Download Mechanisms of neural specification from embryonic stem cells

Available online at www.sciencedirect.com
Mechanisms of neural specification from embryonic stem cells
Nicolas Gaspard and Pierre Vanderhaeghen
While embryonic stem (ES) cells have been used for several
years to generate specific populations of neural cells in a
translational perspective, they have also emerged as a
promising approach in developmental neurobiology, by
providing reductionist models of neural development. Here we
review recent work that indicates that ES-based models are not
only able to mimic normal brain development, but also provide
novel tools to dissect the relative contribution of intrinsic and
extrinsic mechanisms of neural specification. These have thus
not only revealed insights on early steps such as neural
induction and regional patterning, but also temporal
specification of distinct neuronal subtypes, as well as the later
acquisition of more complex features such as cytoarchitecture
and hodological properties.
tiation and neurodevelopmental diseases. While many
studies have reported directed differentiation of ES cells
into specific types of neurons (reviewed in [2,4–6]), they
could not always be easily related to normal in vivo
developmental mechanisms. However more and more
studies focus on the basic mechanisms taking place
during ES-derived neural specification and their
relevance to brain formation. Here we review some of
these recent findings that indicate that ES cell-based
neural development can not only mimic but also provide
novel insights in developmental neurobiology, from early
events such as neural induction, to regional and temporal
patterning, and even to later steps leading to the acquisition of complex cytoarchitecture and connectivity.
Address
Université Libre de Bruxelles (U.L.B.), IRIBHM (Institute for
Interdisciplinary Research), Campus Erasme, 808 route de Lennik,
B-1070 Brussels, Belgium
Neural induction and early regional patterning
Corresponding author: Vanderhaeghen, Pierre
([email protected])
Current Opinion in Neurobiology 2010, 20:37–43
This review comes from a themed issue on
Development
Edited by Francois Guillemot and Oliver Hobert
Available online 14th January 2010
0959-4388/$ – see front matter
# 2009 Elsevier Ltd. All rights reserved.
DOI 10.1016/j.conb.2009.12.001
Introduction
The mechanisms of brain development remain one of the
most challenging questions in neurobiology, mainly
because of the complexity of the process, from molecular,
to cellular, anatomical and hodological levels.
On the basis of their unique self-renewal and pluripotency properties [1], ES cells have long attracted attention
not only as a potential source of cells of defined identity
for the development of cell therapy and pharmaceutical
screens, but also more recently to provide reductionist
models of mammalian development [2]. Moreover, the
availability of ES cell lines derived from human embryos,
as well as the recent possibility to generate ES-like
induced pluripotent stem (iPS) cells through reprogramming of adult cells [3], now opens the possibility to
investigate the mechanisms of human neural differenwww.sciencedirect.com
The first decisive step of neural development, neural
induction, is commonly thought to result from a ‘default’
pathway of embryonic differentiation involving BMP
inhibitors secreted by organizer fields [7]. Positive induction involving FGF pathways are also likely to be
involved, and the exact contribution of each mechanism
remains controversial [8]. Besides most of the data accumulated so far were obtained in non-mammalian organisms, leaving open the question of the mechanisms of
neural induction in mammals, which have now started to
be addressed using ES cells. When mouse ES cells are
cultured as single cells in a minimal medium devoid of
any extrinsic cues, they start to express neural markers
within hours [9], providing striking support for the
default model. Besides, several studies using mouse or
human ES cells have shown that neural cell fate can be
potently induced by inhibition of BMP/TGF-b signalling
[10–13]. On the contrary, FGF signalling seems to be
required as well in the process, suggesting that FGF
extrinsic cues, acting in an autocrine fashion, act in
concert with BMP inhibition to promote induction and
survival of neural progenitors from ES cells [9,14,15].
Finally, an ES-based functional screen identified the Wnt
antagonist sFRP2 as a potent neural inducer, suggesting a
negative regulation of neural induction by Wnt signalling
[16]. This was recently confirmed in vivo [17], enabling
to propose a coherent model where FGF/IGF and Wnts
coordinately control neural induction, in particular
through the regulation of Smad1, a major effector of
BMP pathways [18] (Figure 1).
