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| Background: Though the mechanisms of skeletal muscle regeneration are deeply understood, those involved in muscle contusion, one of the most common muscle injuries in sports medicine clinics, are not. Methods: In this study, a total of seventy-two mice were used. Eight of them were randomly chosen for the control group (n=8), while the rest were subjected to muscle contusion. Subsequently, their gastrocnemius muscles were harvested at different time points and the gene expression was analyzed by real-time PCR. Results: The data showed that the expression of many genes, i.e. specific markers of immune cells and satellite cells, regulatory factors for muscle regeneration, cytokines, and chemokines, increased in the early stages of recovery, especially in the first three days. Furthermore, there were strict rules in the expression of these genes. Conclusion: These data suggest that the sequence of immune cells invaded after muscle contusion was neutrophils, M1 macrophages and M2 macrophages. Some CC (CCL2, CCL3 and CCL4) and CXC (CXCL10) chemokines may be involved in the chemotaxis of these immune cells. HGF may be the primary factor to activate the satellite cells after muscle contusion. In addition, intense inflammatory response and regeneration existed simultaneously, suggesting that there were no strict boundaries between the first and second stages of regeneration. Almost all indexes returned to normal at 14d post-injury, meaning that 2 weeks is needed to recover when acute contusion happens, as used in this study. |
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| Keywords:skeletal muscle; contusion; gene; macrophages; satellite cells; cytokines; chemokines |
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