CSAHi study-2: Validation of multi-electrode array systems (MEA60/2100) for prediction of drug-induced proarrhythmia using human iPS cell-derived cardiomyocytes: Assessment of reference compounds and comparison with non-clinical studies and clinical information

Heart rhythm in vitro: measuring stem cell-derived pacemaker cells on microelectrode arrays

Background

Cardiac arrhythmias have markedly increased in recent decades, highlighting the urgent need for appropriate test systems to evaluate the efficacy and safety of new pharmaceuticals and the potential side effects of established drugs.

Methods

The Microelectrode Array (MEA) system may be a suitable option, as it provides both real-time and non-invasive monitoring of cellular networks of spontaneously active cells. However, there is currently no commercially available cell source to apply this technology in the context of the cardiac conduction system (CCS). In response to this problem, our group has previously developed a protocol for the generation of pure functional cardiac pacemaker cells from mouse embryonic stem cells (ESCs). In addition, we compared the hanging drop method, which was previously utilized, with spherical plate-derived embryoid bodies (EBs) and the pacemaker cells that are differentiated from these.

Results

We described the application of these pacemaker cells on the MEA platform, which required a number of crucial optimization steps in terms of coating, dissociation, and cell density. As a result, we were able to generate a monolayer of pure pacemaker cells on an MEA surface that is viable and electromechanically active for weeks. Furthermore, we introduced spherical plates as a convenient and scalable method to be applied for the production of induced sinoatrial bodies.

Conclusion

We provide a tool to transfer modeling and analysis of cardiac rhythm diseases to the cell culture dish. Our system allows answering CCS-related queries within a cellular network, both under baseline conditions and post-drug exposure in a reliable and affordable manner. Ultimately, our approach may provide valuable guidance not only for cardiac pacemaker cells but also for the generation of an MEA test platform using other sensitive non-proliferating cell types.

hiPSC-CM Electrophysiology: Impact of Temporal Changes and Study Parameters on Experimental Reproducibility

Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are frequently used for preclinical cardiotoxicity testing and remain an important tool for confirming model-based predictions of drug effects in accordance with the Comprehensive in Vitro Proarrhythmia Assay (CiPA) initiative. Despite the considerable benefits hiPSC-CMs provide, concerns surrounding experimental reproducibility have emerged. Our study aimed to investigate the effects of temporal changes and experimental parameters on hiPSC-CM electrophysiology. hiPSC-CMs (iCell cardiomyocyte 2 ) were cultured for 14 days and biosignals were acquired using a microelectrode array (MEA) system. Continuous recordings revealed a 22.6% increase in the beating rate and 7.7% decrease in the field potential duration (FPD) during a 20-minute equilibration period. Location specific differences across a multiwell plate were also observed, with hiPSC-CMs in the outer rows beating 8.8 beats per minute (BPM) faster than the inner rows. Cardiac endpoints were also impacted by cell culture duration; from 2-14 days the beating rate decreased (-12.7 BPM), FPD lengthened (+257 ms), and spike amplitude increased (+3.3 mV). Cell culture duration (4-10 days) also impacted hiPSC-CM drug responsiveness (E-4031, nifedipine, isoproterenol). Our study highlights multiple sources of variability that should be considered and addressed when performing hiPSC-CM MEA studies. To improve reproducibility and data interpretation, MEA-based studies should establish a standardized protocol and report key experimental conditions (e.g., culture time, equilibration time, electrical stimulation settings, report raw data values).

New & Noteworthy

We demonstrate that hiPSC-CM electrophysiology measurements are significantly impacted by slight deviations in experimental techniques including electrical stimulation protocols, equilibration time, well-to-well variability, and length of hiPSC-CM culture. Furthermore, our results indicate that hiPSC-CM drug responsiveness changes within the first two weeks following defrost.

