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日期: 2002-11-20 今日/总浏览: 1/653
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7 N J- u5 p( q* wEmbryonicstemcellswereturnedintoinsulin-makingtissuethatwasabletokeepdiabeticmicealiveinanexperimentthatexpertssayisanimportantsteptowardanewtreatmentfordiabetes.
- G M2 A) o4 GResearcherscautionedthatthetechniquewasnotyetreadyfortestinginhumans,butsaiditcouldleadeventuallytousingembryonicstemcellstomakenewinsulin-producingislets.TheisletsofLangerhansaregroupsofcellsinthepancreas,includingthebetacellsthatproduceinsulin.
( B) E/ g+ \+ zInastudyappearingthisweekintheProceedingsoftheNationalAcademyofSciences,StanfordUniversityresearcherssaytheyculturedmouseembryonicstemcellsuntiltheydevelopedintoatissuethatmadeinsulin.Aftertheyputthetissueintodiabeticmice,theanimalsweresustainedbytheinsulinproducedbythetissuegraft.9 G5 I& G) c" U R$ u1 M, t
We'vemadesomethingthatsharesseveralimportantpropertieswiththebetacells,butwehavenotmadebetacells,saidIngridC.Rulifson,afirstauthorofthestudy.Webelievethisisthefurthestanyonehasgone(inmakinginsulin-producingcellsfromembryonicstemcells).Thefactthatwewereabletoachieverescuesurvivalinthesemicehasn'tbeendemonstratedbeforeinthisway.& m0 x7 ^5 h- p! s# O. k+ G5 j
Dr.RobertGoldstein,chiefscientificofficerfortheJuvenileDiabetesResearchFoundationInternational,saidtheStanfordfindingisasignificantadvanceindiabetesresearchusingembryonicstemcells,buthesaiditwillhavenoimmediatehumanapplication.! U4 |+ S! O+ J6 H: J
Theprincipleofbeingabletotakeembryonicstemcellsandreversediabetesisanextremelyimportantobservation,saidGoldstein.Hesaidresearchersultimatelyhopetouseembryonicstemcellstomakenewbetacellsthatcouldbetransplantedintodiabeticsandproducenormallevelsofinsulin.8 c+ e+ O) {1 m+ ?* P
HecalledtheStanfordstudyoneofthenecessarystepstowardachievingthisgoal,butemphasizedthatthenextsteps—translatingthemousedataintohumantherapy—couldtakemanyyears.3 U) C5 R3 J I7 x5 q; U# @( v# v! y
Wecan'tfixpeopletomorrow,saidGoldstein.
5 S& v# K! _1 s' c& t# R l0 K8 ?Embryonicstemcellsaretheancestralcellsfromwhichallthetissueinthebodydevelops.Scientistsbelievethatiftheycanlearnhowtodirectthetransformationofembryonicstemcellstheywillbeabletogrowfreshcellstoreplacethosethathavediedorstoppedfunctioning.2 d' C( {9 [& A" K4 c; i- N0 P
Someformsofdiabetesarecausedbythedeathormalfunctioningofthebetacellsthatmakeinsulin,ahormoneessentialforregulatingsugarintheblood.Researchershopetousehumanembryonicstemcellstogrownewbetacells,whichcouldthenbegraftedintodiabeticpatientstonormalizethemetabolismofsugar.( J. w* I! g3 x8 [4 D
IntheStanfordstudy,researchersusedspecialchemicalstocausemouseembryonicstemcellstotransformintocellmassesthatresembledpancreaticislets.Test-tubeexperimentsshowedthatthecellsmadeinsulin.
. _0 L s6 b4 VTheresearchersthenusedchemicalstokillthebetacellsinagroupoflaboratorymice,turningthemiceintodiabetics.Thescientiststhengraftedsomeoftheinsulin-producingtissueintotheanimals.Thetransplantedtissuemadeinsulin,respondingtothelevelsofsugarinthebloodstreamofthemice,andkeptthemicealive.
4 r' @+ q% C# U3 x. j# qControlmice,whichhaddiabetesbutdidnotreceivethegraft,died.
; |1 W6 q1 i1 U; E9 H4 WToprovethatitwasthetransplantedtissuethatwasmakingtheinsulin,theresearchersremovedthegraftsafterthreeweeks.Themicesoondiedfromexcesssugarintheblood.
5 B; ^& s) l3 w- ]- q; }Atleastforashortperiod,weextendedthelifeoftheseanimalsconvincinglyandshowedthatuponremovalofthegrafttheanimalssufferedsevererelapseofthedisease,saidSeungK.Kim,aStanfordresearcherandseniorauthorofthestudy.
D( Z" X1 d1 G% O& G! eKimsaidthatthetransplantedtissueproducedinsulinatonly10percentto12percentofthelevelsinnormalmiceanddidnotproducesomeoftheotherhormonesorfactorsmadebythenormalbetacell.
, _+ i+ Y# \- h# ZThisisonestepintherightdirection,saidKim.Headdedthatwehavealongwaytogobeforehumandiabeticscanbetreatedwithtissuefromembryonicstemcells.
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+ z7 b7 J+ J# W, o& O7 b# O6 _% C8 @OntheNet:
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+ `( z7 A; d- H4 |5 Y+ n4 tProceedingsoftheNationalAcademyofSciences:http://www.pnas.org/! W' o j% _+ p/ F
3 M$ a6 Q% k. @8 F7 H4 p: |JuvenileDiabetesFoundationInternational:http://www.jdrf.org4 Q0 w# W) W P/ [* U0 j
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作者: PAUL RECER! U* \, x8 x- L& {+ L
来源: AP Science
$ s0 ?% B; ~# ~8 _# M5 K P" |1 l发布者: 刘斌 |
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发表于 2008-12-30 23:17
