多功能羟基磷灰石纳米晶的控制合成及其在活性组织工程骨构建中的应用

The combination of bone tissue engineering and gene therapy offers new research strategies to enhance the regeneration of bone. In this project, we focuse on the controlled synthesis of luminescent functional HAp:Yb3+, Er3+ nanospheres and porous HAp:Eu3+ nanorods firstly. Bone mesenchymal stem cells (BMSCs) can be transfected by HAp:Yb3+, Er3+ nanospheres loading plasmid bone morphogenetic protein-2 (pBMP-2/HAp), the BMSCs express BMP-2 and BMP-2 can promote BMSCs osteogenic differentiation. HAp:Yb3+, Er3+ nanospheres both have the functions of gene plasmid carriers and up-conversion fluorescent label. Porous HAp:Eu3+ nanorods can load growth factors. The hydrophilicity of thermo-responsive multiblock poly(ester urethane)s (EPC), which comprises poly(ethylene glycol) (PEG), poly(propylene glycol) (PPG) and poly(ε-caprolactone) (PCL) segments, could be controlled by changing the temperature of the environment. HAp:Eu3+ nanorods contained EPC hydrogel composite fibers, which both have functions of scaffold materials and growth factors carriers, can be prepared via electrospinning. The amount of the growth factors releasing from HAp:Eu3+/EPC scaffolds increases with the elevated environmental temperature. Finally, we intent to transfect pBMP-2/HAp into BMSCs, these gene-modified BMSCs are seeded onto growth factors loaded HAp:Eu3+/EPC scaffolds, the synergistic effect of BMP-2 and growth factors on osteogenic differentiation and bone formation are investigated in detail so as to construct bioactive tissue engineering bone materials with gene transfected stem cells attaching and growth factors loading.

骨组织工程和基因治疗的结合为骨组织再生修复提供了新的研究思路。本项目拟控制合成光功能化的球形HAp:Yb3+,Er3+纳米晶和多孔棒状HAp:Eu3+纳米晶；利用前者携带骨形态发生蛋白2 质粒(pBMP-2/HAp)转染骨髓间充质干细胞(BMSCs)，使其表达BMP-2蛋白并促进BMSCs 的成骨分化，HAp:Yb3+,Er3+兼具质粒载体和上转换荧光标记的功能；多孔HAp:Eu3+纳米棒能够担载生长因子，利用静电纺丝将其与温敏性聚酯型聚氨酯复合在一起制备水凝胶复合纤维。温度升高使温敏性水凝胶纤维收缩并将生长因子释放出来，水凝胶纤维具有支架材料和生长因子载体的功能。最后将pBMP-2/HAp 转染的BMSCs与担载生长因子的HAp:Eu3+/EPC 支架材料在体外复合，研究BMP-2 和生长因子协同作用下BMSCs的成骨分化性能，从而构建一种携带基因转染的干细胞和生长因子的活性组织工程骨。

骨组织工程和基因治疗的结合为骨组织再生修复提供了新的研究思路。本项目结合天然骨中羟基磷灰石结构和形貌，优化合成条件，获得形貌可控、尺寸均匀、结晶度高、分散性好的稀土离子(Ln3+)掺杂的HAp纳米棒和超长纳米线，稀土离子能够作为荧光标记来监测蛋白传递及骨缺损修复情况。将HAp:Ln3+ (Ln= Yb,Er,Gd)作为骨形态发生蛋白-2 (BMP-2)的载体材料，系统研究了HAp:Ln3+的促成骨性能及生物相容性，HAp:Ln3+/BMP-2可促进MC 3T3-E1细胞的增殖和分化。分别采用溶剂热和水热法合成了HAp:Eu3+纳米棒和超长纳米线，表面修饰PEG提高生物相容性。HAp:Eu3+超长纳米线可形成网状结构材料，与HAp:Eu3+纳米棒复合聚己内酯材料均可作为成骨植入材料，细胞层面和活体水平研究结果表明HAp:Eu3+纳米棒和超长纳米线两种材料均有骨诱导效果，Eu3+荧光性能可监测成骨过程。纳米线构成的网状支架组骨诱导效果与复合纳米材料组促进成骨性能相近，表明HAp:Eu3+超长纳米线无需引入高分子支架材料即可获得良好骨组织修复性能，从而构建一种携带长因子的诱导干细胞成骨分化的活性组织工程骨。