ABSTRACT
BACKGROUND: Cigarette smoking is a major risk factor for the development of cardiovascular disease. However, in terms of the vessel wall, the underlying pathomechanisms of cigarette smoking are incompletely understood, partly due to a lack of adequate in vivo models. METHODS: Apolipoprotein E-deficient mice were exposed to filtered air (sham) or to cigarette mainstream smoke at a total particulate matter (TPM) concentration of 600 microg/l for 1, 2, 3, or 4 h, for 5 days/week. After exposure for 10 +/- 1 weeks, arterial thrombosis and neointima formation at the carotid artery were induced using 10% ferric chloride. RESULTS: Mice exposed to mainstream smoke exhibited shortened time to thrombotic occlusion (p < 0.01) and lower vascular patency rates (p < 0.001). Morphometric and immunohistochemical analysis of neointimal lesions demonstrated that mainstream smoke exposure increased the amount of alpha-actin-positive smooth muscle cells (p < 0.05) and dose-dependently increased the intima-to-media ratio (p < 0.05). Additional analysis of smooth muscle cells in vitro suggested that 10 microg TPM/ml increased cell proliferation without affecting viability or apoptosis, whereas higher concentrations (100 and 500 microg TPM/ml) appeared to be cytotoxic. CONCLUSIONS: Taken together, these findings suggest that cigarette smoking promotes arterial thrombosis and modulates the size and composition of neointimal lesions after arterial injury in apolipoprotein E-deficient mice.
