Recent advances in renal regeneration

Regeneration of a functional kidney from pluripotent stem cells (PSCs) is challenging because of its complex structure. Kidneys are derived from embryonic metanephros, which are composed of three progenitor cells: nephron progenitors, ureteric bud, and stromal progenitors. Nephron progenitors and ureteric bud have been induced successfully from PSCs as a result of the understanding of their detailed developmental process through cell-lineage tracing analysis. Moreover, these induced progenitors can be used to reconstruct the three-dimensional (3D) structure of kidneys in vitro, including glomeruli with podocytes, renal tubules, and the branching ureters. Induction of the remaining renal progenitors (that is, stromal progenitors from PSCs and the further maturation of reconstructed kidneys) needs to be studied extensively to regenerate functional and sophisticated kidneys from PSCs. In addition to the proper induction of renal progenitors, new bioengineering methods such as decellularization and 3D bioprinting and the recent advancements in the regeneration of kidneys in other species are promising leads for regenerating the complex spatial arrangement of kidneys, including the vascular network and urinary excretion pathway in humans.