Phenotypic variability in LQT3 human induced pluripotent stem cell-derived cardiomyocytes and their response to antiarrhythmic pharmacologic therapy: An in silico approach

Michelangelo Paci,Elisa Passini,Stefano Severi,Jari Hyttinen,Blanca Rodriguez

doi:10.1016/j.hrthm.2017.07.026

Michelangelo Paci, Elisa Passini + Show 3 more

Open Access

https://doi.org/10.1016/j.hrthm.2017.07.026

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Abstract

BackgroundHuman induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are in vitro models with the clear advantages of their human origin and suitability for human disease investigations. However, limitations include their incomplete characterization and variability reported in different cell lines and laboratories.ObjectiveThe purpose of this study was to investigate in silico ionic mechanisms potentially explaining the phenotypic variability of hiPSC-CMs in long QT syndrome type 3 (LQT3) and their response to antiarrhythmic drugs.MethodsPopulations of in silico hiPSC-CM models were constructed and calibrated for control (n = 1,463 models) and LQT3 caused by INaL channelopathy (n = 1,401 models), using experimental recordings for late sodium current (INaL) and action potentials (APs). Antiarrhythmic drug therapy was evaluated by simulating mexiletine and ranolazine multichannel effects.ResultsAs in experiments, LQT3 hiPSC-CMs yield prolonged action potential duration at 90% repolarization (APD90) (+34.3% than controls) and large electrophysiological variability. LQT3 hiPSC-CMs with symptomatic APs showed overexpression of ICaL, IK1, and INaL, underexpression of IKr, and increased sensitivity to both drugs compared to asymptomatic LQT3 models. Simulations showed that both mexiletine and ranolazine corrected APD prolongation in the LQT3 population but also highlighted differences in drug response. Mexiletine stops spontaneous APs in more LQT3 hiPSC-CMs models than ranolazine (784/1,401 vs 53/1,401) due to its stronger action on INa.ConclusionIn silico simulations demonstrate our ability to recapitulate variability in LQT3 and control hiPSC-CM phenotypes, and the ability of mexiletine and ranolazine to reduce APD prolongation, in agreement with experiments. The in silico models also identify potential ionic mechanisms of phenotypic variability in LQT3 hiPSC-CMs, explaining APD prolongation in symptomatic vs asymptomatic LQT3 hiPSC-CMs.

Highlights

In silico drug tests Effects of mexiletine and ranolazine at 5, 10, and 20 mM doses were assessed in silico on the control and mutant populations considering their multichannel effects on INa, INaL, the rapid delayed rectifying potassium current (IKr), and the L-type calcium current (ICaL) using the single pore block model, consistent with data from ion channel assays
The present study demonstrates the ability of populations of hiPSC-CMs in silico models to simulate and suggest potential mechanisms, which can be further tested in laboratory, underlying experimental variability in action potential (AP) of control and Long QT syndrome type 3 (LQT3) mutant cells observed in vitro, as well as their response to two antiarrhythmic blockers used in the treatment of LQT3 syndrome
We demonstrated the ability of computer simulations to capture and offer hypotheses for variability in LQT3 and control hiPSC-CM phenotype and in their response to mexiletine and ranolazine

Summary

Introduction

The LQT3 characteristic mechanism is the gain of function of the Na1 channels, which transport fast and late Na1 currents (INa and INaL, respectively). Such gain of function causes an Na1 inward leak during the action potential (AP), which prolongs its repolarization. Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are in vitro models with the clear advantages of their human origin and suitability for human disease investigations. Limitations include their incomplete characterization and variability reported in different cell lines and laboratories

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