基于“齿为骨之余”理论探索补肾中药调控SDF-1/CXCR4参与骨髓间充质干细胞归巢及成骨分化的效应机制

Traditional Chinese medicine(TCM) believes that kidney governs bone to produce marrow and teeth are the rest of bone. It means the breeding, growing, strengthening, declining of teeth and bone are based on whether the source of kidney essence being filling or not. The homing effect of bone marrow mesenchymal stem cells (BMSCs) regulated by SDF-1/CXCR4 biological axis is the premise of osteogenic substitution. Therefore, in the condition of kidney deficiency and tonifying the kidney, the difference of bone mass between tooth and bone and its mechanism are worthy of further study. In this study, lumbar vertebrae and alveolar bone of ovariectomized rats will be selected to compare mechanism of kidney deficiency and tonifying kidney respectively. On the one hand, MicroCT, immunohistochemistry and other molecular biological techniques will be used to explain the difference of "teeth-bone correlation" from the experimental level in rats, that is, the bone mass ratio of lumbar vertebrae to alveolar bone. On the other hand, this study will explore that kidney-tonifying TCM can regulate the biological axis of SDF-1/CXCR4, promote the directional homing ability of endogenous BMSCs, regenerate and repair the "tooth-bone" defect site, so as to play the role of osteogenic differentiation. And verify the theory of traditional Chinese medicine from the reverse. This study will explore the mechanism of kidney-tonifying traditional Chinese medicine regulating SDF-1/CXCR4 involved in homing and osteogenic differentiation of bone marrow mesenchymal stem cells based on the theory -teeth being the rest of bone, and provide biological reference for kidney-tonifying TCM in the treatment of osteoporosis.

中医理论认为，“肾主骨生髓”且“齿为骨之余”，齿与骨的生、长、强、槁都本于肾精之源的充盈与否。骨髓间充质干细胞(BMSCs)通过生物体内SDF-1/CXCR4生物轴调控发生的归巢效应是发挥成骨替代作用的前提。在肾虚和补肾双态下，腰椎骨（骨）和牙槽骨（齿）的骨量变化差异及其机制值得深入研究。本课题选取去卵巢骨质疏松症(OP)大鼠模型的腰椎骨（骨）和牙槽骨（齿）分别在肾虚和补肾双态下开展效应机制对比研究。一、利用MicroCT和免疫组化等分子生物学技术手段，对去卵巢OP大鼠进行体内实验，观察双态下腰椎骨与牙槽骨的骨量，揭示两部位在双态下的骨量差异；二、通过补肾中药调控SDF-1/CXCR4生物轴，增强内源性BMSCs归巢能力，促进成骨分化，反推验证中医理论。本课题将为“齿为骨之余”中医理论的科学内涵提供生物学依据，为补肾中药治疗OP提供生物学参考依据。

项目背景：既往研究表明，绝经后骨质疏松症患者牙槽骨骨密度显著降低，且可能伴随渐进性骨破坏以及牙槽骨高度丧失的病理性改变。基础研究也提示，去卵巢骨质疏松大鼠下颌关节及软骨骨密度降低。据此，本研究聚焦去卵巢骨质疏松症(OP)大鼠模型，分别选取腰椎骨（骨）和下颌骨（齿），开展肾虚和补肾双态下的效应机制对比研究，旨在为“肾主骨生髓”、“齿为骨之余”等中医理论在骨质疏松症（OP）治疗中提供生物学依据。主要研究内容：本研究选取去卵巢OP大鼠模型，以腰椎骨和下颌骨为研究对象，比较其在肾虚和补肾双态下的骨量差异，并探究其中的机制。同时，通过补肾中药调控SDF-1/CXCR4生物轴，增强内源性BMSCs归巢能力，促进成骨分化，以验证中医理论。重要结果：实验结果显示，在肾虚状态下，去卵巢OP大鼠腰椎骨和下颌骨的骨密度明显下降，BV/TV值显著降低，骨小梁数量明显减少，骨小梁分离度明显增加，表明肾虚可能是造成骨质疏松的重要因素。而在补肾状态下，去卵巢OP大鼠腰椎骨和下颌骨的骨密度均有所增加，其余各骨形态学指标也有相应的变化，提示补肾中成药强骨胶囊对于提高骨量、缓解骨丢失具有重要作用。进一步基于免疫组化等技术研究表明，SDF-1/CXCR4生物轴在调控BMSCs成骨分化中发挥着重要作用。在肾虚状态下，去卵巢OP大鼠腰椎、下颌骨SDF-1表达均显著升高，在补肾中药干预后显著下调。以上结果表明补肾中药强骨胶囊对去卵巢大鼠骨质疏松症的治疗机制可能是通过其介导SDF-1/CXCR4生物轴，增强骨髓间充质干细胞归巢能力，并提高去卵巢OP大鼠OCN、OPN等成骨标志物，从而促进骨形成。科学意义：本研究的结果为“齿为骨之余”中医理论提供了生物学依据，并为补肾中药治疗OP提供了的参考依据和新的思路。