Fig. 1

Multiple stem/progenitor cells in kidney, which are located in kidney in situ or originated from circulation, especially bone marrow. Furthermore, there are differences in these kidney-derived stem/progenitor cells considering their location. Stem/progenitor cells in glomeruli are CD24⁺CD133⁻-MSC-like cells. The CD133⁺CD24⁺CD106⁺-stem/progenitor cells are primarily located in urinary pole in Bowman’s capsule. Those cells closer to the urinary pole have more activities than those closer to the vascular pole. CD133⁺CD24⁺CD106⁻ cells are in tubules, especially proximal tubules, with fewer mitochondria and less cytoplasm and without brush border than other tubular epithelial cells. In addition, CD90⁺Pax-2⁺CD133⁻-MSC-like cells, Pax-2⁺ tubule-like cells, and Pax-8⁺ cells also locate in tubules. Notably, Sox9⁺Lgr4⁺CD133⁺Pax-2⁻ cells, primarily located in proximal tubules with epithelial polarity and brush border, could differentiate into proximal tubule, loop of Henle, and distal tubule segments, but not into collecting duct. In S3 segment of nephron, there is a group of Pax-2⁺ stem/progenitor cells, which have the perfect repair capabilities although they have an immature tubular epithelial-like phenotype. Renal papilla is also a niche for renal stem/progenitor cell homing. These CD24⁺CD133⁺ spindle-shaped cells are primarily located in the very outer part of the papilla which is in close proximity to tubules. Besides, there are also pericytes and CD133⁺-kidney-resident MSCs close to the vessel in the interstitium