HUMAN GLOMERULAR VISCERAL EPITHELIAL-CELLS SYNTHESIZE A BASAL LAMINA COLLAGEN INVITRO

Isolated human glomeruli were digested with purified bacterial collagenase yielding epithelial cells. These cells grew to saturation density and did not become multilayered. They were identified as visceral glomerular epithelial cells by their morphologic appearance by phase and electron microscopy and by the presence of surface receptors for C3b. Neither Factor VIII antigen nor Fc receptors were observed. The glomerular epithelial cells synthesized a collagenous protein that was antigenically similar to human glomerular basal lamina. Proteins precipitated from visceral epithelial cell medium with affinity purified antibody against noncollagenous glomerular basal lamina antigens yielded a single collagenase labile protein that by sodium dodecyl sulfate/polyacrylamide gel electrophoresis migrated with an apparent M(r) of 168,000 in the presence of reducing agents. Analysis of hydroxyproline isomers yielded a ratio of 3-hydroxyproline to total hydroxyproline of 0.17. Pepsin digestion yielded a disulfide-bonded multimer which, with reduction, migrated with an apparent M(r) of 148,000. These data demonstrate that human glomerular visceral epithelial cells can be isolated and propagated in vitro and that they synthesize a collagen similar to that found in vivo.