Effects of hyperbaric oxygen on MMP-2 and MMP-9 expression and spinal cord edema after spinal cord injury

Abstract

AimsTo evaluate the effects of hyperbaric oxygen (HBO) therapy on MMP-2 and MMP-9 expression and spinal cord edema after acute spinal cord injury (SCI). Main methodsNinety-six healthy adult Sprague−Dawley rats were randomly divided into 4 groups: sham, sham+HBO, SCI, and SCI+HBO. Each group was subdivided into 4 subgroups of 6 rats each: 24h, 48h, 72h, and 5 d post-injury. The expression levels of matrix metalloproteinase-2 (MMP-2), MMP-9, interleukin (IL-6), and vascular endothelial growth factor (VEGF) were measured using ELISA. The water content of the spinal cord was also measured by Elliot equation. Key findingMMP-2 and MMP-9 levels and spinal cord water content increased significantly in the SCI group compared to those in the sham and sham+HBO groups at different time points after SCI (P<0.01). The MMP-2 level was significantly different between the SCI and SCI+HBO groups at 72h after SCI (P<0.05), while the MMP-9 level was significantly different at 48h, 72h, and 5 d (P<0.05). The water content of the spinal cord was significantly higher in the SCI group at 5 d after SCI (P<0. 01). MMP-2 (P<0.05) and MMP-9 (P<0.01) levels were positively correlated with spinal cord water content. SignificanceHBO reduced SCI-induced spinal cord edema, stabilized the blood–spinal cord barrier, and promoted recovery of neuronal function by down regulating the expression of IL-6, MMP-2, and MMP-9 and up regulating the expression of VEGF.