cRGD-氧化铁纳米粒的构建及应用于核磁共振成像诊断中的动物研究

Construction of cRGD-iron oxide nanoparticles and its application in the tumor diagnosis by magnetic resonance imaging

目的:构建肿瘤靶向的核磁共振成像(magnetic resonance imaging,MRI)阴性造影剂纳米粒,并初步探讨其在肿瘤MRI中的应用。方法:化学共沉淀一步法制备超小型超顺磁性氧化铁(ultrasmall superparamagnetic iron oxide,USPIO)纳米粒。采用化学交联法将含有精氨酸-甘氨酸-天冬氨酸(Arg-Gly-Asp,RGD)序列的环形短肽(cyclic RGD,cRGD)与USPIO共价结合,制备具有整合素α靶向作用的超顺磁性造影剂,并对其进行理化性质的检测。采用普鲁士兰染色法检测cRGD-USPIO和USPIO与人肺腺癌A549细胞及人脐静脉内皮细胞(human umbilical vein endothelial cells,HUVECs)的特异性结合能力。建立A549裸鼠移植瘤模型,尾静脉注射USPIO和cRGD-USPIO,行MRI检测,评价cRGD-USPIO对肿瘤MRI信号增强的作用。结果:成功制备获得cRGD-USPIO纳米粒,其核心纳米粒径为5～10nm,平均粒径为(43.97±10.10)nm,比饱和磁化强度为59.94A.m2.kg-1。细胞结合实验结果提示,与USPIO组比较,cRGD-USPIO组阳性染色明显增强。动物体内MRI诊断结果显示,与USPIO组比较,cRGD-USPIO组肿瘤信号明显降低(P<0.01)。结论:构建的靶向性超顺磁性氧化铁纳米粒可能成为一种新型的、具有肿瘤早期诊断特异性的MRI阴性造影剂。

Objective：To construct superparamagnetic iron oxide nanoparticles targeting tumor angiogenesis and evaluate their potential value as contrast agent in magnetic resonance imaging（MRI）.Methods：Ultrasmall superparamagnetic iron oxide（USPIO） nanoparticles targeting tumor angiogenesis were prepared by using co-precipitation chemical method.Cyclic RGD（cRGD） containing the sequence of Arg-Gly-Asp were conjugated USPIO nanoparticles by using chemical conjugative method to prepare superparamagnetic imaging agent targeting tumor angiogenic vessles.The physical and chemical properties of cRGD-USPIO nanoparticles were detected.The specific binding capabilities of cRGD-USPIO and USPIO to human lung adenocarcinoma cells（A549） and human umbilical vein endothelial cells（HUVEC） were tested by Prussian blue staining.A549 xenografts were established in nude mice,then USPIO and cRGD-USPIO were injected though tail vein,and the MRI signal enhancement effect of cRGD-USPIO was evaluated.Results：We successfully prepared the cRGD-USPIO nanoparticles.Its core diameter was 5-10 nm and the average diameter was（43.97±10.10） nm and the quality saturation magnetic intensity was 59.94 A·m2·kg-1.Cell-binding test suggested that cRGD-USPIO group showed strengthened positive staining.In vivo MRI experiments showed that signals of tumor were significantly reduced in cRGD-USPIO group than that in USPIO group（P0.01）.Conclusion：The constructed cRGD-USPIO nanoparticles can be developed as a potential tumor-specific MRI contrast agent for the early diagnosis of cancer.