Mechanisms of the changes in the rate and nature of reparative regeneration of the aortic endothelium after repeated injuries

An experimental model of repeated cryogenic lesions in the rat abdominal aorta endothelium with a concentrically decreasing area of the defect has been worked out. In reendothelization of every successive defect participate the cells of the endothelial layer that is formed anew after the preceding lesions. As a result of repeated lesions the regeneration rate increases by 1.2 times. By means of scanning radioautography after 3H-thymidine++ administration the index of the labelled nuclei of the endothelial cells (EC) has been demonstrated to increase by 2.2 times. In the experiments with gamma-irradiation of the vessel before the last cryodestruction (this results in blockade of proliferation) an increased rate of EC migration has been revealed. Repeated lesions also produce an increase in the heteromorphism degree of the endothelial layer. This is mainly manifested as appearance of multinuclear EC clusters. These changes in rate and in character of the endothelium regeneration can be determined by the mechanisms similar to clonal proliferative senescence of EC in vitro.