| ObjectiveTo observe the therapeutic effect of siRNA, which could disturb the expression of PTPσ, for the regeneration of axon after spinal cord injury (SCI) in Wistar rats, we injected lentivirus carrying siRNA locally during the acute period of SCI, and further to explore its repair mechanisms.Methods45female Wistar rats were randomly divided into three groups:blank control group (group A, n=15), empty vector group (group B, n=15), and the lentivirus carrying siRNA group (Group C, n=15). NYU Impactor Model-II device was used to induce SCI animal model at the level of Chest10(T10). Group A was injected saline locally after SCI immediately, Group B accepted local injection of lentivirus without siRNA after SCI, Group C accepted local injection of lentivirus carrying siRNA immediately after SCI. Then the hindlimb function behavior score (Basso, Beattie&Bresnahan locomotor rating scale, BBB scale) was analyzed statistically at the time of24hour,3rd day,5th day,1st week,2nd week,3rd week,4th week,5th week,6th week,7th week,8th week after SCI. The spinal cord tissue was taken to observe the expression of EGFP under a fluorescence microscope at the time of the8w after SCI, and to observe the local glial scar and axonal regeneration through hematoxylin-eosin staining (HE staining) and immunohistochemical staining.ResultsAt the time of24h,3d,5d,1w,2w after SCI, there was no significant difference among BBB scores of the three groups (P>0.05), and the BBB score of group C was significantly higher than the group A and group B at each time point after the3rd week (P<0.05). The BBB scores of all the three groups reach a platform after6w. BBB score of group C increased significantly during the period of2w-6w after SCI, in contrast, the other two groups changed slowly (P<0.05). Lots of Fibrillary Acidic Protein was observed in the gray matter of spinal cord around the syringomyelia under the fluorescence microscope, and there was no significant expression in the proximal and distal spinal cord. The immunohistochemical staining shown that the injury cavities were bigger in the injury area of group A and group B, and lots of astrocytes proliferated arounding the cavities to form glial scar. The corticospinal tracts were disorganized, and only a small amount of nerve tract passes through the injury area. In contrast, spinal cord injury cavities were smaller in size in group C, while there was no significant difference about the density of astrocytes around the cavities between all the groups. Furthermore, the corticospinal tracts arranged tidily in group C, and there were more intact nerve tract pass through the injury area.ConclusionLocal injection of lentivirus carrying siRNA, which can disturb the expression of RPTPa, then block the transduction of inhibiting signal from CSPGs, and can significantly promote the regeneration of axons after spinal cord injury at last. It was also shown that lentivirus was a safe carrier for gene therapy, and could replicate within the spinal cord tissue, meanwhile it do not diffuse to distal parts in the body significantly. |
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