Neuroskeletal crosstalk in load-induced bone formation

项目概要/摘要 在人类和临床前模型中，外周神经功能障碍与骨骼脆弱性相关。 虽然本体感觉缺陷在骨折风险增加中起重要作用，但局部神经支配的丧失可能 消耗骨骼中对骨骼稳态至关重要的神经因子。这对维护 神经病变患者和接受神经修饰治疗的患者的骨骼健康。具体而言，它可能 影响负重运动的治疗效果。通过运动对骨骼施加机械负荷是一种 对骨骼健康的明确要求。长骨的压缩导致骨骼重塑， 增强实力。此外，骨细胞在负荷后分泌神经营养因子， 向骨骼发芽，改变内源性骨骼神经支配模式。考虑到这种新兴的 神经在骨骼代谢中的作用，可能需要局部神经骨骼信号传导来促进负荷诱导的骨骼代谢。 骨形成这项建议的中心目标是研究神经骨骼的可塑性和必要性， 骨对压缩载荷的合成代谢反应中的串扰。为了实现这一目标，拟议的研究 分为两个目标。在目标1中，新的神经骨骼龛参与负荷诱导骨形成将是 定义了为了研究骨骼适应过程中天然神经骨骼龛是如何改变的， 将对小鼠进行体内轴向压缩方案以诱导板层骨形成，然后 胫骨的组织学和成像。将使用新的泛神经元Baf 53 b-Ai 9映射骨中的神经 报告小鼠和神经亚型的免疫染色。此外，局部Ngf和Wnt 1基因表达将 使用原位杂交，与确定的神经骨骼小生境相关。研究空间 轴突的定位和相对数量，矿化表面和基因表达，一种新的图像分析 将使用工作流（RadialQuant）。在目标2中，这些神经骨骼小生境对于负荷诱导的 评价骨形成。为了测试这一点，将通过评估开发胫骨去神经支配模型 使用成像技术进行股骨和/或坐骨神经切除术一周后的神经元丢失， 目标1.为了测试骨骼适应中神经支配的必要性，将相应地切断后肢的神经支配 在目标1中的循环轴向压缩之前。目标1中的技术将用于隔离负载的影响 和去神经对轴突密度、矿物质沉积和基因表达的影响。长期职业目标 申请人将经营一个独立的研究实验室。除了研究计划，培训计划是 旨在通过发展新的技术技能，指导和关键的综合来实现这一目标。 文学这项为期两年的研究将在华盛顿大学医学院进行， 埃里卡舍勒博士和马修席尔瓦博士的指导，具有神经骨骼生物学和骨骼方面的专业知识 生物力学，分别。

PROJECT SUMMARY/ABSTRACT Peripheral nerve dysfunction is associated with skeletal fragility in humans and in preclinical models. While proprioceptive deficits play a significant role in increased fracture risk, loss of local innervation may deplete bone of neuronal factors critical for skeletal homeostasis. This presents new challenges for maintaining bone health in patients with neuropathy and those undergoing nerve-modifying treatments. Specifically, it may affect the therapeutic efficacy of weight-bearing exercise. Mechanically loading bone through exercise is a well-established requirement for bone health. Compression of long bones results in skeletal remodeling to increase strength. In addition, bone cells secrete neurotrophic cues after loading that may facilitate nerve sprouting towards the skeleton, modifying endogenous skeletal innervation patterns. Considering this emerging role of nerves in skeletal metabolism, local neuroskeletal signaling may be required to facilitate load-induced bone formation. The central goal of this proposal is to investigate the plasticity and necessity of neuroskeletal crosstalk in the anabolic response of bone to compressive loading. To accomplish this, the proposed research is divided into two aims. In Aim 1, novel neuroskeletal niches involved in load-induced bone formation will be defined. To investigate how native neuroskeletal niches are modified during skeletal adaptation, a 5-day regimen of in vivo axial compression will be conducted on mice to induce lamellar bone formation, followed by histology and imaging of the tibia. Nerves in bone will be mapped using a novel pan-neuronal Baf53b-Ai9 reporter mouse and immunostaining for nerve subtypes. In addition, local Ngf and Wnt1 gene expression will be mapped in relation to defined neuroskeletal niches using in situ hybridization. To study the spatial localization and relative quantities of axons, mineralizing surface, and gene expression, a novel image analysis workflow (RadialQuant) will be used. In Aim 2, the necessity of these neuroskeletal niches for load-induced bone formation will be evaluated. To test this, a model of tibial denervation will be developed by evaluating neuronal loss after one-week of femoral and/or sciatic neurectomy using the imaging techniques employed in Aim 1. To test the necessity of innervation in skeletal adaptation, the hindlimb will be denervated accordingly prior to cyclic axial compression as in Aim 1. Techniques from Aim 1 will be used isolate the effect of loading and denervation on axon density, mineral apposition, and gene expression. The long-term career goal of the applicant is to run an independent research laboratory. In addition to the research plan, the training plan is designed to achieve this goal through development of new technical skills, mentorship, and critical synthesis of literature. The two-year fellowship will be conducted at the Washington University School of Medicine under the mentorship of Dr. Erica Scheller and Dr. Matthew Silva, with expertise in neuroskeletal biology and bone biomechanics, respectively.