Department of Materials Science and Engineering and Center for Bone and Tissue Repair and Regeneration, Missouri University of Science and Technology, Rolla, MO 65409, USA.
Acta Biomater. 2013 Jul;9(7):7506-17. doi: 10.1016/j.actbio.2013.03.039. Epub 2013 Apr 6.
The repair of large bone defects, such as segmental defects in the long bones of the limbs, is a challenging clinical problem. Our recent work has shown the ability to create porous scaffolds of silicate 13-93 bioactive glass by robocasting which have compressive strengths comparable to human cortical bone. The objective of this study was to evaluate the capacity of those strong porous scaffolds with a grid-like microstructure (porosity=50%; filament width=330μm; pore width=300μm) to regenerate bone in a rat calvarial defect model. Six weeks post-implantation, the amount of new bone formed within the implants was evaluated using histomorphometric analysis. The amount of new bone formed in implants composed of the as-fabricated scaffolds was 32% of the available pore space (area). Pretreating the as-fabricated scaffolds in an aqueous phosphate solution for 1, 3 and 6days to convert a surface layer to hydroxyapatite prior to implantation enhanced new bone formation to 46%, 57% and 45%, respectively. New bone formation in scaffolds pretreated for 1, 3 and 6days and loaded with bone morphogenetic protein-2 (BMP-2) (1μg per defect) was 65%, 61% and 64%, respectively. The results show that converting a surface layer of the glass to hydroxyapatite or loading the surface-treated scaffolds with BMP-2 can significantly improve the capacity of 13-93 bioactive glass scaffolds to regenerate bone in an osseous defect. Based on their mechanical properties evaluated previously and their capacity to regenerate bone found in this study, these 13-93 bioactive glass scaffolds, pretreated or loaded with BMP-2, are promising in structural bone repair.
修复大骨缺损，如四肢长骨的节段性缺损，是一个具有挑战性的临床问题。我们最近的工作表明，通过机器人铸造技术可以制造出硅酸 13-93 生物活性玻璃的多孔支架，其抗压强度可与人类皮质骨相媲美。本研究的目的是评估具有网格状微观结构（孔隙率=50%；丝宽=330μm；孔径=300μm）的强多孔支架的能力，以在大鼠颅骨缺损模型中再生骨。植入 6 周后，通过组织形态计量学分析评估植入物内新骨形成的量。由原样制造的支架组成的植入物中形成的新骨量占可用孔隙空间（面积）的 32%。在植入前，将原样制造的支架在磷酸水溶液中预处理 1、3 和 6 天，将表面层转化为羟基磷灰石，可分别将新骨形成量提高到 46%、57%和 45%。在预处理 1、3 和 6 天并加载骨形态发生蛋白-2（BMP-2）（每个缺损 1μg）的支架中，新骨形成量分别为 65%、61%和 64%。结果表明，将玻璃的表面层转化为羟基磷灰石或在表面处理后的支架上加载 BMP-2 可以显著提高 13-93 生物活性玻璃支架在骨缺损中再生骨的能力。基于之前评估的机械性能和本研究中发现的骨再生能力，这些预处理或加载 BMP-2 的 13-93 生物活性玻璃支架在结构性骨修复中具有广阔的前景。
