Recent advances in molecular pathology: Arterial endothelium—Assessment of in vivo injury

Abstract

Within the last 10 years there has been considerable interest in vascular endothelium, and in part this is because of the critical role that the endothelial monolayer plays in atherosclerosis (Ross and Glomset, 1976; Ross et al., 1977; Ross, 1981). A widely held concept in atherosclerosis research is that loss of endothelium precipitates intimal lesion development through the interaction of platelets and their mitogens on the underlying cells in the denuded vessel. A break in the integrity of the endothelium therefore becomes an important issue, and considerable research efforts have been concentrated on what factors are capable of injuring the endothelium. The purpose of this article however is not to review which agents lead to endothelial injury and denudation, but rather to concentrate on the criteria by which we make the assumption that all is not well with the endothelium. At first sight it may seem obvious that endothelial loss is the only meaningful criteria to assess any disruption of the endothelium, but due to circumstances such as size of injury, speed of endothelial repair, nonthrombogenic smooth muscle, as well as just sampling error, this obvious event can be overlooked. The purpose of this article, therefore, is to review the various criteria by which endothelial injury and loss have been assessed and also to examine what happens to the underlying vessel wall after these injuries.