OBJECTIVETo analyze the stem cell re-distribution after intra-coronary infusion (ICI) into arrested and beating hearts in a swine myocardial infarction (MI) model using magnetic resonance imaging (MRI).

METHODSBone marrow-derived mesenchymal stem cells were obtained from male swine and labeled with iron oxide during culture. One week after MI in female swine, the survivors were randomly divided into 4 groups. Cardiopulmonary bypass was set up to arrest the heart, and then SPIO labeled male stem cells (1 × 10(8)) were infused through coronary of beating heart (n = 6) and the arrested heart (n = 6). Saline was injected in either the beating or arresting heart as respective controls. Three days later, cell distribution was assessed by T2(*) change with magnetic resonance imaging and Y-chromosome (SRY) was detected with quantitative polymerase chain reaction.

RESULTSThe reduction of T2(*) values was significantly different in the hearts, spleens, livers and lung between the transplantation groups and the control groups. Only few transplanted cells were localized in the heart and T2(*) values were similar between beating and arrest heart groups [(-7.81 ± 2.03) ms vs. (-6.56 ± 1.72) ms, P > 0.05], while T2(*) value reduction was more significant in the spleen and liver in arrest heart group than in beating heart group [spleen: (-16.72 ± 2.83) ms vs. (-22.18 ± 3.98) ms, P < 0.01, liver: (-2.40 ± 0.44) ms vs. (-5.32 ± 3.40) ms, P < 0.05]. T2(*) value was similar in kidney among the four groups. qRT-PCR detected SRY gene was similar in the heart, less in the spleen and liver while more in the lung in beating heart group compared to arrested heart group. In vitro Prussian blue stained positively transplanted cells were found in the above organs in transplantation group.

CONCLUSIONSThe majority of stem cells transplanted by ICI would be entrapped by the extracardiac organs. Stem cell transplantation via ICI into the arrested heart does not favor more cells retention in the injured myocardium. Further investigation is needed to optimize the approach of stem cell delivery.