Table 2.

Summary for cellular composition and tissue type in brain organoid

Cell or tissue type	Organoid type	Days of differentiation	Characteristics	Sources	References
Neural progenitor cells	Dorsal forebrain	7–28 days	Located at ventricular zone	hiPSC	Lancaster & Knoblich, 2014 [27]; Qian et al.,2019 [28]; Wang, L et al., 2020 [29]
Glutamatergic neurons	Human cortical spheroid	15 weeks	Generated repetitive action potentials at depolarization. vGLUT	hIPSC	Yoon et al., 2019 [30]; Xiang et al., 2020 [31]; Zafeiriou, M et al., 2020 [15]
GABAergic neurons	Ventral forebrain	2 months	GABA, GAD67	hiPSC	Birey et al., 2017 [32]; Zafeiriou, M et al., 2020 [15]
Cortical interneurons	Forebrain assembloids	1–1.6 months post assembly	Migrate in a saltatory pattern and integrate into cortical microcircuit. SP8, GSX2	hiPSC	Birey et al., 2017 [32]; Xiang et al., 2017 [33]; Tanaka Y et al., 2020 [34]
Dopaminergic neurons	Midbrain	≥ 3 months	FOXA2, TH	hiPSC	Jo, J. et al 2016 [18]; Qian, X. et al., 2018 [10]; Smits L M et al., 2019 [17];
Hypothalamic/peptidergic neurons	Hypothalamus	≥ 3 months	Rax1, POMC, OTP	hiPSC	Qian, X. et al., 2018 [10]; Miura Y et al.,2019 [19]
Astrocyte	Asteroids	9–20 months	GFAP	hPSC	Sloan et al., 2017 [35]; Zafeiriou, M et al., 2020 [15]; Yakoub 2019 [36]
Microglia	Dorsal forebrain/organoid-grown microglia	13–52 days	IBA-1, IL34, CSF1, and TGFB1	Mesodermal progenitors	Ormel et al., 2018 [25]; Song, L et al., 2019a [37]
Oligodendrocyte	Oligocortical spheroids	5–8 months	OLIG2; MBP/CNP	hPSC	Madhavan et al., 2018 [38]; Zafeiriou, M et al., 2020 [15]
Optic vesicle (OV)-like structures	Retinal organoids	4–23 weeks	Possesses dense translucent projections at the apical edge that grow. OTX2, CRX	hiPSC-derived LCA4 patient	Lukovic et al., 2020 [39]; Brighi et al.,2020 [40]; Takata N et al., 2017 [41]