Accelerated endothelial regeneration and intimal hyperplasia following a repeated denudation of rabbit carotid arteries: morphological and immunohistochemical studies.

1. We compared endothelial regeneration and intimal thickening after endothelial denudation between normal and sclerotic carotid arteries (CA). Endothelial denudation of the right CA of rabbits formed intimal thickening covered with regenerated endothelial cells (EC) in 6 weeks, which was considered as the sclerosis model. Both CA were then denuded. Morphological and immunohistochemical studies using antibodies for proliferating cell nuclear antigen (PCNA), von Willebrand factor and macrophages were performed. 2. Regeneration of EC were observed 24 h after denudation on both CA, but completed earlier in the double-denuded right CA. The density of EC in both CA increased after regeneration and gradually decreased afterwards. 3. After a single denudation on the left CA, PCNA-positive cells clearly appeared in 24 h, markedly increased in 72 h both in the intima and media, then greatly decreased in 4 and 6 weeks. 4. After a double denudation of the right CA, enhancement of the intimal hyperplasia was observed. PCNA-positive cells markedly increased in 1 week and remained significantly increased in 6 weeks both in the intima and the media. 5. We concluded from these results that the repeated endothelial denudation caused more sustained proliferation of smooth muscle cells which led to an enhancement of the intimal hyperplasia.