Analysis of the role of apoptosis and cell proliferation in renal cystic disorders.

Cell proliferation and apoptosis were studied in 8 patients with inherited polycystic kidney disease and in 34 patients with acquired cystic kidney conditions including solitary and multilocular cysts and segmental tubular dilation. Intact renal tissue of 20 surgically removed tumorous kidneys served as control. Cell proliferation and apoptosis were demonstrated by immunohistochemical and in situ end-labeling methods. The percentage of positively stained nuclei was calculated and statistically analyzed. Both apoptosis and cell proliferation were significantly higher (p<0.001) in polycystic kidney disease. The percentage of positively stained nuclei in the whole kidney tissue with acquired cysts did not differ from controls although cell proliferation was significantly higher (p<0.001) in cells lining the cysts. Apoptotic cells were rarely found in the cystic epithelium or were even absent in these cases. Our data indicate that while polycystic kidneys seem to be characterized by abnormal cell survival, acquired renal cysts have different behavior in which so far unknown intracellular changes are more likely to cause tubular distension probably through induced cell proliferation.