Mitosis and the presence of binucleate cells among glomerular podocytes in diseased human kidneys.

Podocytes are highly differentiated cells that appear to be postmitotic. However, it is unclear whether cell division or the proliferation of podocytes takes place in the setting of glomerular injury. In this study, we analyzed the presence of mitotic figures and of binucleate or multinucleate podocytes in diseased human kidneys by light and electron microscopy. Among the 164 cases analyzed, mitotic figures in podocytes were found in only one cell, in a case of focal and segmental glomerulosclerosis, and 6 cases provided evidence of two or more nuclei in a single podocyte. Serial sections by light microscopy confirmed that the nuclei in multinucleate cells were separate and of approximately the same size. Electron-microscopic analysis of the binucleate podocytes revealed hypertrophy and effacement of foot processes. These findings indicate that, in human podocytes, mitosis without cytokinesis (cell division) results in binucleate cells in cases of glomerular injury.