干細(xì)胞（英文版）

EmbryonicStemCellsAnintroductiontothescience,ethicsandlegislationEngage:StemCellsACurriculumResourceforHighSchoolsSponsoredby:Whatisastemcell?StemcellscanbecomeothertypesofcellsStemcellscanalsodivideindefinitely

stemcelllinePluripotentvsmultipotentstemcellsReproducedbyPermissionofProfessorRathjenoftheUniversityofAdelaideEmbryonicvsadultstemcellsEScellsarepluripotentAScellsfoundinsmallamountsthroughoutbodyMostAScellsappeartobemultipotentEScellscomefromICMofblastocystReproducedbypermissionoftheNIHWhyallthefuss?StemcellsmaybeabletoreplacedamagedcellsinthebodyToday:lymphoma,leukemiaFuture?Parkinson’s,Alzheimer’s,diabetes...PromisinganimalstudiesReproducedbypermissionofTheProvidenceJournalCourtesyofTheMichaelJ.FoxFoundationforParkinson’sResearchSourcesofEScellsEScelllinesExcessembryosfromIVFclinicsEmbryoscreatedforresearchbyIVFTherapeuticcloningReproducedbypermissionoftheNIHCloningPurposeoftherapeuticcloningistoharvestEScellsfortreatment

blastocystdestroyedPurposeofreproductivecloningistomakenewperson

blastocystimplantedinuterusReproducedbypermissionoftheNIHEthicaldebateHarvestingEScellsdestroystheblastocyst“Thisismurder”ReproducedbypermissionofDaveCatrowandCopleyNewsServiceEthicaldebate,cont’dEScellresearchrequireshumancellsCouldcreateacommercialmarketforhumancells“Thisdevalueslife”CourtesyofKevinSiers,TheCharlotteObserver?2001Ethicaldebate,cont’d“IfexcessIVFembryosarebeingdiscardedanyway,theyshouldbeputtogooduse”ReprintedbypermissionofChipBokandCreatorsSyndicate,Inc.Ethicaldebate,cont’d“Therapeuticcloningisaslipperyslope-itwillleadtoreproductivecloning”ReproducedbypermissionofGaryMarksteinandCopleyNewsServiceGoverningEScellresearchEthicalissuesinembryonicstemcellresearch

FundamentalmoralcontroversyMoralstatusofhumanembryoPotentialhumanbeingMorethandiscardedcells,e.g.fromcancersurgeryForsome,samemoralstatusaschildFundamentalmoralcontroversyMoralstatusofhumanembryoESSwillproceedinCAControversiesleaveimprintAdditionaldilemmasasresearchproceedsExpectextremescrutinyOutlineoftalkDerivationofstemcelllinesClinicaltrialswithESSOversightbyethicsreviewcommitteesNotdiscussResearchwithexistingstemcelllinesAdultstemcellsEthicalguidelinesInformedconsentConfidentialityDonoharmJusticeEthicalguidelinesConsenttousebiologicalmaterialsReproductivematerials/DNApropagationmayhaveparticularsignificanceViewsonstemcellresearchViewsdiverse,complex,linkedtocorevaluesMayallowonepurposebutnotanother25%oocytedonorsnotallowresearch“Wouldn’thaveconsentedifIhadknown…”QuestionsaboutconsentWhoshouldconsent?Whatlevelofconsent?Science2003;301:150FertilityandSterility2004;82:559Whoshouldgiveconsent?CoupleorwomanundergoingARTGametedonorsEggdonors--opportunitiesforconsentSpermdonors--littleinteractionWhatlevelofconsent?Generalconsentto“research”MaynotbeinformedSpecifictypesofcontroversialresearchEmbryonicstemcellsNucleartransferChimeras/hybridsWhatlevelofconsent?Consenttoallfutureresearch?ReviewedbypeersandbyIRBContemporaryconsentpreferableDoessupplymatchresearchdemand?ExceptionstoresearchconsentCommonRuledoesnotapplyifInformationnotindividuallyidentifiableAnonymizationofsamplesacceptablefordiscardedcancertissueEthicalmaybestricterthanlegalEthicalguidelinesRespectconfidentialityParticularlyprivateissueNotabsoluteprincipleMaywanttorecontactgametedonorstopreventharmEthicalguidelinesPreventharmtotransplantrecipientNewhealthconditionindonormayhavesafetyimplications--e.g.cancerMayseekadditionaltestsondonorsMustbebalancedagainstconfidentialityEthicalguidelinesPreventharmtogametedonorMayfindgeneticabnormalityValidity,clinicalsignificance?Precedentsfromgeneticcounseling--notrevealnon-paternity,researchtestsStemcelladvocatetriestoplugProp.71holesSenatorwantsstatetogetportionofpatentroyaltiesEthicalguidelinesJusticeasreciprocity(publicfunding)Whatisowedtopublic?JustificationofethicsapprovalPatentsandlicensesshouldnotundulyrestrictfutureresearchEthicalguidelinesJusticeasreciprocityPublicationofresultsWithpeer-reviewNegativefindingsStatesharepatentrevenuesAccesstotherapyMakereasonable,goodfaitheffortstomakeavailabletothoseinneedHowdoesstemcelltransplantationdifferfromotherclinicaltrials?HeightenedtherapeuticmisconceptionExtensivepublicity,hopeCompellingscientificrationaleHowdoesstemcelltransplantationdifferfromotherclinicaltrials?ConcernaboutspecificadverseeventsDifferentiateintounintendedtissuesMalignancyunderimmunosuppressionStemcelltransplantsworsenedParkinson’sEmbryonicdopaminergicneuronsTransplantsfunctionedNoimprovementinclinicaloutcomesLatedisablingdyskinesiasin15%NEJM2001;344:710StemcelltransplantsworsenedParkinson’sTissue-specificfunctiononlyfirststepPhysiologicleveloffunctionFeedbackregulationInformedconsentforclinicaltrial:

recommendationsInformationtodiscuss:NevertriedinhumansGoalofPhase1issafetyDon’tknowwhetherwillworkinhumansLabandanimalresultsmaynotholdUnknownrisksTestofunderstandingQuestionsaboutlocalIRBreviewTime?Independencefromresearchers?ExpertiseandexperiencewithtopicScientificaswellasethicalissuesPrecedentsforadditionalreviewRecombinantDNAAdvisoryCommittee(RAC)forgenetransferprotocolsIntegratedscienceandethicsreviewPublicmeetingsRACexperienceIspreclinicaldataadequate?SuggesthowtoreduceriskAdditionaltestsformonitoringAEsMoretimebetweensubjectsorgroupsRescueor“suicide”strategyConsentprocess--tendtooverstatebenefitsUCSFOESCRcommitteeMarcelleCedars,MDElenaGates,MDRobTaylor,MD,PhDRickWagner,MAMaryandAdamWeurthLeslieWolf,JD,MPHKeithYamamoto,PhDSuggestionsExpectcontroversyandscrutinyThoroughethicsandsciencereviewRobustconsentprocessMakereasoningtransparentOtherethicalissuesinderivationPatentingofstemcelllinesReligiousobjectionsto“patentinglife”BroadpatentsandrestrictivelicensesmayimpederesearchUseofSCNTforresearchKeeptechnologyfromuseinreproductionAnimal/humanhybridsResearchusesofsuchlinesAnimalmodelsforhumandiseasesTesttherapyinanimalsbeforetryinginhumansAnimal/humanhybridsMoralconcerns“Moralrepugnance”CrossingnaturalspeciesbarriersNotrespecthumandignityMaybeinsupportersofESSNeedtobeaddressedHematopoiesis

frompluripotentstemcellsto

mature,differentiated,

cellulareffectorsofimmunity

andmore

RichardA.PoirierforHHMI/HarvardImmunologySummerProject2004

Clickononeofthefollowingeffectorcellstoseethesequenceofdifferentcellsthatleadtoitsproduction

Th-HelperCellBCellMacrophageNeutrophil

(alternativepath)MastCellPlateletsTcCytotoxicCellDendriticCellNeutrophilEosinophilBasophilErythrocyteT-helpercellpathway

PluripotentStemCell

Thisistheundifferentiatedprecursortoallofthebloodcells,redandwhite,andotherimmuneeffectorcells,andplatelets.