Classical views of neural induction also imply that
anterior neural fate constitutes a primitive identity in
the early vertebrate embryo [7,19,20]. Posterior identities
are then specified by signals located in more caudal parts
of the embryo, including Wnts, FGFs and retinoic acid,
Current Opinion in Neurobiology 2010, 20:37–43
38 Development
Figure 1
Neural induction and regional patterning in ES cell neurogenesis. (a) Schematic representation of the mechanisms of neural induction and early
patterning of the neural plate/tube. Neural induction is regulated by the coordinated actions of BMP, Wnt and FGF/IGF signalling pathways. The neural
plate, initially of anterior identity, is then subsequently patterned by extrinsic morphogens along the rostro-caudal and the dorso-ventral axes into
discrete domains. (b) ES cell neural induction and ES-derived neural progenitor specification follow the same cues as in vivo to give rise to well-defined
neuronal populations.
while forebrain structures retain their identity by escaping the action of some of these signals, through soluble
morphogen antagonists secreted by surrounding rostral
structures (Figure 1a). ES cell-based models have now
provided ample confirmation for this model (Figure 1b).
In most differentiation paradigms, neural progenitors
derived from ES cells initially express markers of rostral
neural identity [21,22,23] that can be converted to more
caudal fates, including spinal cord, midbrain and hindbrain, by retinoic acid or FGFs [12,23–30,31]. Moreover,
adding soluble inhibitors of Wnt signals during early ESderived neural induction enhances the proportion of
forebrain progenitors [29,32]. Similarly it was found that
when ES cells are cultured at low density in a medium
devoid of serum or any morphogen, but allowing cell
survival by insulin, they efficiently differentiate in forebrain-like progenitors, mainly of telencephalic identity,
including cortical progenitors [33]. Moreover, using a
Current Opinion in Neurobiology 2010, 20:37–43
differentiation medium completely devoid of any morphogen and without insulin, ES cells were found to
efficiently convert to neural cells displaying anterior
identity, corresponding to the rostral most part of the
neural plate [34]. These cells then further adopt a
pattern of neuronal differentiation that corresponds to
anterior hypothalamic structures, which correspond to the
derivatives of the most anterior and medial plate in vivo
[35].
Similarly, the general mechanisms of dorso-ventral neural
patterning are thought to be conserved throughout the
neural tube, where different concentrations of morphogens induce specific expression of transcription factors in
successive discrete domains, which confer to distinct
subpopulations of progenitors the competence to generate types of neurons and glial cells in a region-specific
manner [36,37]. Dorso-ventral patterning is similarly
www.sciencedirect.com
Mechanisms of neural specification from embryonic stem cells Gaspard and Vanderhaeghen 39
recapitulated when ES cell-derived committed progenitors of spinal cord, midbrain or forebrain are treated with
Sonic Hedgehog (Shh) or WNT/BMP morphogens, or
their inhibitors [20,21,24,26–29] (Figure 1b).
Figure 2
Collectively these data indicate that mouse and human
ES cells can undergo a primitive pattern of differentiation
linking neural induction with anterior neural specification, similar to non-mammalian species, which is then
refined by extrinsic cues to allow regional patterning
along both anterior–posterior and dorso-ventral axes
(Figure 1b).
Temporal patterning: intrinsic mechanisms of
ES cell neurogenesis
Temporal patterning plays a major role in neural development to enable cell diversification within each brain
region [38,39]. A first striking feature of this process is that
in most cases the generation of neurons precedes the
generation of glial cells, both in vitro and in vivo [40].
