Autosomal dominant polycystic kidney disease is a condition mainly characterized by the progressive development and enlargement of cysts in each kid neys. In this process a high rate of proliferation and apoptosis of tubular cells has been documented and interpreted as a futile attempt of tissue repair. In consideration of the role of stem cells in reparative processes we investigated the presence and localization of CD133 + CD24+ renal progenitors in renal ADPKD tissue and cells. Methods: Two

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... ormal kidneys and two ADPKD kidneys were examined. CD133 and CD24 expression was investigated by confocal microscopy and immunoblotting. Furthermore cystic isolated cells and cultured immortalized cells were characterized. Results: CD133 and CD24 have the same localization in ADPKD tissues and in normal kidneys: expression is restricted to a subset of epithelial cells (PEC) of Bowman's capsule and to tubular cells in a focal and segmental pattern. Furthermore, in ADPKD tissue, cysts diffusely express CD133 and CD24. According to a quantitative analysis in ADPKD tissue CD133 + CD24 + cells are statistically more expressed in tubules (p < 0.001) and less expressed in the Bowman's capsule (p = 0.0016) compared to the same localizations in control tissue. Conclusions: CD133 and CD24 antigens, typically expressed by renal epithelial progenitors, are more expressed in ADPKD tubules and highly expressed in ADPKD cysts. Whether CD133 and CD24 expression would signify renal progenitor recruitment or alternatively an expression pattern of the dedif-ferentiation of ADPKD cells remains unclear.