1
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Li TC, Zhong W, Ai BQ, Zhu WJ, Li BW, Panfilov AV, Dierckx H. Reordering and synchronization of electrical turbulence in cardiac tissue through global and partial optogenetical illumination. Phys Rev E 2023; 108:034218. [PMID: 37849154 DOI: 10.1103/physreve.108.034218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Accepted: 09/06/2023] [Indexed: 10/19/2023]
Abstract
Electrical turbulence in the heart is considered the culprit of cardiac disease, including the fatal ventricular fibrillation. Optogenetics is an emerging technology that has the capability to produce action potentials of cardiomyocytes to affect the electric wave propagation in cardiac tissue, thereby possessing the potential to control the turbulence, by shining a rotating spiral pattern onto the tissue. In this paper, we present a method to reorder and synchronize electrical turbulence through optogenetics. A generic two-variable reaction-diffusion model and a simplified three-variable ionic cardiac model are used. We discuss cases involving either global or partial illumination.
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Affiliation(s)
- Teng-Chao Li
- School of Physics, Hangzhou Normal University, Hangzhou 311121, China and School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006, China
| | - Wei Zhong
- School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006, China
| | - Bao-Quan Ai
- School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006, China
| | - Wei-Jing Zhu
- School of Photoelectric Engineering, Guangdong Polytechnic Normal University, Guangzhou 510665, China
| | - Bing-Wei Li
- School of Physics, Hangzhou Normal University, Hangzhou 311121, China
| | - Alexander V Panfilov
- Ural Federal University, Biomed Laboratory, 620002 Ekaterinburg, Russia; Department of Physics and Astronomy, Ghent University, B-9000 Ghent, Belgium; and World-Class Research Center "Digital biodesign and personalized healthcare", I.M. Sechenov First Moscow State Medical University, 119991 Moscow, Russia
| | - Hans Dierckx
- KU Leuven Campus Kortrijk-Kulak, Department of Mathematics, Etienne Sabbelaan 53 bus 7657, 8500 Kortrijk, Belgium and iSi Health - KU Leuven Institute of Physics-based Modeling for In Silico Health, KU Leuven, Belgium
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2
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Zhan H, Wang Z, Lin J, Yu Y, Xia L. Optogenetic actuation in ChR2-transduced fibroblasts alter excitation-contraction coupling and mechano-electric feedback in coupled cardiomyocytes: a computational modeling study. MATHEMATICAL BIOSCIENCES AND ENGINEERING : MBE 2021; 18:8354-8373. [PMID: 34814303 DOI: 10.3934/mbe.2021414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
With the help of the conventional electrical method and the growing optogenetic technology, cardiac fibroblasts (Fbs) have been verified to couple electrically with working myocytes and bring electrophysiological remodeling changes in them. The intrinsic properties of cardiac functional autoregulation represented by excitation-contraction coupling (ECC) and mechano-electric feedback (MEF) have also been extensively studied. However, the roles of optogenetic stimulation on the characteristics of ECC and MEF in cardiomyocytes (CMs) coupled with Fbs have been barely investigated. In this study, we proposed a combined model composed of three modules to explore these influences. Simulation results showed that (1) during ECC, an increased light duration (LD) strengthened the inflow of ChR2 current and prolonged action potential duration (APD), and extended durations of twitch and internal sarcomere deformation through the decreased dissociation of calcium with troponin C (CaTnC) complexes and the prolonged duration of Xb attachment-detachment; (2) during MEF, an increased LD was followed by a longer muscle twitch and deformation, and led to APD prolongation through the inward ChR2 current and its inward rectification kinetics, which far outweighed the effects of the delaying dissociation of CaTnC complexes and the prolonged reverse mode of Na+-Ca2+ exchange on AP shortening; (3) due to the ChR2 current's rectification feature, enhancing the light irradiance (LI) brought slight variations in peak or valley values of electrophysiological and mechanical parameters while did not change durations of AP and twitch and muscle deformation in both ECC and MEF. In conclusion, the inward ChR2 current and its inward rectification feature were found to affect significantly the durations of AP and twitch in both ECC and MEF. The roles of optogenetic actuation on both ECC and MEF should be considered in future cardiac computational optogenetics at the tissue and organ scale.
