CA171" xlink:type="locator" />
    <link:calculationArc order="14" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_1bd0bd4e-4a6f-b052-029c-0ecb0c520251" xlink:to="loc_astm_IncreaseDecreaseInLeaseLiabilities_BF9962727310EB7B2EF579545B2CA171" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncreaseDecreaseInOtherOperatingCapitalNet" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherOperatingCapitalNet_a9646808-098c-8496-e17a-df690055019e" xlink:type="locator" />
    <link:calculationArc order="15" weight="-1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_1bd0bd4e-4a6f-b052-029c-0ecb0c520251" xlink:to="loc_us-gaap_IncreaseDecreaseInOtherOperatingCapitalNet_a9646808-098c-8496-e17a-df690055019e" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_28655e34-499f-b7bf-c54f-5de0990d0c65" xlink:type="locator" />
    <link:calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease_ad8f5587-cd30-97dd-9cf0-81ed4f58516c" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_28655e34-499f-b7bf-c54f-5de0990d0c65" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_80abba07-181c-6ed2-349d-9d7dfc078eab" xlink:type="locator" />
    <link:calculationArc order="1" weight="-1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_28655e34-499f-b7bf-c54f-5de0990d0c65" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_80abba07-181c-6ed2-349d-9d7dfc078eab" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ProceedsFromSaleMaturityAndCollectionOfShorttermInvestments" xlink:label="loc_us-gaap_ProceedsFromSaleMaturityAndCollectionOfShorttermInvestments_5c32e089-1c68-9250-3aa4-e30cde5c6fb3" xlink:type="locator" />
    <link:calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_28655e34-499f-b7bf-c54f-5de0990d0c65" xlink:to="loc_us-gaap_ProceedsFromSaleMaturityAndCollectionOfShorttermInvestments_5c32e089-1c68-9250-3aa4-e30cde5c6fb3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:label="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_6d89f221-3ede-36b2-fcad-4a4ce1606f6a" xlink:type="locator" />
    <link:calculationArc order="3" weight="-1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_28655e34-499f-b7bf-c54f-5de0990d0c65" xlink:to="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_6d89f221-3ede-36b2-fcad-4a4ce1606f6a" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_d8917e24-06dd-060d-a290-e426c7895e54" xlink:type="locator" />
    <link:calculationArc order="3" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease_ad8f5587-cd30-97dd-9cf0-81ed4f58516c" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_d8917e24-06dd-060d-a290-e426c7895e54" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ProceedsFromStockOptionsExercised" xlink:label="loc_us-gaap_ProceedsFromStockOptionsExercised_706d3cc5-3df5-1e1a-5067-c02728407eb6" xlink:type="locator" />
    <link:calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_d8917e24-06dd-060d-a290-e426c7895e54" xlink:to="loc_us-gaap_ProceedsFromStockOptionsExercised_706d3cc5-3df5-1e1a-5067-c02728407eb6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ProceedsFromWarrantExercises" xlink:label="loc_us-gaap_ProceedsFromWarrantExercises_29fc0ccf-d68e-39c1-8f4d-25c014f2bb16" xlink:type="locator" />
    <link:calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_d8917e24-06dd-060d-a290-e426c7895e54" xlink:to="loc_us-gaap_ProceedsFromWarrantExercises_29fc0ccf-d68e-39c1-8f4d-25c014f2bb16" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ProceedsFromPaymentsForOtherFinancingActivities" xlink:label="loc_us-gaap_ProceedsFromPaymentsForOtherFinancingActivities_38e7f3e2-9d1a-8772-e4aa-fb2cb7d8adc0" xlink:type="locator" />
    <link:calculationArc order="3" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_d8917e24-06dd-060d-a290-e426c7895e54" xlink:to="loc_us-gaap_ProceedsFromPaymentsForOtherFinancingActivities_38e7f3e2-9d1a-8772-e4aa-fb2cb7d8adc0" xlink:type="arc" />
  </link:calculationLink>
  <link:calculationLink xlink:role="http://www.vcel.com/role/CondensedConsolidatedStatementsOfComprehensiveLossUnaudited" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ComprehensiveIncomeNetOfTax" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTax_cf605d39-9067-2f07-a6b5-7dfa6481009e" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent" xlink:label="loc_us-gaap_OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent_c7333cca-378d-a6fc-ae13-b512babfcdeb" xlink:type="locator" />
    <link:calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTax_cf605d39-9067-2f07-a6b5-7dfa6481009e" xlink:to="loc_us-gaap_OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent_c7333cca-378d-a6fc-ae13-b512babfcdeb" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_a10eea14-f4db-3125-d183-77bb54500e95" xlink:type="locator" />
    <link:calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTax_cf605d39-9067-2f07-a6b5-7dfa6481009e" xlink:to="loc_us-gaap_NetIncomeLoss_a10eea14-f4db-3125-d183-77bb54500e95" xlink:type="arc" />
  </link:calculationLink>
  <link:calculationLink xlink:role="http://www.vcel.com/role/CondensedConsolidatedStatementsOfOperationsUnaudited" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_a10eea14-f4db-3125-d183-77bb54500e95" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="loc_us-gaap_OperatingIncomeLoss_5c890570-5904-7978-36d8-35b96dcf45ab" xlink:type="locator" />
    <link:calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_a10eea14-f4db-3125-d183-77bb54500e95" xlink:to="loc_us-gaap_OperatingIncomeLoss_5c890570-5904-7978-36d8-35b96dcf45ab" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_GrossProfit" xlink:label="loc_us-gaap_GrossProfit_df00e688-c7aa-f044-9cba-c48e7c14e35b" xlink:type="locator" />
