| Background: The function repair of spinal cord injury (SCI) is a nut in neuroscience. Though many methods have been attempted in the past decades, including peripheral nerve transplantation, embryonic spinal cord graft, schwann cell transplantation and olfactory ensheathing cell graft and so on. However, all of them can not acquire the satisfactory results. According to the modern views: The lack of regenerative properties of the mammalian CNS, especially in the spinal cord, could be attributable to a combination of factors: including the death of large numbers of the functional cells after SCI, due to the primary injury and the secondary pathophysiologic changes in vivo, such as ischemia, edema, inflammation and so on, which can result in the death of a mass of neurons, astrocytes and oligodendrocytes; the lack of sufficient trophic support; the existence of the myelin-associated inhibitors, including Nogo, myelin-associated glycoprotein(MAG) and oligodendrocyte-myelin glycoprotein (OMgp); and injury-induced glial scars. Just these factors cause the obstacle of the functional regeneration after SCI. NSCs are undifferentiated nervous system cells that are capable of proliferation, repeated subculture, and differentiation into all the major cell types of the adult central nervous system, including neuron, astrocyte and oligodendrocyte. Therefore it may be a promising method for the therapy of SCI to transplant the genetic engineering NSC modified to secrete neurotrophic factors. In our study, we explored the feasibility to construct the genetic engineering rat/human NSCs that were modified by lentivirus to deliver both NT-3 and GFP. Meanwhile, we also explored the feasibility for the therapy of SCI by transplating NSC, genetic engineering NSC modified by lentivirus to secrete NT-3 and directly injecting concentrated lentivirai supernatant in vivo which express both NT-3 and GFP.Attempted to establish a stable cell source that can be used for the repair of spinal cord injury and attempted to provide some valuable clues for the further study of SCI.Methods: In the first part of our experiment, after the rat NSCs were isolated and identified, the rat NSC were genetic modified by Lentivirus to express GFP and rat NT-3; then the transgenic expression was detected by the methods of fluorescence microscope, dorsal root ganglion of fetal rats and Western blot.In the second part of our experiment, after the human NSCs were isolated and identified, the human NSC were genetic modified by Lentivirus to express GFP and rat NT-3; then the transgenic expression was detected by the methods of fluorescence microscope, dorsal root ganglion of fetal rats and slot blot.In the third part of our experiment, following hemisection of spinal cord at the level of Tio was produced in 56 adult Wistar rats that were randomly divided into four groups (n=14), namely three treated groups and one control group. The treated groups were dealed with NSCs, genetic engineering NSCs and concentrated Lentiviral supernatant that carries both GFP and NT-3, respectively. Then used fluorescence microscope to detect the transgenic expression in vivo and the method of BBB to assess the function recovery.Results: ?Constructed the genetic engineering rat and human NSC successfully that expressed both NT-3 and GFP; ?the transplanted cells could survive for long time and migrate for long distances in vivo; ?For the rats that were injected with concentrated Lentiviral supernatant, the stably transgenic expression could be detected in vivo; @The hind-limb function of the three treatment groups had obviously improved.Furthermore, compared with the group NSC and the group lentivirus, the hind-limb function of the group genetic engineering neural stem cell accquired the most obvious improvement.Conclusion: ?It is feasible to construct the genetic engineering rat and human NSC mediated by Lentivirus to express both NT-3 and GFP, which can be applied widely in the basic study and the further clinic application of the spinal cord injury as neural grafts. (2) It all have certain effect for the three methods above to cure spinal cord injury, however, compared with the group NSC and the group lentivirus, the graft of transgenic engineering neural stem cells is a more effective method.Our experimental results showed it is feasible to construct the genetic engineering rat and human NSC mediated by Lentivirus to express both NT-3 and GFP, which can be applied widely in the basic study and the further clinic application of the spinal cord injury as neural grafts. Furthermore, the experimental data also proved that all of the threemethods are effective to cure the SCI, however, compared to the group NSC and the group lentivirus, the graft of transgenic engineering neural stem cells is a more effective method. These data indicated that it may be a preferable strategy for the therapy of SCI to transplant the gentic engineering NSC; we also hope these data could provide some valuable clues for the further study of the therapy for SCI.
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