Wound healing in the media of the normolipemic rabbit carotid artery injured by air drying or by balloon catheter de-endothelialization

Abstract

The response to air-dry injury to the carotid artery of the normolipemic rabbit was compared with the response to de-endothelialization with a balloon catheter. Air drying induced an inflammatory response that resembled arteritis rather than atherosclerosis. There was medial damage, neutrophil but not macrophage infiltration, and fibrin formation, limited smooth muscle proliferation, which regressed after 3 months, and no lipid deposition. Within 1 week the smooth muscle cells were mainly of the secretory phenotype, and a neointima had formed. At 4 weeks the neointimal proliferation continued, but most cells showed a contractile phenotype. By 3 months, the lesion consisted of fibromuscular thickening with few small smooth muscle cells. Balloon injury induced minimal medial damage and continuing intimal proliferation with no evidence of regression by 3 months. It is concluded that air drying the carotid artery induces smooth muscle damage as well as endothelial cell loss, and this stimulates a wound-healing mechanism that is different from the response to selective intimal injury.