    <link:calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingIncomeLoss_5c890570-5904-7978-36d8-35b96dcf45ab" xlink:to="loc_us-gaap_GrossProfit_df00e688-c7aa-f044-9cba-c48e7c14e35b" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_1c604cfe-da19-5194-72b6-98be0130cfb7" xlink:type="locator" />
    <link:calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_GrossProfit_df00e688-c7aa-f044-9cba-c48e7c14e35b" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_1c604cfe-da19-5194-72b6-98be0130cfb7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CostOfGoodsAndServicesSold" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSold_1c65a201-fd8e-32d7-dad9-c6d1d5719594" xlink:type="locator" />
    <link:calculationArc order="2" weight="-1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_GrossProfit_df00e688-c7aa-f044-9cba-c48e7c14e35b" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSold_1c65a201-fd8e-32d7-dad9-c6d1d5719594" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingExpenses" xlink:label="loc_us-gaap_OperatingExpenses_a2f4cf19-54a3-c9c5-9b4d-23b76125e270" xlink:type="locator" />
    <link:calculationArc order="2" weight="-1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingIncomeLoss_5c890570-5904-7978-36d8-35b96dcf45ab" xlink:to="loc_us-gaap_OperatingExpenses_a2f4cf19-54a3-c9c5-9b4d-23b76125e270" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ResearchAndDevelopmentExpense" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense_11c9d7e5-c56e-e78a-ae7b-17989a817204" xlink:type="locator" />
    <link:calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingExpenses_a2f4cf19-54a3-c9c5-9b4d-23b76125e270" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense_11c9d7e5-c56e-e78a-ae7b-17989a817204" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SellingGeneralAndAdministrativeExpense" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpense_693c47dd-e6fa-9c85-6a65-7baa26f76b5e" xlink:type="locator" />
    <link:calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingExpenses_a2f4cf19-54a3-c9c5-9b4d-23b76125e270" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpense_693c47dd-e6fa-9c85-6a65-7baa26f76b5e" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NonoperatingIncomeExpense" xlink:label="loc_us-gaap_NonoperatingIncomeExpense_c5398800-6e68-ed86-a47c-16106e0730c2" xlink:type="locator" />
    <link:calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_a10eea14-f4db-3125-d183-77bb54500e95" xlink:to="loc_us-gaap_NonoperatingIncomeExpense_c5398800-6e68-ed86-a47c-16106e0730c2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FairValueAdjustmentOfWarrants" xlink:label="loc_us-gaap_FairValueAdjustmentOfWarrants_2d563f7c-9c66-4ccb-995c-599c680a5434" xlink:type="locator" />
    <link:calculationArc order="1" weight="-1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NonoperatingIncomeExpense_c5398800-6e68-ed86-a47c-16106e0730c2" xlink:to="loc_us-gaap_FairValueAdjustmentOfWarrants_2d563f7c-9c66-4ccb-995c-599c680a5434" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InvestmentIncomeInterest" xlink:label="loc_us-gaap_InvestmentIncomeInterest_5fcda05e-5b0d-7f20-111d-115dec47eebc" xlink:type="locator" />
    <link:calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NonoperatingIncomeExpense_c5398800-6e68-ed86-a47c-16106e0730c2" xlink:to="loc_us-gaap_InvestmentIncomeInterest_5fcda05e-5b0d-7f20-111d-115dec47eebc" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InterestExpense" xlink:label="loc_us-gaap_InterestExpense_a56b34b7-57ab-a07c-7f03-8366849a14f0" xlink:type="locator" />
    <link:calculationArc order="3" weight="-1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NonoperatingIncomeExpense_c5398800-6e68-ed86-a47c-16106e0730c2" xlink:to="loc_us-gaap_InterestExpense_a56b34b7-57ab-a07c-7f03-8366849a14f0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherNonoperatingIncomeExpense" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_41e96f8d-e499-8de8-69a8-27f1c7d4df6e" xlink:type="locator" />
    <link:calculationArc order="4" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NonoperatingIncomeExpense_c5398800-6e68-ed86-a47c-16106e0730c2" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_41e96f8d-e499-8de8-69a8-27f1c7d4df6e" xlink:type="arc" />
  </link:calculationLink>
  <link:calculationLink xlink:role="http://www.vcel.com/role/ConsolidatedStatementsOfShareholdersEquity" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/DocumentAndEntityInformation" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/FairValueMeasurements" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/FairValueMeasurementsRecurringBasisDetails" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/FairValueMeasurementsTables" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/LeasesAssetsAndLiabilitiesDetails" xlink:type="extended">
    <link:loc xlink:href="astm-20190331.xsd#astm_LeaseLiabilityCurrent" xlink:label="loc_astm_LeaseLiabilityCurrent_61DC5E96CAAAF1882F2F792D38E11659" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeaseLiabilityCurrent" xlink:label="loc_us-gaap_OperatingLeaseLiabilityCurrent_09c9f846-159b-1776-fceb-d1cad0eb94ab" xlink:type="locator" />
