ObjectiveTo investigate the regulatory effect of miRNA-21-5p (miR-21) on spinal fibroblasts, and to explore the mechanism of miR-21 related pathological process of spinal cord injury.MethodsSpinal cord fibroblasts were identified by immunofluorescence. Spinal fibroblasts damage model was established by scratch method. Quantitative real-time polymerase chain reaction (RT-PCR) was used to determine the relative expression of miR-21 and fibrosis-related genes in spinal cord fibroblasts after injury. The expression of miR-21 in spinal cord fibroblasts was up-regulated and down-regulated by using miR-21 mimics/inhibitor, and the expression levels of apoptosis and proliferation-related proteins were detected by Western Blot (WB).ResultsThe expression of miR-21 and fibrosis-related genes were increased after spinal cord fibroblast scratch (P<0.05). Up-regulation of the miR-21 can increase the expression of apoptosis-related genes in fibroblasts (P<0.05), and vice versa. The proliferation of fibroblasts was consistent with the expression of miR-21, while the apoptosis of fibroblasts was contrary to the expression of miR-21.ConclusionsmiR-21 enhanced the fibrosis and proliferation, inhibited the apoptosis of spinal cord fibroblasts after mechanical injury. This indicates that miR-21 is closely related with the formation of fibrotic scar after spinal cord injury, which also providesa potential therapeutic target for spinal cord injury.