新型多分级仿生硅化骨胶原支架的构建及其促成骨活性研究

The worldwide is experiencing increasing incidence of bone defect and more than 2.2 million bone grafting procedures are happening annually. Extensive studies have reported the considerable shortcomings, limitations, and complications of current clinical treatments and bone grafts for bone repair and regeneration. Thus developing of functional bone graft materials to replace the lost region of bone has been a formidable challenge in both orthopaedics and biomaterials research. By mimicking the arrangement of collagen and minerals in natural bone, we have successfully developed a strategy for intrafibrillar silicification of reconstituted type I collagen and proved the osteogenesis and angiogenesis potential of the silicified collagen scaffolds. However, this kind of bone substitute material is lack of the hierarchical structure of natural bone which is critical to mechanical properties. In addition, the mechanism of the osteogenic potential and the postoperative transformation of this material are not clear yet. Thus, based on the biomimetic intrafibrillar silicification concept we reported previously, in the present project, by taking advantages of the biogenic hierarchical structures of bovine bone collagen matrices, we aim to develop a novel collagen-silica composites with different levels of sophisticated hierarchical structures, via a polyamine-induced liquid precursor process. Furthermore, we will also explore the osteoinductive potential of the novel intrafibrillarly silicified bone matrix on mesenchymal stem cells and the intrafibrillar-mineralization inducing function of the mesenchymal stem cells on the silicified scaffolds, with both in vitro and in vivo experiments. This research will result in a novel functional bone grafts with lower immunogenicity, higher mechanical properties and better osteogenesis activity. In addition, this research is of great means to reveal the mechanism of intrafibrillar silicification, and the interaction between the intrafibrillarly-silicified bone matrix and mesenchymal stem cells. The accomplishment of this project will provide a promising strategy for the clinical application of biomimetic mineralization technique and a novel intrafibrillar-silicified bone graft material with biogenic hierarchical structure.

外伤等原因导致的骨缺损十分常见，严重影响患者生存质量。目前使用的骨修复材料仍存在来源有限、疾病传播、免疫排斥等问题，因此，生物骨衍生材料及人工合成材料的研发是骨科及生物材料领域面临的重要课题。我们前期首次实现了重组I型胶原的纤维内快速硅化，并证实该硅化胶原支架可促进骨髓间充质干细胞（BMSC）成骨分化及血管内皮前体细胞成血管分化，显示了其在骨缺损修复领域中的应用前景。然而，该支架材料仍存在缺乏自然骨的分级结构、促成骨机制及体内转归机制不明等问题。本研究拟在脱抗原自然骨胶原基质分级结构基础上，构建多分级仿生硅化骨支架材料，并探索其纤维内仿生硅化机理；进而围绕硅化骨支架促进BMSC成骨分化及BMSC促进硅化骨支架纤维内仿生矿化转变等问题，研究支架与BMSC的交互作用规律及相关分子机制。本项目的完成有望构建出免疫原性低、机械性能强、成骨活性高的新型骨替代材料，具有积极的理论指导和临床应用意义。

课题首先完善了新型纤维内仿生硅化骨胶原支架材料的制备工艺，形成以纤维内二氧化硅有序沉积为特征的硅化仿生骨胶原支架，并完成了材料理化及机械性能的评价；其次，探明了仿生硅化过程的作用机制，为这一技术的不断完善提供作用靶点。在构建的仿生硅化骨的基础上，我们通过小鼠颅骨骨缺损模型的修复研究，发现这种仿生硅化支架材料能够更好地促进血管再生与骨再生，并且材料能够通过对宿主免疫系统的调控，与单核细胞发生作用并促进其分泌一系列相关细胞因子，一方面能够促进宿主修复种子细胞的募集，另一方面能够更好地促进缺损区域的血管化形成。显示出这种新形成的仿生硅化支架材料具有良好的骨缺损修复效果，为其转化应用提供了相关的动物实验研究基础。我们对仿生硅化骨促成骨成血管作用的分子机制进行了进一步深入的研究探索，详细揭示了仿生硅化骨胶原支架材料在原位骨缺损修复过程中与宿主之间相互作用的关系，从而指导材料的进一步完善。课题成果在Nat Mater(IF:39.737)、Prog Polym Sci (IF: 25.766)、Adv Funct Mater (IF: 12.124)等权威杂志发表SCI论文13篇，其中影响因子大于30的1篇,大于20的1篇，大于10的1篇，大于5的5篇，获批国家发明专利3项，实用新型专利2项，在国际会议做大会发言2次，并举办了两届仿生矿化精粹论坛，受到国内外学者的一致好评。