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 以皮质脊髓运动系统为靶点，自主运动控制的最重要途径 人类。在过去四年的一系列研究中，我们发现皮质脊髓束(CST)轴突 小鼠、大鼠脊髓损伤部位再生为脊髓神经干细胞(NSC)移植 猴子。这些再生的CST轴突与移植物形成突触，移植物又延伸到非常长的距离 大量新的轴突从损伤部位远距离进入脊髓远端。神经 因此形成了跨越损伤的继电器，支持功能改善。这项工作是在一个人身上进行的 翻译路径和支持IND的工作正在进行中。 这项拨款提出了两个新的方向，这两个方向将对支持人工翻译至关重要。 首先，我们最近报道了受损的成年小鼠cst神经元恢复为胚胎转录。 脊髓损伤后持续两周的状态，在此期间CST轴突可以再生。这一发现 建立了小鼠脊髓损伤后支持恢复的关键干预时期。做同样的事 在灵长类动物的大脑中，转录回复到促进生长的胚胎状态？如果是的话，需要多长时间 能持续下去吗？目标1的工作将明确回答这个问题，首次确定什么可能是 支持灵长类动物功能恢复的任何类型的治疗干预的最佳时间窗口， 包括人类。我们将对脊髓损伤后的CST神经元进行特异性RNA测序(RNAseq) 使用交叉病毒方法的恒河猴，基于对猴子的支持性初步数据。 在目标2中，我们首次提出使用新的病毒载体顺行、跨突触追踪 灵长类皮质脊髓向脊髓的投射。我们的初步研究表明，啮齿动物CST 轴突几乎全部投射到脊髓中间神经元，而在灵长类动物中，绝大多数的 CST轴突直接终止于阿尔法运动神经元。了解CST预测的准确目标 脊髓将显著扩展我们对灵长类运动系统组织的基本知识， 并将允许优化干细胞移植的特性，以增强跨神经网络位置的神经中继形成 SCI。与其他治疗脊髓损伤的神经干细胞计划不同，我们的工作旨在直接重建关键神经 通过移植OPC传递严重损伤，而不是目标备用轴突；获得知识 从这个目标出发，可以显著改善灵长类系统中跨损伤部位的接力队形。

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.