针对骨质疏松的RNAi功能化种植体的构建、功效及机制研究

Poor implant osseointegration under osteoporotic condition is an urgent problem in clinic. Modification by micro-nano topographies can hardly fulfil the requirement and accompany with other strategies is essential. Among them, using RNA interference technique to facilitate osteogenesis under osteoporotic condition is an ideal selection. The project was established on our previous study of biomimetic approach to fabricate micro-nano topographies and further validation was needed, followed by RNAi functionalization. The biocompatible chitosan was chosen as vector to formulate transfection complexes and the parameter was confirmed. Meanwhile, the cathodic electrodeposition method was chosen to fabricate the coating due to its neutralizaion mechanism that resulted in prolonged degradation manner. The loading amount and release profile were performed. The in vitro and in vivo effects were carried out with related cells and osteoporotic animals. Finally, the mechanisms of sustained release, transfection and osteogenic effect were performed to better guide the coating optimization. Ultimately, the project wants to find out a kind of implant that could retain ideal ossointegration for osteoporotic condition and provide a model for molecules immobilization on other biomaterials.

骨质疏松条件下的种植体骨结合是亟待解决的临床问题，仅依靠微纳米形貌修饰很难获得良好的骨结合，必须联合其它的种植体活化策略。RNAi技术可促进骨质疏松条件下的骨形成，因此，RNAi功能化有望成为一种理想选择。本课题在仿生微纳米形貌制备并对其生物学功能进行系统研究的基础上，针对骨质疏松条件进一步优化微纳米形貌，筛选骨质疏松条件下可促进骨形成的RNAi，选用生物相容性好的壳聚糖载体和可以达到长效缓释的阴极电沉积方法，对转染复合物及电沉积相关参数进行优化，构建RNAi功能化种植体。在此基础上，对其载荷量及缓释功能进行系统研究，采用骨质疏松动物模型和相关细胞对其转染和促骨结合功效进行系统评价并筛选出最佳的试样。最后，深入研究RNAi功能化种植体缓释、细胞转染及成骨作用的机制，为制备技术的进一步优化提供理论指导。最终形成可在骨质疏松条件下获得理想骨结合的功能化种植体，也为其他生物材料的活化提供参考。

提高骨质疏松条件下的种植体骨结合是亟待解决的临床问题。在形貌修饰的基础上，利用生物分子进行种植体的表面活化具有生物活性强、生物相容性好等优势，是目前较为常用的手段。利用 RNAi 技术对种植体表面活化具有作用靶向、稳定、持久等优点，是生物活化中的研究热点。为我们针对骨质疏松发病机制层面进行分子干预，进而提高骨质疏松条件下的种植体骨结合提供了技术条件。本课题提出，筛选合适的成骨siRNA/miRNA加载在种植体表面，通过反式转染，能够在材料表面发挥基因沉默作用，促进骨结合，同时提出，通过采用不同的基因加载方式和基因载体系统，能够优化核酸的加载，提高其在材料表面的可控性。本课题在前期研究基础上，采用细胞和分子生物学方法系统研究，证实该假设，并通过体内试验加以验证。旨在探明RNAi技术修饰种植体表面的可行性，通过对不同加载方法参数的控制，以实现加载量和释放模式的可控并探索其机制，同时探索适宜的植体表面核酸递送系统，为RNAi修饰种植体技术的进一步优化提供理论指导。最终形成可在骨质疏松条件下获得理想骨结合效果的功能化种植体，对于研究生物材料的活化具有重要意义。