Establishment of neural stem cell transplantaion for spinal cord injury

成年哺乳动物中枢神经系统损伤的恢复受到其有限的能力，以取代失去的细胞和受损的髓鞘，并重建功能性神经连接。然而，近年来干细胞生物学的进展使得使用几种细胞来源治疗脊髓损伤成为可能，例如胚胎干细胞、间充质干细胞和神经干细胞。首先，我们将来自胎鼠脊髓的体外扩增的神经干/祖细胞移植到颈中段挫伤后9天的脊髓中，导致熟练前肢运动的功能恢复。然而，啮齿类动物和灵长类动物的脊髓解剖结构和功能有很大的不同，这表明利用灵长类动物建立脊髓损伤的临床前模型以开展细胞治疗的必要性。 关于我们 移植体外扩增的人胚胎脊髓神经干/祖细胞。人神经干/祖细胞移植到灵长类动物脊髓损伤后9天存活，分化为神经元、星形胶质细胞和少突胶质细胞，并最终促进灵长类动物脊髓损伤后运动功能的恢复。最后，为了实现受损轴突的进一步再生，我们开发了轴突生长抑制剂之一Sema 3A的阻断剂，并且我们在体外显示该试剂对Sema 3A对神经突延伸的化学排斥活性以及对生长锥的塌陷活性具有阻断作用。并通过大鼠脊髓损伤模型的实验验证了该阻断剂的有效性。在诱导成年S-D大鼠Th 8水平脊髓横断损伤后，通过渗透泵将阻断剂或赋形剂注入损伤的脊髓。在治疗组中，与溶剂对照组相比，后肢运动显著恢复，并且在其尾部部位以及损伤部位观察到GAP-43阳性纤维，这在溶剂对照中未观察到。这些结果表明，阻断Sema 3A是一种潜在的治疗脊髓损伤的药物，尽管目前仍有许多问题没有解决，如支架和如何克服胶质瘢痕的形成，阻止受损轴突的再生，我们的研究结果强烈表明，神经干/祖细胞移植作为人类脊髓损伤的治疗的可行性。少

Recovery from central nervous system damage in adult mammals is hindered by their limited ability to replace lost cells and damaged myelin, and reestablish functional neural connections. However, recent progresses in stem cell biology are making it feasible to treat spinal cord injury using several cell sources, such as embryonic stem cells, mesenchymal stem cells, and neural stem cells.First, we transplanted in vitro expanded neural stem/progenitor cells, derived from fetal rat spinal cord into the spinal cord 9 days after contusion injury at the middle of the cervical level, resulting in the functional recovery of skilled forelimb movement. However, it should be noted that the anatomy and function of spinal cord are quite different between rodents and primates, indicating the necessity of pre-clinical model of spinal cord injury using primate animals to develop the cell therapy.Secondary, we established a primate model of the spinal cord contusion injury, using a common marmoset and … More transplanted in vitro expanded human neural stem/progenitor cells derived from fetal spinal cord. The human neural stem/progenitor cells grafted into primate spinal cord 9 days after injury survived, differentiated into neurons, astrocytes, and oligodendrocytes, and eventually promoted the recovery of motor function after spinal cord injury in primate animals.Finally, to achieve further regeneration of the damaged axon, we developed the blocking agent to Sema 3A, which is one of the axonal growth inhibitors, and we showed that this agent has a blocking effect against Sema 3A chemorepulsive activity to neurite extension as well as collapse activity to growth cone in vitro. Then we demonstrated the validity of this blocking agent to the rat SCI model. After inducing spinal cord transection injury at Th 8 level in adult S-D rats, we infused the blocking agent or vehicle into the injured spinal cord through an osmotic pump. In the treated group, hindlimb movement was recovered significantly compared to the vehicle-control group, and moreover, GAP-43 positive fibers were observed in its caudal site as well as injured site, which was not observed in the vehicle controls. These findings suggest that blocking of Sema 3A is a potential therapeutic reagent for SCI.Although there are many problems still unresolved such as scaffold and how to overcome the glial scar formation that prevents the regeneration of injured axons, our findings strongly suggest the feasibility of transplantation neural stem/progenitor cells as therapeutics of human spinal cord injury. Less