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Induction of Pluripotency:
; A) o( r: @! J2 K$ H& sFrom Mouse to Human7 Z9 [4 E1 I$ r. f% n- r$ i
Holm Zaehres1
( ?! D# D+ ^$ b5 C, l* i. h' \ and Hans R. Schöler1,
3 @( }) F; g6 T6 f*
6 a- c O7 r/ g* l1- w" m* y, D7 [3 g
Max Planck Institute for Molecular Biomedicine, Department of Cell and Developmental Biology, Münster, NRW 48149, Germany
1 P- d6 {7 f0 G8 @*Correspondence: schoeler@mpi-muenster.mpg.de
8 p* [2 \* @# m" X" UDOI 10.1016/j.cell.2007.11.020
" w! @7 E1 }3 ]+ t% j6 n- qIn this issue of Cell, Takahashi et al. (2007) transfer their seminal work on somatic cell - D$ B7 _% R& d T
reprogramming from the mouse to human. By overexpressing the transcription factor * v; d, \3 l' s3 v& N
quartet of Oct4, Sox2, Klf4, and c-Myc in adult human fbroblasts, they successfully * d4 v; E) W% r4 M- Z7 f) h2 J
isolate human pluripotent stem cells that resemble human embryonic stem cells by all
5 N( ]4 I. C! U6 ^3 ymeasured criteria. This is a signifcant turning point in nuclear reprogramming research
1 m3 \9 a! u8 s7 N7 `; Owith broad implications for generating patient-specifc pluripotent stem cells for research / G4 o! F8 m# N7 Z
and therapeutic applications.
# ^* ~ I: x X( ] m) LThis year’s three Physiology or Medi-6 x. T. s. R' Q$ }! }
cine Nobel Laureates—Martin Evans,
( t& F" ?. \' n7 J3 j0 MMario Capecchi, and Oliver Smithies—
9 g6 I9 D/ }; S+ _5 b( c% Kwill be honored in Stockholm in 10 / Y2 l' v/ ?& ^1 |* \, [) I) y6 W) T
days time for their discovery of DNA 0 F! a8 M+ l% b2 k: J5 Q
recombination and the development
( S% }4 H9 n0 G# L. ~3 I' `of mouse embryonic stem (ES) cell
( I' r$ Y# V. P/ ]technology. It was Martin Evans who
, @5 P! g. h! tdiscovered how to make mouse ES ) W/ E; w/ X# ?8 U" F$ M
cells, enabling any genetic alteration
) Z4 @, z0 T; ]3 `; k0 Eto be transferred to the germline and
_8 D. b/ B/ rhence to the next generation (Evans
0 l& A: U7 ]' h6 C8 B5 j2 m' jand Kaufman, 1981; Martin, 1981).
' Y7 G5 |8 }8 N u. ^5 @Before this breakthrough, researchers
3 k; G$ e( \7 M; ostudied mouse embryonal carcinoma d4 U7 k: k7 o3 P7 m
cells derived from tumors, which O2 g( k3 E2 J- I" b
could form every mouse cell lineage
) J1 u- R: a& ?: [* Jexcept the germline. Combining DNA
/ b( W" u1 d1 {2 S: grecombination and mouse ES cell ( Y: B9 c( K( U
technology revolutionized an entire
* ]' u6 R' T& dfeld of research, forming the basis for
3 e$ ~) }4 o* d$ [studying and understanding the roles
Z! k7 H, O6 [1 wof numerous genes in embryonic
$ {! s- u, x( y1 h0 {development, adult physiology, dis-7 o5 `8 C" w$ d/ h& j) T
ease, and aging. To date, more than 7 z" P4 g _+ Z$ m! P
500 mouse models of human disor-
0 f e- W1 u- Z6 ]: I8 ]ders have been generated. Now, with
7 t( D: m# U" s+ }! m3 m q4 qthe study by Takahashi et al. (2007)
$ J( u% s* Y. D6 h8 {' I2 i- b% Upublished in this issue of Cell, another
& R# H4 G G1 L* w7 x% Rimportant revolution is taking place.7 H }9 D0 N$ \& [& u
Last summer, Takahashi and
2 ~+ O9 q3 n$ ]9 \6 b1 @Yamanaka (2006) stunned the scientifc 9 l, j6 h# G+ v+ p [9 W; E& y
community with their study showing 0 U" ~. c, A9 m# T
molecular reprogramming of mouse ' T( Q2 J* C! P) v* `