LymphoidStemCell

DaughtercellofthePluripotentStemCell,thiscellwilldividetoproduceprogenitorstoeitherBcellorTcelllines

.

Tcellprogenitor

leavesthebonemarrowandsettlesinthethymus;willproduceThymocytecellsinthethymuswhichcan,inturndifferentiateintoThelpercells,Tkillercells,orTmemorycellsTheThymocyteislocatedinthethymusanddividestoproducematureTeffectorcells…..

Th(helper)Tc(cytotoxic-killer)orTm(memory)

Th(helper)cell…whenactivatedbyanAntigenPresentingCelllikeamacrophagewithantigen,theThcellwillinducerapidgrowthofwhitebloodcellswhichhelpfightinfectionClickHEREtoreturntomenuTc(cytotoxic/”killer”)cellpathwayPluripotentStemCell

Thisistheundifferentiatedprecursortoallofthebloodcells,redandwhite,andotherimmuneeffectorcells,andplatelets.

LymphoidStemCell

DaughtercellofthePluripotentStemCell,thiscellwilldividetoproduceprogenitorstoeitherBcellorTcelllines

.

Tcellprogenitor

leavesthebonemarrowandsettlesinthethymus;willproduceThymocytecellsinthethymuswhichcan,inturndifferentiateintoThelpercells,Tkillercells,orTmemorycellsTheThymocyteislocatedinthethymusanddividestoproducematureTeffectorcells…..

Th(helper)Tc(cytotoxic-killer)orTm(memory)

Tc(cytotoxicor“killer”)Cells…

SometimescalledCTLs(cytotoxicTlymphocytes,thesemayrecognizeinfected“self”cellsanddestroythem.ClickHEREtoreturntomenuBcellpathwayPluripotentStemCell

Thisistheundifferentiatedprecursortoallofthebloodcells,redandwhite,andotherimmuneeffectorcells,andplatelets.

LymphoidStemCell

DaughtercellofthePluripotentStemCell,thiscellwilldividetoproduceprogenitorstoeitherBcellorTcelllines

.

BCellprogenitor…foundinthebonemarrowofhighervertebratesandtheBursaofFabriciusinbirds,thesecellswillproduceantibodyproducingBcells.BCells…

thesearefoundinthebloodand,whenactivatedwillproduceantibodiesagainstparticularantigens.Eachcellproducesantigenspecificantibodiesofonlyonetype.ClickHEREtoreturntomenuDendriticcellpathwayPluripotentStemCell

Thisistheundifferentiatedprecursortoallofthebloodcells,redandwhite,andotherimmuneeffectorcells,andplatelets.

MyeloidStemCells…

daughtersofthePluripotentStemCells,thesearetheprogenitorsofahostofspecializedwhitebloodcells(WBCs),redbloodcells(RBCs)andthebloodplateletswhicharecrucialtobloodclotting.Granulocyte-MonocyteProgenitorcellscandifferentiateintomonocytesorneutrophilsMonocytes…

actasantigenpresentingcells(APCs),asAntibody-DependentCytotoxicCells(ADCC),andpromoteinflammation.DendriticCell…likethemacrophage,thiscellisphagocyticitinhabitsthetissueslookingforforeignintruderstodevour.ClickHEREtoreturntomenuMacrophagepathwayPluripotentStemCell

Thisistheundifferentiatedprecursortoallofthebloodcells,redandwhite,andotherimmuneeffectorcells,andplatelets.

MyeloidStemCells…

daughtersofthePluripotentStemCells,thesearetheprogenitorsofahostofspecializedwhitebloodcells(WBCs),redbloodcells(RBCs)andthebloodplateletswhicharecrucialtobloodclotting.Granulocyte-MonocyteProgenitorcellscandifferentiateintomonocytesorneutrophilsMonocytes…

actasantigenpresentingcells(APCs),asAntibody-DependentCytotoxicCells(ADCC),andpromoteinflammation.Macrophage…functionsasantigenpresentingcell(APC),ininflammation,andinADCC(antibody-dependentcell-mediatedcytotoxicity

ClickHEREtoreturntomenuNeutrophilPathwayPluripotentStemCell

Thisistheundifferentiatedprecursortoallofthebloodcells,redandwhite,andotherimmuneeffectorcells,andplatelets.

