The Primate Corticospinal Connectome and Transcriptome

项目摘要 促进人类脊髓损伤（SCI）后功能恢复的努力可能需要干预 靶向皮质脊髓运动系统，这是自主运动控制的最重要途径， 人类在过去4年的一系列研究中，我们发现皮质脊髓束（CST）轴突 再生为脊髓神经干细胞（NSC）移植物，移植到小鼠、大鼠和 猴子这些再生的CST轴突与移植物形成突触，而移植物又延伸得非常长。 大量新的轴突从损伤部位长距离进入远端脊髓。神经 从而形成跨越损伤的中继，支持功能改善。这项工作是在一个人身上进行的 翻译路径和IND使能工作正在进行中。 这项资助提出了两个新的方向，这对支持人工翻译至关重要。 首先，我们最近报道，损伤的成年小鼠CST神经元恢复到胚胎转录水平， SCI后持续两周的状态，在此期间CST轴突可以再生。这一发现 建立了一个关键时期的干预后，小鼠脊髓损伤，以支持恢复。做同样的 灵长类动物大脑中是否发生了向促生长胚胎状态的转录逆转？如果是这样， 能持续多久目标1的工作将明确回答这个问题，首次确定什么可能是一个 任何类型的治疗干预以支持灵长类动物的功能恢复的最佳时间窗， 包括人类我们将对SCI后的CST神经元进行特异性RNA测序（RNAseq）， 恒河猴使用交叉病毒的方法，基于支持性的初步数据，在猴子。 在目标2中，我们首次提出使用新型病毒载体顺行地、跨突触地追踪 灵长类皮质脊髓向脊髓的投射。我们的初步研究表明， 轴突几乎完全投射到脊髓中间神经元，而在灵长类动物中， CST轴突直接终止于α运动神经元。了解科技委预测的准确目标， 脊髓将显著扩展我们对灵长类动物运动系统组织的基本知识， 并将允许优化干细胞移植物的性质，以增强跨脑缺血部位的神经中继形成。 SCI.与其他SCI的神经干细胞项目不同，我们的工作旨在直接重建关键的神经干细胞。 通过OPCs的移植，在严重损伤中传递，而不是靶向备用轴突;获得的知识 从这个目的可以显着提高在灵长类动物系统中的损伤部位的中继形成。

Project Summary Efforts to promote recovery of function after human spinal cord injury (SCI) will likely require interventions targeting the corticospinal motor system, the most important pathway for voluntary motor control in humans. In a series of studies over the past 4 years we have found that corticospinal tract (CST) axons regenerate into spinal cord neural stem cell (NSC) grafts placed into sites of SCI in mice, rats and monkeys. These regenerating CST axons form synapses with the graft, and the graft in turn extends very large numbers of new axons from the injury site over long distances into the distal spinal cord. Neural relays across the injury are thereby formed, supporting functional improvement. This work is on a human translational path and IND-enabling work is in progress. This grant proposes two new directions that will be critically important in supporting human translation. First, we recently reported that injured adult mouse CST neurons revert to an embryonic transcriptional state that lasts for two weeks after SCI, a time during which CST axons can regenerate. This finding establishes a critical period for intervention after mouse SCI to support recovery. Does the same transcriptional reversion to a pro-growth embryonic state occur in the primate brain? If so, how long does it last? Work in Aim 1 will definitively answer this question, identifying for the first time what may be an optimal time window for therapeutic intervention of any type to support functional recovery in primates, including humans. We will perform RNA sequencing (RNAseq) specifically of CST neurons after SCI in rhesus monkeys using intersectional viral approaches, based on supportive preliminary data in monkeys. In Aim 2 we propose for the first time using novel viral vectors to anterogradely, trans-synaptically trace primate corticospinal projections to the spinal cord. Our preliminary studies demonstrate that rodent CST axons project nearly entirely to spinal cord interneurons, whereas in primates the vast preponderance of CST axons terminate directly on alpha motor neurons. Knowing the precise targets of CST projections to the spinal cord will both markedly extend our basic knowledge of motor system organization in primates, and will allow optimization of stem cell graft properties to enhance neural relay formation across sites of SCI. Unlike other neural stem cell programs for SCI, our work aims to directly re-form critical neural relays across a severe injury, rather than target spared axons through grafts of OPCs; knowledge gained from this aim could markedly improve relay formation across injury sites in the primate system.