Differential effects of isolated lipoproteins from normal and hypercholesterolemic rhesus monkeys on cholesterol esterification and accumulation in arterial smooth muscle cells in culture.

Whole serum obtained from hypercholesterolemic rhesus monkeys was found to stimulate cholesterol esterification and cholesteryl ester accumulation in rhesus monkey arterial smooth muscle cells in culture to a significantly greater extent than normocholesterolemic serum. This was true even when the cholesterol concentration of the culture medium was equalized. Isolation and characterzation of the low density lipoproteins (LDL) from rhesus monkeys indicated that the LDL from hypercholesterolemic animals was 33% larger than LDL from normocholesterolemic animals due principally to an increase in the amount of cholesteryl ester per molecule. As a result, LDL from hypercholesterolemic animals transported over 50% more cholesterol per molecule than did normal LDL. The LDL of altered composition from hypercholesterolemic animals, when added to smooth muscle cells in culture, was nearly twice as effective in stimulating cholesterol esterification and cholesteryl ester accumulation than was LDL of normal composition. Results suggest that at least part of the exaggerated ability of whole hypercholesterolemic serum to stimulate the esterification and accumulation of cholesterol in cells in culture is due to the presence of LDL of altered composition.