[Role of foam cells in lipoprotein transformation within the vascular wall]

Foam cells were isolated from atherosclerotic aortas of rabbits following their intima incubation with collagenase and elastase. The viability of the cells, their incidence and nativity were supported histochemically and electron-microscopically. The interaction of the foam cells with lipoproteins was studied in vitro with perfusions of isolated atherosclerotic aortas of rabbits during 6 hours with a medium containing beta- and pre-beta-lipoproteins labelled with I125 or simultaneously with I125 and C14-cholesterol. It was found that after the perfusion the foam cells contain a much higher proportion of radioactivity of the total lipids, cholesterol and cholesterol esters, to that of the proteins, than the perfusate. The foam cells must selectively "capture" the lipids from the lipoprotein particles. The proportion "free cholesterol/cholesterol esters" (according to the radioactivity) proved to be much higher in the foam cells than in the perfusate. The possible mechanisms of the participation of the foam cells in the metabolism of lipoproteins and in the pathogenesis of atherosclerosis are discussed.