Fig. 2.

hPSC differentiation approaches. Undifferentiated hPSCs can be expanded under standard maintenance culture conditions (top), and subsequently differentiated using different methodologies (Morizane et al., 2015; Qian et al., 2016; Takasato et al., 2015). The formation of embryoid bodies (middle) recapitulates early developmental events, including the three germ layers – the ectoderm, mesoderm and endoderm. Recent advances in 3D culture techniques have allowed the generation of organoids (bottom), which possess high tissue complexity and tissue-specific functional activity. These include layers of differentiated cells in close cell­–cell and cell–extracellular matrix contact. One of the important challenges in the organoids field is the formation of a vasculature. To date, only two studies of kidney organoids have shown the expression of vasculogenesis markers (Takasato et al., 2015; Czerniecki et al., 2018). Scale bars: 200 µm (top and middle), 500 µm (bottom). Contrast-phase images are courtesy of E.G.