Objective To investigate the effects of mechanical injury and stromal cell-derived factor-(SDF-1α) on rat cardiomyocytes proliferation and cytokine expression.Methods Rat cardiomyocytes were cultured followed by mechanical injury by scratching and were treated with 80 μg/L SDF-1α during incubation.The proliferative capacity of cardiomyocytes was assessed by BrdU assay and changes in cell cycles were examined by PI staining and flow cytometry.Immunocytochemistry and Western blot were employed to determine the expression of interleukin (IL)-1α,IL-6 and transforming growth factor (TGF)-β1.Results SDF-1α significantly stimulated the growth of mechanically injured cardiomyocytes and increased the proportion of cells in phase S.Mechanical injury promoted the expression of IL-1α (1 vs 2.53±0.54),IL-6 (1 vs 1.47±0.12) and TGF-β1 (1 vs 1.36±0.09) in cardiomyocytes.The combination of mechanical injury and SDF-1α resulted in up-regulated lL-1α and lL-6 (1 vs 1.47±0.13,1 vs 1.54±0.17) expression yet slightly suppressed TCF-β1 expression(1 vs 0.66±0.13).Conclusion SDF-1α may promote proliferation by increasing the proportion of cells in phase S and augment mechanical injury-induced proinflammatory responses in cardiomyocytes.