负压状态下AMPK/TSC/mTOR信号轴诱发自噬促进间充质干细胞成骨分化的机制研究

The treatment of bone nonunion remains challenging for orthopedist. Negative pressure wound therapy (NPWT) can promote bone healing, but the mechanisms have not been fully elucidated. Recent studies have found that the osteoblast differentiation of mesenchymal stem cells (MSCs) plays a key role in bone healing. Besides, adenosine monophosphate activated protein kinase (AMPK) and autophagy were both involved in the MSCs osteoblast differentiation. Our preliminary data have shown that the autophagy activity in calluses of nonunion group was lower than bone union group.Whereas, NPWT could promote bone healing on the disease model of rabbit, accompanied by increased expression of autophagy activity. Besides, it was confirmed that induction of AMPK could stimulate osteoblast differentiation and suppress the expression of mTOR in mouse preosteoblasts. Based on these proofs, we propose that the NPWT could activate the AMPK/TSC/mTOR axis, which leads to the promotion of MSCs osteoblast differentiation through activation of autophagy. This research will investigate the relationship among AMPK/TSC/mTOR axis, autophagy and MSCs osteoblast differentiation, and illuminate the mechanisms of NPWT promoting bone healing. The present project will clarify the relationship between AMPK/TSC/mTOR axis, autophagy and osteoblast differentiation of MSCs, demonstrate the mechanism of NPWT promoting fracture healing. This research aims to deepen theoretical understanding for NPWT accelerating bone union, and provide theoretical foundation for NPWT in treatment of bone nonunion.

骨不连的治疗较为棘手，负压创面疗法(NPWT)能促进骨愈合，但其机制尚不明确。研究已证实间充质干细胞(MSCs)成骨分化在骨愈合中起关键作用，腺苷酸活化蛋白激酶(AMPK)、自噬都参与了MSCs的成骨分化过程。项目组前期研究发现，骨不连模型组中的自噬表达水平低于骨折愈合组，而NPWT能促进骨愈合，同时伴有自噬表达水平的增高。AMPK的上调能促进MC3T3-E1细胞的成骨分化及自噬表达水平上调，同时自噬门控蛋白mTOR的表达明显下降。据此，项目组假设：NPWT通过AMPK/TSC/mTOR信号轴激发自噬，从而促进MSCs成骨分化。本研究项目拟从分子、细胞、动物水平阐述AMPK/TSC/mTOR信号轴、自噬及MSCs成骨分化之间的关系，探讨AMPK/TSC/mTOR信号轴及自噬在NPWT促进MSCs成骨分化过程中的作用，从而深化对NPWT促进骨愈合机制的认识，为NPWT治疗骨不连提供理论依据。