缓释碱性成纤维细胞生长因子微球在兔膝关节液内的降解和释药性质

Degradation and drug release characteristics of basic fibroblast growth factor sustained release microspheres in knee joints of rabbits

背景:聚乳酸-羟基乙酸共聚物包封碱性成纤维细胞生长因子制备的缓释微球在体外磷酸盐缓冲液中能持续释放活性碱性成纤维细胞生长因子。目的:观察碱性成纤维细胞生长因子微球在兔关节不同功能状态下关节滑液内局部降解、释药动力学规律。设计、时间及地点:完全随机分组设计的动物实验,于2006-04/2007-03在四川大学建筑与环境学院生物力学工程实验室完成。材料:81只成年新西兰大白兔。采用复乳法优化处方制备碱性成纤维细胞生长因子-聚乳酸-羟基乙酸共聚物微球。方法:81只兔按随机数字表法分为4组,微球组(n=36),碱性成纤维细胞生长因子组(n=27),微球组兔双膝关节内注射150mg碱性成纤维细胞生长因子微球(含62.25μg碱性成纤维细胞生长因子)+0.6mL生理盐水,右膝半屈曲位固定,为微球固定组;左膝不固定,为微球活动组。碱性成纤维细胞生长因子组兔双膝关节内注射62.25μg游离碱性成纤维细胞生长因子+0.6mL生理盐水,右膝半屈曲位固定,为碱性成纤维细胞生长因子固定组;左膝不固定,为碱性成纤维细胞生长因子活动组。空白对照组9只,兔双膝关节内注射0.6mL生理盐水,不固定。空白微球组9只,兔双膝关节内注射150mg空白聚乳酸-羟基乙酸共聚物微球+0.6mL生理盐水,不固定。主要观察指标:于术后1,2,4,6,8,10,12,14,16d采集标本,观察关节液中碱性成纤维细胞生长因子微球形态变化及释药变化,聚乳酸-羟基乙酸共聚物微球载体材料分子质量变化。结果:微球组在关节液内可持续稳定释放碱性成纤维细胞生长因子10d以上,碱性成纤维细胞生长因子组4d后关节液内未检测到碱性成纤维细胞生长因子。降解14d后,微球活动组球形完全消失,已降解成为一些碎片;微球固定组部分降解成为无定形样物,部分微球的球形仍在。在降解过程中,聚乳酸-羟基乙酸共聚物的重均分子质量不断减小。微球活动组在各时相点重均分子质量均低于微球固定组,差异均有显著性意义(P<0.05)。结论:碱性成纤维细胞生长因子缓释微球在置于关节腔内后可稳定释药,关节运动可加快微球的降解和释药速度。

BACKGROUND： Poly（lactic-co-glycolic-acid） （PLGA） microspheres may continuously release basic fibroblast growth factor （bFGF） in phosphate buffer solution in vitro. OBJECTIVE： To explore the characteristic of bFGF microspheres in the joint fluid through the experiments of biodegradation and drug release in the knee joints of rabbits. DESIGN, TIME AND SETTING： The randomized control animal experiment was carried out in the Biomechanical Engineering Laboratory, College of Architecture and Environment, Sichuan University （Chengdu, Sichuan, China） from April 2006 to March 2007. MATERIALS： A total of 81 New Zealand white rabbits were used in this study. The microspheres were prepared using the bFGF-PLGA by W/O/W multiple emulsion evaporation method with the optimized formulation. METHODS： Eighty-one rabbits were divided into four groups randomly： microsphere group （n =36）, bFGF group （n =36）, blank microsphere group （n =9） and blank control group （n=9）. Rabbits of the microsphere group were injected with 150 mg microspheres containing 62.25 μ g bFGF plus 0.6 mL saline. Then those fixed at a half flexion in right knees were taken as the micrphere fixation group, while those remaining unfixed in left knees served as the microphere active group. Rabbits of the bFGF group were injected 62.25 μ g free bFGF plus 0.6 mL saline and then assigned to two groups with the same grouping as that of microphere group. Blank control group and blank microsphere group were only injected with 0.6 mL saline or 150 mg microspheres containing 62.25 μ g bFGF plus 0.6 mL saline, without the process of fixation. MAIN OUTCOME MEASURES： The specimens were collected at postoperative 1, 2, 4, 6, 8, 10, 12, 14 and 16 days. The changes of the morphous and drug release of bFGF microspheres in joint fluid were detected, as well as the molecular mass of PLGA carriers. RESULTS： In the microsphere group, the bFGF microspheres could continuously release bFGF more than 10 days in the joint fluid, while no bFGF could be detected in the joint fluid after 4 days in the free bFGF group. The trend of biodegradation of bFGF microspheres in the joint fluid was greater after 14 days. The molecular loss of PLGA was found during the process of degradation, and the weight-average molecular mass in the microsphere active group was significantly lower than that in the microsphere fixation group （P 〈 0.05）. CONCLUSION： The bFGF-PLGA microspheres can continuously release bFGF effectively in the joint fluid, the velocity of biodegradation and drug release in joint fluid would be quickened with the movement of joint.