Optogenetic Control of Repolarization Gradients in Human Induced Pluripotent Stem Cell Derived Cardiac Tissue
2Cardiology Department Rambam Health Care Campus, Haifa, Israel
Background:
Changes in cardiac action-potential (AP) morphology and spatial distribution can increase risk of arrhythmia. We used optogenetic tools to shape AP morphology in-vitro in human cardiac-tissue, creating a novel model for the investigation of dispersion of repolarization in arrhythmogenesis.
Methods:
Engineered-HEK293 cells expressing light-sensitive cationic channel (CoChR) were co-cultured with human induced pluripotent stem-cell-derived cardiomyocytes (hiPSC-CMs). Optical mapping was used to monitor electrical activity of the generated co-cultures. A digital micro-mirror device was used to apply complex illumination-patterns with high spatiotemporal resolutions.
Results:
Optogenetic stimulation during APs allowed modulation of AP duration (APD) in co-cultures by ~30-50%. Moreover, we produced APD gradients within the tissue by using specific light-patterns (Fig.1A). Steeper APD gradients significantly increased the likelihood of arrhythmogenesis (Fig.1B). APD prolongation of 80, 130 and 180ms in selected areas lead to spiral wave induction in 7%, 15% and 39% of experiments respectively, compared to 0% in experiments without APD modulation. Further, the time window in which premature S2 stimulation induced reentry was increased when steeper APD gradients were generated. Next, we created tissues with innate APD gradients by seeding cardiomyocytes from healthy-control hiPSCs next to short-QT syndrome CMs. This led to spiral wave induction in 61±13% of co-cultures. Using optogenetic stimulation to homogenize the APD within the tissue, the rate of arrhythmogenesis was reduced to 11±7%.
Conclusion:
Optogenetic intervention can be used to shape AP morphology in human cardiac-tissue models. This allowed us to investigate the role of local repolarization gradients in promoting arrhythmogenesis and develop novel optogenetic-based anti-arrhythmic treatments focused on repolarization homogenization.