Are There Renal Stem/Progenitor Cells in the Adult Kidney?
The adult kidney has a low rate of turnover under steady-state conditions (31), suggesting that there is a cellular source for kidney remodeling and maintenance. Unlike regeneration after injury, tubular cell dedifferentiation, re-entry into the cell cycle, and epithelial-to-mesenchymal conversion have not been observed under normal conditions. After injury, kidney cells proliferate and differentiate to restore structure and function. After ischemia/reperfusion injury, regeneration of tubules starts in the third day, and after 10 d, 50% of the tubules have regenerated (32). Complete restoration of tubular morphology may take up to 4 wk (33 35). We and others have shown that extrarenal cells can contribute to renal repair. However, the degree of structural contribution is believed to be in the range of 1 to 8% (25 27). It is not clear whether extrarenal cells contribute to the recovery of renal function. Kale et al. (28) observed normalization of blood urea nitrogen toward control level
The adult kidney has a low rate of turnover under steady-state conditions (31), suggesting that there is a cellular source for kidney remodeling and maintenance. Unlike regeneration after injury, tubular cell dedifferentiation, re-entry into the cell cycle, and epithelial-to-mesenchymal conversion have not been observed under normal conditions. After injury, kidney cells proliferate and differentiate to restore structure and function. After ischemia/reperfusion injury, regeneration of tubules starts in the third day, and after 10 d, 50% of the tubules have regenerated (32). Complete restoration of tubular morphology may take up to 4 wk (33–35). We and others have shown that extrarenal cells can contribute to renal repair. However, the degree of structural contribution is believed to be in the range of 1 to 8% (25–27). It is not clear whether extrarenal cells contribute to the recovery of renal function. Kale et al. (28) observed normalization of blood urea nitrogen toward control level