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Affiliation(s)
- Heqing Zhan
- College of Biomedical Information and Engineering, Hainan Medical University, Haikou, China
- Key Laboratory of Emergency and Trauma of Ministry of Education, Hainan Medical University, Haikou, China
| | - Zefeng Wang
- Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, Beijing, China
| | - Jialun Lin
- College of Biomedical Information and Engineering, Hainan Medical University, Haikou, China
| | - Yuanbo Yu
- College of Biomedical Information and Engineering, Hainan Medical University, Haikou, China
| | - Ling Xia
- Key Laboratory for Biomedical Engineering of Ministry of Education, Institute of Biomedical Engineering, Zhejiang University, Hangzhou, China
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3
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Ochs AR, Karathanos TV, Trayanova NA, Boyle PM. Optogenetic Stimulation Using Anion Channelrhodopsin (GtACR1) Facilitates Termination of Reentrant Arrhythmias With Low Light Energy Requirements: A Computational Study. Front Physiol 2021; 12:718622. [PMID: 34526912 PMCID: PMC8435849 DOI: 10.3389/fphys.2021.718622] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 07/23/2021] [Indexed: 12/24/2022] Open
Abstract
Optogenetic defibrillation of hearts expressing light-sensitive cation channels (e.g., ChR2) has been proposed as an alternative to conventional electrotherapy. Past modeling work has shown that ChR2 stimulation can depolarize enough myocardium to interrupt arrhythmia, but its efficacy is limited by light attenuation and high energy needs. These shortcomings may be mitigated by using new optogenetic proteins like Guillardia theta Anion Channelrhodopsin (GtACR1), which produces a repolarizing outward current upon illumination. Accordingly, we designed a study to assess the feasibility of GtACR1-based optogenetic arrhythmia termination in human hearts. We conducted electrophysiological simulations in MRI-based atrial or ventricular models (n = 3 each), with pathological remodeling from atrial fibrillation or ischemic cardiomyopathy, respectively. We simulated light sensitization via viral gene delivery of three different opsins (ChR2, red-shifted ChR2, GtACR1) and uniform endocardial illumination at the appropriate wavelengths (blue, red, or green light, respectively). To analyze consistency of arrhythmia termination, we varied pulse timing (three evenly spaced intervals spanning the reentrant cycle) and intensity (atrial: 0.001–1 mW/mm2; ventricular: 0.001–10 mW/mm2). In atrial models, GtACR1 stimulation with 0.005 mW/mm2 green light consistently terminated reentry; this was 10–100x weaker than the threshold levels for ChR2-mediated defibrillation. In ventricular models, defibrillation was observed in 2/3 models for GtACR1 stimulation at 0.005 mW/mm2 (100–200x weaker than ChR2 cases). In the third ventricular model, defibrillation failed in nearly all cases, suggesting that attenuation issues and patient-specific organ/scar geometry may thwart termination in some cases. Across all models, the mechanism of GtACR1-mediated defibrillation was voltage forcing of illuminated tissue toward the modeled channel reversal potential of −40 mV, which made propagation through affected regions impossible. Thus, our findings suggest GtACR1-based optogenetic defibrillation of the human heart may be feasible with ≈2–3 orders of magnitude less energy than ChR2.
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Affiliation(s)
- Alexander R Ochs
- Department of Bioengineering, University of Washington, Seattle, WA, United States
| | - Thomas V Karathanos
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, United States
| | - Natalia A Trayanova
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, United States.,Alliance for Cardiovascular Diagnostic and Treatment Innovation, Johns Hopkins University, Baltimore, MD, United States
| | - Patrick M Boyle
- Department of Bioengineering, University of Washington, Seattle, WA, United States.,Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, United States.,Center for Cardiovascular Biology, University of Washington, Seattle, WA, United States
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4
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Sung E, Etoz S, Zhang Y, Trayanova NA. Whole-heart ventricular arrhythmia modeling moving forward: Mechanistic insights and translational applications. BIOPHYSICS REVIEWS 2021; 2:031304. [PMID: 36281224 PMCID: PMC9588428 DOI: 10.1063/5.0058050] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/19/2023]
Abstract
Ventricular arrhythmias are the primary cause of sudden cardiac death and one of the leading causes of mortality worldwide. Whole-heart computational modeling offers a unique approach for studying ventricular arrhythmias, offering vast potential for developing both a mechanistic understanding of ventricular arrhythmias and clinical applications for treatment. In this review, the fundamentals of whole-heart ventricular modeling and current methods of personalizing models using clinical data are presented. From this foundation, the authors summarize recent advances in whole-heart ventricular arrhythmia modeling. Efforts in gaining mechanistic insights into ventricular arrhythmias are discussed, in addition to other applications of models such as the assessment of novel therapeutics. The review emphasizes the unique benefits of computational modeling that allow for insights that are not obtainable by contemporary experimental or clinical means. Additionally, the clinical impact of modeling is explored, demonstrating how patient care is influenced by the information gained from ventricular arrhythmia models. The authors conclude with future perspectives about the direction of whole-heart ventricular arrhythmia modeling, outlining how advances in neural network methodologies hold the potential to reduce computational expense and permit for efficient whole-heart modeling.
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Affiliation(s)
- Eric Sung
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA
- Alliance for Cardiovascular Diagnostic and Treatment Innovation, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Sevde Etoz
- Alliance for Cardiovascular Diagnostic and Treatment Innovation, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Yingnan Zhang
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA
- Alliance for Cardiovascular Diagnostic and Treatment Innovation, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Natalia A. Trayanova
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA
- Alliance for Cardiovascular Diagnostic and Treatment Innovation, Johns Hopkins University, Baltimore, Maryland 21218, USA
- Author to whom correspondence should be addressed: . Tel.: 410-516-4375
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Boyle PM, Yu J, Klimas A, Williams JC, Trayanova NA, Entcheva E. OptoGap is an optogenetics-enabled assay for quantification of cell-cell coupling in multicellular cardiac tissue. Sci Rep 2021; 11:9310. [PMID: 33927252 PMCID: PMC8085001 DOI: 10.1038/s41598-021-88573-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 03/31/2021] [Indexed: 12/23/2022] Open
Abstract
Intercellular electrical coupling is an essential means of communication between cells. It is important to obtain quantitative knowledge of such coupling between cardiomyocytes and non-excitable cells when, for example, pathological electrical coupling between myofibroblasts and cardiomyocytes yields increased arrhythmia risk or during the integration of donor (e.g., cardiac progenitor) cells with native cardiomyocytes in cell-therapy approaches. Currently, there is no direct method for assessing heterocellular coupling within multicellular tissue. Here we demonstrate experimentally and computationally a new contactless assay for electrical coupling, OptoGap, based on selective illumination of inexcitable cells that express optogenetic actuators and optical sensing of the response of coupled excitable cells (e.g., cardiomyocytes) that are light-insensitive. Cell-cell coupling is quantified by the energy required to elicit an action potential via junctional current from the light-stimulated cell(s). The proposed technique is experimentally validated against the standard indirect approach, GapFRAP, using light-sensitive cardiac fibroblasts and non-transformed cardiomyocytes in a two-dimensional setting. Its potential applicability to the complex three-dimensional setting of the native heart is corroborated by computational modelling and proper calibration. Lastly, the sensitivity of OptoGap to intrinsic cell-scale excitability is robustly characterized via computational analysis.
