靶向AMPK延缓干细胞衰老防治老年骨质疏松症的研究

The cell senescence and related imbalance between osteogenesis and adipogenesis of bone marrow mesenchymal stem cells (MSC) are the major pathological factors in age-related osteoporosis. Low-grade age-related systemic inflammation have also been reported to accelerate the senescence of stem cells. Several reports and our previous results have indicated that the cellular energy homeostasis could affect the cells senescence and stem cells differentiation. This study is designed to find if the adenosine 5‘-monophosphate (AMP)-activated protein kinase (AMPK), an intracellular energy sensor, could be targeted to regulate the osteogenesis or adipogenesis of stem cells, as well as to inhibit the cell senescence and inflammation. Firstly, we will compare the stem cells proliferation and differentiation, cell senescence and energy metabolism among MSCs from different age donors. Then the effects of activation or inhibition of AMPK on the cell senescence and differentiation, the cross talk of AMPK gene with inflammatory signaling pathway and longevity genes will be investigated. Finally the nude mice model with ectopic implantation of AMPK over-expressed stem cells and the conditional AMPK gene knock-in transgene mice will be used to evaluate the local bone formation and systemic bone remodeling. We believe that the systemic molecular, cellular and animal study will find if the AMPK activation could prevent the cell senescence and rescue the impaired osteogenic differentiation of stem cell, thus provide a new target for the drug development to treat the age-related osteoporosis.

骨髓间充质干细胞（MSCs）的衰老和成骨成脂分化失衡是老年骨质疏松症发生的重要病理环节，老年人的慢性低炎症状态会加速干细胞的衰老并影响其成骨分化。文献及预实验结果提示，能量代谢是影响细胞衰老和分化的重要调节因素。本研究旨在分析细胞内的能量代谢调节器-腺苷酸活化蛋白激酶 (AMPK)在干细胞成骨成脂分化调节、拮抗衰老和炎症等方面的作用及分子机制。研究内容包括对不同年龄干细胞的增殖分化能力、细胞衰老相关指标以及能量代谢水平的比较，AMPK活化或抑制对老年干细胞衰老和分化的影响研究，AMPK与炎症信号通路及长寿基因等的交互作用研究，MSCs内AMPK过表达裸鼠异位成骨模型研究，MSCs内AMPK条件性激活的转基因动物模型研究，以从分子、细胞和动物水平分析调节AMPK靶向干细胞衰老及分化失衡的作用，为今后老年骨质疏松症的防治和药物开发提供新的分子靶点。

老年性骨质疏松症及其社会经济负担是老龄化社会面临的一大难题，但目前针对该疾病的发病机制和干预靶点的研究尚未成熟。本研究旨在分析腺苷酸活化蛋白激酶（AMPK）信号通路在衰老与炎症环境中对间充质干细胞（MSCs）生物学行为的调控机制并探讨AMPK激酶作为防治老年性骨质疏松症新靶点的潜力。主要研究发现有：（1）通过对比老年小鼠及青年小鼠间充质干细胞生物学功能差异，发现衰老会导致AMPK激活水平显著下调同时伴有间充质干细胞增殖分化能力减弱；（2）在体外特异性激活AMPK信号通路能有效促进衰老间充质干细胞的成骨分化及增殖能力；（3）在构建间充质干细胞特异性AMPK组成型激活小鼠模型的基础上，发现激活AMPK信号通路能显著挽救衰老所引起的小鼠骨量丢失，并能有效降低细胞内活性氧水平，保护间充质干细胞的增殖分化能力。以上研究结果提示，AMPK是间充质干细胞成骨分化和细胞衰老的关键调控因子，未来AMPK信号通路有望成为老年骨质疏松症防治的新干预靶点。