Tim hieu te bao goc

8/14/2019 Tim hieu te bao goc

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TM HIU V T BO GCLm Trn Mnh Hng C.SsR., S.T.D

(nguyn tc Anh ng, Dinhthaicx chuyn sang ting Vit)

DN NHP

T nhiu th k nay cc nh khoa hc bit rng mt s loi vt c th ti to cc bphn mt trn c th chng. Con ngi chng ta cng c chung c im ny,ging nh loi sao bin. Mc d c th chng ta khng th ti to c mt cng chnhay ngn tay b mt, nhng t bo mu, t bo da hay cc t bo khc vn thngxuyn c ti sinh trong c th ca chng ta. Nhng t bo ton nng gip chngta ti to m, ln u tin c pht hin trong qu trnh tin hnh th nghim vi tyxng, vo nhng nm 1950 dn n pht hin v s tn ti ca T BO GC (1)trong c th; t pht trin k thut cy ghp ty xng hin ang c ng dngrng ri trong y hc. Khm ph v t bo gc thp sng hy vng v tim nng y hcca k thut ti sinh. Ln u tin trong lch s, cc bc s c th ti to m b hyhoi nh mt ngun cung cp mi m nhng t bo khe mnh bng cch p dng kh

nng c nht v nh ca t bo gc nhm to ra nhiu loi t bo khc bit trong cth.

Khi cc nh khoa hc nhn ra c tim nng y hc ca k thut ti to thng quathnh tu cy ghp ty xng, h tip tc qu trnh tm kim nhng t bo tng ttrong phi. Nhng nghin cu ban u v qu trnh pht trin ca con ngi chngminh c rng t bo ca phi c kh nng sn sinh ra mi loi t bo trong c th.

How it works from Embryo to Stem cell :Cch thc to t bo gc t phi(1) Embryo : Phi - Trng c th tinh hoc nhn bn v tnh to phi. Phibt u phn chia.(2) 1 To 5 Days : 1 n 5 NgyPhi phn chia nhiu ln v c dng khi cu c gi l phi nang/phi bo.


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(3) 5 To 7 Days : 5 n 7 NgyVo thi im ny, t bo gc phi c th quan st c v c kh nng phttrin thnh bt k loi t bo no ca c th.(4) Stem Line : Dng T Bo GcT bo gc c tch ra v pht trin trong a nui cy. Khi chng phn chia

chng to ra dng t bo gc.(5) Tissue Production : Sn Xut T Bop dng nhiu cng thc dinh dng phi hp vi cc yu t khc nhau, cc nhkhoa hc hy vng c th bin i t bo gc thnh hn 200 loi t bo khc ca cth nh:Pancreatic Islet Cells : T Bo Ty Tng - C th s dng iu tr tiu ngMuscle Cells : T Bo C - C th dng khi phc hoc thay th tim b tnthngNerve Cells : T Bo Thn Kinh - C th c ng dng trong iu tr chng mttr v bnh Parkinson cng nh iu tr chn thng ct sng.

T nhng nm 1980, cc nh khoa hc tch chit thnh cng t bo gc phi cachut. Nhng ch n nm 1998, mt nhm cc nh khoa hc thuc i hcWinsconsin ti Madison di s ch o ca gio s James Thomson ln u tin thnh cng tch bit t bo gc phi ngi. H bit h tch c t bo gc, l vnhng t bo khng bit ha trong khong thi gian di; chng cng vn ginguyn kh nng c th bin i thnh nhiu loi t bo chuyn bit trong c t boc, t bo rut, t bo thn kinh v t bo sn.

Nh sinh hc kim gio s ngnh gii phu hc, Prof. James Thomson ngnglm vic vi chic laptop computer trong vn phng ti i hc Wisconsin Madison. ng ch o nhm nghin cu v tuyn b tch thnh cng dng tbo phi ca mt loi ng vt linh trng vo nm 1995. Khi u ny emn thnh tu ln u tin tch c dng t bo gc phi ngi vo nm 1998.


