SIRT1对氧化还原状态调控在BMSCs参与种植体骨整合中的作用机制研究

Impaired osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) is related to incomplete osseointegration of dental implants. Stem cells are of different intracellular redox state compared to end-stage cells. We found decreased SIRT1 expression in osteoblasts differentiated from BMSCs, but the interaction between SIRT1 and intracellular redox states and the effects from which on osteogenic differentiation of BMSCs is still illusive. In this proposed schedule, dynamic oscillation of intracellular redox states and corresponding SIRT1 expression in the progress of osteogenic differentiation of BMSCs will be studied. Osteogenic differentiation efficiencies of BMSCs challenged by various intra- and extra-cellular redox states and the related regulation mechanisms of SIRT1 will be explored. Using diabetes and periodontitis animal models to mimic the implanting environment of oxidation stress, we will also carry out the dental implanting experiment under different perturbations through various modes, which can affect the redox states of the microevironment around the implants. Osseointegration efficiencies will be evaluated from different aspects to ascertain functional activities of BMSCs and SIRT1 regulation or response. The results will help us to formulate a recipe to improve osseointegration efficiency in oxidation stress environment by redox state intervention through proper manners at proper time points. The final aim of the plan is to providing an applicable solution to promote osseointegration efficiency for individuals with oxidation stress implanting microenvironment, such as those of diabetes.

骨髓间充质干细胞(BMSCs)骨向分化受抑与种植牙骨整合失败密切相关。干细胞和终末细胞具有不同的胞内氧化还原状态。我们发现SIRT1在BMSCs骨向分化后表达程度降低，但是氧化还原状态与SIRT1相互关系在BMSCs骨向分化和骨整合中的作用机制尚不清楚。本项目将阐明BMSCs骨向分化过程中，细胞内氧化还原状态和SIRT1表达的动态变化规律；揭示胞内、外氧化还原状态改变对BMSCs骨向分化影响及胞内SIRT1的调控作用；利用糖尿病和牙周炎动物模型模拟高氧化应激种植环境，以不同方式干预种植微环境的氧化还原状态，评价BMSCs参与的骨整合效果及SIRT1的作用，建立通过适时、适当干预种植体局部微环境氧化还原状态的方法，提高牙种植体骨整合效率的方法，以期为提高诸如糖尿病等高氧化应激状态患者种植体骨整合效果提供证据支持。

干细胞骨向分化受抑与种植牙骨整合失败密切相关。干细胞和终末细胞具有不同的胞内氧化还原状态。我们发现SIRT1在干细胞骨向分化后表达程度降低，但是氧化还原状态与SIRT1相互关系在干细胞骨向分化和骨整合中的作用机制尚不清楚。本项目主要研究了干细胞在氧化应激状态下细胞增殖、成骨能力和氧化应激水平的变化；SIRT1激活剂白藜芦醇对于氧化应激状态下细胞增殖、成骨、氧化应激水平的影响；SIRT1在调控氧化应激状态下细胞增殖、骨向分化、氧化还原状态的作用机制。研究选用糖尿病新西兰大白兔作为高氧化应激状态动物模型，在牙种植手术同时给予还原型谷胱甘肽局部干预，观察还原剂对于高氧化应激状态下种植体骨整合的影响。体内实验进一步选用比格犬大动物进行下颌骨内种植手术，在种植手术同期给予SIRT1激活剂白藜芦醇局部干预，通过显微CT及硬组织切片观察种植体骨整合效果。. 细胞实验结果证实氧化应激状态下细胞增殖、成骨能力显著下降，氧化应激水平显著升高；SIRT1激活剂白藜芦醇能够显著增强氧化应激状态下细胞增殖、成骨能力，氧化应激水平下降；在氧化应激状态下细胞内SIRT1表达水平显著下降，但能被SIRT1激活剂白藜芦醇上调、抑制剂EX527下调；调节氧化应激状态下细胞内SIRT1表达水平，细胞增殖、成骨能力显著改变，氧化还原状态随之变化。动物实验结果表明在高氧化应激状态下种植体周围新骨生成能力降低，通过局部给予还原型谷胱甘肽以及白藜芦醇，均能显著提高高氧化还原状态下种植体周围成骨能力。证实了改变局部氧化还原状态能够显著提高种植体骨整合效果。本研究通过体内外实验明确了干细胞成骨分化过程中，SIRT1表达、细胞氧化还原状态变化及微环境氧化还原状态对干细胞骨向分化能力的影响；证明了通过干预组织微环境氧化还原状态能有效提高种植体骨整合效果。本研究为提高诸如糖尿病等高氧化应激状态患者种植体骨整合提供新的治疗策略。