Sema3A-Nrp-1介导的神经调控在颅脑损伤骨折加速愈合中作用及机制研究

The promoting effect of traumatic brain injury on fracture healing has been vandicatied, while its mechanism remains unclear. Illumination of this machanism is of great significance for clinical treatment of delayed union and nonunion. Recent research showed that the innervation of nerve fiber in callus plays a pivotal role in fracture healing, and semaphorin3A, an axon guidance molecule may regulate bone metabolism by affecting sensory nerve innervation. Our previous studies showed that the expression of Sema 3A in serum significantly increased and was associated with the damage degree of brain injury in fracture models combined with TBI. These results suggest that semaphorin3A may be the key joint connecting central nerve repairment with expedited fracture healing..Thereby here we plan to address the issue that: (1) Whether sema3A, combining with its receptor NRP-1 affect the process of bone union through regulating the sensory nerve innervation within the fracture zone? (2) By which means does nerve innervation impart fracture healing? Whether Sema 3A promotes union by facilitating osteoblasts differentiation? (3) whether the canon Wnt/β-catenin pathway, which regulates osteoblasts differentiation as well as proliferation is involved in the way Sema 3A function? Answers to the questions above may provide a new target or concept in dealing with fracture non-union and delay union.

颅脑损伤促进骨折愈合的现象已经被证实，然而其机制及相关信号通路仍未阐述清楚，认识这一机制对临床治疗骨折延迟愈合、骨折不愈合等一系列临床难症有重要意义。最新研究表明，骨折愈合与神经纤维长入骨痂密切相关，神经生长导向因子Sema 3A，可通过调控感觉神经纤维长入调节骨量代谢。我们前期研究结果发现：颅脑损伤后血清Sema 3A表达明显增高，且与颅脑损伤严重程度成正相关。提示：Sema 3A可能是连接中枢神经修复和骨折加速愈合之间的桥梁。.在此基础上，提出本课题设计：⑴颅脑损伤时Sema 3A及其受体Nrp-1是否通过调控骨折局部感觉神经纤维长入而影响骨折愈合进程？⑵其作用途径什么？是否通过促进成骨细胞分化促进成骨加速呢？⑶调控成骨细胞的分化、增殖的经典Wnt/β-catenin信号通路与这一途径的关系？以期阐明颅脑损伤促进骨折加速愈合的机制，为骨折不愈合及延迟愈合治疗提供新的思路及作用靶点。

项目背景：颅脑损伤患者骨折愈合加速是临床常见现象，然而其机制并不清楚。前人研究发现Sema3A作为神经导向因子具有调节骨量代谢的作用。我们前期研究结果发现：颅脑损伤后患者血清Sema3A表达增高，由此猜想Sema3A可能为颅脑损伤促进骨折加速愈合的重要分子。.研究内容：本课题进行了以下研究：1）合并颅脑损伤股骨骨折鼠模型的制作和评价； 2）分析损伤后体内Sema3a变化趋势；3）收集骨痂标本，探究骨痂处神经生长分布情况；4）探究Sema3A与其受体Nrp-1结合后对成骨细胞、破骨细胞增殖能力的影响、对破骨细胞分化能力的影响；5）Sema3A刺激破骨细胞后分泌miRNA的表达差异；6）探究sema3A对破骨细胞内蛋白表达的影响。.实验结果及意义：本研究证实sema3a与其受体Nrp-1结合后能够介导颅脑损伤后骨折加速愈合。我们的研究发现，sema3a对于成骨细胞的直接刺激作用并非主要机制，其加速骨折愈合的机制主要通过促进骨折局部神经纤维长入以及抑制破骨细胞分化。具体表现为抑制细胞内miR-133，miR-214，miR-487三种miRNA的表达，同时影响参与Wnt16a信号通路的关键蛋白，即PSMB9从而促进骨折愈合。发现Sema3A是促进骨折愈合的重要靶点，认识Sema3A参与调节的信号通路为临床治疗骨折延迟愈合、骨折不愈合等一系列临床难症提供潜在靶点，具有重要意义。以上研究结果，发表 SCI 论文 2 篇，在投 SCI 1 篇，中文核心期刊论文 2 篇，申请实用新型专利 1 项。