ALK3对骨再生的调控及其促进颌面部骨缺损修复的研究

As a common and important receptor-like protein kinase of BMP2、BMP7, ALK3 plays an essential role during bone development and remodeling. However, its function in bone regeneration and the underlying mechanism are largely unknown. Besides, it is also implied that the combination of ALK3 specific modulation with artificial bone repair material may be an efficient way to enhance its osteoinductive activity and meanwhile avoid the side-effects. This project aims to study the regulatory mechanism and application of ALK3 in bone regeneration based on three different aspects, including "functional analysis", "mechanism research" and "application exploration". First, to analyze the biological function of ALK3 on bone regeneration, mouse models with bone marrow mesenchymal stem cell (BMSC) specific edition of Alk3 will be generated, and the repairment of bone defects in each group will be examined and compared. Second, to explore the undelying mechanism, iTRAQ technology will be employed to screen the downstream signaling pathways and factors what mediated by ALK3, further identification will be analyzed via both in vivo and in vitro experiments. Third, to explore the application of ALK3 in bone reconstruction, the composite hydrogel with osteogenic activity and pH bidirectional responsiveness will be generated using ALK3 specific regulator modified hydrogel, then used for minimally invasive treatment of rabbit cavity jaw defects. Results of this study will not only enhance our understanding about the biological function of ALK3 and the related mechanisms that involved in bone regeneration, but also provide scientific evidences for the subsequent clinical transformation and application.

ALK3作为BMP2、BMP7关键的共性靶受体蛋白激酶，对骨发育、骨改建起重要调控作用，但其在骨再生中的功能及作用机制，目前尚未明确。此外，将ALK3的特异性调控和人工骨修复材料相结合，可能是提高材料成骨活性并规避相关风险的有效途径。本项目依次从“功能分析”、“机制研究”、“应用初探”三方面开展研究：拟通过构建骨髓间充质干细胞（BMSC）特异性不同ALK3活性的小鼠模型，对比各组小鼠骨缺损修复情况，分析ALK3在骨再生不同阶段的相应功能；利用iTRAQ技术筛选并鉴定ALK3所介导的靶信号通路及下游因子，通过体内外实验，检测其生物学调控功能，分析ALK3的具体作用机制；利用ALK3特异性调控多肽进行材料改性，构建pH双向智能响应型复合水凝胶，用于微创治疗兔颌骨腔隙型缺损，综合评估再生修复效果。研究结果不仅可以完善对ALK3生物学功能及骨再生机制的认识，还有望为后续的临床转化应用提供科学依据。

ALK3作为BMP信号通路的关键受体蛋白激酶，对骨发育、骨改建起重要调控作用，但其在骨再生中的功能尚未明确。本项目通过构建骨组织特异性不同ALK3活性的小鼠模型（Alk3-cKO，Alk3-CA），进行骨缺损造模，并在骨修复的不同时期对ALK3活性进行特异性调控,分析ALK3在骨再生不同阶段的功能，证实ALK 3及其下游信号通路是调控骨祖细胞干性的关键，对骨祖细胞增殖、迁移、分化、矿化以及破骨细胞功能等均起重要影响，同时明确了促骨缺损快速修复的最佳ALK3调控方案。利用iTRAQ技术，进行高通量蛋白谱检测分析，证实ALK3通过调控CAV1、CD44从而对细胞的迁移、胞内信号通路转导等方面发挥重要。进一步将ALK3的特异性调控和人工骨修复材料相结合，构建pH响应降解型抗菌性致孔剂和pH响应固化型外部水凝胶支架，并将两者复合，获得pH双向智能响应型复合水凝胶，用于负载特异性调控ALK3的药物THR-123。体外研究表明，该复合水凝胶材料具有良好的缓释作用，负载THR-123后显示出较佳的成骨诱导活性，同时还兼具抗菌活性，利于细胞长入。进一步将负载THR-123的pH双向智能响应型复合水凝胶用于兔颌骨腔隙型缺损的治疗，结果显示该水凝胶可用于微创注射，能够原位成胶、在体致孔，利于缺损部位的血管形成与长入，能有效促进骨缺损的快速再生修复。本项目相关研究结果不仅完善了对ALK3生物学功能及骨再生机制的认识，还为临床实现骨缺损的快速再生修复提供了思路。