Uptake and degradation of low density lipoproteins (LDL) by confluent, contact-inhibited bovine and human endothelial cells exposed to physiological concentrations of LDL.

Metabolism of low density lipoproteins (LDL) was studied in cultures of endothelial cells derived from bovine aorta or heart and from human umbilical veins. At low LDL concentrations nonconfluent cultures of bovine endothelial cells catabolized more LDL protein than contact-inhibited confluent cultures but this difference was reduced at high LDL concentrations. Nonconfluent human endothelial cells displayed also a higher rate of LDL degradation than their contact-inhibited counterparts, but this difference was less pronounced than in the bovine cells. Bovine endothelial cells grown in the presence of fibroblast growth factor metabolized less LDL than those cultured without fibroblast growth factor (FGF), but this difference was not consistent in the human endothelial cells. The data presented provide evidence that contact-inhibited confluent human endothelial cells are capable of catabolizing LDL when exposed to physiological concentrations of this lipoprotein.