三维连续介孔生物活性玻璃纳米管载体支架的制备、双因子控释及骨修复性能研究

Carrier scaffolds with controllable releasing profiles are crucial to the development of tissue engineering. In this work, a novel three-dimensional (3D) mesoporous bioglass nanotube carrier scaffold with controllable releasing profiles is proposed. The proposed carrier scaffold combines the ideal scaffold structure and the ideal carrier structure. The carrier scaffold will be fabricated via template-assisted sol-gel process followed by heat treatment by using 3D bacterial cellulose nanofibrous scaffold as the template. A small-sized bone promoting factor, statin small molecule, will be impregnated into the inner room of the mesoporous nanotubes and the large-sized BMP2 (bone morphogenetic protein 2) will be loaded on the external surface of the nanotubes. The releasing profiles can be controlled by heparin loading, mesopore size, nanotube dimension and chemical composition, leading to a controllable releasing of these two bioactive factors, which in turn, results in reduced high-cost BMP2 dosage and improved bone formation. X-ray absorption near edge structure technique will be used to in situ investigate the early formation of inorganics at the surface of BC nanofibers. In addition, the preparation of the carrier scaffold and the controllable releasing profiles of the two bioactive factors will be studied. The emphasis of this work will be placed on the dependence of the cell behavior and in vivo bone formation on the releasing profiles of the two factors and the synergistic effects of the two factors. The findings in this work will pave a new way of designing and fabricating high performance carrier scaffolds.

能适时释放适量生长因子的理想载体支架对组织工程学的发展至关重要。根据支架发展的新趋势，本项目率先提出将理想支架结构与理想载体结构相结合的新思路，并构思了三维连续介孔生物活性玻璃纳米管载体支架的制备方案。拟以三维连续细菌纤维素（BC）纳米纤维为模板，采用模板辅助溶胶凝胶结合热处理法制备该载体支架，然后依据分子尺寸的差异，分别将可促进骨修复的他汀小分子和骨形态发生蛋白（BMP2）负载于纳米管腔内与表面，并通过肝素化和介孔尺度与管壁厚等的变化调节双因子的释放剂量和时长，以实现双因子的可控释放，减少昂贵BMP2的用量，并可望因双因子的协同提高骨修复效果。本项目拟率先采用X射线吸收近边结构技术原位跟踪无机相在BC表面的初始形成过程，在完成载体支架制备科学研究的基础上，重点揭示双因子的可控释放对细胞行为及体内骨修复性能的调控规律，探究双因子的协同作用机制，为设计和制备高性能载体支架提供新的原理和方法。

以BC为模板，对生物活性玻璃纳米管制备工艺参数进行了研究，获得了三维连续介孔生物活性玻璃纳米管支架，以三嵌段共聚物EO20PO70EO20为致孔剂，获得了三维连续介孔生物活性玻璃纳米管，并从分子水平上阐明了无机相结构演变规律。通过对致孔剂含量、溶液组成、醇水比、陈化时间和煅烧温度等制备工艺参数的优化，实现了对生物活性玻璃纳米管的介孔尺寸的有效调控。在此基础上，项目对三维有序介孔生物活性玻璃纳米管支架的药物装载和释放动力学进行了研究，并与三维生物活性玻璃纳米管支架进行了对比。结果发现，其装载量约为后者的3倍，且能够实现辛伐他汀（SIM）和BMP-2药物的可持续缓慢释放。三维有序介孔生物活性玻璃纳米管支架负载SIM和BMP-2的体外生物学行为与体内骨修复性能研究发现，支架具有良好的体外生物活性，有利于hBMSCs细胞的增殖和分化，而SIM和BMP-2的加入提高了hBMSCs细胞在支架上的增殖和分化能力，且支架有效地保护了BMP-2蛋白的生物活性。动物实验（负载辛伐他汀及BMP-2的三维连续介孔BG纳米管载体支架的体内骨修复）结果显示，同时载有SIM和BMP-2的支架比其它组观察到更多的新骨形成。