Knockdown of MicroRNA-21 Promotes Neurological Recovery After Acute Spinal Cord Injury

To assess the therapeutic effects of microRNA-21 (miR-21) knockdown (KD) for acute thoracic spinal cord contusion using a mouse model. Forty C57/BL6 mice were randomly divided into four groups: mice in the sham-operated (Sham) group received surgical procedure without spinal cord contusion; the spinal cord injury (SCI) group mice underwent spinal cord contusion without treatment; mice in the miR-21 KD group underwent spinal cord contusion followed by a single dose subdural injection of miR-21 KD vectors (1 × 10 7 TU); and the negative control (NC) group mice were given subdural injection of comparable amount of NC vectors (1 × 10 7 TU) after spinal cord contusion. The Basso Mouse Scale (BMS) was employed to assess hindlimb motor functions. Hematoxylin–eosin and Luxol fast blue staining were performed to evaluate pathologic changes in spinal cord tissues. Peripheral blood serum levels of tumor necrosis factor α (TNFα), transforming growth factor β (TGF-β) and interleukin-1β (IL-1β) were determined by the enzyme-linked immunosorbent assay, and mRNA expression of Brain derived neurotrophic factor (BDNF) was examined by reverse transcription-polymerase chain reaction (RT-PCR). Western blotting was performed to analyze the AKT signaling pathway. KD of miRNA-21 effectively improved the BMS scores at day 14 post-surgery compared with the SCI group ( p