The Potential Mechanisms behind Loperamide-Induced Cardiac Arrhythmias Associated with Human Abuse and Extreme Overdose.

Loperamide has been a safe and effective treatment for diarrhea for many years. However, many cases of cardiotoxicity with intentional abuse of loperamide ingestion have recently been reported. We evaluated loperamide in in vitro and in vivo cardiac safety models to understand the mechanisms for this cardiotoxicity.

High-Throughput Screening Assay for Detecting Drug-Induced Changes in Synchronized Neuronal Oscillations and Potential Seizure Risk Based on Ca Fluorescence Measurements in Human Induced Pluripotent Stem Cell (hiPSC)-Derived Neuronal 2D and 3D Cultures.

Drug-induced seizure liability is a significant safety issue and the basis for attrition in drug development. Occurrence in late development results in increased costs, human risk, and delayed market availability of novel therapeutics. Therefore, there is an urgent need for biologically relevant, in vitro high-throughput screening assays (HTS) to predict potential risks for drug-induced seizure early in drug discovery.

Is the forming of neuronal network activity in human-induced pluripotent stem cells important for the detection of drug-induced seizure risks?

Background: Functional network activity is a characteristic for neuronal cells, and the complexity of the network activity represents the necessary substrate to support complex brain functions. Drugs that drastically increase the neuronal network activity may have a potential higher risk for seizures in human. Although there has been some recent considerable progress made using cultures from different types of human-induced pluripotent stem cell (hiPSC) derived neurons, one of the primary limitations is the lack of - or very low - network activity.

Identifying Acute Cardiac Hazard in Early Drug Discovery Using a Calcium Transient High-Throughput Assay in Human-Induced Pluripotent Stem Cell-Derived Cardiomyocytes.

Early identification of cardiac risk is essential for reducing late-stage attrition in drug development. We adapted the previously published cardiac hazard risk-scoring system using a calcium transient assay in human stem cell-derived CMs for the identification of cardiac risks recorded from the new hiPSC-CM line and investigated its predictivity and translational value based on the screening of a large number of reference and proprietary compounds. Evaluation of 55 reference drugs provided the translation of various pharmacological effects into a single hazard label (no, low, high, or very high hazard) using a Ca-sensitive fluorescent dye assay recorded by -by FDSS/µCell Functional Drug Screening System (Hamamatsu on hiPSC-CM line (FCDI iCell Cardiomyocytes).

Comparison of the Simulated Response of Three Human Stem Cell-Derived Cardiomyocytes Models and Data Under 15 Drug Actions.

Improvements in human stem cell-derived cardiomyocyte (hSC-CM) technology have promoted their use for drug testing and disease investigations. Several hSC-CM models have been proposed to augment interpretation of experimental findings through simulations. This work aims to assess the response of three hSC-CM models (Koivumäki2018, Kernik2019, and Paci2020) to simulated drug action, and compare simulation results against data for 15 drugs.

The resting membrane potential of hSC-CM in a syncytium is more hyperpolarised than that of isolated cells.

Human-induced pluripotent stem cell (hiPSC) and stem cell (hSC) derived cardiomyocytes (CM) are gaining popularity as in vitro model for cardiology and pharmacology studies. A remaining flaw of these cells, as shown by single-cell electrophysiological characterization, is a more depolarized resting membrane potential (RMP) compared to native CM. Most reports attribute this to a lower expression of the Kir2.

Utility of Normalized TdP Score System in Drug Proarrhythmic Potential Assessment: A Blinded in vitro Study of CiPA Drugs.

Drugs that prolong QT may cause torsade de pointes (TdP). However, translation of nonclinical assessment of QT prolongation or hERG channel, targeted by QT-prolonging drugs, into clinical TdP risk has been insufficient to date. In this blinded study, we confirmed the utility of a Normalized TdP Score System in predicting drug-induced TdP risks among 34 drugs, including 28 with low, intermediate, and high TdP risks under the Comprehensive In Vitro Proarrhythmia Assay (CiPA) initiative plus six compounds with names blinded to the investigators, using the rabbit ventricular wedge assay.

Hit-to-lead optimization and discovery of a potent, and orally bioavailable G protein coupled receptor kinase 2 (GRK2) inhibitor.

G-protein coupled receptor kinase 2 (GRK2), which is upregulated in the failing heart, appears to play a critical role in heart failure (HF) progression in part because enhanced GRK2 activity promotes dysfunction of β-adrenergic signaling and myocyte death. An orally bioavailable GRK2 inhibitor could offer unique therapeutic outcomes that cannot be attained by current heart failure treatments that directly target GPCRs or angiotensin-converting enzyme. Herein, we describe the discovery of a potent, selective, and orally bioavailable GRK2 inhibitor, 8h, through high-throughput screening, hit-to-lead optimization, structure-based design, molecular modelling, synthesis, and biological evaluation.

