New Insights into the Renal Progenitor Cells and Kidney Diseases by Studying CD133

CD133(+) progenitor cells have been found in different segments of the human nephron. In particular, CD133-expressing cells are present in the cortex, in Bowman's capsule of the glomerulus, and in proximal convoluted tubules and in medulla, in the Henle's loop, and its thin limb segments. The collecting ducts are negative. During repair of renal injury, CD133-expressing cells are increased, suggesting a contribution in renal regeneration. An increase has also been observed in pathological conditions. CD133(+) cells contribute to the formation of glomerular crescents and are lining the cysts in the polycystic kidney disease. Therefore, an altered regulation of CD133(+) cell proliferation or differentiation could be involved in glomerular and tubular response to injury in pathological condition. In clear cell renal carcinoma, despite CD133(+) cells appeared to contribute to tumor vascularization, they did not display features of tumor-initiating cells.