Recellularized Humanized Bioengineered Biatrial Model for Arrhythmia, Biological Pacemakers, and Optogenetic Studies.

Abstract

The study of atrial arrhythmias has been hampered by the lack of anatomically relevant human cardiac tissue models and by the inability to perform targeted, functional perturbations in such models. To engineer anatomically relevant light-sensitive atrial chambers, we combined human pluripotent stem cells, differentiation protocols yielding atrial and sinoatrial nodal cells, rat heart decellularization/recellularization processes, and optogenetics tools. Immunostaining for chamber-specific cardiomyocyte markers, optical action potential recordings, and the response to atrial-specific pharmacology confirmed the atrial-specific identity of the recellularized engineered tissue. Histological examination verified the preservation of the macroscopic and microscopic atrial architecture of the engineered atria. Optical mapping showed the ability of seeded human pluripotent stem cell-derived sinoatrial nodal cells at the correct anatomic site to serve as a biological pacemaker. Adenoviral transduction and transgenic human pluripotent stem cells were used to express the light-sensitive channels, ChR2 (channelrhodopsin-2) or CoChR (<i>Chloromonas oogama</i> channelrhodopsin), in the bioengineered atria, allowing optogenetic pacing and programmed stimulation. Reentrant arrhythmias could be induced and optically mapped in the bioengineered atrial tissue models, demonstrating the ability to recapitulate and provide insights into different atrial fibrillation mechanisms. These arrhythmias could be terminated by localized (focal or linear) or diffused optogenetic silencing (optogenetic cardioversion). A novel, light-controllable, bioengineered humanized biatrial tissue model was established and could be used to model different atrial arrhythmias, for drug testing, for disease modeling, and for evaluation of novel therapeutic interventions such as biological pacemaking and optogenetic interventions.