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Djemai M, Cupelli M, Boutjdir M, Chahine M. Optical Mapping of Cardiomyocytes in Monolayer Derived from Induced Pluripotent Stem Cells. Cells 2023; 12:2168. [PMID: 37681899 PMCID: PMC10487143 DOI: 10.3390/cells12172168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 08/21/2023] [Accepted: 08/25/2023] [Indexed: 09/09/2023] Open
Abstract
Optical mapping is a powerful imaging technique widely adopted to measure membrane potential changes and intracellular Ca2+ variations in excitable tissues using voltage-sensitive dyes and Ca2+ indicators, respectively. This powerful tool has rapidly become indispensable in the field of cardiac electrophysiology for studying depolarization wave propagation, estimating the conduction velocity of electrical impulses, and measuring Ca2+ dynamics in cardiac cells and tissues. In addition, mapping these electrophysiological parameters is important for understanding cardiac arrhythmia mechanisms. In this review, we delve into the fundamentals of cardiac optical mapping technology and its applications when applied to hiPSC-derived cardiomyocytes and discuss related advantages and challenges. We also provide a detailed description of the processing and analysis of optical mapping data, which is a crucial step in the study of cardiac diseases and arrhythmia mechanisms for extracting and comparing relevant electrophysiological parameters.
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Affiliation(s)
- Mohammed Djemai
- CERVO Brain Research Center, Institut Universitaire en Santé Mentale de Québec, Quebec City, QC G1J 2G3, Canada
| | - Michael Cupelli
- Cardiovascular Research Program, VA New York Harbor Healthcare System, New York, NY 11209, USA
- Department of Medicine, Cell Biology and Pharmacology, State University of New York Downstate Health Sciences University, New York, NY 11203, USA
| | - Mohamed Boutjdir
- Cardiovascular Research Program, VA New York Harbor Healthcare System, New York, NY 11209, USA
- Department of Medicine, Cell Biology and Pharmacology, State University of New York Downstate Health Sciences University, New York, NY 11203, USA
- Department of Medicine, NYU School of Medicine, New York, NY 10016, USA
| | - Mohamed Chahine
- CERVO Brain Research Center, Institut Universitaire en Santé Mentale de Québec, Quebec City, QC G1J 2G3, Canada
- Department of Medicine, Faculty of Medicine, Université Laval, Quebec City, QC G1V 0A6, Canada
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2
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Heinson YW, Han JL, Entcheva E. Portable low-cost macroscopic mapping system for all-optical cardiac electrophysiology. JOURNAL OF BIOMEDICAL OPTICS 2023; 28:016001. [PMID: 36636698 PMCID: PMC9830584 DOI: 10.1117/1.jbo.28.1.016001] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Accepted: 12/19/2022] [Indexed: 05/10/2023]
Abstract
SIGNIFICANCE All-optical cardiac electrophysiology enables the visualization and control of key parameters relevant to the detection of cardiac arrhythmias. Mapping such responses in human induced pluripotent stem-cell-derived cardiomyocytes (hiPSC-CMs) is of great interest for cardiotoxicity and personalized medicine applications. AIM We introduce and validate a very low-cost compact mapping system for macroscopic all-optical electrophysiology in layers of hiPSC-CMs. APPROACH The system uses oblique transillumination, low-cost cameras, light-emitting diodes, and off-the-shelf components (total < $ 15 , 000 ) to capture voltage, calcium, and mechanical waves under electrical or optical stimulation. RESULTS Our results corroborate the equivalency of electrical and optogenetic stimulation of hiPSC-CMs, and V m - [ Ca 2 + ] i similarity in conduction under pacing. Green-excitable optical sensors are combinable with blue optogenetic actuators (chanelrhodopsin2) only under very low green light ( < 0.05 mW / mm 2 ). Measurements in warmer culture medium yield larger spread of action potential duration and higher conduction velocities compared to Tyrode's solution at room temperature. CONCLUSIONS As multiple optical sensors and actuators are combined, our results can help handle the "spectral congestion" and avoid parameter distortion. We illustrate the utility of the system for uncovering the action of cellular uncoupling agents and show extensibility to an epi-illumination mode for future imaging of thicker native or engineered tissues.
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Affiliation(s)
- Yuli W. Heinson
- George Washington University, Department of Biomedical Engineering, Washington, DC, United States
| | - Julie L. Han
- George Washington University, Department of Biomedical Engineering, Washington, DC, United States
| | - Emilia Entcheva
- George Washington University, Department of Biomedical Engineering, Washington, DC, United States
- Address all correspondence to Emilia Entcheva,
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3
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Ripplinger CM, Glukhov AV, Kay MW, Boukens BJ, Chiamvimonvat N, Delisle BP, Fabritz L, Hund TJ, Knollmann BC, Li N, Murray KT, Poelzing S, Quinn TA, Remme CA, Rentschler SL, Rose RA, Posnack NG. Guidelines for assessment of cardiac electrophysiology and arrhythmias in small animals. Am J Physiol Heart Circ Physiol 2022; 323:H1137-H1166. [PMID: 36269644 PMCID: PMC9678409 DOI: 10.1152/ajpheart.00439.2022] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 10/11/2022] [Accepted: 10/17/2022] [Indexed: 01/09/2023]
Abstract
Cardiac arrhythmias are a major cause of morbidity and mortality worldwide. Although recent advances in cell-based models, including human-induced pluripotent stem cell-derived cardiomyocytes (iPSC-CM), are contributing to our understanding of electrophysiology and arrhythmia mechanisms, preclinical animal studies of cardiovascular disease remain a mainstay. Over the past several decades, animal models of cardiovascular disease have advanced our understanding of pathological remodeling, arrhythmia mechanisms, and drug effects and have led to major improvements in pacing and defibrillation therapies. There exist a variety of methodological approaches for the assessment of cardiac electrophysiology and a plethora of parameters may be assessed with each approach. This guidelines article will provide an overview of the strengths and limitations of several common techniques used to assess electrophysiology and arrhythmia mechanisms at the whole animal, whole heart, and tissue level with a focus on small animal models. We also define key electrophysiological parameters that should be assessed, along with their physiological underpinnings, and the best methods with which to assess these parameters.
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Affiliation(s)
- Crystal M Ripplinger
- Department of Pharmacology, University of California Davis School of Medicine, Davis, California
| | - Alexey V Glukhov
- Department of Medicine, Cardiovascular Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin
| | - Matthew W Kay
- Department of Biomedical Engineering, The George Washington University, Washington, District of Columbia
| | - Bastiaan J Boukens
- Department Physiology, University Maastricht, Maastricht University Medical Center, Maastricht, The Netherlands
- Department of Medical Biology, University of Amsterdam, Amsterdam University Medical Center, Amsterdam, The Netherlands
| | - Nipavan Chiamvimonvat
- Department of Pharmacology, University of California Davis School of Medicine, Davis, California
- Department of Internal Medicine, University of California Davis School of Medicine, Davis, California
- Veterans Affairs Northern California Healthcare System, Mather, California
| | - Brian P Delisle
- Department of Physiology, University of Kentucky, Lexington, Kentucky
| | - Larissa Fabritz
- University Center of Cardiovascular Science, University Heart and Vascular Center, University Hospital Hamburg-Eppendorf with DZHK Hamburg/Kiel/Luebeck, Germany
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Thomas J Hund
- Department of Internal Medicine, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio
- Department of Biomedical Engineering, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio
| | - Bjorn C Knollmann
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Na Li
- Department of Medicine, Baylor College of Medicine, Houston, Texas
| | - Katherine T Murray
- Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Steven Poelzing
- Virginia Tech Carilon School of Medicine, Center for Heart and Reparative Medicine Research, Fralin Biomedical Research Institute at Virginia Tech, Roanoke, Virginia
- Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, Virginia
| | - T Alexander Quinn
- Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada
- School of Biomedical Engineering, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Carol Ann Remme
- Department of Experimental Cardiology, Heart Centre, Amsterdam Cardiovascular Sciences, Heart Failure and Arrhythmias Amsterdam UMC Location University of Amsterdam, Amsterdam, The Netherlands
| | - Stacey L Rentschler
- Cardiovascular Division, Department of Medicine, Washington University in Saint Louis, School of Medicine, Saint Louis, Missouri
| | - Robert A Rose
- Department of Cardiac Sciences, Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
- Department of Physiology and Pharmacology, Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Nikki G Posnack
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital, Washington, District of Columbia
- Department of Pediatrics, George Washington University School of Medicine, Washington, District of Columbia
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4
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Lebert J, Ravi N, Kensah G, Christoph J. Real-Time Optical Mapping of Contracting Cardiac Tissues With GPU-Accelerated Numerical Motion Tracking. Front Cardiovasc Med 2022; 9:787627. [PMID: 35686036 PMCID: PMC9172765 DOI: 10.3389/fcvm.2022.787627] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 04/12/2022] [Indexed: 11/15/2022] Open
Abstract
Optical mapping of action potentials or calcium transients in contracting cardiac tissues are challenging because of the severe sensitivity of the measurements to motion. The measurements rely on the accurate numerical tracking and analysis of fluorescence changes emitted by the tissue as it moves, and inaccurate or no tracking can produce motion artifacts and lead to imprecise measurements that can prohibit the analysis of the data. Recently, it was demonstrated that numerical motion-tracking and -stabilization can effectively inhibit motion artifacts, allowing highly detailed simultaneous measurements of electrophysiological phenomena and tissue mechanics. However, the field of electromechanical optical mapping is still young and under development. To date, the technique is only used by a few laboratories, the processing of the video data is time-consuming and performed offline post-acquisition as it is associated with a considerable demand for computing power. In addition, a systematic review of numerical motion tracking algorithms applicable to optical mapping data is lacking. To address these issues, we evaluated 5 open-source numerical motion-tracking algorithms implemented on a graphics processing unit (GPU) and compared their performance when tracking and compensating motion and measuring optical traces in voltage- or calcium-sensitive optical mapping videos of contracting cardiac tissues. Using GPU-accelerated numerical motion tracking, the processing times necessary to analyze optical mapping videos become substantially reduced. We demonstrate that it is possible to track and stabilize motion and create motion-compensated optical maps in real-time with low-resolution (128 x 128 pixels) and high resolution (800 x 800 pixels) optical mapping videos acquired at 500 and 40 fps, respectively. We evaluated the tracking accuracies and motion-stabilization capabilities of the GPU-based algorithms on synthetic optical mapping videos, determined their sensitivity to fluorescence signals and noise, and demonstrate the efficacy of the Farnebäck algorithm with recordings of contracting human cardiac cell cultures and beating hearts from 3 different species (mouse, rabbit, pig) imaged with 4 different high-speed cameras. GPU-accelerated processing provides a substantial increase in processing speed, which could open the path for more widespread use of numerical motion tracking and stabilization algorithms during routine optical mapping studies.
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Affiliation(s)
- Jan Lebert
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, United States
- German Center for Cardiovascular Research (DZHK e.V.), Göttingen, Germany
| | - Namita Ravi
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, United States
- Yale School of Medicine, Yale University, New Haven, CT, United States
| | - George Kensah
- German Center for Cardiovascular Research (DZHK e.V.), Göttingen, Germany
- Department for Cardiothoracic and Vascular Surgery, University Medical Center Göttingen, Göttingen, Germany
| | - Jan Christoph
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, United States
- German Center for Cardiovascular Research (DZHK e.V.), Göttingen, Germany
- *Correspondence: Jan Christoph
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5
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Lebert J, Ravi N, Fenton FH, Christoph J. Rotor Localization and Phase Mapping of Cardiac Excitation Waves Using Deep Neural Networks. Front Physiol 2022; 12:782176. [PMID: 34975536 PMCID: PMC8718715 DOI: 10.3389/fphys.2021.782176] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Accepted: 11/11/2021] [Indexed: 11/15/2022] Open
Abstract
The analysis of electrical impulse phenomena in cardiac muscle tissue is important for the diagnosis of heart rhythm disorders and other cardiac pathophysiology. Cardiac mapping techniques acquire local temporal measurements and combine them to visualize the spread of electrophysiological wave phenomena across the heart surface. However, low spatial resolution, sparse measurement locations, noise and other artifacts make it challenging to accurately visualize spatio-temporal activity. For instance, electro-anatomical catheter mapping is severely limited by the sparsity of the measurements, and optical mapping is prone to noise and motion artifacts. In the past, several approaches have been proposed to create more reliable maps from noisy or sparse mapping data. Here, we demonstrate that deep learning can be used to compute phase maps and detect phase singularities in optical mapping videos of ventricular fibrillation, as well as in very noisy, low-resolution and extremely sparse simulated data of reentrant wave chaos mimicking catheter mapping data. The self-supervised deep learning approach is fundamentally different from classical phase mapping techniques. Rather than encoding a phase signal from time-series data, a deep neural network instead learns to directly associate phase maps and the positions of phase singularities with short spatio-temporal sequences of electrical data. We tested several neural network architectures, based on a convolutional neural network (CNN) with an encoding and decoding structure, to predict phase maps or rotor core positions either directly or indirectly via the prediction of phase maps and a subsequent classical calculation of phase singularities. Predictions can be performed across different data, with models being trained on one species and then successfully applied to another, or being trained solely on simulated data and then applied to experimental data. Neural networks provide a promising alternative to conventional phase mapping and rotor core localization methods. Future uses may include the analysis of optical mapping studies in basic cardiovascular research, as well as the mapping of atrial fibrillation in the clinical setting.
