title: Human stem cell-derived cardiomyocytes detect drug-mediated changes in action potentials and ion currents.
abstract: BACKGROUND
  It has been proposed that proarrhythmia assessment for safety pharmacology testing includes the use of human pluripotent stem cell-derived cardiomyocytes (hiPSC-CM) to detect drug-induced changes in cardiac electrophysiology. This study measured the actions of diverse agents on action potentials (AP) and ion currents recorded from hiPSC-CM.
  
  
  METHODS
  During AP experiments, the hiPSC-CM were paced at 1Hz during a baseline period, and when increasing concentrations of test compound were administered at 4-minute intervals. AP parameters, including duration (APD60 and APD90), resting membrane potential, rate of rise, and amplitude, were measured throughout the entire experiment. Voltage clamp experiments with E-4031 and nifedipine were similarly conducted.
  
  
  RESULTS
  E-4031 produced a dose-dependent prolongation of cardiac action potential and blocked the hERG/IKr current with an IC50 of 17nM. At 3nM, dofetilide significantly increased APD90. Astemizole significantly increased APD60 and APD90 at 30nM. Terfenadine significantly increased APD90 at concentrations greater than 10nM. Fexofenadine, a metabolite of terfenadine, did not produce any electrophysiologic changes in cardiac action potentials. Flecainide produced a dose-dependent prolongation of the cardiac action potential at 1 and 3μM. Acute exposure to nifedipine significantly decreased APD60 and APD90 and produced a dose-dependent block of calcium current with an IC50 of 0.039μM. Verapamil first shortened APD60 and APD90 in a dose-dependent manner, until a compensating increase in APD90, presumably via hERG blockade, was observed at 1 and 3μM. Following a chronic exposure (20-24h) to clinically relevant levels of pentamidine, a significant increase in action potential duration was accompanied by early afterdepolarizations (EADs).
  
  
  CONCLUSIONS
  These experiments show the ability of AP measured from hiPSC-CM to record the interactions of various ion channels via AP recording and avoid the limitations of using several single ion channel assays in a noncardiac tissue.
authors.affiliation: Ionic Transport Assays, Inc., 1100 Corporate Square Drive, St Louis, MO 63132, USA. Electronic address: ken@ionictransport.com.
authors.forename: John K
authors.initials: JK
authors.lastname: Gibson
authors.affiliation: Ionic Transport Assays, Inc., 1100 Corporate Square Drive, St Louis, MO 63132, USA. Electronic address: yimeiyue@gmail.com.
authors.forename: Yimei
authors.initials: Y
authors.lastname: Yue
authors.affiliation: Ionic Transport Assays, Inc., 1100 Corporate Square Drive, St Louis, MO 63132, USA. Electronic address: jared@ionictransport.com.
authors.forename: Jared
authors.initials: J
authors.lastname: Bronson
authors.affiliation: Ionic Transport Assays, Inc., 1100 Corporate Square Drive, St Louis, MO 63132, USA. Electronic address: cassie@ionictransport.com.
authors.forename: Cassie
authors.initials: C
authors.lastname: Palmer
authors.affiliation: Ionic Transport Assays, Inc., 1100 Corporate Square Drive, St Louis, MO 63132, USA. Electronic address: rnumann@gmail.com.
authors.forename: Randy
authors.initials: R
authors.lastname: Numann
mesh_terms: D000200:Action Potentials / Q000187:drug effects*; D000328:Adult; D016589:Astemizole / Q000494:pharmacology; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004553:Electric Conductivity; D005424:Flecainide / Q000494:pharmacology; D006801:Humans; D057026:Induced Pluripotent Stem Cells / Q000166:cytology*; D007473:Ion Channels / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D009543:Nifedipine / Q000494:pharmacology; D010419:Pentamidine / Q000494:pharmacology; D010627:Phenethylamines / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D013449:Sulfonamides / Q000494:pharmacology; D016593:Terfenadine / Q000031:analogs & derivatives / Q000494:pharmacology; D014700:Verapamil / Q000494:pharmacology
chemical_list: D007473:Ion Channels; D010627:Phenethylamines; D010880:Piperidines; D011725:Pyridines; D013449:Sulfonamides; C063968:E 4031; D010419:Pentamidine; D016593:Terfenadine; D016589:Astemizole; D014700:Verapamil; C093230:fexofenadine; D009543:Nifedipine; D005424:Flecainide; C063533:dofetilide
keywords: APD60; APD90; Action potentials; Astemizole (PubChem CID: 2247); Dofetilide (PubChem CID: 71329); E-4031 (PubChem CID: 5312116); Fexofenadine (PubChem CID: 63002); Flecainide (PubChem CID: 41022); Human induced stem cell-derived cardiomyocytes; Nifedipine (PubChem CID: 4485); Patch-clamp method; Pentamidine (PubChem CID: 8813); Rate of rise; Resting membrane potential; Terfenadine (PubChem CID: 5405); Ventricular-like myocytes; Verapamil-HCl (PubChem CID: 2520)