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日期: 2002-11-20 今日/总浏览: 1/6537 O; l, `/ E& G) A. y2 B' H M: }8 p
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) }/ N6 w8 i- |& pEmbryonicstemcellswereturnedintoinsulin-makingtissuethatwasabletokeepdiabeticmicealiveinanexperimentthatexpertssayisanimportantsteptowardanewtreatmentfordiabetes.
0 l. r& N( u5 g: C$ \: i% o9 U7 g8 `Researcherscautionedthatthetechniquewasnotyetreadyfortestinginhumans,butsaiditcouldleadeventuallytousingembryonicstemcellstomakenewinsulin-producingislets.TheisletsofLangerhansaregroupsofcellsinthepancreas,includingthebetacellsthatproduceinsulin.
- Q2 V' e! h" X* s' N0 {InastudyappearingthisweekintheProceedingsoftheNationalAcademyofSciences,StanfordUniversityresearcherssaytheyculturedmouseembryonicstemcellsuntiltheydevelopedintoatissuethatmadeinsulin.Aftertheyputthetissueintodiabeticmice,theanimalsweresustainedbytheinsulinproducedbythetissuegraft.
$ q( ]% g6 G0 j; a8 B- I9 FWe'vemadesomethingthatsharesseveralimportantpropertieswiththebetacells,butwehavenotmadebetacells,saidIngridC.Rulifson,afirstauthorofthestudy.Webelievethisisthefurthestanyonehasgone(inmakinginsulin-producingcellsfromembryonicstemcells).Thefactthatwewereabletoachieverescuesurvivalinthesemicehasn'tbeendemonstratedbeforeinthisway.
6 C2 L) \; z4 a, E. VDr.RobertGoldstein,chiefscientificofficerfortheJuvenileDiabetesResearchFoundationInternational,saidtheStanfordfindingisasignificantadvanceindiabetesresearchusingembryonicstemcells,buthesaiditwillhavenoimmediatehumanapplication.
. E& z" Q8 i5 E+ {. b" j# d; b: ^Theprincipleofbeingabletotakeembryonicstemcellsandreversediabetesisanextremelyimportantobservation,saidGoldstein.Hesaidresearchersultimatelyhopetouseembryonicstemcellstomakenewbetacellsthatcouldbetransplantedintodiabeticsandproducenormallevelsofinsulin.
0 H, W3 Y+ E0 p) b& c4 ~% o. L( THecalledtheStanfordstudyoneofthenecessarystepstowardachievingthisgoal,butemphasizedthatthenextsteps—translatingthemousedataintohumantherapy—couldtakemanyyears.
4 r. a" v5 |( B# O5 b5 l1 ZWecan'tfixpeopletomorrow,saidGoldstein.
- J7 v' _$ P4 [7 T4 M, V1 zEmbryonicstemcellsaretheancestralcellsfromwhichallthetissueinthebodydevelops.Scientistsbelievethatiftheycanlearnhowtodirectthetransformationofembryonicstemcellstheywillbeabletogrowfreshcellstoreplacethosethathavediedorstoppedfunctioning.
$ z8 G7 {5 {' a) U0 [/ K- C4 WSomeformsofdiabetesarecausedbythedeathormalfunctioningofthebetacellsthatmakeinsulin,ahormoneessentialforregulatingsugarintheblood.Researchershopetousehumanembryonicstemcellstogrownewbetacells,whichcouldthenbegraftedintodiabeticpatientstonormalizethemetabolismofsugar.
2 z* \( a2 K4 IIntheStanfordstudy,researchersusedspecialchemicalstocausemouseembryonicstemcellstotransformintocellmassesthatresembledpancreaticislets.Test-tubeexperimentsshowedthatthecellsmadeinsulin.$ _- y; b- b8 e( Y# H2 k/ \/ L
Theresearchersthenusedchemicalstokillthebetacellsinagroupoflaboratorymice,turningthemiceintodiabetics.Thescientiststhengraftedsomeoftheinsulin-producingtissueintotheanimals.Thetransplantedtissuemadeinsulin,respondingtothelevelsofsugarinthebloodstreamofthemice,andkeptthemicealive.
$ x& w% V6 `5 D- C8 A* G' [Controlmice,whichhaddiabetesbutdidnotreceivethegraft,died.
5 E" o. g# ^2 \; E. rToprovethatitwasthetransplantedtissuethatwasmakingtheinsulin,theresearchersremovedthegraftsafterthreeweeks.Themicesoondiedfromexcesssugarintheblood.) T: @) w; H* ~; h9 h& |- R
Atleastforashortperiod,weextendedthelifeoftheseanimalsconvincinglyandshowedthatuponremovalofthegrafttheanimalssufferedsevererelapseofthedisease,saidSeungK.Kim,aStanfordresearcherandseniorauthorofthestudy.
( A: Q/ d# v( W9 U8 EKimsaidthatthetransplantedtissueproducedinsulinatonly10percentto12percentofthelevelsinnormalmiceanddidnotproducesomeoftheotherhormonesorfactorsmadebythenormalbetacell.
$ E% O4 |- G! W, Q8 `Thisisonestepintherightdirection,saidKim.Headdedthatwehavealongwaytogobeforehumandiabeticscanbetreatedwithtissuefromembryonicstemcells.: q! f8 X" A7 B, S& v
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' ]$ c$ Y; H7 `5 m" S) g$ ^9 V3 oOntheNet:
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9 f: D4 r8 O7 E. iProceedingsoftheNationalAcademyofSciences:http://www.pnas.org/# b* r6 B5 B! }# ?/ r& e( c
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JuvenileDiabetesFoundationInternational:http://www.jdrf.org
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作者: PAUL RECER3 h3 H% m$ p e) N- i3 r
来源: AP Science% l: M1 \/ e4 `) n
发布者: 刘斌 |
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发表于 2008-12-30 23:17
