Electrophysiological consequence of adipose-derived stem cell transplantation in infarcted porcine myocardium

Aims Aim of this study was to investigate the effect of intraccronary administration of freshly isolated adipose-derived mononuclear cells (ADMCs) on myocardial vulnerability to arrhythmia induction after infarction. Methods and results A transmural myocardial infarction in an experimental porcine model was induced by occlusion of the mid-left anterior descending artery with an angioplasty balloon for 3 h. Upon reperfusion, a cellular suspension with freshly isolated ADMCs (1.5 x 10(6) cells/kg BW) or vehicle alone was injected into the infarct artery. All animals underwent a programmed ventricular stimulation at 8 weeks follow-up for possible induction of ventricular arrhythmias using a train of 8 S1 stimuli. Cell injections did not cause acute ventricular arrhythmia, bradycardia, or conduction block. The cycle length of the ventricular arrhythmia was compared at 1 and 10 s following its induction. Despite comparable infarct size in both groups, we found that the cycle length of the induced ventricular arrhythmia in the ADMC-treated group was significantly longer compared with control animals (P < 0.05). We also found that extrastimuli were required for arrhythmia induction in the ADMC-treated group compared with control animals. Conclusion Freshly isolated autologous stem cell therapy is not proarrhythmic in pigs.