钙镁硅系生物陶瓷溶出离子对骨再生相关生长因子表达的促进效应及其对骨组织再生的调控

Bone-related growth factors play a crucial role in building bioactive tissue-engineered bone. Nevertheless, the soluble growth factors present some disadvantages in clinical application, including easy inactivation, potential toxicity and dose-dependent manner and the need for repeat surgery supplement. It has been reported that the ionic products released from CaO-MgO-SiO2-based bioceramics could promote cell proliferation, differentiation and expression of bone tissue related genes, and stimulate bone and vascular regeneration in vivo and in vitro. The cooperative effects of different concentrations of Ca, Mg, Si and the ion combination on cell metabolism, angiogenesis, expression of bone-related growth factors and gens as well as the reaction mechanism are studied in this research, and then the critical concentrations of different ions for bone regeneration and the optimal ions combination stimulating new bone growth, vascularization and expression of bone regeneration-related growth factors and genes are found. On this basis, according to the CaO-MgO-SiO2 ternary phase diagram, through adjusting the ratio of CaO, MgO and SiO2, a novel CaO-MgO-SiO2-based bioceramics which could release a certain concentration rang of Ca, Mg，Si ions to induce bone regeneration can be designed and synthetized. The relationship between chemical composition and ion release kinetic, bioactivity in vitro, therapeutic effect of the bioceramics on bone regeneration in vivo as well the mechanism are explored, which can be served as the theoretical and experimental basis for designing and synthetizing a novel bone tissue-engineered scaffold whose ion release kinetic and biological response can be artificially controlled.

骨再生相关生长因子对构建生物活性组织工程骨起着关键的作用，但可溶性生长因子存在易失活、潜在毒性和剂量依赖性以及需反复手术补充等实际应用障碍。研究表明钙镁硅系生物陶瓷的溶出离子能够促进骨组织细胞增殖、分化及相关基因表达，在体内外均能刺激骨和血管再生。本研究在分析不同浓度的钙、镁、硅离子及离子组合对骨组织细胞代谢、血管生成相关生长因子及基因表达的显著性及协同效应并探索其作用机理，找出骨再生所需离子的临界浓度及促进新骨生长、血管化相关生长因子及基因表达的最佳离子组合的基础上，参考相图，调整CaO、MgO、SiO2三者比例，设计制备出通过逐渐释放一定比例的钙、镁、硅离子而对骨再生具有诱导效应的新型钙镁硅系陶瓷。探索其离子释放动力学特性与组分之间的关系、体外生物活性功能及其在体内对骨再生修复治疗的效能和机理等，为设计制备出离子释放动力学及生物学响应可控的新型骨组织支架材料提供实验依据和理论基础。

骨再生相关生长因子对构建生物活性组织工程骨起到关键作用，但可溶性生长因子存在易失活、潜在毒性以及需二次手术等实际应用障碍。钙镁硅系生物陶瓷的溶出离子因能促进骨组织细胞增殖、分化及相关基因表达，刺激骨和血管再生而成为研究热点。本研究在探索不同浓度钙镁硅离子及离子组合对骨再生调控作用的基础上，设计制备可逐渐释放一定比例钙镁硅离子而诱导骨再生的新型钙镁硅系多相复合陶瓷材料。首先，探索了钙、镁、硅离子对骨组织相关细胞生长、代谢和功能表达的显著性及协同作用效应，发现一定浓度范围内单一钙、镁、硅离子即能促进MG63、HUVEC、L929细胞增殖，而钙、镁、硅离子组合则能促进BMSC细胞增殖并诱导其成骨分化。其次，研究了钙镁硅系单相陶瓷组分与性能的关系。基于前期工作基础，参考三元相图，调整CaO、MgO、SiO2三者比例，初步设计制备出两种以硅酸钙、硅酸二钙和镁黄长石为主晶相的多相陶瓷材料。通过组分优化设计，制备出化学组成为43.30%CaO-10.72%MgO-45.98%SiO2 (mol%)的多相复合陶瓷MC1。该陶瓷的杨氏模量与人体皮质骨最为相近，且热膨胀系数与钛合金TC4相匹配，在骨修复领域中的应用具有多种可能性。考察了MC1多相陶瓷材料的体外生物学特性、其在体外浸提介质中的离子溶出行为及溶出离子对细胞的影响。发现少量硅离子即可促进BMSC、MG63和HUVEC细胞增殖或成骨分化；硅离子存在时，高浓度钙离子(100~120 ppm)能更有效地促进BMSC、MG63成骨分化同时刺激BMSC、HUVEC分泌BMP-2和VEGF等生长因子。最后，研究了该复合陶瓷材料的体内效能，结果显示其在体内表现出优异的组织相容性、骨整合性和骨诱导性。总之，本研究初步探索陶瓷离子释放动力学特性与组分之间的关系、体外生物活性及其体内骨修复效能和机理等，为设计制备出离子释放动力学及生物学响应可控的新型骨组织修复材料提供了初步实验依据和理论基础。