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Affiliation(s)
- Patrick M Boyle
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
- Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD, USA
- Department of Bioengineering, University of Washington, Seattle, WA, USA
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
- Center for Cardiovascular Biology, University of Washington, Seattle, WA, USA
| | - Jinzhu Yu
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA
| | - Aleksandra Klimas
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA
- Department of Biomedical Engineering, George Washington University, 800 22nd Street NW, Suite 5000, Washington, DC, 20052, USA
| | - John C Williams
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA
| | - Natalia A Trayanova
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
- Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD, USA
- Alliance for Cardiovascular Diagnostic and Treatment Innovation, Johns Hopkins University, Baltimore, MD, USA
| | - Emilia Entcheva
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA.
- Department of Biomedical Engineering, George Washington University, 800 22nd Street NW, Suite 5000, Washington, DC, 20052, USA.
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6
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Wang X, Cheng Y. Optical Manipulation of Perfused Mouse Heart Expressing Channelrhodopsin-2 in Rhythm Control. Methods Mol Biol 2021; 2191:377-390. [PMID: 32865755 DOI: 10.1007/978-1-0716-0830-2_21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
Optogenetics is a new approach using light intensity to modulate the electrical activity of excitable cells by the interaction of light-sensitive proteins. This method has been widely and enthusiastically utilized in some fields over the last decade. Localizing a photosensitive protein to a specific place in the membrane of cardiomyocytes at a specific time is essential for most biological processes. In this case, vectors are injected into the circulation to allow them to spread throughout the whole heart. The aim of this protocol is to perform different illumination modes with blue laser to investigate optical control of Langendorff-perfused mice hearts which were systematically injected with adeno-associated virus (AAV) for ChR2(H134R) gene transfer. Electrograms (EGs) and epicardium monophasic action potential (MAP) showed that ChR2 expression in the heart can be flexibly controlled by blue light across different illumination sites with corresponding triggered ectopic rhythm. Illumination intensity, pulse duration, and impulse frequency were associated with the light capture rate. Flexible control of the cardiac rhythm with optogenetics provides an innovative approach to cardiac research and therapy.
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Affiliation(s)
- Xi Wang
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, People's Republic of China. .,Cardiovascular Research Institute, Wuhan University, Wuhan, People's Republic of China. .,Hubei Key Laboratory of Cardiology, Wuhan, People's Republic of China.
| | - Yue Cheng
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, People's Republic of China.,Cardiovascular Research Institute, Wuhan University, Wuhan, People's Republic of China.,Hubei Key Laboratory of Cardiology, Wuhan, People's Republic of China
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7
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Abstract
The electromechanical function of the heart involves complex, coordinated activity over time and space. Life-threatening cardiac arrhythmias arise from asynchrony in these space-time events; therefore, therapies for prevention and treatment require fundamental understanding and the ability to visualize, perturb and control cardiac activity. Optogenetics combines optical and molecular biology (genetic) approaches for light-enabled sensing and actuation of electrical activity with unprecedented spatiotemporal resolution and parallelism. The year 2020 marks a decade of developments in cardiac optogenetics since this technology was adopted from neuroscience and applied to the heart. In this Review, we appraise a decade of advances that define near-term (immediate) translation based on all-optical electrophysiology, including high-throughput screening, cardiotoxicity testing and personalized medicine assays, and long-term (aspirational) prospects for clinical translation of cardiac optogenetics, including new optical therapies for rhythm control. The main translational opportunities and challenges for optogenetics to be fully embraced in cardiology are also discussed.
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8
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Bansal H, Gupta N, Roy S. Theoretical Analysis of Low-power Bidirectional Optogenetic Control of High-frequency Neural Codes with Single Spike Resolution. Neuroscience 2020; 449:165-188. [DOI: 10.1016/j.neuroscience.2020.09.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 09/04/2020] [Accepted: 09/07/2020] [Indexed: 02/06/2023]
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9
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Cardiac Optogenetics in Atrial Fibrillation: Current Challenges and Future Opportunities. BIOMED RESEARCH INTERNATIONAL 2020; 2020:8814092. [PMID: 33195698 PMCID: PMC7641281 DOI: 10.1155/2020/8814092] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 10/07/2020] [Indexed: 12/23/2022]
Abstract
Although rarely life-threatening on short term, atrial fibrillation leads to increased mortality and decreased quality of life through its complications, including heart failure and stroke. Recent studies highlight the benefits of maintaining sinus rhythm. However, pharmacological long-term rhythm control strategies may be shadowed by associated proarrhythmic effects. At the same time, electrical cardioversion is limited to hospitals, while catheter ablation therapy, although effective, is invasive and is dedicated to specific patients, usually with low amounts of atrial fibrosis (preferably Utah I-II). Cardiac optogenetics allows influencing the heart's electrical activity by applying specific wavelength light pulses to previously engineered cardiomyocytes into expressing microbial derived light-sensitive proteins called opsins. The resulting ion influx may give rise to either hyperpolarizing or depolarizing currents, thus offering a therapeutic potential in cardiac electrophysiology, including pacing, resynchronization, and arrhythmia termination. Optogenetic atrial fibrillation cardioversion might be achieved by inducing a conduction block or filling of the excitable gap. The authors agree that transmural opsin expression and appropriate illumination with an exposure time longer than the arrhythmia cycle length are necessary to achieve successful arrhythmia termination. However, the efficiency and safety of biological cardioversion in humans remain to be seen, as well as side effects such as immune reactions and loss of opsin expression. The possibility of delivering pain-free shocks with out-of-hospital biological cardioversion is tempting; however, there are several issues that need to be addressed first: applicability and safety in humans, long-term behaviour, anticoagulation requirements, and fibrosis interactions.