somatic cells into induced pluripotent + {5 |4 D) D" T6 _( U/ J; g
stem (iPS) cells using just four factors: g- t2 V- X5 u% i- ^
Oct4, Sox2, Klf4, and c-Myc. Their
1 B I, @- {3 U" d7 ~elegant but demanding approach of
O( \" G5 U& F2 r! l& ~$ V1 I( W* Z7 ~- v- Oscreening for a cocktail of factors that
[- X T, k# ]# \0 Xcould reprogram mouse fbroblasts
6 |* r0 C& q: E( I' [starting from 24 candidate genes paid
0 \1 P6 g# b5 W7 U* j+ Loff with their detailed description of iPS
2 X' z4 C5 A0 J- f* k; xcells, which are almost indistinguish-
& [2 R+ v& D/ L4 R }( vable from mouse ES cells. As with all
) u% m! }0 G) V; E* t0 [scientifc discoveries, these exciting " m' H$ q- ^# X, \1 E. i) N
fndings had to be reproduced. Sev-
% C j& I2 K. teral studies published this year not & }6 V6 ]6 F" [: ~* y4 N
only reproduced but also extended
/ F Q3 {& k" x+ `) hthe Takahashi and Yamanaka fndings & Z3 g+ K9 e+ L2 F
by demonstrating the pluripotency and 2 c7 B' d# w! v( y+ |
differentiation potential of mouse iPS
5 |" o* G p# |cells in rigorous developmental assays & N& u, m3 X8 j6 V. ^# v, `
(Maherali et al., 2007; Okita et al., 2007; ; G2 \+ N/ _ O& T
Wernig et al., 2007).) u9 J1 `& T: c! Y5 _
In their new study, Takahashi,
2 u* v3 U/ N# B0 RYamanaka, and their colleagues . M. C' P8 e F7 x2 n/ @* a0 A5 X
(Takahashi et al., 2007) now translate 9 `6 _, J1 e& S F4 K
their remarkable fndings from mouse 9 U- \: U8 Q" j" j4 M6 W3 d
to human (see Figure 1). They selected ) `# B7 Z' m. R
adult human dermal fbroblasts and
3 ~- v8 ^1 p* `& N+ M7 n3 S7 ntwo other human fbroblast popula-
7 f* @0 D! E& |5 c2 B9 N3 y/ Q6 ^/ |tions (from synovial tissue and neo-( J, u' ^( R2 F
natal foreskin) from different human
$ h( K2 d: J$ z" ]donors as their reprogramming target + h$ J3 y# F* h% Y+ D" ~
cell populations. They then trans-6 A( s* e* f" a) N' m# u
duced the human fbroblast cultures
5 f" ^8 ^6 m) E8 Ewith retroviral vectors carrying trans- y0 d' u2 X g' Z
genes for the human versions of Oct4, 8 b/ W" G: ]; f4 z. g* T
Sox2, Klf4, and c-Myc and cultured
( f" j! I9 j5 v' k' Ythe cells under human ES cell culture
& b, O |( [6 Sconditions. Thirty days after transduc-
9 j$ |; ]1 }; I. ?tion, the culture plates were covered 9 x% E o6 P: F! G4 C
with human ES cell-like iPS colonies * b9 H8 ?' R9 E# d$ j
(among other colonies), which could 1 s$ x# t b+ v2 z4 P
be further propagated and expanded.
8 K/ K2 r" e4 M; C2 r2 L- }The retroviral vectors enabled silenc-
7 }8 C6 a2 ]$ ^1 p& ~ing of all four transgenes after human
$ N- K1 i% S# k$ XiPS formation (as found in the mouse
6 _" V* G. E# M5 {3 y' p1 [& R! jsystem) indicating that the iPS cells 2 c3 s+ @2 f: T) H! O& l+ d
are fully reprogrammed and no longer
! ? g# Z {( g. `- w7 F* q5 o" fdepend on transgene expression.7 ?/ U, Z/ t% R/ _' l. Z' g: t
Unlike the mouse study, human
( L( a7 [2 b* kiPS cells were generated without any
( o1 j# p% n( [, z- p7 wgenetic selection procedures. Given ( z6 d2 V: e0 m: X9 h
the lower mitotic index of human ES
) @- x4 p3 Y1 q) w5 Dcells, it is not surprising that the gen-
& D7 b! i+ \, f; t, J Leration of human iPS cells takes nota-6 I& P$ K5 B$ [
bly longer than in the mouse system.
