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DOI: 10.1055/s-2006-925671
Tissue distribution of radiolabeled bone marrow cells after intramyocardial transplantation in pigs with myocardial infarction
Objective: To evaluate the biodistribution of transplanted mononuclear bone marrow cells (MNC) after radiolabeling with Indium (In)-111 in a big animal myocardial infarction (MI) model.
Methods: MI was induced in 7 male domestic pigs (28–32kg) by catheter guided coil occlusion of the LAD. Two weeks later, autologous MNCs were injected into the infarcted area via left thoracotomy. In 3 animals MNCs were labeled with In-111 and scintigraphic images were acquired up to 48h after cell administration. In 4 animals MNCs were labeled with Hoechst dye and colloidal gold for histological analysis 2, 4 and 8 weeks after cell injection.
Results: The amount of radioactivity in the heart remained stable and was about 85% during the first 30min, 85% at 2h, 79% at 24h and 77% at 48h after cell injection. Tracer distribution slightly increased from 5% to 7% in the lungs and from 4% to 11% in the liver. Radioactivity of kidneys, spleen and peripheral skeletal muscle tissue was less than 5% at all time points. In histology, grafted cells were readily identified, some were longitudinal in shape and adjacent to cardiomyocytes. However, most cells were monocyte- or macrophage-like in morphology. They stained positive for p-connexin and CD45, but not for alpha-actinin.
Conclusions: In-111-labeling is suitable to follow cells after transplantation. There is evidence for high grafting efficacy and persistence of MNCs after needle injection into infarcted myocardium. Despite prompt histological identification of transplanted cells for up to 8 weeks no evidence for myocardial differentiation was found.