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Affiliation(s)
- Jan Lebert
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, United States
| | - Namita Ravi
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, United States.,Yale School of Medicine, Yale University, New Haven, CT, United States
| | - Flavio H Fenton
- School of Physics, Georgia Institute of Technology, Atlanta, GA, United States
| | - Jan Christoph
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, United States
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6
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Müllenbroich MC, Kelly A, Acker C, Bub G, Bruegmann T, Di Bona A, Entcheva E, Ferrantini C, Kohl P, Lehnart SE, Mongillo M, Parmeggiani C, Richter C, Sasse P, Zaglia T, Sacconi L, Smith GL. Novel Optics-Based Approaches for Cardiac Electrophysiology: A Review. Front Physiol 2021; 12:769586. [PMID: 34867476 PMCID: PMC8637189 DOI: 10.3389/fphys.2021.769586] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 10/18/2021] [Indexed: 12/31/2022] Open
Abstract
Optical techniques for recording and manipulating cellular electrophysiology have advanced rapidly in just a few decades. These developments allow for the analysis of cardiac cellular dynamics at multiple scales while largely overcoming the drawbacks associated with the use of electrodes. The recent advent of optogenetics opens up new possibilities for regional and tissue-level electrophysiological control and hold promise for future novel clinical applications. This article, which emerged from the international NOTICE workshop in 2018, reviews the state-of-the-art optical techniques used for cardiac electrophysiological research and the underlying biophysics. The design and performance of optical reporters and optogenetic actuators are reviewed along with limitations of current probes. The physics of light interaction with cardiac tissue is detailed and associated challenges with the use of optical sensors and actuators are presented. Case studies include the use of fluorescence recovery after photobleaching and super-resolution microscopy to explore the micro-structure of cardiac cells and a review of two photon and light sheet technologies applied to cardiac tissue. The emergence of cardiac optogenetics is reviewed and the current work exploring the potential clinical use of optogenetics is also described. Approaches which combine optogenetic manipulation and optical voltage measurement are discussed, in terms of platforms that allow real-time manipulation of whole heart electrophysiology in open and closed-loop systems to study optimal ways to terminate spiral arrhythmias. The design and operation of optics-based approaches that allow high-throughput cardiac electrophysiological assays is presented. Finally, emerging techniques of photo-acoustic imaging and stress sensors are described along with strategies for future development and establishment of these techniques in mainstream electrophysiological research.
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Affiliation(s)
| | - Allen Kelly
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Corey Acker
- Center for Cell Analysis and Modeling, UConn Health, Farmington, CT, United States
| | - Gil Bub
- Department of Physiology, McGill University, Montréal, QC, Canada
| | - Tobias Bruegmann
- Institute for Cardiovascular Physiology, University Medical Center Goettingen, Goettingen, Germany
| | - Anna Di Bona
- Department of Cardiac, Thoracic, Vascular Sciences and Public Health, University of Padova, Padova, Italy
| | - Emilia Entcheva
- Department of Biomedical Engineering, The George Washington University, Washington, DC, United States
| | | | - Peter Kohl
- Institute for Experimental Cardiovascular Medicine, University Heart Center and Medical Faculty, University of Freiburg, Freiburg, Germany
| | - Stephan E. Lehnart
- Heart Research Center Göttingen, University Medical Center Göttingen, Göttingen, Germany
- Department of Cardiology and Pneumology, Georg-August University Göttingen, Göttingen, Germany
- Cluster of Excellence “Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells” (MBExC), University of Göttingen, Göttingen, Germany
| | - Marco Mongillo
- Department of Biomedical Sciences, University of Padova, Padova, Italy
- Veneto Institute of Molecular Medicine, Padova, Italy
| | | | - Claudia Richter
- German Primate Center - Leibniz Institute for Primate Research, Göttingen, Germany
| | - Philipp Sasse
- Institute of Physiology I, Medical Faculty, University of Bonn, Bonn, Germany
| | - Tania Zaglia
- Department of Biomedical Sciences, University of Padova, Padova, Italy
- Veneto Institute of Molecular Medicine, Padova, Italy
| | - Leonardo Sacconi
- European Laboratory for Nonlinear Spectroscopy, Sesto Fiorentino, Italy
- Institute for Experimental Cardiovascular Medicine, University Heart Center and Medical Faculty, University of Freiburg, Freiburg, Germany
- National Institute of Optics, National Research Council, Florence, Italy
| | - Godfrey L. Smith
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom
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7
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Stoyek MR, Hortells L, Quinn TA. From Mice to Mainframes: Experimental Models for Investigation of the Intracardiac Nervous System. J Cardiovasc Dev Dis 2021; 8:149. [PMID: 34821702 PMCID: PMC8620975 DOI: 10.3390/jcdd8110149] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 10/28/2021] [Accepted: 11/01/2021] [Indexed: 01/17/2023] Open
Abstract
The intracardiac nervous system (IcNS), sometimes referred to as the "little brain" of the heart, is involved in modulating many aspects of cardiac physiology. In recent years our fundamental understanding of autonomic control of the heart has drastically improved, and the IcNS is increasingly being viewed as a therapeutic target in cardiovascular disease. However, investigations of the physiology and specific roles of intracardiac neurons within the neural circuitry mediating cardiac control has been hampered by an incomplete knowledge of the anatomical organisation of the IcNS. A more thorough understanding of the IcNS is hoped to promote the development of new, highly targeted therapies to modulate IcNS activity in cardiovascular disease. In this paper, we first provide an overview of IcNS anatomy and function derived from experiments in mammals. We then provide descriptions of alternate experimental models for investigation of the IcNS, focusing on a non-mammalian model (zebrafish), neuron-cardiomyocyte co-cultures, and computational models to demonstrate how the similarity of the relevant processes in each model can help to further our understanding of the IcNS in health and disease.
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Affiliation(s)
- Matthew R. Stoyek
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS 15000, Canada;
| | - Luis Hortells
- Institute for Experimental Cardiovascular Medicine, University Heart Centre Freiburg–Bad Krozingen, 79110 Freiburg, Germany;
- Faculty of Medicine, University of Freiburg, 79110 Freiburg, Germany
| | - T. Alexander Quinn
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS 15000, Canada;
- School of Biomedical Engineering, Dalhousie University, Halifax, NS 15000, Canada
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8
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Del-Canto I, Gómez-Cid L, Hernández-Romero I, Guillem MS, Fernández-Santos ME, Atienza F, Such L, Fernández-Avilés F, Chorro FJ, Climent AM. Ranolazine-Mediated Attenuation of Mechanoelectric Feedback in Atrial Myocyte Monolayers. Front Physiol 2020; 11:922. [PMID: 32848863 PMCID: PMC7417656 DOI: 10.3389/fphys.2020.00922] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 07/09/2020] [Indexed: 12/20/2022] Open
Abstract
Background Mechanical stretch increases Na+ inflow into myocytes, related to mechanisms including stretch-activated channels or Na+/H+ exchanger activation, involving Ca2+ increase that leads to changes in electrophysiological properties favoring arrhythmia induction. Ranolazine is an antianginal drug with confirmed beneficial effects against cardiac arrhythmias associated with the augmentation of INaL current and Ca2+ overload. Objective This study investigates the effects of mechanical stretch on activation patterns in atrial cell monolayers and its pharmacological response to ranolazine. Methods Confluent HL-1 cells were cultured in silicone membrane plates and were stretched to 110% of original length. The characteristics of in vitro fibrillation (dominant frequency, regularity index, density of phase singularities, rotor meandering, and rotor curvature) were analyzed using optical mapping in order to study the mechanoelectric response to stretch under control conditions and ranolazine action. Results HL-1 cell stretch increased fibrillatory dominant frequency (3.65 ± 0.69 vs. 4.35 ± 0.74 Hz, p < 0.01) and activation complexity (1.97 ± 0.45 vs. 2.66 ± 0.58 PS/cm2, p < 0.01) under control conditions. These effects were related to stretch-induced changes affecting the reentrant patterns, comprising a decrease in rotor meandering (0.72 ± 0.12 vs. 0.62 ± 0.12 cm/s, p < 0.001) and an increase in wavefront curvature (4.90 ± 0.42 vs. 5.68 ± 0.40 rad/cm, p < 0.001). Ranolazine reduced stretch-induced effects, attenuating the activation rate increment (12.8% vs. 19.7%, p < 0.01) and maintaining activation complexity—both parameters being lower during stretch than under control conditions. Moreover, under baseline conditions, ranolazine slowed and regularized the activation patterns (3.04 ± 0.61 vs. 3.65 ± 0.69 Hz, p < 0.01). Conclusion Ranolazine attenuates the modifications of activation patterns induced by mechanical stretch in atrial myocyte monolayers.
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Affiliation(s)
- Irene Del-Canto
- INCLIVA Health Research Institute, Centro de Investigación Biomédica en Red en Enfermedades Cardiovasculares, Valencia, Spain.,Department of Electronic Engineering, Universitat Politècnica de València, Valencia, Spain
| | - Lidia Gómez-Cid
- Department of Cardiology, Hospital General Universitario Gregorio Marañón, Instituto de Investigación Sanitaria Gregorio Marañón, Centro de Investigación Biomédica en Red en Enfermedades Cardiovasculares, Madrid, Spain
| | | | - María S Guillem
- ITACA Institute, Universitat Politècnica de València, Valencia, Spain
| | - María Eugenia Fernández-Santos
- Department of Cardiology, Hospital General Universitario Gregorio Marañón, Instituto de Investigación Sanitaria Gregorio Marañón, Centro de Investigación Biomédica en Red en Enfermedades Cardiovasculares, Madrid, Spain
| | - Felipe Atienza
- Department of Cardiology, Hospital General Universitario Gregorio Marañón, Instituto de Investigación Sanitaria Gregorio Marañón, Centro de Investigación Biomédica en Red en Enfermedades Cardiovasculares, Madrid, Spain
| | - Luis Such
- INCLIVA Health Research Institute, Centro de Investigación Biomédica en Red en Enfermedades Cardiovasculares, Valencia, Spain.,Department of Physiology, Universitat de València Estudi General, Valencia, Spain
| | - Francisco Fernández-Avilés
- Department of Cardiology, Hospital General Universitario Gregorio Marañón, Instituto de Investigación Sanitaria Gregorio Marañón, Centro de Investigación Biomédica en Red en Enfermedades Cardiovasculares, Madrid, Spain
| | - Francisco J Chorro
- INCLIVA Health Research Institute, Centro de Investigación Biomédica en Red en Enfermedades Cardiovasculares, Valencia, Spain.,Department of Cardiology, Hospital Clínico Universitario de Valencia, INCLIVA, Valencia, Spain
| | - Andreu M Climent
- Department of Cardiology, Hospital General Universitario Gregorio Marañón, Instituto de Investigación Sanitaria Gregorio Marañón, Centro de Investigación Biomédica en Red en Enfermedades Cardiovasculares, Madrid, Spain.,ITACA Institute, Universitat Politècnica de València, Valencia, Spain
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9
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Burton RAB, Tomek J, Ambrosi CM, Larsen HE, Sharkey AR, Capel RA, Corbett AD, Bilton S, Klimas A, Stephens G, Cremer M, Bose SJ, Li D, Gallone G, Herring N, Mann EO, Kumar A, Kramer H, Entcheva E, Paterson DJ, Bub G. Optical Interrogation of Sympathetic Neuronal Effects on Macroscopic Cardiomyocyte Network Dynamics. iScience 2020; 23:101334. [PMID: 32674058 PMCID: PMC7363704 DOI: 10.1016/j.isci.2020.101334] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 05/12/2020] [Accepted: 06/26/2020] [Indexed: 12/21/2022] Open
Abstract
Cardiac stimulation via sympathetic neurons can potentially trigger arrhythmias. We present approaches to study neuron-cardiomyocyte interactions involving optogenetic selective probing and all-optical electrophysiology to measure activity in an automated fashion. Here we demonstrate the utility of optical interrogation of sympathetic neurons and their effects on macroscopic cardiomyocyte network dynamics to address research targets such as the effects of adrenergic stimulation via the release of neurotransmitters, the effect of neuronal numbers on cardiac behavior, and the applicability of optogenetics in mechanistic in vitro studies. As arrhythmias are emergent behaviors that involve the coordinated activity of millions of cells, we image at macroscopic scales to capture complex dynamics. We show that neurons can both decrease and increase wave stability and re-entrant activity in culture depending on their induced activity-a finding that may help us understand the often conflicting results seen in experimental and clinical studies.