Taking advantage of an ES cell-based system that recapitulates this sequence in vitro [41] (Figure 2a), Naka et al.
performed a gene expression and RNAi screen that
allowed to identify the CoupTF transcription factors as
a key intrinsic factor controlling the gliogenic switch, in
particular through the regulation of the epigenetic silencing of glial genes [42]. In vivo experiments then confirmed this finding and unexpectedly unraveled the
implication of both genes in the temporal specification
of cortical neurons [42], thereby providing the first
evidence of evolutionary conservation of temporal patterning mechanisms. A similar model was also used
recently to uncover the crucial role of the CSL transcription factor acting downstream of Notch in the neuro-glial
switch [43].
Throughout the vertebrate nervous system, neural progenitors generate different types of neurons, and this
mechanism of sequential neurogenesis is at the core of
neuronal diversity, particularly in complex neural structures such as the cerebral cortex. A prominent characteristic of the development of cortical neurons is that laminar
fate and subtype specification are linked to neuron birthdate, as early-born neurons settle in deep layers whereas
late-born neurons populate the upper layers [44,45].
Cortical progenitors are thought to be at least partly
multipotent and to undergo a sequential shift in their
competence to generate different subtypes of neurons
and such properties are conserved when cortical progenitors are cultured in vitro [46].
Remarkably, similarly complex temporal patterns have
now been observed during ES-derived neural specification, in two recently described models of corticogenesis in
vitro [33,47]. Using independent approaches allowing
the efficient generation of ES-derived cortical progenitors, these cells were found to generate a wide diversity of
www.sciencedirect.com
Temporal patterning during ES cell neurogenesis. (a) In an ES-based
model of gliogenic transition, ES-derived neural progenitors switch from
a neurogenesis to gliogenesis in vitro. This switch is under the control of
the COUP-TFI/II transcription factors. (b) ES-derived cortical progenitors
undergo a sequential shift in competence and successively generate
different subtypes of neurons. (c) Neural rosette cells represent a
transient population of ES-derived neural progenitors able to self-renew
under the control of Shh and to respond to patterning cues. FGF2
treatment leads to their differentiation in FGF2/EGF-responsive tripotent
neural stem cells together with a loss of their anterior identity and
responsiveness to external cues.
Current Opinion in Neurobiology 2010, 20:37–43
40 Development
cortical neuronal types in vitro, from pioneer CajalRetzius neurons to deep and upper layer neurons
(Figure 2b). When examining the birth-date of these
various populations in combination with analysis of
layer-specific marker expression, it was found that the
different neuronal subtypes are generated sequentially,
following neurogenic waves that are remarkably similar to
those described in vivo [33,47]. Importantly this
temporal pattern is also conserved at the single progenitor
level, as shown by clonal analyses [33]: even when
cultured at clonal density, the single ES-derived cortical
progenitors can generate neurons of distinct layer identity, and their potential evolves with time, as early progenitors mainly generate deep layer neurons, while the
progeny of late progenitors is shifted to upper layer
neurons. The time-dependence of generation of neuronal
diversity was further confirmed by in vivo grafting experiments in neonatal cortex, which revealed that ESderived neurons grafted after various periods of differentiation displayed specific patterns of axonal projections,
corresponding to the layer identity that they acquired in
vitro [33]. Altogether, these data represent the first
demonstration that the complex events leading to the
generation of neurons displaying different layer-specific
patterns of identity can take place completely outside of
the developing brain and rely mainly on a cell populationintrinsic pathway. Importantly, whereas in vivo deep and
upper layer neurons each represent about half of the
Figure 3
Cytoarchitecture and hodological specification during ES cell neurogenesis. (a) Schematic representation of polarized laminar structures that develop
from ES-derived cortical progenitors in floating aggregates and are reminiscent of the cytoarchitecture of the developing cortex. (b–e) ES-derived
cortical neurons grafted in the neonatal motor cortex (c) send axonal projections indicating a visual identity (compare the schematic representations of
the projections from the graft (e) to the endogenous projections from layer VI (b) and V (c) neurons). PPN is pediculopontine nucleus; LG, MG, VB and
VL are lateral geniculate, medial geniculate, ventro-basal and ventro-lateral nuclei of the thalamus; CC is corpus callosum and LV is lateral ventricle.
