Abstract P1031: An Optogenetic Approach To Study Atrial-fibrillation-associated Remodelling In Atrial Engineered Human Myocardium

Abstract

Background: Atrial fibrillation (AF) is the most common clinically reported arrhythmia. It is associated with electrophysiological and structural alterations that promote the maintenance of the disease. The limited longevity of human cardiac samples has historically restricted mechanistic investigation into these remodeling processes of human atrial cardiomyocytes and has hampered antiarrhythmic-therapy development. Objective: We aim to assess if classical AF-associated remodeling events can be elicited in atrial engineered human myocardium (EHM) constructed from atrial subtype-specific induced pluripotent stem cell derived cardiomyocytes (iPSC-CM). Methods: To allow for long-term optical tachypacing at 3 Hz (TP), EHM were generated from cells expressing the light-gated ion-channel f-Chrimson (CRISPR-Cas9 technique). 24-hour or 7 day TP was applied to EHMs. Action potentials (AP) were acquired using the sharp microelectrode impaling technique. Results: 24-hour TP of atrial EHMs resulted in action potential shortening (APD 90 : 215.7±4.9 vs. 243.7±7.3, P <0.01) compared to EHMs paced at 1 Hz. In addition, TP attenuated the response to the M-receptor agonist carbachol. Resting membrane potential was unaffected. In order to more closely simulate persistent AF (clinically diagnosed after 7 consecutive days of AF events), 7 day TP was applied to the EHMs. Similar to 24 hour TP, this produced AP shortening and a blunted response to M-receptor agonists. Interestingly, this also led to hyperpolarization of the resting membrane potential (RMP: -75.1±0.8 vs. -72.5±0.8, P <0.05) compared to EHMs paced at 1 Hz. Conclusion: Classical characteristics of AF-associated remodeling were elicited through TP of EHM. This unique optogenetic technique represents the first in vitro model to investigate the time-dependence of cellular AF-associated remodeling in the long-term. This offers immense potential for drug development studies and personalized approaches for antiarrhythmic therapy.