CardioMotion: identification of functional and structural cardiotoxic liabilities in small molecules through brightfield kinetic imaging.

Cardiovascular toxicity is an important cause of drug failures in the later stages of drug development, early clinical safety assessment, and even postmarket withdrawals. Early-stage in vitro assessment of potential cardiovascular liabilities in the pharmaceutical industry involves assessment of interactions with cardiac ion channels, as well as induced pluripotent stem cell-derived cardiomyocyte-based functional assays, such as calcium flux and multielectrode-array assays. These methods are appropriate for the identification of acute functional cardiotoxicity but structural cardiotoxicity, which manifests effects after chronic exposure, is often only captured in vivo.

Cardiac sodium channel inhibition by lamotrigine: In vitro characterization and clinical implications.

Lamotrigine, approved for use as an antiseizure medication as well as the treatment of bipolar disorder, inhibits sodium channels in the brain to reduce repetitive neuronal firing and pathological release of glutamate. The shared homology of sodium channels and lack of selectivity associated with channel blocking agents can cause slowing of cardiac conduction and increased proarrhythmic potential. The Vaughan-Williams classification system differentiates sodium channel blockers using biophysical properties of binding.

Time for a Fully Integrated Nonclinical-Clinical Risk Assessment to Streamline QT Prolongation Liability Determinations: A Pharma Industry Perspective.

Defining an appropriate and efficient assessment of drug-induced corrected QT interval (QTc) prolongation (a surrogate marker of torsades de pointes arrhythmia) remains a concern of drug developers and regulators worldwide. In use for over 15 years, the nonclinical International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH) S7B and clinical ICH E14 guidances describe three core assays (S7B: in vitro hERG current & in vivo QTc studies; E14: thorough QT study) that are used to assess the potential of drugs to cause delayed ventricular repolarization. Incorporating these assays during nonclinical or human testing of novel compounds has led to a low prevalence of QTc-prolonging drugs in clinical trials and no new drugs having been removed from the marketplace due to unexpected QTc prolongation.

Blinded, Multicenter Evaluation of Drug-induced Changes in Contractility Using Human-induced Pluripotent Stem Cell-derived Cardiomyocytes.

Animal models are 78% accurate in determining whether drugs will alter contractility of the human heart. To evaluate the suitability of human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) for predictive safety pharmacology, we quantified changes in contractility, voltage, and/or Ca2+ handling in 2D monolayers or 3D engineered heart tissues (EHTs). Protocols were unified via a drug training set, allowing subsequent blinded multicenter evaluation of drugs with known positive, negative, or neutral inotropic effects.

Robotic fluidic coupling and interrogation of multiple vascularized organ chips.

Organ chips can recapitulate organ-level (patho)physiology, yet pharmacokinetic and pharmacodynamic analyses require multi-organ systems linked by vascular perfusion. Here, we describe an 'interrogator' that employs liquid-handling robotics, custom software and an integrated mobile microscope for the automated culture, perfusion, medium addition, fluidic linking, sample collection and in situ microscopy imaging of up to ten organ chips inside a standard tissue-culture incubator. The robotic interrogator maintained the viability and organ-specific functions of eight vascularized, two-channel organ chips (intestine, liver, kidney, heart, lung, skin, blood-brain barrier and brain) for 3 weeks in culture when intermittently fluidically coupled via a common blood substitute through their reservoirs of medium and endothelium-lined vascular channels.

From in vivo to in vitro: The medical device testing paradigm shift.

Amid growing efforts to advance the replacement, reduction, and refinement of the use of animals in research, there is a growing recognition that in vitro testing of medical devices can be more effective, both in terms of cost and time, and also more reliable than in vivo testing. Although the technological landscape has evolved rapidly in support of these concepts, regulatory acceptance of alternative testing methods has not kept pace. Despite the acceptance by regulators of some in vitro tests (cytotoxicity, gene toxicity, and some hemocompatibility assays), many toxicity tests still rely on animals (irritation, sensitization, acute toxicity, reproductive/developmental toxicity), even where other industrial sectors have already abandoned them.

Human Gut-On-A-Chip Supports Polarized Infection of Coxsackie B1 Virus In Vitro.

Analysis of enterovirus infection is difficult in animals because they express different virus receptors than humans, and static cell culture systems do not reproduce the physical complexity of the human intestinal epithelium. Here, using coxsackievirus B1 (CVB1) as a prototype enterovirus strain, we demonstrate that human enterovirus infection, replication and infectious virus production can be analyzed in vitro in a human Gut-on-a-Chip microfluidic device that supports culture of highly differentiated human villus intestinal epithelium under conditions of fluid flow and peristalsis-like motions. When CVB1 was introduced into the epithelium-lined intestinal lumen of the device, virions entered the epithelium, replicated inside the cells producing detectable cytopathic effects (CPEs), and both infectious virions and inflammatory cytokines were released in a polarized manner from the cell apex, as they could be detected in the effluent from the epithelial microchannel.

Matched-Comparative Modeling of Normal and Diseased Human Airway Responses Using a Microengineered Breathing Lung Chip.

