胶质瘤靶向嵌段共聚物体内外MR成像效果的实验研究

In vivo and in vitro MR imaging of glioma targeted block copolymer micelles

目的 探讨胶质瘤靶向嵌段共聚物胶束（ANPs/CPT）体内外MRI的效果.方法 构建ANPs/CPT,以1/T1对Gd3＋浓度作图拟合直线的斜率比较ANPs/CPT和二乙烯三胺五乙酸钆（DOTA-Gd）的纵向弛豫参数r1;将不同浓度的DOTA-Gd、非靶向嵌段共聚物胶束（NPs/CPT）、靶向嵌段共聚物胶束（ANPs/CPT）与C6细胞共培养,采用电感耦合等离子体发射谱（ICP-AES）分析细胞内Gd3＋元素含量;采用1.5 T MR分别测量不同含Gd3＋制剂MR信号强度（SI）、对比噪声比（CNR）;考察ANPs/CPT在正常大鼠脑、心、肝、肾等器官的对比噪声比（CNR）;采用胶质瘤大鼠模型观察ANPs/CPT在胶质瘤内的强化特征,计算肿瘤和正常脑组织信号比（T/N）及CNR.不同处理组间不同浓度Gd3＋摄入,C6细胞的SI、CNR,正常大鼠各器官的CNR,胶质瘤大鼠不同时间点上3组间T/N、CNR的比较采用单因素方差分析,差异有统计学意义后两两比较采用SNK法.结果 MR弛豫实验显示ANPs/CPT弛豫效率（13.900 s-1·mmol·L-1）约为DOTA-Gd（4.927 s-1·mmol·L-1）的3倍;C6细胞不同浓度Gd3＋摄入测定结果显示各组差异具有统计学意义（F值分别为362.502、1636.136、386.880、918.173,P值均〈0.001）,各组SI和CNR的差异也具有统计学意义（F值分别为55.240、155.419,P值均〈0.001）.正常大鼠尾静脉注射ANPs/CPT后显示脑组织的CNR在各个时间点与其他器官的差异具有统计学意义（F分别为9.417、21.808、21.383、107.318、178.762、P值均〈0.01）;胶质瘤大鼠模型注射ANPs/CPT组各时间点T/N（30 min后）、CNR与其余两组比较差异均有统计学意义（F值分别为5.349、6.594、24.078、18.508和6.840、6.780、5.895、12.620、37.139、368.893,P值均〈0.05）,两两比较差异也均有统计学意义（P值均〈0.05）.结论 ANPs/CPT具有良好的T1弛豫、长循环、胶质瘤靶向MRI的性能,为下一步研究胶质瘤可视化治疗提供了依据.

Objective To explore the in vivo/in vitro MR imaging effect of Angiopep2 modified glioma targeted block copolymer micelles（ANPs/CPT）. Methods Angiopep2 modified DOTA-Gd conjugated polymeric micelles based on beta-cyclodextrin（β-CD） were successfully synthesized.Water proton longitudinal relaxation rate （1/T1） were calculated to compare the r1of DOTA-Gd and ANPs/CPT. Different concentration of DOTA-Gd, NP/CPT, ANP/CPT were co-cultured with C6 cells, the intracellular content of Gd3＋was analyzed by ICP-AES;The signal intensity（SI） and contrast to noise ratio（CNR） were measured by 1.5 T MR;The CNR of ANPs/CPT was evaluated on different organs of normal rats. The enhancement feature of ANP/CPT in glioma as well as T/N and CNR between tumor and normal brain tissue were also investigated.Several comparisons were made between the 3 groups by one-way ANOVA,and the difference were significant when P〈0.05.Results The r1of ANPs/CPT（13.900 s-1·mmol/L-1）was 3 times as much as DOTA-Gd（4.927 s-1·mmol/L-1）.C6 cells uptake different concentrations of Gd3 ＋had significant difference among groups（F=362.502,1636.136,386.880,918.173, P〈0.001）.The difference of SI and CNR among groups were significant（F=55.240,155.419,P〈0.001）.The CNR of the brain tissue had significant difference with other organs at all times after tail vein injection of ANPs/CPT（F=9.417,21.808, 21.383,107.318,178.762,P〈0.01）.The ANPs/CPT showed excellent brain-targeting efficiency and theT/N ratio（30 min after）,CNR in different time point had significant difference among groups （F=5.349,6.594,24.078,18.508 and 6.840,6.780,5.895,12.620,37.139,368.893, P〈0.05）.Conclusions ANPs/CPT shows nice agnetic relaxation performance,extended blood circulation duration,excellent brain-targeting efficieney, which will render the theranosticnano-carriers with important reference for the construction of new generation multifunctional nanomedicine.