低温3D打印多级孔仿生骨海绵缓释DPSCs外泌体促H型血管新生及骨再生的功能机制研究

血管化是大尺寸及难愈性骨缺损修复时亟待解决的关键瓶颈。近来新发现的骨内特异性H型血管对增强“成血管-成骨偶联”及促进再生骨组织的血管化至关重要。既往促血管化的方案大多忽视了H型血管和骨生成之间的偶联作用，对如何调控H型血管形成以促进血管化骨再生及相关分子机制的研究鲜见。我们的前期研究发现，经PDGF-BB预处理的牙髓干细胞（DPSCs）外泌体能促进H型血管内皮细胞的形成及干细胞的成骨分化，且该作用可能与Notch通路的调控有关。本项目拟在前期研究基础上，探明该外泌体中发挥功能作用的关键因子（包括miRNAs）及其调控Notch通路促H型血管形成的具体机制，进一步采用低温3D打印技术制备能缓释DPSCs外泌体的多级孔仿生骨海绵支架，通过体内外实验，系统性地研究该复合支架促H型血管形成、增强“成血管-成骨偶联”及血管化骨再生的作用及机制。研究结果可为大尺寸及难愈性骨缺损修复提供新思路和新技术。

Vascularization is the key bottleneck that needs to be urgently solved when repairing large-sized and difficult-to-heal bone defects. The newly discovered intra-osseous specific type H blood vessels are essential to enhance the "angiogenesis-osteogenesis coupling" effect and promote the vascularization of regenerated bone tissue. Previous strategies have mostly neglected the coupling effect between type H blood vessels and osteogenesis, and there are few studies on how to regulate the formation of type H blood vessels to promote vascularized bone regeneration and related molecular mechanisms. Our previous studies found that the exosomes of dental pulp stem cells (DPSCs) pretreated with PDGF-BB can promote the formation of type H vascular endothelial cells and the osteogenic differentiation of stem cells, and this effect may be related to the regulation of Notch signaling pathway. In this project, based on the previous research, we plan to explore the key factors (including miRNAs) that play a functional role in these exosomes and their specific mechanisms in regulating the Notch pathway to promote the formation of type H blood vessels, and further use low-temperature 3D printing technology to prepare hierarchical porous sponge-like biomimetic scaffolds to sustainably release the exosomes from DPSCs. Through in vitro and in vivo experiments, systematically study the role and mechanism of these composite scaffolds in promoting the formation of type H blood vessels, enhancing the "angiogenesis-osteogenesis coupling" and facilitating vascularized bone regeneration. The expected findings can provide new ideas and novel techniques for large-sized and difficult-to-heal bone defect repair.