BS-454195-3 GENERATION OF A NOVEL IN-VITRO MODEL OF THE INFARCT BORDER ZONE TO STUDY HUMAN VENTRICULAR ARRHYTHMIAS

Abstract

Sudden cardiac death (SCD), the majority of which is due to ventricular arrhythmias (VA). It is thought that post-myocardial infarction VA results from the presence of slowly conducting viable strands at the infarct border zone (IBZ), forming the basis for reentry We aimed to develop an in-vitro anatomical model of the IBZ to study VA. To this end, we combined advanced micropatterning and human-induced pluripotent stem cell-derived cardiomyocyte (hiPSC-CMs) technologies hiPSC-CMs were differentiated into ventricular cells and seeded in a 2D simplified micropatterned model of IBZ. The model was created using a DMD-based maskless photolithography system (Primo). The process involves coating a culture dish with a combination of anti-fouling materials that block protein connections to the plate, a photoinitiator gel, and laser patterning of the pre-designed micro-pattern. The plate is then coated by ECM and hiPSC-CMs to generate the desired tissue geometry. Optical mapping during pacing from different sites was used to characterize the conduction properties in the model and the impact of geometry on arrhythmogenesis (Fig.1) We designed a simplified series of models of a compact scar to model VA arising at the IBZ . This model includes surviving cardiomyocyte strands within the scar. In the structural inhomogeneity group, we added a narrowing within the surviving conducting fiber (n= 18, Fig.1a), whereas the control specimens did not include any narrowing (n=12). The presence of structural inhomogeneity was found to facilitate the incidence of uni-/bi- directional conduction blocks (18/18 in the narrowing vs. 8/12 in controls, P<0.01), which also occurred at lower pacing frequencies (2.2±0.2Hz vs. 3.7±0.17Hz, P<0.001, Fig.1c-l, 2). The development of uni-directional conduction block facilitated the development of reentrant arrhythmias in the model (Fig.1e-i), with the arrhythmias developing at a greater propensity in the narrowing group (6/7 vs. 2/7, p<0.05). Repolarization analysis [action potential duration 80% (APD80) maps] showed a homogenous repolarization pattern in the model (mean APD80 standard deviation: 10±6 ms) The novel in-vitro model of the IBZ highlighted the role of structural inhomogeneities in the development of conduction blocks and reentrant arrhythmias, most probably due to source/sink mismatches, this new experimental approach may bring unique value to the study of the mechanisms and treatments of cardiac arrhythmias