Electrophysiologic implications of myocardial stem cell therapies

Myocardial stem cell therapies are emerging as exciting new experimental strategies for treatment of a variety of cardiovascular disorders. This review describes the electrophysiologic implications associated with these emerging strategies. The electrophysiologic considerations associated with cell therapy for myocardial infarct repair are described from the mechanistic point of view (assessing electromechanical coupling between donor and host cells) and from the therapeutic (possibly preventing malignant ventricular arrhythmias) and potential adverse effects (increasing arrhythmogenesis) points of view. The potential of different stem cell therapy approaches for the treatment of bradyarrhythmias, are discussed. Such therapy includes efforts to generate biologic pacemakers either by genetically modifying mesenchymal stem cells to overexpress the pacemaker current I(f) or by inducing differentiation of human embryonic stem cells into cardiomyocytes having pacemaking properties. The ability of cell therapy using genetically modified cells to modulate the electrophysiologic substrate in an attempt to treat different tachyarrhythmias is described. The potential advantages and shortcomings of each strategy are discussed, as are the obstacles that must be overcome before these exciting strategies can become a clinical reality.