Reprogramming iPSCs to study age-related diseases: Models, therapeutics, and clinical trials

The unprecedented rise in life expectancy observed in the last decades is leading to a global increase in the ageing population, and age-associated diseases became an increasing societal, economic, and medical burden. This has boosted major efforts in the scientific and medical research communities to develop and improve therapies to delay ageing and age-associated functional decline and diseases, and to expand health span. The establishment of induced pluripotent stem cells (iPSCs) by reprogramming human somatic cells has revolutionised the modelling and understanding of human diseases. iPSCs have a major advantage relative to other human pluripotent stem cells as their obtention does not require the destruction of embryos like embryonic stem cells do, and do not have a limited proliferation or differentiation potential as adult stem cells. Besides, iPSCs can be generated from somatic cells from healthy individuals or patients, which makes iPSC technology a promising approach to model and decipher the mechanisms underlying the ageing process and age-associated diseases, study drug effects, and develop new therapeutic approaches. This review discusses the advances made in the last decade using iPSC technology to study the most common age-associated diseases, including age-related macular degeneration (AMD), neurodegenerative and cardiovascular diseases, brain stroke, cancer, diabetes, and osteoarthritis.

Human-Induced Pluripotent Stem Cell-Based Differentiation of Cardiomyocyte Subtypes for Drug Discovery and Cell Therapy

Drug attrition rates have increased over the past few years, accompanied with growing costs for the pharmaceutical industry and consumers. Lack of in vitro models connecting the results of toxicity screening assays with clinical outcomes accounts for this high attrition rate. The emergence of cardiomyocytes derived from human pluripotent stem cells provides an amenable source of cells for disease modeling, drug discovery, and cardiotoxicity screening. Functionally similar to to embryonic stem cells, but with fewer ethical concerns, induced pluripotent stem cells (iPSCs) can recapitulate patient-specific genetic backgrounds, which would be a huge revolution for personalized medicine. The generated iPSC-derived cardiomyocytes (iPSC-CMs) represent different subtypes including ventricular-, atrial-, and nodal-like cardiomyocytes. Purifying these subtypes for chamber-specific drug screening presents opportunities and challenges. In this chapter, we discuss the strategies for the purification of iPSC-CMs, the use of iPSC-CMs for drug discovery and cardiotoxicity test, and the current limitations of iPSC-CMs that should be overcome for wider and more precise cardiovascular applications.

cAMP-PKA signaling modulates the automaticity of human iPSC-derived cardiomyocytes

Human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) have been used to screen and characterize drugs and to reveal mechanisms underlying cardiac diseases. However, before hiPSC-CMs can be used as a reliable experimental model, the physiological mechanisms underlying their normal function should be further explored. Accordingly, a major feature of hiPSC-CMs is automaticity, which is regulated by both Ca2+ and membrane clocks. To investigate the mechanisms coupling these clocks, we tested three hypotheses: (1) normal automaticity of spontaneously beating hiPSC-CMs is regulated by local Ca2+ releases (LCRs) and cAMP/PKA-dependent coupling of Ca2+ clock to M clock; (2) the LCR period indicates the level of crosstalk within the coupled-clock system; and (3) perturbing the activity of even one clock can lead to hiPSC-CM-altered automaticity due to diminished crosstalk within the coupled-clock system. By measuring the local and global Ca2+ transients, we found that the LCRs properties are correlated with the spontaneous beat interval. Changes in cAMP-dependent coupling of the Ca2+ and M clocks, caused by a pharmacological intervention that either activates the β-adrenergic or cholinergic receptor or upregulates/downregulates PKA signaling, affected LCR properties, which in turn altered hiPSC-CMs automaticity. Clocks' uncoupling by attenuating the pacemaker current If or the sarcoplasmic reticulum Ca2+ kinetics, decreased hiPSC-CMs beating rate, and prolonged the LCR period. Finally, LCR characteristics of spontaneously beating (at comparable rates) hiPSC-CMs and rabbit SAN are similar. In conclusion, hiPSC-CM automaticity is controlled by the coupled-clock system whose function is mediated by Ca2+-cAMP-PKA signaling.

High-Throughput Drug Screening System Based on Human Induced Pluripotent Stem Cell-Derived Atrial Myocytes ∼ A Novel Platform to Detect Cardiac Toxicity for Atrial Arrhythmias

