[Cell therapy and arrhythmias: state of the art].

Cell therapy is an adjunctive treatment to improve left ventricular function after myocardial injury. Multiple cell types have been tested experimentally in animal models of myocardial disease, with functional improvement as the primary endpoint. Regarding safety, the major concern has been that cell transplantation could generate an arrhythmogenic substrate as reported in clinical studies using myoblasts. The mechanism of these transplantation-related arrhythmias remains elusive but the cellular heterogeneity, resulting from differences in electrical membrane properties between recipient/donor cells, could provide a substrate for reentry circuits. The knowledge achieved from experimental studies on the substrate of arrhythmias in cell therapy gives useful information that could be translated into the development of a biological pacemaker or a non-pharmacological approach to atrial fibrillation. Limitations of current pharmacological and catheter ablation options to achieve rate control in patients with atrial fibrillation have motivated new strategies of cell therapy for non-pharmacological rate control without producing high-degree atrioventricular block. Although several issues remain to be addressed, some aspects of cell therapy are likely to be translated into clinical practice.