title: Preconditioning of skeletal myoblast-based engineered tissue constructs enables functional coupling to myocardium in vivo.
abstract: OBJECTIVE
  Skeletal myoblasts fuse to form functional syncytial myotubes as an integral part of the skeletal muscle. During this differentiation process, expression of proteins for mechanical and electrical integration is seized, which is a major drawback for the application of skeletal myoblasts in cardiac regenerative cell therapy, because global heart function depends on intercellular communication.
  
  
  METHODS
  Mechanically preconditioned engineered tissue constructs containing neonatal mouse skeletal myoblasts were transplanted epicardially. A Y-chromosomal specific polymerase chain reaction (PCR) was undertaken up to 10 weeks after transplantation to confirm the presence of grafted cells. Histologic and electrophysiologic analyses were carried out 1 week after transplantation.
  
  
  RESULTS
  Cells within the grafted construct expressed connexin 43 at the interface to the host myocardium, indicating electrical coupling, confirmed by sharp electrode recordings. Analyses of the maximum stimulation frequency (5.65 ± 0.37 Hz), conduction velocity (0.087 ± 0.011 m/s) and sensitivity for pharmacologic conduction block (0.736 ± 0.080 mM 1-heptanol) revealed effective electrophysiologic coupling between graft and host cells, although significantly less robust than in native myocardial tissue (maximum stimulation frequency, 11.616 ± 0.238 Hz, P < .001; conduction velocity, 0.300 ± 0.057 m/s, P < .01; conduction block, 1.983 ± 0.077 mM 1-heptanol, P < .001).
  
  
  CONCLUSIONS
  Although untreated skeletal myoblasts cannot couple to cardiomyocytes, we confirm that mechanical preconditioning enables transplanted skeletal myoblasts to functionally interact with cardiomyocytes in vivo and, thus, reinvigorate the concept of skeletal myoblast-based cardiac cell therapy.
authors.affiliation: Department of Cardiothoracic Surgery, Heart Center, University of Cologne, Cologne, Germany; Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany; Institute for Neurophysiology, University of Cologne, Cologne, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Treskes
authors.affiliation: Department of Cardiothoracic Surgery, Heart Center, University of Cologne, Cologne, Germany; Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Neef
authors.affiliation: Department of Cardiothoracic Surgery, Heart Center, University of Cologne, Cologne, Germany; Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany; Institute for Neurophysiology, University of Cologne, Cologne, Germany.
authors.forename: Sureshkumar
authors.initials: S
authors.lastname: Perumal Srinivasan
authors.affiliation: Institute for Neurophysiology, University of Cologne, Cologne, Germany; Department of Internal Medicine III, Heart Center, University of Cologne, Cologne, Germany.
authors.forename: Marcel
authors.initials: M
authors.lastname: Halbach
authors.affiliation: Berlin-Brandenburg Center for Regenerative Therapies, Berlin, Germany.
authors.forename: Christof
authors.initials: C
authors.lastname: Stamm
authors.affiliation: Departments of Anesthesiology and Perioperative and Pain Medicine, Children's Hospital Boston and Harvard Medical School, Boston, Mass.
authors.forename: Douglas
authors.initials: D
authors.lastname: Cowan
authors.affiliation: Department of Cardiothoracic Surgery, Heart Center, University of Cologne, Cologne, Germany.
authors.forename: Maximilian
authors.initials: M
authors.lastname: Scherner
authors.affiliation: Department of Cardiothoracic Surgery, Heart Center, University of Cologne, Cologne, Germany.
authors.forename: Navid
authors.initials: N
authors.lastname: Madershahian
authors.affiliation: Department of Cardiothoracic Surgery, Heart Center, University of Cologne, Cologne, Germany.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Wittwer
authors.affiliation: Institute for Neurophysiology, University of Cologne, Cologne, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Hescheler
authors.affiliation: Department of Cardiothoracic Surgery, Heart Center, University of Cologne, Cologne, Germany; Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Wahlers
authors.affiliation: Department of Cardiothoracic Surgery, Heart Center, University of Cologne, Cologne, Germany; Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany. Electronic address: yh.choi@uk-koeln.de.
authors.forename: Yeong-Hoon
authors.initials: YH
authors.lastname: Choi
mesh_terms: D000200:Action Potentials; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002450:Cell Communication; D018929:Cell Culture Techniques; D002470:Cell Survival; D002478:Cells, Cultured; D033481:Chromosomes, Mammalian; D018031:Connexin 43 / Q000378:metabolism; D056966:Excitation Contraction Coupling; D005260:Female; D008810:Mice, Inbred C57BL; D032448:Myoblasts, Skeletal / Q000378:metabolism* / Q000637:transplantation*; D009200:Myocardial Contraction; D032383:Myocytes, Cardiac / Q000378:metabolism*; D013314:Stress, Mechanical; D013997:Time Factors; D023822:Tissue Engineering / Q000379:methods*; D014998:Y Chromosome
chemical_list: D015415:Biomarkers; D018031:Connexin 43; C543076:GJA1 protein, mouse