Abstract 16707: Human Embryonic Stem Cell-Derived Cardiomyocytes Are Safe and Improve Infarct Size and Cardiac Function in a Porcine Model of Myocardial Infarction

Introduction: Stem cell therapy is an emerging means of stimulating cardiac repair after myocardial infarction (MI). Human embryonic stem cell-derived cardiomyocytes (hESC-CMs) are a novel therapeutic option, with the potential for cell derived remuscularization. This study assessed the safety and efficacy of these cells, is the first to test these cells in a porcine model of MI, and used electrophysiologic (EPS) testing to evaluate potential arrhythmogenicity. Methods: Yucatan swine underwent a left anterior descending coronary artery ischemia/reperfusion protocol to form an MI. Four weeks later, either placebo (n=3) or 3 x 10 8 hESC-CMs were delivered via transendocardial stem cell injection (TESI) (n=4). All animals received immunosuppression for 2 weeks following TESI. Three uninfarcted animals received cells. Cardiac function and LV chamber volumes were measured using pressure volume catheterization and cardiac MRI at 4, 8 and 12 weeks post-TESI. Inducibility of ventricular tachycardia (VT) was tested at 4 and 12 weeks post-TESI by programmed ventricular stimulation via a catheter in the RV apex. Histology of heart tissue and organs was evaluated. Results: Twelve weeks post-TESI, scar size (scar mass as a % of total LV mass) was reduced in the cell treated group by -2.33±0.03% (p=0.034), a 12.69±1.87% reduction from pre-TESI. Scar size remained constant in the placebo group. The rise in end diastolic volume at 12 weeks in the placebo group (15.6±7.35 mL; p=0.032) was attenuated in the cell treated group (10.39±6.36mL; p=0.17). By 12 weeks post-TESI, Ees (slope of ESPVR) increased by 0.51±0.15 mmHg/mL (p=0.045) and in the cell treated group but was unchanged in placebo (-0.09±0.85 mmHg/mL; p= 0.92). Following TESI, only 1 animal from each group had inducible VT. No animals had spontaneous VT as measured by an implantable loop recorder. Cardiac function and structure of uninfarcted animals did not change over the study, and none of these animals had inducible VT. Histology did not reveal ectopic tissue formation or signs of rejection. Conclusion: TESI of hESC in a porcine MI model is safe, does not increase the risk of either spontaneous or inducible arrhythmias compared to placebo, reduces scar size and remodeling and improves cardiac contractility as measured by Ees. Translation to clinical studies is warranted.