    <link:calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_astm_LeaseLiabilityCurrent_61DC5E96CAAAF1882F2F792D38E11659" xlink:to="loc_us-gaap_OperatingLeaseLiabilityCurrent_09c9f846-159b-1776-fceb-d1cad0eb94ab" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinanceLeaseLiabilityCurrent" xlink:label="loc_us-gaap_FinanceLeaseLiabilityCurrent_1396153e-4fa1-90ea-08ee-fec369a9d7aa" xlink:type="locator" />
    <link:calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_astm_LeaseLiabilityCurrent_61DC5E96CAAAF1882F2F792D38E11659" xlink:to="loc_us-gaap_FinanceLeaseLiabilityCurrent_1396153e-4fa1-90ea-08ee-fec369a9d7aa" xlink:type="arc" />
    <link:loc xlink:href="astm-20190331.xsd#astm_RightOfUseAsset" xlink:label="loc_astm_RightOfUseAsset_E11535AB7828B95AC55179258BE7A0B9" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeaseRightOfUseAsset" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_52f5671e-53e6-6055-795e-6bd414fd86c2" xlink:type="locator" />
    <link:calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_astm_RightOfUseAsset_E11535AB7828B95AC55179258BE7A0B9" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_52f5671e-53e6-6055-795e-6bd414fd86c2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinanceLeaseRightOfUseAsset" xlink:label="loc_us-gaap_FinanceLeaseRightOfUseAsset_b54d8caa-f4e6-5da2-d7a5-67f9fcda4cc5" xlink:type="locator" />
    <link:calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_astm_RightOfUseAsset_E11535AB7828B95AC55179258BE7A0B9" xlink:to="loc_us-gaap_FinanceLeaseRightOfUseAsset_b54d8caa-f4e6-5da2-d7a5-67f9fcda4cc5" xlink:type="arc" />
    <link:loc xlink:href="astm-20190331.xsd#astm_LeaseLiabilityNoncurrent" xlink:label="loc_astm_LeaseLiabilityNoncurrent_9A11C8AD388DC1A42BED792E127863E7" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent" xlink:label="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_7e28dff2-da63-21d2-137e-ce9d56cb1b6e" xlink:type="locator" />
    <link:calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_astm_LeaseLiabilityNoncurrent_9A11C8AD388DC1A42BED792E127863E7" xlink:to="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_7e28dff2-da63-21d2-137e-ce9d56cb1b6e" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinanceLeaseLiabilityNoncurrent" xlink:label="loc_us-gaap_FinanceLeaseLiabilityNoncurrent_a2966f09-089c-308f-404f-2425a9943c5c" xlink:type="locator" />
    <link:calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_astm_LeaseLiabilityNoncurrent_9A11C8AD388DC1A42BED792E127863E7" xlink:to="loc_us-gaap_FinanceLeaseLiabilityNoncurrent_a2966f09-089c-308f-404f-2425a9943c5c" xlink:type="arc" />
  </link:calculationLink>
  <link:calculationLink xlink:role="http://www.vcel.com/role/LeasesDetails" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/LeasesLeaseTermAndDiscountRateDetails" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/LeasesMaturitiesOfLeaseLiabilitiesDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_4d26bd18-43c4-5981-04d4-83d0e9328a1d" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear_d0e3c4ab-df94-52c6-3761-ce2ed0f2f507" xlink:type="locator" />
    <link:calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_4d26bd18-43c4-5981-04d4-83d0e9328a1d" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear_d0e3c4ab-df94-52c6-3761-ce2ed0f2f507" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_e0f20176-305e-e29f-ab09-584aea596901" xlink:type="locator" />
    <link:calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_4d26bd18-43c4-5981-04d4-83d0e9328a1d" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_e0f20176-305e-e29f-ab09-584aea596901" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_8e35e675-3955-0e95-1b9c-d08dd410962e" xlink:type="locator" />
    <link:calculationArc order="3" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_4d26bd18-43c4-5981-04d4-83d0e9328a1d" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_8e35e675-3955-0e95-1b9c-d08dd410962e" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_852d78fc-d4b9-e5fb-fd5a-9da7d3d49669" xlink:type="locator" />
    <link:calculationArc order="4" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_4d26bd18-43c4-5981-04d4-83d0e9328a1d" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_852d78fc-d4b9-e5fb-fd5a-9da7d3d49669" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive_7a6864a2-d55e-24e7-17f1-75d5cad038ee" xlink:type="locator" />
    <link:calculationArc order="5" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_4d26bd18-43c4-5981-04d4-83d0e9328a1d" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive_7a6864a2-d55e-24e7-17f1-75d5cad038ee" xlink:type="arc" />
    <link:loc xlink:href="astm-20190331.xsd#astm_LesseeOperatingLeaseLiabilityPaymentsDueYearSix" xlink:label="loc_astm_LesseeOperatingLeaseLiabilityPaymentsDueYearSix_87C28B23B9F3CC0AA74A45FACB5828F0" xlink:type="locator" />
    <link:calculationArc order="6" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_4d26bd18-43c4-5981-04d4-83d0e9328a1d" xlink:to="loc_astm_LesseeOperatingLeaseLiabilityPaymentsDueYearSix_87C28B23B9F3CC0AA74A45FACB5828F0" xlink:type="arc" />
    <link:loc xlink:href="astm-20190331.xsd#astm_LesseeOperatingLeaseLiabilityPaymentsDueafterYearSix" xlink:label="loc_astm_LesseeOperatingLeaseLiabilityPaymentsDueafterYearSix_D733878DE59BDAE8446C45FBF9AF5DB7" xlink:type="locator" />
    <link:calculationArc order="7" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_4d26bd18-43c4-5981-04d4-83d0e9328a1d" xlink:to="loc_astm_LesseeOperatingLeaseLiabilityPaymentsDueafterYearSix_D733878DE59BDAE8446C45FBF9AF5DB7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDue" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_10e0bd29-5982-7ebb-bb17-5361bca728ac" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsRemainderOfFiscalYear" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsRemainderOfFiscalYear_38a6b090-3be5-7f8a-d16b-973e8b111ee5" xlink:type="locator" />
