MR imaging of injected magnetically labeled stem cells in myocardial infarction: experiment with pigs

Abstract

To investigate the efficacy of magnetic resonance imaging (MRI) in tracking bone marrow derived mononuclear cells (BM-MNCs) labeled with superparamagnetic iron oxide (SPIO) nanoparticles. BM-MNCs were isolated from the bone marrow of 14 pigs. These 14 pigs underwent occlusion of the left anterior descending coronary artery (LAD) to establish myocardial infarction (MI) models and then randomly divided into 2 groups: experimental group (n = 9) to be injected with BM-MNCs labeled with SPIO intracoronarily under X-ray fluoroscopy, and control group (n = 5), to be injected with unlabelled BM-MNCs MRI was performed with a 1.5T MR scanner to demonstrate the location of the BM-MNCs once a week. T pigs were killed when no labeled BM-MSC was detected. The hearts were taken out to undergo HE staging and Prussian blue staining. Immunohistochemistry was used to detect the desmin and myosin. The cell labeling efficiency was almost 100%. Contrast-enhanced MRI demonstrated successful establishment of MI models. Effective MRI tracking findings were obtained in 8 pigs, 7 of the experimental group and 3 of the control group. In 3 pigs T2* weighted MRI showed the zone of labeled cell accumulation shows vague low-signal area around the infarction area and much better conspicuity of the zone of hypoenhancement was shown under contrast-enhanced MRI. The hypoenhancement zone disappeared 14 - 21 days after the injection of BM-MSCs. Histological analyses showed that most Prussian blue positive cells were well correlated with the area where a signal intensity loss was observed in MRI. 1.5T MR imaging can monitor the magnetically labeled BM-MNC in vivo in myocardial infarction provided the number of injected is nor less than 10(6).