title: Safety pharmacology studies using EFP and impedance.
abstract: BACKGROUND
  While extracellular field potential (EFP) recordings using multi-electrode arrays (MEAs) are a well-established technique for monitoring changes in cardiac and neuronal function, impedance is a relatively unexploited technology. The combination of EFP, impedance and human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) has important implications for safety pharmacology as functional information about contraction and field potentials can be gleaned from human cardiomyocytes in a beating monolayer. The main objectives of this study were to demonstrate, using a range of different compounds, that drug effects on contraction and electrophysiology can be detected using a beating monolayer of hiPSC-CMs on the CardioExcyte 96.
  
  
  METHODS
  hiPSC-CMs were grown as a monolayer on NSP-96 plates for the CardioExcyte 96 (Nanion Technologies) and recordings were made in combined EFP and impedance mode at physiological temperature. The effect of the hERG blockers, E4031 and dofetilide, hERG trafficking inhibitor, pentamidine, β-adrenergic receptor agonist, isoproterenol, and calcium channel blocker, nifedipine, was tested on the EFP and impedance signals.
  
  
  RESULTS
  Combined impedance and EFP measurements were made from hiPSC-CMs using the CardioExcyte 96 (Nanion Technologies). E4031 and dofetilide, known to cause arrhythmia and Torsades de Pointes (TdP) in humans, decreased beat rate in impedance and EFP modes. Early afterdepolarization (EAD)-like events, an in vitro marker of TdP, could also be detected using this system. Isoproterenol and nifedipine caused an increase in beat rate. A long-term study (over 30h) of pentamidine, a hERG trafficking inhibitor, showed a concentration and time-dependent effect of pentamidine.
  
  
  CONCLUSIONS
  In the light of the new Comprehensive in Vitro Proarrhythmia Assay (CiPA) initiative to improve guidelines and standardize assays and protocols, the use of EFP and impedance measurements from hiPSCs may become critical in determining the proarrhythmic risk of potential drug candidates. The combination of EFP offering information about cardiac electrophysiology, and impedance, providing information about contractility from the same area of a synchronously beating monolayer of human cardiomyocytes in a 96-well plate format has important implications for future cardiac safety testing.
authors.affiliation: Nanion Technologies GmbH, Gabrielenstr. 9, 80636 Munich, Germany. Electronic address: ali@nanion.de.
authors.forename: Alison
authors.initials: A
authors.lastname: Obergrussberger
authors.affiliation: Nanion Technologies GmbH, Gabrielenstr. 9, 80636 Munich, Germany.
authors.forename: Krisztina
authors.initials: K
authors.lastname: Juhasz
authors.affiliation: Nanion Technologies GmbH, Gabrielenstr. 9, 80636 Munich, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Thomas
authors.affiliation: Nanion Technologies GmbH, Gabrielenstr. 9, 80636 Munich, Germany.
authors.forename: Sonja
authors.initials: S
authors.lastname: Stölzle-Feix
authors.affiliation: Nanion Technologies GmbH, Gabrielenstr. 9, 80636 Munich, Germany.
authors.forename: Nadine
authors.initials: N
authors.lastname: Becker
authors.affiliation: Nanion Technologies GmbH, Gabrielenstr. 9, 80636 Munich, Germany.
authors.forename: Leo
authors.initials: L
authors.lastname: Dörr
authors.affiliation: Nanion Technologies GmbH, Gabrielenstr. 9, 80636 Munich, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Beckler
authors.affiliation: Nanion Technologies GmbH, Gabrielenstr. 9, 80636 Munich, Germany.
authors.forename: Corina
authors.initials: C
authors.lastname: Bot
authors.affiliation: Nanion Technologies GmbH, Gabrielenstr. 9, 80636 Munich, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: George
authors.affiliation: Nanion Technologies GmbH, Gabrielenstr. 9, 80636 Munich, Germany.
authors.forename: Niels
authors.initials: N
authors.lastname: Fertig
mesh_terms: D000200:Action Potentials / Q000187:drug effects*; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D001145:Arrhythmias, Cardiac / Q000139:chemically induced / Q000503:physiopathology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002307:Cardiography, Impedance / Q000187:drug effects*; D018929:Cell Culture Techniques; D051638:Ether-A-Go-Go Potassium Channels / Q000187:drug effects; D005110:Extracellular Space / Q000187:drug effects*; D006801:Humans; D057026:Induced Pluripotent Stem Cells / Q000187:drug effects; D032383:Myocytes, Cardiac / Q000187:drug effects; D026902:Potassium Channel Blockers / Q000494:pharmacology; D016171:Torsades de Pointes / Q000139:chemically induced / Q000503:physiopathology
chemical_list: D000319:Adrenergic beta-Antagonists; D002121:Calcium Channel Blockers; D051638:Ether-A-Go-Go Potassium Channels; C496884:KCNH1 protein, human; D026902:Potassium Channel Blockers
keywords: CardioExcyte 96; Dofetilide; E4031; EAD-like; Extracellular field potential; Impedance; Isoproterenol; Nifedipine; Pentamidine; Safety pharmacology