多孔聚乳酸-聚乙醇酸共聚物作为缓释重组人骨形态发生蛋白-2载体的实验研究

目的 探讨多孔聚乳酸-聚乙醇酸共聚物(PLGA)作为重组人骨形态发生蛋白-2(rhBMP-2)的载体，通过体外释放试验和体内活性试验来评价rhBMP-2释放的动力学过程及活性。方法 采用乳液冷冻干燥法制作含rhBMP-2缓释系统的PLGA支架，支架进行扫描电镜观察；采用高效液相色谱分析仪检测不同时间点释放液中rhBMP-2的含量，进行累积释放量的动态观察；将缓释rhBMP-2支架植入SD大鼠大腿股部肌袋内，分别在不同时间点进行组织学观察。结果 支架材料的形态学观察显示，材料表面呈多孔状；rhBMP-2从支架中释放的动力学过程为第1天表现为爆发性释放(30.0％)，以后缓慢持续释放，至1个月左右释放量达80.6％；活性评价结果显示，rhBMP-2缓释支架组可见新生骨组织形成伴较多的骨母细胞排列，无rhBMP-2支架组则无成骨现象。结论 多孔PLGA可作为rhBMP-2的缓释载体，并具有良好的生物活性，可作为骨组织工程研究中的新型支架，同时具有临床应用的可行性。

Experimental study on porous poly (DL-lactic-co-glycolic acid) as carrier for sustained release of the recombinant human bone morphogenetic protein-2

Objective To assess the feasibility of porous poly (DL lactic co glycolic acid) (PLGA) scaffold as carrier for controlled release of recombinant human bone morphogenetic protein 2 (rhBMP 2) and evaluate the release kinetics and the activity of rhBMP 2 through in vitro release test and in vivo activity assessment. Methods The PLGA scaffolds with rhBMP 2 sustained release system were made by emulsion freeze dried method and observed with scanning electron microscope. The released rhBMP 2 content from polymer was dynamically observed using high performance liquid chromatography at various set times. Meanwhile, the curve of cumulative rhBMP 2 release kinetics was created. The scaffold loaded with rhBMP 2 and the simple scaffold were implanted bilaterally into ectopic muscle pouches of SD rat so as to observe bone formation histologically. Results The surface of the scaffold was with multipore. An initial burst release (30.0%) of the incorporated rhBMP 2 was observed over the first day followed by a sustained release for the remainder, which reached 80.6% at one month. The rhBMP 2 activity assessment showed that new bone was formed with osteoblasts in experimental group but that there was no bone formation in control group. Conclusion With good osteogenetic activity, the porous PLGA can be served as carrier for sustained release of rhBMP 2 and as new type of scaffold in bone tissue engineering and has potential in clinical application.