    <link:calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_10e0bd29-5982-7ebb-bb17-5361bca728ac" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsRemainderOfFiscalYear_38a6b090-3be5-7f8a-d16b-973e8b111ee5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo_9a13a07a-4477-75df-f259-93d353e0436e" xlink:type="locator" />
    <link:calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_10e0bd29-5982-7ebb-bb17-5361bca728ac" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo_9a13a07a-4477-75df-f259-93d353e0436e" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree_9b0526b4-fafb-8f2d-7747-7f90a19a677b" xlink:type="locator" />
    <link:calculationArc order="3" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_10e0bd29-5982-7ebb-bb17-5361bca728ac" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree_9b0526b4-fafb-8f2d-7747-7f90a19a677b" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour_0b9b28ab-56f0-4494-24e3-113280a3b1c8" xlink:type="locator" />
    <link:calculationArc order="4" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_10e0bd29-5982-7ebb-bb17-5361bca728ac" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour_0b9b28ab-56f0-4494-24e3-113280a3b1c8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive_7c9dbff4-7abb-6fd4-3703-b36ff0ec4db1" xlink:type="locator" />
    <link:calculationArc order="5" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_10e0bd29-5982-7ebb-bb17-5361bca728ac" xlink:to="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive_7c9dbff4-7abb-6fd4-3703-b36ff0ec4db1" xlink:type="arc" />
    <link:loc xlink:href="astm-20190331.xsd#astm_FinanceLeaseLiabilityPaymentsDueYearSix" xlink:label="loc_astm_FinanceLeaseLiabilityPaymentsDueYearSix_D1A2F9874FB7DB759B6045FFEE00C864" xlink:type="locator" />
    <link:calculationArc order="6" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_10e0bd29-5982-7ebb-bb17-5361bca728ac" xlink:to="loc_astm_FinanceLeaseLiabilityPaymentsDueYearSix_D1A2F9874FB7DB759B6045FFEE00C864" xlink:type="arc" />
    <link:loc xlink:href="astm-20190331.xsd#astm_FinanceLeaseLiabilityPaymentsDueafterYearSix" xlink:label="loc_astm_FinanceLeaseLiabilityPaymentsDueafterYearSix_7B6AD983B55A528A212A4601986EF06D" xlink:type="locator" />
    <link:calculationArc order="7" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_10e0bd29-5982-7ebb-bb17-5361bca728ac" xlink:to="loc_astm_FinanceLeaseLiabilityPaymentsDueafterYearSix_7B6AD983B55A528A212A4601986EF06D" xlink:type="arc" />
    <link:loc xlink:href="astm-20190331.xsd#astm_LeaseLiabilityPaymentsDue" xlink:label="loc_astm_LeaseLiabilityPaymentsDue_5B5F2379C887F3463B687943604B98DD" xlink:type="locator" />
    <link:loc xlink:href="astm-20190331.xsd#astm_LeaseLiabilityPaymentsDueRemainderOfFiscalYear" xlink:label="loc_astm_LeaseLiabilityPaymentsDueRemainderOfFiscalYear_C7D7BA03188E9F1FC21A794048397DC7" xlink:type="locator" />
    <link:calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_astm_LeaseLiabilityPaymentsDue_5B5F2379C887F3463B687943604B98DD" xlink:to="loc_astm_LeaseLiabilityPaymentsDueRemainderOfFiscalYear_C7D7BA03188E9F1FC21A794048397DC7" xlink:type="arc" />
    <link:loc xlink:href="astm-20190331.xsd#astm_LeaseLiabilityPaymentsDueYearTwo" xlink:label="loc_astm_LeaseLiabilityPaymentsDueYearTwo_CADF2DB210AFF2B643007940A801204F" xlink:type="locator" />
    <link:calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_astm_LeaseLiabilityPaymentsDue_5B5F2379C887F3463B687943604B98DD" xlink:to="loc_astm_LeaseLiabilityPaymentsDueYearTwo_CADF2DB210AFF2B643007940A801204F" xlink:type="arc" />
    <link:loc xlink:href="astm-20190331.xsd#astm_LeaseLiabilityPaymentsDueYearThree" xlink:label="loc_astm_LeaseLiabilityPaymentsDueYearThree_A7C0F519C2AAB245802A79415C06F4C8" xlink:type="locator" />
    <link:calculationArc order="3" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_astm_LeaseLiabilityPaymentsDue_5B5F2379C887F3463B687943604B98DD" xlink:to="loc_astm_LeaseLiabilityPaymentsDueYearThree_A7C0F519C2AAB245802A79415C06F4C8" xlink:type="arc" />
    <link:loc xlink:href="astm-20190331.xsd#astm_LeaseLiabilityPaymentsDueYearFour" xlink:label="loc_astm_LeaseLiabilityPaymentsDueYearFour_CDAD158A338BA24AFA5A7941A45DA6E0" xlink:type="locator" />
    <link:calculationArc order="4" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_astm_LeaseLiabilityPaymentsDue_5B5F2379C887F3463B687943604B98DD" xlink:to="loc_astm_LeaseLiabilityPaymentsDueYearFour_CDAD158A338BA24AFA5A7941A45DA6E0" xlink:type="arc" />
    <link:loc xlink:href="astm-20190331.xsd#astm_LeaseLiabilityPaymentsDueYearFive" xlink:label="loc_astm_LeaseLiabilityPaymentsDueYearFive_33E757251D65D17B468979421476DFB8" xlink:type="locator" />
    <link:calculationArc order="5" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_astm_LeaseLiabilityPaymentsDue_5B5F2379C887F3463B687943604B98DD" xlink:to="loc_astm_LeaseLiabilityPaymentsDueYearFive_33E757251D65D17B468979421476DFB8" xlink:type="arc" />
    <link:loc xlink:href="astm-20190331.xsd#astm_LeaseLiabilityPaymentsDueYearSix" xlink:label="loc_astm_LeaseLiabilityPaymentsDueYearSix_2B021B0D4781969AAFF5794264582F85" xlink:type="locator" />
    <link:calculationArc order="6" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_astm_LeaseLiabilityPaymentsDue_5B5F2379C887F3463B687943604B98DD" xlink:to="loc_astm_LeaseLiabilityPaymentsDueYearSix_2B021B0D4781969AAFF5794264582F85" xlink:type="arc" />
