Optogenetics to improve hand function after spinal cord injury.

项目摘要/摘要 恢复手和手臂功能是颈髓患者的首要治疗任务 受伤。这项研究的目的是开发和测试一种新的方法来提高手和手臂的恢复 脊髓损伤后的功能。我们建议使用光遗传刺激颈脊髓来治疗这两种疾病 改善功能，并揭示脊髓刺激导致康复的机制。 我们的初步数据显示，在以下情况下，前肢功能都能迅速和几乎完全恢复 临床上切合实际的颈髓挫伤后动物接受光遗传脊髓刺激 受伤。光遗传光刺激可以通过直接激活神经回路和还通过 增加损伤脊髓的血流量。在这里，我们建议比较由此导致的功能恢复 来自光遗传和电脊髓刺激，以及电和光的结合 对不表达光遗传蛋白的幼稚动物的刺激。 我们的实验是由一种新型的多功能电极实现的，它允许光学和电学 对啮齿动物脊髓表面的刺激。这些柔性聚合物电极将是 在目标1中精炼，以向大鼠颈脊髓传递慢性光遗传和硬膜外电刺激。 因此，所有动物在被随机分成治疗组之前将被植入相同的硬件以 允许对目标2中的光遗传刺激和电刺激进行直接比较。 我们将使用我们建立的脊髓挫伤大鼠模型，在那里动物被训练来执行 精确的前肢达到准确量化损伤后的功能恢复。我们的协作团队已经 开发了一种可靠的光遗传蛋白病毒转导方法，使光敏离子通道 在非转基因大鼠颈脊髓神经元中均有表达。在接受为期6周的治疗后 光遗传和硬膜外电刺激，我们将探索每种治疗方法的机制 以延长目标3的前肢功能恢复时间。我们将进行终末电生理检查并记录 由光和电刺激在同一动物身上引起的反应。 我们的初步数据显示，光遗传刺激后轴突生长上调。我们会 使用逆行跨突触追踪和组织学方法对绕过损伤的新回路的形成进行量化。 标记的神经元将与通过光遗传刺激而不是硬膜外刺激激活的神经元共同定位 结合原位杂交和免疫组织化学方法阐明修复机制。 综上所述，我们建议揭示光遗传脊髓刺激导致 脊髓损伤后前肢功能几乎完全恢复。一旦了解，我们希望这些 一种直接启发治疗大脑和脊髓一系列神经创伤的机制。

Project Summary/Abstract Restoration of hand and arm function is the highest treatment priority for people with cervical spinal cord injury. The goal of this research is to develop and test a novel method to improve recovery of hand and arm function after spinal cord injury. We propose to use optogenetic stimulation of the cervical spinal cord to both improve function and to uncover the mechanisms by which spinal cord stimulation leads to recovery. Our preliminary data demonstrate both a rapid and near complete recovery of forelimb function when animals receive optogenetic spinal cord stimulation following a clinically-realistic cervical spinal cord contusion injury. Optogenetic light stimulation may provide benefits by both directly activating neural circuits and also by increase blood flow to the injured spinal cord. Here we propose to compare the functional recovery resulting from optogenetic and electrical spinal cord stimulation, as well as the combination of electrical and light stimulation delivered to naïve animals that do not express optogenetic proteins. Our experiments are enabled by a novel multifunctional electrode that permits both optical and electrical stimulation to be delivered to the surface of the spinal cord in rodents. These flexible polymer electrodes will be refined in Aim 1 to deliver chronic optogenetic and epidural electrical stimulation to the rat cervical spinal cord. Thus all animals will be implanted with identical hardware prior to being randomized into treatment groups to permit a direct comparison between optogenetic and electrical stimulation in Aim 2. We will use our established rat model of spinal contusion injury where animals are trained to perform precision forelimb reaching to accurately quantify recovery of function after injury. Our collaborative team has developed a reliable method of viral transduction of optogenetic proteins such that light-sensitive ion channels are expressed in neurons of the non-transgenic rat cervical spinal cord. Following 6-weeks of treatment with optogenetic and epidural electrical stimulation, we will explore the mechanisms by which each treatment leads to prolonged recovery of forelimb function in Aim 3. We will perform terminal electrophysiology and record the responses evoked by both optical and electrical stimulation in the same animals. Our preliminary data demonstrate an upregulation of axon growth following optogenetic stimulation. We will use retrograde trans-synaptic tracing and histology to quantify new circuit formation bypassing the injury. Labelled neurons will be co-localized with the neurons activated by optogenetic vs. epidural stimulation using combined in-situ hybridization and immunohistochemistry to illuminate mechanisms of recovery. In summary, we propose to uncover the mechanisms by which optogenetic spinal cord stimulation leads to nearly complete recovery of forelimb function following spinal cord injury. Once understood, we expect these mechanism to directly inspire treatments for a range of neurological traumas to the brain and spinal cord.