Abstract 13258: Transcriptomic Remodeling of Brugada Syndrome Arises During in vitroCardiac Development

Introduction:Recent genetic data suggest that abnormal cardiac development participate to the pathogenesis of Brugada Syndrome (BrS), a rare inherited arrhythmia responsible for sudden cardiac death in young adults. In vitrocardiac differentiation of human induced pluripotent stem cells (hiPSCs) mimics cardiac development at the cellular level up to a prenatal stage.Objective:This study aims at defining whether BrS impairs cardiac differentiation of hiPSCs.Methods & Results:Transcriptomic kinetics (daily bulk 3’RNA-seq from day 0 to day 30 of in vitro cardiac differentiation) were generated in triplicate for 2 control hiPSC lines and 2 BrS-patient hiPSC lines. First, global analysis unveiled that BrS and control kinetics start to diverge as early as day 8, coinciding with the emergence of beating cells. The 500 most differentially expressed genes between BrS and control kinetics revealed 7 main distinct expression profiles. Interestingly, in one of the clusters (Cluster 2), enriched in genes involved in ventricular development (e.g. IRX4, NKX2-5), the expression levels were higher in BrS as compared to control, starting at day 8. Inversely, another cluster (Cluster 4), enriched in genes involved in atrial development (e.g. TBX18, PITX2), displayed an opposite expression profile. Cell-type annotation of single-cell RNA-seq data obtained at day 30 of cardiac differentiation for 1 control (n=2; 11,499 cells) and 1 BrS hiPSCs line (n=2; 12,142 cells) confirmed this ventricular-to-atrial imbalance with an average ventricular-to-atrial cell number ratio of 0.97 and 8.27 for control and BrS lines, respectively.Conclusion:This first transcriptomic kinetic study supports the hypothesis of an early developmental defect in BrS. Altogether, our data show that BrS hiPSCs are more prone to ventricular specification as compared to control cells. This suggests that an abnormal cell fate during cardiac differentiation may participate to BrS pathogeny.