    <link:loc xlink:href="astm-20190331.xsd#astm_LeaseLiabilityPaymentsDueAfterYearSix" xlink:label="loc_astm_LeaseLiabilityPaymentsDueAfterYearSix_170E804FCE2A577B191A7942C9E888D4" xlink:type="locator" />
    <link:calculationArc order="7" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_astm_LeaseLiabilityPaymentsDue_5B5F2379C887F3463B687943604B98DD" xlink:to="loc_astm_LeaseLiabilityPaymentsDueAfterYearSix_170E804FCE2A577B191A7942C9E888D4" xlink:type="arc" />
  </link:calculationLink>
  <link:calculationLink xlink:role="http://www.vcel.com/role/LeasesMaturitiesOfLeaseLiabilitiesDetailsCalc2" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_C7E12229A0B5D8FD93C78F4F0E59BB41_4d26bd18-43c4-5981-04d4-83d0e9328a1d" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_C7E12229A0B5D8FD93C78F4F0E59BB41_dba432e7-eec4-e0dc-718d-f46fe263fe47" xlink:type="locator" />
    <link:calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_C7E12229A0B5D8FD93C78F4F0E59BB41_4d26bd18-43c4-5981-04d4-83d0e9328a1d" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_C7E12229A0B5D8FD93C78F4F0E59BB41_dba432e7-eec4-e0dc-718d-f46fe263fe47" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeaseLiability" xlink:label="loc_us-gaap_OperatingLeaseLiability_C7E12229A0B5D8FD93C78F4F0E59BB41_41784c6f-4555-af92-3354-8f8701c77f60" xlink:type="locator" />
    <link:calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_C7E12229A0B5D8FD93C78F4F0E59BB41_4d26bd18-43c4-5981-04d4-83d0e9328a1d" xlink:to="loc_us-gaap_OperatingLeaseLiability_C7E12229A0B5D8FD93C78F4F0E59BB41_41784c6f-4555-af92-3354-8f8701c77f60" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDue" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_C7E12229A0B5D8FD93C78F4F0E59BB41_10e0bd29-5982-7ebb-bb17-5361bca728ac" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount" xlink:label="loc_us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount_C7E12229A0B5D8FD93C78F4F0E59BB41_ad6eb3ad-e10c-27fa-bfaf-ecbc91c6e0bd" xlink:type="locator" />
    <link:calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_C7E12229A0B5D8FD93C78F4F0E59BB41_10e0bd29-5982-7ebb-bb17-5361bca728ac" xlink:to="loc_us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount_C7E12229A0B5D8FD93C78F4F0E59BB41_ad6eb3ad-e10c-27fa-bfaf-ecbc91c6e0bd" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinanceLeaseLiability" xlink:label="loc_us-gaap_FinanceLeaseLiability_C7E12229A0B5D8FD93C78F4F0E59BB41_f8462fb4-d805-7572-eefc-3247d0b39ea6" xlink:type="locator" />
    <link:calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_C7E12229A0B5D8FD93C78F4F0E59BB41_10e0bd29-5982-7ebb-bb17-5361bca728ac" xlink:to="loc_us-gaap_FinanceLeaseLiability_C7E12229A0B5D8FD93C78F4F0E59BB41_f8462fb4-d805-7572-eefc-3247d0b39ea6" xlink:type="arc" />
    <link:loc xlink:href="astm-20190331.xsd#astm_LeaseLiabilityPaymentsDue" xlink:label="loc_astm_LeaseLiabilityPaymentsDue_C7E12229A0B5D8FD93C78F4F0E59BB41_5B5F2379C887F3463B687943604B98DD" xlink:type="locator" />
    <link:loc xlink:href="astm-20190331.xsd#astm_LeaseLiabilityUndiscountedExcessAmount" xlink:label="loc_astm_LeaseLiabilityUndiscountedExcessAmount_C7E12229A0B5D8FD93C78F4F0E59BB41_C79C9F7F02179AE7EBED7943FACD34CA" xlink:type="locator" />
    <link:calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_astm_LeaseLiabilityPaymentsDue_C7E12229A0B5D8FD93C78F4F0E59BB41_5B5F2379C887F3463B687943604B98DD" xlink:to="loc_astm_LeaseLiabilityUndiscountedExcessAmount_C7E12229A0B5D8FD93C78F4F0E59BB41_C79C9F7F02179AE7EBED7943FACD34CA" xlink:type="arc" />
    <link:loc xlink:href="astm-20190331.xsd#astm_LeaseLiability" xlink:label="loc_astm_LeaseLiability_C7E12229A0B5D8FD93C78F4F0E59BB41_B19F4675B6FD6B7D4EA779444EC87023" xlink:type="locator" />
    <link:calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_astm_LeaseLiabilityPaymentsDue_C7E12229A0B5D8FD93C78F4F0E59BB41_5B5F2379C887F3463B687943604B98DD" xlink:to="loc_astm_LeaseLiability_C7E12229A0B5D8FD93C78F4F0E59BB41_B19F4675B6FD6B7D4EA779444EC87023" xlink:type="arc" />
  </link:calculationLink>
  <link:calculationLink xlink:role="http://www.vcel.com/role/LeasesNotes" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/LeasesSchedulePriorToAdoptionDetails" xlink:type="extended">
    <link:loc xlink:href="astm-20190331.xsd#astm_OperatingandCapitalLeasesandPurchaseCommitmentsFutureMinimumPaymentsDue" xlink:label="loc_astm_OperatingandCapitalLeasesandPurchaseCommitmentsFutureMinimumPaymentsDue_f10e0b4a-e256-3de1-5775-3d9bc511eb5b" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDue" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDue_30d028f9-2f3a-4a0c-02f8-ea9552d875b6" xlink:type="locator" />
    <link:calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_astm_OperatingandCapitalLeasesandPurchaseCommitmentsFutureMinimumPaymentsDue_f10e0b4a-e256-3de1-5775-3d9bc511eb5b" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDue_30d028f9-2f3a-4a0c-02f8-ea9552d875b6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent_f67237f3-7c78-8a5c-b7b3-17f1eb0b017a" xlink:type="locator" />
    <link:calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDue_30d028f9-2f3a-4a0c-02f8-ea9552d875b6" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent_f67237f3-7c78-8a5c-b7b3-17f1eb0b017a" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears_ccaff3fc-3d87-e58a-0083-69dda0c10f9d" xlink:type="locator" />
