Abstract 13067: Recapitulating Long QT Syndrome Phenotype in Induced Pluripotent Stem Cells-Derived Cardiomyocytes Using CRISPR/Cas9 Technology

Introduction: Long QT syndrome (LQTS) is an inherited arrhythmia syndrome with a hallmark of QT prolongation secondary to delayed repolarization of cardiomyocytes (CM) on 12-lead ECG. Hypothesis: Studying LQTS in an induced pluripotent stem cell (iPSC)-derived CM model allows for patient-specific phenotype characterization in vitro . We report such a strategy (fig. A) in a patient with LQT type 3 (ECG QTc 503 msec) who harbored a heterozygous pathogenic variant in SCN5A (c.1231G>A), and in a healthy control for comparison (ECG QTc 388 msec). Methods: IPSCs were generated from patient and control dermal fibroblasts using a non-integrational Sendai reprogramming method. The patient’s SCN5A (c.1231G>A) variant was edited into the healthy control using CRISPR/Cas9 technology. CM were subsequently differentiated and beating CM clusters were seeded onto Maestro CytoView multi-electrode array plates. Serial corrected field potential duration (FPD) measurements (n=12), equivalent to QTc values on ECG, were recorded on days 24 to 39 of CM differentiation per sample. CM were exposed to varying concentrations of Nifedipine and Sotalol through cell culture media exchange. Paired t-tests (non-parametric) were utilized for p<0.05. Results: Reprogrammed iPSCs displayed pluripotency characteristics (fig.B). IPSC-derived CMs had confirmed cardiac lineage (fig. C). Prolonged FPD values, corrected for beating rate, were observed in both the LQT3 patient-derived iPSC-CMs (p<0.0001) and the genetically induced LQT3 iPSC-CMs (p<0.0001) compared to control (fig. D & E). Nifedipine and sotalol altered FPD in a dose-dependent response (fig. F & G). Conclusions: An iPSC-derived CM model reliably recapitulates the phenotype of LQTS. Induced LQT3 iPSC-CMs genetically edited from a healthy control accurately recapitulate the LQT3 disease phenotype. Drug effects on CM repolarization were demonstrable in the iPSC-CM model.