Inhibition of the migration of MCP-1 positive cells by icing applied soon after crush injury to rat skeletal muscle

Migration of the macrophages to the injured site soon after the skeletal muscle injury is crucial for subsequent regeneration of the muscle fibers. The Monocyte chemoattractant protein-1 (MCP-1) is important chemokine for regulating migration of the monocytes/macrophages. Earlier reports have discussed that icing applied soon after muscle crush injury retards muscle regeneration through retardation of macrophage migration. The MCP-1 + cells and neutrophils might promote the migration of the macrophages. To test the hypothesis that icing soon after the skeletal muscle injury affects MCP-1 + cells and neutrophils, we examined the effect of icing on MCP1 + cells and neutrophils after crush injury to skeletal muscle in rats. Owing to the icing application for 20 min soon after the injury, accumulation of the macrophages was inhibited until 12 h after injury. Numbers of the neutrophils at 3 h after the injury and the MCP-1 + cells at 6 h and later after the injury in the icing group were significantly lower than those in the non-icing group, suggesting that these phenomena contribute to the retardation of macrophage migration.