    <link:calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDue_30d028f9-2f3a-4a0c-02f8-ea9552d875b6" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears_ccaff3fc-3d87-e58a-0083-69dda0c10f9d" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears_39e76369-4fdc-9d5f-860a-45d0795e5fb0" xlink:type="locator" />
    <link:calculationArc order="3" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDue_30d028f9-2f3a-4a0c-02f8-ea9552d875b6" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears_39e76369-4fdc-9d5f-860a-45d0795e5fb0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFourYears" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFourYears_fe404cae-7fcc-3489-844f-4d90e9776180" xlink:type="locator" />
    <link:calculationArc order="4" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDue_30d028f9-2f3a-4a0c-02f8-ea9552d875b6" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFourYears_fe404cae-7fcc-3489-844f-4d90e9776180" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFiveYears" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFiveYears_5b651b24-1278-4eab-c840-7002c6d68546" xlink:type="locator" />
    <link:calculationArc order="5" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDue_30d028f9-2f3a-4a0c-02f8-ea9552d875b6" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFiveYears_5b651b24-1278-4eab-c840-7002c6d68546" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDueThereafter" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueThereafter_36c616b1-40de-90d4-3c05-7e224ce1169a" xlink:type="locator" />
    <link:calculationArc order="6" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDue_30d028f9-2f3a-4a0c-02f8-ea9552d875b6" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueThereafter_36c616b1-40de-90d4-3c05-7e224ce1169a" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CapitalLeasesFutureMinimumPaymentsDue" xlink:label="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDue_3fe38eda-4456-a563-4395-a5a37d278f3f" xlink:type="locator" />
    <link:calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_astm_OperatingandCapitalLeasesandPurchaseCommitmentsFutureMinimumPaymentsDue_f10e0b4a-e256-3de1-5775-3d9bc511eb5b" xlink:to="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDue_3fe38eda-4456-a563-4395-a5a37d278f3f" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CapitalLeasesFutureMinimumPaymentsDueCurrent" xlink:label="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueCurrent_9ab26f2b-d83e-1c3d-e690-2dde044c94a1" xlink:type="locator" />
    <link:calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDue_3fe38eda-4456-a563-4395-a5a37d278f3f" xlink:to="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueCurrent_9ab26f2b-d83e-1c3d-e690-2dde044c94a1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CapitalLeasesFutureMinimumPaymentsDueInTwoYears" xlink:label="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueInTwoYears_fd7e67d9-87c3-7778-6bc0-5545f2d4ac3e" xlink:type="locator" />
    <link:calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDue_3fe38eda-4456-a563-4395-a5a37d278f3f" xlink:to="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueInTwoYears_fd7e67d9-87c3-7778-6bc0-5545f2d4ac3e" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CapitalLeasesFutureMinimumPaymentsDueInThreeYears" xlink:label="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueInThreeYears_a8e23163-8414-ea7e-80b9-68a6b093b7ba" xlink:type="locator" />
    <link:calculationArc order="3" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDue_3fe38eda-4456-a563-4395-a5a37d278f3f" xlink:to="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueInThreeYears_a8e23163-8414-ea7e-80b9-68a6b093b7ba" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CapitalLeasesFutureMinimumPaymentsDueInFourYears" xlink:label="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueInFourYears_9c06b161-1916-c449-ccf9-dc1e39d72edf" xlink:type="locator" />
    <link:calculationArc order="4" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDue_3fe38eda-4456-a563-4395-a5a37d278f3f" xlink:to="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueInFourYears_9c06b161-1916-c449-ccf9-dc1e39d72edf" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CapitalLeasesFutureMinimumPaymentsDueInFiveYears" xlink:label="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueInFiveYears_1c0af884-3189-dce4-5783-6a4f6cbd4182" xlink:type="locator" />
    <link:calculationArc order="5" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDue_3fe38eda-4456-a563-4395-a5a37d278f3f" xlink:to="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueInFiveYears_1c0af884-3189-dce4-5783-6a4f6cbd4182" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CapitalLeasesFutureMinimumPaymentsDueThereafter" xlink:label="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueThereafter_fab6c2dc-4703-7e05-c969-94eac4760773" xlink:type="locator" />
    <link:calculationArc order="6" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDue_3fe38eda-4456-a563-4395-a5a37d278f3f" xlink:to="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueThereafter_fab6c2dc-4703-7e05-c969-94eac4760773" xlink:type="arc" />
    <link:loc xlink:href="astm-20190331.xsd#astm_OperatingandCapitalLeasesandPurchaseCommitmentsFutureMinimumPaymentsDueCurrent" xlink:label="loc_astm_OperatingandCapitalLeasesandPurchaseCommitmentsFutureMinimumPaymentsDueCurrent_2cfe3e1e-935d-0a73-113d-3d9bc508da2b" xlink:type="locator" />
