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  <xs:element name="WarrantsGrantedWeightedAverageExercisePrice" type="num:perShareItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_WarrantsGrantedWeightedAverageExercisePrice"/>
  <xs:element name="FairValueOfWarrantsAssumptionsAbstract" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_FairValueOfWarrantsAssumptionsAbstract"/>
  <xs:element name="Note13WarrantsDetailsFairValueofWarrantsAssumptionsTable" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrldt:hypercubeItem" id="clsn_Note13WarrantsDetailsFairValueofWarrantsAssumptionsTable"/>
  <xs:element name="Note13WarrantsDetailsFairValueofWarrantsAssumptionsLineItems" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_Note13WarrantsDetailsFairValueofWarrantsAssumptionsLineItems"/>
  <xs:element name="FairValueAssumptionsExpectedForfeitureRate" type="num:percentItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_FairValueAssumptionsExpectedForfeitureRate"/>
  <xs:element name="CommonStockWarrantLiabilityAbstract" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_CommonStockWarrantLiabilityAbstract"/>
  <xs:element name="SummaryOfWaivedWarrantsAbstract" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_SummaryOfWaivedWarrantsAbstract"/>
  <xs:element name="ExpirationDateOfWaivedWarrants" type="xbrli:dateItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_ExpirationDateOfWaivedWarrants"/>
  <xs:element name="PerShareFairValueOfWarrants" type="num:perShareItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item" id="clsn_PerShareFairValueOfWarrants"/>
  <xs:element name="SharesOfCommonStockAssociatedWithWaivedWarrantsAbstract" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_SharesOfCommonStockAssociatedWithWaivedWarrantsAbstract"/>
  <xs:element name="ExpirationDateOfWarrants" type="xbrli:dateItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_ExpirationDateOfWarrants"/>
  <xs:element name="ReverseStockSplitNumberOfSharesOutstandingConsolidatedIntoEachShare" type="xbrli:pureItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item" id="clsn_ReverseStockSplitNumberOfSharesOutstandingConsolidatedIntoEachShare"/>
  <xs:element name="Note5InvestmentSecuritiesAvailableForSaleDetailsTable" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrldt:hypercubeItem" id="clsn_Note5InvestmentSecuritiesAvailableForSaleDetailsTable"/>
  <xs:element name="Note5InvestmentSecuritiesAvailableForSaleDetailsLineItems" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_Note5InvestmentSecuritiesAvailableForSaleDetailsLineItems"/>
  <xs:element name="Note7AcquisitionofEGENIncDetailsTable" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrldt:hypercubeItem" id="clsn_Note7AcquisitionofEGENIncDetailsTable"/>
  <xs:element name="Note7AcquisitionofEGENIncDetailsLineItems" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_Note7AcquisitionofEGENIncDetailsLineItems"/>
  <xs:element name="SharesReservedForContingentConsideration" type="xbrli:sharesItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_SharesReservedForContingentConsideration"/>
  <xs:element name="CapitalLeaseTransactionDomain" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_CapitalLeaseTransactionDomain"/>
  <xs:element name="InvestmentTypeDomain" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_InvestmentTypeDomain"/>
  <xs:element name="Note10NotePayableDetailsTable" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrldt:hypercubeItem" id="clsn_Note10NotePayableDetailsTable"/>
  <xs:element name="Note10NotePayableDetailsLineItems" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_Note10NotePayableDetailsLineItems"/>
  <xs:element name="ClassOfWarrantOrRightPercentExercisableImmediately" type="num:percentItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_ClassOfWarrantOrRightPercentExercisableImmediately"/>
  <xs:element name="ClassOfWarrantOrRightPercentConditionallyExercisable" type="num:percentItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_ClassOfWarrantOrRightPercentConditionallyExercisable"/>
  <xs:element name="LineOfCreditFacilityOriginalLoanFeePercent" type="num:percentItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item" id="clsn_LineOfCreditFacilityOriginalLoanFeePercent"/>
  <xs:element name="LoanTrancheAmount" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item" id="clsn_LoanTrancheAmount"/>
  <xs:element name="NoteStockConversionRate" type="num:percentItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_NoteStockConversionRate"/>
  <xs:element name="WarrantsIssuedExpirationPeriod" type="xbrli:durationItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_WarrantsIssuedExpirationPeriod"/>
  <xs:element name="RelatedTransactionDomain" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_RelatedTransactionDomain"/>
  <xs:element name="CreationDateDomain" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_CreationDateDomain"/>
  <xs:element name="Note11StockholdersEquityDetailsTable" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrldt:hypercubeItem" id="clsn_Note11StockholdersEquityDetailsTable"/>
  <xs:element name="Note11StockholdersEquityDetailsLineItems" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_Note11StockholdersEquityDetailsLineItems"/>
  <xs:element name="CommonStockSharesPerWarrant" type="xbrli:sharesItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item" id="clsn_CommonStockSharesPerWarrant"/>
  <xs:element name="UnitPrice" type="us-types:perUnitItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item" id="clsn_UnitPrice"/>