Evaluation of proarrhythmic properties is critical for drug discovery. In particular, QT prolongation in electrocardiograms has been utilized as a surrogate marker in many evaluation systems to assess the risk of torsade de pointes and lethal ventricular arrhythmia. Recently, new evaluation systems based on human iPS cell-derived cardiomyocytes have been established. On the other hand, in clinical situations, it has been reported that the incidence of atrial arrhythmias such as atrial fibrillation has been increasing every year, with the prediction of a persistent increase in the near future. As to the increased incidence of atrial arrhythmias, in addition to the increased population of geriatric patients, a wide variety of drug treatments may be related, as an experimental method to detect drug-induced atrial arrhythmia has not been established so far. In the present study, we characterized the atrial-like cardiomyocytes derived from human induced pluripotent stem cells and examined their potential for the evaluation of drug-induced atrial arrhythmia. Atrial-like cardiomyocytes were induced by adding retinoic acid (RA) during the process of myocardial differentiation, and their characteristics were compared to those of RA-free cardiomyocytes. Using gene expression and membrane potential analysis, it was confirmed that the cells with or without RA treatment have atrial or ventricular like cardiomyocytes, respectively. Using the ultra-rapid activating delayed rectifier potassium current (I_Kur) channel inhibitor, which is specific to atrial cardiomyocytes, Pulse width duration (PWD) 30cF prolongation was confirmed only in atrial-like cardiomyocytes. In addition, ventricular like cardiomyocytes exhibited an early after depolarization by treatment with rapidly activating delayed rectifier potassium current (I_Kr) channel inhibitor, which induces ventricular arrhythmia in clinical situations. Here, we have established a high-throughput drug evaluation system using human iPS cell-derived atrial-like cardiomyocytes. Based on the obtained data, the system might be a valuable platform to detect potential risks for drug-induced atrial arrhythmias.

Investigation of cardiac glycosides from oleander in a human induced pluripotent stem cells derived cardiomyocyte model

The ingestion of Nerium oleander and Thevetia peruviana are common causes for poisoning in Southeast Asia. All parts of the oleander shrub contain cardiac glycosides of the cardenolide type. These glycosides act via inhibition of a Na⁺/K⁺-ATPase which might cause severe arrhythmia and subsequent death in oleander-poisoned patients. The current study uses human induced pluripotent stem cells derived cardiomyocytes (hiPSC-CM) in a microelectrode array (MEA) system to assess the cardiac effects of neriifolin, oleandrin, digitoxigenin, peruvoside and thevetin A from the oleander plant. Digoxin was used as established reference compound. All tested compounds showed a corrected field potential duration (FPDc) shortening and was the lowest for 600 nM digitoxigenin with -36.9 ± 1.2 %. Next to the dose-dependent pro-arrhythmic potential, a complete beat arrest of the spontaneously beating hiPSC-CM was observed at a concentration of 300 nM for neriifolin, 600 nM for oleandrin and 1000 nM for digitoxigenin and peruvoside. Thevetin A did not cause arrhythmia up to a final concentration of 1000 nM. Thus, it was possible to establish a cardiac effect rank order of the tested substances: neriifolin > oleandrin > digitoxigenin = peruvoside > digoxin > thevetin A.

Improving reliability and reducing costs of cardiotoxicity assessments using laser-induced cell poration on microelectrode arrays

Drug-induced cardiotoxicity is a major barrier to drug development and a main cause of withdrawal of marketed drugs. Drugs can strongly alter the spontaneous functioning of the heart by interacting with the cardiac membrane ion channels. If these effects only surface during in vivo preclinical tests, clinical trials or worse after commercialization, the societal and economic burden will be significant and seriously hinder the efficient drug development process. Hence, cardiac safety pharmacology requires in vitro electrophysiological screening assays of all drug candidates to predict cardiotoxic effects before clinical trials. In the past 10 years, microelectrode array (MEA) technology began to be considered a valuable approach in pharmaceutical applications. However, an effective tool for high-throughput intracellular measurements, compatible with pharmaceutical standards, is not yet available. Here, we propose laser-induced optoacoustic poration combined with CMOS-MEA technology as a reliable and effective platform to detect cardiotoxicity. This approach enables the acquisition of high-quality action potential recordings from large numbers of cardiomyocytes within the same culture well, providing reliable data using single-well MEA devices and single cardiac syncytia per each drug. Thus, this technology could be applied in drug safety screening platforms reducing times and costs of cardiotoxicity assessments, while simultaneously improving the data reliability.