" F9 N% r3 g) l, Y8 l V# BThe authors subjected their human 2 A: e9 T" [0 n- E0 i
iPS cells to a panel of assays to com-
' H7 w7 X1 C+ c! d0 q; vpare them with human ES cells. These
: d& Q- a& M3 h; S e( T- G0 Aassays included morphological stud-
2 m. U* j3 _) Mies, surface-marker expression, epi-! F1 L0 B& E2 w& w" l! E! W
genetic status, formation of embryoid ) T( M$ V$ x% J
bodies in vitro, directed differentia-
~* f- g% @; q- y+ y' z8 otion into neural cells and beating car-8 G* B; C. d: I" |# f
diomyocytes (according to human
8 m' @/ @' Q& ?4 Q. S8 y/ P+ Z$ ?ES cell differentiation protocols), and
3 M2 K' C% m3 R& Dfnally teratoma formation in vivo.
' a3 `! k- z+ ~- X9 T; E7 }1 `DNA microarray analysis revealed - T& P2 Y& |1 \9 x: l
the remarkable degree of similar-
; B# A2 D, j; p: i' g# `1 j# Oity between the global gene expres-
# t' O0 \+ `& T! q* tsion patterns of human iPS cells and
$ {0 e" {' Q! q# o; khuman ES cells. Notably, genomic ' e& K# w# X8 ^2 S8 B4 O) d
DNA analysis as well as analysis of
) O0 W# {+ j+ X' }short tandem repeats demonstrated 4 w4 i: C7 I8 S& h1 L) e
the genetic origin of independent
# y8 h$ q# |; N( f0 X8 k- Shuman iPS clones from their parental $ w, A% b+ r# U k; X& g
fbroblast populations.
+ v+ m( T) K3 J& |The derivation of mouse and then
) {7 c5 ]% Z- S3 P& C8 u( L3 z. C: Qhuman ES cells (Thomson et al., 1998) : }8 J |* Y& O( O: @6 }
as the gold standard of pluripotent # T9 h9 J, ^! N
stem cell populations has necessarily ) Z( |9 C% i: I4 R
led to emphasis on differences in the
6 t. T6 c* z8 H, v: N6 Y, g. h: Zregulation of self-renewal between
9 r; @4 y. C$ C5 c* imouse and human ES cells. For
; k7 c+ _* K. F- J4 ~7 ?9 ^example, human ES cells depend on 3 Y1 c: m/ ~ Y; a' K7 a
bFGF for self-renewal, whereas their
) w; @9 y. w3 @* ?mouse counterparts depend on the
4 h* Q' D& \) m$ ?Lif/Stat3 pathway; BMP is involved in
* M. N' ? a" [; ~' `& R& mmouse ES cell self-renewal, whereas
; L. i! i# w9 nin human ES cells it induces differen-. ^3 V2 P3 [$ J7 g' v( H5 x
tiation. Extrinsic factors and signals ( C' w( X& w$ @7 |, A' _
for maintaining pluripotency may dif-% s' y5 x# k3 C+ S! [
fer between mouse and human. How-
' V9 `0 n3 m8 x2 T; ]0 @$ H5 T8 Q; Lever, the ability to translate somatic
, V4 t; `6 x) n! X3 Ncell reprogramming from mouse to
: K' l8 j5 ~0 j$ u3 @% i% Ahuman using the same transcription
: J' b9 l3 c) L" j4 o9 Zfactor quartet further emphasizes the ' t) Z" K3 ^# P/ c# b4 _; A
conserved nature of the Oct4/Sox2 & d( M1 M6 I/ A8 k
transcription factor network that 6 ?7 y/ m/ s- }% @3 t9 |, X* F6 |
controls self-renewal of mouse and
; }3 D( D s9 ahuman ES cells (Boyer et al., 2005). % }. _$ @6 E8 w3 v. y+ y, Z
Given that Klf4 and c-Myc are chro-
1 |8 _0 S" O3 P. l$ ]7 [matin modifers and can immortal-
$ \" Y3 Z7 V& C/ r, R9 K/ G- nize cells, one might be able to fnd
: z" X7 P2 ]9 t/ |. zother factors or small molecules that / h4 J$ Y4 _/ \
could replace these two factors in the
5 T& C9 I& E1 ?$ c" y* [cocktail (Yamanaka, 2007). In these
. E1 j* M6 a. i" e9 g: fstudies, the possibility of retroviral 5 d. M7 G) E7 \( j
insertional mutagenesis, resulting 4 {8 t0 z, h7 j+ B! _
in the activation of other genes con-5 p/ y% }0 G. ?* G
tributing to reprogramming, cannot " l' [2 Q0 G$ ^$ J& A l& |
be excluded, providing an opportu-
! b6 g% Q0 ]% b+ y: x7 pnity to potentially identify new repro-
# j9 r" ~9 S! t7 t4 t1 S" Y2 jgramming factors beyond the cur-
& D4 S8 t O% o2 ~5 Lrent quartet. Also, taking a broader 6 Q; _& v5 C; X- K& L5 E
screening approach for reprogram-
& u# T, ?; u% y, l; Z5 X# Yming human fbroblasts (as Takahashi
+ b: U" v% K$ k1 f# rand Yamanaka did for their mouse 1 [! M7 e/ z0 B) {2 y& y5 X: @
study) might yield other combinations L {/ w4 B% }# y! ?, B
of reprogramming factors.
