Mechano-Pharmacological Characterization of Cardiomyocytes Derived from Human Induced Pluripotent Stem Cells.

BACKGROUND/AIMS: Common systems for the quantification of cellular contraction rely on animal-based models, complex experimental setups or indirect approaches. The herein presented CellDrum technology for testing mechanical tension of cellular monolayers and thin tissue constructs has the potential to scale-up mechanical testing towards medium-throughput analyses. Using hiPS-Cardiac Myocytes (hiPS-CMs) it represents a new perspective of drug testing and brings us closer to personalized drug medication. METHODS: In the present study, monolayers of self-beating hiPS-CMs were grown on ultra-thin circular silicone membranes and deflect under the weight of the culture medium. Rhythmic contractions of the hiPS-CMs induced variations of the membrane deflection. The recorded contraction-relaxation-cycles were analyzed with respect to their amplitudes, durations, time integrals and frequencies. Besides unstimulated force and tensile stress, we investigated the effects of agonists and antagonists acting on Ca2+ channels (S-Bay K8644/verapamil) and Na+ channels (veratridine/lidocaine). RESULTS: The measured data and simulations for pharmacologically unstimulated contraction resembled findings in native human heart tissue, while the pharmacological dose-response curves were highly accurate and consistent with reference data. CONCLUSION: We conclude that the combination of the CellDrum with hiPS-CMs offers a fast, facile and precise system for pharmacological, toxicological studies and offers new preclinical basic research potential.

Development of a Bioreactor to Culture Tissue Engineered Ureters Based on the Application of Tubular OPTIMAIX 3D Scaffolds.

Regenerative medicine, tissue engineering and biomedical research give hope to many patients who need bio-implants. Tissue engineering applications have already been developed based on bioreactors. Physiological ureter implants, however, do not still function sufficiently, as they represent tubular hollow structures with very specific cellular structures and alignments consisting of several cell types. The aim of this study was to a develop a new bioreactor system based on seamless, collagenous, tubular OPTIMAIX 3D prototype sponge as scaffold material for ex-vivo culturing of a tissue engineered ureter replacement for future urological applications. Particular emphasis was given to a great extent to mimic the physiological environment similar to the in vivo situation of a ureter. NIH-3T3 fibroblasts, C2C12, Urotsa and primary genitourinary tract cells were applied as co-cultures on the scaffold and the penetration of cells into the collagenous material was followed. By the end of this study, the bioreactor was functioning, physiological parameter as temperature and pH and the newly developed BIOREACTOR system is applicable to tubular scaffold materials with different lengths and diameters. The automatized incubation system worked reliably. The tubular OPTIMAIX 3D sponge was a suitable scaffold material for tissue engineering purposes and co-cultivation procedures.

Chamber-specific contractile responses of atrial and ventricular hiPSC-cardiomyocytes to GPCR and ion channel targeting compounds: A microphysiological system for cardiac drug development.

Human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes (CMs) have found utility for conducting in vitro drug screening and disease modelling to gain crucial insights into pharmacology or disease phenotype. However, diseases such as atrial fibrillation, affecting >33 M people worldwide, demonstrate the need for cardiac subtype-specific cells. Here, we sought to investigate the base characteristics and pharmacological differences between commercially available chamber-specific atrial or ventricular hiPSC-CMs seeded onto ultra-thin, flexible PDMS membranes to simultaneously measure contractility in a 96 multi-well format. We investigated the effects of GPCR agonists (acetylcholine and carbachol), a Ca2+ channel agonist (S-Bay K8644), an HCN channel antagonist (ivabradine) and K+ channel antagonists (4-AP and vernakalant). We observed differential effects between atrial and ventricular hiPSC-CMs on contractile properties including beat rate, beat duration, contractile force and evidence of arrhythmias at a range of concentrations. As an excerpt of the compound analysis, S-Bay K8644 treatment showed an induced concentration-dependent transient increase in beat duration of atrial hiPSC-CMs, whereas ventricular cells showed a physiological increase in beat rate over time. Carbachol treatment produced marked effects on atrial cells, such as increased beat duration alongside a decrease in beat rate over time, but only minimal effects on ventricular cardiomyocytes. In the context of this chamber-specific pharmacology, we not only add to contractile characterization of hiPSC-CMs but propose a multi-well platform for medium-throughput early compound screening. Overall, these insights illustrate the key pharmacological differences between chamber-specific cardiomyocytes and their application on a multi-well contractility platform to gain insights for in vitro cardiac liability studies and disease modelling.