Repolarization studies using human stem cell-derived cardiomyocytes: Validation studies and best practice recommendations.

Human stem cell-derived cardiomyocytes (hSC-CMs) hold great promise as in vitro models to study the electrophysiological effects of novel drug candidates on human ventricular repolarization. Two recent large validation studies have demonstrated the ability of hSC-CMs to detect drug-induced delayed repolarization and "cellrhythmias" (interrupted repolarization or irregular spontaneous beating of myocytes) linked to Torsade-de-Pointes proarrhythmic risk. These (and other) studies have also revealed variability of electrophysiological responses attributable to differences in experimental approaches and experimenter, protocols, technology platforms used, and pharmacologic sensitivity of different human-derived models.

Pharmacological Profile of the Sodium Current in Human Stem Cell-Derived Cardiomyocytes Compares to Heterologous Nav1.5+β1 Model.

The cardiac Nav1.5 mediated sodium current (I) generates the upstroke of the action potential in atrial and ventricular myocytes. Drugs that modulate this current can therefore be antiarrhythmic or proarrhythmic, which requires preclinical evaluation of their potential drug-induced inhibition or modulation of Nav1.

Assessing Drug-Induced Long QT and Proarrhythmic Risk Using Human Stem-Cell-Derived Cardiomyocytes in a Ca2+ Imaging Assay: Evaluation of 28 CiPA Compounds at Three Test Sites.

The goal of this research consortium including Janssen, MSD, Ncardia, FNCR/LBR, and Health and Environmental Sciences Institute (HESI) was to evaluate the utility of an additional in vitro assay technology to detect potential drug-induced long QT and torsade de pointes (TdP) risk by monitoring cytosolic free Ca2+ transients in human stem-cell-derived cardiomyocytes (hSC-CMs). The potential proarrhythmic risks of the 28 comprehensive in vitro proarrhythmia assay (CiPA) drugs linked to low, intermediate, and high clinical TdP risk were evaluated in a blinded manner using Ca2+-sensitive fluorescent dye assay recorded from a kinetic plate reader system (Hamamatsu FDSS/µCell and FDSS7000) in 2D cultures of 2 commercially available hSC-CM lines (Cor.4U and CDI iCell Cardiomyocytes) at 3 different test sites.

Development of a Human iPSC Cardiomyocyte-Based Scoring System for Cardiac Hazard Identification in Early Drug Safety De-risking.

Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) have emerged as a promising cardiac safety platform, demonstrated by numerous validation studies using drugs with known cardiac adverse effects in humans. However, the challenge remains to implement hiPSC-CMs into cardiac de-risking of new chemical entities (NCEs) during preclinical drug development. Here, we used the calcium transient screening assay in hiPSC-CMs to develop a hazard score system for cardiac electrical liabilities.

Prognostic value of electrocardiographic time intervals and QT rate dependence in hypertrophic cardiomyopathy.

Introduction: Preventing sudden cardiac death (SCD) is one of the main goals in hypertrophic cardiomyopathy (HCM). Many variables have been proposed, however the European and American guidelines do not incorporate any ECG or Holter monitoring derived variables other than the presence of ventricular arrhythmia in their risk stratification models. In the present study we evaluated electrocardiographic parameters in risk stratification of HCM.

Monitoring reperfused myocardial infarction with delayed left ventricular systolic dysfunction in rabbits by longitudinal imaging.

Background: An experimental imaging platform for longitudinal monitoring and evaluation of cardiac morphology-function changes has been long desired. We sought to establish such a platform by using a rabbit model of reperfused myocardial infarction (MI) that develops chronic left ventricle systolic dysfunction (LVSD) within 7 weeks.

Methods: Fifty-five New Zeeland white (NZW) rabbits received sham-operated or 60-min left circumflex coronary artery (LCx) ligation followed by reperfusion.

International Multisite Study of Human-Induced Pluripotent Stem Cell-Derived Cardiomyocytes for Drug Proarrhythmic Potential Assessment.

To assess the utility of human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) as an in vitro proarrhythmia model, we evaluated the concentration dependence and sources of variability of electrophysiologic responses to 28 drugs linked to low, intermediate, and high torsades de pointes (TdP) risk categories using two commercial cell lines and standardized protocols in a blinded multisite study using multielectrode array or voltage-sensing optical approaches. Logistical and ordinal linear regression models were constructed using drug responses as predictors and TdP risk categories as outcomes. Three of seven predictors (drug-induced arrhythmia-like events and prolongation of repolarization at either maximum tested or maximal clinical exposures) categorized drugs with reasonable accuracy (area under the curve values of receiver operator curves ∼0.

