Biochemical analysis of collagen and elastin synthesis in the balloon injured rat carotid artery

Abstract

Introduction: Balloon catheter denudation of the endothelium in the common carotid artery of the rat is routinely used as a model of neointimal lesion development. The response to endothelial denuding injury involves proliferation and migration of medial smooth muscle cells (SMCs), with the formation of a dramatically thickened neointima. While many studies have focused on the kinetics of the early proliferative and migration responses, much less attention has been paid to the pronounced accumulation of extracellular matrix that occurs as the neointima grows. The purpose of this study was to measure collagen and elastin content, and to assess collagen and elastin synthesis in injured rat carotid arteries. Methods: Male Sprague–Dawley rats were subject to balloon catheter injury of the left carotid artery using a 2F embolectomy catheter. Rats were sacrificed at different time points after injury, and both carotids left (injured) and right (uninjured and control) were used for measurement of elastin and collagen synthesis (7 days) and content (7, 21 and 60 days). Results: Elastin and collagen syntheses were significantly increased in the injured carotids at 7 days after injury. The increase in elastin synthesis was more dramatic (100% compared to control) than the increase in collagen synthesis (50% compared to control). Both elastin and collagen content were significantly increased by 21 days, and contents were further increased by 60 days in the injured carotid compared to uninjured controls. At 60 days, collagen content of the injured vessels was 2.09±0.01 mg/arterial segment compared to 1.32±0.08 mg/arterial segment in controls ( P=.01). Elastin content of injured vessels was 2.40±0.43 mg/arterial segment compared to 1.19±0.25 mg/arterial segment in controls ( P=.03). Conclusions: Collagen and elastin contents were significantly increased following injury of the rat carotid. This study provides for the first time a biochemical assessment of collagen and elastin in the balloon-injured rat carotid artery.