Characterization of Chronic Contusive Spinal Cord Injury and Promotion of Corticospinal Tract Regeneration

慢性挫伤性脊髓损伤的特点和促进 皮质脊髓束再生 总结 慢性脊髓损伤（SCI）是一个损伤后阶段，当损伤是稳定的，几乎没有额外的 变化虽然绝大多数SCI是慢性的，但很少有研究来描述慢性SCI的特征。 在临床相关动物模型中在组织学、细胞和分子水平上损伤。甚至有 关于慢性SCI治疗方法的研究较少，尤其是促进 脊髓上运动轴突再生，包括最重要的皮质脊髓束（CST）系统 人类重要的自主运动控制系统。因此，我们建议使用慢性临床 相关的中度双侧下颈椎挫伤模型，用于在细胞和分子水平表征 提高熟练手功能的新疗法的水平和开发。 这项建议有三个具体目标。目的1是确定相关的细胞机制 与慢性挫伤性SCI，以指导发现新的分子机制，以促进 再生我们将建立一个中度慢性双侧下（C6）颈椎挫伤模型， 大多数SCI患者（65%）是四肢瘫痪，手部功能丧失， 独立性和生活质量。受伤的大鼠存活长达12个月的SCI慢性阶段 用于表征胶质瘢痕、细胞外分子（ECM）和轴突状态。目标2：识别 与慢性挫伤性SCI相关的转录机制，以指导发现新的 促进再生的分子机制。我们将使用一种新开发的技术 依赖于Cre的Ribotag载体，用于从慢性损伤的组织中分离特异性mRNA， CST神经元用于使用RNAseq表征其转录组。然后我们比较一下 完整和亚急性损伤的CST神经元的转录组（我们已经有了这些数据集）， 慢性损伤的CST神经元再生为神经祖细胞（NPC）移植物，以确定关键 与细胞/轴突生长相关的分子途径被破坏，我们可以治疗靶向 这些分子途径在目标3和未来的研究。目标3是测试候选机制， 促进慢性损伤的CST神经元的恢复，促进轴突再生， 慢性脊髓损伤我们将首先对Aim 2中确定的潜在候选靶点进行体外筛选， 促进出生后皮质神经元和成年背根神经节（DRG）神经元的轴突生长。我们 然后测试这些候选基因，以促进慢性损伤的CST的再生， NPC移植作为一种允许的细胞基质。这项工作的结果将大大 扩展我们对慢性SCI的认识，并开发慢性SCI的潜在治疗方法。

Characterization of Chronic Contusive Spinal Cord Injury and Promotion of Corticospinal Tract Regeneration Summary Chronic spinal cord injury (SCI) is a post-injury stage when the injury is stable with little additional change. Although the vast majority of SCI are chronic, there are few studies to characterize the chronic injury at histological, cellular, and molecular level in clinical relevant animal models. There are even fewer studies for development of therapeutic treatment of chronic SCI, especially for promotion of supraspinal motor axonal regeneration, including the corticospinal tract (CST) system that is the most important voluntary motor control system in humans. Therefore, we propose to use a chronic clinical relevant moderate bilateral lower cervical contusion model for characterization it at cellular and molecular levels and development of new therapies for improvement of skilled hand function. There are three Specific Aims in this proposal. Aim 1 is to identify cellular mechanisms associated with chronic contusive SCI, to guide discovery of new molecular mechanisms to promote regeneration. We will develop a moderate chronic bilateral lower (C6) cervical contusion model since the majority of SCI patients (65%) are quadriplegic, with loss of hand function that is critical for independence and quality of life. The injured rats survive for up to 12 months to a chronic stage of SCI for characterization of glial scar, extra cellular molecules (ECM) and axonal state. Aim 2 is to identify transcriptional mechanisms associated with chronic contusive SCI, to guide discovery of new molecular mechanisms to promote regeneration. We will use a newly developed technique developed in our lab, Cre-dependent Ribotag vectors, to isolate mRNA specific from chronically injured CST neurons for characterization of their transcriptome using RNAseq. We then compare this transcriptome to intact and sub-acutely injured CST neurons (we already have these datasets) and chronically injured CST neurons that regenerate into neural progenitor cell (NPC) graft to identify key molecular pathways related to cellular/axonal growth that are disrupted, We can therapeutically target these molecular pathways in Aim 3 and future studies. Aim 3 is to test candidate mechanisms to promote recovery of chronically injured CST neurons and promote axonal regeneration after chronic SCI. We will first perform in vitro screen for the potential candidate targets identified in Aim2 to promote neurite growth of postnatal cortical neurons and adult dorsal root ganglion (DRG) neurons. We then test these candidate genes to promote regeneration of chronically injured CST in combination with NPC transplants that serve as a permissive cellular substrate. Findings of this work will substantially extend our knowledge of chronic SCI and develop potential treatment for chronic SCI.