CELLULAR AND MOLECULAR STRATEGIES IN SPINAL CORD REPAIR

脊髓损伤的破坏性影响是由于神经元的死亡和幸存神经元的轴突在损伤所产生的不适宜环境中再生的失败。 拟议的实验将测试新的细胞和分子修复策略是否会促进再生，导致运动和感觉恢复在成年大鼠脊髓损伤的良好特征模型。在初步研究中，我们已经制备了神经营养因子的逆转录病毒和重组腺病毒构建体，并表明经遗传修饰表达BDNF的成纤维细胞的椎管内移植促进红核脊髓轴突的再生，有助于运动恢复。 我们还使用了质粒构建体和重组腺病毒的椎管内注射，以管理基因脊髓和脊髓上神经元，可以提高他们的生存和再生后轴突切断。 在本实验中，我们将使用从胚胎大鼠脊髓中分离的多潜能神经干细胞作为移植物。 这些细胞是非常有前途的，因为它们具有自我更新、分化成神经元和神经胶质以及遗传修饰的能力。 我们将对这些细胞进行遗传修饰，使其表达神经营养因子BDNF和NT 3或粘附蛋白L1，并通过质粒注射或腺病毒递送抗凋亡基因Bcl-2。 我们建议，这种组合的治疗将提高神经元的存活和轴突再生，并促进运动和感觉功能的恢复，通过定量测试测量。 在第一系列的实验中，我们将测试的想法，工程神经干细胞移植到单侧颈椎半切病变将与受伤的主机和供应的因素，将拯救轴突切断脊髓和脊髓上神经元，促进其轴突的再生和增强恢复。 在第二系列的实验中，我们将测试的想法，最好的策略，联合治疗将刺激脊髓横断后的下行通路的再生和后肢功能的恢复，在人类完全脊髓损伤的模型中，解剖和行为研究的结果是明确的。 这些实验的结果将有助于开发一种有效的策略，促进神经元存活和轴突再生，这将增强脊髓损伤后的功能恢复。

The devastating effects of spinal cord injury are due to the death of neurons and to the failure of the axons of surviving neurons to regenerate through the inhospitable environment created by the injury. The proposed experiments will test whether novel cellular and molecular strategies of repair will promote regeneration leading to locomotor and sensory recovery in well-characterized models of spinal cord injury in adult rats. In preliminary studies we have prepared retrovirus and recombinant adenovirus constructs of neurotrophins and shown that intraspinal transplants of fibroblasts genetically modified to express BDNF promote regeneration of rubrospinal axons that contribute to locomotor recovery. We have also used intraspinal injections of plasmid constructs and recombinant adenovirus to administer genes to spinal and supraspinal neurons that can enhance their survival and regeneration after axotomy. In the present experiments we will use as transplants multipotential neural stem cells isolated from embryonic rat spinal cord. These cells are very promising because of their capacities for self- renewal, differentiation into neurons and glia and genetic modification. We will genetically modify these cells to express neurotrophin factors BDNF and NT3 or adhesion protein L1, and in addition deliver the antiapoptotic gene Bcl-2 by plasmid injections or adenovirus. We propose that this combination of treatments will enhance neuron survival and axon regeneration and promote the recovery of locomotor and sensory function as measured by quantitative tests. In the first series of experiments we will test the idea that engineered neural stem cells transplanted into a unilateral cervical hemisection lesion will integrate with the injured host and supply factors that will rescue axotomized spinal and supraspinal neurons, promote regeneration of their axons and enhance recovery. In the second series of experiments we will test the idea that the best strategy of combined treatments will stimulate regeneration of descending pathways and recovery of hindlimb function after spinal cord transection, a model for complete spinal cord injury in humans in which results of anatomical and behavioral studies are unambiguous. The results of these experiments will contribute to developing an effective strategy for promoting neuron survival and axon regeneration that will enhance functional recovery after spinal cord injury.