Endothelial healing in the rabbit aorta and the effect of risk factors for atherosclerosis. Hypercholesterolemia

The effect of diet-induced moderate hypercholesterolemia on endothelial healing has been investigated in the rabbit following a narrow superficial injury to aortic endothelium without damage to the media of the vessel. The healing process was compared with that observed in normocholesterolemic animals. The degree of platelet involvement was similar in both normo- and hypercholesterolemic animals. Reendothelialization occurred within 48 hours in both groups of animals, showing that hypercholesterolemia did not delay endothelial healing. It was found that esterase-positive cells, which morphologically resembled monocyte-macrophages, adhered to and penetrated regenerated endothelium only in hypercholesterolemic animals. After reendothelialization in normocholesterolemic animals, there was no increase in the number of cells within the intima of the vessel and no evidence of lipid accumulation. In hypercholesterolemic animals, cells accumulated in the intima in areas of regeneration, and lipid accumulation occurred within both the intima and the media in areas of regeneration.