MyeloidStemCells…

daughtersofthePluripotentStemCells,thesearetheprogenitorsofahostofspecializedwhitebloodcells(WBCs),redbloodcells(RBCs)andthebloodplateletswhicharecrucialtobloodclotting.Granulocyte-MonocyteProgenitorcellscandifferentiateintomonocytesorneutrophilsMonocytes…

actasantigenpresentingcells(APCs),asAntibody-DependentCytotoxicCells(ADCC),andpromoteinflammation.Neutrophils…functioninantimicrobialactivity,inflammationresponse,andantibody-dependent,cell-mediatedcytotoxicity(ADCC)ClickHEREtoreturntomenuAlternativeNeutrophilpathwayPluripotentStemCell

Thisistheundifferentiatedprecursortoallofthebloodcells,redandwhite,andotherimmuneeffectorcells,andplatelets.

MyeloidStemCells…

daughtersofthePluripotentStemCells,thesearetheprogenitorsofahostofspecializedwhitebloodcells(WBCs),redbloodcells(RBCs)andthebloodplateletswhicharecrucialtobloodclotting.Granulocyte-MonocyteProgenitorcellscandifferentiateintomonocytesorneutrophilsNeutrophils…functioninantimicrobialactivity,inflammationresponse,andantibody-dependent,cell-mediatedcytotoxicity(ADCC)ClickHEREtoreturntomenuEosinophilPathwayPluripotentStemCell

Thisistheundifferentiatedprecursortoallofthebloodcells,redandwhite,andotherimmuneeffectorcells,andplatelets.

MyeloidStemCells…

daughtersofthePluripotentStemCells,thesearetheprogenitorsofahostofspecializedwhitebloodcells(WBCs),redbloodcells(RBCs)andthebloodplateletswhicharecrucialtobloodclotting.EosinophilProgenitor…willproduceeosinophilsEosinophil…thesecellsareactiveintheimmuneresponsetoasthma,allergies,andparasites.ClickHEREtoreturntomenuMastCellPathwayPluripotentStemCell

Thisistheundifferentiatedprecursortoallofthebloodcells,redandwhite,andotherimmuneeffectorcells,andplatelets.

MyeloidStemCells…

daughtersofthePluripotentStemCells,thesearetheprogenitorsofahostofspecializedwhitebloodcells(WBCs),redbloodcells(RBCs)andthebloodplateletswhicharecrucialtobloodclotting.BasophilProgenitor…aproductofthespecializationofMyeloidstemcells,thiscellwillproduceeitherMastCellsorBasophilsMastCell…liketherelatedbasophilsthesecellsfunctionininflammationandallergicresponse.Whenmature,theybecomegranulatedandarefoundintissues,notinperipheralblood.ClickHEREtoreturntomenuBasophilpathwayPluripotentStemCell

Thisistheundifferentiatedprecursortoallofthebloodcells,redandwhite,andotherimmuneeffectorcells,andplatelets.

MyeloidStemCells…

daughtersofthePluripotentStemCells,thesearetheprogenitorsofahostofspecializedwhitebloodcells(WBCs),redbloodcells(RBCs)andthebloodplateletswhicharecrucialtobloodclotting.BasophilProgenitor…aproductofthespecializationofMyeloidstemcells,thiscellwillproduceeitherMastCellsorBasophilsBasophil…thisIgEresponsivecellischaracterizedbycytoplasmicgranuleswhich,whenreleased,functionindestructionofparasitesandalsoinallergicreactions.Thecellreleaseshistamineandplateletactivatorandotherchemicalsignals.ClickHEREtoreturntomenuPlateletpathwayPluripotentStemCell

Thisistheundifferentiatedprecursortoallofthebloodcells,redandwhite,andotherimmuneeffectorcells,andplatelets.