Current Opinion in Neurobiology 2010, 20:37–43
www.sciencedirect.com
Mechanisms of neural specification from embryonic stem cells Gaspard and Vanderhaeghen 41
cortex, ES-derived pyramidal neurons are strongly
skewed towards a deep layer identity [33,47],
suggesting that other cues are missing in vitro, for instance
those associated with a vascular niche [48].
While these studies emphasize on intrinsic changes in
competence of ES-derived progenitors over time, other
studies have explored the possibility to generate selfrenewing neural stem cells from ES cells. Several protocols have been developed to support long-term expansion of ES-derived neural stem cells [21,49,50].
Although the possibility to keep partially committed
neural progenitors at hand for further differentiation is
appealing, one has to bear in mind that unlimited selfrenewal is not observed in neural precursors in vivo [40].
Indeed long-term self-renewal of neural precursors is
usually achieved with extracellular cues such as FGF-2
and EGF, which alter cellular identity and potential of
neural progenitors and stem cells [51,31,50]. In this
context, the so-called rosette neural stem cells, which
have been derived from ES cells as well as from early
neural plate cultures, are particularly intriguing
(Figure 3c) (reviewed in [52]). These cells seem to rely
primarily on Shh instead of FGFs for their self-renewal,
and display a primitive anterior neural plate identity that
can be patterned by extrinsic cues, at least at early stages
[18]. It will be interesting to assess further the fate and
competence of these cells in relation with their selfrenewal properties, as well as their in vivo relevance,
which would enable to test more directly the possibility
to generate a ‘pluripotent neural stem cell’, either ex vivo
or purely in vitro.
From stem cells to cytoarchitecture and
neuronal networks
Perhaps the most surprising lesson learned from recent
ES cell models is that at least some important components of complex features such as cytoarchitecture
and hodological properties can be specified in vitro.
When ES cells are cultured as bowls of cells differentiating into cortical-like progenitors [47], they develop into
neural structures that display a striking polarized cellular
organization, with neural progenitors occupying deeper
layers of the bowls, and neurons accumulating at their
periphery, following an organization highly reminiscent
of a nascent cortical primordium (Figure 3a). These data
constitute a first proof of principle that a brain-like
structure can emerge as a self-organizing cytoarchitecture
in vitro, which constitutes a promising system to decipher
some of the underlying mechanisms of brain patterning.
While in vitro systems of corticogenesis thus display
remarkable similarities with in vivo developmental processes, it should be noted however that the differentiation
taking place in vitro differs from in vivo corticogenesis in
several important aspects. Despite the fact that neurons
with all six layers identities are generated in vitro, they do
www.sciencedirect.com
not seem to be able to form a six-layered organization.
Interestingly, the ability to form a six-layered structure
following a typical inside-out pattern of migration is a
unique property of the neocortex, that is the part of the
cortex that is the most recent in evolution. This may
suggest that in vitro cortical neurogenesis may display
most similarities to a primitive pathway of corticogenesis
corresponding to a more ancestral form of cortex, characterized by a simpler pattern of layer generation, or that
additional extrinsic cues are required that are only present
in vivo.
In addition to layers, the cerebral cortex can be subdivided into different functional areas. The motor,
somatosensory, auditory, visual and limbic areas are
composed of neurons receiving and sending modalityspecific axonal projections that constitute a major landmark of areal identity (Figure 3b, c). Surprisingly, when
ES-derived cortical neurons are grafted into neonatal
cortex, they send axonal projections that indicate essentially a limbic or visual area identity, corresponding
mainly to the occipital (posterior) pole of the cortex
(Figure 3d, e). Importantly, these results were all
obtained with grafts in the frontal cortex, suggesting
that the patterns observed were not due to the respecification of the grafted neurons through the influence of the host. Confirming this hypothesis, ES-derived
cortical progenitors and neurons before grafting express
typical markers of the occipital cortex, such as
COUP-TFI/II transcription factors [33]. It remains to
be determined by which mechanism cortical progenitors
acquire such a specific areal identity. While the development of cortical areas is thought to occur through the
interplay of intrinsic and extrinsic mechanisms [53],
these data constitute the first and surprising demonstration of the acquisition of cortical areal identity without any influence from the rest of the brain. ES-derived
corticogenesis combined with in vivo grafting thus
enables to study crucial aspects of cortical areal patterning that have remained controversial so far because of
the complexity of the in vivo system.