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Affiliation(s)
- Rebecca-Ann B Burton
- University of Oxford, Department of Pharmacology, Mansfield Road, Oxford OX1 3QT, UK; University of Oxford, Department of Physiology, Anatomy and Genetics, British Heart Foundation Centre of Research Excellence, Parks Road, Oxford OX1 3PT, UK.
| | - Jakub Tomek
- University of Oxford, Department of Physiology, Anatomy and Genetics, British Heart Foundation Centre of Research Excellence, Parks Road, Oxford OX1 3PT, UK
| | - Christina M Ambrosi
- The George Washington University, Department of Biomedical Engineering, Washington, DC 20052, USA
| | - Hege E Larsen
- University of Oxford, Department of Physiology, Anatomy and Genetics, British Heart Foundation Centre of Research Excellence, Parks Road, Oxford OX1 3PT, UK
| | - Amy R Sharkey
- University of Oxford, Department of Physiology, Anatomy and Genetics, British Heart Foundation Centre of Research Excellence, Parks Road, Oxford OX1 3PT, UK
| | - Rebecca A Capel
- University of Oxford, Department of Pharmacology, Mansfield Road, Oxford OX1 3QT, UK
| | | | - Samuel Bilton
- University of Oxford, Department of Physiology, Anatomy and Genetics, British Heart Foundation Centre of Research Excellence, Parks Road, Oxford OX1 3PT, UK
| | - Aleksandra Klimas
- The George Washington University, Department of Biomedical Engineering, Washington, DC 20052, USA
| | - Guy Stephens
- University of Oxford, Department of Physiology, Anatomy and Genetics, British Heart Foundation Centre of Research Excellence, Parks Road, Oxford OX1 3PT, UK
| | - Maegan Cremer
- University of Oxford, Department of Pharmacology, Mansfield Road, Oxford OX1 3QT, UK
| | - Samuel J Bose
- University of Oxford, Department of Pharmacology, Mansfield Road, Oxford OX1 3QT, UK
| | - Dan Li
- University of Oxford, Department of Physiology, Anatomy and Genetics, British Heart Foundation Centre of Research Excellence, Parks Road, Oxford OX1 3PT, UK
| | - Giuseppe Gallone
- University of Oxford, Department of Physiology, Anatomy and Genetics, British Heart Foundation Centre of Research Excellence, Parks Road, Oxford OX1 3PT, UK; Department of Computational Molecular Biology, Max Planck Institute for Molecular Genetics, Ihnestraße 63-73, 14195 Berlin, Germany
| | - Neil Herring
- University of Oxford, Department of Physiology, Anatomy and Genetics, British Heart Foundation Centre of Research Excellence, Parks Road, Oxford OX1 3PT, UK
| | - Edward O Mann
- University of Oxford, Department of Physiology, Anatomy and Genetics, British Heart Foundation Centre of Research Excellence, Parks Road, Oxford OX1 3PT, UK
| | - Abhinav Kumar
- University of Oxford, Department of Biochemistry, Glycobiology Institute, Oxford, UK
| | - Holger Kramer
- University of Oxford, Department of Physiology, Anatomy and Genetics, British Heart Foundation Centre of Research Excellence, Parks Road, Oxford OX1 3PT, UK
| | - Emilia Entcheva
- The George Washington University, Department of Biomedical Engineering, Washington, DC 20052, USA
| | - David J Paterson
- University of Oxford, Department of Physiology, Anatomy and Genetics, British Heart Foundation Centre of Research Excellence, Parks Road, Oxford OX1 3PT, UK
| | - Gil Bub
- University of Oxford, Department of Physiology, Anatomy and Genetics, British Heart Foundation Centre of Research Excellence, Parks Road, Oxford OX1 3PT, UK; McGill University, Department of Physiology, McIntyre Medical Sciences Building, Room 1128, 3655 Promenade Sir William Osler, Montréal, QC H3G 1Y6, Canada.
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10
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Morrissette-McAlmon J, Ginn B, Somers S, Fukunishi T, Thanitcul C, Rindone A, Hibino N, Tung L, Mao HQ, Grayson W. Biomimetic Model of Contractile Cardiac Tissue with Endothelial Networks Stabilized by Adipose-Derived Stromal/Stem Cells. Sci Rep 2020; 10:8387. [PMID: 32433563 PMCID: PMC7239907 DOI: 10.1038/s41598-020-65064-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Accepted: 04/23/2020] [Indexed: 11/15/2022] Open
Abstract
Cardiac tissue engineering strategies have the potential to regenerate functional myocardium following myocardial infarction. In this study, we utilized novel electrospun fibrin microfiber sheets of different stiffnesses (50.0 ± 11.2 kPa and 90.0 ± 16.4 kPa) to engineer biomimetic models of vascularized cardiac tissues. We characterized tissue assembly, electrophysiology, and contractility of neonatal rat ventricular cardiomyocytes (NRVCMs) cultured on these sheets. NRVCMs cultured on the softer substrates displayed higher conduction velocities (CVs) and improved electrophysiological properties. Human umbilical vein endothelial cells (HUVECs) formed dense networks on the sheets when co-cultured with human adipose-derived stem/stromal cells (hASCs). To achieve vascularized cardiac tissues, we tested various tri-culture protocols of NRVCM:hASC:HUVEC and found that a ratio of 1,500,000:37,500:150,000 cells/cm2 enabled the formation of robust endothelial networks while retaining statistically identical electrophysiological characteristics to NRVCM-only cultures. Tri-cultures at this ratio on 90 kPa substrates exhibited average CVs of 14 ± 0.6 cm/s, Action Potential Duration (APD)80 and APD30 of 152 ± 11 ms and 71 ± 6 ms, respectively, and maximum capture rate (MCR) of 3.9 ± 0.7 Hz. These data indicate the significant potential of generating densely packed endothelial networks together with electrically integrated cardiac cells in vitro as a physiologic 3D cardiac model.
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Affiliation(s)
- Justin Morrissette-McAlmon
- Translational Tissue Engineering Center, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Brian Ginn
- Translational Tissue Engineering Center, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Material Sciences & Engineering, Johns Hopkins University, School of Engineering, Baltimore, MD, USA
| | - Sarah Somers
- Translational Tissue Engineering Center, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Takuma Fukunishi
- Department of Surgery & Cardiac Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Chanon Thanitcul
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Alexandra Rindone
- Translational Tissue Engineering Center, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Narutoshi Hibino
- Department of Surgery & Cardiac Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Leslie Tung
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Hai-Quan Mao
- Translational Tissue Engineering Center, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Material Sciences & Engineering, Johns Hopkins University, School of Engineering, Baltimore, MD, USA
- Institute for NanoBioTechnology (INBT), Johns Hopkins University School of Engineering, Baltimore, MD, USA
| | - Warren Grayson
- Translational Tissue Engineering Center, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
- Department of Material Sciences & Engineering, Johns Hopkins University, School of Engineering, Baltimore, MD, USA.
- Institute for NanoBioTechnology (INBT), Johns Hopkins University School of Engineering, Baltimore, MD, USA.
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11
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Shroff SN, Das SL, Tseng HA, Noueihed J, Fernandez F, White JA, Chen CS, Han X. Voltage Imaging of Cardiac Cells and Tissue Using the Genetically Encoded Voltage Sensor Archon1. iScience 2020; 23:100974. [PMID: 32299055 PMCID: PMC7160579 DOI: 10.1016/j.isci.2020.100974] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2019] [Revised: 02/21/2020] [Accepted: 03/05/2020] [Indexed: 01/19/2023] Open
Abstract
Precise measurement of action potentials (APs) is needed to observe electrical activity and cellular communication within cardiac tissue. Voltage-sensitive dyes (VSDs) are traditionally used to measure cardiac APs; however, they require acute chemical addition that prevents chronic imaging. Genetically encoded voltage indicators (GEVIs) enable long-term studies of APs without the need of chemical additions, but current GEVIs used in cardiac tissue exhibit poor kinetics and/or low signal to noise (SNR). Here, we demonstrate the use of Archon1, a recently developed GEVI, in hiPSC-derived cardiomyocytes (CMs). When expressed in CMs, Archon1 demonstrated fast kinetics comparable with patch-clamp electrophysiology and high SNR significantly greater than the VSD Di-8-ANEPPS. Additionally, Archon1 enabled monitoring of APs across multiple cells simultaneously in 3D cardiac tissues. These results highlight Archon1's capability to investigate the electrical activity of CMs in a variety of applications and its potential to probe functionally complex in vitro models, as well as in vivo systems.
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Affiliation(s)
- Sanaya N Shroff
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA
| | - Shoshana L Das
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA; Harvard-MIT Program in Health Sciences and Technology, Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA 02115, USA
| | - Hua-An Tseng
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA
| | - Jad Noueihed
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA
| | - Fernando Fernandez
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA
| | - John A White
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA
| | - Christopher S Chen
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA; Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA 02115, USA.
| | - Xue Han
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA.
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12
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van Gorp PRR, Trines SA, Pijnappels DA, de Vries AAF. Multicellular In vitro Models of Cardiac Arrhythmias: Focus on Atrial Fibrillation. Front Cardiovasc Med 2020; 7:43. [PMID: 32296716 PMCID: PMC7138102 DOI: 10.3389/fcvm.2020.00043] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 03/06/2020] [Indexed: 12/13/2022] Open
Abstract
Atrial fibrillation (AF) is the most common cardiac arrhythmia in clinical practice with a large socioeconomic impact due to its associated morbidity, mortality, reduction in quality of life and health care costs. Currently, antiarrhythmic drug therapy is the first line of treatment for most symptomatic AF patients, despite its limited efficacy, the risk of inducing potentially life-threating ventricular tachyarrhythmias as well as other side effects. Alternative, in-hospital treatment modalities consisting of electrical cardioversion and invasive catheter ablation improve patients' symptoms, but often have to be repeated and are still associated with serious complications and only suitable for specific subgroups of AF patients. The development and progression of AF generally results from the interplay of multiple disease pathways and is accompanied by structural and functional (e.g., electrical) tissue remodeling. Rational development of novel treatment modalities for AF, with its many different etiologies, requires a comprehensive insight into the complex pathophysiological mechanisms. Monolayers of atrial cells represent a simplified surrogate of atrial tissue well-suited to investigate atrial arrhythmia mechanisms, since they can easily be used in a standardized, systematic and controllable manner to study the role of specific pathways and processes in the genesis, perpetuation and termination of atrial arrhythmias. In this review, we provide an overview of the currently available two- and three-dimensional multicellular in vitro systems for investigating the initiation, maintenance and termination of atrial arrhythmias and AF. This encompasses cultures of primary (animal-derived) atrial cardiomyocytes (CMs), pluripotent stem cell-derived atrial-like CMs and (conditionally) immortalized atrial CMs. The strengths and weaknesses of each of these model systems for studying atrial arrhythmias will be discussed as well as their implications for future studies.