Evaluation of cardiac arrhythmic risks using a rabbit model of left ventricular systolic dysfunction.

Patients with heart disease have a higher risk to develop cardiac arrhythmias, either spontaneously or drug-induced. In this study, we have used a rabbit model of myocardial infarction (MI) with severe left ventricular systolic dysfunction (LVSD) to study potential drug-induced cardiac risks with N-(piperidin-2-ylmethyl)-2,5-bis(2,2,2-trifluoroethoxy)benzamide (flecainide). Upon ligation of the left circumflex arteries, male New Zealand White rabbits developed a large MI and moderate or severe LVSD 7 weeks after surgery, in comparison to SHAM-operated animals.

Cross-Site Reliability of Human Induced Pluripotent stem cell-derived Cardiomyocyte Based Safety Assays Using Microelectrode Arrays: Results from a Blinded CiPA Pilot Study.

Recent in vitro cardiac safety studies demonstrate the ability of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) to detect electrophysiologic effects of drugs. However, variability contributed by unique approaches, procedures, cell lines, and reagents across laboratories makes comparisons of results difficult, leading to uncertainty about the role of hiPSC-CMs in defining proarrhythmic risk in drug discovery and regulatory submissions. A blinded pilot study was conducted to evaluate the electrophysiologic effects of 8 well-characterized drugs on 4 cardiomyocyte lines using a standardized protocol across 3 microelectrode array platforms (18 individual studies).

Impact of calcium-sensitive dyes on the beating properties and pharmacological responses of human iPS-derived cardiomyocytes using the calcium transient assay.

Introduction: Calcium-based screening of hiPS-CMs is a useful preclinical safety evaluation platform with the ability to generate robust signals that facilitates high-throughput screening and data analysis. However, due to the potential inherent toxicities, it is important to understand potential effects of different calcium-sensitive dyes on the hiPS-CMs model.

Methods: We compared three calcium-sensitive fluorescence dyes (Cal520, ACTOne and Calcium 5) for their impact on the variability, the beating properties and the pharmacological responses of hiPS-CMs using the Hamamatsu FDSS/μCell imaging platform.

Human Drug Trials Demonstrate Higher Accuracy than Animal Models in Predicting Clinical Pro-Arrhythmic Cardiotoxicity.

Early prediction of cardiotoxicity is critical for drug development. Current animal models raise ethical and translational questions, and have limited accuracy in clinical risk prediction. Human-based computer models constitute a fast, cheap and potentially effective alternative to experimental assays, also facilitating translation to human.

Chronic drug-induced effects on contractile motion properties and cardiac biomarkers in human induced pluripotent stem cell-derived cardiomyocytes.

Background And Purpose: In the pharmaceutical industry risk assessments of chronic cardiac safety liabilities are mostly performed during late stages of preclinical drug development using in vivo animal models. Here, we explored the potential of human induced pluripotent stem cell-derived cardiomyocytes (hiPS-CMs) to detect chronic cardiac risks such as drug-induced cardiomyocyte toxicity.

Experimental Approach: Video microscopy-based motion field imaging was applied to evaluate the chronic effect (over 72 h) of cardiotoxic drugs on the contractile motion of hiPS-CMs.

Assessment of drug-induced proarrhythmia: The importance of study design in the rabbit left ventricular wedge model.

In the present study, we investigated an impact of the stimulation rate on the detection of the proarrhythmic potential of 10 reference compounds with effects on different cardiac ion channels in the isolated arterially-perfused rabbit left ventricular wedge preparation. The compounds were tested in the wedge model using two distinct protocols; including baseline stimulation at 1-Hz followed by a brief period at 0.5-Hz, either without an additional brief period of 2-Hz stimulation (i.

Functional and Transcriptional Characterization of Histone Deacetylase Inhibitor-Mediated Cardiac Adverse Effects in Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes.

Unlabelled: Histone deacetylase (HDAC) inhibitors possess therapeutic potential to reverse aberrant epigenetic changes associated with cancers, neurological diseases, and immune disorders. Unfortunately, clinical studies with some HDAC inhibitors displayed delayed cardiac adverse effects, such as atrial fibrillation and ventricular tachycardia. However, the underlying molecular mechanism(s) of HDAC inhibitor-mediated cardiotoxicity remains poorly understood and is difficult to detect in the early stages of preclinical drug development because of a delayed onset of effects.