Distinct differences between cultured podocytes and parietal epithelial cells of the Bowman's capsule

Phenotypic changes in culture hamper the identification and characterization of cultured podocytes and parietal epithelial cells of the Bowman's capsule (PECs). We have recently established culture conditions that restore podocytes to their differentiated phenotypes. We compared podocytes and PECs cultured under the same conditions to determine the unique characteristics of the two cell types. Performing this comparison under the same conditions accentuated these differences. Podocytes behaved like non-epithelial cells by extending cell processes even at confluence. By contrast, PECs behaved like typical epithelial cells by maintaining a polygonal appearance. Other differences were identified using immunostaining and RT-PCR; podocytes expressed high levels of podocyte-specific markers while PECs expressed high levels of PEC-specific markers. However, while podocytes expressed low levels of PEC markers, PECs expressed low levels of podocyte markers. Therefore, the identification of podocytes and PECs in culture requires the evaluation of respective cell markers and the expression of markers for other cell types.