EGF-genistein inhibits neointimal hyperplasia after vascular injury in an experimental restenosis model.

A murine model of vascular injury-induced neointimal hyperplasia was developed by using a photoactive dye, rose bengal. Photoactivation of rose bengal induced vascular injury to the femoral arteries of C57B1/6 mice and resulted in an occlusive neointimal hyperplasia after 4 weeks. The cellular elements of the hyperplastic neointima were found to be alpha-actin-positive vascular smooth muscle cells expressing epidermal growth factor (EGF) receptor at high levels. EGF-Gen, an EGF-R-specific inhibitor with potent anticancer activity, suppressed the formation of hyperplastic neointima. Morphometric analysis of serial tissue sections at 4 weeks after vascular injury showed that in 75% of the EGF-Gen-treated mice, the maximal stenosis index was only 0.44 +/- 0.13, whereas in 75% of phosphate-buffered saline (PBS)-treated mice, the maximal stenosis index was 1.20 +/- 0.25. The mean neointima/media ratios for areas of maximum neointimal hyperplasia were 0.59 +/- 0.16 (n = 24) for the EGF-Gen-treated group, 0.99 +/- 16 (n = 45) for the PBS group (EGF-Gen vs. PBS, p = 0.0017), and 1.03 +/- 18 (n = 8) for group treated with unconjugated genistein (EGF-Gen vs. Gen, p = 0.0088). EGF-Gen treatment of mice with vascular injury to the left femoral artery was not associated with any clinical signs of toxicity or histopathologic lesions in any of the organs, including the uninjured right femoral artery. EGF-Gen also inhibited VSMC migration in vitro, without affecting VSMC proliferation and viability, suggesting that EGF-Gen is blocking neointima formation by inhibiting cellular migration to vascular injury sites. In conclusion, EGF-Gen may be useful as a nontoxic prophylactic agent for prevention of restenosis in clinical settings.