抑制LIMK2从而直接特异性地提高成骨细胞的力学敏感性对加速骨改建进程的影响及其分子机制的研究

Bone remodeling is an essential microcosmic process involved in the restoration of many diseases, including bone fracture and bone defects. Current therapies for this kind of diseases have a common shortcoming: The process of bone remodeling lasts too long and new-formed bone can not get enough strength to bear weight and daily activity in a short time. Researches showed that there is a close link between bone remodeling, cell mechanosensitivity of osteoblasts, and actin cytoskeleton reorganization. Also, actin cytoskeleton reorganization is regulated by Limk2/cofilin pathway. Our previous work has established a direct and specific way to upregulate the osteoblasts mechanosensitivity via inhibiting the expression of LIMK2 gene. Based on the above mentioned, we hypothesized that upregulating osteoblasts mechanosensitivity via inhibiting LIMK2 gene can enhancing osteoblasts functional activities and affecting bone multicellular unit (BMU), thus accelerating the bone remodeling. Based on our previous researches, we plan to study the effect of upregulating osteoblasts mechanosensitivity on bone remodeling and its molecular mechanism in vitro and in vivo. For all that, our researches are conducive to develop a way to upregulate the mechanosensitivity of bone cells directly and specificly. Futhermore, our achievements will provide a new insight and a promising therapeutic target for therapies of bone related diseases and shorten the time for clinical therapy.

骨改建是骨折、骨缺损等疾病修复重建过程中必须经历的微观过程，目前这些疾病的治疗方法均存在骨改建时间过长、短期内新生骨组织无法承受外力的缺点。国内外研究提示，骨改建、成骨细胞（OB）力学敏感性与肌动蛋白细胞骨架在力学刺激下的改建有关，该改建由LIMK2/cofilin信号通路调控。课题组前期通过抑制LIMK2基因，已初步探索出直接特异性地上调OB力学敏感性的方法。据此我们提出科学假设：通过抑制LIMK2，可上调OB的力学敏感性，促进其功能活动并影响骨改建单位（BMU），加速骨改建进程，加快上述疾病的修复过程。在前期工作基础上，本项目拟进一步从OB单细胞水平、BMU多细胞水平及动物水平来研究上调OB力学敏感性对加速骨改建进程的影响及分子机制。本项目可为上述疾病的修复重建提供新思路；有助于开发直接特异地上调骨组织细胞力学敏感性的方法，从而发现骨组织疾病治疗的新靶点，有助于缩短疾病的临床治疗时间。

骨改建是骨缺损修复重建中必须经历的过程。现有治疗方法存在改建时间过长、短期新生骨无法承受外力的缺点。研究提示，骨改建与细胞力学敏感性及细胞骨架在力学刺激下的改建有关。本课题拟抑制LIMK2，上调成骨细胞（OB）力学敏感性，从成骨细胞单细胞水平、BMU多细胞水平及动物水平研究上调OB力学敏感性对加速骨改建进程的影响及分子机制，以促进骨缺损修复。.项目开展初期，文献查新示：骨细胞对骨改建起主要调控作用，其对力学刺激的敏感性大于成骨细胞等。故将切入点聚焦于骨细胞，研究抑制LIMK2后对MLO-Y4骨细胞在力学刺激下细胞骨架改建的影响。深入研究，遇到：力学加载设备老化，温控装置缺陷，致实验指标受非特异性因素影响，而国外成熟设备昂贵（5万美金）；细胞骨架瞬时变化明显，而原子力显微镜使用不便，操作耗时等瓶颈问题。.研究推进中，我们关注到，除了骨改建，血管化也是促骨缺损修复的关键因素，新生血管不仅为代谢活动提供氧气和营养物质，也为骨组织矿化提供钙、磷等原材料和成骨前体细胞。据此，我们研究了LPA在偶联成骨与成血管过程中作用。同时，新近研究表明干细胞外泌体也在促细胞生存、成血管等具有强大潜能，遂开展了脂肪间充质干细胞外泌体在骨缺损修复及骨组织疾病的研究。.。

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