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10
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Gruber A, Edri O, Gepstein L. Cardiac optogenetics: the next frontier. Europace 2019; 20:1910-1918. [PMID: 29315402 DOI: 10.1093/europace/eux371] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Accepted: 12/14/2017] [Indexed: 12/21/2022] Open
Abstract
The emerging technology of optogenetics uses optical and genetic means to monitor and modulate the electrophysiological properties of excitable tissues. While transforming the field of neuroscience, the technology has recently gained popularity also in the cardiac arena. Here, we describe the basic principles of optogenetics, the available and evolving optogenetic tools, and the unique potential of this technology for basic and translational cardiac electrophysiology. Specifically, we discuss the ability to control (augment or suppress) the cardiac tissue's excitable properties using optogenetic actuators (microbial opsins), which are light-gated ion channels and pumps that can cause light-triggered membrane depolarization or hyperpolarization. We then focus on the potential clinical implications of this technology for the treatment of cardiac arrhythmias by describing recent efforts for developing optogenetic-based cardiac pacing, resynchronization, and defibrillation experimental strategies. Finally, the significant obstacles and challenges that need to be overcome before any future clinical translation can be expected are discussed.
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Affiliation(s)
- Amit Gruber
- The Sohnis Family Reaserch Laboratory for Cardiac Electrophysiology and Regenerative Medicine, Rappaport Faculty of Medicine and Research Institute, Technion- Israel Institute of Technology, Haifa, Israel
| | - Oded Edri
- The Sohnis Family Reaserch Laboratory for Cardiac Electrophysiology and Regenerative Medicine, Rappaport Faculty of Medicine and Research Institute, Technion- Israel Institute of Technology, Haifa, Israel
| | - Lior Gepstein
- The Sohnis Family Reaserch Laboratory for Cardiac Electrophysiology and Regenerative Medicine, Rappaport Faculty of Medicine and Research Institute, Technion- Israel Institute of Technology, Haifa, Israel.,Cardiology Department of Rambam Health Care Campus, HaAliya HaShniya St 8, Haifa, Israel
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11
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Jiang C, Li HT, Zhou YM, Wang X, Wang L, Liu ZQ. Cardiac optogenetics: a novel approach to cardiovascular disease therapy. Europace 2019; 20:1741-1749. [PMID: 29253159 DOI: 10.1093/europace/eux345] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Accepted: 10/24/2017] [Indexed: 12/13/2022] Open
Abstract
Optogenetics is a cell-type specific and high spatial-temporal resolution method that combines genetic encoding of light-sensitive proteins and optical manipulation techniques. Optogenetics technology provides a novel approach for research on cardiac arrhythmia treatment, including pacing, recovering the conduction system, and achieving cardiac resynchronization with precise and low-energy optical control. Photosensitive proteins, which usually act as ion channels, pumps, or receptors, are delivered to target cells, where they respond to light pulses of specific wavelengths, evoke transient flows of transmembrane ion currents, and induce signal transmission. With the development of gene technology, the in vivo efficiency of optogenetics in cardiology has been trialed, and in vitro experiments have been performed to test its potential in cardiac electrophysiology. Challenges for applying optogenetics in large animals and humans include the effectiveness, safety, and long-term expression of photosensitive proteins, unscattered and unattenuated exogenous light stimulation, and the need for implantable miniature light stimulators. Photosensitive proteins, genetic engineering technology, and light equipment are essential for experiments in cardiac optogenetics. Optogenetics may provide an alternative method for evaluating the mechanism of cardiac arrhythmias, testing hypotheses, and treating cardiovascular diseases.
