Marc C Engels1, Saïd F A Askar1, Wanchana Jangsangthong1, Brian O Bingen1, Iolanda Feola1, Jia Liu1, Rupamanjari Majumder1, Michel I M Versteegh2, Jerry Braun2, Robert J M Klautz2, Dirk L Ypey1, Antoine A F De Vries1, Daniël A Pijnappels3. 1. Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, Albinusdreef 2, Leiden, RC 2300, The Netherlands. 2. Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, Albinusdreef 2, Leiden, RC 2300, The Netherlands Department of Cardiothoracic Surgery, Heart Lung Center Leiden, Leiden University Medical Center, Leiden, The Netherlands. 3. Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, Albinusdreef 2, Leiden, RC 2300, The Netherlands D.A.Pijnappels@lumc.nl.
Abstract
AIMS: Fibrosis increases arrhythmogenicity in myocardial tissue by causing structural and functional disruptions in the cardiac syncytium. Forced fusion of fibroblastic cells with adjacent cardiomyocytes may theoretically resolve these disruptions. Therefore, the electrophysiological effects of such electrical and structural integration of fibroblastic cells into a cardiac syncytium were studied. METHODS AND RESULTS: Human ventricular scar cells (hVSCs) were transduced with lentiviral vectors encoding enhanced green fluorescent protein alone (eGFP↑-hVSCs) or together with the fusogenic vesicular stomatitis virus G protein (VSV-G/eGFP↑-hVSCs) and subsequently co-cultured (1:4 ratio) with neonatal rat ventricular cardiomyocytes (NRVMs) in confluent monolayers yielding eGFP↑- and VSV-G/eGFP↑-co-cultures, respectively. Cellular fusion was induced by brief exposure to pH = 6.0 medium. Optical mapping experiments showed eGFP↑-co-cultures to be highly arrhythmogenic [43.3% early afterdepolarization (EAD) incidence vs. 7.7% in control NRVM cultures, P < 0.0001], with heterogeneous prolongation of action potential (AP) duration (APD). Fused VSV-G/eGFP↑-co-cultures displayed markedly lower EAD incidence (4.6%, P < 0.001) than unfused co-cultures, associated with decreases in APD, APD dispersion, and decay time of cytosolic Ca(2+) waves. Heterokaryons strongly expressed connexin43 (Cx43). Also, maximum diastolic potential in co-cultures was more negative after fusion, while heterokaryons exhibited diverse mixed NRVM/hVSC whole-cell current profiles, but consistently showed increased outward Kv currents compared with NRVMs or hVSCs. Inhibition of Kv channels by tetraethylammonium chloride abrogated the anti-arrhythmic effects of fusion in VSV-G/eGFP↑-co-cultures raising EAD incidence from 7.9 to 34.2% (P < 0.001). CONCLUSION: Forced fusion of cultured hVSCs with NRVMs yields electrically functional heterokaryons and reduces arrhythmogenicity by preventing EADs, which is, at least partly, attributable to increased repolarization force. Published on behalf of the European Society of Cardiology. All rights reserved.
AIMS: Fibrosis increases arrhythmogenicity in myocardial tissue by causing structural and functional disruptions in the cardiac syncytium. Forced fusion of fibroblastic cells with adjacent cardiomyocytes may theoretically resolve these disruptions. Therefore, the electrophysiological effects of such electrical and structural integration of fibroblastic cells into a cardiac syncytium were studied. METHODS AND RESULTS:Human ventricular scar cells (hVSCs) were transduced with lentiviral vectors encoding enhanced green fluorescent protein alone (eGFP↑-hVSCs) or together with the fusogenic vesicular stomatitis virus G protein (VSV-G/eGFP↑-hVSCs) and subsequently co-cultured (1:4 ratio) with neonatal rat ventricular cardiomyocytes (NRVMs) in confluent monolayers yielding eGFP↑- and VSV-G/eGFP↑-co-cultures, respectively. Cellular fusion was induced by brief exposure to pH = 6.0 medium. Optical mapping experiments showed eGFP↑-co-cultures to be highly arrhythmogenic [43.3% early afterdepolarization (EAD) incidence vs. 7.7% in control NRVM cultures, P < 0.0001], with heterogeneous prolongation of action potential (AP) duration (APD). Fused VSV-G/eGFP↑-co-cultures displayed markedly lower EAD incidence (4.6%, P < 0.001) than unfused co-cultures, associated with decreases in APD, APD dispersion, and decay time of cytosolic Ca(2+) waves. Heterokaryons strongly expressed connexin43 (Cx43). Also, maximum diastolic potential in co-cultures was more negative after fusion, while heterokaryons exhibited diverse mixed NRVM/hVSC whole-cell current profiles, but consistently showed increased outward Kv currents compared with NRVMs or hVSCs. Inhibition of Kv channels by tetraethylammonium chloride abrogated the anti-arrhythmic effects of fusion in VSV-G/eGFP↑-co-cultures raising EAD incidence from 7.9 to 34.2% (P < 0.001). CONCLUSION: Forced fusion of cultured hVSCs with NRVMs yields electrically functional heterokaryons and reduces arrhythmogenicity by preventing EADs, which is, at least partly, attributable to increased repolarization force. Published on behalf of the European Society of Cardiology. All rights reserved.
Authors: Markus Horsthemke; Lauryl M J Nutter; Anne C Bachg; Boris V Skryabin; Ulrike Honnert; Thomas Zobel; Sven Bogdan; Monika Stoll; Matthias D Seidl; Frank U Müller; Ursula Ravens; Andreas Unger; Wolfgang A Linke; Pim R R van Gorp; Antoine A F de Vries; Martin Bähler; Peter J Hanley Journal: J Biol Chem Date: 2019-02-08 Impact factor: 5.157
Authors: Alexander S Teplenin; Hans Dierckx; Antoine A F de Vries; Daniël A Pijnappels; Alexander V Panfilov Journal: Phys Rev X Date: 2018-06-26 Impact factor: 15.762