© 2016 Toma et al. Background: A novel MRI technique, employing dual contrast manganese-enhanced MRI (MEMRI) and delayed enhancement MRI (DEMRI), can evaluate the physiologically unstable peri-infarct region. Dual contrast MEMRI-DEMRI enables comprehensive evaluation of telmisartan to salvage the peri-infarct injury to elucidate the underlying mechanism of restoring the ischemic cardiomyopathy in the diabetic mouse model. Methods and results: Dual contrast MEMRI-DEMRI was performed on weeks 1, 2, and 4 following initiation of telmisartan treatment in 24 left anterior descendent artery ligated diabetic mice. The MRI images were analyzed for core infarct, peri-infarct, left ventricular end-diastolic, end-systolic volumes, and the left ventricular ejection fraction (LVEF). Transmission electron microscopy (TEM) and real-time PCR were used for ex vivo analysis of the myocardium. Telmisartan vs. control groups demonstrated significantly improved LVEF at weeks 1, 2, and 4, respectively (33 ± 7 %*** vs 19 ± 5 %, 29 ± 3 %*** vs 22 ± 4 %, and 31 ± 2 %*** vs 18 ± 6 %, ***p < 0.001). The control group demonstrated significant differences in the scar volume measured by MEMRI and DEMRI, demonstrating peri-infarct injury. Telmisartan group significantly salvaged the peri-infarct injury. The myocardial effects were validated by TEM, which confirmed the presence of the injured but viable cardiomyocyte morphology in the peri-infarct region and by flow cytometry of venous blood, which demonstrated significantly increased circulating endothelial progenitor cells (EPCs). Conclusion: The improved cardiac function in ischemic cardiomyopathy of diabetic mice by telmisartan is attributed to the attenuation of the peri-infarct injury by the angiogenic effects of EPCs to salvage the injured cardiomyocytes. Dual-contrast M EMRI-DEMRI technique tracked the therapeutic effects of telmisartan on the injured myocardium longitudinally.
Toma, I., Kim, P. J., Dash, R., McConnell, M. V., Nishimura, D., Harnish, P., & Yang, P. C. (2016). Telmisartan in the diabetic murine model of acute myocardial infarction: Dual contrast manganese-enhanced and delayed enhancement MRI evaluation of the peri-infarct region. Cardiovascular Diabetology, 15(1). https://doi.org/10.1186/s12933-016-0348-y