Human fetal kidney organoids model early human nephrogenesis and Notch-driven cell fate.

Pluripotent stem cell (PSC)-derived kidney organoids are used to model human renal development and disease; however, accessible models of human fetal development to benchmark PSC-derived organoids remain underdeveloped. Here, we establish a chemically defined, serum-free protocol for prolonged culture of human fetal kidney-derived organoids (hFKOs) in vitro. hFKOs self-organize into polarized renal epithelium, reinitiate from NCAM1 progenitors, and recapitulate nephrogenic and ureteric bud lineages. Bulk transcriptomics, single-cell RNA sequencing, pseudotime analysis, and immunostaining revealed diverse renal tissue cell populations, with a preserved epithelial progenitor pool and tubular differentiation axis. hFKOs were enriched for Notch signaling genes, enabling single-cell analysis of pharmacological Notch inhibition. This revealed a maturation block with increased nephron progenitors and a shift toward distal over early proximal tubule fates. We also identified a novel prominin-1-expressing cell state that evades Notch inhibition to generate both proximal and distal tubules. Overall, hFKOs provide a faithful model to gain insights into human kidney development, advancing the fields of stem cell biology and regenerative medicine.