Applications of Neural Stem Cells in Spinal Cord Injury

尽管在阐明神经干细胞的特性并将其用于移植方面取得了进展，但挑战仍然存在。 中枢神经系统损伤后的神经细胞替代仍然难以解决。该提案将使用 移植神经元和胶质限制性祖细胞（NRP/GRP）以重新连接受损的感觉神经元 急性和慢性脊髓损伤（SCI）后的系统。这些实验旨在建立神经元 中继跨越背柱损伤重新连接失神经背柱核（DCN）。的 一项提案提出了与干细胞生物学应用于CNS损伤相关的重要问题，包括如何 以产生移植衍生的神经元，指导它们的轴突生长，克服损伤的抑制环境， 最重要的是，如何与失神经靶点形成功能性突触。我们将继续 通过测试特定的NRP/GRP移植物来证明中继形成原理的研究 改善中继功能方面的假设，并将此策略推广到慢性SCI。在Aim中 1，我们将测试突触密度和活动诱导的可塑性在产生稳定和功能性的作用。 DCN目标的突触连接。我们提出a）与靶神经元的突触活动将改善 通过增加突触密度（更多轴突）， 和减少对DCN处神经元周网的抑制，以及B）突触稳定性将随时间而改善， 特定任务的活动，并与刺激的感觉继电器。在目标2中，我们将检验以下假设： 失神经的目标可以重新连接和重新训练，以正确地解释感觉信息， 受伤阶段。具体来说，我们将测试a）如何促进宿主感觉轴突生长到慢性炎症的部位， 损伤，以及B）如何促进靶点的连接，其中DCN已经受长时间的 传入神经阻滞为了在慢性损伤中实现连接，我们将使用神经营养素、软骨素酶 （通过新型病毒载体递送）和运动/训练方案。这种接力模式使我们能够超越 目前的重点是再生，利用胚胎神经干产生神经元的优点 细胞，并检查所需的步骤，以恢复连接和改善功能，在一个定义良好的系统。

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.