骨缺损修复过程存在血管化程度不足的问题，通过模拟生长因子的体内释放规律，可能促进干细胞的成血管和成骨分化功能。在前期合成的PLGA微球的基础上，通过改变PLA和PGA的比例调节PLGA微球的释放速率，制备不同释放速率的载VEGF和BMP-2基因的PLGA微球；扫描电镜和原子力显微镜表征其形貌特征，紫外分光光度计探讨基因控制释放规律，筛选与血管和骨再生相匹配的的载VEGF和载BMP-2基因的PLGA微球制备技术；体外研究将载VEGF和BMP-2基因的PLGA微球与细胞共培养，利用MTT、Realtime-PCR、Western blot等方法，研究其对BMSCs的增殖和分化功能的影响；体内研究向大鼠的颅骨临界骨缺损中植入可控释放VEGF和BMP-2基因的PLGA微球和BMSCs膜片，通过Micro-CT、组织学、免疫组织化学等测量研究其促进骨再生作用，为临床治疗口腔颌面部骨缺损奠定基础

In order to solve the problem of insufficient vascularization in bone regeneration,through mimicking the nature secretion sequence of growth factors may promote the angiopoiesis and osteogenesis of mesenchymal stem cells. Based on our previous works, PLGA microspheres were prepared. The release rate of the microspheres can be control by adjusting the ratio between PLA and PGA. In this study we will prepare PEI-alginate/pVEGF and PEI-alginate/pBMP-2 loaded PLGA microspheres with different release rate. Scanning electron microscopy and atomic force microscopy will be used to characterize its structure, ultraviolet spectrophotometer will be used to investigate the release of control. The purpose is to screen the best microspheres preparation technique for vascularization and bone formation. MTT assay, RT-qPCR and Western Blot will be used to study the effects of VEGF and BMP-2 gene loaded microspheres on proliferation, differentiation and function of BMSCs. Micro-CT, histology and immunohistochemistry techniques will be further used to examine the effects of VEGF and BMP-2 gene loaded microspheres combined with stem cell sheet on rat skull bone regeneration. This study will lay the foundation for treating bone defects using VEGF and BMP-2 gene loaded microspheres.