可注射VEGF智能化修饰微孔双网络水凝胶在骨修复中的作用机制研究

Bioactive scaffolds can promote the healing process of extensive periapical bone lesions. The angiogenesis and regeneration of vascular network is the basis of bone repair, which is hard to approach. The hydrogel material has been widely used in tissue engineering, however, the low strength and the cell "edge flourish" phenomenon, that is, the cells are easy to develop and perform activities at the edge rather than enrich inside the hydrogel material, limited the application of hydrogel scaffold material. This study is to further optimize the structure, improve the strength of hydrogel material and retain its injectability and self-repair ability based on GC/OHC-PEG-CHO and its block copolymer/calcium alginate double-network hydrogel. The gelatin microspheres were used as porogen to form microcavities in the hydrogel material, and strengthen the "edge flourish phenomenon" around the microcavities to achieve the cell enrichment inside hydrogel material. Furthermore, the VECs cell enrichment region was modified by VEGF to promote hydrogel internal vascularization. This study will explore the effect of VEGF gelatin microspheres on hydrogel composition and network structure，the regulation mechanism of cell behavior and function in hydrogel by VEGF-targeted microcavities, and the effects and mechanism of VEGF-targeted intelligent modified microcavity hydrogel on VECs growth and vascularization in vivo. This study will contribute to the development of hydrogel material and benefit the bone repair and regeneration with hydrogel scaffold materials via early and rapid vascularization.

生物活性支架材料能够促进根尖周大范围骨病损的再生修复进程。支架材料内部有效构建血管网络是骨修复基础，也是制约材料发展的难点。目前水凝胶支架材料强度低，且细胞易于在水凝胶外围富集生长，即“边缘发展”。围绕这个关键科学与技术问题，本项目以GC/OHC-PEG-CHO及其嵌段共聚物/海藻酸钙双网络水凝胶为基础，进一步优化结构，提高水凝胶材料强度，并保留其可注射与自修复能力；以明胶微球作为致孔剂，在水凝胶材料内部构建微孔，人为引入“凝胶微孔边缘现象”，实现水凝胶内部细胞富集生长；以VEGF靶向智能化修饰VECs细胞富集区，促进水凝胶内部血管化。本项目将重点探索载VEGF明胶微球对水凝胶组成及网络架构的影响，VEGF靶向智能化修饰微孔对水凝胶中细胞行为及功能精确调控机制，以及其在体内对VECs生长及血管化作用机制。本项目将为水凝胶骨再生修复材料实现早期快速血管化以促进骨修复，提供重要理论和应用基础。

生物活性支架材料能够促进根尖周大范围骨病损的再生修复进程。支架材料内部有效构建血管网络是骨修复基础，也是制约材料发展的难点。目前水凝胶支架材料强度低，且细胞易于在水凝胶外围富集生长，即“边缘发展”。针对这个问题，本项目制备了可注射的、机械性能优良、具有自修复能力的双网络水凝胶；建立了VECs与BMSCs三维共培养体系，阐明了双细胞分泌VEGF及促血管分化的机制；在此基础上，成功制备了可缓释VEGF的水凝胶体系。通过外源性加入VEGF加强双细胞间的相互作用，并在裸鼠皮下埋植模型中验证，缓释VEGF水凝胶通过在局部维持VEGF的有效浓度，持续作用于VECs与BMSCs，成血管分化相关蛋白表达明显增高，皮下埋置水凝胶及其周围组织中有成熟的血管结构形成。本研究为水凝胶骨再生修复材料实现早期快速血管化以促进骨修复，提供重要理论和应用基础。