Swine experimental model to evaluate stem cell implant post myocardial infarction by Perfusion Gated-SPET.

Autologous bone marrow stromal cells (BMSC) implant after swine experimental myocardial infarct (MI) was investigated by serial technetium-99m ((99m)Tc)-tetrofosmin gated single photon emission tomography (G-SPET) and compared with immuno-histochemical findings. The aim was to evaluate if intramyocardial BMSC implant produces any prolonged effect in the left ventricle (LV) perfusion and function. Eleven pigs underwent left anterior descending artery (LAD) ligature; in seven of them BMSC were injected in the border zone of the MI, while in the remaining four saline solution was injected at the same site. After LAD ligature G-SPET scans at 48h and at 5 and 10 weeks (w) after the implant were performed. Uptake defect size and LV function analysis were performed comparing 48h to 5w and 10w studies. Statistical evaluation was performed with Friedman test and unpaired Wilcoxon test. The comparison between a progressive reduction of Perfusion Image Score was observed from 48h to 5w and to 10w in the treated group (Friedman test: χ²= 13.56; P=0.01). No variation was observed in the control group (Friedman test: χ²=3; P= 0.223). Comparison of the absolute variation (Δ) between treated and control group resulted significant (Wilcoxon test W=10; P=0.007). Similar positive results were also observed for the relative extension of the uptake defect, wall motion and LVEF analysis. Histological data of our swine model demonstrated that autologous BMSC implanted in the damaged myocardium area had survived and differentiated into cells with typical features of myocardiocytes. Gated SPET is a reliable tool to evaluate prolonged positive effects of autologous BMSC implant in swine experimental MI model. In conclusion, autologous BMSC implanted can improve perfusion, induce cell regeneration, reduce wall motion abnormalities and prevent severe LV dysfunction in swines