Biomedical Engineering and Biotechnology Doctoral Program, University of Massachusetts, Lowell, Massachusetts 01854, USA.
J Biomed Mater Res A. 2011 Mar 15;96(4):632-8. doi: 10.1002/jbm.a.33016. Epub 2011 Jan 25.
The purpose of this study was to optimize a novel biodegradable polymer for drug eluting stent (DES) applications. Degradation profiles of different poly(D,L-lactide-co-glycolide)/amorphous calcium phosphate (PLGA/ACP) composites coated on stents were studied both in vitro and in vivo for three months. For the in vitro study, stents were immersed into the phosphate buffered saline (37 °C, pH 7.4) with constant shaking. The polymer weight loss was measured weekly and morphological changes were analyzed. The results demonstrated that approximately 60% of polymer was degraded within the three-month period and there was no significant difference between the different PLGA/ACP composites. However, the composite of 50% PLGA (65/35) with 50% ACP showed a slightly faster degradation rate than other composites. Morphologically, all stent surfaces changed from a micro-porous before degradation to a corrugated solid micro-net-like structure at two months post degradation. Based on in vitro results, 65% PLGA (65/35) with 35% ACP) coated stents were selected and implanted into rat aortas (n = 12) for the in vivo study. Microscopic observation showed that no composite was found on any of the implanted stents at 12 weeks post implantation, which indicated the selected PLGA/ACP composite is desired for DES applications.
本研究旨在优化一种新型可生物降解聚合物，用于药物洗脱支架 (DES) 应用。研究了不同聚 (D,L-丙交酯-共-乙交酯)/无定形磷酸钙 (PLGA/ACP) 复合材料在支架上的体外和体内三个月的降解情况。体外研究中，支架被浸入磷酸盐缓冲盐水（37°C，pH7.4）中，进行恒速搅拌。每周测量聚合物的重量损失，并分析形态变化。结果表明，在三个月内约有 60%的聚合物被降解，不同 PLGA/ACP 复合材料之间没有显著差异。然而，50%PLGA（65/35）与 50%ACP 的复合材料的降解速度略快于其他复合材料。形态上，所有支架表面在降解前从微孔多孔结构变为降解后两个月的波纹状固体微网状结构。基于体外结果，选择了涂有 65%PLGA（65/35）和 35%ACP 的支架，并将其植入大鼠主动脉（n=12）进行体内研究。显微镜观察显示，在植入后 12 周，任何植入的支架上均未发现复合材料，这表明所选的 PLGA/ACP 复合材料适合 DES 应用。
