Cell transplantation and echocardiography

MI was induced by permanent ligation of the left anterior descending (LAD) coronary artery in immunodeficient (RNU rats, Charles River)/immunocompetent rats (Brown Norway, Charles River) (weight: 160–220 g). Briefly, heart was exposed via a left thoracotomy, and the proximal LAD was ligated. One million cells were suspended in 100 μL vehicle (IMDM-base media without any essential nutrients or growth factors) and injected into the myocardium at 4 sites adjacent to the infarct while IMDM serves as placebo control. Baseline echocardiograms were acquired 1 day after procedure (post-operative echocardiographic examinations at 24 h to insure similar extend of induction of MI), 7 days and at 28 days post- MI. Two-dimensional and M-mode echocardiography was performed using the VisualSonics Vevo 2100 ultrasound unit (VisualSonics, Toronto, Canada) to assess metrics of left ventricular size and function. Images were obtained from the parasternal long axis and the parasternal short axis at the midpapillary level.