Development of a pro-arrhythmic ex vivo intact human and porcine model: cardiac electrophysiological changes associated with cellular uncoupling

Joseph Brook,Siân E Harding ,A Jothidasan ,Nicholas S Peters ,Konstantinos N Tzortzis ,Anil A Bharath ,Simos Koutsoftidis,Justin Perkins,David S Pitcher ,Surani Ma ,Xinyang Li,C.n.j Jenkins ,Fu Siong Ng,Annam Sufi,Danya Agha-Jaffar ,Ji‐Jian Chow ,Richard J Jabbour,Chris D Cantwell ,C Stuart Houston ,Balvinder S Handa,Poppy Bristow,Minyoung Kim ,Rasheda A Chowdhury

doi:10.1007/s00424-020-02446-6

Abstract

We describe a human and large animal Langendorff experimental apparatus for live electrophysiological studies and measure the electrophysiological changes due to gap junction uncoupling in human and porcine hearts. The resultant ex vivo intact human and porcine model can bridge the translational gap between smaller simple laboratory models and clinical research. In particular, electrophysiological models would benefit from the greater myocardial mass of a large heart due to its effects on far-field signal, electrode contact issues and motion artefacts, consequently more closely mimicking the clinical setting. Porcine (n = 9) and human (n = 4) donor hearts were perfused on a custom-designed Langendorff apparatus. Epicardial electrograms were collected at 16 sites across the left atrium and left ventricle. A total of 1 mM of carbenoxolone was administered at 5 ml/min to induce cellular uncoupling, and then recordings were repeated at the same sites. Changes in electrogram characteristics were analysed. We demonstrate the viability of a controlled ex vivo model of intact porcine and human hearts for electrophysiology with pharmacological modulation. Carbenoxolone reduces cellular coupling and changes contact electrogram features. The time from stimulus artefact to (-dV/dt)max increased between baseline and carbenoxolone (47.9 ± 4.1–67.2 ± 2.7 ms) indicating conduction slowing. The features with the largest percentage change between baseline and carbenoxolone were fractionation + 185.3%, endpoint amplitude − 106.9%, S-endpoint gradient + 54.9%, S point − 39.4%, RS ratio + 38.6% and (-dV/dt)max − 20.9%. The physiological relevance of this methodological tool is that it provides a model to further investigate pharmacologically induced pro-arrhythmic substrates.

Highlights

Ex vivo modelsHertfordshire AL97TA, UKA major challenge for translational research in the cardiovascular field is to effectively and efficiently translate research from bench to bedside
We aimed to demonstrate the utility of the intact ex vivo porcine and human heart as a model for high fidelity, controlled electrophysiological studies with acute pharmacological modulation
We have demonstrated the development of an acute pathological model in the intact ex vivo human heart

Summary

Introduction

Ex vivo modelsHertfordshire AL97TA, UKA major challenge for translational research in the cardiovascular field is to effectively and efficiently translate research from bench to bedside. In vitro and small animal disease models in particular are limited in their recapitulation of the human phenotype, with only a third of small animal research studies resulting in positive translation to human randomised trials [13]. Cell and small animal models are still an absolute necessity in disease characterisation and safety assessment before scaling up. This is due to their ability to control confounding factors and their relative simplicity. Cell models lack the myocardial mass to represent the effects found in intact preparations, whilst smaller animal models are anatomically and physiologically less comparable with the clinic than large animals. Full characterisation and validation of cellular factors and mechanistic insight cannot be obtained

Objectives

Methods

Results

Conclusion