Organ Regeneration Based on Developmental Biology

3

induced pluripotent stem (iPS) cells), which can recapitulate complex organ struc-
tures, offer us a new opportunity to understand human brain development and apply
our findings to regenerative medicine and drug discovery (Eiraku et  al. 2008 ;
Kadoshima et al. 2013 ; Lancaster et al. 2013 ; Kamiya et al. 2011 ).
Here we review recent progress in the 3D organ generation of various telence-
phalic regions from PSCs based on developmental biology. First, we review the
basic features of in vivo development, along with recent progress in in vitro cortical
tissue generation from PSCs. Then, we focus on the generation of ventral
telencephalic regions, followed by the generation of dorsal telencephalic regions
including the hippocampus.

MGE

LGE

dorsolateral

pallium

cortical hem (cerebral cortex)

choroid

plexus

Wnt

BMP

Shh

medial

pallium

dorsal

ventral

rostral

caudal

spinal cord

hindbrain

forebrain midbrain

Wnt

RA

FGF

AB

telencephalon

diencephalon

suspension culture

in growth-factor-minimized

serum-free medium

dissociated ESCs

quick reaggregation

SFEBq culture

cortex

choroid plexus

medial pallium

BMP+Wnt

(+ + +)

Shh(+)

BMP+Wnt (+)

Shh

(+ + +)

Te lencephalic

neural progenitors

(Foxg1+)

TGFβ

Wnt

LGE

MGE

C

Fig. 1.1 In vivo neural development and differentiation strategy of SFEBq culture. (a) Regional
patterning of neural plate. During early neural development, the neural tube is subdivided into the
forebrain, midbrain, hindbrain, and spinal cord along the AP axis. The forebrain comprises the
telencephalon and diencephalon. The early neural progenitors exhibit the anterior identity initially
and are subsequently patterned by caudalizing signals such as Wnt, RA, and FGF. (b) Schematic
of the developing fetal telencephalon. Along the DV axis, ventralization of telencephalic progeni-
tors is promoted by the Shh signal, and dorsalization is caused by BMP and Wnt signals. (c) In
SFEBq culture of human ESCs, 9000 cells are quickly reaggregated using a low-cell-adhesion
96-well culture plate. The floating aggregates are cultured in growth factor-minimized serum-free
medium. In the absence of Wnt signals, the tissue differentiates into Foxg1+ telencephalic precur-
sors. For the dorsalization of telencephalic tissues, aggregates are treated with BMP4 ligand plus
CHIR 99021 (GSK3 inhibitor, also known to accelerate Wnt signaling). For the ventralization of
telencephalic tissues, aggregates are treated with the hedgehog agonist SAG

1 Telencephalic Tissue Formation in 3D Stem Cell Culture