Fig. 2

Generation of lung organoids from hPSCs. Different types of lung organoids can be harvested from directed differentiated hPSCs by controlling the compositions of the medium in a 3D Matrigel culture. For proximal airway organoids, “CFK media” can be chosen, which contains CHIR99021 (3 μM), recombinant human FGF (rhFGF) 10 (10 ng/mL), and recombinant human keratinocyte growth factor (rhKGF; 10 ng/mL), or another “2 + 10 media” containing rhFGF2 (250 ng/ml), rhFGF10 (100 ng/ml), DCI (50 nM dexamethasone, 0.1 mM 8-Bromoadenosine 3′,5′-cyclic monophosphate sodium salt and 0.1 mM 3-Isobutyl-1-methylxanthine), and Y-27632 [11]. For alveolar organoids, cells can be cultured in “CK + DCI” medium, which comprises CHIR99021 (3 μm) and rhKGF (10 ng/ml), additional Y-27632, and other growth factors or cytokines, such as EGF and TNFα [12]. Induced hPSCs, undergoing the steps of definitive endoderm (DE) and anterior foregut endoderm (AFE), can be treated with branching media to develop into lung bud organoids (LBOs). The latter could branch out and simulate lung tissues in Matrigel in 24-well transwell inserts if branching medium is added [13]