Rho‐kinase and myosin II activities are required for cell type and environment specific migration

Cell migration is important in the development of atherosclerotic lesions. Macrophages and smooth muscle cells migrate into the subendothelial space of arteries, leading to plaque formation. Long‐term inhibition of the activity of Rho‐kinase induces a regression of atherosclerotic coronary lesions, probably by preventing migration of macrophages and smooth muscle cells. Previous reports concerning the effect of Rho‐kinase inhibitors on cell migration are contradictory, however. We examined here the cell type specificity of Rho‐kinase inhibitors and found that migration of endothelial cells, macrophages, and smooth muscle cells was inhibited by treatment with Rho‐kinase inhibitors in a dose‐dependent fashion in a three‐dimensional migration assay, whereas that of fibroblasts and epithelial cells was not inhibited. Myosin II inhibitor prevented cell migration in a manner similar to Rho‐kinase inhibitors. In contrast, in a two‐dimensional migration assay, cell migration was not inhibited by Rho‐kinase or myosin II inhibitors for any of the cell types examined. Taken together, these results indicate that Rho‐kinase inhibitors suppress migration of specific cell types under specific conditions through the regulation of myosin II activity. Our findings suggest that Rho‐kinase is the therapeutic target of atherosclerosis accompanied with invasion by leukocytes and smooth muscle cells.