title: Modeling type 3 long QT syndrome with cardiomyocytes derived from patient-specific induced pluripotent stem cells.
abstract: BACKGROUND
  Type 3 long QT syndrome (LQT3) is the third most common form of LQT syndrome and is characterized by QT-interval prolongation resulting from a gain-of-function mutation in SCN5A. We aimed to establish a patient-specific human induced pluripotent stem cell (hiPSC) model of LQT3, which could be used for future drug testing and development of novel treatments for this inherited disorder.
  
  
  RESULTS
  Dermal fibroblasts obtained from a patient with LQT3 harboring a SCN5A mutation (c.5287G>A; p.V1763M) were reprogrammed to hiPSCs via repeated transfection of mRNA encoding OCT-4, SOX-2, KLF-4, C-MYC and LIN-28. hiPSC-derived cardiomyocytes (hiPSC-CMs) were obtained via cardiac differentiation. hiPSC-CMs derived from the patient's healthy sister were used as a control. Compared to the control, patient hiPSC-CMs exhibited dominant mutant SCN5A allele gene expression, significantly prolonged action potential duration or APD (paced CMs of control vs. patient: 226.50 ± 17.89 ms vs. 536.59 ± 37.1 ms; mean ± SEM, p < 0.005), an increased tetrodotoxin (TTX)-sensitive late or persistent Na(+) current (control vs. patient: 0.65 ± 0.11 vs. 3.16 ± 0.27 pA/pF; n = 9, p < 0.01), a positive shift of steady state inactivation and a faster recovery from inactivation. Mexiletine, a NaV1.5 blocker, reversed the elevated late Na(+) current and prolonged APD in LQT3 hiPSC-CMs.
  
  
  CONCLUSIONS
  We demonstrate that hiPSC-CMs derived from a LQT3 patient recapitulate the biophysical abnormalities that define LQT3. The clinical significance of such an in vitro model is in the development of novel therapeutic strategies and a more personalized approach in testing drugs on patients with LQT3.
authors.affiliation: Research and Development Unit (RDU), National Heart Centre Singapore, Singapore.
authors.forename: Dongrui
authors.initials: D
authors.lastname: Ma
authors.forename: Heming
authors.initials: H
authors.lastname: Wei
authors.forename: Yongxing
authors.initials: Y
authors.lastname: Zhao
authors.forename: Jun
authors.initials: J
authors.lastname: Lu
authors.forename: Guang
authors.initials: G
authors.lastname: Li
authors.forename: Norliza Binte Esmail
authors.initials: NB
authors.lastname: Sahib
authors.forename: Teng Hong
authors.initials: TH
authors.lastname: Tan
authors.forename: Keng Yean
authors.initials: KY
authors.lastname: Wong
authors.forename: Winston
authors.initials: W
authors.lastname: Shim
authors.forename: Philip
authors.initials: P
authors.lastname: Wong
authors.forename: Stuart A
authors.initials: SA
authors.lastname: Cook
authors.forename: Reginald
authors.initials: R
authors.lastname: Liew
mesh_terms: D000200:Action Potentials / Q000502:physiology; D002648:Child; D002675:Child, Preschool; D002893:Chromosomes, Human, Pair 3; D020405:Dermis / Q000166:cytology; D004562:Electrocardiography; D005260:Female; D005347:Fibroblasts / Q000166:cytology / Q000502:physiology; D005838:Genotype; D006323:Heart Arrest / Q000235:genetics / Q000503:physiopathology; D006801:Humans; D008133:Long QT Syndrome / Q000235:genetics / Q000503:physiopathology*; D008564:Membrane Potentials / Q000502:physiology; D008801:Mexiletine / Q000494:pharmacology; D032383:Myocytes, Cardiac / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D062554:NAV1.5 Voltage-Gated Sodium Channel / Q000235:genetics; D018408:Patch-Clamp Techniques; D039904:Pluripotent Stem Cells / Q000166:cytology*; D061567:Voltage-Gated Sodium Channel Blockers / Q000494:pharmacology
chemical_list: D062554:NAV1.5 Voltage-Gated Sodium Channel; C568320:SCN5A protein, human; D061567:Voltage-Gated Sodium Channel Blockers; D008801:Mexiletine
keywords: Cardiomyocytes; Induced pluripotent stem cells; Long QT syndrome; SCN5A; Sodium channel