Injury to human endothelial cells in culture induced by low density lipoproteins

Low density lipoproteins (LDL) have been shown to injure culture endothelial cells derived from the human umbilical cord. During a 48 h incubation period LDL significantly increased 51Cr release from prelabelled cells and induced marked cellular injury if the ratio between the LDL cholesterol and the infranatant proteins was kept above 0.1-0.12 mmol/g protein. Actually, an injurious effect of a fixed concentration of LDL could be completely prevented by increasing the concentration of infranatant proteins. High density lipoproteins within physiological concentration ranges had no effect when tested in the presence of infranatant proteins. The effects of LDL were not cell specific because normal as well as LDL receptor negative human skin fibroblasts were injured by LDL.