| Objective To study the effect of subregional tissue-engineered conduits addition with NT-3 on repairing T8 complete transection injury in rat spinal cord.Methods The subregional tissue-engineered conduits addition with NT-3 and polyglycollic acid fibers (PGA) were implanted in T8 spinal cord lesions immediately following 5-mm segment transection in adult rats. All animals were divided into five groups according to the requirement. Regeneration of injuried spinal cord was evaluated by functional assessment, motor evoked potentials (MEPs), electron microscpies, light microscpies and magnetic resonance imaging analysis.Results Proximal and distal stumps of lesion-control group were wrapped in connective tissue. Conduits implanted in spinal cord lesions could bridge the spinal gaps to a certain extent. Functional assessment showed the recovery of hind limb function, and the scores at 2 weeks, 12 weeks of the NT-3 groups were higher than those of other groups (p<0.05). MEPs were evoked by electrical stimulation of the motor cortex or lower injured thoracic levels through needle electrodes inserted subcutaneously. The amplitude and the latency period were recorded from the gastrocnemius muscle in the NT-3 groups. The amplitude of the motor cortex MEPs was higher in the conduit/PGA+NT-3 group compared with that in the NT-3 group (p<0.05). And the latency period of lower injured thoracic levels MEPs in the conduit/PGA+NT-3 group was shorter than that of other groups (p<0.05). Immunohistochemistry-stained sections in the NT-3 groups showed the regenerated nerve fibers in the center of conduits. The nerve fibers growed orderly and did not twist with each other. Luxol fast blue-stained sections in the conduit/PGA+NT-3 group showed the regenerated nerve fibers in the center of conduits, which also growed orderly and did not twist with each other. Electron microscopy alaysis revealed that a number of myelinated axons were present in the conduits. Self-made coils and clinical 3.0T magnetic resonance scanner were applied to observe the repair of T8 complete transection injury directly in rat spinal cord in vivo.Conclusions Conduits implanted in spinal cord lesions could bridge the spinal gaps to a certain extent. Functional assessment showed the recovery of hind limb function, and the scores of the NT-3 groups were better than other groups. MEPs were recorded from the gastrocnemius muscle by electrical stimulation of the motor cortex or lower injuried thoracic levels, which revealed electrophysiological recovery to some extend. The subregional tissue engineered conduit prevented the regenerated nerve fibers from winding to each other to some extent and served as a directional guide for them. The regenerated nerve fibers in subregional tissue engineered conduit/PGA+NT-3 group could grow faster and the conduits established the path way of motor function contact to the distal stumps. The treatment protocol could open potential avenues for repairing spinal cord injury. Self-made coils and clinical magnetic resonance scanner were applied to observe the repair of T8 complete transection injury directly in rat spinal cord in vivo. |
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