( l, p7 s4 f" p1 UDirect reprogramming of somatic
. T, B6 O1 A2 R/ ncells to a pluripotent state, thus revers-
" [! r/ x1 M9 a! v& r! g/ ming the developmental arrow of time,
$ M' _0 M) F# O8 V; T* gis considered by some to be the “holy # G# ?3 u4 f1 y2 ?5 S& j o9 @
grail” of stem cell research. Once the . | U/ P! V; y4 x6 s& V
results in human cells are confrmed, " _ U. H! m' ?5 c4 O
these advances will enable the cre-
- I2 N& K- F6 E% fation of patient-specifc stem cell lines
0 S9 p" }0 \0 n& O0 z) hto study different disease mechanisms 8 f! `* T8 k% q4 H2 _
in the laboratory. Such cellular models
% B5 n9 c9 ] Q- U+ I% c$ Yalso have the potential to dramatically + ?# f2 F' {6 p; Q* |# i7 @
increase the effciency of drug discov-
3 Z. D: Z% p& @0 |0 ~1 mery and to provide valuable tools for ! Y! O6 f. |! W5 g" h
toxicology testing. Furthermore, this " j9 l$ A, z1 q
reprogramming system could make 3 o4 r& d! ?' Y8 j# b3 Q
the idea of customized patient-specifc
- ~6 b ~: ?4 [& Bscreening and therapy both possible
" i- A" C. _6 K5 }! V2 vand economically feasible. Finally, the
3 y* g+ t2 x, n% d, Qwork will have a powerful impact on
) L5 [4 e' C3 g& Mthe intense debate regarding the moral, 0 s3 z' k, |# r, h0 o% ] V7 z
religious, and political aspects of ES cell " `2 m% H# k, g, G0 e5 q
research. However, a big mistake now
4 [% v/ v4 M0 c) V, [would be to consider human ES cells
( C; j# |% V. gobsolete. There are still many hurdles 1 f+ r! J$ T7 A
to overcome before we ful ly understand 4 W5 q e) O3 H9 U5 Y$ M) H. k0 Z
pluripotency and before we have human
, Y7 F4 S$ k J- W2 C2 J5 w; BiPS cells in hand that are suitable for : L4 [' z+ M& o" q
therapeutic application. For example,
9 R# M* _+ g! v! e# |9 H& {0 Za signifcant proportion of mice derived ; ~- ?3 w# K8 c$ @
from mouse iPS cells develop tumors + B! h) P/ x. Z, z
due to reactivation of the c-Myc retro-
' m! j% }+ Q4 h6 ]: Ovirus (Okita et al., 2007) compared to 6 H1 z1 n5 }: I0 o' m" d! y
mice derived from ES cells, which are - ~) R+ J5 D0 V# X1 V7 y0 y
normal. The search is now on to fnd a & R! X" X8 j7 F/ C
way to reprogram somatic cells without # g4 I7 m! v) X, f
retroviruses and maybe even using a
: q. }5 e$ l* ~! g- A! O zcocktail of small molecules. Given this, " ?3 F1 Z- g9 P1 O* K9 L" u
it should be emphasized that human
+ G2 ^; @9 h8 `) V7 ]+ hES cell research is more important than
3 I( `9 R( b6 d# M5 ^ever for it will shed light on how iPS 1 `8 s4 f" d, M u4 ~. f
cells can best be maintained in their a4 B) [3 _+ r1 b6 u9 R* i
pluripotent state and how they can be + G- Q# H& w( b( g3 ~. R% q
induced to differentiate into the cell " j& J7 |' W, @
lineage of interest. The feld of nuclear ! r }, s+ q( m& a% k/ ~
reprogramming has come a long way
# Z. b6 _+ k$ ~from the initial nuclear transplantation : l0 t( p$ Q4 B& T3 r9 P. }
studies in frogs 50 years ago, to the 0 A; q% r) E9 o- C/ A: p8 f
birth of Dolly, the frst mammal cloned
$ T0 Y5 ~. |0 Yfrom adult somatic cells (Wilmut et al.,
0 X- {; F: F3 V S0 @9 n1997), to the fallout from the fabricated
( {( O% F: L* s$ Ghuman nuclear transfer experiments
; o' q# d5 B5 i p; pof several years ago, to the landmark 6 f- Z/ t; c- m+ K5 [& g' E9 i3 J0 m
studies of Takahashi, Yamanaka, and 7 U7 @+ z/ z0 l/ k$ }( a% J
their colleagues, frst in mice and now " E" `2 b, A7 d. {9 S* K, C
in humans.
