Building human renal tracts.

Severe kidney failure affects several million people worldwide. Among these are children born with abnormal renal tracts, and some carry mutations of genes active in renal tract development. Kidney transplants are in short supply, and long term dialysis does not obviate uraemia and its associated harmful effects. It has been envisaged that a combination of stem cell technology, developmental biology, and genetics will revolutionise our understanding of kidney disease and provide novel therapies for kidney failure. Here, we review progress towards making functional kidney tissues from human pluripotent stem cells. Organoids rich in immature glomeruli and tubules can be created in culture from pluripotent stem cells. Moreover, differentiation can be increased by implanting these cells into immunodeficient mice. Challenges remain to be overcome, however, before these tissues can be used for regenerative medicine therapies. Current limitations include the small size of an organoid, the lack of large blood vessels feeding it, and the lack of a urinary tract to plumb the kidney organoid. Pluripotent stem cell technology is also being used to create 'diseases in a dish' to understand the pathobiology underlying human renal tract malformations.