Primary Culture and Characterization of Human Renal Inner Medullary Collecting Duct Epithelial Cells

Abstract

Our understanding of physiological and pathophysiological events associated with inner medullary collecting duct epithelium is based on studies in cells isolated from mice and rats. We established primary cultures of hIMCD (human papillary collecting duct epithelial) cells. Normal papillary tissues were dissected from the surgical waste of consenting patients undergoing renal surgery. Tissues were digested enzymatically. Cells were maintained in Dulbecco's modified Eagle's medium supplemented with glucose and antibiotics. Cultures were treated with ethylenediaminetetraacetic acid and epithelial select medium was also used to obtain a pure epithelial culture. The hIMCD cells grew in a monolayer. Cells showed the expression of epithelial specific markers, including cytokeratin, the tight junction marker zonula occludens 1 and the cytoskeletal protein vimentin. They lacked expression of factor VIII, which is a glycoprotein synthesized by endothelial cells. To our knowledge we also noted for the first time uroplakin expression in collecting duct epithelial cells. This expression was maintained in primary culture. The hIMCD cells in culture were highly resistant to hypertonic solutions and they responded to hypertonicity by cyclooxygenase-2 over expression. Moreover, these cells also survived prolonged periods of hypoxia. To our knowledge this is the first report of successful culture and characterization of primary cultures of collecting duct epithelial cells from human renal papillae. These cells will serve as essential tools in helping us fill the gaps in our understanding of the events associated with the physiology and pathophysiology of human renal inner medullary collecting duct epithelium.