Induced Pluripotent Stem Cell – Derived Cardiomyocytes Elucidate Single-Cell Phenotype of Brugada Syndrome

Fro Ce pit Ha D Ins Ste HL J. rel Ma BACKGROUND Brugada syndrome (BrS), a disorder associated with characteristic electrocardiogram precordial ST-segment elevation, predisposes afflicted patients to ventricular fibrillation and sudden cardiac death. Despite marked achievements in outlining the organ level pathophysiology of the disorder, the understanding of human cellular phenotype has lagged due to a lack of adequate human cellular models of the disorder. OBJECTIVES The objective of this study was to examine single cell mechanism of Brugada syndrome using induced pluripotent stem cell–derived cardiomyocytes (iPSC-CMs). METHODS This study recruited 2 patients with type 1 BrS carrying 2 different sodium voltage-gated channel alpha subunit 5 variants as well as 2 healthy control subjects. We generated iPSCs from their skin fibroblasts by using integration-free Sendai virus. We used directed differentiation to create purified populations of iPSC-CMs. RESULTS BrS iPSC-CMs showed reductions in inward sodium current density and reduced maximal upstroke velocity of action potential compared with healthy control iPSC-CMs. Furthermore, BrS iPSC-CMs demonstrated increased burden of triggered activity, abnormal calcium (Ca2þ) transients, and beating interval variation. Correction of the causative variant by genome editing was performed, and resultant iPSC-CMs showed resolution of triggered activity and abnormal Ca2þ transients. Gene expression profiling of iPSC-CMs showed clustering of BrS compared with control subjects. Furthermore, BrS iPSC-CMgene expression correlatedwith gene expression fromBrS human cardiac tissue gene expression. CONCLUSIONS Patient-specific iPSC-CMs were able to recapitulate single-cell phenotype features of BrS, including blunted inward sodium current, increased triggered activity, and abnormal Ca2þ handling. This novel human cellular model creates future opportunities to further elucidate the cellular disease mechanism and identify novel therapeutic targets. (J Am Coll Cardiol 2016;68:2086–96) © 2016 by the American College of Cardiology Foundation. m the Stanford Cardiovascular Institute, Department of Medicine, Division of Cardiovascular Medicine, and Institute for Stem ll Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, California; The First Affiliated Hosal, Zhejiang University School of Medicine, Hangzhou, China; Institute of Translational Medicine, Zhejiang University, ngzhou, China; Department of Medicine, Division of Cardiology, University of California, San Francisco, California; and the epartment of Pharmacology, University of California, Davis, California. This study has received funding support from National titutes of Health (NIH) grant 5T32HL094274-04 (to Dr. Sallam); American Heart Association grant 13EIA14420025 and the ven M. Gootter Foundation (to Dr. J. Wu); and NIH grants R01 HL133272, NIH R01 HL126527, NIH R01 HL130020, and NIH R01 128170 (to Dr. J. Wu). Dr. Scheinman has received honoraria from St. Jude, Biosense Webster, Medtronic, and Biotronik. Dr. Wu has served on the scientific advisory board for Stem Cell Theranostics. All other authors have reported that they have no ationships relevant to the contents of this paper to disclose. Drs. Liang, Sallam, and H. Wu contributed equally to this work. nuscript received March 5, 2016; revised manuscript received June 29, 2016, accepted July 27, 2016. AB BR E V I A T I O N S