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Affiliation(s)
| | | | | | - Antoine A. F. de Vries
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center, Leiden, Netherlands
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13
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Jaimes R, McCullough D, Siegel B, Swift L, Hiebert J, Mclnerney D, Posnack NG. Lights, camera, path splitter: a new approach for truly simultaneous dual optical mapping of the heart with a single camera. BMC Biomed Eng 2019; 1. [PMID: 31768502 PMCID: PMC6876868 DOI: 10.1186/s42490-019-0024-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Background Optical mapping of transmembrane voltage and intracellular calcium is a powerful tool for investigating cardiac physiology and pathophysiology. However, simultaneous dual mapping of two fluorescent probes remains technically challenging. We introduce a novel, easy-to-use approach that requires a path splitter, single camera and excitation light to simultaneously acquire voltage and calcium signals from whole heart preparations, which can be applied to other physiological models – including neurons and isolated cardiomyocytes. Results Complementary probes were selected that could be excited with a single wavelength light source. Langendorff-perfused hearts (rat, swine) were stained and imaged using a sCMOS camera outfitted with an optical path splitter to simultaneously acquire two emission fields at high spatial and temporal resolution. Voltage (RH237) and calcium (Rhod2) signals were acquired concurrently on a single sensor, resulting in two 384 × 256 images at 814 frames per second. At this frame rate, the signal-to-noise ratio was 47 (RH237) and 85 (Rhod2). Imaging experiments were performed on small rodent hearts, as well as larger pig hearts with sufficient optical signals. In separate experiments, each dye was used independently to assess crosstalk and demonstrate signal specificity. Additionally, the effect of ryanodine on myocardial calcium transients was validated – with no measurable effect on the amplitude of optical action potentials. To demonstrate spatial resolution, ventricular tachycardia was induced –resulting in the novel finding that spatially discordant calcium alternans can be present in different regions of the heart, even when electrical alternans remain concordant. The described system excels in providing a wide field of view and high spatiotemporal resolution for a variety of cardiac preparations. Conclusions We report the first multiparametric mapping system that simultaneously acquires calcium and voltage signals from cardiac preparations, using a path splitter, single camera and excitation light. This approach eliminates the need for multiple cameras, excitation light patterning or frame interleaving. These features can aid in the adoption of dual mapping technology by the broader cardiovascular research community, and decrease the barrier of entry into panoramic heart imaging, as it reduces the number of required cameras. Electronic supplementary material The online version of this article (10.1186/s42490-019-0024-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Rafael Jaimes
- Sheikh Zayed Institute for Pediatric and Surgical Innovation: Children's National Health System, 6th floor, M7708, 111 Michigan Avenue NW, Washington, DC 20010, USA.,Children's National Heart Institute: Children's National Health System, 111 Michigan Avenue NW, Washington, DC 20010, USA
| | - Damon McCullough
- Sheikh Zayed Institute for Pediatric and Surgical Innovation: Children's National Health System, 6th floor, M7708, 111 Michigan Avenue NW, Washington, DC 20010, USA
| | - Bryan Siegel
- Children's National Heart Institute: Children's National Health System, 111 Michigan Avenue NW, Washington, DC 20010, USA
| | - Luther Swift
- Sheikh Zayed Institute for Pediatric and Surgical Innovation: Children's National Health System, 6th floor, M7708, 111 Michigan Avenue NW, Washington, DC 20010, USA.,Children's National Heart Institute: Children's National Health System, 111 Michigan Avenue NW, Washington, DC 20010, USA
| | - James Hiebert
- Sheikh Zayed Institute for Pediatric and Surgical Innovation: Children's National Health System, 6th floor, M7708, 111 Michigan Avenue NW, Washington, DC 20010, USA
| | - Daniel Mclnerney
- Sheikh Zayed Institute for Pediatric and Surgical Innovation: Children's National Health System, 6th floor, M7708, 111 Michigan Avenue NW, Washington, DC 20010, USA
| | - Nikki Gillum Posnack
- Sheikh Zayed Institute for Pediatric and Surgical Innovation: Children's National Health System, 6th floor, M7708, 111 Michigan Avenue NW, Washington, DC 20010, USA.,Children's National Heart Institute: Children's National Health System, 111 Michigan Avenue NW, Washington, DC 20010, USA.,Department of Pediatrics, Department of Pharmacology & Physiology, School of Medicine and Health Sciences: George Washington University, 2300 I Street NW, Washington, DC 20037, USA
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14
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Pfeiffer-Kaushik ER, Smith GL, Cai B, Dempsey GT, Hortigon-Vinagre MP, Zamora V, Feng S, Ingermanson R, Zhu R, Hariharan V, Nguyen C, Pierson J, Gintant GA, Tung L. Electrophysiological characterization of drug response in hSC-derived cardiomyocytes using voltage-sensitive optical platforms. J Pharmacol Toxicol Methods 2019; 99:106612. [PMID: 31319140 DOI: 10.1016/j.vascn.2019.106612] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2019] [Revised: 06/30/2019] [Accepted: 07/10/2019] [Indexed: 01/07/2023]
Abstract
INTRODUCTION Voltage-sensitive optical (VSO) sensors offer a minimally invasive method to study the time course of repolarization of the cardiac action potential (AP). This Comprehensive in vitro Proarrhythmia Assay (CiPA) cross-platform study investigates protocol design and measurement variability of VSO sensors for preclinical cardiac electrophysiology assays. METHODS Three commercial and one academic laboratory completed a limited study of the effects of 8 blinded compounds on the electrophysiology of 2 commercial lines of human induced pluripotent stem-cell derived cardiomyocytes (hSC-CMs). Acquisition technologies included CMOS camera and photometry; fluorescent voltage sensors included di-4-ANEPPS, FluoVolt and genetically encoded QuasAr2. The experimental protocol was standardized with respect to cell lines, plating and maintenance media, blinded compounds, and action potential parameters measured. Serum-free media was used to study the action of drugs, but the exact composition and the protocols for cell preparation and drug additions varied among sites. RESULTS Baseline AP waveforms differed across platforms and between cell types. Despite these differences, the relative responses to four selective ion channel blockers (E-4031, nifedipine, mexiletine, and JNJ 303 blocking IKr, ICaL, INa, and IKs, respectively) were similar across all platforms and cell lines although the absolute changes differed. Similarly, four mixed ion channel blockers (flecainide, moxifloxacin, quinidine, and ranolazine) had comparable effects in all platforms. Differences in repolarisation time course and response to drugs could be attributed to cell type and experimental method differences such as composition of the assay media, stimulated versus spontaneous activity, and single versus cumulative compound addition. DISCUSSION In conclusion, VSOs represent a powerful and appropriate method to assess the electrophysiological effects of drugs on iPSC-CMs for the evaluation of proarrhythmic risk. Protocol considerations and recommendations are provided toward standardizing conditions to reduce variability of baseline AP waveform characteristics and drug responses.
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Affiliation(s)
| | - Godfrey L Smith
- Clyde Biosciences Ltd, BioCity Scotland, Bo'Ness Road, Newhouse, Lanarkshire, Scotland ML1 5UH, United Kingdom; Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary and Life Science, University of Glasgow, 126 University Place, Glasgow G12 8TA, United Kingdom
| | - Beibei Cai
- Vala Sciences Inc., 6370 Nancy Ridge Drive, Suite 106, San Diego, CA 92121, USA
| | - Graham T Dempsey
- Q-State Biosciences Inc., 179 Sidney Street, Cambridge, MA 02139, USA
| | - Maria P Hortigon-Vinagre
- Clyde Biosciences Ltd, BioCity Scotland, Bo'Ness Road, Newhouse, Lanarkshire, Scotland ML1 5UH, United Kingdom; Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary and Life Science, University of Glasgow, 126 University Place, Glasgow G12 8TA, United Kingdom
| | - Victor Zamora
- Clyde Biosciences Ltd, BioCity Scotland, Bo'Ness Road, Newhouse, Lanarkshire, Scotland ML1 5UH, United Kingdom; Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary and Life Science, University of Glasgow, 126 University Place, Glasgow G12 8TA, United Kingdom
| | - Shuyun Feng
- Vala Sciences Inc., 6370 Nancy Ridge Drive, Suite 106, San Diego, CA 92121, USA
| | - Randall Ingermanson
- Vala Sciences Inc., 6370 Nancy Ridge Drive, Suite 106, San Diego, CA 92121, USA
| | - Renjun Zhu
- Department of Biomedical Engineering, The Johns Hopkins University, 720 Rutland Ave., Baltimore, MD 21205, USA
| | - Venkatesh Hariharan
- Department of Biomedical Engineering, The Johns Hopkins University, 720 Rutland Ave., Baltimore, MD 21205, USA
| | - Cuong Nguyen
- Q-State Biosciences Inc., 179 Sidney Street, Cambridge, MA 02139, USA
| | - Jennifer Pierson
- Health and Environmental Sciences Institute, Washington, D.C. 20009, USA.
| | - Gary A Gintant
- AbbVie, 1 North Waukegan Road, Department ZR-13, Building AP-9A, North Chicago, IL 60064-6119, USA
| | - Leslie Tung
- Department of Biomedical Engineering, The Johns Hopkins University, 720 Rutland Ave., Baltimore, MD 21205, USA
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15
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Multimodal on-axis platform for all-optical electrophysiology with near-infrared probes in human stem-cell-derived cardiomyocytes. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2019; 154:62-70. [PMID: 30850184 DOI: 10.1016/j.pbiomolbio.2019.02.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 02/04/2019] [Accepted: 02/11/2019] [Indexed: 12/27/2022]
Abstract
Combined optogenetic stimulation and optical imaging permit scalable, contact-free high-throughput probing of cellular electrophysiology and optimization of stem-cell derived excitable cells, such as neurons and muscle cells. We report a new "on-axis" configuration (combined single optical path for stimulation and for multiparameter imaging) of OptoDyCE, our all-optical platform for studying human induced pluripotent stem-cell-derived cardiomyocytes (hiPSC-CMs) and other cell types, optically driven by Channelrhodopsin2 (ChR2). This solid-state system integrates optogenetic stimulation with temporally-multiplexed simultaneous recording of membrane voltage (Vm) and intracellular calcium ([Ca2+]i) dynamics using a single photodetector. We demonstrate the capacity for combining multiple spectrally-compatible actuators and sensors, including newer high-performance near-infrared (NIR) voltage probes BeRST1 and Di-4-ANBDQBS, to record complex spatiotemporal responses of hiPSC-CMs to drugs in a high-throughput manner.
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16
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Dynamics of spatiotemporal line defects and chaos control in complex excitable systems. Sci Rep 2017; 7:7757. [PMID: 28798384 PMCID: PMC5552747 DOI: 10.1038/s41598-017-08011-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 06/30/2017] [Indexed: 12/01/2022] Open
Abstract
Spatiotemporal pattern formation governs dynamics and functions in various biological systems. In the heart, excitable waves can form complex oscillatory and chaotic patterns even at an abnormally higher frequency than normal heart beats, which increase the risk of fatal heart conditions by inhibiting normal blood circulation. Previous studies suggested that line defects (nodal lines) play a critical role in stabilizing those undesirable patterns. However, it remains unknown if the line defects are static or dynamically changing structures in heart tissue. Through in vitro experiments of heart tissue observation, we reveal the spatiotemporal dynamics of line defects in rotating spiral waves. We combined a novel signaling over-sampling technique with a multi-dimensional Fourier analysis, showing that line defects can translate, merge, collapse and form stable singularities with even and odd parity while maintaining a stable oscillation of the spiral wave in the tissue. These findings provide insights into a broad class of complex periodic systems, with particular impact to the control and understanding of heart diseases.
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17
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Ccoffinn: Automated Wave Tracking in Cultured Cardiac Monolayers. Biophys J 2017; 111:1595-1599. [PMID: 27760347 DOI: 10.1016/j.bpj.2016.08.049] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 08/19/2016] [Accepted: 08/26/2016] [Indexed: 11/23/2022] Open
Abstract
Cardiac arrhythmias are one of the most frequent causes of death worldwide. A popular biological model used to study arrhythmogenesis is the cultured cardiac cell monolayer, which provides a good trade-off between physiological relevance and experimental access. Excitation wave patterns are imaged using high-bandwidth detectors, producing large data sets that are typically analyzed manually. To make such analysis less time consuming and less subjective, we have designed and implemented a toolkit for segmentation and tracking of cardiac waves in optical mapping recordings. The toolkit is optimized for high-resolution detectors to accommodate the growing availability of inexpensive high-resolution detectors for life science imaging applications (e.g., scientific CMOS cameras). The software extracts key features of propagating waves, such as wavefront speed and entropy. The methods have been validated using synthetic data, and real-world examples are provided, showing a difference in conduction velocity between two different types of cardiac cell cultures.
