Christoph C Vogt1, Tobias Bruegmann1, Daniela Malan1, Annika Ottersbach2, Wilhelm Roell3, Bernd K Fleischmann1, Philipp Sasse4. 1. Institute of Physiology I, Life and Brain Center, University of Bonn, Sigmund-Freud-Str. 25, Bonn 53127, Germany. 2. Institute of Physiology I, Life and Brain Center, University of Bonn, Sigmund-Freud-Str. 25, Bonn 53127, Germany Department of Cardiac Surgery, University of Bonn, Bonn, Germany. 3. Department of Cardiac Surgery, University of Bonn, Bonn, Germany. 4. Institute of Physiology I, Life and Brain Center, University of Bonn, Sigmund-Freud-Str. 25, Bonn 53127, Germany philipp.sasse@uni-bonn.de.
Abstract
AIMS: Optogenetic pacing of the heart has been demonstrated in transgenic animals expressing channelrhodopsin-2 (ChR2). However, for the clinical use of optogenetics to treat cardiac arrhythmias, gene transfer to non-transgenic hearts is required. The aim of this study was to describe a reliable method for gene transfer of ChR2 into a sufficient percentage of cardiomyocytes to overcome the electrical sink of all the coupled non-expressing cardiomyocytes during optical pacing of the whole heart in vivo. METHODS AND RESULTS: Adeno-associated virus (AAV) with cardiac tropism for expression of ChR2 in fusion with mCherry was systemically injected into wild-type mouse hearts. Bright mCherry fluorescence was detected in the whole heart 4-10 weeks later. Single-cell dissociation revealed that on average 58% cardiomyocytes were mCherry-positive. These showed light-induced inward currents, action potentials, and contractions. Pulsed illumination of the left ventricle induced ventricular pacing in vivo in 74% of mice, and higher light intensities were required for reduced pulse duration or size of illumination. Non-responding hearts showed low AAV expression, and the threshold for optical pacing was estimated to be 35-40% ChR2-expressing cardiomyocytes. Optical pacing in vivo was stable over extended periods without negative effects on normal sinus rhythm and ECG parameters after termination of stimulation indicating sufficient cardiac output during pacing. CONCLUSIONS: Gene transfer generates sufficient ChR2 photocurrent for reliable optogenetic pacing in vivo and lays out the basis for future optogenetic pacemaker and pain-free defibrillation therapies. Published on behalf of the European Society of Cardiology. All rights reserved.
AIMS: Optogenetic pacing of the heart has been demonstrated in transgenic animals expressing channelrhodopsin-2 (ChR2). However, for the clinical use of optogenetics to treat cardiac arrhythmias, gene transfer to non-transgenic hearts is required. The aim of this study was to describe a reliable method for gene transfer of ChR2 into a sufficient percentage of cardiomyocytes to overcome the electrical sink of all the coupled non-expressing cardiomyocytes during optical pacing of the whole heart in vivo. METHODS AND RESULTS:Adeno-associated virus (AAV) with cardiac tropism for expression of ChR2 in fusion with mCherry was systemically injected into wild-type mouse hearts. Bright mCherry fluorescence was detected in the whole heart 4-10 weeks later. Single-cell dissociation revealed that on average 58% cardiomyocytes were mCherry-positive. These showed light-induced inward currents, action potentials, and contractions. Pulsed illumination of the left ventricle induced ventricular pacing in vivo in 74% of mice, and higher light intensities were required for reduced pulse duration or size of illumination. Non-responding hearts showed low AAV expression, and the threshold for optical pacing was estimated to be 35-40% ChR2-expressing cardiomyocytes. Optical pacing in vivo was stable over extended periods without negative effects on normal sinus rhythm and ECG parameters after termination of stimulation indicating sufficient cardiac output during pacing. CONCLUSIONS: Gene transfer generates sufficient ChR2 photocurrent for reliable optogenetic pacing in vivo and lays out the basis for future optogenetic pacemaker and pain-free defibrillation therapies. Published on behalf of the European Society of Cardiology. All rights reserved.
Authors: Tobias Bruegmann; Patrick M Boyle; Christoph C Vogt; Thomas V Karathanos; Hermenegild J Arevalo; Bernd K Fleischmann; Natalia A Trayanova; Philipp Sasse Journal: J Clin Invest Date: 2016-09-12 Impact factor: 14.808
Authors: Thomas V Karathanos; Jason D Bayer; Dafang Wang; Patrick M Boyle; Natalia A Trayanova Journal: J Physiol Date: 2016-04-24 Impact factor: 5.182