MCP-1 induces VSMC migration. (A) The confluent VSMC monolayers were wounded by scraping and treated with indicated concentration of MCP-1 or PDGF in serum-free medium. Cell migration to the wound surface was monitored from 0 to 36 hours. The migrated distance of the wound edge was quantitated (n = 3) (bottom panel). Bar represents 200 μm. (B) Chemotaxis assay was carried out with transwell culture chambers. Growth medium containing 10 ng/mL MCP-1 or PDGF was added to the lower wells of the chambers, and 2 × 10⁴ VSMCs were seeded into the upper wells. After 20 hours, the cells migrating to the lower surface of the membrane were examined (original magnification ×100). Five different areas of migrated cells were counted for each data point (n = 5) (right panel). The asterisk indicates a significant difference (**P < .01, ***P < .001). Error bars indicate SD.