4 \! @. j% j% b& G# E8 g" hReFeRences
8 ~1 W4 r7 J: e5 JBoyer, L.A., Lee, T.I., Cole, M.F., Johnstone,
3 k6 g# {& Y+ kS.E., Levine, S.S., Zucker, J.P., Guenther, / c: C8 E. C! m. r) u4 _
M.G., Kumar, R.M., Murray, H.L., Jenner, R.G., / k+ K* l. I7 {; s0 L4 M: G& I5 Q
et al. (2005). Cell 122, 947–956.8 x6 T7 o( f6 E. X0 ]9 l7 h* |3 V+ C
Evans, M.J., and Kaufman, M.H. (1981). Na-
- t! X9 a6 }0 j! l& ~& bture 292, 154–156.. |2 n' r$ G, V A2 i( G
Maherali, N., Sridharan, R., Xie, W., Utikal, J., P- h$ R" r# U# ]$ {+ N2 s
Eminli, S., Arnold, K., Stadtfeld, M., Yachenko, 8 }2 d( J0 H/ v9 n0 s( A
R., Tchieu, J., Jaenisch, R., et al. (2007). Cell - `1 J) s+ |0 Z( k/ J, ]; L2 n
Stem Cell 1, 55–70.4 w. b, C0 p2 ^# Q& E" A. }
Martin, G.R. (1981). Proc. Natl. Acad. Sci. USA & l4 G- U; Y) O- s2 K% l
78, 7634–7638.1 h0 N Z B2 m& [' c1 p7 K
Okita, K., Ichisaka, T., and Yamanaka, S. 7 }7 M' S* i8 n' U* |
(2007). Nature 448, 313–317.8 ~* R( n1 o7 k' w
Takahashi, K., and Yamanaka, S. (2006). Cell ' [: v+ m4 ^' J- `& D7 n! m3 s4 g
126, 663–676.- T2 ]: G8 Y) }7 Z1 Z& @
Takahashi, K., Tanabe, K., Ohnuki, M., Narita,
% c6 n+ B; t4 T% H0 pM., Ichisaka, T., Tomoda, K., and Yamanaka, S. . ]( E3 w4 u& V4 D. e
(2007). Cell, this issue.8 Z' S( F3 c0 }$ ?3 E: F; J
Thomson, J.A., Itskovitz-Eldor, J., Shapiro, K7 b7 ~+ c" w; X
S.S., Waknitz, M.A., Swiergiel, J.J., Marshall,
: R6 O5 l( a/ W/ b/ P) ?# E# vV.S., and Jones, J.M. (1998). Science 282, + n! M4 j$ U: u! ]! L: {( j4 S
1145–1147.( _, z8 c, a! L5 U1 T
Wernig, M., Meissner, A., Foreman, R., Bram-" P5 K$ ]2 b) B) H5 O
brink, T., Ku, M., Hochedlinger, K., Bernstein,
; w, z# q4 J: V/ \B.E., and Jaenisch, R. (2007). Nature 448,
$ o5 f: ?/ ?! p318–324.
& e! _) @2 e6 f( n* [. ?. M. pWilmut, I., Schnieke, A.E., McWhir, J., Kind,
' x7 w* U" ~+ AA.J., and Campbell, K.H. (1997). Nature 385,
3 O8 S/ }7 |! v1 `+ ]810–813.
8 n3 X2 [% \4 } mYamanaka, S. (2007). Cell Stem Cell 1, 39–49. |
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发表于 2009-4-28 21:35
发表于 2009-5-16 10:41
