Tissue culture of normal rat glomeruli. Isolation and morphological characterization of two homogeneous cell lines.

Glomeruli were isolated from rat kidneys using enzymatic digestion, sieving and differential centrifugation. They were cultured in RPMI medium containing 15 per cent decomplemented fetal bovine serum. Using 3H-thymidine, two peaks of cell division occurred: the first was observed after 2 days in culture and reached its maximum on day 6; the second peak, starting on day 12, reached its maximum on day 22. Two cell types were identified by phase contrast, immunofluorescent and transmission electron microscopy. The first peak contained epithelial cells until day 6, while the second contained smooth muscle-like (mesangial) cells on day 30. The difference in the growth capacity of epithelial and smooth muscle-like cells allows their separate isolation by performing subcultures on day 6 for the former cells and on day 30 for the latter.