外加磁场对SPIO-shRNA分子探针用于活体荷瘤裸鼠卵巢癌肿瘤MR成像的影响

Effects of external magnetic field on MR imaging of ovarian tumor in nude mice bearing tumor by SPIO-shRNA molecular probe

摘要:

目的：探讨外加磁场对SPIO-shRNA分子探针用于活体荷瘤裸鼠卵巢癌肿瘤MR成像的影响。方法：设定探针注射浓度为含铁18 mg/kg，扫描时间为探针注射后27 h；将30只BALB/c荷瘤裸鼠随机分为3组，即磁转染组（实验组），探针转染组（阴性对照组），荷瘤裸鼠组（空白对照组），每组样本量分别为10只荷瘤裸鼠，并在扫描前对磁转染组行外加磁场处理。采用磁共振MR扫描检测裸鼠体内肿瘤组织及邻近肌肉组织信号强度变化；每次检查完成后立即处死裸鼠，取出肿瘤组织及肌肉组织行HE、普鲁士蓝染色，并在光学显微镜下观察。结果：T1WI序列各组间肿瘤组织信号强度差异不具有统计学意义（F=2.623，P=0.091），各组间肌肉组织信号强度差异不具有统计学意义（F=0.434，P=0.652）；T2WI及T2*序列磁转染组及探针转染组肿瘤组织信号强度较荷瘤裸鼠组减低，差异具有统计学意义（P=0.000），且磁转染组较探针转染组差异更显著，差异具有统计学意义（P=0.000）；而T2*序列磁转染组肌肉组织信号强度较其余组信号减低，差异具有统计学意义（P=0.000）；HE染色显示各组肿瘤组织结构紊乱，细胞核异型性增多；普鲁士蓝染色表明在磁转染组和探针转染组中均存在蓝染铁颗粒，且磁转染组蓝染颗粒更为丰富。结论：外加磁场能够诱导SPIO-shRNA分子探针靶向作用于卵巢癌肿瘤组织并提高肿瘤组织摄取

Abstract:

Objective：To investigate the effect of external magnetic field on MR imaging of ovarian tumor in nude mice bearing tumor in vivo by SPIO-shRNA molecular probe. Methods：The concentration of probe injection was set as iron 18 mg/kg，and the scanning time was 27 h after probe injection. BALB/c mice of 30 were randomly divided into 3 groups，namely magnetic transfection group （experimental group），SPIO-shRNA group（negative control group），nude mice bearing cancer group（control group）. Sample capacity of each group was 10 and the experimental group was magnetic transfected before scan. Changes of signal intensity in tumor tissue and adjacent muscle tissue were scanned by magnetic resonance imaging（MRI）. The nude mice were killed after that treatment，tumor and muscle tissues were sampled for HE and prussian blue stain and observed under optical microscope. Results：The difference of tumor tissue signal intensity of T1WI sequence among three groups was not statistically significant（F=2.623，P=0.091） and the differ－ence of muscle tissue signal intensity in each group was not statistically significant（F=0.434，P=0.652）. Compared with those in the control group，the tumor tissue signal intensity of T2WI and T2* sequence in the experimental group and the negative control group were decreased，with statistically significant differences（P=0.000），and compared with that in the negative control group，it was more significantly in experimental group with statistically significant differences（P=0.000）. Compared with that in the other groups，the T2* sequence of muscle tissue signal intensity in the experimental group was relatively lower，with statistically significant difference（P=0.000）. HE staining showed that structure of tumor tissue was abnormal and nuclear atypia was increased；prussian blue staining showed that blue-stained iron particles existed in both experimental group and negative control group，with more in the experimental group. Conclusion：The external magnetic field can induce SPI－O-shRNA molecular probes target to ovarian tumor tissues and increase the effective concentration of tumor tissue absorption.