  <xs:element name="CommissiononProceedsfromATMSharesPercent" type="num:percentItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_CommissiononProceedsfromATMSharesPercent"/>
  <xs:element name="Note12StockBasedCompensationDetailsTable" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrldt:hypercubeItem" id="clsn_Note12StockBasedCompensationDetailsTable"/>
  <xs:element name="Note12StockBasedCompensationDetailsLineItems" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_Note12StockBasedCompensationDetailsLineItems"/>
  <xs:element name="Note13WarrantsDetailsTable" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrldt:hypercubeItem" id="clsn_Note13WarrantsDetailsTable"/>
  <xs:element name="Note13WarrantsDetailsLineItems" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_Note13WarrantsDetailsLineItems"/>
  <xs:element name="ProceedsFromIssuanceOfWarrantsNet" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item" id="clsn_ProceedsFromIssuanceOfWarrantsNet"/>
  <xs:element name="CommonStockAndWarrantsIssuedShares" type="xbrli:sharesItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_CommonStockAndWarrantsIssuedShares"/>
  <xs:element name="CommonStockWarrantsWeightedAverageRemainingContractualTerm" type="xbrli:durationItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_CommonStockWarrantsWeightedAverageRemainingContractualTerm"/>
  <xs:element name="ClassOfWarrantOrRightWaived" type="xbrli:sharesItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item" id="clsn_ClassOfWarrantOrRightWaived"/>
  <xs:element name="ReclassificationFromEquitytoLiability" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item" id="clsn_ReclassificationFromEquitytoLiability"/>
  <xs:element name="CommonStockWarrantLiabilityBenefitfromAdjustmentInWarrantLiability" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item" id="clsn_CommonStockWarrantLiabilityBenefitfromAdjustmentInWarrantLiability"/>
  <xs:element name="ReverseStockSplitReclassificationFromLiabilityToEquity" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item" id="clsn_ReverseStockSplitReclassificationFromLiabilityToEquity"/>
  <xs:element name="Note14ContingentLiabilitiesandCommitmentsDetailsTable" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrldt:hypercubeItem" id="clsn_Note14ContingentLiabilitiesandCommitmentsDetailsTable"/>
  <xs:element name="Note14ContingentLiabilitiesandCommitmentsDetailsLineItems" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_Note14ContingentLiabilitiesandCommitmentsDetailsLineItems"/>
  <xs:element name="NumberOfMonthsInWhichFreeRentIsProvided" type="xbrli:durationItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_NumberOfMonthsInWhichFreeRentIsProvided"/>
  <xs:element name="EscrowDepositRelatedToOperatingLease" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item" id="clsn_EscrowDepositRelatedToOperatingLease"/>
  <xs:element name="ContractualObligationReduction" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item" id="clsn_ContractualObligationReduction"/>
  <xs:element name="ContractualObligationNineteenMonthsFromInitialTerm" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item" id="clsn_ContractualObligationNineteenMonthsFromInitialTerm"/>
  <xs:element name="ContractualObligationThirtyOneMonthsFromInitialTerm" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item" id="clsn_ContractualObligationThirtyOneMonthsFromInitialTerm"/>
  <xs:element name="ContractualObligationFortyThreeMonthsFromInitialTerm" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item" id="clsn_ContractualObligationFortyThreeMonthsFromInitialTerm"/>
  <xs:element name="ContractualObligationRemaining" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item" id="clsn_ContractualObligationRemaining"/>
  <xs:element name="ReductionofEscrowDeposit" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item" id="clsn_ReductionofEscrowDeposit"/>
  <xs:element name="Note15TechnologyDevelopmentandLicensingAgreementsDetailsTable" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrldt:hypercubeItem" id="clsn_Note15TechnologyDevelopmentandLicensingAgreementsDetailsTable"/>
  <xs:element name="Note15TechnologyDevelopmentandLicensingAgreementsDetailsLineItems" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_Note15TechnologyDevelopmentandLicensingAgreementsDetailsLineItems"/>
  <xs:element name="DeferredRevenueAmortizationPeriod" type="xbrli:durationItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_DeferredRevenueAmortizationPeriod"/>
  <xs:element name="PercentageReductionOnMilestonePayments" type="num:percentItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_PercentageReductionOnMilestonePayments"/>
  <xs:element name="CapitalLeaseTransactionAxis" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrldt:dimensionItem" id="clsn_CapitalLeaseTransactionAxis"/>
  <xs:element name="RelatedTransactionAxis" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrldt:dimensionItem" id="clsn_RelatedTransactionAxis"/>
  <xs:element name="ATMAgreementMember" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_ATMAgreementMember"/>
  <xs:element name="AggregateProceedsOf10MillionDollarsMember" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_AggregateProceedsOf10MillionDollarsMember"/>
  <xs:element name="ClosingPricePerShareMember" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_ClosingPricePerShareMember"/>
  <xs:element name="CommittedEquityFinancingFacilityMember" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_CommittedEquityFinancingFacilityMember"/>
