Sera containing elevated nonesterified fatty acids from patients with angiographically documented coronary atherosclerosis cause marked lipid accumulation in cultured human arterial smooth muscle-derived cells

Abstract

Sera from 47 angiography patients were included in medium supporting the growth of human arterial smooth muscle-derived cells (HUSMC). Ten sera from the 38 patients demonstrating significant coronary artery obstruction caused marked cellular accumulation of neutral lipid, causing the cultured cells to resemble the foam cells of atherosclerotic plaque. None of the sera from the 9 non-atherosclerotic patients caused such marked steatosis. A lesser degree of lipid accumulation by the cultured cells was seen for 4/38 atherosclerotic and 2/9 non-atherosclerotic patients sera. The cell lipids were analyzed by thin layer chromatography and were shown to be triglyceride (TG). The quantities of neutral lipids which accumulated in cultured HUSMC were estimated by absorbances due to Oil red O staining of lipid which were normalized to total cell protein based on absorbances due to Coomassie brilliant blue G-250 staining, yielding specific lipid content index values. Serum nonesterified fatty acids (NEFA) concentrations and NEFA/albumin molar ratios were strongly and significantly correlated with specific lipid content index values ( r = 0.870, P < 0.001; r = 0.828, P < 0.001, respectively), while total cholesterol and TG concentrations did not yield significant associations. The observed steatosis could be reproduced in HUSMC by the addition of exogenous NEFA to the culture medium. Measurements of proliferation of the cultured HUSMC showed no differences between sera causing lipid accumulation and sera lacking this effect. It is suggested that circulating NEFA concentrations may play a role in the etiology of atherosclerotic plaque.