| Objective To study the effect of subregional tissue-engineeredconduits addition with NT-3on repairing T8complete transection injuryin rat spinal cord.Methods The subregional tissue-engineered conduits addition withNT-3and polyglycollic acid fibers (PGA) were implanted in T8spinalcord lesions immediately following5-mm segment transection in adultrats. All animals were divided into five groups according to therequirement. Regeneration of injuried spinal cord was evaluated byfunctional assessment, motor evoked potentials (MEPs), electronmicroscpies, light microscpies and magnetic resonance imaging analysis.Results Proximal and distal stumps of lesion-control group werewrapped in connective tissue. Conduits implanted in spinal cord lesionscould bridge the spinal gaps to a certain extent. Functional assessmentshowed the recovery of hind limb function, and the scores at2weeks,12weeks of the NT-3groups were higher than those of other groups(p<0.05). MEPs were evoked by electrical stimulation of the motor cortexor lower injured thoracic levels through needle electrodes insertedsubcutaneously. The amplitude and the latency period were recorded fromthe gastrocnemius muscle in the NT-3groups. The amplitude of the motorcortex MEPs was higher in the conduit/PGA+NT-3group compared withthat in the NT-3group (p<0.05). And the latency period of lower injured thoracic levels MEPs in the conduit/PGA+NT-3group was shorter thanthat of other groups (p<0.05). Immunohistochemistry-stained sections inthe NT-3groups showed the regenerated nerve fibers in the center ofconduits. The nerve fibers growed orderly and did not twist with eachother. Luxol fast blue-stained sections in the conduit/PGA+NT-3groupshowed the regenerated nerve fibers in the center of conduits, which alsogrowed orderly and did not twist with each other. Electron microscopyalaysis revealed that a number of myelinated axons were present in theconduits. Self-made coils and clinical3.0T magnetic resonance scannerwere applied to observe the repair of T8complete transection injurydirectly in rat spinal cord in vivo.Conclusions Conduits implanted in spinal cord lesions could bridgethe spinal gaps to a certain extent. Functional assessment showed therecovery of hind limb function, and the scores of the NT-3groups werebetter than other groups. MEPs were recorded from the gastrocnemiusmuscle by electrical stimulation of the motor cortex or lower injuriedthoracic levels, which revealed electrophysiological recovery to someextend. The subregional tissue engineered conduit prevented theregenerated nerve fibers from winding to each other to some extent andserved as a directional guide for them. The regenerated nerve fibers insubregional tissue engineered conduit/PGA+NT-3group could growfaster and the conduits established the path way of motor function contactto the distal stumps. The treatment protocol could open potential avenuesfor repairing spinal cord injury. Self-made coils and clinical magneticresonance scanner were applied to observe the repair of T8completetransection injury directly in rat spinal cord in vivo. |
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