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Affiliation(s)
- Chan Jiang
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, PR China.,Cardiovascular Research Institute, Wuhan University, Wuhan, PR China.,Hubei Key Laboratory of Cardiology, Wuhan, PR China
| | - Hai Tao Li
- Department of Cardiology, Hainan General Hospital, Haikou, PR China
| | - Yong Ming Zhou
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, PR China.,Cardiovascular Research Institute, Wuhan University, Wuhan, PR China.,Hubei Key Laboratory of Cardiology, Wuhan, PR China
| | - Xi Wang
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, PR China.,Cardiovascular Research Institute, Wuhan University, Wuhan, PR China.,Hubei Key Laboratory of Cardiology, Wuhan, PR China
| | - Long Wang
- Cardiovascular Research Institute, Wuhan University, Wuhan, PR China.,Hubei Key Laboratory of Cardiology, Wuhan, PR China.,Department of Anesthesiology, Renmin Hospital of Wuhan University, Wuhan, PR China
| | - Zi Qiang Liu
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, PR China.,Cardiovascular Research Institute, Wuhan University, Wuhan, PR China.,Hubei Key Laboratory of Cardiology, Wuhan, PR China
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12
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Sasse P, Funken M, Beiert T, Bruegmann T. Optogenetic Termination of Cardiac Arrhythmia: Mechanistic Enlightenment and Therapeutic Application? Front Physiol 2019; 10:675. [PMID: 31244670 PMCID: PMC6563676 DOI: 10.3389/fphys.2019.00675] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Accepted: 05/13/2019] [Indexed: 01/08/2023] Open
Abstract
Optogenetic methods enable selective de- and hyperpolarization of cardiomyocytes expressing light-sensitive proteins within the myocardium. By using light, this technology provides very high spatial and temporal precision, which is in clear contrast to electrical stimulation. In addition, cardiomyocyte-specific expression would allow pain-free stimulation. In light of these intrinsic technical advantages, optogenetic methods provide an intriguing opportunity to understand and improve current strategies to terminate cardiac arrhythmia as well as for possible pain-free arrhythmia termination in patients in the future. In this review, we give a concise introduction to optogenetic stimulation of cardiomyocytes and the whole heart and summarize the recent progress on optogenetic defibrillation and cardioversion to terminate cardiac arrhythmia. Toward this aim, we specifically focus on the different mechanisms of optogenetic arrhythmia termination and how these might influence the prerequisites for success. Furthermore, we critically discuss the clinical perspectives and potential patient populations, which might benefit from optogenetic defibrillation devices.
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Affiliation(s)
- Philipp Sasse
- Institute of Physiology I, Medical Faculty, University of Bonn, Bonn, Germany
| | - Maximilian Funken
- Institute of Physiology I, Medical Faculty, University of Bonn, Bonn, Germany.,Department of Internal Medicine II, University Hospital Bonn, University of Bonn, Bonn, Germany
| | - Thomas Beiert
- Department of Internal Medicine II, University Hospital Bonn, University of Bonn, Bonn, Germany
| | - Tobias Bruegmann
- Institute of Physiology I, Medical Faculty, University of Bonn, Bonn, Germany.,Research Training Group 1873, University of Bonn, Bonn, Germany.,Institute of Cardiovascular Physiology, University Medical Center, Georg August University Göttingen, Göttingen, Germany.,German Center for Cardiovascular Research (DZHK), Partner site Göttingen, Göttingen, Germany
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13
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Flexible and precise control of cardiac rhythm with blue light. Biochem Biophys Res Commun 2019; 514:759-764. [DOI: 10.1016/j.bbrc.2019.05.035] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Accepted: 05/04/2019] [Indexed: 12/24/2022]
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14
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Scardigli M, Müllenbroich C, Margoni E, Cannazzaro S, Crocini C, Ferrantini C, Coppini R, Yan P, Loew LM, Campione M, Bocchi L, Giulietti D, Cerbai E, Poggesi C, Bub G, Pavone FS, Sacconi L. Real-time optical manipulation of cardiac conduction in intact hearts. J Physiol 2018; 596:3841-3858. [PMID: 29989169 PMCID: PMC6117584 DOI: 10.1113/jp276283] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 07/05/2018] [Indexed: 11/28/2022] Open
Abstract
Key points Although optogenetics has clearly demonstrated the feasibility of cardiac manipulation, current optical stimulation strategies lack the capability to react acutely to ongoing cardiac wave dynamics. Here, we developed an all‐optical platform to monitor and control electrical activity in real‐time. The methodology was applied to restore normal electrical activity after atrioventricular block and to manipulate the intraventricular propagation of the electrical wavefront. The closed‐loop approach was also applied to simulate a re‐entrant circuit across the ventricle. The development of this innovative optical methodology provides the first proof‐of‐concept that a real‐time all‐optical stimulation can control cardiac rhythm in normal and abnormal conditions.
Abstract Optogenetics has provided new insights in cardiovascular research, leading to new methods for cardiac pacing, resynchronization therapy and cardioversion. Although these interventions have clearly demonstrated the feasibility of cardiac manipulation, current optical stimulation strategies do not take into account cardiac wave dynamics in real time. Here, we developed an all‐optical platform complemented by integrated, newly developed software to monitor and control electrical activity in intact mouse hearts. The system combined a wide‐field mesoscope with a digital projector for optogenetic activation. Cardiac functionality could be manipulated either in free‐run mode with submillisecond temporal resolution or in a closed‐loop fashion: a tailored hardware and software platform allowed real‐time intervention capable of reacting within 2 ms. The methodology was applied to restore normal electrical activity after atrioventricular block, by triggering the ventricle in response to optically mapped atrial activity with appropriate timing. Real‐time intraventricular manipulation of the propagating electrical wavefront was also demonstrated, opening the prospect for real‐time resynchronization therapy and cardiac defibrillation. Furthermore, the closed‐loop approach was applied to simulate a re‐entrant circuit across the ventricle demonstrating the capability of our system to manipulate heart conduction with high versatility even in arrhythmogenic conditions. The development of this innovative optical methodology provides the first proof‐of‐concept that a real‐time optically based stimulation can control cardiac rhythm in normal and abnormal conditions, promising a new approach for the investigation of the (patho)physiology of the heart. Although optogenetics has clearly demonstrated the feasibility of cardiac manipulation, current optical stimulation strategies lack the capability to react acutely to ongoing cardiac wave dynamics. Here, we developed an all‐optical platform to monitor and control electrical activity in real‐time. The methodology was applied to restore normal electrical activity after atrioventricular block and to manipulate the intraventricular propagation of the electrical wavefront. The closed‐loop approach was also applied to simulate a re‐entrant circuit across the ventricle. The development of this innovative optical methodology provides the first proof‐of‐concept that a real‐time all‐optical stimulation can control cardiac rhythm in normal and abnormal conditions.
