From the Cover: High-Throughput Imaging of Cardiac Microtissues for the Assessment of Cardiac Contraction during Drug Discovery

Abstract

Cardiotoxicity is a common cause of attrition in preclinical and clinical drug development. Current in vitro approaches have two main limitations, they either are limited to low throughput methods not amendable to drug discovery or lack the physiological responses to allow an integrated risk assessment. A human 3D cardiac microtissue containing human-induced pluripotent stem cell-derived cardiomyocytes (hiPS-CMs), cardiac endothelial cells and cardiac fibroblast were used to assess their suitability to detect drug induced changes in cardiomyocyte contraction. These cardiac microtissues, have a uniform size, spontaneously beat, lack a hypoxic core, and contain key markers of each cell type. Application of field stimulation and measurement of cardiac contraction confirm cardiac microtissues to be a suitable model to investigate drug-induced changes in cardiomyocyte contractility. Using a bespoke image acquisition work flow and optical flow analysis method to test 29 inotroptic and 13 non-inotroptic compounds in vivo We report that cardiac microtissues provide a high-throughput experimental model that is both able to detect changes in cardiac contraction with a sensitivity and specificity of 80 and 91%, respectively, and provide insight into the direction of the inotropic response. Allowing improved in vitro cardiac contractility risk assessment. Moreover, our data provide evidence of the detection of this liability at therapeutically relevant concentrations with a throughput amenable to drug discovery.

Characterization and Validation of a Human 3D Cardiac Microtissue for the Assessment of Changes in Cardiac Pathology

“…This is the first study reporting the use of a large, diverse panel of different structural cardiotoxin drug classes in combination with an advanced cardiac in vitro model assessing cardiac structure. Studies to date in advanced cardiac models have assessed cardiac function, primarily profiling a small number of compounds 35 , 39 , 40 or specific functional acute alterations 41 . Our data suggests that the combination of imaging parameters and assessment of cellular viability in cardiac microtissues can predict the in vivo outcome of structural cardiotoxins (change in cardiac morphology or clinical biomarker release) with an overall sensitivity of 73% and specificity of 86%.…”

“…Previous studies investigating structural cardiotoxicity identified the importance of the use of an in vitro model that was actively contracting 18 . As these cardiac microtissues have a higher spontaneous beat rate 41 , it could also be hypothesized that the increased contraction, and thus energy utilization, increases the sensitivity to perturbations and that small modifications in the cellular ATP pool could potentially have a greater impact on cellular health in cells with a higher basal beat rate.…”

Machine Learning of Human Pluripotent Stem Cell-Derived Engineered Cardiac Tissue Contractility for Automated Drug Classification

“…While the concept of examining multiple parameters from waveforms has been pursued lately, some studies have suggested that only a few select parameters (e.g., peak count) are necessary in assessing a compound's cardioactivity as other parameters provide no further mechanistic insight ( Lu et al., 2015 , Pointon et al., 2016 , Sirenko et al., 2013 ). This is primarily true when the hPSC-CMs are spontaneously beating, meaning the force generated is linked to beating frequency.…”

Mechanobiology Assays with Applications in Cardiomyocyte Biology and Cardiotoxicity

“…Several labs have deployed advanced video microscopy analyses of drug‐induced changes in contractile function of hiPSC‐CMs, from single cells to 3D tissue constructs. [ 91,98,108,114–116 ] Common mechanical readouts include changes in peak contraction/relaxation amplitudes, contraction/relaxation velocities, and beat rate (Table 2). For example, Sala et al deployed their “MUSCLEMOTION” analysis software to study the cardiotoxic agent Nifedipine (a Ca 2+ channel blocker used to treat hypertension) and learn that it reduces contraction amplitudes in single‐cell hiPSC‐CM, hiPSC‐CM monolayers, and 3D tissue constructs.…”