title: Pharmacological response of human cardiomyocytes derived from virus-free induced pluripotent stem cells.
abstract: OBJECTIVE
  Generation of human induced pluripotent stem cell (hiPSC) lines by reprogramming of fibroblast cells with virus-free methods offers unique opportunities for translational cardiovascular medicine. The aim of the study was to reprogramme fibroblast cells to hiPSCs and to study cardiomyogenic properties and ion channel characteristics of the virus-free hiPSC-derived cardiomyocytes.
  
  
  RESULTS
  The hiPSCs generated by episomal vectors generated teratomas in severe combined immunodeficient mice, readily formed embryoid bodies, and differentiated into cardiomyocytes with comparable efficiency to human embryonic stem cells. Temporal gene expression of these hiPSCs indicated that differentiation of cardiomyocytes was initiated by increasing expression of cardio/mesodermal markers followed by cardiac-specific transcription factors, structural, and ion channel genes. Furthermore, the cardiomyocytes showed characteristic cross-striations of sarcomeric proteins and expressed calcium-handling and ion channel proteins, confirming their cardiac ontogeny. Microelectrode array recordings established the electrotonic development of a functional syncytium that responded predictably to pharmacologically active drugs. The cardiomyocytes showed a chronotropic dose-response (0.1-10 µM) to isoprenaline and Bay K 8644. Furthermore, carbamycholine (5 µM) suppressed the response to isoprenaline, while verapamil (2.5 µM) blocked Bay K 8644-induced inotropic activity. Moreover, verapamil (1 µM) reduced the corrected field potential duration by 45%, tetrodotoxin (10 µM) shortened the minimal field potential by 40%, and E-4031 (50 nM) prolonged field repolarization.
  
  
  CONCLUSIONS
  Virus-free hiPSCs differentiate efficiently into cardiomyocytes with cardiac-specific molecular, structural, and functional properties that recapitulate the developmental ontogeny of cardiogenesis. These results, coupled with the potential to generate patient-specific hiPSC lines, hold great promise for the development of an in vitro platform for drug pharmacogenomics, disease modelling, and regenerative medicine.
authors.affiliation: Research and Development Unit, National Heart Centre Singapore, 17, Third Hospital Avenue, Mistri Wing, Singapore 168752.
authors.forename: Ashish
authors.initials: A
authors.lastname: Mehta
authors.forename: Ying Ying
authors.initials: YY
authors.lastname: Chung
authors.forename: Alvin
authors.initials: A
authors.lastname: Ng
authors.forename: Fahamy
authors.initials: F
authors.lastname: Iskandar
authors.forename: Shirhan
authors.initials: S
authors.lastname: Atan
authors.forename: Heming
authors.initials: H
authors.lastname: Wei
authors.forename: Greg
authors.initials: G
authors.lastname: Dusting
authors.forename: William
authors.initials: W
authors.lastname: Sun
authors.forename: Philip
authors.initials: P
authors.lastname: Wong
authors.forename: Winston
authors.initials: W
authors.lastname: Shim
mesh_terms: D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000818:Animals; D002454:Cell Differentiation; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004353:Drug Evaluation, Preclinical; D006801:Humans; D057026:Induced Pluripotent Stem Cells / Q000166:cytology*; D051379:Mice; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D014700:Verapamil / Q000494:pharmacology
chemical_list: D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D014700:Verapamil