Applications of Neural Stem Cells in Spinal Cord Injury

尽管在阐明神经干细胞特性并将其用于移植方面取得了进展，但挑战 中枢神经系统损伤后神经细胞替代的问题仍难以解决。这项提案将使用 移植神经元和胶质细胞限制性前体细胞(NRP/GRP)以重建受损的感觉 急性和慢性脊髓损伤(SCI)后的系统。这些实验的目的是建立神经元 穿过背柱损毁，重新连接失神经背侧柱核(DCN)。这个 该提案涉及与干细胞生物学应用于中枢神经系统损伤相关的重要问题，包括如何 以产生移植物衍生的神经元，引导它们的轴突生长，克服损伤的抑制环境， 最重要的是，如何与失神经的靶点形成功能性突触。我们将继续我们的 通过试验证明NRP/GRP移植的接力形成原理的研究 改善中继器功能方面的假设，并将这一策略推广到慢性脊髓损伤。在AIM 1，我们将测试突触密度和活动诱导可塑性在产生稳定和功能的 DCN靶区的突触连接。我们认为，a)与靶神经元的突触活动将会改善 通过增加突触密度(更多的轴突)对靶部位的诱发电位进行求和 减少DCN周围神经网的抑制，以及b)突触稳定性将随着时间的推移而改善， 特定于任务的活动，并伴随着感官传递的刺激。在目标2中，我们将检验假设 失去神经的目标可以重新连接和重新训练，以正确地解释慢性 伤害期。具体地说，我们将测试a)如何促进宿主感觉神经轴突生长到慢性 伤害，以及b)如何促进目标的连通性，在DCN长期受制的地方 去感觉神经。为了实现慢性损伤的连接，我们将使用神经营养素、软骨素酶 (通过新的病毒载体传递)，以及运动/训练方案。这种接力模型使我们能够超越 当前的重点是再生，发挥神经干细胞产生的胚胎神经元的优势 细胞，并研究在定义明确的系统中恢复连接和改进功能所需的步骤。

Despite progress in elucidating neural stem cell properties and using them for transplantation, the challenges of neuronal cell replacement following CNS injury remain difficult to resolve. This proposal will use transplants of neuronal and glial restricted progenitors (NRP/GRP) to reconnect the disrupted sensory system after acute and chronic spinal cord injury (SCI). The experiments are designed to build neuronal relays across a dorsal column lesion reconnecting the denervated dorsal column nucleus (DCN). The proposal addresses important issues related to application of stem cell biology to CNS injury, including how to generate graft derived neurons, direct their axon growth, overcome the inhibitory environment of the injury, and, most importantiy, how to form functional synapses with the denervated target. We will continue our studies that demonstrated the principles of relay formation with NRP/GRP transplants by testing specific hypotheses for improving the functional aspects of the relay and advance this strategy to chronic SCI. In Aim 1, we will test the role of synaptic density and activity-induced plasticity in producing stable and functional synaptic connections at the DCN target. We propose that a) synaptic activity with target neurons will improve through summation of the evoked potentials at the target site by increasing synaptic density (more axons) and reducing inhibition of perineuronal nets at the DCN, and b) synapse stability will improve with time, with task-specific activity, and with stimulation of the sensory relay. In Aim 2 we will test the hypothesis that denervated targets can be reconnected and retrained to correctly interpret sensory information at a chronic injury stage. Specifically, we will test a) how to promote host sensory axons to grow into the site of a chronic injury, and b) how to promote connectivity at the target, where the DCN has been subject to prolonged deafferentation. To achieve connectivity in the chronic injury, we will use neurotrophins, chondroitinase (delivered by novel viral vectors), and exercise/training protocols. This relay model allows us to go beyond the current focus on regeneration, exploit the advantages of embryonic neurons produced by neural stem cells, and examine the steps needed to restore connectivity and improve function in a well-defined system.