Injury at the Vascular Surface

Abstract

The last ten years have seen an exponential growth in interest in, the role of the endothelium in atherosclerosis and in the idea that suggests that the cell affected by shear, the endothelial cell, may play a critical role in lesion formation. This interest has come from two quite different sources. First, there is the apparent coincidence of areas of high shear with areas with a propensity to develop atherosclerosis. Second, there is the biochemical evidence that the endothelial cell is intensively active in a number of metabolic functions capable of modulating lesion formation. All of this has tended to blur our lack of a definition for endothelial injury. For example, Ross’ and Harker’s (1976) discovery of the platelet-derived growth factor (PDGF) led to a major emphasis on denuding injuries as a site where platelets could interact with the vessel wall and stimulate smooth muscle proliferation. Actual studies of denuding injuries, however, have been very limited except over advanced lesions or in response to the balloon catheter. Studies of hypertensive or hyperlipemic animals have not shown denudations unless overt atherosclerotic lesions were already present (Schwartz et al. 1980; Hansson and Bondjers 1980).