The correlationship between MMP-9 expression and the blood-spinal cord barrier disruption in chronic compressive cervical myelopathy

Objective To investigate the correlation between the expression of MMP-9 and the disruption of the blood spinal cord barrier (BSCB) in chronic cervical cord compressive myelopathy rat model. Methods 48 adult rats were randomly divided into group A (sham surgical group, n=24) and group B (spinal cord compressive group, n=24). A water-absorbing polymer sheet was implanted into the C5 epidural space on the posterolateral side to induce a chronic spinal cord compression model. BBB scores and SEP were collected 4 weeks after surgery. Expression of MMP-9 and endothelial barrier antigen (EBA) were detected immunohistochemically in different spinal cord areas of 12 rats in each group. The other 12 rats were performed with Evans blue (EB) perfusion to observe the permeability of BSCB. The results and the correlation between MMP-9 and EBA expression were analyzed. Results BBB score was lower in spinal cord compressive group than that of sham surgical group. Latency was delayed and amplitude was reduced significantly in spinal cord compressive group. Expression level of MMP-9 in spinal cord compressive group was significant higher than that in both grey matter and white matter in sham surgical group. In the contrary, EBA expression was obviously more in grey matter of sham surgical group than that in spinal cord compressive group, while it showed no significant change in white matter between the 2 groups. EB perfusion in sham surgical group was less than that in spinal cord compressive group. MMP-9 expression was correlated with EBA staining significantly. Conclusion Neurological function of spinal cord in the compression group was abnormal, with a marked decline 4 weeks after model made. The increased permeability and structural failure of BSCB in chronic spinal cord compression myelopathy, which was characterized and correlated with increment of MMP-9 expression and decrement of EBA expression concurrently. Disruption of BSCB may be correlated with distinct increasing expression of MMP-9. Key words: Spinal cord compression; Rats; Matrix metalloproteinase 9