Lipid accumulation in the neointima formed in normally fed rabbits in response to one or six removals of the aortic endothelium.

In previous experiments it was shown that repeated mechanical or immunologic injury to the arterial intima of normally fed rabbits induced lesions morphologically identical with human atherosclerosis. These regressed in size and lipid content when the injury stimulus was removed. By contrast, repeated injury directed to removal of only the endothelial layer induced lesions in which lipid accumulated in areas of endothelial regeneration and increased with time. In the present report the lesions associated with multiple and with a single episode of endothelial removal, using a Fogarty balloon catheter, are compared. Lipid accumulates in areas of endothelial regrowth following one endothelial injury and is similar in amount to that at comparable time intervals following the first of multiple balloon removals of the endothelium. There is much more lipid in areas of endothelial regrowth than in areas that remain uncovered by endothelium, the lipid tends to increase with time, and there is more lipid in the abdominal aortic than in the thoracic aortic lesions. A correlation was found between lipid content and thickness of lesions, especially in response to multiple removals of the endothelium. Multiple removals resulted in thicker lesions than a single injury. There appeared to be a positive relationship between the level of blood cholesterol and the amount of lipid deposited in areas of endothelial regrowth. This is consistent with trapping of low density lipoprotein by glycosaminoglycans in the neointima covered by regenerated endothelium.