The Accumulation of Serum Lipoprotein Cholesterol by Tissue Culture Cells 1

Abstract

Summary

β-Lipoprotein isolated from human or bovine serum elicited sudanophilic inclusion bodies within cultured fibroblasts. Such sudanophilia was accompanied by an increase in cellular cholesterol, about 2/3 of which was in the esterified form. The origin of the cholesterol appears to be largely from the deposition of β-lipoprotein-bound cholesterol ester instead of newly esterified cholesterol. Much of the accumulated cholesterol, especially the cholesterol ester, was found within the inclusion bodies. They should be particularly considered as being formed as the result of cholesterol ester uptake. Free cholesterol bound to bovine albumin also elicited intracellular sudanophilic inclusion bodies containing cholesterol ester. Free cholesterol in microcrystalline form did not lead to similar sudanophilia or increase in cellular cholesterol content.

This tissue culture system provided analogies to atherosclerosis in that cholesterol accumulated in the cells in both instances when the extracellular medium or plasma contained high concentrations of cholesterol bound to protein. In both instances, also, lipid droplet formation occurred and cholesterol ester accumulation was the chief form of the cholesterol overload.