Objective To study the regulatory roles of macrophages and smooth muscle cells in lesion formation induced by polyethylene cuff placement.Methods C57BL/6 mice(8～10 weeks of age) were used to establish vascular injury model.A nonconstrictive cuff was placed around the right femoral artery.To block the receptor tyrosine kinase signal pathway,monoclonal antibody AFS98 against macrophage-colony stimulating factor receptor c-fms or antibody APB5 against platelet-derived growth factor receptor-β was administered.After another 2 weeks,both right and left femoral arteries were taken and subjected to histochemical analysis.Results In the mice that had not received either antibody,a large number of macrophages and smooth muscle cells were detected in the right femoral artery,whereas such cells was not observed in the sham-operated left artery.In the right artery from the mice given AFS98,the cell density recognized by anti-macrophage antibody BM8 was markedly reduced.In striking contrast,the mice given APB5 showed an increase in the number of macrophages and a relative decrease in SMC density in the right artery.Conclusion There are numerous macrophages and smooth muscle cells aggregated in the femoral artery injuried by cuff placement in mice.Macrophages and smooth muscle cells may play opposite roles in the lesion formation.