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The Promise of Stem Cell Research :Trin vng ca nghin cu t bo gcDrug Development and Toxicity Tests :Nghin cu dc phm v xt nghim c tnhExperiments to Study Development and Gene Control :

Th nghim nhm pht trin nghin cu v kim sot genCultured Pluripotent Stem Cells :T bo gc ton nng ang c nui dngTissues/Cells for Therapy : T bo ng dng trong iu trBone marrow : Ty xngNerve Cells : T bo thn kinhHeart Muscle Cells : T bo c timPancreatic Islet Cells : T bo ty tng

V th l nghin cu t bo gc c nhiu nh khoa hc eo ui vi hy vng tc nhng bc t ph ln trong y hc. H lun n lc tm ti nhng liu php

khi phc hoc thay th cc t bo tn thng nh nhng t bo to ra t t bo gc;ng thi mang hy vng n cho nhng ngi ang phi chu ng cn bnh ung th,tiu ng, cc bnh tim mch, chn thng ct sng cng nh cc chng ri lonkhc. C t bo gc phi v t bo gc trng thnh u l nhng c s cc nhkhoa hc pht trin nhng phng thc mi, c gi tr nhm sn xut dc phm vxt nghim.

The Promise of Stem Cell Research :Trin vng ca nghin cu t bo gcCultured Pluripotent Stem Cells :T bo gc ton nng ang c nui dngIdentify drug targets and test protential therapeutics :Xc nh mc tiu dc phm v th nghim tim nng liu php iu trToxicity Testing : Xt nghim c tnhStudy Cell differentiation : Nghin cu qu trnh bit ha ca t bo


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giai on pht trin sm nht ca phi. Trong giai on ny, cng nh giai on phttrin sau , cc loi t bo gc hnh thnh nn t bo chuyn bit hay bit ha ri thc hin cc chc nng c th trong c th ngi; v d nh t bo da, t bo mu,t bo c v t bo thn kinh.

T bo gc c mt kh nng v song, l chng c th pht trin thnh nhiu loi tbo khc trong c th. ng vai tr l h thng sa li cho c th, v mt l thuyt,chng c th phn chia khng hn nh thay th cc t bo khc, v ng thi mbo s lng cc loi t bo trong c th, min l con ngi hay con vt cn sng. Khimt t bo gc phn chia, mi mt t bo mi va c kh nng tr thnh t bo gcva c th tr thnh mt loi t bo khc vi chc nng chuyn bit nh t bo c, tbo hng cu hay t bo no.

Cell Differentiation Qu trnh bit ha t bo

Skin cells of epidermis : T bo biu bNeuron of Brain : Nron trong noPigment Cell : T bo sc tEctoderm (External Layer): Ngoi b (lp ngoi)Sperm : Tinh trngEgg : TrngGerm Cells : Giao t


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Zygote : Hp tBlastocyst : Phi boGastrula : Phi dMesoderm (Middle Layer): Trung b (Lp gia)Cardiac Muscle : C tim

Skeletal Muscle Cells : T bo c xngTubule Cell of the Kdney : T bo ng trong thnRed Blood Cells : T bo hng cuSmooth Muscle (in Gut): T bo c trn (trong rut)Endoderm (Internal Layer): Ni b (lp trong cng)Lung Cell (Alveolar Cell): T bo phi (T bo ti phi)Thyroid Cell : T bo tuyn gipPancreatic Cell : T bo ty tng

QU TRNH PHN CHIA V BIT HA T BO

Tt c cc loi t bo gc, d bt ngun t u, cng u c 3 c tnh chung: chngc kh nng phn chia v t ti to trong khong thi gian di; chng khng b bitha; v chng c th pht trin thnh cc loi t bo chuyn bit. iu kin thchhp, t bo gc c th pht trin thnh cc m v c quan chuyn bit.

Nhng c tnh c nht v nh ny l yu t ha hn, khin t bo gc tr thnhngun cung cp t bo, nhm iu tr cc chng bnh nh chng mt tr nh, ung th,bnh Parkinson, tiu ng loi 1, chn thng ct sng, t qu, bng, bnh tim,vim khp xng mn tnh v vim khp dng thp. Ngy nay, cc m hay c quan bbnh, b hy hoi u c thay th t ngi hin tng. V c bn, s lng ngicn cy ghp vt xa s lng b phn thay th sn c. T bo gc chnh l nguntim nng cung cp cc t bo v m c th c ng dng trong iu tr nhiu cnbnh, do t bo gc c th t phc hi v to ra cc t bo chuyn bit.