    <link:calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_astm_OperatingandCapitalLeasesandPurchaseCommitmentsFutureMinimumPaymentsDueCurrent_2cfe3e1e-935d-0a73-113d-3d9bc508da2b" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent_f67237f3-7c78-8a5c-b7b3-17f1eb0b017a" xlink:type="arc" />
    <link:calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_astm_OperatingandCapitalLeasesandPurchaseCommitmentsFutureMinimumPaymentsDueCurrent_2cfe3e1e-935d-0a73-113d-3d9bc508da2b" xlink:to="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueCurrent_9ab26f2b-d83e-1c3d-e690-2dde044c94a1" xlink:type="arc" />
    <link:loc xlink:href="astm-20190331.xsd#astm_OperatingandCapitalLeasesandPurchaseCommitmentsFutureMinimumPaymentsDueInTwoYears" xlink:label="loc_astm_OperatingandCapitalLeasesandPurchaseCommitmentsFutureMinimumPaymentsDueInTwoYears_266ebfac-a22c-637f-0d8c-3d9bc50d1a9c" xlink:type="locator" />
    <link:calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_astm_OperatingandCapitalLeasesandPurchaseCommitmentsFutureMinimumPaymentsDueInTwoYears_266ebfac-a22c-637f-0d8c-3d9bc50d1a9c" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears_ccaff3fc-3d87-e58a-0083-69dda0c10f9d" xlink:type="arc" />
    <link:calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_astm_OperatingandCapitalLeasesandPurchaseCommitmentsFutureMinimumPaymentsDueInTwoYears_266ebfac-a22c-637f-0d8c-3d9bc50d1a9c" xlink:to="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueInTwoYears_fd7e67d9-87c3-7778-6bc0-5545f2d4ac3e" xlink:type="arc" />
    <link:loc xlink:href="astm-20190331.xsd#astm_OperatingandCapitalLeasesandPurchaseCommitmentsFutureMinimumPaymentsDueInThreeYears" xlink:label="loc_astm_OperatingandCapitalLeasesandPurchaseCommitmentsFutureMinimumPaymentsDueInThreeYears_dc4076d5-f495-9832-5d10-3d9bc57e6af2" xlink:type="locator" />
    <link:calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_astm_OperatingandCapitalLeasesandPurchaseCommitmentsFutureMinimumPaymentsDueInThreeYears_dc4076d5-f495-9832-5d10-3d9bc57e6af2" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears_39e76369-4fdc-9d5f-860a-45d0795e5fb0" xlink:type="arc" />
    <link:calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_astm_OperatingandCapitalLeasesandPurchaseCommitmentsFutureMinimumPaymentsDueInThreeYears_dc4076d5-f495-9832-5d10-3d9bc57e6af2" xlink:to="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueInThreeYears_a8e23163-8414-ea7e-80b9-68a6b093b7ba" xlink:type="arc" />
    <link:loc xlink:href="astm-20190331.xsd#astm_OperatingandCapitalLeasesandPurchaseCommitmentsFutureMinimumPaymentsDueInFourYears" xlink:label="loc_astm_OperatingandCapitalLeasesandPurchaseCommitmentsFutureMinimumPaymentsDueInFourYears_96be16d4-2d49-e924-b5fa-3d9bc5992662" xlink:type="locator" />
    <link:calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_astm_OperatingandCapitalLeasesandPurchaseCommitmentsFutureMinimumPaymentsDueInFourYears_96be16d4-2d49-e924-b5fa-3d9bc5992662" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFourYears_fe404cae-7fcc-3489-844f-4d90e9776180" xlink:type="arc" />
    <link:calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_astm_OperatingandCapitalLeasesandPurchaseCommitmentsFutureMinimumPaymentsDueInFourYears_96be16d4-2d49-e924-b5fa-3d9bc5992662" xlink:to="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueInFourYears_9c06b161-1916-c449-ccf9-dc1e39d72edf" xlink:type="arc" />
    <link:loc xlink:href="astm-20190331.xsd#astm_OperatingandCapitalLeasesandPurchaseCommitmentsFutureMinimumPaymentsDueinFiveYears" xlink:label="loc_astm_OperatingandCapitalLeasesandPurchaseCommitmentsFutureMinimumPaymentsDueinFiveYears_fe951d98-ae6c-1166-7d17-58bd98159332" xlink:type="locator" />
    <link:calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_astm_OperatingandCapitalLeasesandPurchaseCommitmentsFutureMinimumPaymentsDueinFiveYears_fe951d98-ae6c-1166-7d17-58bd98159332" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFiveYears_5b651b24-1278-4eab-c840-7002c6d68546" xlink:type="arc" />
    <link:calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_astm_OperatingandCapitalLeasesandPurchaseCommitmentsFutureMinimumPaymentsDueinFiveYears_fe951d98-ae6c-1166-7d17-58bd98159332" xlink:to="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueInFiveYears_1c0af884-3189-dce4-5783-6a4f6cbd4182" xlink:type="arc" />
    <link:loc xlink:href="astm-20190331.xsd#astm_OperatingandCapitalLeasesandPurchaseCommitmentsFutureMinimumPaymentsDueThereafter" xlink:label="loc_astm_OperatingandCapitalLeasesandPurchaseCommitmentsFutureMinimumPaymentsDueThereafter_a2c1329c-115f-6496-0692-3d9bc59194c9" xlink:type="locator" />
    <link:calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_astm_OperatingandCapitalLeasesandPurchaseCommitmentsFutureMinimumPaymentsDueThereafter_a2c1329c-115f-6496-0692-3d9bc59194c9" xlink:to="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueThereafter_36c616b1-40de-90d4-3c05-7e224ce1169a" xlink:type="arc" />
    <link:calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_astm_OperatingandCapitalLeasesandPurchaseCommitmentsFutureMinimumPaymentsDueThereafter_a2c1329c-115f-6496-0692-3d9bc59194c9" xlink:to="loc_us-gaap_CapitalLeasesFutureMinimumPaymentsDueThereafter_fab6c2dc-4703-7e05-c969-94eac4760773" xlink:type="arc" />
  </link:calculationLink>