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18
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Dempsey GT, Chaudhary KW, Atwater N, Nguyen C, Brown BS, McNeish JD, Cohen AE, Kralj JM. Cardiotoxicity screening with simultaneous optogenetic pacing, voltage imaging and calcium imaging. J Pharmacol Toxicol Methods 2016; 81:240-50. [DOI: 10.1016/j.vascn.2016.05.003] [Citation(s) in RCA: 107] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Revised: 05/02/2016] [Accepted: 05/09/2016] [Indexed: 12/23/2022]
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19
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Klimas A, Ambrosi CM, Yu J, Williams JC, Bien H, Entcheva E. OptoDyCE as an automated system for high-throughput all-optical dynamic cardiac electrophysiology. Nat Commun 2016; 7:11542. [PMID: 27161419 PMCID: PMC4866323 DOI: 10.1038/ncomms11542] [Citation(s) in RCA: 107] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2015] [Accepted: 04/05/2016] [Indexed: 01/11/2023] Open
Abstract
The improvement of preclinical cardiotoxicity testing, discovery of new ion-channel-targeted drugs, and phenotyping and use of stem cell-derived cardiomyocytes and other biologics all necessitate high-throughput (HT), cellular-level electrophysiological interrogation tools. Optical techniques for actuation and sensing provide instant parallelism, enabling contactless dynamic HT testing of cells and small-tissue constructs, not affordable by other means. Here we show, computationally and experimentally, the limits of all-optical electrophysiology when applied to drug testing, then implement and validate OptoDyCE, a fully automated system for all-optical cardiac electrophysiology. We validate optical actuation by virally introducing optogenetic drivers in rat and human cardiomyocytes or through the modular use of dedicated light-sensitive somatic ‘spark' cells. We show that this automated all-optical approach provides HT means of cellular interrogation, that is, allows for dynamic testing of >600 multicellular samples or compounds per hour, and yields high-content information about the action of a drug over time, space and doses. The efficiency of preclinical drug testing and characterization of cellular function can be improved through the use of optogenetic tools. Here Klimas et al. present and validate OptoDyCE, a fully automated system for all-optical high-throughput cardiac electrophysiology.
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Affiliation(s)
- Aleksandra Klimas
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York, USA
| | - Christina M Ambrosi
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York, USA
| | - Jinzhu Yu
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York, USA
| | - John C Williams
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York, USA
| | - Harold Bien
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York, USA
| | - Emilia Entcheva
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York, USA
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20
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Variability of Action Potentials Within and Among Cardiac Cell Clusters Derived from Human Embryonic Stem Cells. Sci Rep 2016; 6:18544. [PMID: 26729331 PMCID: PMC4700458 DOI: 10.1038/srep18544] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 11/19/2015] [Indexed: 12/12/2022] Open
Abstract
Electrophysiological variability in cardiomyocytes derived from pluripotent stem cells continues to be an impediment for their scientific and translational applications. We studied the variability of action potentials (APs) recorded from clusters of human embryonic stem cell-derived cardiomyocytes (hESC-CMs) using high-resolution optical mapping. Over 23,000 APs were analyzed through four parameters: APD30, APD80, triangulation and fractional repolarization. Although measures were taken to reduce variability due to cell culture conditions and rate-dependency of APs, we still observed significant variability in APs among and within the clusters. However, similar APs were found in spatial locations with close proximity, and in some clusters formed distinct regions having different AP characteristics that were reflected as separate peaks in the AP parameter distributions, suggesting multiple electrophysiological phenotypes. Using a recently developed automated method to group cells based on their entire AP shape, we identified distinct regions of different phenotypes within single clusters and common phenotypes across different clusters when separating APs into 2 or 3 subpopulations. The systematic analysis of the heterogeneity and potential phenotypes of large populations of hESC-CMs can be used to evaluate strategies to improve the quality of pluripotent stem cell-derived cardiomyocytes for use in diagnostic and therapeutic applications and in drug screening.
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21
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Cardiac Optogenetics: Enhancement by All-trans-Retinal. Sci Rep 2015; 5:16542. [PMID: 26568132 PMCID: PMC4644984 DOI: 10.1038/srep16542] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2015] [Accepted: 10/15/2015] [Indexed: 11/30/2022] Open
Abstract
All-trans-Retinal (ATR) is a photosensitizer, serving as the chromophore for depolarizing and hyperpolarizing light-sensitive ion channels and pumps (opsins), recently employed as fast optical actuators. In mammalian optogenetic applications (in brain and heart), endogenous ATR availability is not considered a limiting factor, yet it is unclear how ATR modulation may affect the response to optical stimulation. We hypothesized that exogenous ATR may improve light responsiveness of cardiac cells modified by Channelrhodopsin2 (ChR2), hence lowering the optical pacing energy. In virally-transduced (Ad-ChR2(H134R)-eYFP) light-sensitive cardiac syncytium in vitro, ATR supplements ≤2 μM improved cardiomyocyte viability and augmented ChR2 membrane expression several-fold, while >4 μM was toxic. Employing integrated optical actuation (470 nm) and optical mapping, we found that 1–2 μM ATR dramatically reduced optical pacing energy (over 30 times) to several μW/mm2, lowest values reported to date, but also caused action potential prolongation, minor changes in calcium transients and no change in conduction. Theoretical analysis helped explain ATR-caused reduction of optical excitation threshold in cardiomyocytes. We conclude that cardiomyocytes operate at non-saturating retinal levels, and carefully-dosed exogenous ATR can enhance the performance of ChR2 in cardiac cells and yield energy benefits over orders of magnitude for optogenetic stimulation.
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Wang K, Lee P, Mirams GR, Sarathchandra P, Borg TK, Gavaghan DJ, Kohl P, Bollensdorff C. Cardiac tissue slices: preparation, handling, and successful optical mapping. Am J Physiol Heart Circ Physiol 2015; 308:H1112-25. [PMID: 25595366 PMCID: PMC4551126 DOI: 10.1152/ajpheart.00556.2014] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Accepted: 01/14/2015] [Indexed: 01/28/2023]
Abstract
Cardiac tissue slices are becoming increasingly popular as a model system for cardiac electrophysiology and pharmacology research and development. Here, we describe in detail the preparation, handling, and optical mapping of transmembrane potential and intracellular free calcium concentration transients (CaT) in ventricular tissue slices from guinea pigs and rabbits. Slices cut in the epicardium-tangential plane contained well-aligned in-slice myocardial cell strands (“fibers”) in subepicardial and midmyocardial sections. Cut with a high-precision slow-advancing microtome at a thickness of 350 to 400 μm, tissue slices preserved essential action potential (AP) properties of the precutting Langendorff-perfused heart. We identified the need for a postcutting recovery period of 36 min (guinea pig) and 63 min (rabbit) to reach 97.5% of final steady-state values for AP duration (APD) (identified by exponential fitting). There was no significant difference between the postcutting recovery dynamics in slices obtained using 2,3-butanedione 2-monoxime or blebistatin as electromechanical uncouplers during the cutting process. A rapid increase in APD, seen after cutting, was caused by exposure to ice-cold solution during the slicing procedure, not by tissue injury, differences in uncouplers, or pH-buffers (bicarbonate; HEPES). To characterize intrinsic patterns of CaT, AP, and conduction, a combination of multipoint and field stimulation should be used to avoid misinterpretation based on source-sink effects. In summary, we describe in detail the preparation, mapping, and data analysis approaches for reproducible cardiac tissue slice-based investigations into AP and CaT dynamics.
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Affiliation(s)
- Ken Wang
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
| | - Peter Lee
- Department of Physics, University of Oxford, Clarendon Laboratory, Oxford, United Kingdom
| | - Gary R Mirams
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
| | - Padmini Sarathchandra
- Harefield Heart Science Centre, National Heart and Lung Institute, Imperial College London, Middlesex, United Kingdom
| | - Thomas K Borg
- Department of Regenerative Medicine and Cell Biology, University of South Carolina School of Medicine, Charleston, South Carolina; and
| | - David J Gavaghan
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
| | - Peter Kohl
- Department of Computer Science, University of Oxford, Oxford, United Kingdom; Harefield Heart Science Centre, National Heart and Lung Institute, Imperial College London, Middlesex, United Kingdom
| | - Christian Bollensdorff
- Harefield Heart Science Centre, National Heart and Lung Institute, Imperial College London, Middlesex, United Kingdom; Qatar Cardiovascular Research Center, Qatar Foundation, Doha, Qatar
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Bub G, Burton RAB. Macro-micro imaging of cardiac-neural circuits in co-cultures from normal and diseased hearts. J Physiol 2014; 593:3047-53. [PMID: 25398529 DOI: 10.1113/jphysiol.2014.285460] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Accepted: 10/22/2014] [Indexed: 12/16/2022] Open
Abstract
The autonomic nervous system plays an important role in the modulation of normal cardiac rhythm, but is also implicated in modulating the heart's susceptibility to re-entrant ventricular and atrial arrhythmias. The mechanisms by which the autonomic nervous system is pro-arrhythmic or anti-arrhythmic is multifaceted and varies for different types of arrhythmia and their cardiac substrates. Despite decades of research in this area, fundamental questions related to how neuron density and spatial organization modulate cardiac wave dynamics remain unanswered. These questions may be ill-posed in intact tissues where the activity of individual cells is often experimentally inaccessible. Development of simplified biological models that would allow us to better understand the influence of neural activation on cardiac activity can be beneficial. This Symposium Review summarizes the development of in vitro cardiomyocyte cell culture models of re-entrant activity, as well as challenges associated with extending these models to include the effects of neural activation.
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Affiliation(s)
- Gil Bub
- Department of Physiology Anatomy and Genetics, University of Oxford, Oxford, OX1 3PT, UK
| | - Rebecca-Ann B Burton
- Department of Physiology Anatomy and Genetics, University of Oxford, Oxford, OX1 3PT, UK
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Hou JH, Kralj JM, Douglass AD, Engert F, Cohen AE. Simultaneous mapping of membrane voltage and calcium in zebrafish heart in vivo reveals chamber-specific developmental transitions in ionic currents. Front Physiol 2014; 5:344. [PMID: 25309445 PMCID: PMC4161048 DOI: 10.3389/fphys.2014.00344] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Accepted: 08/22/2014] [Indexed: 01/31/2023] Open
Abstract
The cardiac action potential (AP) and the consequent cytosolic Ca2+ transient are key indicators of cardiac function. Natural developmental processes, as well as many drugs and pathologies change the waveform, propagation, or variability (between cells or over time) of these parameters. Here we apply a genetically encoded dual-function calcium and voltage reporter (CaViar) to study the development of the zebrafish heart in vivo between 1.5 and 4 days post fertilization (dpf). We developed a high-sensitivity spinning disk confocal microscope and associated software for simultaneous three-dimensional optical mapping of voltage and calcium. We produced a transgenic zebrafish line expressing CaViar under control of the heart-specific cmlc2 promoter, and applied ion channel blockers at a series of developmental stages to map the maturation of the action potential in vivo. Early in development, the AP initiated via a calcium current through L-type calcium channels. Between 90 and 102 h post fertilization (hpf), the ventricular AP switched to a sodium-driven upswing, while the atrial AP remained calcium driven. In the adult zebrafish heart, a sodium current drives the AP in both the atrium and ventricle. Simultaneous voltage and calcium imaging with genetically encoded reporters provides a new approach for monitoring cardiac development, and the effects of drugs on cardiac function.
