title: Evaluation of frequency, type, and function of gap junctions between skeletal myoblasts overexpressing connexin43 and cardiomyocytes: relevance to cell transplantation.
abstract: Cell transplantation of skeletal myoblasts (SMs) is one possible treatment for repairing cardiac tissue after myocardial injury. However, inappropriate electrical coupling between grafted SMs and host cardiomyocytes may be responsible for the arrhythmias observed in clinical trials of SM transplantation. Whether functional gap junctions occur between the two cell types remains controversial. We have studied the ability of SMs to electrically couple with isolated adult rat cardiomyocytes (CMs) and assessed whether connexin43 (Cx43) overexpression enhanced gap junctional conductance (Gj). C2C12 myoblast lines overexpressing Cx43 were generated by gene transfection and clonal selection. CMs were cocultured with either SMs overexpressing Cx43 (CM-SM(Cx43)) or control SMs (CM-SM(WT)) in vitro. Gj between pairs of SMs and CMs was quantified with dual whole cell patch clamping. Formation of Gj occurred between 22% of CM-SM(WT) pairs (n=73) and 48% of CM-SM(Cx43) pairs (n=71, P<0.001). The Gj of CM-SM(Cx43) pairs (29.7+/-4.3 nS, n=21) was greater than that of CM-SM(WT) pairs (14.8+/-2.0 nS, n=12, P<0.05). The overexpression of Cx43 in SMs increased the formation of electrical communication and the steady-state conductance between SMs and CMs. Enhanced gap junctional conductance may be useful to promote the integration of transplanted SMs into the myocardium.
authors.affiliation: Cellular Electrophysiology, Heart Science Centre, National Heart & Lung Institute, Imperial College London, Harefield Hospital, London, UK. m.stagg@imperial.ac.uk
authors.forename: Mark A
authors.initials: MA
authors.lastname: Stagg
authors.forename: Steven R
authors.initials: SR
authors.lastname: Coppen
authors.forename: Ken
authors.initials: K
authors.lastname: Suzuki
authors.forename: Anabel
authors.initials: A
authors.lastname: Varela-Carver
authors.forename: Joon
authors.initials: J
authors.lastname: Lee
authors.forename: Nigel J
authors.initials: NJ
authors.lastname: Brand
authors.forename: Satsuki
authors.initials: S
authors.lastname: Fukushima
authors.forename: Magdi H
authors.initials: MH
authors.lastname: Yacoub
authors.forename: Cesare M N
authors.initials: CM
authors.lastname: Terracciano
mesh_terms: D000818:Animals; D002450:Cell Communication; D017690:Cell Transplantation; D002478:Cells, Cultured; D018920:Coculture Techniques; D018031:Connexin 43 / Q000378:metabolism*; D004553:Electric Conductivity; D017629:Gap Junctions / Q000502:physiology*; D008297:Male; D051379:Mice; D032448:Myoblasts, Skeletal / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D018031:Connexin 43