Organ Regeneration Based on Developmental Biology

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1.3.2 Development of the Ventral Telencephalon In Vitro

Once the telencephalic fate is determined, the DV pattern within the telencephalic
region can be modified by patterning signals (Xu et  al. 2010 ). Thus, for hPSC-
derived cortical tissues, treatment with Shh signals can generate more ventral
regions (LGE and MGE), depending on concentration and duration. Consistent with
this idea, subpallium differentiation by treating ESC-derived telencephalic tissues
with Shh has been achieved (Aubry et al. 2008 ; Danjo et al. 2011 ; Kadoshima et al.
2013 ; Eiraku and Sasai 2012 ; Li et  al. 2009 ). In addition, different levels of Shh
signal can selectively induce LGE- and MGE-type differentiation using SFEBq cul-
ture (Fig. 1.1c).
The NE of the cortex is Pax6+/Gsh2−, whereas subpallium NE cells are Pax6−/
Gsh2+, and Nkx2.1 is expressed in the MGE and preoptic area, but not in the LGE
or CGE (Corbin et al. 2003 ; Nery et al. 2002 ). The majority of subpallium-derived

A B

C

E10. 5

E12. 5

: Nkx2.1(+)

: Gsh2(+)

LGE

MGE

: Foxg1(+)

: Gsh2(+)

: GAD65/67(+)

Nkx2.1/Gsh2/DAPI

SAG 30nM day15-2 1

SAG 500nM day15-2 1

: Nkx2.1(+)

: Gsh2(+)

: GAD67(+)

: Dlx2(+)

Fig. 1.5 Induction of ventral telencephalon. (a) Developmental process of ventral telencephalon
in mice. Previous studies have demonstrated that Shh is first observed at an early developmental
phase (E8-E9.5) in the diencephalon and mesendoderm adjacent to the ventral telencephalon, and
Shh induces Nkx2.1 in the MGE area. Then, Shh is expressed in the MGE and preoptic area by
E12.5, and Gsh2 is expressed between Nkx2.1 and Pax6 domain, and Gsh2+/Nkx2.1− domain pos-
sesses LGE identity. Also the eminence structure emerges during this period. (b) Schematic of
human ES cell-derived cortex–LGE tissues induced by a moderate treatment with SAG. Continuous
tissue including cortical (Pax6+) and LGE (Gsh2+) domains was generated in sequential order, as
seen in vivo. A mass of GAD65+ GABAergic neurons was generated underneath the Gsh2+ LGE
NE, whereas the rest of the telencephalic NE was largely positive for the cortical NE marker Pax6.
(c) Higher concentrations of SAG (500 nM, days 15–21) induced the medial ganglionic eminence
(MGE) marker Nkx2.1 at the cost of Pax6 and Gsh2 expression. Scale bar: 100 μm

T. Kadoshima et al.