Building Multi-Dimensional Induced Pluripotent Stem Cells-Based Model Platforms to Assess Cardiotoxicity in Cancer Therapies

Cardiovascular disease (CVD) complications have contributed significantly toward poor survival of cancer patients worldwide. These complications that result in myocardial and vascular damage lead to long-term multisystemic disorders. In some patient cohorts, the progression from acute to symptomatic CVD state may be accelerated due to exacerbation of underlying comorbidities such as obesity, diabetes and hypertension. In such situations, cardio-oncologists are often left with a clinical predicament in finding the optimal therapeutic balance to minimize cardiovascular risks and maximize the benefits in treating cancer. Hence, prognostically there is an urgent need for cost-effective, rapid, sensitive and patient-specific screening platform to allow risk-adapted decision making to prevent cancer therapy related cardiotoxicity. In recent years, momentous progress has been made toward the successful derivation of human cardiovascular cells from induced pluripotent stem cells (iPSCs). This technology has not only provided deeper mechanistic insights into basic cardiovascular biology but has also seamlessly integrated within the drug screening and discovery programs for early efficacy and safety evaluation. In this review, we discuss how iPSC-derived cardiovascular cells have been utilized for testing oncotherapeutics to pre-determine patient predisposition to cardiovascular toxicity. Lastly, we highlight the convergence of tissue engineering technologies and precision medicine that can enable patient-specific cardiotoxicity prognosis and treatment on a multi-organ level.

Effects of Cryopreservation on Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes for Assessing Drug Safety Response Profiles

Burgeoning applications of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) in disease modeling, regenerative medicine, and drug screening have broadened the usage of hiPSC-CMs and entailed their long-term storage. Cryopreservation is the most common approach to store hiPSC-CMs. However, the effects of cryopreservation and recovery on hiPSC-CMs remain poorly understood. Here, we characterized the transcriptome, electro-mechanical function, and drug response of fresh hiPSC-CMs without cryopreservation and recovered hiPSC-CMs from cryopreservation. We found that recovered hiPSC-CMs showed upregulation of cell cycle genes, similar or reduced contractility, Ca2+ transients, and field potential duration. When subjected to treatment of drugs that affect electrophysiological properties, recovered hiPSC-CMs showed an altered drug response and enhanced propensity for drug-induced cardiac arrhythmic events. In conclusion, fresh and recovered hiPSC-CMs do not always show comparable molecular and physiological properties. When cryopreserved hiPSC-CMs are used for assessing drug-induced cardiac liabilities, the altered drug sensitivity needs to be considered.

A greedy classifier optimization strategy to assess ion channel blocking activity and pro-arrhythmia in hiPSC-cardiomyocytes

Novel studies conducting cardiac safety assessment using human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are promising but might be limited by their specificity and predictivity. It is often challenging to correctly classify ion channel blockers or to sufficiently predict the risk for Torsade de Pointes (TdP). In this study, we developed a method combining in vitro and in silico experiments to improve machine learning approaches in delivering fast and reliable prediction of drug-induced ion-channel blockade and proarrhythmic behaviour. The algorithm is based on the construction of a dictionary and a greedy optimization, leading to the definition of optimal classifiers. Finally, we present a numerical tool that can accurately predict compound-induced pro-arrhythmic risk and involvement of sodium, calcium and potassium channels, based on hiPSC-CM field potential data.

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. The Ca2+ transient assay, performed at the 3 sites using the 2 different hSC-CMs lines, correctly detected potential drug-induced QT prolongation among the 28 CiPA drugs and detected cellular arrhythmias-like/early afterdepolarization in 7 of 8 high TdP-risk drugs (87.5%), 6 of 11 intermediate TdP-risk drugs (54.5%), and 0 of 9 low/no TdP-risk drugs (0%). The results were comparable among the 3 sites and from 2 hSC-CM cell lines. The Ca2+ transient assay can serve as a user-friendly and higher throughput alternative to complement the microelectrode array and voltage-sensing optical action potential recording assays used in the HESI-CiPA study for in vitro assessment of drug-induced long QT and TdP risk.

