title: Light-induced termination of spiral wave arrhythmias by optogenetic engineering of atrial cardiomyocytes.
abstract: OBJECTIVE
  Atrial fibrillation (AF) is the most common cardiac arrhythmia and often involves reentrant electrical activation (e.g. spiral waves). Drug therapy for AF can have serious side effects including proarrhythmia, while electrical shock therapy is associated with discomfort and tissue damage. Hypothetically, forced expression and subsequent activation of light-gated cation channels in cardiomyocytes might deliver a depolarizing force sufficient for defibrillation, thereby circumventing the aforementioned drawbacks. We therefore investigated the feasibility of light-induced spiral wave termination through cardiac optogenetics.
  
  
  RESULTS
  Neonatal rat atrial cardiomyocyte monolayers were transduced with lentiviral vectors encoding light-activated Ca(2+)-translocating channelrhodopsin (CatCh; LV.CatCh∼eYFP↑) or eYFP (LV.eYFP↑) as control, and burst-paced to induce spiral waves rotating around functional cores. Effects of CatCh activation on reentry were investigated by optical and multi-electrode array (MEA) mapping. Western blot analyses and immunocytology confirmed transgene expression. Brief blue light pulses (10 ms/470 nm) triggered action potentials only in LV.CatCh∼eYFP↑-transduced cultures, confirming functional CatCh-mediated current. Prolonged light pulses (500 ms) resulted in reentry termination in 100% of LV.CatCh∼eYFP↑-transduced cultures (n = 31) vs. 0% of LV.eYFP↑-transduced cultures (n = 11). Here, CatCh activation caused uniform depolarization, thereby decreasing overall excitability (MEA peak-to-peak amplitude decreased 251.3 ± 217.1 vs. 9.2 ± 9.5 μV in controls). Consequently, functional coresize increased and phase singularities (PSs) drifted, leading to reentry termination by PS-PS or PS-boundary collisions.
  
  
  CONCLUSIONS
  This study shows that spiral waves in atrial cardiomyocyte monolayers can be terminated effectively by a light-induced depolarizing current, produced by the arrhythmogenic substrate itself, upon optogenetic engineering. These results provide proof-of-concept for shockless defibrillation.
authors.affiliation: Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, Albinusdreef 2, 2300 RC Leiden, the Netherlands.
authors.forename: Brian O
authors.initials: BO
authors.lastname: Bingen
authors.affiliation: Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, Albinusdreef 2, 2300 RC Leiden, the Netherlands.
authors.forename: Marc C
authors.initials: MC
authors.lastname: Engels
authors.affiliation: Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, Albinusdreef 2, 2300 RC Leiden, the Netherlands.
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Schalij
authors.affiliation: Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, Albinusdreef 2, 2300 RC Leiden, the Netherlands.
authors.forename: Wanchana
authors.initials: W
authors.lastname: Jangsangthong
authors.affiliation: Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, Albinusdreef 2, 2300 RC Leiden, the Netherlands.
authors.forename: Zeinab
authors.initials: Z
authors.lastname: Neshati
authors.affiliation: Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, Albinusdreef 2, 2300 RC Leiden, the Netherlands.
authors.forename: Iolanda
authors.initials: I
authors.lastname: Feola
authors.affiliation: Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, Albinusdreef 2, 2300 RC Leiden, the Netherlands.
authors.forename: Dirk L
authors.initials: DL
authors.lastname: Ypey
authors.affiliation: Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, Albinusdreef 2, 2300 RC Leiden, the Netherlands.
authors.forename: Saïd F A
authors.initials: SF
authors.lastname: Askar
authors.affiliation: Department of Physics and Astronomy, Ghent University, Ghent, Belgium.
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Panfilov
authors.affiliation: Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, Albinusdreef 2, 2300 RC Leiden, the Netherlands d.a.pijnappels@lumc.nl.
authors.forename: Daniël A
authors.initials: DA
authors.lastname: Pijnappels
authors.affiliation: Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, Albinusdreef 2, 2300 RC Leiden, the Netherlands.
authors.forename: Antoine A F
authors.initials: AA
authors.lastname: de Vries
mesh_terms: D000200:Action Potentials; D000818:Animals; D000831:Animals, Newborn; D001281:Atrial Fibrillation / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology / Q000628:therapy*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D015153:Blotting, Western; D002304:Cardiac Pacing, Artificial; D002478:Cells, Cultured; D000075402:Channelrhodopsins; D005240:Feasibility Studies; D005455:Fluorescent Antibody Technique; D005822:Genetic Vectors; D006325:Heart Atria / Q000378:metabolism / Q000503:physiopathology / Q000528:radiation effects; D016086:Lentivirus / Q000235:genetics; D008027:Light; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000378:metabolism / Q000528:radiation effects*; D062308:Optogenetics; D018408:Patch-Clamp Techniques; D017208:Rats, Wistar; D013997:Time Factors; D014161:Transduction, Genetic; D014162:Transfection; D056969:Voltage-Sensitive Dye Imaging
chemical_list: D001426:Bacterial Proteins; D000075402:Channelrhodopsins; D008164:Luminescent Proteins; C054562:yellow fluorescent protein, Bacteria
keywords: Atrial fibrillation; Cardiomyocyte; Lentiviral vector; Optical mapping; Optogenetics