力学增强型生物玻璃—陶瓷支架材料促进骨再生修复性能研究

目的: 构建一种低熔点含硼、锌生物玻璃（BG-ZnB）力学增强型生物玻璃-陶瓷的多孔支架材料，并探究BG-ZnB含量对支架的结构、力学性能和骨再生效率的影响。方法: 将质量分数为0%、2%、4%的BG-ZnB复合45S5生物活性玻璃通过石蜡微球造孔成型，经900℃烧结分别形成45S5/ZB0、45S5/ZB2、45S5/ZB4三种玻璃-陶瓷多孔支架；测定三种玻璃-陶瓷多孔支架的物相组成、孔隙率和压缩性能。36只雄性新西兰大白兔随机分为45S5/ZnB0组、45S5/ZnB2组和45S5/ZnB4组，将三种多孔支架置入兔骨缺损模型中，分别在第6周和第16周通过X射线摄片、显微CT三维结构重建和组织切片染色等方法检测大白兔骨缺损模型支架的骨再生效率；采用HE染色、Masson三色染色和EnVision二步法染色分析新生骨内生长情况。结果: 力学增强型生物玻璃-陶瓷与45S5生物活性玻璃的物相基本一致，但烧结后的支架在外观上有细微变形。45S5/ZnB2组和45S5/ZnB4支架骨架表面晶粒烧结更为致密，抗压强度较45S5/ZnB0支架明显提高（均P < 0.05）。支架植入后6周和16周时，45S5/ZnB2组和45S5/ZnB4组成骨率和骨小梁密度高于45S5/ZnB0组（均P < 0.05），新生骨、Ⅰ型胶原蛋白和骨钙素表达量较45S5/ZnB0组增加。结论: 低熔点高活性BG-ZnB助烧结工艺能构建出力学增强型生物玻璃-陶瓷多孔支架材料，可为研发骨损伤修复材料奠定实验基础。
Abstract: Objective: To evaluate the application of mechanically reinforced 45S5 Bioglass？-derived glass ceramic porous scaffolds for repair of bone defect in rabbits. Methods: The BG-ZnB powders were added into the 45S5 Bioglass？ powder/paraffin microsphere mixtures and were sintered at 900℃ to obtain porous scaffolds with highly bioactive BG-ZnB of 0%, 2% or 4% of mass fraction (denoted as 45S5/ZnB0, 45S5/ZnB2, 45S5/ZnB4). Phase composition, porosity and compression properties of three kinds of as-sintered scaffolds were characterized by X-ray analysis, mercury porosimetry, and mechanical test. Thirty-six male New Zealand rabbits with critical-sized femoral bone defects were randomly divided into three groups (45S5/ZnB0 group, 45S5/ZnB2 group and 45S5/ZnB4 group, 12 for each), and were implanted with three kinds of porous scaffolds respectively. X-ray, micro-CT three-dimensional reconstruction and tissue slice staining were used to detected the efficiency of bone regeneration at 6 and 16 weeks after operation. The growth of newly formed bone was observed using HE, Masson staining and EnVision method. Results: Phase compositions of 45S5/ZnB2 and 45S5/ZnB4 were the same with 45S5/ZnB0, but the average pore size and porosity of the scaffolds were decreased with the increase of BG-ZnB content. 45S5/ZnB2 and 45S5/ZnB4 scaffolds exhibited higher compressive strength, osteogenesis and trabecular density than those of the 45S5/ZnB0 scaffold (all P < 0.05). With the mechanical reinforcement of BG-ZnB increased, the content of new bone, collagen type I and osteocalcin increased. Conclusion: Low-melt BG-ZnB-assisted sintering is a promising approach to improve the mechanical strength of 45S5 Bioglass？. Key words: Femur/injuries Bone substitutes Boron Zinc Glass Silicon dioxide Biocompatible materials Materials testing Ceramics Bone regeneration Collagen Biomechanics