Abstract
Purpose of review: Kidney organoids are heterocellular structures grown in vitro that resemble nephrons. Organoids contain diverse cell types, including podocytes, proximal tubules, and distal tubules in contiguous segments, patterned along a proximal-to-distal axis. Human organoids are being explored for their potential as regenerative grafts, as an alternative to allograft transplants and hemodialysis. Earlier work, analyzing grafts of developing human kidney tissue and whole human embryonic kidney rudiments, serves as a baseline for organoid implantation experiments. Recent findings: When transplanted into immunodeficient mice beneath the kidney capsule, kidney organoid xenografts can form vascularized, glomerulus-like structures, which exhibit a degree of filtration function. However, the absence of an appropriate collecting duct outlet and the presence of abundant stromal-like cells limits the functionality of such grafts and raises safety concerns. Recently, ureteric-like organoids have also been generated, which extend projections that resemble collecting ducts. Summary: Combining nephron-like and ureteric-like organoids, along with renal stromal cells, may provide a path towards more functional grafts.