Conclusions
ES cell systems have been long considered as promising
tools to generate specific types of neurons in vitro, but
they now emerge as a promising resource complementary
to in vivo approaches to study neural specification, including some of its most complex features. The relative
ease to manipulate ES cells genetically, either in functional screens or to label specific cell types, will provide
novel opportunities to uncover candidate genes involved
in most aspects of neural specification. It will be particularly exciting to implement these approaches to hES and
hiPS cells, to dissect the mechanisms of normal and
pathological neurodevelopment in the human species,
which remain one of the last frontiers of developmental
neurobiology.
Current Opinion in Neurobiology 2010, 20:37–43
42 Development
Acknowledgements
The work of the authors presented here was funded by the Belgian FNRS/
FRSM, the Queen Elizabeth Medical Foundation, the Simone et Pierre
Clerdent Foundation, the Action de Recherches Concertées (ARC)
Programs, the Interuniversity Attraction Poles Program (IUAP), the RW
Program CIBLES and the EU Marie-Curie Programme. P.V. is a Senior
Research Associate of the FNRS, N.G. was funded as a Research Fellow of
the FNRS. We apologize to colleagues whose work could not be mentioned
owing to space limitations.
References and recommended reading
Papers of particular interest, published within the annual period of
review, have been highlighted as:
of special interest
of outstanding interest
1.
Smith AG: Embryo-derived stem cells: of mice and men. Annu
Rev Cell Dev Biol 2001, 17:435-462.
2.
Murry CE, Keller G: Differentiation of embryonic stem cells to
clinically relevant populations: lessons from embryonic
development. Cell 2008, 132:661-680.
3.
Yamanaka S: Pluripotency and nuclear reprogramming. Philos
Trans R Soc Lond B Biol Sci 2008, 363:2079-2087.
4.
Gotz M, Barde YA: Radial glial cells defined and major
intermediates between embryonic stem cells and CNS
neurons. Neuron 2005, 46:369-372.
5.
Zhang SC, Li XJ, Johnson MA, Pankratz MT: Human embryonic
stem cells for brain repair? Philos Trans R Soc Lond B Biol Sci
2008, 363:87-99.
6.
Yeo GW, Coufal N, Aigner S, Winner B, Scolnick JA,
Marchetto MC, Muotri AR, Carson C, Gage FH: Multiple layers of
molecular controls modulate self-renewal and neuronal
lineage specification of embryonic stem cells. Hum Mol Genet
2008, 17:R67-R75.
7.
Levine AJ, Brivanlou AH: Proposal of a model of mammalian
neural induction. Dev Biol 2007, 308:247-256.
8.
Stern CD: Neural induction: 10 years on since the ‘default
model’. Curr Opin Cell Biol 2006, 18:692-697.
9.
Smukler SR, Runciman SB, Xu S, van der KD: Embryonic stem
cells assume a primitive neural stem cell fate in the absence of
extrinsic influences. J Cell Biol 2006, 172:79-90.
In this paper, the authors provide provocative support for the neural
default pathway, showing that ES cells cultured without any extrinsic cue
rapidly express markers of neural fate. They also explore the relationships
between the default pathway and FGF signalling.
10. Pera MF, Andrade J, Houssami S, Reubinoff B, Trounson A,
Stanley EG, Ward-van OD, Mummery C: Regulation of human
embryonic stem cell differentiation by BMP-2 and its
antagonist noggin. J Cell Sci 2004, 117:1269-1280.
11. Chambers SM, Fasano CA, Papapetrou EP, Tomishima M,
Sadelain M, Studer L: Highly efficient neural conversion of
human ES and iPS cells by dual inhibition of SMAD signaling.
