Background—Neovascularization within the intima of human atherosclerotic lesions is well described, but its role in the progression of atherosclerosis is unknown. In this report, we first demonstrate that intimal vessels occur in advanced lesions of apolipoprotein E–deficient (apoE −/−) mice. To test the hypothesis that intimal vessels promote atherosclerosis, we investigated the effect of angiogenesis inhibitors on plaque growth in apoE −/− mice.

Methods and Results—ApoE −/− mice were fed a 0.15% cholesterol diet. At age 20 weeks, mice were divided into 3 groups and treated for 16 weeks as follows: group 1, recombinant mouse endostatin, 20 mg · kg⁻¹ · d⁻¹; group 2, fumagillin analogue TNP-470, 30 mg/kg every other day; and group 3, control animals that received a similar volume of buffer. Average cholesterol levels were similar in all groups. Plaque areas were quantified at the aortic origin. Median plaque area before treatment was 0.250 mm² (range, 0.170 to 0.348; n=10). Median plaque areas were 0.321 (0.238 to 0.412; n=10), 0.402 (0.248 to 0.533; n=15), and 0.751 mm² (0.503 to 0.838; n=12) for the endostatin, TNP-470, and control groups, respectively (P≤0.0001). Therefore, endostatin and TNP-470 inhibited plaque growth during the treatment period by 85% and 70%. Intimal smooth muscle cell contents of plaques from control and treated mice were similar.

Conclusions—Prolonged treatment with either angiogenesis inhibitor reduced plaque growth and intimal neovascularization in apoE −/− mice. Although the mechanism of plaque inhibition induced by these agents is not established, these results suggest that intimal neovascularization may promote plaque development.