局部重复应用控释BCNU聚乳酸微球治疗U251胶质瘤的实验研究

 目的研究局部重复应用聚乳酸[poly(D,L-lactic acid),PLA]控释卡莫司汀[1,3-bis(2-chlorethyl)-1-nitrosourea,BCNU]微球(BCNU-PLA)对U251人脑胶质瘤的生长抑制作用。方法应用沉淀方法制备包载BCNU的PLA纳米微球。应用扫描电子显微镜观察载药微球形态,分别应用Bratton-Marshall比色法和紫外分光光度法测定微球载药率与药物释放曲线。应用MTT方法检测PBS、BCNU、PLA微球和BCNU-PLA等不同处理方法对U251胶质瘤细胞增殖活性的影响。应用U251裸鼠皮下移植瘤模型为研究对象,连续3次进行PBS、BCNU、PLA微球和BCNU-PLA的治疗,观察实验动物的生存期与皮下肿瘤生长情况。结果扫描电子显微镜观察载药纳米微球呈球形,具有良好的单分散性;BCNU-PLA平均粒径为23.5μm。BCNU-PLA平均载药率为11.5%;以相对分子质量30×10³的PLA制备BCNU-PLA微球的体外药物释放分析显示:BCNU在释放开始的10d表现出较大的突释,释放量达到载药量的40%;随后进入控释期,至4周左右释放了所载药物的50%。与BCNU原药治疗组比较,BCNU-PLA控释微球治疗在体外持续抑制U251胶质瘤细胞的生长;在体内明显抑制裸鼠皮下荷U251胶质瘤的生长,并显著改善荷瘤鼠的全身状况。结论BCNU-PLA载药微球可有效抑制皮下荷U251胶质瘤的生长,是局部化疗治疗胶质瘤的一种新策略。

Growth Inhibition Against U251 Gliomas by Repeated Local Administration of BCNU from Controlled Release Poly(D,L-Lactic acid) Microspheres

OBJECTIVE To study the inhibitory effects of local administration of BCNU-loaded poly(lactic acid) microspheres BCNU-PL on U251 human gliomacells.METHODS BCNU-PLA was prepared with nano-precipitation technology.Scanning electronic microscope was used to profile the morphologyl of microspheres.Bratton-Marshall colorimetric method and spectrophotometry were used respectively to determine the drug loading and release behavior.The proliferative activities of U251 glioma cells treated by PBS,PLA microspheres,BCNU and BCNU-PLA were measured by MTT respectively.The subcutaneous U251 glioma model in nude mice was used to evaluate the anti-tumor effect of repeated administration of BCNU-PLA.RESULTS The resulting particles were fractured and showed the characteristic alveolar morphology.The average particle size was 23.5 μm for BCNU-PLA.The drug loading was 11.5% w/w.Drug release behavior in vitro indicated the burst effect was high(40%) after incubation for 10 d.50% Accumulated release was observed after sustained release for 4 weeks.In vitro study indicated BCNU-PLA exerted sustained inhibition effect up to 6 d compared with BCNU administration.In vivo study demonstrated significant anti-tumor effect had been achieved by repeated local administration of BCNU-PLA and general condition of tumor-bearing mice was improved.CONCLUSION The BCNU-PLA can inhibite the growth of subcutaneous U251 gliomas,thus will be a good stratagy of local chemotherapy of gliomas.