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Affiliation(s)
- Jennifer H Hou
- Department of Physics, Harvard University Cambridge, MA, USA
| | - Joel M Kralj
- Department of Chemistry and Chemical Biology, Harvard University Cambridge, MA, USA
| | - Adam D Douglass
- Department of Molecular and Cellular Biology, Harvard University Cambridge, MA, USA
| | - Florian Engert
- Department of Molecular and Cellular Biology, Harvard University Cambridge, MA, USA
| | - Adam E Cohen
- Department of Physics, Harvard University Cambridge, MA, USA ; Department of Chemistry and Chemical Biology, Harvard University Cambridge, MA, USA ; Howard Hughes Medical Institute Chevy Chase, MD, USA
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Klimas A, Entcheva E. Toward microendoscopy-inspired cardiac optogenetics in vivo: technical overview and perspective. JOURNAL OF BIOMEDICAL OPTICS 2014; 19:080701. [PMID: 25117076 PMCID: PMC4161000 DOI: 10.1117/1.jbo.19.8.080701] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Accepted: 07/17/2014] [Indexed: 05/13/2023]
Abstract
The ability to perform precise, spatially localized actuation and measurements of electrical activity in the heart is crucial in understanding cardiac electrophysiology and devising new therapeutic solutions for control of cardiac arrhythmias. Current cardiac imaging techniques (i.e. optical mapping) employ voltage- or calcium-sensitive fluorescent dyes to visualize the electrical signal propagation through cardiac syncytium in vitro or in situ with very high-spatiotemporal resolution. The extension of optogenetics into the cardiac field, where cardiac tissue is genetically altered to express light-sensitive ion channels allowing electrical activity to be elicited or suppressed in a precise cell-specific way, has opened the possibility for all-optical interrogation of cardiac electrophysiology. In vivo application of cardiac optogenetics faces multiple challenges and necessitates suitable optical systems employing fiber optics to actuate and sense electrical signals. In this technical perspective, we present a compendium of clinically relevant access routes to different parts of the cardiac electrical conduction system based on currently employed catheter imaging systems and determine the quantitative size constraints for endoscopic cardiac optogenetics. We discuss the relevant technical advancements in microendoscopy, cardiac imaging, and optogenetics and outline the strategies for combining them to create a portable, miniaturized fiber-based system for all-optical interrogation of cardiac electrophysiology in vivo.
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Affiliation(s)
- Aleksandra Klimas
- Stony Brook University, Department of Biomedical Engineering, Stony Brook, New York 11794, United States
| | - Emilia Entcheva
- Stony Brook University, Department of Biomedical Engineering, Stony Brook, New York 11794, United States
- Stony Brook University, Department of Physiology and Biophysics, Stony Brook, New York 11794, United States
- Stony Brook University, Institute for Molecular Cardiology, Stony Brook, New York 11794, United States
- Address all correspondence to: Emilia Entcheva, E-mail:
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Ambrosi CM, Klimas A, Yu J, Entcheva E. Cardiac applications of optogenetics. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2014; 115:294-304. [PMID: 25035999 DOI: 10.1016/j.pbiomolbio.2014.07.001] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 07/05/2014] [Indexed: 01/16/2023]
Abstract
In complex multicellular systems, such as the brain or the heart, the ability to selectively perturb and observe the response of individual components at the cellular level and with millisecond resolution in time, is essential for mechanistic understanding of function. Optogenetics uses genetic encoding of light sensitivity (by the expression of microbial opsins) to provide such capabilities for manipulation, recording, and control by light with cell specificity and high spatiotemporal resolution. As an optical approach, it is inherently scalable for remote and parallel interrogation of biological function at the tissue level; with implantable miniaturized devices, the technique is uniquely suitable for in vivo tracking of function, as illustrated by numerous applications in the brain. Its expansion into the cardiac area has been slow. Here, using examples from published research and original data, we focus on optogenetics applications to cardiac electrophysiology, specifically dealing with the ability to manipulate membrane voltage by light with implications for cardiac pacing, cardioversion, cell communication, and arrhythmia research, in general. We discuss gene and cell delivery methods of inscribing light sensitivity in cardiac tissue, functionality of the light-sensitive ion channels within different types of cardiac cells, utility in probing electrical coupling between different cell types, approaches and design solutions to all-optical electrophysiology by the combination of optogenetic sensors and actuators, and specific challenges in moving towards in vivo cardiac optogenetics.
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Affiliation(s)
- Christina M Ambrosi
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY 11794-8661, USA
| | - Aleksandra Klimas
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY 11794-8661, USA
| | - Jinzhu Yu
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY 11794-8661, USA
| | - Emilia Entcheva
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY 11794-8661, USA.
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Macadangdang J, Lee HJ, Carson D, Jiao A, Fugate J, Pabon L, Regnier M, Murry C, Kim DH. Capillary force lithography for cardiac tissue engineering. J Vis Exp 2014. [PMID: 24962161 DOI: 10.3791/50039] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Cardiovascular disease remains the leading cause of death worldwide(1). Cardiac tissue engineering holds much promise to deliver groundbreaking medical discoveries with the aims of developing functional tissues for cardiac regeneration as well as in vitro screening assays. However, the ability to create high-fidelity models of heart tissue has proven difficult. The heart's extracellular matrix (ECM) is a complex structure consisting of both biochemical and biomechanical signals ranging from the micro- to the nanometer scale(2). Local mechanical loading conditions and cell-ECM interactions have recently been recognized as vital components in cardiac tissue engineering(3-5). A large portion of the cardiac ECM is composed of aligned collagen fibers with nano-scale diameters that significantly influences tissue architecture and electromechanical coupling(2). Unfortunately, few methods have been able to mimic the organization of ECM fibers down to the nanometer scale. Recent advancements in nanofabrication techniques, however, have enabled the design and fabrication of scalable scaffolds that mimic the in vivo structural and substrate stiffness cues of the ECM in the heart(6-9). Here we present the development of two reproducible, cost-effective, and scalable nanopatterning processes for the functional alignment of cardiac cells using the biocompatible polymer poly(lactide-co-glycolide) (PLGA)(8) and a polyurethane (PU) based polymer. These anisotropically nanofabricated substrata (ANFS) mimic the underlying ECM of well-organized, aligned tissues and can be used to investigate the role of nanotopography on cell morphology and function(10-14). Using a nanopatterned (NP) silicon master as a template, a polyurethane acrylate (PUA) mold is fabricated. This PUA mold is then used to pattern the PU or PLGA hydrogel via UV-assisted or solvent-mediated capillary force lithography (CFL), respectively(15,16). Briefly, PU or PLGA pre-polymer is drop dispensed onto a glass coverslip and the PUA mold is placed on top. For UV-assisted CFL, the PU is then exposed to UV radiation (λ = 250-400 nm) for curing. For solvent-mediated CFL, the PLGA is embossed using heat (120 °C) and pressure (100 kPa). After curing, the PUA mold is peeled off, leaving behind an ANFS for cell culture. Primary cells, such as neonatal rat ventricular myocytes, as well as human pluripotent stem cell-derived cardiomyocytes, can be maintained on the ANFS(2).
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Affiliation(s)
| | - Hyun Jung Lee
- Department of Bioengineering, University of Washington
| | - Daniel Carson
- Department of Bioengineering, University of Washington
| | - Alex Jiao
- Department of Bioengineering, University of Washington
| | - James Fugate
- Department of Pathology, University of Washington
| | - Lil Pabon
- Department of Pathology, University of Washington
| | | | | | - Deok-Ho Kim
- Department of Bioengineering, University of Washington;
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Abstract
Optogenetics is an emerging technology for the manipulation and control of excitable tissues, such as the brain and heart. As this technique requires the genetic modification of cells in order to inscribe light sensitivity, for cardiac applications, here we describe the process through which neonatal rat ventricular myocytes are virally infected in vitro with channelrhodopsin-2 (ChR2). We also describe in detail the procedure for quantitatively determining the optimal viral dosage, including instructions for patterning gene expression in multicellular cardiomyocyte preparations (cardiac syncytia) to simulate potential in vivo transgene distributions. Finally, we address optical actuation of ChR2-transduced cells and means to measure their functional response to light.
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Tanaka Y, Takase B, Yao T, Ishihara M. Right Ventricular Electrical Remodeling and Arrhythmogenic Substrate in Rat Pulmonary Hypertension. Am J Respir Cell Mol Biol 2013; 49:426-36. [DOI: 10.1165/rcmb.2012-0089oc] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Abstract
Optogenetics is an emerging technology for optical interrogation and control of biological function with high specificity and high spatiotemporal resolution. Mammalian cells and tissues can be sensitized to respond to light by a relatively simple and well-tolerated genetic modification using microbial opsins (light-gated ion channels and pumps). These can achieve fast and specific excitatory or inhibitory response, offering distinct advantages over traditional pharmacological or electrical means of perturbation. Since the first demonstrations of utility in mammalian cells (neurons) in 2005, optogenetics has spurred immense research activity and has inspired numerous applications for dissection of neural circuitry and understanding of brain function in health and disease, applications ranging from in vitro to work in behaving animals. Only recently (since 2010), the field has extended to cardiac applications with less than a dozen publications to date. In consideration of the early phase of work on cardiac optogenetics and the impact of the technique in understanding another excitable tissue, the brain, this review is largely a perspective of possibilities in the heart. It covers the basic principles of operation of light-sensitive ion channels and pumps, the available tools and ongoing efforts in optimizing them, overview of neuroscience use, as well as cardiac-specific questions of implementation and ideas for best use of this emerging technology in the heart.
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Affiliation(s)
- Emilia Entcheva
- Department of Biomedical Engineering, Department of Physiology and Biophysics, and Institute for Molecular Cardiology, Stony Brook University, Stony Brook, New York, USA
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Abstract
The voltage-gated Na+ channel is a critical determinant of the action potential (AP) upstroke. Increasing Na+ conductance may speed AP propagation. In this study, we propose use of the skeletal muscle Na+ channel SkM1 as a more favorable gene than the cardiac isoform SCN5A to enhance conduction velocity in depolarized cardiac tissue. We used cells that electrically coupled with cardiac myocytes as a delivery platform to introduce the Na+ channels. Human embryonic kidney 293 cells were stably transfected with SkM1 or SCN5A. SkM1 had a more depolarized (18 mV shift) inactivation curve than SCN5A. We also found that SkM1 recovered faster from inactivation than SCN5A. When coupled with SkM1 expressing cells, cultured myocytes showed an increase in the dV/dtmax of the AP. Expression of SCN5A had no such effect. In an in vitro cardiac syncytium, coculture of neonatal cardiac myocytes with SkM1 expressing but not SCN5A expressing cells significantly increased the conduction velocity under both normal and depolarized conditions. In an in vitro reentry model induced by high-frequency stimulation, expression of SkM1 also enhanced angular velocity of the induced reentry. These results suggest that cells carrying a Na+ channel with a more depolarized inactivation curve can improve cardiac excitability and conduction in depolarized tissues.
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Abstract
Optical recording of membrane potential permits spatially resolved measurement of electrical activity in subcellular regions of single cells, which would be inaccessible to electrodes, and imaging of spatiotemporal patterns of action potential propagation in excitable tissues, such as the brain or heart. However, the available voltage-sensitive dyes (VSDs) are not always spectrally compatible with newly available optical technologies for sensing or manipulating the physiological state of a system. Here, we describe a series of 19 fluorinated VSDs based on the hemicyanine class of chromophores. Strategic placement of the fluorine atoms on the chromophores can result in either blue or red shifts in the absorbance and emission spectra. The range of one-photon excitation wavelengths afforded by these new VSDs spans 440-670 nm; the two-photon excitation range is 900-1,340 nm. The emission of each VSD is shifted by at least 100 nm to the red of its one-photon excitation spectrum. The set of VSDs, thus, affords an extended toolkit for optical recording to match a broad range of experimental requirements. We show the sensitivity to voltage and the photostability of the new VSDs in a series of experimental preparations ranging in scale from single dendritic spines to whole heart. Among the advances shown in these applications are simultaneous recording of voltage and calcium in single dendritic spines and optical electrophysiology recordings using two-photon excitation above 1,100 nm.
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Cardiac electrophysiological imaging systems scalable for high-throughput drug testing. Pflugers Arch 2012; 464:645-56. [PMID: 23053475 PMCID: PMC3513599 DOI: 10.1007/s00424-012-1149-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Revised: 08/22/2012] [Accepted: 08/24/2012] [Indexed: 12/02/2022]
Abstract
Multi-parametric electrophysiological measurements using optical methods have become a highly valued standard in cardiac research. Most published optical mapping systems are expensive and complex. Although some applications demand high-cost components and complex designs, many can be tackled with simpler solutions. Here, we describe (1) a camera-based voltage and calcium imaging system using a single ‘economy’ electron-multiplying charge-coupled device camera and demonstrate the possibility of using a consumer camera for imaging calcium transients of the heart, and (2) a photodiode-based voltage and calcium high temporal resolution measurement system using single-element photodiodes and an optical fibre. High-throughput drug testing represents an application where system scalability is particularly attractive. Therefore, we tested our systems on tissue exposed to a well-characterized and clinically relevant calcium channel blocker, nifedipine, which has been used to treat angina and hypertension. As experimental models, we used the Langendorff-perfused whole-heart and thin ventricular tissue slices, a preparation gaining renewed interest by the cardiac research community. Using our simplified systems, we were able to monitor simultaneously the marked changes in the voltage and calcium transients that are responsible for the negative inotropic effect of the compound.