Evaluation of in vitro models of stem cell-derived cardiomyocytes to screen for potential cardiotoxicity of chemicals

Cardiotoxicity is an important toxicological endpoint for chemical and drug safety assessment. The present study aims to evaluate two stemcell-based in vitro models for cardiotoxicity screening of chemicals. Eleven model compounds were used to evaluate responses of mouse embryonic stem cell-derived cardiomyocytes (mESC-CMs) using beating arrest as a readout and the analysis of electrophysiological parameters measured with a multi-electrode array (MEA) platform of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). Results revealed that the hiPSC-CM MEA assay responded to all compounds. The mESC-CM beating arrest assay was not responsive to potassium channel blockers and showed a lower sensitivity to sodium channel blockers and Na⁺/K⁺ ATPase inhibitors compared to the hiPSC-CM MEA assay. Calcium channel blockers and a β-adrenergic receptor agonist showed comparable potencies in both models. The in vitro response concentrations from hiPSC-CMs were highly concordant with human effective serum concentrations of potassium and sodium channel blockers. It is concluded that both in vitro models enable the cardiotoxicity screening with different applicability domains. The mESC-CM beating arrest assay may be used as a first step in a tiered approach while the hiPSC-CM MEA assay may be the best starting point for quantitative in vitro to in vivo extrapolations.

Integrating in vitro data and physiologically based kinetic modeling-facilitated reverse dosimetry to predict human cardiotoxicity of methadone

Development of novel testing strategies to detect adverse human health effects is of interest to replace in vivo-based drug and chemical safety testing. The aim of the present study was to investigate whether physiologically based kinetic (PBK) modeling-facilitated conversion of in vitro toxicity data is an adequate approach to predict in vivo cardiotoxicity in humans. To enable evaluation of predictions made, methadone was selected as the model compound, being a compound for which data on both kinetics and cardiotoxicity in humans are available. A PBK model for methadone in humans was developed and evaluated against available kinetic data presenting an adequate match. Use of the developed PBK model to convert concentration–response curves for the effect of methadone on human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM) in the so-called multi electrode array (MEA) assay resulted in predictions for in vivo dose–response curves for methadone-induced cardiotoxicity that matched the available in vivo data. The results also revealed differences in protein plasma binding of methadone to be a potential factor underlying variation between individuals with respect to sensitivity towards the cardiotoxic effects of methadone. The present study provides a proof-of-principle of using PBK modeling-based reverse dosimetry of in vitro data for the prediction of cardiotoxicity in humans, providing a novel testing strategy in cardiac safety studies.

Comprehensive Cardiac Safety Assessment using hiPS-cardiomyocytes (Consortium for Safety Assessment using Human iPS Cells: CSAHi)

Current cardiac safety assessment platforms (in vitro hERG-centric, APD, and/or in vivo animal QT assays) are not fully predictive of drug-induced Torsades de Pointes (TdP) and do not address other mechanism-based arrhythmia, including ventricular tachycardia or ventricular fibrillation, or cardiac safety liabilities such as contractile and structural cardiotoxicity which are another growing safety concerns. We organized the Consortium for Safety Assessment using Human iPS cells (CSAHi; http://csahi.org/en/) in 2013, based on the Japan Pharmaceutical Manufacturers Association (JPMA), to verify the application of human iPS/ES cell-derived cardiomyocytes for drug safety evaluation. The CSAHi HEART team focused on comprehensive screening strategies to predict a diverse range of cardiotoxicities using recently introduced platforms such as the Multi-Electrode Array (MEA), cellular impedance, Motion Field Imaging (MFI), and optical imaging of Ca transient to identify strengths and weaknesses of each platform. Our study showed that hiPS-CMs used in these platforms could detect pharmacological responses that were more relevant to humans compared to existing hERG, APD, or Langendorff (MAPD/contraction) assays. Further, MEA and other methods such as impedance, MFI, and Ca transient assays provided paradigm changes of platforms for predicting drug-induced QT risk and/or arrhythmia or contractile dysfunctions. In contrast, since discordances such as overestimation (false positive) of arrhythmogenicity, oversight, or opposite conclusions in positive inotropic and negative chronotropic activities to some compounds were also confirmed, possibly due to their functional immaturity of hiPS-CMs, hiPS-CMs should be used in these platforms for cardiac safety assessment based upon their advantages and disadvantages.

hiPSCs Derived Cardiac Cells for Drug and Toxicity Screening and Disease Modeling: What Micro- Electrode-Array Analyses Can Tell Us

Human induced pluripotent stem cell (iPSC)-derived cardiomyocytes (CM) have been intensively used in drug development and disease modeling. Since iPSC-cardiomyocyte (CM) was first generated, their characterization has become a major focus of research. Multi-/micro-electrode array (MEA) systems provide a non-invasive user-friendly platform for detailed electrophysiological analysis of iPSC cardiomyocytes including drug testing to identify potential targets and the assessment of proarrhythmic risk. Here, we provide a systematical overview about the physiological and technical background of micro-electrode array measurements of iPSC-CM. We introduce the similarities and differences between action- and field potential and the advantages and drawbacks of MEA technology. In addition, we present current studies focusing on proarrhythmic side effects of novel and established compounds combining MEA systems and iPSC-CM. MEA technology will help to open a new gateway for novel therapies in cardiovascular diseases while reducing animal experiments at the same time.

