The Roles of Matrix Metalloproteinase 7 in Spinal Cord Ischemia- Reperfusion Injury in Rats

Abstract Background: Neuronal survival after spinal cord ischemia-reperfusion injury (SCII) is a major factor affecting the motor function. Recently, matrix metalloproteinase-7 (MMP-7) plays an important role in a variety of diseases, but the specific role of MMP-7 in SCII remains unclear. This paper aims to further investigate the role of MMP7 in SCII.Methods: We built the SCII model by clipping the aortic arch for 14 minutes. The RNA and protein expression of MMP-7 was detected by Western blot and real-time polymerase chain reaction (PCR) during the groups. The co-localization of major cell types and MMP-7 in the spinal cords was detected by Immunofluorescence staining. To further study the specific mechanism, rats were intrathecally pretreated with si-MMP7 or negative control (NC) siRNA 3 days before clipping the aortic arch for 14 minutes. The Tarlov criteria and Haematoxylin and eosin staining were used to detect neurological function and histological assessment. Western blot, PCR and Immunofluorescence staining were used to evaluate the effect of silencing MMP-7.Results: The expression of MMP-7 RNA and protein increased both at 12 h and 24 h after SCII. At 24 h after SCII, the expression of MMP-7 RNA reached its maximum amount. Compared with the sham group, MMP-7 fluorescent expression in the SCII group greatly enhanced, and MMP-7 fluorescence was mainly co-expressed with neuronal nuclei (NeuN) fluorescence. The Tarlov scores and number of intact neurons were increased by pre-treatment with si-MMP7. Pre-treatment with si-MMP7 could also decrease the expression of MMP-7, Interleukin-1β (IL-1β) and cleaved caspase-3 and reduce the MMP-7 expression in neurons. Conclusions: Silencing MMP-7 protected the rats against SCII by inhibiting the neuroapoptosis and inflammation. Silencing MMP-7 could be a hopeful therapeutic treatment after SCII.