去铁敏修饰复合孔径静电纺丝支架构建及修复临界尺寸骨缺损作用机理研究

Tissue engineering provides a promising method for the repair of critical-sized bone defect, a difficult problem facing modern medicine. Studies showed that angiogenesis and functionalization were crucial for grafts to improve the therapeutic effects of grafts. On the basis of biodegradable microbubbles and electrospinning scaffolds, we plan to: i) prepare drug-release polyester microbubbles with deferoxamine inside, using polyester, by rapid emulsion film technology, and examining the sizes of microbubbles, drug-loading amount, drug-loading rate and so on; ii) manufacture porous composite scaffold by electrospinning and laser techniques, modify the scaffold with deferoxamine-loaded microbubbles, and evaluating the biological, physical and chemical properties; iii) construct critical-sized bone defect animal model, evaluate the angiogenesis and functionalization properties of the scaffold by Micro-CT, mechanics and other methods. All together, we hope to improve the construction method and obtain the electrospinning scaffold with sustained drug-release and bionic porous composite structure. The successful construction of the tissue scaffold could reveal the mechanisms of angiogenesis and functionalization in the repair of critical-sized bone defect, verify the rule of functionalization, and provide new materials, technique and strategy for treatment of critical-sized bone defect, and offer novel data accumulation and theoretical basis for tissue engineering.

临界尺寸骨缺损的修复是现代医学面临的棘手难题，组织工程是治疗临界性骨缺损的有效方法。研究表明，移植物难以血管化、功能化是制约其修复效果的关键所在。本项目在前期研制生物可降解微泡及静电纺丝支架基础上，①通过化学方法，设计合成具备适宜生物及理化性质的可降解聚内酯材料，采用快速乳化膜技术，制备核层包裹去铁敏的缓释载药微泡，检测微泡粒径、载药量、载药率等；②采用湿法静电纺丝结合激光致孔技术制备具有仿生复合孔径静电纺丝组织工程支架，在支架中引入去铁敏载药微泡进行修饰，评价生物学性能及理化性质；③构建临界尺寸骨缺损动物模型，通过Micro-CT、骨密度检查、力学测试等评价支架的血管化及功能化性能，得到具有持续药物控释、仿生复合孔径的静电纺丝支架。揭示支架血管化对临界尺寸骨缺损的修复机理，验证功能化规律，最终为临界尺寸骨缺损的治疗提供新的材料、技术和策略，为组织工程的进一步实用化积累数据、提供理论基础。

临界尺寸骨缺损的修复是现代医学面临的棘手难题，组织工程是治疗临界性骨缺损的有效方法。研究表明，移植物难以血管化、功能化是制约其修复效果的关键所在。为解决这一难题，课题组在前期研究基础上，采用3D打印技术结合等离子修饰、胶原涂覆、微囊载药等技术，设计和构建了载去铁敏的骨组织工程支架，并进行了促成骨效能验证。制备了3D打印骨组织工程支架，并通过扫描电镜（SEM）、原子力显微镜（AFM）等理化表征测试，确定最佳的支架制备参数；通过快速乳化膜技术，制备了PLGA载药微球，其粒径分布较为均匀，无明显爆发性释放，其缓释性能良好，适合用于载药；制备了载去铁敏修饰的3D打印PLA骨组织工程支架，并进行了体外和体内实验验证：体外实验证明，支架具有良好的细胞相容性及细胞黏附性能；茜素红实验表明载药支架可诱导MC3T3-E1细胞成骨分化；qPCR显示其成骨基因ALP、RUNX2和OCN表达增强；构建了兔桡骨临界尺寸骨缺损模型用于体内实验；所制备的骨组织工程支架无明显肝肾及组织学毒性；X线显示载药支架植入后12周时可见缺损周围形成高亮条带状影且与骨折断端相连接，基本实现内外侧皮质骨相连。本项目的顺利实施，为临界尺寸骨缺损的修复与治疗提供了新的思路和方法。