Nh bi chnh c tnh ny ca t bo gc khin cc nh khoa hc say m nghin cuhu tm kim cc bin php iu tr y hc nhm thay th cc t bo b hy hoi hocthng tn.

II. NGHIN CU T BO GC

1. T bo gc bt ngun t u?


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1. Fertilization : S th tinh2. 8-Cell embryo : Phi gm c 8 t bo. Trong giai on pht trin ny, t bo gcphi c coi l t bo gc tng nng (Totipotent stem cells); mi t bo ny c timnng pht trin thnh mt con ngi.3. Blastocyst : Phi bo. Trong giai on pht trin ny, t bo gc phi c coi l tbo gc ton nng (Pluripotent stem cells); mi t bo ny c tim nng pht trinthnh bt k t bo no trong c th.4. Fetus : Bo thai. Trong giai on pht trin ny, t bo gc phi c coi l t bogc ton nng (Pluripotent stem cells); mi t bo ny c tim nng pht trin thnhbt k t bo no trong c th.5. T bo gc cng tm thy ni c th trng thnh. Chng duy tr v cha tr c th.Chng c nh v ti nhiu t bo trong c th. Cc t bo gc trng thnh c timnng nhn ly nhng tnh cht ring bit, hu c th to nn cc t bo c s lnghn nh trong cc m. Chng c coi nh l cc t bo gc a nng (Multipotentstem cells).

Tt c chng ta u khi u s sng t mt t bo duy nht, gi l hp t, hnh thnhsau qu trnh th tinh. Hp t phn chia to thnh hai t bo; mi mt t bo trong

li phn chia v c tip din nh vy. Chng my chc, khong 5 ngy sau khi thtinh, hp t c dng mt qu bng rng, vi khong 150 t bo c gi l phi bo(blastocyst). Phi bo thm ch cn nh hn mt ht ct, bao gm 2 nhm t bo:nguyn bo nui phi (trophoblast) v khi t bo ni ti trong phi bo. T bo gcphi l nhng t bo hnh thnh nn khi t bo ni ti (inner cell mass). Do t bogc phi c th hnh thnh, nn bt c loi t bo no trong c th ngi trng thnhnn n cn c coi l t bo gc ton nng (pluripotent stem cell).


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T bo gc cng c th tm thy mt s loi m nht nh ngi pht trin tondin, t tr em n ngi trng thnh, vi s lng rt t. V d, t bo gc tyxng (t bo gc mu) c trong ty ca xng, chng pht trin thnh tt c cc loit bo mu chuyn bit.

QU TRNH BIT HA T BO GC TY XNG

Liver : Gan

Brain : NoCNS stem cells : T bo gc CNSSkeletal muscle : C xngBone : XngBlood cell : T bo muBlood vessel : Mch muBone marrow stromal cell : t bo m ty xngEpithelial cell : T bo biu mNeuron : NronGlial cell : T bo thn kinh mFat cell : T bo m m

Cardiac muscle : C tim

T bo gc trng thnh c lp trnh cch c trng hnh thnh nn cc loi tbo khc nhau cho m ca chng. Nhng t bo ny c gi l t bo gc a nng(multipotent stem cells). Hin nay cc khoa hc gia vn cha xc nh c ht mi tbo gc trng thnh trong cc c quan quan trng ca c th. Mt s m nh no,mc d c t bo gc tn ti nhng chng li khng hot ng, do chng khng snsng phn ng vi t bo b chn thng hay tn hi. Hin thi cc nh khoa hc cng


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ang tm kim cch thc kch thch nhng t bo gc ang hin din chng phttrin v to ra ng loi t bo cn thit nhm thay th t bo b hy hoi.

T BO GC CNG C TH THU HOCH C T NHNG NGUNNH DY RN, NHAU THAI CA TR S SINH

Fig. 1: The Umbilical CordHnh 1: Dy rn

Fig. 1 : The Amniotic FluidHnh 2 : Nc i

Hnh 1 v 2: T bo gc cng c th thu hoch c t nhng ngun nh dy rn,dch i hay nhau thai ca tr s sinh.

y l ngun t bo gc c th tip cn c, so vi m no hay ty xng trngthnh. Mc d cc nh khoa hc c th to nhng t bo ny trn a nui cy nhngrt gii hn. Mi y, cc nh khoa hc khm ph s tn ti ca t bo gc trongrng sa ca tr em v nc i bao xung quanh thai nhi. Nhng t bo ny cng c thc tim nng hnh thnh nn nhiu loi t bo khc. Nghin cu tm hiu c imnhng t bo ny rt ha hn, nhng mi ch c thc hin giai on u.


