Isolation and characterization of endothelial cells from the epididymal fat pad of the rat.

Endothelial cells from rat epididymal fat pad capillaries were isolated from rats immediately after weaning. The cells were obtained after an initial brief incubation with collagenase under conditions of minimal breakage of cells. Adipocytes were removed by flotation and endothelial cells were then obtained as cell aggregates by fractional filtration procedures whereby intact tissue as well as free cells were removed. These aggregates were then dispersed and cultured in supplemented medium 199 whereby a monolayer of cells with a growth pattern, numerous pinocytotic vesicles, and intercellular junctions typical of endothelial cells were obtained. Minor contaminations of precursor cells to adipocytes were absent after one subculture. Here greater than 95% of the cells showed the presence of Factor VIII. Further subcultures produced nonhomogenous cells and decreasing rates of replication. The endothelial cells showed a very low rate of triglyceride synthesis and release, and collected no visible lipid upon prolonged cultures in the presence of an abundance of triglyceride substrate. They bound lipoprotein lipase from rat adipocytes, whereby the lipase was stabilized. This binding was released by heparin, and the cells did not synthesize the enzyme.