Table 2 Summary for cellular composition and tissue type in brain organoid

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]