Objective: To investigate the feasibility of labeling endothelial progenitor cells (EPCs) with a novel dual modal contrast agent Molday IONTM EverGreen(MIEG) and its performance in vitro MRI.
Methods: EPCs were isolated from rat bone marrow and labeled with 10, 20, 50 μg/mL MIEG, respectively. The labeling rates were identified by Prussian blue staining and fluorescence microscopy. The vitality of EPCs labeled with 20 μg/mL MIEG was detected by trypan blue exclusion test at 1 d, 1 w, 2 w, and 6 w after labeling. EPCs labeled with different concentrations of MIEG were scanned by 3.0T MRI with T1 weighted and T2 weighted imaging.
Results: The labeling rates for EPCs labeled with different concentrations of MIEG were greater than 98%,and the cytoplasm of labeled EPCs was present with Prussian blue staining. Although the green lighting level went down, the labeling rate at 6 w after labeling was greater than 90%. Trypan blue exclusion test showed that there was no significant difference in the vitality between EPCs labeled with MIEG at 1 d, 1 w, 2 w and 6 w after labeling and EPCs without labeling (all P>0.05). There was no difference in signal intensity on T1 weighted image among EPCs labeled with different concentrations of MIEG. However, the signal intensity on T2 weighted image was reduced in all labeled groups, and the signal reduction became more apparent with increased concentration of MIEG.
Conclusions: EPCs can be effectively labeled by MIEG without interference on the cell viability at the labeled concentration of 20 μg/mL. The signal intensity change of labeled cells can be detected sensitively by T2 weighted imaging at 3.0T MRI.
目的: 探讨用双模态对比剂Molday ION TM EverGreen（MIEG）标记大鼠骨髓来源内皮祖细胞（EPC）及其行磁共振扫描的可行性。
方法: 以铁的终浓度为10、20、50 μg/mL的MIEG对大鼠骨髓来源EPC进行磁性和荧光双标记，普鲁士蓝染色及荧光镜下观察细胞标记情况，比较不同浓度MIEG标记EPC后的标记阳性率；台盼蓝染色检测20 μg/mL MIEG标记EPC后1 d及1、2、6周时细胞的活性，并应用3.0T磁共振扫描仪对不同浓度标记的细胞行T 1、T 2序列扫描。
结果: MIEG标记EPC后细胞标记率高达98%以上，标记6周后绿色荧光强度有一定程度降低，但荧光标记率仍达90%以上；普鲁士蓝染色显示铁颗粒位于细胞质内。台盼蓝染色结果显示，20 μg/mL MIEG标记EPC对其细胞活性无明显影响（均 P>0.05）。体外磁共振扫描结果显示，不同浓度MIEG标记的EPC T 1信号强度无明显差异，T 2信号强度随MIEG浓度增加而降低。
结论: 20 μg/mL MIEG标记EPC为适宜的标记浓度，不仅能够高效标记EPC，而且不会影响EPC的细胞活性。磁共振成像体外扫描T 2序列可敏感地发现不同浓度MIEG标记EPC后信号强度变化。