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2. Cc loi t bo gc

Trong c th mi chng ta u c cha t bo gc, t nhng giai on pht trin utin cho n cui cuc i.

V c bn c 3 loi t bo gc: t bo gc tng nng, t bo gc ton nng v t bogc a nng.

Loi t bo gc M t V d

T bo gc tng nng

Mi t bo cth pht trinthnh mt c thmi

T bo phi giai on mi phttrin (t 1 n 3 ngy)

T bo gc ton nng

T bo c thhnh thnh nn

bt c loi tbo no trongc th (trn 200loi)

T bo gc phi tm thy phi bo(t 5 n 14 ngy)

T bo gc a nng

T bo cbit ha, nhngvn c th hnhthnh nn mts loi t bokhc

M bo thai, mu dy rn v t bogc trng thnh

Tt c cc t bo gc u c ch trong nghin cu y hc, nhng mi loi u c ctrin vng cng nh gii hn ring. T bo gc phi c hnh thnh t rt sm trongqu trnh pht trin ca con ngi, v d nh phi bo, c tim nng to ra tt c ccloi t bo ca c th. T bo gc trng thnh ch c trong nhng loi m nht nh ngi pht trin ton din, t tr em thnh ngi ln, ch gii hn to ra mt s loit bo chuyn bit nht nh m thi.

CC NGUN KHC BIT CA T BO GC


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Embryonic stem cells : T bo gc phiEarly human embryo at blastocyst stage :Phi ngi giai on phi boAdult stem cells : T bo gc trng thnhFrom bone marrow in this example : Ly t ty xngTotipotent cells : T bo gc tng nng

Pluripotent cells : T bo gc ton nngCultured stem cells : T bo gc c nui cyDifferent culture conditions : iu kin nui cy khc nhauDifferent types of differentiated cells :Cc loi t bo bit ha khc nhauLiver cells : T bo ganNerve cells : T bo thn kinhBlood cells : T bo mu

3. T BO GC PHI L G ?

T bo gc phi c th c to ra t qu trnh th tinh trong ng nghim (IVF). Tbo gc phi khi ngun t nhng t bo to nn khi t bo ni ti trong phi bo.T bo gc phi chut c kh nng to ra bt c loi t bo no trong c th di iukin thch hp. Do , t bo gc phi c coi l t bo ton nng, c kh nng phnchia khng hn nh cho n khi sinh trng v bit ha. T bo gc phn chia lintip trong mi trng nui cy m trong lng p, nhng cng lc duy tr kh nnghnh thnh nn loi t bo khc khi c t trong mi trng thch hp thc yqu trnh bit ha.


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Stem Cells From In Vitro Fertilization (IVF) :T bo gc ly t qu trnh th tinh trong ng nghimUnused, frozen embryo slated to be thrown away :

Phi khng s dng v ng lnh b sa thiPluripotent stem cells : T bo gc ton nngPancreactic (islet cells) : t bo ty tngHematopoietic (blood cells) : t bo muCardiomyocytes (heart cells) : t bo timNeurons (brain cells) : NronHepatocytes (liver cells) : t bo gan

Cc mu t bo gc phi ngi hin ang c nghin cu. Mt vi nhm nghin cuang tm hiu liu t bo gc phi ngi c s hu cng nhng c tnh ging t bogc phi chut hay khng. Do t bo gc phi ngi ch mi c tch trong thi giangn y, do vn hiu bit ca chng ta cn hn ch v cch thc phn chia ni tbo gc. Tin hnh nghin cu trn h thng c th con ngi cng kh khn hn sovi chut. Tuy nhin, cc nh nghin cu v ang t c nhng tin b ng k,hu c th tm ra nhng liu php nhm thay th hoc khi phc cc m b hy hoi,trong vic s dng nhng t bo gc ny.

