FIGURE 1.

Schematic stepwise description of the differentiation of kidney organoids from hPSCs. After treatment of hPSCs with factors and small molecules according to chosen protocol posterior primitive streak is induced. Further treatment with renal inductive signals leads to intermediate mesoderm (IM) commitment. Specifically, in our protocol, this step is characterized by the formation of a tight monolayer of IM committed cells on Day 4 of differentiation. IM-comitted cells are treated with a short pulse of CHIR, then aggregated to spheroids and further stimulated with FGF9 signalling until Day 11 to induce the formation of renal vesicels (RVs), which are visible at the borders of the organoid (yellow arrows). Upon removal of factors, RVs develop into tubular and glomerular structures (red arrow heads) to generate kidney organoids by Day 20 of differentiation. Scale bars, 100 µm.