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Affiliation(s)
- M Scardigli
- European Laboratory for Non-Linear Spectroscopy, Florence, 50019, Italy.,National Institute of Optics, National Research Council, Florence, 50125, Italy
| | - C Müllenbroich
- European Laboratory for Non-Linear Spectroscopy, Florence, 50019, Italy.,National Institute of Optics, National Research Council, Florence, 50125, Italy
| | - E Margoni
- European Laboratory for Non-Linear Spectroscopy, Florence, 50019, Italy.,Department of Physics, University of Pisa, Pisa, 56127, Italy
| | - S Cannazzaro
- European Laboratory for Non-Linear Spectroscopy, Florence, 50019, Italy.,National Institute of Optics, National Research Council, Florence, 50125, Italy
| | - C Crocini
- European Laboratory for Non-Linear Spectroscopy, Florence, 50019, Italy.,National Institute of Optics, National Research Council, Florence, 50125, Italy
| | - C Ferrantini
- Division of Physiology, Department of Experimental and Clinical Medicine, University of Florence, Florence, 50134, Italy
| | - R Coppini
- Division of Pharmacology, Department 'NeuroFarBa', University of Florence, Florence, 50139, Italy
| | - P Yan
- R. D. Berlin Center for Cell Analysis and Modeling, University of Connecticut School of Medicine, Farmington, CT, 06030, USA
| | - L M Loew
- R. D. Berlin Center for Cell Analysis and Modeling, University of Connecticut School of Medicine, Farmington, CT, 06030, USA
| | - M Campione
- Neuroscience Institute, National Research Council, Padova, 35121, Italy.,Department of Biomedical Sciences, Univercity ot Padua, Padua, 35121, Italy
| | - L Bocchi
- European Laboratory for Non-Linear Spectroscopy, Florence, 50019, Italy.,Department of Information Engineering, University of Florence, Via S. Marta 3, Florence, 50139, Italy
| | - D Giulietti
- National Institute of Optics, National Research Council, Florence, 50125, Italy.,Department of Physics, University of Pisa, Pisa, 56127, Italy
| | - E Cerbai
- Division of Pharmacology, Department 'NeuroFarBa', University of Florence, Florence, 50139, Italy
| | - C Poggesi
- Division of Physiology, Department of Experimental and Clinical Medicine, University of Florence, Florence, 50134, Italy
| | - G Bub
- Department of Physiology, McGill University, Montreal, Quebec, Canada
| | - F S Pavone
- European Laboratory for Non-Linear Spectroscopy, Florence, 50019, Italy.,National Institute of Optics, National Research Council, Florence, 50125, Italy.,Department of Physics and Astronomy, University of Florence, Sesto Fiorentino, 50019, Italy
| | - L Sacconi
- European Laboratory for Non-Linear Spectroscopy, Florence, 50019, Italy.,National Institute of Optics, National Research Council, Florence, 50125, Italy
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15
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Cardiac Optogenetics: 2018. JACC Clin Electrophysiol 2018; 4:155-167. [PMID: 29749932 DOI: 10.1016/j.jacep.2017.12.006] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 12/04/2017] [Accepted: 12/14/2017] [Indexed: 01/28/2023]
Abstract
Cardiac optogenetics is an emergent research area involving the delivery of light-sensitive proteins (opsins) to excitable heart tissue to enable optical modulation of cardiac electrical function. Optogenetic stimulation has many noteworthy advantages over conventional electrical methods, including selective electrophysiological modulation in specifically targeted cell subpopulations, high-resolution spatiotemporal control via patterned illumination, and use of different opsins to elicit inward or outward transmembrane current. This review summarizes developments achieved since the inception of cardiac optogenetics research, which has spanned nearly a decade. The authors first provide an overview of recent methodological advances in opsin engineering, light sensitization of cardiac tissue, strategies for illuminating the heart, and frameworks for simulating optogenetics in realistic computational models of patient hearts. They then review recent cardiac optogenetics applications, including: 1) all-optical, high-throughput, contactless assays for quantification of electrophysiological properties; 2) optogenetic perturbation of cardiac tissue to unveil mechanistic insights on the initiation, perpetuation, and termination of arrhythmia; and 3) disruptive translational innovations such as light-based pacemaking and defibrillation.