T bo gc phi ngi cn c th c thu hoch nh k thut chuyn nhn (nucleartransfer). K thut chuyn nhn t bo, t d t bo da cng l mt phng thc c


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tim nng to ra t bo gc phi.

How cloning might be used therapeutically : K thut nhn bn v tnh c ngdng trong iu tr bnh nh th no?

Anucleate unfertilized egg from donor :

Trng hin tng cha th tinh c tch nhnNucleus Transfer : Chuyn nhn t boAdult cell from patient : T bo trng thnh ca ngi bnh

loi vt, k thut chuyn nhn c thc hin bng cch ghp nhn ca t botrng thnh bit ha, v d t bo da chng hn, vo trng tch nhn. Trng c cha cht liu di truyn ca t bo da, sau c kch thch hnh thnh phibo, ri sau c th thu hoch t bo gc phi. Nhng t bo gc c to ra theocch ny l nhng bn sao hay phin bn v tnh ca t bo trng thnh ban u doADN (4) trong nhn ca chng ging vi ADN ca t bo trng thnh.

Cho n ma h nm 2006, k thut chuyn nhn vn cha thnh cng, nhm to tbo gc phi ngi, nhng cc tin b t c trn nghin cu ng vt cho ta hyvng rng cc khoa hc gia c th s dng k thut chuyn nhn ny trong vic to rat bo gc ngi trong tng lai.

3. T BO GC PHI L G ?

T bo gc trng thnh rt khc vi nhng t bo tch ra t phi hay bo thai v c cc m pht trin, v d nh loi vt hay ngi sau khi c sinh ra. C th tchnhng t bo ny t rt nhiu m hoc c quan, trong bao gm c no. Tuy nhinni ph bin nht c th thu hoch chng l t ty xng nm ngay chnh gia cc

ng xng.

Vic nghin cu v th nghim trn t bo gc trng thnh, gn y gy cnhiu s ch . Cc nh khoa hc pht hin s hin din ca t bo gc trng thnh nhiu m, so vi nhng g m h hiu bit trc y. V d, t bo gc mu thngthng ch sn xut cc loi t bo mu khc nhau. Tuy nhin nghin cu gn y licho thy mt s t bo gc trng thnh c th d dng thch nghi hn so vi cc quannim trc y. T bo gc trng thnh tch t chut (trng thnh) c th pht trin


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thnh t bo da, c v gan. Pht hin ny khin cc nh khoa hc t ra cu hi liu tbo gc trng thnh c th c s dng cy ghp hay khng. Mc d kt quvn cha c chng minh cng nh cha c thc hin vi t bo ngi. Tuynhin, cc nh khoa hc vn ang n lc tm kim mt phng php kch thch t bogc trng thnh, hay thm ch l nhng loi t bo trng thnh khc, chng tr

nn linh hot hn. Nu thnh cng, phng php s cung cp thm mt ngun t bogc cha bit ha.

Hn na, gn y mt gi thuyt v s bit ha t bo gc a ra lun im rng,mt s t bo gc trng thnh c th c tim nng to ra cc loi t bo khc, nhiuhn nhng g mi ngi vn ngh trc y. iu ny c ngha l t bo gc trong tyxng, ban u c cho l nhng t bo ch to ra mu, c th gp phn vo vic tisinh v s h hi ca gan, thn, tim, phi v cc c quan b hy hoi khc. Nu c thkim sot qu trnh bit ha ca t bo gc trng thnh trong phng th nghim,nhng t bo ny c th tr thnh nn tng cho nhng liu php iu tr nhiu cnbnh nan y.

Trong nhng nm va qua, vic nghin cu trong lnh vc t bo gc trng thnh pht trin vt bc. T bo gc trng thnh c th c phc hi bi cc m ly tbnh nhn, nui dng trong cc da cy v kch thch pht trin thnh nhiu loi tbo trng thnh. Vic s dng t bo gc cho phng php tr liu, thay v dng tbo gc phi, c nhiu thun li v mang mt ngha quan trng i vi lnh vckhoa hc, lun l v chnh tri.

To t bo gc t chnh m ca bnh nhn c th loi b hon ton vn h thngmin nhim (min dch) khng chp nhn.

