Mechanisms of Regeneration: Facial Nerve Injury and Repair

项目摘要/摘要 这项建议提出了一个为期五年的研究职业发展计划，重点是刺猬的研究 (HH)通路信号在面神经损伤反应中的作用。该候选人目前是哈佛大学的助理教授。 斯坦福医学院的耳鼻喉科。概述的提案建立在候选人之前的提案基础上 在世界知名的HH通路信号专家的指导下进行研究和临床经验， 菲尔·比奇博士。拟议的实验和教学工作将为候选人提供一套独特的 使他能够在神经损伤机制方面作为内科科学家过渡到独立的技能 反应和神经纤维化。 面瘫导致患者严重残疾，影响面部功能和整体 生活质量。对于永久性瘫痪的患者，手术是改善面部状况的最有效的治疗方法。 对称性--在某些情况下--恢复部分运动。然而，现有的治疗方法并不完全 恢复正常的面部运动。临床上，受损的面神经会变得纤维化，这可能会阻碍 康复和治疗。尽管这在临床上很重要，但神经纤维化的机制是 人们对此知之甚少。鉴于Hedgehog通路在神经周围发育中的关键作用，我们探索了 小鼠面神经损伤后刺猬反应元件的功能。我们首先证实了他的存在 小鼠面神经内对刺猬有反应的成纤维细胞(Gli1)。面部Gli1成纤维细胞 神经在损伤后显著扩张，构成再生神经的大部分神经外膜。 这些细胞与激活的雪旺细胞和再生轴突密切相关，似乎促进了 损伤后前两周的血管生成。然而，在损伤后10周，Gli1成纤维细胞似乎 在神经内形成纤维组织。根据这些发现，我们假设HH信号促进 损伤后早期神经再生，但在损伤后较晚的时间点转变为促纤维化状态。至 评估这些假说，我们提出了以下目标：1)表征面部HH信号的作用 用强大的遗传和药理学模型描述神经损伤，2)描述面部Gli1细胞的变化 通过下一代测序实现神经再生和纤维化。完成本建议书中的研究 将能够彻底剖析HH信号在面神经损伤中的作用，将这一途径作为一种 创伤后再生和纤维化的中介物，为临床应用提供新的治疗靶点。

Project Summary/Abstract This proposal presents a five-year research career development program focused on the study of Hedgehog (Hh) pathway signaling in facial nerve injury response. The candidate is currently an Assistant Professor of Otolaryngology at the Stanford School of Medicine. The outlined proposal builds on the candidate’s previous research and clinical experience under the supervision of a world-renowned expert in Hh pathway signaling, Dr. Phil Beachy. The proposed experiments and didactic work will position the candidate with a unique set of skills that will enable his transition to independence as a physician scientist in the mechanisms of nerve injury response and nerve fibrosis. Facial paralysis results in significant disability for affected patients, impacting both facial function and overall quality of life. For patients with permanent paralysis, surgery is the most effective treatment to improve facial symmetry and – in some cases – restore partial movement. However, existing treatments do not completely restore normal facial movement. Clinically, the injured facial nerve becomes fibrotic, which can impede recovery and treatment. Despite the clinical importance of this, the mechanism underlying nerve fibrosis is poorly understood. Given the critical role of the hedgehog pathway in perineurial development, we explored the function of hedgehog-responsive elements in the murine facial nerve after injury. We first verified the presence of hedgehog-responsive fibroblasts (Gli1+) within the murine facial nerve. Gli1+ fibroblasts within the facial nerve expand impressively after injury and compose the majority of the perineurium of the regenerating nerve. These cells closely associate with activated Schwann cells and regenerating axons and appear to promote angiogenesis in the first two weeks after injury. By 10 weeks after injury, however, Gli1+ fibroblasts appear to form fibrotic tissue within the nerve. Following on these findings, we hypothesize that Hh signaling promotes early nerve regeneration after injury but transitions to a pro-fibrotic state at later time points after injury. To assess these hypotheses, we propose the following aims: 1) Characterize the role of Hh signaling after facial nerve injury using powerful genetic and pharmacologic models, 2) Describe changes in Gli1+ cells during facial nerve regeneration and fibrosis via Next Generation Sequencing. Completion of the research in this proposal will enable a thorough dissection of the role of Hh signaling in facial nerve injury, vet this pathway as a mediator of both regeneration and fibrosis after injury, and reveal new therapeutic targets for clinical use.