Abstract 949 Deciphering the pathogenic role of a variant with uncertain significance for short QT and Brugada syndrome using gene-edited induced pluripotent stem cell-derived cardiomyocytes and drug screening

Clin Res Cardiol (2022). https://doi.org/10.1007/s00392-022-02002-5
Deciphering the pathogenic role of a variant with uncertain significance for short QT and Brugada syndrome using gene-edited induced pluripotent stem cell-derived cardiomyocytes and drug screening
I. El-Battrawy¹, H. Lan², L. Cyganek³, L. Maywald², R. Zhong², F. Zhang², X. xu⁴, Q. Xu², J. Li⁵, E. Duperrex⁶, J. Lee⁶, A. Hierlemann⁶, A. M. Saguner⁷, F. Duru⁷, B. Kovacs⁷, M. Huang², Z. Liao², S. Albers², H. Dinkel², Y. Li², M. Kleinsorge⁸, S. Lang², A. Mügge⁹, A. Aweimer¹, X. Fan², S. Diecke¹⁰, I. Akin², G. Li¹¹, X. Zhou²
¹Medizinische Klinik II, Kardiologie und Angiologie, Berufsgenossenschaftlliches Universitätsklinikum Bergmannsheil, Bochum; ²Universitätsklinikum Mannheim, Mannheim; ³Herzzentrum Göttingen - Stem Cell Unit, Universitätsmedizin Göttingen, Göttingen; ⁴Medizinische Klinik und Poliklinik II, Universitätsklinikum Bonn, Bonn; ⁵Institut für Biochemie und Molekulare Medizin, Universität Bern, Bern, CH; ⁶Bioengineering Laboratory, Department of Biosystems Science and Engineering, ETH Zürich, , Basel, CH; ⁷Unispital Zürich, Zürich, CH; ⁸Herzzentrum, Klinik für Kardiologie und Pneumologie, Universitätsmedizin Göttingen, Göttingen; ⁹Medizinische Klinik II, Kardiologie, Klinikum der Ruhr-Universität Bochum, Bochum; ¹⁰MDC Berlin, Berlin; ¹¹Institute of Cardiovascular Research, Southwest Medical University, Luzhou, CN;
Background: Short QT (SQTS) and Brugada (BrS) syndrome are rare channelopathies causing sudden cardiac death (SCD). Investigations of human cellular phenotypes and effective therapies of SQTS and BrS linked to CACNB2 variants remain sparse. Aims: The aim of this study was to assess the pathogenic roles of a CACNB2 variant of uncertain significance for SQTS and to search for possible effective drugs for treatment of the disease and underlying pathomechanism by using patient-specific and CRISPR-engineered human-induced pluripotent stem cell–derived cardiomyocytes (hiPSC-CMs). Methods: hiPSC-CMs from a patient with SQTS type 5 (SQT5) overlapping with BrS carrying a variant in the CACNB2 gene (dbSNP rs121917812; NM_000724.4: c.1439C>T/p.S480L), from two independent healthy donors, from an isogenic cell line with variant-correction (using CRISPR/Cas9) and a further cell line with variant-insertion (using CRISPR/Cas9) were employed for this study. Patch-clamp, field potential, Ca²⁺ imaging and molecular studies were applied. Results: Comparing with hiPSC-CMs from the healthy donors, cells from the SQT5-patient (SQT5-hiPSC-CMs) displayed abnormal action potentials (APs) with a shortening in the action potential and field potential duration (APD) and a reduction of Vmax, resulting from a loss of function of L-type calcium and sodium channels. The occurrence of arrhythmic events (abnormal spontaneous calcium transients and APs) was increased in SQT5-hiPSC-CMs, indicating that the SQT5-hiPSC-CMs recapitulated phenotypic changes of SQTS and BrS. CRISPR-correction of the variant rescued the phenotypic changes, whereas insertion of the variant in a healthy iPSC line provoked phenotypic changes, which confirmed the genotype-phenotype correlation. Sotalol failed to prolong the APD and suppress arrhythmias. Quinidine and amiodarone prolonged APD. Quinidine showed a slight, but amiodarone showed a significant antiarrhythmic effect. PI3K and Akt expression was downregulated in SQT5 cells, while IGF-1, a PI3K activator, rescued the SQT5 phenotype changes. Conclusions: The CACNB2 variant c.1439C>T/p.S480L is linked to the clinical phenotype of SQT5 overlapped with BrS. The PI3K pathway may contribute to arrhythmogenesis of the disease. PI3K activator and amiodarone but not sotalol may be effective drugs for treating arrhythmias in SQT5-patients or patients with overlap of SQT5 and BrS caused by CACNB2 variants.
https://dgk.org/kongress_programme/jt2022/aV600.html

Background: Short QT (SQTS) and Brugada (BrS) syndrome are rare channelopathies causing sudden cardiac death (SCD). Investigations of human cellular phenotypes and effective therapies of SQTS and BrS linked to CACNB2 variants remain sparse.