Adult mouse kidney stem cells orchestrate the de novo assembly of a nephron via Sirt2‐ modulated canonical Wnt/β‐catenin signaling

Abstract

End‐stage renal disease affects an estimated 2.4 million people annually worldwide. With cases increasing 8% every year, regenerative strategies are needed to help alleviate, and potentially replace, the increasing demand for kidney transplants. An important question remains whether stem cells reside in the adult mammalian kidney. Here we developed a methodology for isolation of kidney stem cells from adult mouse kidney by using Sca1 and Oct4 stem cell markers. Using these cells, we generated three types of kidney‐like structures. First, we observed the assembly of self‐organizing three‐dimensional kidney organoids. These kidney organoids show characteristic of kidney structures and contain podocytes and endothelial cells that form networks of capillary loop‐like structures. We also observed the de novogeneration of a self‐organizing nephron (and its associated collecting duct) from monolayer cultures. Comma‐ and S‐shaped bodies that expressed activated Notch1 were present during this formation, suggesting that Notch signaling played a key role in driving nephrogenesis. This is consistent with our current knowledge of nephron formation in the mouse embryo. Furthermore, we observed the differentiation of monolayer cells into functionally mature tubules and self‐organizing kidney‐shaped structures that selectively endocytose dextran. Finally, we demonstrated that expression of Sirt2 was upregulated, which modulated the dynamics of canonical Wnt/β‐catenin signaling during kidney organoid development. Altogether, our observations provide the first evidence for the existence of stem cells in the adult mouse kidney. These findings offer powerful tools for future applications, including drug screening, disease modelling, cell therapy, and kidney regeneration.