[Rat endothelial progenitor cells labeled with Molday ION^TM EverGreen and in vitro MRI study]

To investigate the feasibility of labeling endothelial progenitor cells (EPCs) with a novel dual modal contrast agent Molday ION^TM EverGreen(MIEG) and its performance in vitro MRI.

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.

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.

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.