Injury to cultured endothelial cells induced by low density lipoproteins: protection by high density lipoproteins.

Cultured human endothelial cells derived from umbilical cord veins were injured when exposed to low density lipoproteins (LDL). Addition of high density lipoproteins (HDL), together with LDL, inhibited the cellular injury induced by LDL as demonstrated by lowered 51Cr release and prevention of morphological changes. Serum albumin had a similar, but far weaker effect. Preincubation of the cells with HDL did not reduce injury inflicted during a subsequent incubation with LDL, while preincubation with LDL aggravated later damage. The protective effect of HDL could be overcome by increasing the DLD concentration.