Single Cell Multi-Omics of an iPSC Model of Human Sinoatrial Node Development Reveals Genetic Determinants of Heart Rate and Arrhythmia Susceptibility.

Defining the molecular and genetic basis for heart rate regulation and for susceptibility to atrial arrhythmias has been challenging due to the complexity of the human sinoatrial node (SAN), a tiny structure with limiting numbers of several distinct pacemaker cardiomyocyte (PC) subtypes in a spatially patterned array. Here we describe a novel method to derive large numbers of human PCs from human induced pluripotent stem cells (hiPSCs) that recapitulates key features of SAN development including differentiation into anatomically and functionally distinct PC subtypes of the SAN. Single cell (sc) RNA-sequencing, sc-ATAC-sequencing, and time course analyses of cellular differentiation were used to define epigenetic and transcriptomic signatures of cellular specialization within the SAN, and to identify transcriptional pathways important for PC differentiation. Intersection of our multi-omics datasets with existing human genome wide association studies uncovered regulatory elements with differential accessibility in different PC subtypes that harbored SNPs that associated with human heart rate regulation and susceptibility to atrial fibrillation, enabling disease gene discovery and prioritization.