Smoking represents a major risk factor for chronic obstructive pulmonary disease (COPD), but it is difficult to characterize smoke-induced injury responses under physiological breathing conditions in humans due to patient-to-patient variability. Here, we show that a small airway-on-a-chip device lined by living human bronchiolar epithelium from normal or COPD patients can be connected to an instrument that "breathes" whole cigarette smoke in and out of the chips to study smoke-induced pathophysiology in vitro. This technology enables true matched comparisons of biological responses by culturing cells from the same individual with or without smoke exposure.

Co-culture of Living Microbiome with Microengineered Human Intestinal Villi in a Gut-on-a-Chip Microfluidic Device.

Here, we describe a protocol to perform long-term co-culture of multi-species human gut microbiome with microengineered intestinal villi in a human gut-on-a-chip microphysiological device. We recapitulate the intestinal lumen-capillary tissue interface in a microfluidic device, where physiological mechanical deformations and fluid shear flow are constantly applied to mimic peristalsis. In the lumen microchannel, human intestinal epithelial Caco-2 cells are cultured to form a 'germ-free' villus epithelium and regenerate small intestinal villi.

Biology-inspired microphysiological system approaches to solve the prediction dilemma of substance testing.

The recent advent of microphysiological systems - microfluidic biomimetic devices that aspire to emulate the biology of human tissues, organs and circulation in vitro - is envisaged to enable a global paradigm shift in drug development. An extraordinary US governmental initiative and various dedicated research programs in Europe and Asia have led recently to the first cutting-edge achievements of human single-organ and multi-organ engineering based on microphysiological systems. The expectation is that test systems established on this basis would model various disease stages, and predict toxicity, immunogenicity, ADME profiles and treatment efficacy prior to clinical testing.

Modeling Hematopoiesis and Responses to Radiation Countermeasures in a Bone Marrow-on-a-Chip.

Studies on hematopoiesis currently rely on animal models because in vitro culture methods do not accurately recapitulate complex bone marrow physiology. We recently described a bone marrow-on-a-chip microfluidic device that enables the culture of living hematopoietic bone marrow and mimics radiation toxicity in vitro. In the present study, we used this microdevice to demonstrate continuous blood cell production in vitro and model bone marrow responses to potential radiation countermeasure drugs.

Small airway-on-a-chip enables analysis of human lung inflammation and drug responses in vitro.

Here we describe the development of a human lung 'small airway-on-a-chip' containing a differentiated, mucociliary bronchiolar epithelium and an underlying microvascular endothelium that experiences fluid flow, which allows for analysis of organ-level lung pathophysiology in vitro. Exposure of the epithelium to interleukin-13 (IL-13) reconstituted the goblet cell hyperplasia, cytokine hypersecretion and decreased ciliary function of asthmatics. Small airway chips lined with epithelial cells from individuals with chronic obstructive pulmonary disease recapitulated features of the disease such as selective cytokine hypersecretion, increased neutrophil recruitment and clinical exacerbation by exposure to viral and bacterial infections.

Organs-on-chips at the frontiers of drug discovery.

Improving the effectiveness of preclinical predictions of human drug responses is critical to reducing costly failures in clinical trials. Recent advances in cell biology, microfabrication and microfluidics have enabled the development of microengineered models of the functional units of human organs - known as organs-on-chips - that could provide the basis for preclinical assays with greater predictive power. Here, we examine the new opportunities for the application of organ-on-chip technologies in a range of areas in preclinical drug discovery, such as target identification and validation, target-based screening, and phenotypic screening.

State-of-the-art of 3D cultures (organs-on-a-chip) in safety testing and pathophysiology.

Integrated approaches using different in vitro methods in combination with bioinformatics can (i) increase the success rate and speed of drug development; (ii) improve the accuracy of toxicological risk assessment; and (iii) increase our understanding of disease. Three-dimensional (3D) cell culture models are important building blocks of this strategy which has emerged during the last years. The majority of these models are organotypic, i.

Microfabrication of human organs-on-chips.

'Organs-on-chips' are microengineered biomimetic systems containing microfluidic channels lined by living human cells, which replicate key functional units of living organs to reconstitute integrated human organ-level pathophysiology in vitro. These microdevices can be used to test efficacy and toxicity of drugs and chemicals, and to create in vitro models of human disease. Thus, they potentially represent low-cost alternatives to conventional animal models for pharmaceutical, chemical and environmental applications.

Clear castable polyurethane elastomer for fabrication of microfluidic devices.

Polydimethylsiloxane (PDMS) has numerous desirable properties for fabricating microfluidic devices, including optical transparency, flexibility, biocompatibility, and fabrication by casting; however, partitioning of small hydrophobic molecules into the bulk of PDMS hinders industrial acceptance of PDMS microfluidic devices for chemical processing and drug development applications. Here we describe an attractive alternative material that is similar to PDMS in terms of optical transparency, flexibility and castability, but that is also resistant to absorption of small hydrophobic molecules.

A mini-microscope for in situ monitoring of cells.

