Brain stem cells are not rejected when transplanted

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日期: 2003-07-15 今日/总浏览: 1/584) S9 z2 U* Z+ r, r" S+ X
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$ I+ F9 |# U. g& R  ~  l* ^Forthefirsttimescientistshaveshownthatbrainstemcellsareimmuneprivileged,whichmeansthattheyareinvisibletoatransplantrecipient'simmunesystemanddonottriggertheimmunesystemtorejectthem.Theseresults,publishedintheJulyissueofStemCells,indicatethatusingcentralnervoussystemstemcellsintransplantsfordiseasesoftheeye(whichispartofthebrain),brain,andspinalcord,mayeliminatetheneedfortissuetypingbefore,andimmunosuppressivedrugsafter,transplantation.Ultimatelythesefindingspromisetoimprovethesuccessofretinaltransplantationtoregeneratevisionformillionswithmaculardegeneration,retinitispigmentosaanddiabeticretinopathyandbraintransplantstorestorefunctioningforpatientswithdisorderssuchasParkinson'sdisease.7 i' Q2 i" N- H
Thesefindingsareveryexciting,saysMichaelYoung,PhD,theleadauthorofthestudyandanassistantscientistatSchepensEyeResearchInstituteandassistantprofessoratHarvardMedicalSchool.Thoughwesuspectedbrainstemcellsmightbeprotectedinthisway,thisisthefirstdocumentedevidence.
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* r+ I* D" M! O5 C& [Mosttissueswhentransplantedfromonebodytoanotherareseenbytherecipientasforeignandattackedbytheimmunesystem.Thisisbecausethetransplantedtissuehasmoleculesonitssurfacecalledantigensthatarerecognizedbytheimmunesystemasnotself.Iftheimmuneresponsegoesuncheckedbydrugstoinhibittheattack,itwilleventuallydestroythetransplantedtissueandrejectit.
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! L: c4 M# U1 K( |5 d, A& eTherearesitesinthebodythatdonotmountattacksagainstforeigntissuebecausetodosowouldbetooself-destructive.Forinstance,intheeyeanalloutimmuneattackwouldcauseinflammationthatwoulddestroydelicatetissueand,withit,vision.Thesesites,whichareknownasimmuneprivileged,includetheeye,thebrain,thedigestivesystem,andthereproductivesystem.8 J" _- [# z& |8 r: j; P9 c( Z

* x  l9 \2 R% }- w1 W2 M7 X, k& qYoung,whoinpreviousresearchfoundthatbrainandretinalstemcellstransplantedintotheeyesofmiceandratsseemedtosurvivelongerandintegratemoreeasilyintodamagedretinasthanothercells,suspectedthattheseneuralstemcellsmightbeimmuneprivileged.Theonlywayforhimtolearnthetruenatureoftheirimmunepropertieswastotransplanttheseneuralstemcellstoapartoftherecipientsbodythat,unliketheeye,wasnotimmuneprivilegedalready." ~7 S/ T" G) h  p* |) |" u

5 O) g6 f5 e9 _4 b- r7 EHeandhiscolleagueschoseapartofthebodythatalwaysrejectstransplantedtissuewithoutimmunosuppressantdrugsandwithoutclosetissuetyping?thekidneycapsule,thepouchinwhichthekidneyislocated.Thispouchiscommonlyusedtodeterminewhethertransplantscansurvive.Overtheyearsscientistshavetestedskin,corneaandothertissuesinthekidneycapsuletoevaluatetheirtransplantpotential.5 O/ C5 J0 n3 ~) p. ~
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Youngandhiscolleaguestookbrainstemcellsfromgreenmice(miceinwhichthegeneforgreenproteinfoundinjellyfishhasbeeninserted)andplacedthemunderthekidneycapsuleinothernormalnon-greenmice.After4weeks,theteamexaminedthemiceandfoundthatthestemcellshadnotbeenrejectedinanyofthemice,and,infact,hadgrownintoneuraltissue.& {. u# v% |, {: B0 g+ t1 x+ Z
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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.8 h+ c0 K4 `; m
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Thestudy,titledNeuralprogenitorcellslackimmunogenicityandresistdestructionasallograftscanbeobtainedattheStemsCellswebsiteathttp://stemcells.alphamedpress.org/,orbyemailingpattijacobs@hotmail.comormikey@vision.eri.harvard.edu.
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# y2 k0 s$ V% y' I3 p! h7 y# f1 NOthermembersoftheresearchteamincludeJunkoHori,TatFongNg,MarieShatos,andJ.WayneStreileinofSchepensEyeResearchInstituteofBostonandHenryKlassenoftheStemCellResearchProgramatChildren'sHospitalofOrangeCountyinOrange,California." U1 `9 ]$ o5 h  k. U9 a3 ^
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SchepensEyeResearchInstituteisanaffiliateofHarvardMedicalSchoolandisthelargestindependenteyeresearchinstituteintheworld.
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作者: 4 X. C; t) e" K- A
来源: Schepens Eye Research Institute8 ?; Q8 _4 F( I+ l' Z; f  C' c
发布者: 亦云