细胞外基质抗干细胞衰老在骨缺损修复中的应用研究

骨缺损修复是困扰临床的一项国际性医学难题，以干细胞（MSCs）为核心的骨组织工程将改变“拆东墙补西墙”的传统治疗模式。但干细胞会因缺损局部缺血、缺氧、炎细胞浸润的恶劣微环境，出现氧化应激性衰老，丧失自我更新并减弱组织修复能力。我们前期研究发现，利用脱细胞技术构建的细胞外基质（ECM）能有效降低炎症环境下干细胞内活性氧的过度累积、增强抗氧化功能并提高MSCs存活率。因此本项目假设“在体外重建ECM微环境，用于保护MSCs免受氧化应激导致的细胞衰老”，拟模拟氧化应激环境，明确ECM各基质成分对延缓干细胞衰老的调控；阐明SIRT1在ECM抗衰老中的作用机制；并在动物模型上验证ECM对骨缺损修复MSCs的抗衰老保护作用。研究成果将有助于阐明干细胞抗衰老的分子机理，提高干细胞修复骨缺损的临床疗效，设计具备精确调控细胞生长微环境、抗衰老功能的组织工程生物材料。

The reconstruction of large bone defects remains a major clinical challenge. Bone tissue engineering using mesenchymal stem cells (MSCs) holds great promise as an effective solution to the drawbacks of traditional bone reconstruction. However, it has been reported that MSCs subjected to oxidative stress may undergo a process of senescence in inflammatory and hypoxic microenvironment of defect site causes. Oxidative stress-induced senescence irreversibly inhibits MSCs proliferative ability, and suppresses their regenerative potentials. We previously reported that decellularized extracellular matrix (ECM) derived from MSCs facilitated large-scale expansion of MSCs in vitro and promoted their lineage specific differentiation. ECM microenvironment significantly decreased the intracellular accumulation of ROS in MSCs, significantly improved stem cell survival and antioxidant activity during oxidative stress. Hence, we propose that the reconstruction of the in vitro microenvironment could protect MSCs from oxidative stress-induced senescence. In the present study, we will utilize H2O2 to establish an oxidative stress environment and analyze the anti-senescence effects of ECM stromal components on MSCs. Also, we will focus on the critical role of SIRT1 in anti-senescence effects of ECM and further explore the underlying mechanisms. The repair of bone defects with MSCs will be further verified via rat model. It is anticipated that this study will help decipher the molecular mechanisms underlying anti-senescence effects of ECM, improve the effects of stem cell for repairing bone defects, and produce precise patterning of suitable scaffold for tissue engineering.