MyeloidStemCells…

daughtersofthePluripotentStemCells,thesearetheprogenitorsofahostofspecializedwhitebloodcells(WBCs),redbloodcells(RBCs)andthebloodplateletswhicharecrucialtobloodclotting.Megakaryocyte…fragmentsintosubcellularpiecescalledplateletsPlatelets…arebloodelementswithoutnucleithatcirculateandareinvolvedinbloodclottingandinflammation.ClickHEREtoreturntomenuErythrocytePathwayPluripotentStemCell

Thisistheundifferentiatedprecursortoallofthebloodcells,redandwhite,andotherimmuneeffectorcells,andplatelets.

MyeloidStemCells…

daughtersofthePluripotentStemCells,thesearetheprogenitorsofahostofspecializedwhitebloodcells(WBCs),redbloodcells(RBCs)andthebloodplateletswhicharecrucialtobloodclotting.ErythroidProgenitor…derivedfromamyeloidstemcell,thisisdestinedtoproducethemostcommonbloodcell,theerythrocyte.Erythrocytes…orredbloodcells(RBCs)areenucleatedcellsthattravelthroughouttheCirculatorySystemandcarryOxygentoallpartsofthebodyviatheabundanthemoglobinfoundwithinthem.

TolearnmoreaboutHematopoiesisclickHERE

Toseeslidesofrealbloodcells,clickHERE

MoralityofStemCellsStemCellsDefinitionofstemcellsStemcellsare“pluripotent”cellsthatcanproducemanydifferentkindsofcells.Afertilizedeggis“omnipotent”,i.e.canproduceallcells.DifferentkindsofstemcellsEmbryonicstemcellscomefromembryos(<6weeks).Stemcellsfromblastocysts(2weeks)arevirtually“immortal”.Fetalstemcellscomefromfetuses(>6weeks)Stemcellsarepresentinsomeadulttissues,includingbrain,spinalcord,andbonemarrow.Embryonicvs.AdultStemCellsEmbryonicstemcellsEmbryoniccellsarepluripotentandvirtuallyimmortal.Embryonicstemcellscanformtumorscalledteratomas.Severalmethodsarenowavailabletocontrolgrowthofembryonicstemcells.AdultstemcellsAdultstemcellsalsohavethecapacitytoproducemanydifferentcelltypes,includingneurons.Aperson’sownstemcellsshouldbethebestsourceofcellsfortransplantationAdultstemcellswilleventuallysubstituteforembryonicstemcells.EmbryonicStemCellsAdaptedfromtheNewYorkTimes18December2001TheStemCellDebateOnAugust9,2001,PresidentGeorgeBushannouncedthatNIHwillfundhumanembryonicstemcell(HESC)researchforthefirsttime.Theresearchwillberestrictedto72celllinesderivedfromsurplusfertilizedembryosbeforeAugust9.BothopponentsandsupportersofHESCresearchareunhappywiththeruling.OpponentsbelievethatfederalfundingofhumanESCresearchwillopenaPandora’sboxleadingtobabyandorganfactories.Supportersbelievethattherestrictionswillholdbackcrucialresearchthatwillbenefitmillionsofpeople.Researchershaverecentlyfoundthattheycancreateclonedembryos.Stemcellsderivedfromsuchembryoshavethesamegenesandareanidealsourceofstemcellsfortransplantation.Congress,however,isconsideringabillthatwouldoutlawmakingofclonedembryonicstemcells.ImportanceofStemCellsStudiesofhumanembryonicstemcellswillleadtomajoradvancesinhumanbiologyEmbryonicstemcellresearchwillprovidecriticalinsightsintomechanismsofcelldifferentiation,growth,anddeath.Understandingstemcellsmayprovidekeystowhypeopleage.Limitationsonthestudyofhumanembryonicstemcellresearchwillholdbackbiomedicalresearch.HumanembryonicstemcelltherapiescansavelivesandrestorefunctionofpeopleHumanembryonicstemcellcanreplacedamagedorlostcellsTheseincludediabetes,degenerativeneurologicaldiseases,demyelinativediseases,brain&spinalcordinjury.TheseconditionsarethemostcommonandcostlycausesofdisabilityintheUnitedStates.OppositiontoHESCResearchKillinghumanembryosisunacceptableUseandstudyofhumanembryonicstemcellswillrequiredestructionofhumanembryos.Killinghumanembryosisunacceptable,nomatterhowmuchgoodsuchresearchwillbringabout.Thefactsthatembryoswilldieanywayandthatmanypeoplewouldbenefitfromthetherapiesdonotjustifykillingembryos.Theenddoesnotjustifythemeans.EmbryonicstemcelltherapiesarenotnecessaryAdultandothersourcesofstemcells,i.e.umbilicalbloodorbonemarrowstemcellscanbeused.ManystudiessuggestthatstemcellsfromthesesourcesarebeneficialinanimaldiseasemodelsEmbryonicstemcellsmayformtumorswhereasadultstemcellshavelimitedgrowthpotentialandarelesslikelytoproducecancers.CommonMisconceptionsHumanembryonicstemcellresearchencouragesabortions.TheproposedNIHresearchwillusefrozenfertilizedeggs,notabortedfetuses.Thefertilizedeggsareusedwithpermissionoftheparentswhowouldotherwisediscardthem.AvailabilityofhumanembryonicstemcellsshouldreducethecurrentneedforanduseofhumanfetaltissuestotreatParkinson’sdiseaseandotherconditions.Theresearchwillincreasekillingofhumanembryos.TheproposedNIHresearchwillnotcreateorclonehumanembryos.Onlyfertilizedeggsthatwerealreadybeencreatedforthepurposesofinvitrofertilizationareused.Availabilityofthissourceofstemcellsshouldreducecurrentunrestrictedcreationanddestructionofhumanembryosfortheirstemcells.MoreMisconceptionsEmbryonicstemcellscomefromembryosthatcanbecomeadultsThousandsoffertilizedeggsarebeingdiscardedfromfertilityandnotbeingusedforresearchortherapyManyfertilizedeggshavebeenstoredbeyondthetimewhentheyaresuitableforproducingembryos.Manyparentsdonotwanttheireggstobe“adopted”byothers.EmbryonicstemcellscomefromembryoswithrecognizablebodypartsEmbryonicstemcellscomefromblastocysts(2weeks),littleroundballsofcellswithnodiscernibleorgansorbodyparts.Theblastocystsareneverimplantedintoauterus.Embryosformonlyafterthenotochordappearsatabout2weeks.Embryosbecomefetusesat6weeks.CurrentSituationCurrentlawsdonotregulateembryoproductionorusebyprivatecompaniesManycompaniesproducestemcellsfromhumanembryoscreatedforthispurpose.Someprivateorganizationsaredevelopingstemcellsfromabortedfetuses.Somecompaniesareevencloninghumanembryostodevelopstemcelllines.Mosthumanembryonicstemlinesbelongtoprivatecompanies.Companiesthereforemustdeveloptheirownlinesiftheywanttodohumanstemcellresearch.A“public”sourceofhumanembryonicstemcellsshouldsignificantlyreducethenumberofembryosthatarecreatedanddestroyedfortheirstemcells.StemCellsvsnon-StemCellsStemcelltherapieswillrevolutionizemedicine.Thecurrentgenerationofdoctorswillbethefirsttousestemcelltransplantstorepairandreplacetissues.Geneticallymodifiedstemcellscandelivermolecules.Forexample,insulin-secretingcellsmayreplacelife-timeinsulininjections.Stemcellsareimportantclassoftransplantablecellsbecausetheyarerobustandproducemanycelltypes.Non-stemcellsmaybebetterforsomepurposesGeneticallymodifiedfibroblasts,forexample,havealreadybeenshowntodelivergeneproductsMixturesofprogenitorcellsthatproduceonlyonekindofcellmaybemoreeasytocontrolthanstemcells.Somespecializedcellsmayhaveadvantagesoverstemcells.Forexample,Sertolicellshaveanti-immuneproperties.SlipperySlopeArgumentsFederalfundingofHESCresearchmayleadtoaslidedownaslipperyslope.Aoft-statedfearisthatembryonicstemcellresearchwillgothewayofabortion.TheUnitedStateswentfromacompletebantoabortionsondemand.Peoplefeelthattherearenosafeguardagainstasimilarslidetowardsa“BraveNewWorld”withembryofarmsandbodypartsforsale.Limitedstemcellavailabilitymayleadtoaslidedownanotherslipperyslope:ThestemcelllinescreatedbeforeAugust9arenotsufficientlyavailablenordiversefortherapyHESCresearchwillcontinueintheprivatesectorandoverseaswhereembryouseisnotregulated.Embryosarebeingcreatedforthepurposeofstemcellproduction.HumanCloninghttp://news.bbc.co.uk/hi/english/sci/tech/newsid_371000/371378.stmFirsthumanclonebyplacinghumannucleusintoacow’seggandgrowingitto32-cellstage.Nov1997ScientificAmericanarticlereportingthe“first”clonedhumanembryoshowingafertilizedclonedoocyteandcumuluscells.AdvancedCellTechnologyNov24,2001/explorations/2001/112401ezzell/TherapeuticCloningClonaidclaimsalsotohavecreatedfirsthumanclonesandplansforreproductivecloning.-CNN,27Nov2001/HEALTH/ReproductivecloningTheprocessofcreatinganindividualorganismthatisgeneticallyidentical.Currentmethodrequiressomaticnucleartransfer(transferofnucleusofasomaticcelltoanoocyte)TherapeuticcloningTheprocessofcreatinggeneticallyidenticalcellsfortherapeuticpurposes.Manymethodscanbeused,includingsomaticnucleartransfer&parthenogenesisReligiousPositionsHumanembryonicstemcellsareimmoralTheCatholicandGreekOrthodoxChurchesbelievethatembryosarepotentialhumans.Evenifembryosarebeingdestroyedforotherreasons,theiruseisimmoral.ResearchanduseofearlyembryosisnotimmoralTheSynod(Protestant)believesthathumanembryonicresearchisnotimmoralifitoccursbeforeimplantationIslamicschoolsdonotrecognizeearlyembryosasmoralpersonsandhavenodifficultywithuseandstudyofthem.Life-savingresearchisamoralobligationTheJewishfaithbelievesthatsavinghumanlivesisamoralobligationandadivinemandateaslongascareistakentoensurethattheprocessisfairtoallpartiesinvolved.PhilosophicalPositionsThe“wisdomofrepugnance”argumentDr.LeonKassappliedthisphrasetotherapeuticcloning,meaningthatweknow,deepdown,thatitisimmoraltocreatehumanembryostousethem.The“sanctityoflife”argumentSomephilosophershaveinvokedthe”sanctityoflife”asanargumentagainstusingembryonicstemcells.Thisreducesthequestiontoourdefinitionoflifeandaperson.The“respectfortheembryo”argumentHumanlifedemandsrespect.Whileitisnotdisrespectfultouseanorganfromadeadperson,somearguethatitisdisrespectfultocreateanembryoandkillitforitsstemcellsU.S.GovernmentPositionsInAugust2000,NIHproposedtofundresearchonhumanembryonicstemcellsobtainedfromexcessfertilizedhumaneggsthatwillbediscardedbyfertilityclinics.Theseembryoswerenotproducedforthepurposesofresearchortherapy.Iftheyarenotusedforresearch,theywouldbediscarded.PresidentBushruledthatNIHcanfundresearchonhumanembryonicstemcellsbutonlycelllinesderivedfromfertilizedembryosbeforeAugust9,2001ThiscompromiseensuresthatnofederalfundingwillsupportdestructionembryosforresearchortherapyPresidentBushstronglyopposeshumancloningorthecreationandkillingembryosforthepurposesofresearchortherapy.NIHhassinceidentifiedabout72humanembryoniccelllinescreatedbeforeAugust9andareeligibleforstudy.U.S.LegislativePositionsH.R.2747StemCellResearchforPatientBenefitActof2001.

NIHresearchwithhumanpluripotentstemcells,restrictedtocelllinesavailablebeforeAugust9.AlsofundsanInstituteofMedicinestudyandestablishesaBiomedicalAdvisoryCommission.S.1349ResponsibleStemCellResearchAct(2001)

$275millionforaNational