1. T bo da c ly t phn bng ca bn nhn. Nhn c cha DNA (cu t c bndi truyn) ca ngi bnh c ly t t bo da.2. Nhn ca t bo ngi bnh c cy vo t bo trng cha th tinh, sau khi nhnca trng c tch ra khi3. T bo trng sinh sn (theo cp s nhn bi) v to nn cc t bo gc.4. Cc t bo gc c chuyn sang mt da nui cy chng c th pht trin thnhnhng loi t bo m bnh nhn cn cha tr cn bnh ca ng ta, t d nh gan,thn kinh, tim, t bo insulin.


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5. Cc t bo c tim vo cho bnh nhn, hu iu tr cn bnh cho bnh nhn. Cth ngi bnh s khng o thi cc t bo ny, bi v chng cha DNA ca ng ta(ngha l cc t bo u c chung mt loi DNA ging nhau, l h thng mindch s chp nhn).

T bo gc trng thnh khng gy ra khi u c qui (teratomas).ng dng t bo gctrng thnh trong iu tr gp phi rt t nhng vn v lun l v cng hon tontrnh c nhng tranh lun nng bng v chnh tr, lin quan n vic s dng phingi. (5)

Mc d lnh vc ny c bit hp dn, nhng n cng gy nhiu tranh ci trong cngng khoa hc v ng thi cn c thm nhiu nghin cu b sung k lng hiuc ton b tim nng ca t bo gc trng thnh, c bit l so vi t bo gcphi.

Trong bi vit k tip, tc ga s cp n tim nng s dng t bo gc bao gm

t bo gc phi v t bo gc trng thnh trong y khoa tr liu. ng thi cng nuln mt s vn nn v mt lun l, nu chng ta chp nhn cho cc khoa hc gia cphp s dng cc phi thng d hoc to nn cc phi mi bng phng php nhnbn v tnh v s dng cc phi y nh l nguyn liu sng, hon ton cho mc chnghin cu.

Hon chnh bn dch Lm Nguyen Dinh ThaiCopyright 2008 by Nguyen Dinh Thai

Ch thch :(1) Thut ng t bo gc ch tt c nhng t bo cha bit ha c kh nng phnchia thnh bt c loi t bo no. T bo gc sn sinh ra mt cp t bo con (daughtercells), trong mt t bo s pht trin bit ha, t bo cn li pht trin thnh tbo gc mi thay th t bo gc ban u. Thut ng gc ch ra rng nhng t bony l ngun gc ca cc t bo chuyn bit khc. Trong c th c rt nhiu t bogc cc giai on pht trin khc nhau. V d, tt c cc t bo no u c to rat mt nhm t bo thn kinh gc. Mi mt t bo thn kinh gc li sinh ra mt t bono v mt bn sao ca chnh n trong mi ln phn chia. Nhng t bo gc u tinl nhng t bo c sinh ra trong ln phn chia th nht ca trng th tinh cgi l t bo gc phi, nhm phn bit chng vi cc nhm t bo hnh thnh sau cc m c th (nh t bo thn kinh gc). Nhng t bo gc phi (trong giai on utin) pht trin thnh tt c cc loi m trong c th, v th chng c t cho ci tnt bo ton nng c th to ra mi loi t bo.(2) Totipotent Stem Cells: T bo gc tng nng. Loi t bo ny pht trin sau khitrng c th tinh khong 3-4 ngy, chng hin din phi du (morula). Nu ccchuyn gia tch mt trong cc t bo ny v cy vo t cung ca ngi ph n thnhcng. T bo tng nng ny s pht trin thnh mt thai nhi.(3) Pluripotent Stem Cells: T bo gc ton nng. Chng ch c kh nng pht trin


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thnh bt k t bo no trong c th, gm cc t bo c cc chc nng chuyn bit.Tuy nhin, chng khng c kh nng pht trin thnh mt hu th nh l t bogc tng nng (Totipotent Stem Cells).(4) ADN vit tt ca cm t - Acid Deoxyribonucleic. The genetic material found inall living things; contains the inherited characteristics of every living organism Cu

t c bn di truyn.(5) Xem Maureen L. Condic, The Basics About Stem Cells, First Things (January2002).http://www.firstthings.com/article.php3?id_article=1959

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