KCNQ1-deficient and KCNQ1-mutant human embryonic stem cell-derived cardiomyocytes for modeling QT prolongation

Abstract BackgroundThe slowly activated delayed-rectifier potassium current (IKs) composed of KCNQ1 is one of the main currents in the process of repolarization. KCNQ1 mutation can lead to the occurrence of long-QT syndrome type 1 (LQT1). IKs does not participate in repolarization in mice; thus, no good model for the mechanism research and drug screening of LQT1 is currently available. In this study, we established a KCNQ1-deficient human cardiomyocyte (CM) model and performed a series of microelectrode array (MEA) detection using KCNQ1-mutant CMs constructed in other studies to explore the pathogenic mechanism of KCNQ1 deletion and mutation, and conduct drug screening.MethodKCNQ1 was knocked out in human embryonic stem cell (hESC) H9 line using the CRISPR/cas9 system. KCNQ1-deficient and KCNQ1-mutant hESCs were differentiated into CMs using a chemically defined differentiation protocol. Subsequently, high-throughput MEA analysis and drug intervention were performed to characterize the electrophysiological characteristics of KCNQ1-deficient and KCNQ1-mutant CMs.ResultsIn high-throughput MEA analysis, the electric field potential and action potential durations in KCNQ1-deficient CMs were significantly longer than those in wild-type CMs. KCNQ1-deficient CMs also showed an irregular rhythm. Furthermore, KCNQ1-deficient and KCNQ1-mutant CMs have different responses to different drug treatments, reflecting the differences in their pathogenic mechanisms.ConclusionWe established a human CM model with KCNQ1 deficiency, which showed prolonged QT interval and irregular heart rhythm. Simultaneously, we used various drugs to treat KCNQ1-deficient and KCNQ1-mutant CMs. The three models showed different responses to drugs. These models can be used as important tools for studying different pathogenic mechanisms of KCNQ1 mutation and the relationship between genotype and phenotype of KCNQ1, facilitating drug development.