Nat Biotechnol 2009, 27:275-280.
12. Kawasaki H, Mizuseki K, Nishikawa S, Kaneko S, Kuwana Y,
Nakanishi S, Nishikawa SI, Sasai Y: Induction of midbrain
dopaminergic neurons from ES cells by stromal cell-derived
inducing activity. Neuron 2000, 28:31-40.
13. Vallier L, Reynolds D, Pedersen RA: Nodal inhibits differentiation
of human embryonic stem cells along the neuroectodermal
default pathway. Dev Biol 2004, 275:403-421.
14. Ying QL, Stavridis M, Griffiths D, Li M, Smith A: Conversion of
embryonic stem cells into neuroectodermal precursors in
adherent monoculture. Nat Biotechnol 2003, 21:183-186.
15. Lavaute TM, Yoo YD, Pankratz MT, Weick JP, Gerstner JR,
Zhang SC: Regulation of neural specification from human
embryonic stem cells by BMP and FGF. Stem Cells 2009,
27:1741-1749.
Current Opinion in Neurobiology 2010, 20:37–43
16. Aubert J, Dunstan H, Chambers I, Smith A: Functional
gene screening in embryonic stem cells implicates Wnt
antagonism in neural differentiation. Nat Biotechnol 2002,
20:1240-1245.
This paper constitutes the first example of an ES-based screen that
identifies potential regulators of neural fate. The authors thereby identify a
Wnt inhibitor as a most promising candidate, providing indication that
Wnts are negative regulators of neural induction.
17. Fuentealba LC, Eivers E, Ikeda A, Hurtado C, Kuroda H, Pera EM,
De Robertis EM: Integrating patterning signals: Wnt/GSK3
regulates the duration of the BMP/Smad1 signal. Cell 2007,
131:980-993.
18. Pera EM, Ikeda A, Eivers E, De Robertis EM: Integration of IGF,
FGF, and anti-BMP signals via Smad1 phosphorylation in
neural induction. Genes Dev 2003, 17:3023-3028.
19. Wilson SW, Houart C: Early steps in the development of the
forebrain. Dev Cell 2004, 6:167-181.
20. Wilson SI, Edlund T: Neural induction: toward a unifying
mechanism. Nat Neurosci 2001, 4(Suppl.):1161-1168.
21. Elkabetz Y, Panagiotakos G, Al SG, Socci ND, Tabar V, Studer L:
Human ES cell-derived neural rosettes reveal a functionally
distinct early neural stem cell stage. Genes Dev 2008,
22:152-165.
The authors describe the properties of a seemingly novel type or stage of
neural stem cells, isolated primarily from human ES cells, the neural
rosette stem cells. They show that these cells display self-renewal
capacity, while retaining the ability to respond to extrinsic patterning
cues.
22. Li XJ, Du ZW, Zarnowska ED, Pankratz M, Hansen LO, Pearce RA,
Zhang SC: Specification of motoneurons from human
embryonic stem cells. Nat Biotechnol 2005, 23:215-221.
23. Wichterle H, Lieberam I, Porter JA, Jessell TM: Directed
differentiation of embryonic stem cells into motor neurons.
Cell 2002, 110:385-397.
24. Lee SH, Lumelsky N, Studer L, Auerbach JM, McKay RD: Efficient
generation of midbrain and hindbrain neurons from mouse
embryonic stem cells. Nat Biotechnol 2000, 18:675-679.
25. Salero E, Hatten ME: Differentiation of ES cells into cerebellar
neurons. Proc Natl Acad Sci U S A 2007, 104:2997-3002.
26. Su HL, Muguruma K, Matsuo-Takasaki M, Kengaku M,
Watanabe K, Sasai Y: Generation of cerebellar neuron
precursors from embryonic stem cells. Dev Biol 2006,
290:287-296.