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. Tolerance interval calculations and evaluation of different classes of cardio-active drugs enabled us to develop a weighted scoring matrix. This approach allowed the translation of various pharmacological effects in hiPSC-CMs into a single hazard label (no, low, high, or very high hazard). Evaluation of 587 internal NCEs and good translation to ex vivo and in vivo models for a subset of these NCEs highlight the value of the cardiac hazard scoring in facilitating the selection of compounds during early drug safety screening.

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Scoring system identifies different degrees of cardiac hazard

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Can be applied within R&D to cardiac safety screening of NCEs

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Controls and reference drugs are essential for development of scoring matrix

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Analysis can be applied to other in vitro drug safety assays

Cardiotoxicity screening of illicit drugs and new psychoactive substances (NPS) in human iPSC-derived cardiomyocytes using microelectrode array (MEA) recordings

The use of recreational drugs, including new psychoactive substances (NPS), is paralleled by emergency department visits of drug users with severe cardiotoxicity. Drug-induced cardiotoxicity can be the (secondary) result of increased norepinephrine blood concentrations, but data on potential drug-induced direct effects on cardiomyocyte function are scarce. The presence of hundreds of NPS therefore calls for efficient screening models to assess direct cardiotoxicity. We investigated effects of four reference compounds (3-30 nM dofetilide, nifedipine and isoproterenol, and 1-10 μM mexiletine) and six recreational drugs (0.01-100 μM cocaine, 0.01-1000 μM amphetamine, MDMA, 4-fluoroamphetamine, α-PVP and MDPV) on cardiomyocyte function (beat rate, spike amplitude and field potential duration (FPD ≈ QT interval in ECGs)), using Pluricyte® human-induced pluripotent stem cell (hiPSC)-derived cardiomyocytes cultured on ready-to-use CardioPlate™ multi-well microelectrode arrays (mwMEAs). Moreover, the effects of exposure to recreational drugs on cell viability were assessed. Effects of reference compounds were in accordance with the literature, indicating the presence of hERG potassium (dofetilide), sodium (mexiletine) and calcium (nifedipine) channels and α-adrenergic receptors (isoproterenol). All recreational drugs decreased the spike amplitude at 10-100 μM. All amphetamine-type stimulants and α-PVP decreased the beat rate at 300 μM, while cocaine and MDPV did so at 10 μM and 30 μM, respectively. All drugs increased the FPD, however at varying concentrations. MDMA, MDPV and amphetamine affected cardiomyocyte function at concentrations relevant for human exposure, while other drugs affected cardiomyocyte function only at higher concentrations (≥ 10 μM). Cell viability was only mildly affected at concentrations well above the lowest concentrations affecting cardiomyocyte function. We demonstrate that MEA recordings of hiPSC-derived cardiomyocytes enable screening for acute, direct effects on cardiomyocyte function. Our data further indicate that tachycardia in patients exposed to recreational drugs is likely due to indirect drug effects, while prolonged repolarization periods (prolonged QT_c interval) could (partly) result from direct drug effects on cardiomyocyte function.

Action potential response of human induced-pluripotent stem cell derived cardiomyocytes to the 28 CiPA compounds: A non-core site data report of the CiPA study

We used the whole-cell current clamp technique to examine the response of our in-house hiPSC-CMs to the 28 CiPA-selected compounds, aiming to compare field potential via MEA from core-sites and action potential via current clamp measurement. Our blinded study showed that all seven high-risk test compounds, including bepridil, caused early afterdepolarizations (EADs) at mid-high and/or high concentration(s). All hERG channel blockers in the mid-risk category prolonged APD30 and APD90 at mid-high, and then led to EADs at their respective high concentrations; while chlorpromazine, clarithromycin and risperidone showed little effects. In addition, ranolazine was the only low-risk test compound to prolong APD30 and APD90 at mid-high, and then produce EADs at high concentration. In conclusion, our results generally agreed with data from all core-sites of the CiPA consortium using the MEA method. Moreover, our assay can successfully detect pro-arrhythmic risk of drug candidates such as bepridil with superior sensitivity.

