MicroRNA-223 expression in neutrophils in the early phase of secondary damage after spinal cord injury

►MicroRNA-223 after spinal cord injury in mouse showed high levels of expression. ► The signals of miR-223 in epicenter merged with Gr-1 positive neutrophils. ► Inflammatory cytokines also showed high levels of expression in epicenter. ► MicroRNA-223 might regulate neutrophils in the early phase after spinal cord injury. MicroRNA (miR)s are short non-coding RNAs that suppress the translation of target genes, and play an important role in gene regulation. Despite this prominence, there are few reports that refer to the expression of miRs after spinal cord injury (SCI). Previously, we reported on miR-223 expression after SCI in mice. The purpose of this study is to reveal the distribution of miR-223 and identify the cells that express miR-223 in the injured spinal cord. Quantitative polymerase chain reaction analysis revealed high expression of miR-223 at 12 h after SCI. Double staining of in situ hybridization and immunohistochemistry showed that the signals of miR-223 merged with Gr-1 positive neutrophils. Our data indicate that miR-223 might regulate neutrophils in the early phase after SCI.