This proposal is part of an ongoing program to develop artificial equivalents of the renal glomeruli and tubules. The present application proposes to identify the best combination of synthetic materials, biologic compounds, and cell components to produce a bioartificial renal tubule. Renal tubular progenitor cells will be grown as a confluent monolayer on biomatrix material lining the internal surfaces of hollow fibers. The function of these tubules, singly and in aggregates, will be assessed under various conditions and the best configuration determined.