Hybrid Cell Analysis System to Assess Structural and Contractile Changes of Human iPSC-Derived Cardiomyocytes for Preclinical Cardiac Risk Evaluation.

Cardiac contractility assessment is of immense importance for the development of new therapeutics and their safe transition into clinical stages. While human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) hold promise to serve as a human-relevant model in preclinical phases of drug discovery and safety pharmacology, their maturity is still controversial in the scientific community and under constant development. We present a hybrid contractility and impedance/extracellular field potential (EFP) technology, adding significant pro-maturation features to an industry-standard 96-well platform. The impedance/EFP system monitors cellular functionality in real-time. Besides the beat rate of contractile cells, the electrical impedance spectroscopy readouts detect compound-induced morphological changes like cell density and integrity of the cellular monolayer. In the other component of the hybrid cell analysis system, the cells are cultured on bio-compliant membranes that mimic the mechanical environment of real heart tissue. This physiological environment supports the maturation of hiPSC-CMs in vitro, leading to more adult-like contractile responses including positive inotropic effects after treatment with isoproterenol, S-Bay K8644, or omecamtiv mecarbil. Parameters such as the amplitude of contraction force (mN/mm2) and beat duration also reveal downstream effects of compounds with influence on electrophysiological properties and calcium handling. The hybrid system provides the ideal tool for holistic cell analysis, allowing preclinical cardiac risk assessment beyond the current perspectives of human-relevant cell-based assays.

Integration of mechanical conditioning into a high throughput contractility assay for cardiac safety assessment.

INDUCTION: Despite increasing acceptance of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) in safety pharmacology, controversy remains about the physiological relevance of existing in vitro models for their mechanical testing. We hypothesize that existing signs of immaturity of the cell models result from an improper mechanical environment. With the presented study, we aimed at validating the newly developed FLEXcyte96 technology with respect to physiological responses of hiPSC-CMs to pharmacological compounds with known inotropic and/or cardiotoxic effects. METHODS: hiPSC-CMs were cultured in a 96-well format on hyperelastic silicone membranes imitating their native mechanical environment. Cardiomyocyte contractility was measured contact-free by application of capacitive displacement sensing of the cell-membrane biohybrids. Acute effects of positive inotropic compounds with distinct mechanisms of action were examined. Additionally, cardiotoxic effects of tyrosine kinase inhibitors and anthracyclines were repetitively examined during repeated exposure to drug concentrations for up to 5 days. RESULTS: hiPSC-CMs grown on biomimetic membranes displayed increased contractility responses to isoproterenol, S-Bay K8644 and omecamtiv mecarbil without the need for additional stimulation. Tyrosine kinase inhibitor erlotinib, vandetanib, nilotinib, gefitinib, A-674563 as well as anthracycline idarubicin showed the expected cardiotoxic effects, including negative inotropy and induction of proarrhythmic events. DISCUSSION: We conclude that the FLEXcyte 96 system is a reliable high throughput tool for invitro cardiac contractility research, providing the user with data obtained under physiological conditions which resemble the native environment of human heart tissue. We showed that the results obtained for both acute and sub-chronic compound administration are consistent with the respective physiological responses in humans.

Synchronized electromechanical integration recording of cardiomyocytes.

Cardiac issues are always one of major health problems that attract wide attention by the public. It is urgent to explore a preclinical strategy to efficiently prevent the life-threatening arrhythmias by precisely assessing the cardiac excitation-contraction behavior. Conventional label-free asynchronous strategies are difficult to synchronously record and precisely match the excitation and contraction signals in vitro, while label-based strategies generally present pharmacological adverse effects and phototoxicity that significantly interfere the natural excitation and contraction signals. Both types of strategies preclude to exactly understand how cardiac excitation-contraction coupling changes in quantitative and coherent detail when dysfunctions occur. Here, we show a label-free synchronized electromechanical integration detection strategy that can synchronously monitor electrical and mechanical signals of cardiomyocytes over a long period of time by an integrated microelectrode-interdigitated electrode (ME-IDE). ME-IDE can detect subtle changes in electromechanical integration signals induced by drugs that target excitation-contraction coupling. Moreover, electromechanical integration delay is explored to specifically recognize the sodium channel inhibition. Furthermore, biomimetic electronic pacemaker function provides an alternative way to efficiently assess the drug-induced arrhythmia using refractory period of cardiomyocytes.