  <link:calculationLink xlink:role="http://www.vcel.com/role/LeasesTables" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/NetLossPerCommonShare" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/NetLossPerCommonShareDetails" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/NetLossPerCommonShareTables" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/Organization" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/OrganizationDetails" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/RecentAccountingPronouncements" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/RecentAccountingPronouncementsPolicies" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/Revenue" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/RevenueConcentrationOfCreditRiskDetails" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/RevenueRevenueByProductAndCustomerDetails" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/RevenueTables" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/SelectedBalanceSheetComponents" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/SelectedBalanceSheetComponentsAccruedExpensesDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent" xlink:label="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent_BC48AF7261415BB6A5B32442866187D8" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccruedBonusesCurrentAndNoncurrent" xlink:label="loc_us-gaap_AccruedBonusesCurrentAndNoncurrent_6ACC5B818351501687A9180ED05C3BF6" xlink:type="locator" />
    <link:calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent_BC48AF7261415BB6A5B32442866187D8" xlink:to="loc_us-gaap_AccruedBonusesCurrentAndNoncurrent_6ACC5B818351501687A9180ED05C3BF6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeRelatedLiabilitiesCurrent" xlink:label="loc_us-gaap_EmployeeRelatedLiabilitiesCurrent_3A57253C36A5540E919CE488D01CFFCC" xlink:type="locator" />
    <link:calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent_BC48AF7261415BB6A5B32442866187D8" xlink:to="loc_us-gaap_EmployeeRelatedLiabilitiesCurrent_3A57253C36A5540E919CE488D01CFFCC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherAccruedLiabilitiesCurrent" xlink:label="loc_us-gaap_OtherAccruedLiabilitiesCurrent_7CB2A760FAD054C1BBF3A62FC7F6BACC" xlink:type="locator" />
    <link:calculationArc order="3" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent_BC48AF7261415BB6A5B32442866187D8" xlink:to="loc_us-gaap_OtherAccruedLiabilitiesCurrent_7CB2A760FAD054C1BBF3A62FC7F6BACC" xlink:type="arc" />
  </link:calculationLink>
  <link:calculationLink xlink:role="http://www.vcel.com/role/SelectedBalanceSheetComponentsInventoryDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InventoryNet" xlink:label="loc_us-gaap_InventoryNet_5E74E35F18385B9895E955433B041651" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InventoryRawMaterials" xlink:label="loc_us-gaap_InventoryRawMaterials_F6C449AC35E857EF955527B88EB9EDBD" xlink:type="locator" />
    <link:calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InventoryNet_5E74E35F18385B9895E955433B041651" xlink:to="loc_us-gaap_InventoryRawMaterials_F6C449AC35E857EF955527B88EB9EDBD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InventoryWorkInProcess" xlink:label="loc_us-gaap_InventoryWorkInProcess_EF6E43DEDC4752358D23089904A35B2B" xlink:type="locator" />
    <link:calculationArc order="2" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InventoryNet_5E74E35F18385B9895E955433B041651" xlink:to="loc_us-gaap_InventoryWorkInProcess_EF6E43DEDC4752358D23089904A35B2B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InventoryFinishedGoods" xlink:label="loc_us-gaap_InventoryFinishedGoods_BE9D77EA08985AB284628D610E0EEFB9" xlink:type="locator" />
    <link:calculationArc order="3" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InventoryNet_5E74E35F18385B9895E955433B041651" xlink:to="loc_us-gaap_InventoryFinishedGoods_BE9D77EA08985AB284628D610E0EEFB9" xlink:type="arc" />
  </link:calculationLink>
  <link:calculationLink xlink:role="http://www.vcel.com/role/SelectedBalanceSheetComponentsPropertyAndEquipmentDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_f37ad080-c77a-efc5-c936-389b16abc420" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_78662f7f-2a6a-5d68-ba8a-7947ed287be5" xlink:type="locator" />
    <link:calculationArc order="1" weight="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNet_f37ad080-c77a-efc5-c936-389b16abc420" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_78662f7f-2a6a-5d68-ba8a-7947ed287be5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_0a08cda9-11b3-e7ac-3fc9-3a23c67d9b96" xlink:type="locator" />
    <link:calculationArc order="2" weight="-1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNet_f37ad080-c77a-efc5-c936-389b16abc420" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_0a08cda9-11b3-e7ac-3fc9-3a23c67d9b96" xlink:type="arc" />
  </link:calculationLink>
  <link:calculationLink xlink:role="http://www.vcel.com/role/SelectedBalanceSheetComponentsTables" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/StockBasedCompensation" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/StockBasedCompensationDetails" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/StockBasedCompensationNonCashStockBasedCompensationExpenseDetails" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/StockBasedCompensationTables" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/StockPurchaseWarrants" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/StockPurchaseWarrantsDetails" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/StockPurchaseWarrantsTables" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/SubsequentEvents" xlink:type="extended" />
  <link:calculationLink xlink:role="http://www.vcel.com/role/SubsequentEventsDetails" xlink:type="extended" />
</link:linkbase>