  <xs:element name="CommonStockWarrantsMember" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_CommonStockWarrantsMember"/>
  <xs:element name="CorporateBondMaturingBetween3And12MonthsMember" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_CorporateBondMaturingBetween3And12MonthsMember"/>
  <xs:element name="CorporateBondMaturingWithin3MonthsMember" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_CorporateBondMaturingWithin3MonthsMember"/>
  <xs:element name="CreditAgreementMember" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_CreditAgreementMember"/>
  <xs:element name="DominickLLCMember" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_DominickLLCMember"/>
  <xs:element name="EGENIncMember" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_EGENIncMember"/>
  <xs:element name="ExpirationDateRange1Member" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_ExpirationDateRange1Member"/>
  <xs:element name="ExpirationDateRange2Member" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_ExpirationDateRange2Member"/>
  <xs:element name="ExpirationDateRange3Member" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_ExpirationDateRange3Member"/>
  <xs:element name="ExpirationDateRange4Member" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_ExpirationDateRange4Member"/>
  <xs:element name="February2013PreferrdStockOfferingMember" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_February2013PreferrdStockOfferingMember"/>
  <xs:element name="FormerExecutiveOfficersMember" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_FormerExecutiveOfficersMember"/>
  <xs:element name="GlioblastomaMultiformeBrainCancerStudyMilestoneMember" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_GlioblastomaMultiformeBrainCancerStudyMilestoneMember"/>
  <xs:element name="HerculesCreditAgreementMember" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_HerculesCreditAgreementMember"/>
  <xs:element name="HerculesMember" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_HerculesMember"/>
  <xs:element name="January2011PreferredStockOfferingMember" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_January2011PreferredStockOfferingMember"/>
  <xs:element name="LawrencevilleNewJerseyMember" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_LawrencevilleNewJerseyMember"/>
  <xs:element name="MayOfferingMember" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_MayOfferingMember"/>
  <xs:element name="Minimum4DollarSharePriceMember" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_Minimum4DollarSharePriceMember"/>
  <xs:element name="November2011CapitalLeaseMember" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_November2011CapitalLeaseMember"/>
  <xs:element name="OvarianCancerStudyMilestoneMember" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_OvarianCancerStudyMilestoneMember"/>
  <xs:element name="OxfordAndHorizonCreditAgreementMember" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_OxfordAndHorizonCreditAgreementMember"/>
  <xs:element name="OxfordAndHorizonMember" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_OxfordAndHorizonMember"/>
  <xs:element name="PreferedStockMember" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_PreferedStockMember"/>
  <xs:element name="PreferredEquityFinancingMember" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_PreferredEquityFinancingMember"/>
  <xs:element name="RequiresEnrollmentOfPatientsMember" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_RequiresEnrollmentOfPatientsMember"/>
  <xs:element name="ReverseStockSplitMember" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_ReverseStockSplitMember"/>
  <xs:element name="SeriesAConvertiblePreferredStockMember" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_SeriesAConvertiblePreferredStockMember"/>
  <xs:element name="SeriesAWarrantMember" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_SeriesAWarrantMember"/>
  <xs:element name="SeriesBWarrantMember" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_SeriesBWarrantMember"/>
  <xs:element name="ShortTermInvestmentsAvailableForSaleMember" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_ShortTermInvestmentsAvailableForSaleMember"/>
  <xs:element name="StockIncentivePlan2001Member" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_StockIncentivePlan2001Member"/>
  <xs:element name="StockIncentivePlan2004Member" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_StockIncentivePlan2004Member"/>
  <xs:element name="StockIncentivePlan2007Member" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_StockIncentivePlan2007Member"/>
  <xs:element name="TermALoanMember" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_TermALoanMember"/>
  <xs:element name="TheraSilenceTechnologyMilestoneMember" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_TheraSilenceTechnologyMilestoneMember"/>
  <xs:element name="WaivedWarrantMember" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_WaivedWarrantMember"/>
  <xs:element name="WaivedWarrantsMember" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_WaivedWarrantsMember"/>
  <xs:element name="WarrantLiabilityMember" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_WarrantLiabilityMember"/>
  <xs:element name="WarrantsIssuedIn2009RegisteredDirectOfferingMember" type="nonnum:domainItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_WarrantsIssuedIn2009RegisteredDirectOfferingMember"/>
  <xs:element name="DocumentAndEntityInformationAbstract" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="clsn_DocumentAndEntityInformationAbstract"/>
</xs:schema>