Mechanical induction of bi-directional orientation of primary porcine bladder smooth muscle cells in tubular fibrin-poly(vinylidene fluoride) scaffolds for ureteral and urethral repair using cyclic and focal balloon catheter stimulation.

To restore damaged organ function or to investigate organ mechanisms, it is necessary to prepare replicates that follow the biological role model as faithfully as possible. The interdisciplinary field of tissue engineering has great potential in regenerative medicine and might overcome negative side effects in the replacement of damaged organs. In particular, tubular organ structures of the genitourinary tract, such as the ureter and urethra, are challenging because of their complexity and special milieu that gives rise to incrustation, inflammation and stricture formation. Tubular biohybrids were prepared from primary porcine smooth muscle cells embedded in a fibrin gel with a stabilising poly(vinylidene fluoride) mesh. A mechanotransduction was performed automatically with a balloon kyphoplasty catheter. Diffusion of urea and creatinine, as well as the bursting pressure, were measured. Light and electron microscopy were used to visualise cellular distribution and orientation. Histological evaluation revealed a uniform cellular distribution in the fibrin gel. Mechanical stimulation with a stretch of 20% leads to a circumferential orientation of smooth muscle cells inside the matrix and a longitudinal alignment on the outer surface of the tubular structure. Urea and creatinine permeability and bursting pressure showed a non-statistically significant trend towards stimulated tissue constructs. In this proof of concept study, an innovative technique of intraluminal pressure for mechanical stimulation of tubular biohybrids prepared from autologous cells and a composite material induce bi-directional orientation of smooth muscle cells by locally and cyclically applied mechanical tension. Such geometrically driven patterns of cell growth within a scaffold may represent a key stage in the future tissue engineering of implantable ureter replacements that will allow the active transportation of urine from the renal pelvis into the bladder.

Sample-specific adaption of an improved electro-mechanical model of in vitro cardiac tissue.

We present an electromechanically coupled computational model for the investigation of a thin cardiac tissue construct consisting of human-induced pluripotent stem cell-derived atrial, ventricular and sinoatrial cardiomyocytes. The mechanical and electrophysiological parts of the finite element model, as well as their coupling are explained in detail. The model is implemented in the open source finite element code Code_Aster and is employed for the simulation of a thin circular membrane deflected by a monolayer of autonomously beating, circular, thin cardiac tissue. Two cardio-active drugs, S-Bay K8644 and veratridine, are applied in experiments and simulations and are investigated with respect to their chronotropic effects on the tissue. These results demonstrate the potential of coupled micro- and macroscopic electromechanical models of cardiac tissue to be adapted to experimental results at the cellular level. Further model improvements are discussed taking into account experimentally measurable quantities that can easily be extracted from the obtained experimental results. The goal is to estimate the potential to adapt the presented model to sample specific cell cultures.

rhAPC reduces the endothelial cell permeability via a decrease of contractile tensions induced by endothelial cells.

All cells generate contractile tension. This strain is crucial for mechanically controlling the cell shape, function and survival. In this study, the CellDrum technology quantifying cell's (the cellular) mechanical tension on a pico-scale was used to investigate the effect of lipopolysaccharide (LPS) on human aortic endothelial cell (HAoEC) tension. The LPS effect during gram-negative sepsis on endothelial cells is cell contraction causing endothelium permeability increase. The aim was to finding out whether recombinant activated protein C (rhAPC) would reverse the endothelial cell response in an in-vitro sepsis model. In this study, the established in-vitro sepsis model was confirmed by interleukin 6 (IL-6) levels at the proteomic and genomic levels by ELISA, real time-PCR and reactive oxygen species (ROS) activation by florescence staining. The thrombin cellular contraction effect on endothelial cells was used as a positive control when the CellDrum technology was applied. Additionally, the Ras homolog gene family, member A (RhoA) mRNA expression level was checked by real time-PCR to support contractile tension results. According to contractile tension results, the mechanical predominance of actin stress fibers was a reason of the increased endothelial contractile tension leading to enhanced endothelium contractility and thus permeability enhancement. The originality of this data supports firstly the basic measurement principles of the CellDrum technology and secondly that rhAPC has a beneficial effect on sepsis influenced cellular tension. The technology presented here is promising for future high-throughput cellular tension analysis that will help identify pathological contractile tension responses of cells and prove further cell in-vitro models.