title: Patient-specific induced pluripotent stem-cell models for long-QT syndrome.
abstract: BACKGROUND
  Long-QT syndromes are heritable diseases associated with prolongation of the QT interval on an electrocardiogram and a high risk of sudden cardiac death due to ventricular tachyarrhythmia. In long-QT syndrome type 1, mutations occur in the KCNQ1 gene, which encodes the repolarizing potassium channel mediating the delayed rectifier I(Ks) current.
  
  
  METHODS
  We screened a family affected by long-QT syndrome type 1 and identified an autosomal dominant missense mutation (R190Q) in the KCNQ1 gene. We obtained dermal fibroblasts from two family members and two healthy controls and infected them with retroviral vectors encoding the human transcription factors OCT3/4, SOX2, KLF4, and c-MYC to generate pluripotent stem cells. With the use of a specific protocol, these cells were then directed to differentiate into cardiac myocytes.
  
  
  RESULTS
  Induced pluripotent stem cells maintained the disease genotype of long-QT syndrome type 1 and generated functional myocytes. Individual cells showed a “ventricular,” “atrial,” or “nodal” phenotype, as evidenced by the expression of cell-type–specific markers and as seen in recordings of the action potentials in single cells. The duration of the action potential was markedly prolonged in “ventricular” and “atrial” cells derived from patients with long-QT syndrome type 1, as compared with cells from control subjects. Further characterization of the role of the R190Q–KCNQ1 mutation in the pathogenesis of long-QT syndrome type 1 revealed a dominant negative trafficking defect associated with a 70 to 80% reduction in I(Ks) current and altered channel activation and deactivation properties. Moreover, we showed that myocytes derived from patients with long-QT syndrome type 1 had an increased susceptibility to catecholamine-induced tachyarrhythmia and that beta-blockade attenuated this phenotype.
  
  
  CONCLUSIONS
  We generated patient-specific pluripotent stem cells from members of a family affected by long-QT syndrome type 1 and induced them to differentiate into functional cardiac myocytes. The patient-derived cells recapitulated the electrophysiological features of the disorder. (Funded by the European Research Council and others.)
authors.affiliation: Cardiology Division, First Department of Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Moretti
authors.forename: Milena
authors.initials: M
authors.lastname: Bellin
authors.forename: Andrea
authors.initials: A
authors.lastname: Welling
authors.forename: Christian Billy
authors.initials: CB
authors.lastname: Jung
authors.forename: Jason T
authors.initials: JT
authors.lastname: Lam
authors.forename: Lorenz
authors.initials: L
authors.lastname: Bott-Flügel
authors.forename: Tatjana
authors.initials: T
authors.lastname: Dorn
authors.forename: Alexander
authors.initials: A
authors.lastname: Goedel
authors.forename: Christian
authors.initials: C
authors.lastname: Höhnke
authors.forename: Franz
authors.initials: F
authors.lastname: Hofmann
authors.forename: Melchior
authors.initials: M
authors.lastname: Seyfarth
authors.forename: Daniel
authors.initials: D
authors.lastname: Sinnecker
authors.forename: Albert
authors.initials: A
authors.lastname: Schömig
authors.forename: Karl-Ludwig
authors.initials: KL
authors.lastname: Laugwitz
mesh_terms: D000200:Action Potentials; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology / Q000627:therapeutic use; D000328:Adult; D000368:Aged; D002316:Cardiotonic Agents / Q000494:pharmacology; D002648:Child; D005260:Female; D005347:Fibroblasts / Q000166:cytology; D015870:Gene Expression; D006801:Humans; D057026:Induced Pluripotent Stem Cells / Q000502:physiology*; D007545:Isoproterenol / Q000494:pharmacology; D051657:KCNQ1 Potassium Channel / Q000235:genetics*; D000090062:Kruppel-Like Factor 4; D008297:Male; D020125:Mutation, Missense; D032383:Myocytes, Cardiac / Q000166:cytology* / Q000187:drug effects / Q000502:physiology; D010375:Pedigree; D010641:Phenotype; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D029597:Romano-Ward Syndrome / Q000188:drug therapy / Q000235:genetics / Q000503:physiopathology*
chemical_list: D000319:Adrenergic beta-Antagonists; D002316:Cardiotonic Agents; D051657:KCNQ1 Potassium Channel; C496909:KCNQ1 protein, human; C000715467:KLF4 protein, human; D000090062:Kruppel-Like Factor 4; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D007545:Isoproterenol