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Shrivastav M, Ghai MB, Singal A, Iaizzo PA. The design and use of an optical mapping system for the study of intracardiac electrical signaling. Indian Pacing Electrophysiol J 2012; 12:138-51. [PMID: 22912535 PMCID: PMC3407407 DOI: 10.1016/s0972-6292(16)30521-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Fluorescent optical mapping of electrically active cardiac tissues provides a unique method to examine the excitation wave dynamics of underlying action potentials. Such mapping can be viewed as a bridge between cellular level and organ systems physiology, e.g., by facilitating the development of advanced theoretical concepts of arrhythmia. We present the design and use of a high-speed, high-resolution optical mapping system composed entirely of "off the shelf" components. The electrical design integrates a 256 element photodiode array with a 16 bit data acquisition system. Proper grounding and shielding at various stages of the design reduce electromagnetic interference. Our mechanical design provides flexibility in terms of mounting positions and applications (use for whole heart or tissue preparations), while maintaining precise alignment between all optical components. The system software incorporates a user friendly graphical user interface, e.g., spatially recorded action potentials can be represented as intensity graphs or in strip chart format. Thus, this system is capable of displaying cardiac action potentials with high spatiotemporal resolution. Results from cardiac action potential mapping with intact mouse hearts are provided. It should be noted that this system could be readily configured to study isolated myocardial biopsies (e.g., isolated ventricular trabeculae). We describe the details of a versatile, user-friendly system that could be employed for a magnitude of study protocols.
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Boink GJJ, Lu J, Driessen HE, Duan L, Sosunov EA, Anyukhovsky EP, Shlapakova IN, Lau DH, Rosen TS, Danilo P, Jia Z, Ozgen N, Bobkov Y, Guo Y, Brink PR, Kryukova Y, Robinson RB, Entcheva E, Cohen IS, Rosen MR. Effect of skeletal muscle Na(+) channel delivered via a cell platform on cardiac conduction and arrhythmia induction. Circ Arrhythm Electrophysiol 2012; 5:831-40. [PMID: 22722661 DOI: 10.1161/circep.111.969907] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
BACKGROUND In depolarized myocardial infarct epicardial border zones, the cardiac sodium channel is largely inactivated, contributing to slow conduction and reentry. We have demonstrated that adenoviral delivery of the skeletal muscle Na(+) channel (SkM1) to epicardial border zones normalizes conduction and reduces induction of ventricular tachycardia/ventricular fibrillation. We now studied the impact of canine mesenchymal stem cells (cMSCs) in delivering SkM1. METHODS AND RESULTS cMSCs were isolated and transfected with SkM1. Coculture experiments showed cMSC/SkM1 but not cMSC alone and maintained fast conduction at depolarized potentials. We studied 3 groups in the canine 7d infarct: sham, cMSC, and cMSC/SkM1. In vivo epicardial border zones electrograms were broad and fragmented in sham, narrower in cMSCs, and narrow and unfragmented in cMSC/SkM1 (P<0.05). During programmed electrical stimulation of epicardial border zones, QRS duration in cMSC/SkM1 was shorter than in cMSC and sham (P<0.05). Programmed electrical stimulation-induced ventricular tachycardia/ventricular fibrillation was equivalent in all groups (P>0.05). CONCLUSION cMSCs provide efficient delivery of SkM1 current. The interventions performed (cMSCs or cMSC/SkM1) were neither antiarrhythmic nor proarrhythmic. Comparing outcomes with cMSC/SkM1 and viral gene delivery highlights the criticality of the delivery platform to SkM1 antiarrhythmic efficacy.
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Affiliation(s)
- Gerard J J Boink
- Department of Pharmacology, Center for Molecular Therapeutics, Columbia University, New York, NY 10032, USA
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Hörning M, Takagi S, Yoshikawa K. Controlling activation site density by low-energy far-field stimulation in cardiac tissue. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 85:061906. [PMID: 23005126 DOI: 10.1103/physreve.85.061906] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Revised: 03/19/2012] [Indexed: 06/01/2023]
Abstract
Tachycardia and fibrillation are potentially fatal arrhythmias associated with the formation of rotating spiral waves in the heart. Presently, the termination of these types of arrhythmia is achieved by use of antitachycardia pacing or cardioversion. However, these techniques have serious drawbacks, in that they either have limited application or produce undesirable side effects. Low-energy far-field stimulation has recently been proposed as a superior therapy. This proposed therapeutic method would exploit the phenomenon in which the application of low-energy far-field shocks induces a large number of activation sites ("virtual electrodes") in tissue. It has been found that the formation of such sites can lead to the termination of undesired states in the heart and the restoration of normal beating. In this study we investigate a particular aspect of this method. Here we seek to determine how the activation site density depends on the applied electric field through in vitro experiments carried out on neonatal rat cardiac tissue cultures. The results indicate that the activation site density increases exponentially as a function of the intracellular conductivity and the level of cell isotropy. Additionally, we report numerical results obtained from bidomain simulations of the Beeler-Reuter model that are quantitatively consistent with our experimental results. Also, we derive an intuitive analytical framework that describes the activation site density and provides useful information for determining the ratio of longitudinal to transverse conductivity in a cardiac tissue culture. The results obtained here should be useful in the development of an actual therapeutic method based on low-energy far-field pacing. In addition, they provide a deeper understanding of the intrinsic properties of cardiac cells.
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Affiliation(s)
- Marcel Hörning
- Department of Physics, Graduate School of Science, Kyoto University, Japan.
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37
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Abstract
Cardiac optical mapping has proven to be a powerful technology for studying cardiovascular function and disease. The development and scientific impact of this methodology are well-documented. Because of its relevance in cardiac research, this imaging technology advances at a rapid pace. Here, we review technological and scientific developments during the past several years and look toward the future. First, we explore key components of a modern optical mapping set-up, focusing on: (1) new camera technologies; (2) powerful light-emitting-diodes (from ultraviolet to red) for illumination; (3) improved optical filter technology; (4) new synthetic and optogenetic fluorescent probes; (5) optical mapping with motion and contraction; (6) new multiparametric optical mapping techniques; and (7) photon scattering effects in thick tissue preparations. We then look at recent optical mapping studies in single cells, cardiomyocyte monolayers, atria, and whole hearts. Finally, we briefly look into the possible future roles of optical mapping in the development of regenerative cardiac research, cardiac cell therapies, and molecular genetic advances.
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Affiliation(s)
- Todd J Herron
- Department of Internal Medicine, Cardiovascular Research Center, University of Michigan, 2800 Plymouth Road, Ann Arbor, MI 48109-2800, USA
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38
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Cardiac cellular coupling and the spread of early instabilities in intracellular Ca2+. Biophys J 2012; 102:1294-302. [PMID: 22455912 DOI: 10.1016/j.bpj.2012.02.034] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2011] [Revised: 02/09/2012] [Accepted: 02/17/2012] [Indexed: 11/23/2022] Open
Abstract
Recent experimental and modeling studies demonstrate the fine spatial scale, complex nature, and independent contribution of Ca(2+) dynamics as a proarrhythmic factor in the heart. The mechanism of progression of cell-level Ca(2+) instabilities, known as alternans, to tissue-level arrhythmias is not well understood. Because gap junction coupling dictates cardiac syncytial properties, we set out to elucidate its role in the spatiotemporal evolution of Ca(2+) instabilities. We experimentally perturbed cellular coupling in cardiac syncytium in vitro. Coupling was quantified by fluorescence recovery after photobleaching, and related to function, including subtle fine-scale Ca(2+) alternans, captured by optical mapping. Conduction velocity and threshold for alternans monotonically increased with coupling. Lower coupling enhanced Ca(2+) alternans amplitude, but the spatial spread of early (<2 Hz) alternation was the greatest under intermediate (not low) coupling. This nonmonotonic relationship was closely matched by the percent of samples exhibiting large-scale alternans at higher pacing rates. Computer modeling corroborated these experimental findings for strong but not weak electromechanical (voltage-Ca(2+)) coupling, and offered mechanistic insight. In conclusion, using experimental and modeling approaches, we reveal a general mechanism for the spatial spread of subtle cellular Ca(2+) alternans that relies on a combination of gap-junctional and voltage-Ca(2+) coupling.
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Hörning M, Kidoaki S, Kawano T, Yoshikawa K. Rigidity matching between cells and the extracellular matrix leads to the stabilization of cardiac conduction. Biophys J 2012; 102:379-87. [PMID: 22325259 PMCID: PMC3274804 DOI: 10.1016/j.bpj.2011.12.018] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Revised: 12/04/2011] [Accepted: 12/12/2011] [Indexed: 11/15/2022] Open
Abstract
Biomechanical dynamic interactions between cells and the extracellular environment dynamically regulate physiological tissue behavior in living organisms, such as that seen in tissue maintenance and remodeling. In this study, the substrate-induced modulation of synchronized beating in cultured cardiomyocyte tissue was systematically characterized on elasticity-tunable substrates to elucidate the effect of biomechanical coupling. We found that myocardial conduction is significantly promoted when the rigidity of the cell culture environment matches that of the cardiac cells (4 kiloPascals). The stability of spontaneous target wave activity and calcium transient alternans in high frequency-paced tissue were both enhanced when the cell substrate and cell tissue showed the same rigidity. By adapting a simple theoretical model, we reproduced the experimental trend on the rigidity matching for the synchronized excitation. We conclude that rigidity matching in cell-to-substrate interactions critically improves cardiomyocyte-tissue synchronization, suggesting that mechanical coupling plays an essential role in the dynamic activity of the beating heart.
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Affiliation(s)
- Marcel Hörning
- Department of Physics, Graduate School of Science, Kyoto University, Japan
| | - Satoru Kidoaki
- Division of Biomolecular Chemistry, Institute for Materials Chemistry and Engineering, Kyushu University, Fukuoka, Japan
| | - Takahito Kawano
- Division of Biomolecular Chemistry, Institute for Materials Chemistry and Engineering, Kyushu University, Fukuoka, Japan
| | - Kenichi Yoshikawa
- Department of Physics, Graduate School of Science, Kyoto University, Japan
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Jia Z, Valiunas V, Lu Z, Bien H, Liu H, Wang HZ, Rosati B, Brink PR, Cohen IS, Entcheva E. Stimulating cardiac muscle by light: cardiac optogenetics by cell delivery. Circ Arrhythm Electrophysiol 2011; 4:753-60. [PMID: 21828312 DOI: 10.1161/circep.111.964247] [Citation(s) in RCA: 140] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND After the recent cloning of light-sensitive ion channels and their expression in mammalian cells, a new field, optogenetics, emerged in neuroscience, allowing for precise perturbations of neural circuits by light. However, functionality of optogenetic tools has not been fully explored outside neuroscience, and a nonviral, nonembryogenesis-based strategy for optogenetics has not been shown before. METHODS AND RESULTS We demonstrate the utility of optogenetics to cardiac muscle by a tandem cell unit (TCU) strategy, in which nonexcitable cells carry exogenous light-sensitive ion channels, and, when electrically coupled to cardiomyocytes, produce optically excitable heart tissue. A stable channelrhodopsin2 (ChR2)-expressing cell line was developed, characterized, and used as a cell delivery system. The TCU strategy was validated in vitro in cell pairs with adult canine myocytes (for a wide range of coupling strengths) and in cardiac syncytium with neonatal rat cardiomyocytes. For the first time, we combined optical excitation and optical imaging to capture light-triggered muscle contractions and high-resolution propagation maps of light-triggered electric waves, found to be quantitatively indistinguishable from electrically triggered waves. CONCLUSIONS Our results demonstrate feasibility to control excitation and contraction in cardiac muscle by light, using the TCU approach. Optical pacing in this case uses less energy, offers superior spatiotemporal control and remote access and can serve not only as an elegant tool in arrhythmia research but may form the basis for a new generation of light-driven cardiac pacemakers and muscle actuators. The TCU strategy is extendable to (nonviral) stem cell therapy and is directly relevant to in vivo applications.
