miR-210修饰的BMMSCs来源外泌体复合可注射水凝胶激活PI3K/Akt通路治疗激素性股骨头坏死

Steroid-induced osteonecrosis of the femoral head is a disabling disease that results from interruption of blood supply to the bone. The mechanism is poorly understood, but femoral head ischemia finally results in the death of marrow and osteocytes, femoral head collapse and symptomatic hip arthritis. The key point in the treatment of such patients is improving blood supply and bone reconstruction. Our previous study found that hypoxia preconditioned BMMSCs protects against osteonecrosis of the femoral head through exosomes secretion. It was found that miR-210 play a role in promoting cell proliferation and neovascularization by activating PI3K/Akt pathway. We have demonstrated that chitosan-based hydrogel possessed the characteristic of injectability, thermosensitivity and sustained release and that combination of nano-hydroxyapatite(nHA) with polymer improves the osteogenic activity. This project is a continuation of previous research. First of all, the effects of exosomes derived from miR-210 modified BMMSCs on PI3K/Akt pathway and downstream target gene of angiogenesis and osteogenesis were investigated. Secondly, injectable and thermosensitive nHA/chitosan(CS)/sodium alginate(SA) hydrogel was prepared by the incorporatin of nHA into the CS/SA hydrogel and loaded with exosomes derived from miR-210 modified BMMSCs, The biomechanical properties and bioactivities of the materials were assessed. Finally, the hydrogel materials were implanted into the femoral head, and the characteristics of angiogenesis and osteogenesis were evaluated. The project may provide a new strategy for the treatment of osteonecrosis of the femoral head.

激素性股骨头坏死是一种高致残率疾病，改善血供促进坏死区骨修复重建是其治疗的关键。我们前期研究发现低氧预处理的干细胞主要通过外泌体来发挥治疗效应，预实验发现miR-210通过激活PI3K/Akt通路促进BMMSCs增殖和血管新生。课题组已证实基于壳聚糖的复合水凝胶具有可注射、温敏、缓释的仿生特性，棒状纳米羟基磷灰石(nHA)可进一步提高多聚物的成骨活性。本项目是既往研究的继续，拟通过提取miR-210修饰的BMMSCs来源外泌体，观察其对PI3K/Akt通路及下游成骨、成血管相关基因的影响；其次将棒状nHA引入壳聚糖(CS)/海藻酸钠(SA)凝胶制备出新型可注射成骨活性nHA/CS/SA水凝胶，并搭载miR-210修饰的BMMSCs来源外泌体，检测该复合凝胶支架的生物学和力学特性；最后通过动物实验验证这一复合支架的成血管和成骨修复性能，为早中期股骨头坏死的治疗提供新的策略。

激素性股骨头坏死为进展性的难治性疾病，给患者带来极大的痛苦，已成为非创伤性股骨头坏死的主要原因，其发病机制尚未完全阐明，目前尚无一种理想的治疗方法。我们前期研究发现低氧预处理的干细胞主要通过外泌体来发挥治疗效应。本项目成功提取miR-210修饰的BMMSCs及miR-378修饰的ADSCs来源外泌体，发现其可通过激活PI3K/Akt和Shh信号通路，促进BMMSCs增殖及成骨分化，增强HUVECs迁移、成血管能力，具有促进成血管成骨偶联作用，对大鼠激素性股骨头坏死发挥预防及保护作用。课题组成功合成棒状Li-nHA与季胺化壳聚糖(QCS)、双醛基化聚乙二醇（DF-PEG）制备出新型可注射成骨QCSB/PEG/Li-HA水凝胶，具备良好的生物学和缓释特性，并搭载miR-378修饰的BMMSCs来源外泌体，对股骨头坏死具有修复作用。本研究的顺利完成为临床预防、治疗股骨头坏死及其机制的阐明提供一种新方法。