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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Forthefirsttimescientistshaveshownthatbrainstemcellsareimmuneprivileged,whichmeansthattheyareinvisibletoatransplantrecipient'simmunesystemanddonottriggertheimmunesystemtorejectthem.Theseresults,publishedintheJulyissueofStemCells,indicatethatusingcentralnervoussystemstemcellsintransplantsfordiseasesoftheeye(whichispartofthebrain),brain,andspinalcord,mayeliminatetheneedfortissuetypingbefore,andimmunosuppressivedrugsafter,transplantation.Ultimatelythesefindingspromisetoimprovethesuccessofretinaltransplantationtoregeneratevisionformillionswithmaculardegeneration,retinitispigmentosaanddiabeticretinopathyandbraintransplantstorestorefunctioningforpatientswithdisorderssuchasParkinson'sdisease.
' `  S5 Q6 b4 w5 o* HThesefindingsareveryexciting,saysMichaelYoung,PhD,theleadauthorofthestudyandanassistantscientistatSchepensEyeResearchInstituteandassistantprofessoratHarvardMedicalSchool.Thoughwesuspectedbrainstemcellsmightbeprotectedinthisway,thisisthefirstdocumentedevidence.
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/ t$ J$ a; e0 s' DMosttissueswhentransplantedfromonebodytoanotherareseenbytherecipientasforeignandattackedbytheimmunesystem.Thisisbecausethetransplantedtissuehasmoleculesonitssurfacecalledantigensthatarerecognizedbytheimmunesystemasnotself.Iftheimmuneresponsegoesuncheckedbydrugstoinhibittheattack,itwilleventuallydestroythetransplantedtissueandrejectit.
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; g" D3 z& Y, t5 f) B4 n& e( J# WTherearesitesinthebodythatdonotmountattacksagainstforeigntissuebecausetodosowouldbetooself-destructive.Forinstance,intheeyeanalloutimmuneattackwouldcauseinflammationthatwoulddestroydelicatetissueand,withit,vision.Thesesites,whichareknownasimmuneprivileged,includetheeye,thebrain,thedigestivesystem,andthereproductivesystem.  d5 s6 q0 S' `6 F4 |
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Young,whoinpreviousresearchfoundthatbrainandretinalstemcellstransplantedintotheeyesofmiceandratsseemedtosurvivelongerandintegratemoreeasilyintodamagedretinasthanothercells,suspectedthattheseneuralstemcellsmightbeimmuneprivileged.Theonlywayforhimtolearnthetruenatureoftheirimmunepropertieswastotransplanttheseneuralstemcellstoapartoftherecipientsbodythat,unliketheeye,wasnotimmuneprivilegedalready.& H0 T! m# `# O7 r
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Heandhiscolleagueschoseapartofthebodythatalwaysrejectstransplantedtissuewithoutimmunosuppressantdrugsandwithoutclosetissuetyping?thekidneycapsule,thepouchinwhichthekidneyislocated.Thispouchiscommonlyusedtodeterminewhethertransplantscansurvive.Overtheyearsscientistshavetestedskin,corneaandothertissuesinthekidneycapsuletoevaluatetheirtransplantpotential.
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0 f& W: }* u0 q# [" `- pYoungandhiscolleaguestookbrainstemcellsfromgreenmice(miceinwhichthegeneforgreenproteinfoundinjellyfishhasbeeninserted)andplacedthemunderthekidneycapsuleinothernormalnon-greenmice.After4weeks,theteamexaminedthemiceandfoundthatthestemcellshadnotbeenrejectedinanyofthemice,and,infact,hadgrownintoneuraltissue.
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0 p8 z: Y; `+ y& PTheyconcludedthattheseneuralstemscellsdidnotinduceanimmuneresponseandmustbeinvisibletotheimmunesystem,atleastinitially.Thenextstepwastodetermineifthecellspossessedtheantigensthatmostothertissueshad.Totestthistheory,theteamtookotherbraincells(notstemcells)fromthegreenmiceandimplantedtheminthenormalnon-greenmice.Thesecellswererejected,andwhenbrainstemcellswerethenagainimplantedinthenormalnon-greenmice,they,toowererejected.Theteamconcluded,therefore,thatthebrainstemcellsdidpossessantigens,butunlesstherecipientwasprimedorpre-immunized,theantigenswerenotvisibletotheimmunesystemoftherecipientandnotrejected.
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5 I: A+ i/ o$ c( mUnderstandingtheimmunepropertiesofthesestemcellscouldhaveanenormouseffectonhowweperformbrainorretinaltransplantationsinthefuture.Stemcellsalreadyhavetheadvantageofbeingabletotransformordifferentiateintovarioustypesofcellsandcanbereproducedendlesslyoutsidethebody.Nowweknowthatatleastbrainstemcellsareimmuneprivilegedandcanbeusedwithoutthesameworryabouttissuematchingorimmunosuppressionthatistrueforothertypesoftissue.YoungisthedirectorofSchepensEyeResearchInstitute'sMindadeGunzburgRetinalTransplantationResearchCenter.Thecenteriscommitted,withafocusonretinalregeneration,tounlockingthemysteriesofvisionandfindingthecuresforblindingeyediseasesthatdevastatemillionsintheUnitedStatesandaroundtheworld.3 Q: M" ?; d+ i2 H% [! N# i

9 o. o, {& |  I& gThestudy,titledNeuralprogenitorcellslackimmunogenicityandresistdestructionasallograftscanbeobtainedattheStemsCellswebsiteathttp://stemcells.alphamedpress.org/,orbyemailingpattijacobs@hotmail.comormikey@vision.eri.harvard.edu.
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OthermembersoftheresearchteamincludeJunkoHori,TatFongNg,MarieShatos,andJ.WayneStreileinofSchepensEyeResearchInstituteofBostonandHenryKlassenoftheStemCellResearchProgramatChildren'sHospitalofOrangeCountyinOrange,California., k' [8 o7 n  }% W  f3 Q5 v% Y) R
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. F' n# g6 K) S! b/ W) m8 SSchepensEyeResearchInstituteisanaffiliateofHarvardMedicalSchoolandisthelargestindependenteyeresearchinstituteintheworld.# q) f/ r5 p3 `3 }& q0 ]# F

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作者: 8 s, m( b) ~; L2 w
来源: Schepens Eye Research Institute
  h% W0 N) Q# |$ O; ]% O发布者: 亦云