Endothelial cell injury in early mild hypercholesterolemia

Hypercholesterolemia was induced in 6-week-old male swine by feeding them a chow diet supplemented with lard and cholesterol. Aortic samples from areas of spontaneously-differing permeability to proteins, as demarcated by their uptake of Evans blue dye, were prepared and examined using light microscopy and scanning and transmission electron microscopy. At 2, 4, and 6 weeks after diet initiation, cholesterol/lard-fed animals demonstrated leukocyte adhesion to aortic endothelium in both greater (blue) and lesser (white) permeability areas, being greaer in the former. Endothelial cells underlying leukocytes were generally normal in ultrastructural appearance, but showed cytoplasmic uptake of ruthenium red. Endothelial cells in cholesterol/lard-fed animals contained more lysosomes and cytoplasmic filaments than seen in control animals. Blood-derived cells were more frequently seen in the intima of cholesterol/lard-fed animals, and were often observed associated with intercellular junctions in the endothelium.