Engraftment of human embryonic stem cell derived cardiomyocytes improves conduction in an arrhythmogenic in vitro model

► We show electrophysiological benefits of cells from beating embryoid bodies (EBs). ► An in vitro model with abnormal conduction is used in which the cells are engrafted. ► Cells from beating EBs help to normalize conduction and reduce reentrant arrhythmia. ► Cells from non-beating EBs do not improve conduction. ► The mechanism for improvement appears to be via heterocellular electrical coupling.