VITAMIN-E INHIBITS THE INTIMAL RESPONSE TO BALLOON CATHETER INJURY IN THE CAROTID-ARTERY OF THE CHOLESTEROL-FED RAT

We have investigated the effect of the naturally occurring, lipid-soluble antioxidant, vitamin E, on the intimal response to balloon injury in the cholesterol-fed rat. We found that in animals receiving a 0.5% vitamin E plus 1% cholesterol diet, neo-intimal thickening was reduced by 30% (P < 0.025) compared to animals receiving either cholesterol alone, or a control chow diet. In all three dietary groups, the intimal lesion consisted predominantly of smooth muscle cells, and few monocytes/macrophages (<0.5%) could be identified by staining with the monoclonal antibody ED-1. In vitro, vitamin E inhibited platelet-derived growth factor- (PDGF) (20 ng/ml) and serum (2%)-induced mitogenesis of both adult rat thoracic aortic smooth muscle cells and an embryonic rat aortic smooth muscle cell line (A7r5), dose-dependently. These data suggest that reactive oxygen species may be involved in the intimal response to balloon catheter injury, and that antioxidants, such as vitamin E, may offer some protection against restenosis. Although the way by which it does so is unclear, one possible mechanism is by a direct inhibitory effect on the accumulation of smooth muscle cells within the developing neo-intima.