title: Mechanical preconditioning enables electrophysiologic coupling of skeletal myoblast cells to myocardium.
abstract: OBJECTIVE
  The effect of mechanical preconditioning on skeletal myoblasts in engineered tissue constructs was investigated to resolve issues associated with conduction block between skeletal myoblast cells and cardiomyocytes.
  
  
  METHODS
  Murine skeletal myoblasts were used to generate engineered tissue constructs with or without application of mechanical strain. After in vitro myotube formation, engineered tissue constructs were co-cultured for 6 days with viable embryonic heart slices. With the use of sharp electrodes, electrical coupling between engineered tissue constructs and embryonic heart slices was assessed in the presence or absence of pharmacologic agents.
  
  
  RESULTS
  The isolation and expansion procedure for skeletal myoblasts resulted in high yields of homogeneously desmin-positive (97.1% ± 0.1%) cells. Mechanical strain was exerted on myotubes within engineered tissue constructs during gelation of the matrix, generating preconditioned engineered tissue constructs. Electrical coupling between preconditioned engineered tissue constructs and embryonic heart slices was observed; however, no coupling was apparent when engineered tissue constructs were not subjected to mechanical strain. Coupling of cells from engineered tissue constructs to cells in embryonic heart slices showed slower conduction velocities than myocardial cells with the embryonic heart slices (preconditioned engineered tissue constructs vs embryonic heart slices: 0.04 ± 0.02 ms vs 0.10 ± 0.05 ms, P = .011), lower maximum stimulation frequencies (preconditioned engineered tissue constructs vs embryonic heart slices: 4.82 ± 1.42 Hz vs 10.58 ± 1.56 Hz; P = .0009), and higher sensitivities to the gap junction inhibitor (preconditioned engineered tissue constructs vs embryonic heart slices: 0.22 ± 0.07 mmol/L vs 0.93 ± 0.15 mmol/L; P = .0004).
  
  
  CONCLUSIONS
  We have generated skeletal myoblast-based transplantable grafts that electrically couple to myocardium.
authors.affiliation: Department of Cardiac and Thoracic Surgery, Heart Center of the University, University of Cologne, Cologne, Germany.|Center for Molecular Medicine, University of Cologne, Cologne, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Neef
authors.affiliation: Department of Cardiac and Thoracic Surgery, Heart Center of the University, University of Cologne, Cologne, Germany.|Center for Molecular Medicine, University of Cologne, Cologne, Germany.
authors.forename: Yeong-Hoon
authors.initials: YH
authors.lastname: Choi
authors.affiliation: Department of Cardiac and Thoracic Surgery, Heart Center of the University, University of Cologne, Cologne, Germany.|Center for Molecular Medicine, University of Cologne, Cologne, Germany.
authors.forename: Sureshkumar Perumal
authors.initials: SP
authors.lastname: Srinivasan
authors.affiliation: Department of Cardiac and Thoracic Surgery, Heart Center of the University, University of Cologne, Cologne, Germany.|Center for Molecular Medicine, University of Cologne, Cologne, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Treskes
authors.affiliation: Department of Pediatric Cardiology, Heart Center of the University, University of Cologne, Cologne, Germany.
authors.forename: Douglas B
authors.initials: DB
authors.lastname: Cowan
authors.affiliation: Department of Anesthesiology, Perioperative and Pain Medicine, Children's Hospital Boston and Harvard Medical School, Boston, Mass.
authors.forename: Christof
authors.initials: C
authors.lastname: Stamm
authors.affiliation: Berlin-Brandenburg Center for Regenerative Therapies, Berlin, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Rubach
authors.affiliation: Berlin-Brandenburg Center for Regenerative Therapies, Berlin, Germany.
authors.forename: Roland
authors.initials: R
authors.lastname: Adelmann
authors.affiliation: Department of Cardiac and Thoracic Surgery, Heart Center of the University, University of Cologne, Cologne, Germany.|Center for Molecular Medicine, University of Cologne, Cologne, Germany.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Wittwer
authors.affiliation: Department of Cardiac and Thoracic Surgery, Heart Center of the University, University of Cologne, Cologne, Germany.|Center for Molecular Medicine, University of Cologne, Cologne, Germany.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Wahlers
mesh_terms: D000200:Action Potentials; D000818:Animals; D000831:Animals, Newborn; D015415:Biomarkers / Q000378:metabolism; D015820:Cadherins / Q000378:metabolism; D002469:Cell Separation; D002478:Cells, Cultured; D018920:Coculture Techniques; D017630:Connexins / Q000378:metabolism; D003893:Desmin / Q000378:metabolism; D004558:Electric Stimulation; D056966:Excitation Contraction Coupling / Q000187:drug effects; D017629:Gap Junctions / Q000187:drug effects / Q000502:physiology; D006321:Heart / Q000196:embryology*; D019850:Heptanol / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D018485:Muscle Fibers, Skeletal / Q000378:metabolism / Q000502:physiology*; D032448:Myoblasts, Skeletal / Q000378:metabolism / Q000502:physiology*; D009206:Myocardium / Q000378:metabolism; D013314:Stress, Mechanical; D013997:Time Factors; D023822:Tissue Engineering; D054457:Tissue Scaffolds
chemical_list: D015415:Biomarkers; D015820:Cadherins; C489083:Cdh2 protein, mouse; D017630:Connexins; D003893:Desmin; D019850:Heptanol