27. Mizuseki K, Sakamoto T, Watanabe K, Muguruma K, Ikeya M,
Nishiyama A, Arakawa A, Suemori H, Nakatsuji N, Kawasaki H
et al.: Generation of neural crest-derived peripheral
neurons and floor plate cells from mouse and primate
embryonic stem cells. Proc Natl Acad Sci U S A 2003,
100:5828-5833.
28. Ikeda H, Osakada F, Watanabe K, Mizuseki K, Haraguchi T,
Miyoshi H, Kamiya D, Honda Y, Sasai N, Yoshimura N et al.:
Generation of Rx+/Pax6+ neural retinal precursors from
embryonic stem cells. Proc Natl Acad Sci U S A 2005,
102:11331-11336.
29. Watanabe K, Kamiya D, Nishiyama A, Katayama T, Nozaki S,
Kawasaki H, Watanabe Y, Mizuseki K, Sasai Y: Directed
differentiation of telencephalic precursors from embryonic
stem cells. Nat Neurosci 2005, 8:288-296.
30. Perrier AL, Tabar V, Barberi T, Rubio ME, Bruses J, Topf N,
Harrison NL, Studer L: Derivation of midbrain dopamine
neurons from human embryonic stem cells. Proc Natl Acad Sci
U S A 2004, 101:12543-12548.
31. Bouhon IA, Joannides A, Kato H, Chandran S, Allen ND:
Embryonic stem cell-derived neural progenitors display
temporal restriction to neural patterning. Stem Cells 2006,
24:1908-1913.
In this paper, the authors show that ES cell neural induction generates
progenitors with a primitive anterior identity, which can be patterned by
extrinsic cues to more caudal fates. Importantly this primitive identity and
competence are lost upon prolonged culture.
www.sciencedirect.com
Mechanisms of neural specification from embryonic stem cells Gaspard and Vanderhaeghen 43
32. Watanabe K, Ueno M, Kamiya D, Nishiyama A, Matsumura M,
Wataya T, Takahashi JB, Nishikawa S, Nishikawa S, Muguruma K,
Sasai Y: A ROCK inhibitor permits survival of dissociated
human embryonic stem cells. Nat Biotechnol 2007, 25:681-686.
33. Gaspard N, Bouschet T, Hourez R, Dimidschstein J, Naeije G, van
den AJ, Espuny-Camacho I, Herpoel A, Passante L,
Schiffmann SN et al.: An intrinsic mechanism of corticogenesis
from embryonic stem cells. Nature 2008, 455:351-357.
Together with [46] this is the first demonstration of efficient generation of
cortical neurons in vitro, following a precise temporal pattern similar to in
vivo. In addition the authors present evidence that even areal identity of
the cortical progenitors can be acquired without influence from the rest of
the brain.
34. Wataya T, Ando S, Muguruma K, Ikeda H, Watanabe K, Eiraku M,
Kawada M, Takahashi J, Hashimoto N, Sasai Y: Minimization of
exogenous signals in ES cell culture induces rostral
hypothalamic differentiation. Proc Natl Acad Sci U S A 2008,
105:11796-11801.
In this paper, the authors culture ES cells in a chemically defined minimal
medium devoid of any extrinsic cue to demonstrate the primitive acquisition of an anterior hypothalamic fate.
35. Inoue T, Nakamura S, Osumi N: Fate mapping of the mouse
prosencephalic neural plate. Dev Biol 2000, 219:373-383.
36. Wilson SW, Rubenstein JL: Induction and dorsoventral
patterning of the telencephalon. Neuron 2000, 28:641-651.
37. Jessell TM: Neuronal specification in the spinal cord: inductive
signals and transcriptional codes. Nat Rev Genet 2000, 1:20-29.
38. Okano H, Temple S: Cell types to order: temporal specification
of CNS stem cells. Curr Opin Neurobiol 2009.
39. Pearson BJ, Doe CQ: Specification of temporal identity in the
developing nervous system. Annu Rev Cell Dev Biol 2004,
20:619-647.
