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(Circulation Research. 2007;100:1597.)
© 2007 American Heart Association, Inc.

Cellular Biology

Gene Transfer of Connexin43 Mutants Attenuates Coupling in Cardiomyocytes

Novel Basis for Modulation of Cardiac Conduction by Gene Therapy

Eddy Kizana, Connie Y. Chang, Eugenio Cingolani, Genaro A. Ramirez-Correa, Rajesh B. Sekar, M. Roselle Abraham, Samantha L. Ginn, Leslie Tung, Ian E. Alexander, Eduardo Marbán

From the Gene Therapy Research Unit of The Children’s Hospital at Westmead and Children’s Medical Research Institute (E.K., S.L.G., I.E.A.), Westmead, Australia; the Department of Biomedical Engineering (C.Y.C., R.B.S., L.T.) and the Division of Cardiology (E.K., C.Y.C., E.C., G.A.R.-C., M.R.A., E.M.), Johns Hopkins University, Baltimore, Md.

Correspondence to Eduardo Marbán, MD, PhD, 720 Rutland Avenue, Ross 858, Baltimore, MD 21205. E-mail marban{at}jhmi.edu

Modification of electrical conduction would be a useful principle to recruit in preventing or treating certain arrhythmias, notably ventricular tachycardia (VT). Here we pursue a novel gene transfer approach to modulate electrical conduction by reducing gap junctional intercellular communication (GJIC) and hence potentially modify the arrhythmia substrate. The ultimate goal is to develop a nondestructive approach to uncouple zones of slow conduction by focal gene transfer. Lentiviral vectors encoding connexin43 (Cx43) internal loop mutants were produced and studied in vitro. Transduction of neonatal rat ventricular myocytes (NRVMs) revealed the expected subcellular localization of the mutant gene product. Fluorescent dye transfer studies showed a significant reduction of GJIC in NRVMs that had been genetically modified. Additionally, adjacent mutant gene-modified NRVMs displayed delayed calcium transients, indicative of electrical uncoupling. Multi-site optical mapping of action potential (AP) propagation in gene-modified NRVM monolayers revealed a 3-fold slowing of conduction velocity (CV) relative to nontransduced NRVMs. In conclusion, lentiviral vector–mediated gene transfer of Cx43 mutants reduced GJIC in NRVMs. Electrical charge transfer was also reduced as evidenced by delayed calcium transients in adjacent NRVMs and reduced CV in NRVM monolayers. These data validate a molecular tool that opens the prospect for gene transfer targeting gap junctions as an approach to modulate cardiac conduction.

Key Words: gap junction • gene transfer • connexin43

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