ObjectiveTo research the magnetic labeled endothelial progenitor cells(EPCs) transplanted into the rat of venous thrombosis model through the tail vein and track transplanted stem cells in vivo, provide an effective monitoring technology for promoting organization and recanalization of deep venous thrombosis. MethodsBone marrowderived EPCs were extracted, purified, and identified, then labeled with the new SPIO particles. At the same time, the inferior vena cava thrombus models in rats were made, which were randomly divided into four groups:SPIO group (EPCs labeled with SPIO transplantation), Dil group (EPCs labeled with Dil transplantation), control group (simple EPCs transplantation), and blank control group (1 mL medium transplantation). After transplantation, the MRI, HE staining, and immunohistochemical staining were performed and the capillary density was counted under high-power microscope. ResultsThe MRI showed that EPCs labeled with SPIO had migrated to the inferior vena cava thrombus and the mass of high signal shade was seen, with the extension of time, the signal strengthened gradually. On day 14-21, the signal became the strongest, then decreased gradually. The immunohistochemical staining and HE staining showed that there were a mass of the new capillary in the specimens of thrombus of the SPIO group, Dil group, and control group, the difference was not statistically significant among these three groups(P > 0.05), but which was significant difference as compared with blank control group (P < 0.05). ConclusionCompared with EPCs labeled with Dil, it