Human Development and Health, University of Southampton Medical School, Southampton, UK.
Acta Biomater. 2012 May;8(5):1918-27. doi: 10.1016/j.actbio.2012.01.024. Epub 2012 Jan 24.
Disease transmission, availability and cost of allografts have resulted in significant efforts to find an alternative for use in impaction bone grafting (IBG). Recent studies identified two polymers with both structural strength and biocompatibility characteristics as potential replacements. The aim of this study was to assess whether increasing the polymer porosity further enhanced the mechanical and cellular compatibility characteristics for use as an osteogenic biomaterial alternative to allografts in IBG. Solid and porous poly(DL-lactide) (P(DL)LA) and poly(DL-lactide-co-glycolide) (P(DL)LGA) scaffolds were produced via melt processing and supercritical CO(2) foaming, and the differences characterized using scanning electron microscopy (SEM). Mechanical testing included milling and impaction, with comparisons made using a shear testing rig as well as a novel agitation test for cohesion. Cellular compatibility tests for cell number, viability, and osteogenic differentiation using WST-1 assays, fluorostaining, and ALP assays were determined following 14 day culture with skeletal stem cells. SEM showed excellent porosity throughout both of the supercritical-foam-produced polymer scaffolds, with pores between 50 and 200 μm. Shear testing showed that the porous polymers exceeded the shear strength of allograft controls (P<0.001). Agitation testing showed greater cohesion between the particles of the porous polymers (P<0.05). Cellular studies showed increased cell number, viability, and osteogenic differentiation on the porous polymers compared to solid block polymers (P<0.05). The use of supercritical CO(2) to generate porous polymeric biodegradable scaffolds significantly improves the cellular compatibility and cohesion observed compared to non-porous counterparts, without substantial loss of mechanical shear strength. These improved characteristics are critical for clinical translation as a potential osteogenic composite for use in IBG.
疾病传播、同种异体移植物的可及性和成本促使人们做出巨大努力，寻找一种替代移植物用于压配性骨移植（IBG）的材料。最近的研究发现，有两种聚合物具有结构强度和生物相容性特征，可作为潜在替代品。本研究旨在评估进一步增加聚合物孔隙率是否可以提高其机械和细胞相容性特征，以替代 IBG 中的同种异体移植物作为骨生成生物材料。通过熔融加工和超临界 CO2 发泡制备了实心和多孔聚（DL-乳酸）（P（DL）LA）和聚（DL-乳酸-共-乙醇酸）（P（DL）LGA）支架，并通过扫描电子显微镜（SEM）对其进行了表征。力学测试包括铣削和压配，使用剪切测试装置以及新颖的搅拌测试对凝聚力进行了比较。采用 WST-1 检测、荧光染色和碱性磷酸酶（ALP）检测，在与成骨干细胞共培养 14 天后，对细胞数量、活力和成骨分化进行了细胞相容性测试。SEM 显示，两种超临界发泡聚合物支架都具有出色的多孔性，孔隙大小在 50-200 μm 之间。剪切测试表明，多孔聚合物的剪切强度超过了同种异体移植物对照组（P<0.001）。搅拌测试表明，多孔聚合物颗粒之间的凝聚力更大（P<0.05）。细胞研究表明，与实心块状聚合物相比，多孔聚合物的细胞数量、活力和成骨分化均增加（P<0.05）。与非多孔聚合物相比，使用超临界 CO2 生成多孔可生物降解聚合物支架可显著提高细胞相容性和凝聚力，而不会显著降低机械剪切强度。这些改进的特性对于临床转化至关重要，因为它是一种潜在的用于 IBG 的成骨复合材料。
