Brain stem cells are not rejected when transplanted

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日期: 2003-07-15 今日/总浏览: 1/584
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) X! ~: z( `; }Forthefirsttimescientistshaveshownthatbrainstemcellsareimmuneprivileged,whichmeansthattheyareinvisibletoatransplantrecipient'simmunesystemanddonottriggertheimmunesystemtorejectthem.Theseresults,publishedintheJulyissueofStemCells,indicatethatusingcentralnervoussystemstemcellsintransplantsfordiseasesoftheeye(whichispartofthebrain),brain,andspinalcord,mayeliminatetheneedfortissuetypingbefore,andimmunosuppressivedrugsafter,transplantation.Ultimatelythesefindingspromisetoimprovethesuccessofretinaltransplantationtoregeneratevisionformillionswithmaculardegeneration,retinitispigmentosaanddiabeticretinopathyandbraintransplantstorestorefunctioningforpatientswithdisorderssuchasParkinson'sdisease.
' k. P2 H+ ?  ~0 D) o+ K) I7 n; ]Thesefindingsareveryexciting,saysMichaelYoung,PhD,theleadauthorofthestudyandanassistantscientistatSchepensEyeResearchInstituteandassistantprofessoratHarvardMedicalSchool.Thoughwesuspectedbrainstemcellsmightbeprotectedinthisway,thisisthefirstdocumentedevidence.
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& z" n5 R: A( C) Q, j  U! KMosttissueswhentransplantedfromonebodytoanotherareseenbytherecipientasforeignandattackedbytheimmunesystem.Thisisbecausethetransplantedtissuehasmoleculesonitssurfacecalledantigensthatarerecognizedbytheimmunesystemasnotself.Iftheimmuneresponsegoesuncheckedbydrugstoinhibittheattack,itwilleventuallydestroythetransplantedtissueandrejectit.
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Therearesitesinthebodythatdonotmountattacksagainstforeigntissuebecausetodosowouldbetooself-destructive.Forinstance,intheeyeanalloutimmuneattackwouldcauseinflammationthatwoulddestroydelicatetissueand,withit,vision.Thesesites,whichareknownasimmuneprivileged,includetheeye,thebrain,thedigestivesystem,andthereproductivesystem.
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& c4 h: c+ L/ z' V) XYoung,whoinpreviousresearchfoundthatbrainandretinalstemcellstransplantedintotheeyesofmiceandratsseemedtosurvivelongerandintegratemoreeasilyintodamagedretinasthanothercells,suspectedthattheseneuralstemcellsmightbeimmuneprivileged.Theonlywayforhimtolearnthetruenatureoftheirimmunepropertieswastotransplanttheseneuralstemcellstoapartoftherecipientsbodythat,unliketheeye,wasnotimmuneprivilegedalready.
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Heandhiscolleagueschoseapartofthebodythatalwaysrejectstransplantedtissuewithoutimmunosuppressantdrugsandwithoutclosetissuetyping?thekidneycapsule,thepouchinwhichthekidneyislocated.Thispouchiscommonlyusedtodeterminewhethertransplantscansurvive.Overtheyearsscientistshavetestedskin,corneaandothertissuesinthekidneycapsuletoevaluatetheirtransplantpotential.
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! o+ b+ z. L! l' E) a0 e" cYoungandhiscolleaguestookbrainstemcellsfromgreenmice(miceinwhichthegeneforgreenproteinfoundinjellyfishhasbeeninserted)andplacedthemunderthekidneycapsuleinothernormalnon-greenmice.After4weeks,theteamexaminedthemiceandfoundthatthestemcellshadnotbeenrejectedinanyofthemice,and,infact,hadgrownintoneuraltissue.6 _* c, \6 I/ Z* d
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Theyconcludedthattheseneuralstemscellsdidnotinduceanimmuneresponseandmustbeinvisibletotheimmunesystem,atleastinitially.Thenextstepwastodetermineifthecellspossessedtheantigensthatmostothertissueshad.Totestthistheory,theteamtookotherbraincells(notstemcells)fromthegreenmiceandimplantedtheminthenormalnon-greenmice.Thesecellswererejected,andwhenbrainstemcellswerethenagainimplantedinthenormalnon-greenmice,they,toowererejected.Theteamconcluded,therefore,thatthebrainstemcellsdidpossessantigens,butunlesstherecipientwasprimedorpre-immunized,theantigenswerenotvisibletotheimmunesystemoftherecipientandnotrejected.
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Understandingtheimmunepropertiesofthesestemcellscouldhaveanenormouseffectonhowweperformbrainorretinaltransplantationsinthefuture.Stemcellsalreadyhavetheadvantageofbeingabletotransformordifferentiateintovarioustypesofcellsandcanbereproducedendlesslyoutsidethebody.Nowweknowthatatleastbrainstemcellsareimmuneprivilegedandcanbeusedwithoutthesameworryabouttissuematchingorimmunosuppressionthatistrueforothertypesoftissue.YoungisthedirectorofSchepensEyeResearchInstitute'sMindadeGunzburgRetinalTransplantationResearchCenter.Thecenteriscommitted,withafocusonretinalregeneration,tounlockingthemysteriesofvisionandfindingthecuresforblindingeyediseasesthatdevastatemillionsintheUnitedStatesandaroundtheworld.' P% t  _9 T7 Y! `
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Thestudy,titledNeuralprogenitorcellslackimmunogenicityandresistdestructionasallograftscanbeobtainedattheStemsCellswebsiteathttp://stemcells.alphamedpress.org/,orbyemailingpattijacobs@hotmail.comormikey@vision.eri.harvard.edu.
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) C6 ?5 f+ A) j9 w  D5 k. cOthermembersoftheresearchteamincludeJunkoHori,TatFongNg,MarieShatos,andJ.WayneStreileinofSchepensEyeResearchInstituteofBostonandHenryKlassenoftheStemCellResearchProgramatChildren'sHospitalofOrangeCountyinOrange,California.
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2 u8 o  `7 {8 D1 G# l- gSchepensEyeResearchInstituteisanaffiliateofHarvardMedicalSchoolandisthelargestindependenteyeresearchinstituteintheworld.6 F5 j) B. c# t% o/ b6 C8 r5 G

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来源: Schepens Eye Research Institute) O$ Q( d! q+ J" \' f8 u7 R: T' T
发布者: 亦云