A mini-microscope was developed for in situ monitoring of cells by modifying off-the-shelf components of a commercial webcam. The mini-microscope consists of a CMOS imaging module, a small plastic lens and a white LED illumination source. The CMOS imaging module was connected to a laptop computer through a USB port for image acquisition and analysis.

Discovery of ((1S,3R)-1-isopropyl-3-((3S,4S)-3-methoxy-tetrahydro-2H-pyran-4-ylamino)cyclopentyl)(4-(5-(trifluoromethyl)pyridazin-3-yl)piperazin-1-yl)methanone, PF-4254196, a CCR2 antagonist with an improved cardiovascular profile.

We describe the systematic optimization, focused on the improvement of CV-TI, of a series of CCR2 antagonists. This work resulted in the identification of 10 (((1S,3R)-1-isopropyl-3-((3S,4S)-3-methoxy-tetrahydro-2H-pyran-4-ylamino)cyclopentyl)(4-(5-(trifluoromethyl)pyridazin-3-yl)piperazin-1-yl)methanone) which possessed a low projected human dose 35-45mg BID and a CV-TI=3800-fold.

Palmitate attenuates myocardial contractility through augmentation of repolarizing Kv currents.

There is considerable evidence to support a role for lipotoxicity in the development of diabetic cardiomyopathy, although the molecular links between enhanced saturated fatty acid uptake/metabolism and impaired cardiac function are poorly understood. In the present study, the effects of acute exposure to the saturated fatty acid, palmitate, on myocardial contractility and excitability were examined directly. Exposure of isolated (adult mouse) ventricular myocytes to palmitate, complexed to bovine serum albumin (palmitate:BSA) as in blood, rapidly reduced (by 54+/-4%) mean (+/-SEM) unloaded fractional cell shortening.

Effect of compound plate composition on measurement of hERG current IC(50) using PatchXpress.

Inhibition of the human ether-a-go-go-related gene (hERG) potassium channel by pharmaceutical agents can lead to acquired long QT syndrome and the generation of potentially lethal arrhythmias. Higher throughput automated patch clamp systems, such as PatchXpress, can greatly increase the speed and capacity of evaluation of pharmaceutical compounds for hERG blocking activity. A factor that may affect the IC(50) value of a compound measured in this system is the composition of the multi-well compound plate.

Ca2+-independent alterations in diastolic sarcomere length and relaxation kinetics in a mouse model of lipotoxic diabetic cardiomyopathy.

Previous studies demonstrated increased fatty acid uptake and metabolism in MHC-FATP transgenic mice that overexpress fatty acid transport protein (FATP)1 in the heart under the control of the alpha-myosin heavy chain (alpha-MHC) promoter. Doppler tissue imaging and hemodynamic measurements revealed diastolic dysfunction, in the absence of changes in systolic function. The experiments here directly test the hypothesis that the diastolic dysfunction in MHC-FATP mice reflects impaired ventricular myocyte contractile function.

Evaluation of the rubidium efflux assay for preclinical identification of HERG blockade.

Inhibition of the delayed-rectifier potassium channel current, human ether-a-go-go (hERG), by pharmaceutical agents can lead to acquired long QT syndrome and the generation of potentially lethal arrhythmias and sudden death. There remains an unmet need for higher-throughput assays to screen compounds in preclinical development for the potential to block hERG and cause QT prolongation. We evaluated the rubidium efflux assay for its ability to determine block of the hERG potassium channel.

Embryonic stem cells in predictive cardiotoxicity: laser capture microscopy enables assay development.

Embryonic stem (ES) cells offer unprecedented opportunities for in vitro drug discovery and safety assessment of compounds. Cardiomyocytes derived from ES cells enable development of predictive cardiotoxicity models to increase the safety of novel drugs. Heterogeneity of differentiated ES cells limits the development of reliable in vitro models for compound screening.

Cardiovascular disease and arrhythmias: unique risks in women.

Women have higher risks for symptomatic arrhythmias and sudden death than men. A significantly higher resting heart rate and longer QT interval on electrocardiogram may be factors that predispose women to a serious form of ventricular arrhythmia known as torsades de pointes. Recent studies have demonstrated hormonal effects on the expression of cardiac potassium and calcium ion channels, indicating their possible regulatory role in the modulation of cardiac repolarization and QT interval.

Stereoselective interactions of the enantiomers of chromanol 293B with human voltage-gated potassium channels.

Selective inhibitors of the slow component of the cardiac delayed rectifier K(+) current, I(Ks), are of interest as novel class III antiarrhythmic agents and as tools for studying the physiologic roles of the I(Ks) current. Racemic chromanol 293B is an inhibitor of both native I(Ks) and its putative molecular counterpart, the KvLQT1+minK ion channel complex. We synthesized the (+)-[3S,4R] and (-)-[3R,4S] enantiomers of chromanol 293B using chiral intermediates of known absolute configuration and determined their relative potency to block recombinant human K(+) channels that form the basis for the major repolarizing K(+) currents in human heart, including KvLQT1+minK, human ether-a-go-go-related gene product (hERG), Kv1.