三维打印制备介孔生物玻璃/聚乳酸复合支架协同超声刺激促进骨修复研究

The development of multifunctional biomaterial scaffolds with the combined functionalities of biological factors and biomaterials and synergistic biophysical stimulation are of great importance in clinical bone repair, which could enhance osteogenic ability for fast osseointegration with host bone. However, it is still challenging to design and fabricate such multifunctional scaffolds to match clinical applications. .In this research proposal, multifunctional scaffolds will be prepared by 3D printing technique, which composed of ultrasonic microbubbles for gene delivery, mesoporous bioactive glass (MBG) for drug delivery and biodegradable polylactic acid (PDLLA). 3D printing technique is an ideal method to fabricate the MBG/PDLLA scaffolds, which can construct the complex structures, adjust the inner structures and enhance the mechanical property. PDLLA ultrasonic microbubbles with the encapsulation of high amount of plasmid DNA will load into the MBG/PDLLA scaffolds to form the PDLLA microbubbles-loaded MBG/PDLLA composite scaffolds. Under the ultrasonic stimulation, plasmid DNA could efficiently transfer into osteoblast cells and stimulate the express of VEGF, BMP growth factors, and thereby promote bone regeneration. At the same time, ultrasonic treatment can stimulate the cells metabolism, adjust the cells activity, which also are beneficial for bone repair. Furthermore, MBG in the scaffolds has the ability to sustained release drugs (such as antibiotics, bone resorption inhibitor), resulting in the inhibitions of infection and bone resorption. .In this study, we proposed a novel concept to design and construct multifunctional MBG/PDLLA composite scaffolds with the functionalities of ultrasonic biophysical stimulation, plasmid DNA transfection to express growth factors and local sustained drug delivery, which can regulate and promote bone repair with synergistic effects. We believe that this novel and original research proposal is highly scientific and feasible, and the research results would promote the development of MBG/PDLLA composite scaffolds for clinical application in bone repair.

设计和构建整合生物信号因子与支架生物材料功能，并协同生物物理刺激的多功能骨修复支架对临床骨缺损修复具有重要意义。本项目拟提出三维打印设计制备支架组成包括超声微泡基因载体、介孔生物玻璃(MBG)药物载体和聚乳酸(PDLLA)的多功能支架，实现支架在复杂结构构建、内部结构调控、机械性能提高等方面可控；超声微泡装载足量质粒DNA与MBG/PDLLA支架复合，获得外部超声刺激介导质粒DNA高效靶向转移和促进表达VEGF、BMP-2等生长因子，同时超声刺激促进缺损部位细胞代谢、调节细胞活动而加速骨缺损修复；支架中MBG可实现抗生素、骨吸收抑制剂等药物缓释而抵御局部感染或骨吸收。本项目构建结合低强度脉冲超声的生物物理刺激、质粒DNA靶向转移和表达以及药物原位缓释协同作用的复合支架，多路径调控和促进骨缺损修复的研究策略是骨缺损修复研究的新发展，具有创新性，为高效促进骨缺损修复的临床应用提供理论基础。

发展用于促进骨修复的多功能组织工程支架材料具有明显的社会和经济意义。本项目从多路径调控和促进骨修复为目标，提出将生物活性良好的介孔生物玻璃、促成血管药物DMOG和超声刺激作用相结合来设计和3D打印制备多功能骨修复支架，在细胞水平和动物水平证实以上策略能够协同促进骨修复，为用于临床骨缺损修复治疗的多功能骨修复材料设计提供参考。本项目完成原定研究计划，并取得多项重要的研究结果。.通过3D打印制备预先进行结构设计的介孔生物玻璃/聚乳酸（MBG/PDLLA）复合支架和双重乳液挥发法制备高DMOG药物包封率的PDLLA微球（DMOG/PDLLA），采用直接涂覆方法制备了负载DMOG/PDLLA微球的MBG/PDLLA复合支架（DMOG/PDLLA-MBG/PDLLA）。该复合支架具有缓慢降解性能，降解21天后的环境pH稳定在7.7；体外药物释放表明超声刺激能够加速DMOG释放速率。细胞实验结果表明，骨髓间充质干细胞（BMSCs）能够在该复合支架上增殖，并且超声刺激和DMOG释放协同促进BMSCs的增殖和碱性磷酸酶（ALP）活性表达，展现出超声刺激协同促进成骨分化的潜力。.提出将DMOG直接负载在MBG孔道（DMOG-MBG）来代替PDLLA微球负载DMOG，并3D打印制备DMOG-MBG与PDLLA的复合支架（D-MBG/PDLLA），不仅确保了复合支架中稳定的DMOG负载量，而且同样实现超声刺激能够加速DMOG释放速率。细胞实验结果表明，超声刺激和DMOG释放均能促进内皮细胞（HUVECs）和BMSCs的细胞粘附、增殖与分化，而且超声刺激与DMOG释放联合能够协同促进HUVECs和BMSCs的生物学响应。进一步以大鼠颅骨缺损模型证实了D-MBG/PDLLA复合支架在超声刺激和DMOG释放的协同作用下促进体内骨缺损修复的能力，为多路径调控和促进骨修复支架的设计制备提供新思路和理论依据。.另外，项目执行过程中还拓展研究了兼具骨肿瘤治疗与骨组织修复的多功能复合支架，设计并构建了多种具有光热效应的3D打印生物陶瓷复合支架，证实了这些复合支架既能高效光热治疗骨肿瘤又能促进骨缺损修复的功能，为兼具疾病治疗与骨组织修复功能的生物陶瓷材料的研发提供新思路，具有重要的指导意义。.项目已发表SCI论文12篇，投稿中SCI论文2篇，申请发明专利4项。