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[Magnetic resonance imaging of magnetically labeled endothelial progenitor cells homing to the injured endothelium].

OBJECTIVE
Accumulating evidence suggests that the endothelial progenitor cells (EPCs) can reendothelialization the injured endothelium. Superparamagnetic iron-oxide particles are being used for intracellular magnetic labeling of cells and in vivo cells tracking. The aim of this study was to investigate the possibility of depict and track magnetically labeled EPCs in vivo for carotid artery endothelium injured New Zealand White rabbit model by 1.5 T magnetic resonance imaging system after EPCs transplantation.


METHODS
The EPCs of New Zealand White rabbit were isolated, confirmed, expanded and then incubated with home synthesized Fe2O3-PLL for 24 hours, Prussian blue stain was performed for showing intracellular irons. The model of carotid arterial injury was performed by 2.5 F balloons. The group A of 5 rabbits were transplanted with magnetically labeled EPCs, the group B of 5 rabbits were received fluorescent-labeled EPCs, and 5 rabbits of the group C were received the same volume of saline injection immediately after the carotid artery endothelium was injured. The transfused EPCs were strictly restricted to the injury site. MR imaging and histology were performed and compared 7 days late.


RESULTS
The Epcs labeling efficiency of Fe2O3-PLL was more than 95% identified by Prussian blue stain. Seven days after the transplanted of EPCs, only in group A, the injured endothelium of carotid artery wall had the signal intensity loss in T(2)WI MRI, which corresponding to the injured endothelium where the most Prussian blue staining-positive cells were in histopathological analyses. While histopathological slides showed that the fluorescence-positive cells in the injured endothelium which had been transplanted Dil labeled EPCs also. The group C was either in negative.


CONCLUSION
The rabbits endothelial progenitor cells can be effectively labeled with Fe2O3-PLL, 1.5 T magnetic resonance imaging system could depict and monitor the magnetically labeled endothelial progenitor cells homing to the injured endothelium of the artery, which may have much more potential values for studying the engraftment of EPCs in cardiovascular disease.