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16
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Boyle PM, Murphy MJ, Karathanos TV, Zahid S, Blake RC, Trayanova NA. Termination of re-entrant atrial tachycardia via optogenetic stimulation with optimized spatial targeting: insights from computational models. J Physiol 2017; 596:181-196. [PMID: 29193078 DOI: 10.1113/jp275264] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Accepted: 11/22/2017] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Optogenetics has emerged as a potential alternative to electrotherapy for treating heart rhythm disorders, but its applicability for terminating atrial arrhythmias remains largely unexplored. We used computational models reconstructed from clinical MRI scans of fibrotic patient atria to explore the feasibility of optogenetic termination of atrial tachycardia (AT), comparing two different illumination strategies: distributed vs. targeted. We show that targeted optogenetic stimulation based on automated, non-invasive flow-network analysis of patient-specific re-entry morphology may be a reliable approach for identifying the optimal illumination target in each individual (i.e. the critical AT isthmus). The above-described approach yields very high success rates (up to 100%) and requires dramatically less input power than distributed illumination We conclude that simulations in patient-specific models show that targeted light pulses lasting longer than the AT cycle length can efficiently and reliably terminate AT if the human atria can be successfully light-sensitized via gene delivery of ChR2. ABSTRACT Optogenetics has emerged as a potential alternative to electrotherapy for treating arrhythmia, but feasibility studies have been limited to ventricular defibrillation via epicardial light application. Here, we assess the efficacy of optogenetic atrial tachycardia (AT) termination in human hearts using a strategy that targets for illumination specific regions identified in an automated manner. In three patient-specific models reconstructed from late gadolinium-enhanced MRI scans, we simulated channelrhodopsin-2 (ChR2) expression via gene delivery. In all three models, we attempted to terminate re-entrant AT (induced via rapid pacing) via optogenetic stimulation. We compared two strategies: (1) distributed illumination of the endocardium by multi-optrode grids (number of optrodes, Nopt = 64, 128, 256) and (2) targeted illumination of the critical isthmus, which was identified via analysis of simulated activation patterns using an algorithm based on flow networks. The illuminated area and input power were smaller for the targeted approach (19-57.8 mm2 ; 0.6-1.8 W) compared to the sparsest distributed arrays (Nopt = 64; 124.9 ± 6.3 mm2 ; 3.9 ± 0.2 W). AT termination rates for distributed illumination were low, ranging from <5% for short pulses (1/10 ms long) to ∼20% for longer stimuli (100/1000 ms). When we attempted to terminate the same AT episodes with targeted illumination, outcomes were similar for short pulses (1/10 ms long: 0% success) but improved for longer stimuli (100 ms: 54% success; 1000 ms: 90% success). We conclude that simulations in patient-specific models show that light pulses lasting longer than the AT cycle length can efficiently and reliably terminate AT in atria light-sensitized via gene delivery. We show that targeted optogenetic stimulation based on analysis of AT morphology may be a reliable approach for defibrillation and requires less power than distributed illumination.
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Affiliation(s)
- Patrick M Boyle
- Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Michael J Murphy
- Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Thomas V Karathanos
- Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Sohail Zahid
- Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Robert C Blake
- Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Natalia A Trayanova
- Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD, USA.,Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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17
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Karathanos TV, Bayer JD, Wang D, Boyle PM, Trayanova NA. Opsin spectral sensitivity determines the effectiveness of optogenetic termination of ventricular fibrillation in the human heart: a simulation study. J Physiol 2016; 594:6879-6891. [PMID: 26941055 PMCID: PMC5134403 DOI: 10.1113/jp271739] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 03/01/2016] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Optogenetics-based defibrillation, a theoretical alternative to electrotherapy, involves expression of light-sensitive ion channels in the heart (via gene or cell therapy) and illumination of the cardiac surfaces (via implanted LED arrays) to elicit light-induced activations. We used a biophysically detailed human ventricular model to determine whether such a therapy could terminate fibrillation (VF) and identify which combinations of light-sensitive ion channel properties and illumination configurations would be effective. Defibrillation was successful when a large proportion (> 16.6%) of ventricular tissue was directly stimulated by light that was bright enough to induce an action potential in an uncoupled cell. While illumination with blue light never successfully terminated VF, illumination of red light-sensitive ion channels with dense arrays of implanted red light sources resulted in successful defibrillation. Our results suggest that cardiac expression of red light-sensitive ion channels is necessary for the development of effective optogenetics-based defibrillation therapy using LED arrays. ABSTRACT Optogenetics-based defibrillation has been proposed as a novel and potentially pain-free approach to enable cardiomyocyte-selective defibrillation in humans, but the feasibility of such a therapy remains unknown. This study aimed to (1) assess the feasibility of terminating sustained ventricular fibrillation (VF) via light-induced excitation of opsins expressed throughout the myocardium and (2) identify the ideal (theoretically possible) opsin properties and light source configurations that would maximise therapeutic efficacy. We conducted electrophysiological simulations in an MRI-based human ventricular model with VF induced by rapid pacing; light sensitisation via systemic, cardiac-specific gene transfer of channelrhodopsin-2 (ChR2) was simulated. In addition to the widely used blue light-sensitive ChR2-H134R, we also modelled theoretical ChR2 variants with augmented light sensitivity (ChR2+), red-shifted spectral sensitivity (ChR2-RED) or both (ChR2-RED+). Light sources were modelled as synchronously activating LED arrays (LED radius: 1 mm; optical power: 10 mW mm-2 ; array density: 1.15-4.61 cm-2 ). For each unique optogenetic configuration, defibrillation was attempted with two different optical pulse durations (25 and 500 ms). VF termination was only successful for configurations involving ChR2-RED and ChR2-RED+ (for LED arrays with density ≥ 2.30 cm-2 ), suggesting that opsin spectral sensitivity was the most important determinant of optogenetic defibrillation efficacy. This was due to the deeper penetration of red light in cardiac tissue compared with blue light, which resulted in more widespread light-induced propagating wavefronts. Longer pulse duration and higher LED array density were associated with increased optogenetic defibrillation efficacy. In all cases observed, the defibrillation mechanism was light-induced depolarisation of the excitable gap, which led to block of reentrant wavefronts.
