负载PTHrP诱导干细胞源性外泌体的负泊松比钛支架修复骨质疏松性骨缺损的效果和机制研究

骨质疏松性骨缺损修复是临床治疗的难题，骨修复材料的力学适配性、生物活性和抗骨质疏松性是解决问题的关键。前期研究发现甲状旁腺激素相关蛋白类似物（PTHrP）可刺激间充质干细胞旁分泌富含miRNA的外泌体（PTHrP-Exo），促进血管化骨再生，修复骨质疏松性骨缺损。本项目拟将PTHrP-Exo引入负泊松比钛支架，构建兼具力学适配和血管化骨再生性的骨修复材料。首先，优化具有最佳生物活性外泌体的富集方式，通过RNA测序和生物信息学明确其促进血管化骨再生的关键miRNA及作用机制；其次，利用3D打印制备具有力学适配性的负泊松比钛支架，优化电化学工艺参数，在界面构建晶体形貌可控的硅-羟基磷灰石涂层（Si-HA），再通过化学键性结合负载最佳生物活性外泌体，分别从体内外研究该材料在促进骨质疏松来源的细胞成血管和成骨分化，以及骨质疏松性骨缺损修复中的作用，为临床骨质疏松性骨缺损的修复提供材料基础。

Osteoporotic bone defect repair remains a challenge in the clinical treatment, the mechanical adaptability, bioactivity, and anti-osteoporosis ability are critical requirements for bone repair materials. Previously, parathyroid hormone-related protein analogues (PTHrP) was discovered to stimulate mesenchymal stem cells to produce miRNA-rich exosomes (PTHrP-Exo) through paracrine pathways, which can enhance vascularized bone regeneration and repair osteoporotic bone defects. This study aimed to construct an auxetic titanium scaffold coated with PTHrP-Exo, which have good mechanical adaptability and vascularized bone regenerative activity. Firstly, we will optimize the enrichment method of exosomes with the best biological activity, and clarify the mechanism of the key miRNA to promote vascularized bone regeneration by the method of RNA sequencing and bioinformatics. Secondly, the auxetic titanium scaffold with mechanical adaptability will be constructed with the use of 3D printing technique. In addition, we will construct controllably bioactive hydroxyapatite and silicon micro-nano structure coating on the interface of the titanium scaffold. The bioactive PTHrP-Exo will be also load on the interface through chemical bonding. This constructed bioactive titanium scaffold will be studied regarding the promotion of the angiogenesis and osteogenic differentiation of osteoporotic-derived cells and the repair of osteoporotic bone defects. With the feedback from in vitro and vivo experiments, we hope to optimize the material fabrication process to the clinical osteoporotic bone defect repair.