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Affiliation(s)
- Zhiheng Jia
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY 11794-8181, USA
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41
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Lee P, Bollensdorff C, Quinn TA, Wuskell JP, Loew LM, Kohl P. Single-sensor system for spatially resolved, continuous, and multiparametric optical mapping of cardiac tissue. Heart Rhythm 2011; 8:1482-91. [PMID: 21459161 PMCID: PMC3167353 DOI: 10.1016/j.hrthm.2011.03.061] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2011] [Accepted: 03/28/2011] [Indexed: 11/28/2022]
Abstract
Background Simultaneous optical mapping of multiple electrophysiologically relevant parameters in living myocardium is desirable for integrative exploration of mechanisms underlying heart rhythm generation under normal and pathophysiologic conditions. Current multiparametric methods are technically challenging, usually involving multiple sensors and moving parts, which contributes to high logistic and economic thresholds that prevent easy application of the technique. Objective The purpose of this study was to develop a simple, affordable, and effective method for spatially resolved, continuous, simultaneous, and multiparametric optical mapping of the heart, using a single camera. Methods We present a new method to simultaneously monitor multiple parameters using inexpensive off-the-shelf electronic components and no moving parts. The system comprises a single camera, commercially available optical filters, and light-emitting diodes (LEDs), integrated via microcontroller-based electronics for frame-accurate illumination of the tissue. For proof of principle, we illustrate measurement of four parameters, suitable for ratiometric mapping of membrane potential (di-4-ANBDQPQ) and intracellular free calcium (fura-2), in an isolated Langendorff-perfused rat heart during sinus rhythm and ectopy, induced by local electrical or mechanical stimulation. Results The pilot application demonstrates suitability of this imaging approach for heart rhythm research in the isolated heart. In addition, locally induced excitation, whether stimulated electrically or mechanically, gives rise to similar ventricular propagation patterns. Conclusion Combining an affordable camera with suitable optical filters and microprocessor-controlled LEDs, single-sensor multiparametric optical mapping can be practically implemented in a simple yet powerful configuration and applied to heart rhythm research. The moderate system complexity and component cost is destined to lower the threshold to broader application of functional imaging and to ease implementation of more complex optical mapping approaches, such as multiparametric panoramic imaging. A proof-of-principle application confirmed that although electrically and mechanically induced excitation occur by different mechanisms, their electrophysiologic consequences downstream from the point of activation are not dissimilar.
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Affiliation(s)
- Peter Lee
- Cardiac Mechano-Electric Feedback Lab, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
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Hama N, Ito SI, Hirota A. An improved multiple-site optical membrane potential-recording system to obtain high-quality single sweep signals in intact rat cerebral cortex. J Neurosci Methods 2010; 194:73-80. [DOI: 10.1016/j.jneumeth.2010.09.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2010] [Revised: 09/14/2010] [Accepted: 09/21/2010] [Indexed: 11/26/2022]
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43
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Kanu UB, Iravanian S, Gilmour RF, Christini DJ. Control of action potential duration alternans in canine cardiac ventricular tissue. IEEE Trans Biomed Eng 2010; 58:894-904. [PMID: 21041155 DOI: 10.1109/tbme.2010.2089984] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Cardiac electrical alternans, characterized by a beat-to-beat alternation in action potential waveform, is a naturally occurring phenomenon, which can occur at sufficiently fast pacing rates. Its presence has been putatively linked to the onset of cardiac reentry, which is a precursor to ventricular fibrillation. Previous studies have shown that closed-loop alternans control techniques that apply a succession of externally administered cycle perturbations at a single site provide limited spatially-extended alternans elimination in sufficiently large cardiac substrates. However, detailed experimental investigations into the spatial dynamics of alternans control have been restricted to Purkinje fiber studies. A complete understanding of alternans control in the more clinically relevant ventricular tissue is needed. In this paper, we study the spatial dynamics of alternans and alternans control in arterially perfused canine right ventricular preparations using an optical mapping system capable of high-resolution fluorescence imaging. Specifically, we quantify the spatial efficacy of alternans control along 2.5 cm of tissue, focusing on differences in spatial control between different subregions of tissue. We demonstrate effective control of spatially-extended alternans up to 2.0 cm, with control efficacy attenuating as a function of distance. Our results provide a basis for future investigations into electrode-based control interventions of alternans in cardiac tissue.
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Affiliation(s)
- Uche B Kanu
- Department of Biomedical Engineering, Cornell University, Ithaca, NY 14853, USA.
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Hörning M, Takagi S, Yoshikawa K. Wave emission on interacting heterogeneities in cardiac tissue. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 82:021926. [PMID: 20866856 DOI: 10.1103/physreve.82.021926] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2010] [Revised: 07/27/2010] [Indexed: 05/29/2023]
Abstract
Cardiac arrhythmias, a precursor of fibrillationlike states in the beating heart, are associated with spiral waves, which are likely to become pinned to heterogeneities. Far-field pacing (FFP) is a promising method for terminating such waves by using heterogeneities in the tissue as internal pacing sites. In this study we investigated the role of multiple obstacles and their interaction during FFP. We show that a secondary nearby obstacle can significantly modulate the minimum electrical field in FFP. Further, we show that essentially the same effect can be observed in cardiac tissue culture, which is a powerful experimental model to simulate heart activity. Here, an isotropic cell distribution leads to domain formation of locally distributed depolarization sites. Both secondary obstacles and domain formation of local depolarization sites can modulate energy requirements to originate wave propagation on obstacles. Our theoretical result was confirmed by experiments with cardiomyocyte monolayers. This result may be useful for the future application of FFP to a real beating heart.
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Bub G, Tecza M, Helmes M, Lee P, Kohl P. Temporal pixel multiplexing for simultaneous high-speed, high-resolution imaging. Nat Methods 2010; 7:209-11. [PMID: 20154677 PMCID: PMC2873566 DOI: 10.1038/nmeth.1429] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2009] [Accepted: 01/04/2010] [Indexed: 11/11/2022]
Abstract
We introduce an imaging modality that, by offsetting pixel-exposure times during capture of a single image frame, embeds temporal information in each frame. This allows simultaneous acquisition of full-resolution images at native detector frame rates and high-speed image sequences at reduced resolution, without increasing bandwidth requirements. We demonstrate this method using macroscopic and microscopic examples, including imaging calcium transients in heart cells at 250 Hz using a 10-Hz megapixel camera.
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Affiliation(s)
- Gil Bub
- Department of Physiology Anatomy and Genetics, Oxford, UK.
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Abstract
The use of stem cells for cardiac regeneration is a revolutionary, emerging research area. For proper function as replacement tissue, stem cell-derived cardiomyocytes (SC-CMs) must electrically couple with the host cardiac tissue. Electrophysiological mapping techniques, including microelectrode array (MEA) and optical mapping, have been developed to study cardiomyocytes and cardiac cell monolayers, and these can be applied to study stem cells and SC-CMs. MEA recordings take extracellular measurements at numerous points across a small area of cell cultures and are used to assess electrical propagation during cell culture. Optical mapping uses fluorescent dyes to monitor electrophysiological changes in cells, most commonly transmembrane potential and intracellular calcium, and can be easily scaled to areas of different sizes. The materials and methods for MEA and optical mapping are presented here, together with detailed notes on their use, design, and fabrication. We also provide examples of voltage and calcium maps of mouse embryonic stem cell-derived cardiomyocytes (mESC-CMs), obtained in our laboratory using optical mapping techniques.
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Affiliation(s)
- Seth Weinberg
- Department of Biomedical Engineering, The Johns Hopkins University, Baltimore, MD, USA
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Bildgebung und Bildverarbeitung. BIOMED ENG-BIOMED TE 2010. [DOI: 10.1515/bmt.2010.701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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48
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Interrogating functional integration between injected pluripotent stem cell-derived cells and surrogate cardiac tissue. Proc Natl Acad Sci U S A 2009; 107:3329-34. [PMID: 19846783 DOI: 10.1073/pnas.0905729106] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Myocardial infarction resulting in irreversible loss of cardiomyocytes (CMs) remains a leading cause of heart failure. Although cell transplantation has modestly improved cardiac function, major challenges including increasing cell survival, engraftment, and functional integration with host tissue, remain. Embryonic stem cells (ESCs), which can be differentiated into cardiac progenitors (CPs) and CMs, represent a candidate cell source for cardiac cell therapy. However, it is not known what specific cell type or condition is the most appropriate for transplantation. This problem is exasperated by the lack of efficient and predictive strategies to screen the large numbers of parameters that may impact cell transplantation. We used a cardiac tissue model, engineered heart tissue (EHT), and quantitative molecular and electrophysiological analyses, to test transplantation conditions and specific cell populations for their potential to functionally integrate with the host tissue. In this study, we validated our analytical platform using contractile mouse neonatal CMs (nCMs) and noncontractile cardiac fibroblasts (cFBs), and screened for the integration potential of ESC-derived CMs and CPs (ESC-CMs and -CPs). Consistent with previous in vivo studies, cFB injection interfered with electrical signal propagation, whereas injected nCMs improved tissue function. Purified bioreactor-generated ESC-CMs exhibited a diminished capacity for electrophysiological integration; a result correlated with lower (compared with nCMs) connexin 43 expression. ESC-CPs, however, appeared able to appropriately mature and integrate into EHT, enhancing the amplitude of tissue contraction. Our results support the use of EHT as a model system to accelerate development of cardiac cell therapy strategies.
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Salama G, Hwang SM. Simultaneous optical mapping of intracellular free calcium and action potentials from Langendorff perfused hearts. ACTA ACUST UNITED AC 2009; Chapter 12:Unit 12.17. [PMID: 19575468 DOI: 10.1002/0471142956.cy1217s49] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The cardiac action potential (AP) controls the rise and fall of intracellular free Ca2+ (Ca(i)), and thus the amplitude and kinetics of force generation. Besides excitation-contraction coupling, the reverse process where Ca(i) influences the AP through Ca(i)-dependent ionic currents has been implicated as the mechanism underlying QT alternans and cardiac arrhythmias in heart failure, ischemia/reperfusion, cardiac myopathy, myocardial infarction, congenital and drug-induced long QT syndrome, and ventricular fibrillation. The development of dual optical mapping at high spatial and temporal resolution provides a powerful tool to investigate the role of Ca(i) anomalies in eliciting cardiac arrhythmias. This unit describes experimental protocols to map APs and Ca(i) transients from perfused hearts by labeling the heart with two fluorescent dyes, one to measure transmembrane potential (Vm), the other Ca(i) transients. High spatial and temporal resolution is achieved by selecting Vm and Ca(i) probes with the same excitation but different emission wavelengths, to avoid cross-talk and mechanical components.
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Affiliation(s)
- Guy Salama
- University of Pittsburgh, Pittsburgh, Pennsylvania, USA
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50
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Jia Z, Bien H, Entcheva E. Detecting space-time alternating biological signals close to the bifurcation point. IEEE Trans Biomed Eng 2009; 57:316-24. [PMID: 19695992 DOI: 10.1109/tbme.2009.2028652] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Time-alternating biological signals, i.e., alternans, arise in variety of physiological states marked by dynamic instabilities, e.g., period doubling. Normally, a sequence of large-small-large transients, they can exhibit variable patterns over time and space, including spatial discordance. Capture of the early formation of such alternating regions is challenging because of the spatiotemporal similarities between noise and the small-amplitude alternating signals close to the bifurcation point. We present a new approach for automatic detection of alternating signals in large noisy spatiotemporal datasets by exploiting quantitative measures of alternans evolution, e.g., temporal persistence, and by preserving phase information. The technique specifically targets low amplitude, relatively short alternating sequences and is validated by combinatorics-derived probabilities and empirical datasets with white noise. Using high-resolution optical mapping in live cardiomyocyte networks, exhibiting calcium alternans, we reveal for the first time early fine-scale alternans, close to the noise level, which are linked to the later formation of larger regions and evolution of spatially discordant alternans. This robust method aims at quantification and better understanding of the onset of cardiac arrhythmias and can be applied to general analysis of space-time alternating signals, including the vicinity of the bifurcation point.
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Affiliation(s)
- Zhiheng Jia
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY 11794, USA.
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