CELL-LINES WITH EXTENDED IN-VITRO GROWTH-POTENTIAL FROM HUMAN RENAL PROXIMAL TUBULE - CHARACTERIZATION, RESPONSE TO INDUCERS, AND COMPARISON WITH ESTABLISHED CELL-LINES

Few model systems exist for the study of injury to human renal proxima l tubule epithelium. Optimized differentiated human renal epithelial c ell lines with extended in vitro growth potential would provide an alt ernative model system to primary culture or other available non-human mammalian kidney cell lines. For this purpose, human renal tubule epit helial cells were isolated from normal kidney cortex and exposed in cu lture to a hybrid immortalizing virus, adenovirus 12-SV40. Cell lines were developed by limiting dilution, and three selected cell lines wer e screened for growth pattern, production of immortalizing virus, tumo rigenicity, and ploidy. Cell lines were also monitored for response to inducer agents and matrix factors and were screened for expression of biochemical properties and differentiation markers of renal epitheliu m. All three are nonproducers of the immortalizing virus and are nontu morigenic. They grow in monolayer, have intermediate growth kinetics, and express markers of renal proximal tubular epithelium by immunohist ochemistry. They also express biochemical properties comparable to oth er widely used proximal tubular cell lines including LLC-RK1, OK, and HK-2 and comparable to human tubular cells in stable culture. Growth m edium containing low levels of fetal calf serum, or epidermal growth f actor combined with parathyroid hormone, produced optimal growth chara cteristics, brush border enzyme expression, biochemical properties, an d glucose transport in a selected cell line. The addition of dimethyl sulfoxide allows maintenance in morphologically intact monolayers for prolonged periods. These cell lines should be useful model systems for the study of human renal proximal tubular injury or disease.