Induced Pluripotent Stem Cells and Their Use in Human Models of Disease and Development

The discovery of somatic cell nuclear transfer proved that somatic cells can carry the same genetic code as the zygote, and that activating parts of this code are sufficient to reprogram the cell to an early developmental state. The discovery of induced pluripotent stem cells (iPSCs) nearly half a century later provided a molecular mechanism for the reprogramming. The initial creation of iPSCs was accomplished by the ectopic expression of four specific genes (OCT4, KLF4, SOX2, and c-Myc; OSKM). iPSCs have since been acquired from a wide range of cell types and a wide range of species, suggesting a universal molecular mechanism. Furthermore, cells have been reprogrammed to iPSCs using a myriad of methods, although OSKM remains the gold standard. The sources for iPSCs are abundant compared with those for other pluripotent stem cells; thus the use of iPSCs to model the development of tissues, organs, and other systems of the body is increasing. iPSCs also, through the reprogramming of patient samples, are being used to model diseases. Moreover, in the 10 years since the first report, human iPSCs are already the basis for new cell therapies and drug discovery that have reached clinical application. In this review, we examine the generation of iPSCs and their application to disease and development.

Human-Induced Pluripotent Stem Cell Technology and Cardiomyocyte Generation: Progress and Clinical Applications. Cells. 2018;7. [PMID: 29799480 PMCID: PMC6025241 DOI: 10.3390/cells7060048]

Human-induced pluripotent stem cells (hiPSCs) are reprogrammed cells that have hallmarks similar to embryonic stem cells including the capacity of self-renewal and differentiation into cardiac myocytes. The improvements in reprogramming and differentiating methods achieved in the past 10 years widened the use of hiPSCs, especially in cardiac research. hiPSC-derived cardiac myocytes (CMs) recapitulate phenotypic differences caused by genetic variations, making them attractive human disease models and useful tools for drug discovery and toxicology testing. In addition, hiPSCs can be used as sources of cells for cardiac regeneration in animal models. Here, we review the advances in the genetic and epigenetic control of cardiomyogenesis that underlies the significant improvement of the induced reprogramming of somatic cells to CMs; the methods used to improve scalability of throughput assays for functional screening and drug testing in vitro; the phenotypic characteristics of hiPSCs-derived CMs and their ability to rescue injured CMs through paracrine effects; we also cover the novel approaches in tissue engineering for hiPSC-derived cardiac tissue generation, and finally, their immunological features and the potential use in biomedical applications.

Development of In Vitro Drug-Induced Cardiotoxicity Assay by Using Three-Dimensional Cardiac Tissues Derived from Human Induced Pluripotent Stem Cells

An in vitro drug-induced cardiotoxicity assay is a critical step in drug discovery for clinical use. The use of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) is promising for this purpose. However, single hiPSC-CMs are limited in their ability to mimic native cardiac tissue structurally and functionally, and the generation of artificial cardiac tissue using hiPSC-CMs is an ongoing challenging. We therefore developed a new method of constructing three-dimensional (3D) artificial tissues in a short time by coating extracellular matrix (ECM) components on cell surfaces. We hypothesized that 3D cardiac tissues derived from hiPSC-CMs (3D-hiPSC-CT) could be used for an in vitro drug-induced cardiotoxicity assay. 3D-hiPSC-CT were generated by fibronectin and gelatin nanofilm coated single hiPSC-CMs. Histologically, 3D-hiPSC-CT exhibited a sarcomere structure in the myocytes and ECM proteins, such as fibronectin, collagen type I/III, and laminin. The administration of cytotoxic doxorubicin at 5.0 μM induced the release of lactate dehydrogenase, while that at 2.0 μM reduced the cell viability. E-4031, human ether-a-go-go related gene (hERG)-type potassium channel blocker, and isoproterenol induced significant changes both in the Ca transient parameters and contractile parameters in a dose-dependent manner. The 3D-hiPSC-CT exhibited doxorubicin-sensitive cytotoxicity and hERG channel blocker/isoproterenol-sensitive electrical activity in vitro, indicating its usefulness for drug-induced cardiotoxicity assays or drug screening systems for drug discovery.