次序释放VEGF和BMP的新型3D打印仿生支架促进创伤性大段骨缺损修复

In the treatment of traumatic large bone defects with 3D printed implants, the osseointegration of the implant-bone interface is a key event that determines the effect of treatment. Angiogenesis and osteogenesis occur sequentially in time during bone defect repair, so preparing a bionic composite scaffolds spatially and temporally is important to the treatment of traumatic bone defects. In our preliminary work, we have prepared uniform and controlled PCL microspheres which can preserve the encapsulated drug’s activity by emulsion preparation method. Besides, we tested the drug release profile of the polycaprolactone microspheres and silk fibroin gelatin and founded that the releasing time separately matched with the time window of angiogenesis and osteogenesis in vivo. This project intends to use the BMP-capsuled polycaprolactone microspheres prepared in the previous work to combine with VEGF-coated silk fibroin by means of enzyme cross-linking, and then form a new type of 3D printed composite scaffolds for releasing VEGF and BMP in sequence to simulate a more physiologically compliant bone repair process. Through establishing the rat femur defect model, X-ray, Micro-CT, hard tissue section, biomechanical detections and immunohistochemistry were used to verify the effect of bone fusion and further explore its osteogenic mechanism to provide a theoretical basis for the application of 3D printing technology in the repair of traumatic bone defects.

在3D打印对创伤性大段骨缺损的治疗中，假体-骨界面的融合是决定治疗成败的关键。而假体-骨界面融合过程中成血管和成骨作用的发生具有时间次序性，如何制备出空间上和时间上仿生的复合支架是治疗创伤性大段骨缺损的研究方向之一。在前期工作中，本课题组已通过乳液法制备出了可保留药物活性的聚己内酯微球，并分别对聚己内酯微球和蚕丝蛋白凝胶的药物释放曲线进行了检测，发现两者的药物释放时间分别与体内成血管和成骨作用的时间窗口一致。本研究拟在此基础上，通过酶交联的方式将包裹BMP的聚己内酯微球与负载VEGF的蚕丝蛋白凝胶形成次序释放VEGF和BMP的新型3D打印仿生支架，建立大鼠骨缺损模型，采用X线、Micro-CT、硬组织切片、生物力学和免疫组化等方法，观察假体-骨界面的成骨情况，验证其是否能在体内更快得实现假体-骨界面稳定的骨性融合，并初步探讨其成骨机制，为3D打印技术应用临床治疗创伤性大段骨缺损提供依据。

在3D打印对创伤性大段骨缺损的治疗中，假体-骨界面的融合是决定治疗成败的关键。而假体-骨界面融合过程中成血管和成骨作用的发生具有时间次序性，如何制备出空间上和时间上仿生的复合支架是治疗创伤性大段骨缺损的研究方向之一。本研究通过酶交联的方式将包裹BMP的PLGA载药微球与负载VEGF的SF凝胶形成次序释放VEGF和BMP的新型3D打印仿生支架，在体外验证了其良好的生物安全性和生物活性，并可以在合适的时间窗口先后释放VEGF和BMP。随后建立大鼠骨缺损模型，采用X线、Micro-CT、组织切片等方法，观察假体-骨界面的成骨情况，初步得出了新型3D打印仿生支架能在体内更快得实现假体-骨界面稳定的骨性融合（部分结果仍在整理，文章正在书写待投稿中），有望为3D打印技术应用今后应用临床治疗创伤性大段骨缺损提供理论依据。