Methods

Reagents Dulbecco's Modified Eagles' Medium (DME) and Ham's F-12 (F-12) growth medium were obtained from Gibco Diagnos-tics, Grand Island, New York. Fetal calf serum (fcs) and trypsin-versene solution (0.05%, 0.02%) were obtained from Biofluids, Rockville, Maryland. Serum-free growth media com-ponents were obtained from Collaborative Research, Lexington, Massachusetts. Bovine type I collagen was obtained from Flow Laboratories, McLean, Virginia. Reagents for the preparation of routine solutions were the highest quality available from Fisher Scientific, Atlanta, Georgia. Enzymes and co-enzymes for histochemistry were obtained from Sigma Chemical Company, St. Louis, Missouri. Tissue culture plasticware was of the Corning trademark and obtained from Fisher Scientific. Triple-distilled water was utilized for the preparation of cell culture reagents. Antiserum to human factor VIII RAg and Tamm-Horsfall glycoprotein were obtained from Cappel Laboratories, Cochranville, Pennsylvania. Antiserum to keratin was a gift from Dr. Howard Green, Harvard Medical School, Boston, Massachusetts. Antiserum to human carbonic anhy-drase was a gift from Dr. RE Tashian, University of Michigan Medical School, Ann Arbor, Michigan.

Kidneys for explant Human kidneys utilized for establishing explant cultures were obtained from three sources. Cadaver kidneys donated for transplant which did not meet specifications were obtained after accession and examination in the Surgical Pathology Department of the Medical University of South Carolina, Charleston, South Carolina. Kidneys were also obtained from autopsy cases initiated within 6 hr of death from subjects unaffected with kidney or kidney-related disease. Portions of kidney cortex uninvolved in the disease state were also obtained from kidneys removed at surgery for such diseases as renal cell carcinoma. In these cases tissue was obtained following accession and exami-nation by Surgical Pathology and after completion of all diagnostic protocols. The use of human tissue was reviewed and approved by the Medical University of South Carolina Institutional Review Board for Human Research.