超顺磁性氧化铁标记反义寡脱氧核苷酸探针在转染细胞磁共振成像中的应用

Application of Superparamagnetic Iron Oxide Labeled Antisense Oligodeoxynucleotide Probe in Cellular Magnetic Resonance Imaging

目的制备超顺磁性氧化铁(SPIO)标记的反义寡脱氧核苷酸(ASODN)探针,探讨其应用于转染细胞磁共振(MR)成像的可行性。方法采用化学交联法将SPIO标记于c-erbB2癌基因的ASODN制成ASODN探针,原子力显微镜检测探针形态,高效液相凝胶色谱法检测联接率和生物活性,聚丙烯酰胺凝胶电泳法检测稳定性。将ASODN探针转染高表达c-erbB2癌基因的SK-Br3肿瘤细胞株,普鲁士蓝染色后于光学显微镜下观察细胞内铁分布,原子吸收光谱法测定细胞内铁含量,MR扫描观察细胞信号强度变化情况。结果制备的ASODN探针近似球形,粒径在25～40nm间,分散均匀,联接率为100%,仍保持原有生物活性,稳定性好。转染ASODN探针后的SK-Br3细胞胞浆内可见多少不等的蓝色铁颗粒,细胞内铁含量明显高于未转染ASODN探针的其他各组细胞(P均<0.01);MR扫描显示其信号强度最弱,信噪比值明显低于其他各组细胞(P均<0.05)。结论成功制备SPIO标记ASODN探针,该探针能有效进入SK-Br3细胞内,明显降低MR扫描下的转染细胞信号强度。

Objective To prepare the superparamagnetic iron oxide （SPIO） -labeled antisense oligodeoxynucleotide （ASODN） probe and evaluate the application of this probe in cellular magnetic resonance imaging （MRI）. Methods We prepared the SPIO-labeled ASODN probe using chemical cross linking method to conjugate SPIO to ASODN, detected its configuration by atomic force microscopy, determined the conjugating rate and biology activation by high performance liquid chromatography, and detected the stability by polyacryl- amide gel electrophoresis. After that, we transfected the SK-Br3 oncocytes which had over-expression of the c-erbB2 oncogene by this probes, observed the intracellular iron distribution by optical microscope, measured iron content by atomic absorption spectroscopy, and observed the signal change by MRI. Results Atomic force microscope showed that the SPIO-labeled ASODN probe was mostly spherical and well-distributed, with a diameter of 25-40nm and a conjugating rate of 100%. This probe had inhere biological activity and stability. In addition, light microscopy revealed an intracellular uptake of iron oxides in the transfected SK-Br3 oncocyte, and the iron content of the group of transfected SK-Br3 oncocytes was significantly higher than those of other contrast groups （all P 〈 0.01 ）. MRI shomed that transfected SK-Br3 oncocyte had the lowest signal among all other cells （ all P 〈 0.05 ）. Conclusions We prepared the SPIO-labeled ASODN probe successfully. It can effectively transfect SK-Br3 oncocyte and enter SK-Br3 oncocyte, and thus reduce the signal intension in MRI.