LAUSR

The sinoatrial node (SAN) is the primary pacemaker of the heart. The human SAN is poorly understood due to limited primary tissue access and lack of robust in vitro derivation methods. We developed an efficient strategy, using a dual SHOX2:GFP; MYH6:mCherry knock-in reporter line, to generate and purify human pluripotent stem cell-derived SAN cells (hPSC-SAN), displaying molecular and electrophysiological characteristics of bona-fide nodal cells. We modeled cell type specific toxicity upon treatment with doxorubicin (DOXO) using hPSC-SAN generated from a library of induced pluripotent stem cells (iPSCs). We discovered 3 new genetic loci associated with increased sensitivity to DOXO-induced hPSC-SAN death. Genetic variants in these loci were associated with significantly higher early arrhythmia risk in patients receiving DOXO, confirmed by an unbiased PheWAS analysis. Finally, the in vitro DOXO assay enabled an unbiased drug screening platform and identification a candidate therapeutic that can partially block DOXO-mediated cardiac toxicity.