Abstract 15754: Genetically Engineered Stem Cell-Derived Model for Therapeutic Discovery in Long QT Syndrome

Abstract

Introduction: Long QT syndrome (LQTS) is caused by delayed ventricular repolarization and is a cause of sudden death. In a recent chemical screen with an in vivo zebrafish model of LQTS-type 2, we identified 2-methoxy-N-[4-methylphenyl] benzamide (2MMB), which shortens the ventricular action potential (Figure A). Methods: We initially used a zebrafish LQT2 model to perform a structure-activity relationship (SAR) study with 50 substituted benzanilide derivatives. We generated a human LQT-type 1 embryonic stem cell (hESC) model with a bi-allelic disruption of KCNQ1 in the hESC H7 line using CRISPR. KCNQ1-/- hESC-derived cardiomyocytes (hESC-CM) were electrophysiologically characterized and used to perform secondary structure activity studies for a subset of benzanilide derivatives (Figure A). Results: We observed a range of biological activities among the 50 analogs tested in the zebrafish assay, including several compounds with no activity and several that were more potent than 2MMB. Genetically engineered LQT1 hESC-CMs had diminished IKs current (Figure B) and prolonged action potentials that significantly shortened upon 2MMB treatment (Figure C). SAR studies in the LQT1 hESC-CMs confirmed improved potency for two of the compounds and lack of activity for one. A single discrepancy existed for a compound without activity in our zebrafish assay but significantly shortened action potentials in hESC-CMs. Conclusions: We report the use of a physiologically faithful genetically engineered LQT1 hESC line for therapeutic discovery in LQTS. Inclusion of hESC-CMs in future studies may complement animal testing by enabling direct screening on disease specific human tissue.