可控型DFO-PLGA/多孔镁支架激活HIF-1α通路修复骨缺损的促血管和骨生成效应

The development of synthetic scaffolds for application in bone defect repair, which combine optimum properties such as pore architecture, mechanical strength, bioactivity and controllable degradation rate, represents a significant challenge to current regenerative medical research. Until now there have been few synthetic scaffolds that could combine these properties, which has severely limited their application for bone regeneration, especially large size bone defects. In this study, a well controllable DFO-PLGA/Mg scaffold,which may meet the upper requirements, will be designed and fabricated by the method of TWSH and microcapsule technology. This project aims to investigate the relationships between scaffold composition and biodegradation rate, making the corrosion rate of the scaffold match the bone defect repair; investigate the relationships between pore morphologies and mechanical properties, accurately controlling the pore morphologies and simultaneously obtaining the appropriate mechanical properties; evaluate the osteogenesis and angiogenesis effects of DFO-PLGA/Mg scaffold, especially the specific mechanism on HIF-1α signaling pathway. This study will provide a new way to develop an ideal bone tissue replacement materials.

理想的骨缺损修复支架材料应具有必需的多孔结构、适当的生物降解速率、良好的力学性能以及成骨诱导能力。但目前为止，很少有支架能够同时具备以上特征。鉴于此，本项目利用一种全新的方法 — 钛丝造孔法（Titanium wire space holder，TWSH），并结合微球载药技术，构建可控型DFO-PLGA/多孔镁支架，以期能够满足骨缺损修复的条件。本研究旨在探究支架降解速率与构成组分的关系，使支架的降解速率与骨修复再生速率相匹配；构建多孔结构与力学强度的关系模型，实现多孔结构与力学结构的平衡可控；探讨DFO（去铁胺）与多孔镁支架结合后的协同成骨和成血管效应，并进一步探究其对HIF-1α通路的具体影响机制。该项目的研究,为骨缺损再生修复支架的设计提供新思路。

理想的骨缺损修复支架材料应具有必需的多孔结构、适当的生物降解速率、良好的力学性能以及成骨诱导能力。但目前为止，很少有支架能够同时具备以上特征。本研究中，在多孔镁的基础上，引入Nd 和 Zn元素，通过钛丝造孔（Tantalum wire space holder，TWSH）法制备出多孔Mg-Nd-Zn (P-MNZ) 支架。体外浸没及电化学实验结果表明稀土元素Nd 和 Zn的引入明显提高了其抗腐蚀性能。细胞活性，细胞骨架观察，ALP活性及成骨相关基因表达等体外实验结果表明，P-MNZ支架具有良好的生物相容性和促进成骨细胞分化及矿化的能力；Micro-CT观察 , Van Gieson 染色和序贯荧光标记结果等体内实验结果也进一步证明了Nd 和 Zn的引入明显提高了多空镁支架的抗腐蚀性能以及促成骨作用。与此同时，为了进一步提高多孔镁支架的成骨及成血管作用，本课题利用聚乳酸聚乙醇酸共聚物（PLGA）作为微球载体，制备DFO(去铁胺)-PLGA微球颗粒，将DFO-PLGA微球颗粒有效的载入到P-MNZ的多孔结构中，构建出了可生物降解性DFO-PLGA/多孔镁（DFO-PMNZ）支架。体外实验结果表明，DFO-PLGA的引入进一步促进了成骨细胞的粘附、伸展、增殖、分化和矿化作用，这些作用的增强可能与DFO阻碍了HIF-1α的降解有关；体内实验结果表明， DFO-PMNZ降解部位的新骨体积，骨小梁的数量和厚度都明显高于P-MNZ，证明了DFO的引入能够进一步提高P-MNZ支架的骨生成作用。总之，该项目的研究,为骨缺损再生可降解修复支架的设计提供了新的思路。