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Affiliation(s)
- Thomas V. Karathanos
- Institute for Computational MedicineDepartment of Biomedical EngineeringJohns Hopkins UniversityBaltimoreMDUSA
| | - Jason D. Bayer
- LIRYC Electrophysiology and Heart Modelling InstituteUniversity of BordeauxBordeauxFrance
| | - Dafang Wang
- Institute for Computational MedicineDepartment of Biomedical EngineeringJohns Hopkins UniversityBaltimoreMDUSA
| | - Patrick M. Boyle
- Institute for Computational MedicineDepartment of Biomedical EngineeringJohns Hopkins UniversityBaltimoreMDUSA
| | - Natalia A. Trayanova
- Institute for Computational MedicineDepartment of Biomedical EngineeringJohns Hopkins UniversityBaltimoreMDUSA
- Department of MedicineJohns Hopkins University School of MedicineBaltimoreMDUSA
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18
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Karathanos TV, Boyle PM, Trayanova NA. Light-based Approaches to Cardiac Arrhythmia Research: From Basic Science to Translational Applications. CLINICAL MEDICINE INSIGHTS-CARDIOLOGY 2016; 10:47-60. [PMID: 27840581 PMCID: PMC5094582 DOI: 10.4137/cmc.s39711] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Revised: 09/27/2016] [Accepted: 10/09/2016] [Indexed: 02/06/2023]
Abstract
Light has long been used to image the heart, but now it can be used to modulate its electrophysiological function. Imaging modalities and techniques have long constituted an indispensable part of arrhythmia research and treatment. Recently, advances in the fields of optogenetics and photodynamic therapy have provided scientists with more effective approaches for probing, studying and potentially devising new treatments for cardiac arrhythmias. This article is a review of research toward the application of these techniques. It contains (a) an overview of advancements in technology and research that have contributed to light-based cardiac applications and (b) a summary of current and potential future applications of light-based control of cardiac cells, including modulation of heart rhythm, manipulation of cardiac action potential morphology, quantitative analysis of arrhythmias, defibrillation and cardiac ablation.
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Affiliation(s)
- Thomas V. Karathanos
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
- Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Patrick M. Boyle
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
- Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Natalia A. Trayanova
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
- Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD, USA
- Department of Medicine, Johns Hopkins University, Baltimore, MD, USA
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19
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Bruegmann T, Boyle PM, Vogt CC, Karathanos TV, Arevalo HJ, Fleischmann BK, Trayanova NA, Sasse P. Optogenetic defibrillation terminates ventricular arrhythmia in mouse hearts and human simulations. J Clin Invest 2016; 126:3894-3904. [PMID: 27617859 DOI: 10.1172/jci88950] [Citation(s) in RCA: 115] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 08/04/2016] [Indexed: 11/17/2022] Open
Abstract
Ventricular arrhythmias are among the most severe complications of heart disease and can result in sudden cardiac death. Patients at risk currently receive implantable defibrillators that deliver electrical shocks to terminate arrhythmias on demand. However, strong electrical shocks can damage the heart and cause severe pain. Therefore, we have tested optogenetic defibrillation using expression of the light-sensitive channel channelrhodopsin-2 (ChR2) in cardiac tissue. Epicardial illumination effectively terminated ventricular arrhythmias in hearts from transgenic mice and from WT mice after adeno-associated virus-based gene transfer of ChR2. We also explored optogenetic defibrillation for human hearts, taking advantage of a recently developed, clinically validated in silico approach for simulating infarct-related ventricular tachycardia (VT). Our analysis revealed that illumination with red light effectively terminates VT in diseased, ChR2-expressing human hearts. Mechanistically, we determined that the observed VT termination is due to ChR2-mediated transmural depolarization of the myocardium, which causes a block of voltage-dependent Na+ channels throughout the myocardial wall and interrupts wavefront propagation into illuminated tissue. Thus, our results demonstrate that optogenetic defibrillation is highly effective in the mouse heart and could potentially be translated into humans to achieve nondamaging and pain-free termination of ventricular arrhythmia.
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20
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Ciaccio EJ. Honored papers 2015. Comput Biol Med 2016. [DOI: 10.1016/j.compbiomed.2016.05.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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21
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Optogenetics-enabled assessment of viral gene and cell therapy for restoration of cardiac excitability. Sci Rep 2015; 5:17350. [PMID: 26621212 PMCID: PMC4664892 DOI: 10.1038/srep17350] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 10/29/2015] [Indexed: 12/27/2022] Open
Abstract
Multiple cardiac pathologies are accompanied by loss of tissue excitability, which leads to a range of heart rhythm disorders (arrhythmias). In addition to electronic device therapy (i.e. implantable pacemakers and cardioverter/defibrillators), biological approaches have recently been explored to restore pacemaking ability and to correct conduction slowing in the heart by delivering excitatory ion channels or ion channel agonists. Using optogenetics as a tool to selectively interrogate only cells transduced to produce an exogenous excitatory ion current, we experimentally and computationally quantify the efficiency of such biological approaches in rescuing cardiac excitability as a function of the mode of application (viral gene delivery or cell delivery) and the geometry of the transduced region (focal or spatially-distributed). We demonstrate that for each configuration (delivery mode and spatial pattern), the optical energy needed to excite can be used to predict therapeutic efficiency of excitability restoration. Taken directly, these results can help guide optogenetic interventions for light-based control of cardiac excitation. More generally, our findings can help optimize gene therapy for restoration of cardiac excitability.
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