40. Anderson DJ: Stem cells and pattern formation in the nervous
system: the possible versus the actual. Neuron 2001, 30:19-35.
41. Okada Y, Matsumoto A, Shimazaki T, Enoki R, Koizumi A, Ishii S,
Itoyama Y, Sobue G, Okano H: Spatiotemporal recapitulation of
central nervous system development by murine embryonic
stem cell-derived neural stem/progenitor cells. Stem Cells
2008, 26:3086-3098.
42. Naka H, Nakamura S, Shimazaki T, Okano H: Requirement for
COUP-TFI and II in the temporal specification of neural stem
cells in CNS development. Nat Neurosci 2008.
In this paper, the authors use an ES-based system to identify CoupTFI/II
transcription factors as the first key intrinsic regulators of temporal
patterning in mammals.
43. Namihira M, Kohyama J, Semi K, Sanosaka T, Deneen B, Taga T,
Nakashima K: Committed neuronal precursors confer
www.sciencedirect.com
astrocytic potential on residual neural precursor cells. Dev Cell
2009, 16:245-255.
44. Molyneaux BJ, Arlotta P, Menezes JR, Macklis JD: Neuronal
subtype specification in the cerebral cortex. Nat Rev Neurosci
2007, 8:427-437.
45. Leone DP, Srinivasan K, Chen B, Alcamo E, McConnell SK: The
determination of projection neuron identity in the developing
cerebral cortex. Curr Opin Neurobiol 2008, 18:28-35.
46. Shen Q, Wang Y, Dimos JT, Fasano CA, Phoenix TN,
Lemischka IR, Ivanova NB, Stifani S, Morrisey EE, Temple S:
The timing of cortical neurogenesis is encoded within
lineages of individual progenitor cells. Nat Neurosci 2006,
9:743-751.
Using time lapse analysis of cortical progenitors cultured ex vivo, the
authors provide the first evidence that a complex temporal patterning of
generation of different neuronal subtypes can emerge in a purely in vitro
setting.
47. Eiraku M, Watanabe K, Matsuo-Takasaki M, Kawada M,
Yonemura S, Matsumura M, Wataya T, Nishiyama A, Muguruma K,
Sasai Y: Self-organized formation of polarized cortical tissues
from ESCs and its active manipulation by extrinsic signals. Cell
Stem Cell 2008, 3:519-532.
Together with [33] this is the first demonstration of efficient generation of
cortical neurons in vitro, following a precise temporal pattern similar to in
vivo. In addition, the authors present evidence that a self-organized neural
cytoarchitecture can emerge in a purely in vitro setting.
48. Javaherian A, Kriegstein A: A stem cell niche for intermediate
progenitor cells of the embryonic cortex. Cereb Cortex 2009,
19(Suppl. 1):i70-i77.
49. Conti L, Pollard SM, Gorba T, Reitano E, Toselli M, Biella G, Sun Y,
Sanzone S, Ying QL, Cattaneo E, Smith A: Niche-independent
symmetrical self-renewal of a mammalian tissue stem cell.
PLoS Biol 2005, 3:e283.
50. Koch P, Opitz T, Steinbeck JA, Ladewig J, Brustle O: A rosettetype, self-renewing human ES cell-derived neural stem cell
with potential for in vitro instruction and synaptic integration.
Proc Natl Acad Sci U S A 2009, 106:3225-3230.
51. Gabay L, Lowell S, Rubin LL, Anderson DJ: Deregulation of
dorsoventral patterning by FGF confers trilineage
differentiation capacity on CNS stem cells in vitro. Neuron
2003, 40:485-499.
52. Elkabetz Y, Studer L: Human ESC-derived neural rosettes and
neural stem cell progression. Cold Spring Harb Symp Quant Biol
2008, 73:377-387 Epub.
53. Vanderhaeghen P, Polleux F: Developmental mechanisms
patterning thalamocortical projections: intrinsic, extrinsic and
in between. Trends Neurosci 2004, 27:384-391.
Current Opinion in Neurobiology 2010, 20:37–43