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Abstract
The electromechanical function of the heart involves complex, coordinated activity over time and space. Life-threatening cardiac arrhythmias arise from asynchrony in these space-time events; therefore, therapies for prevention and treatment require fundamental understanding and the ability to visualize, perturb and control cardiac activity. Optogenetics combines optical and molecular biology (genetic) approaches for light-enabled sensing and actuation of electrical activity with unprecedented spatiotemporal resolution and parallelism. The year 2020 marks a decade of developments in cardiac optogenetics since this technology was adopted from neuroscience and applied to the heart. In this Review, we appraise a decade of advances that define near-term (immediate) translation based on all-optical electrophysiology, including high-throughput screening, cardiotoxicity testing and personalized medicine assays, and long-term (aspirational) prospects for clinical translation of cardiac optogenetics, including new optical therapies for rhythm control. The main translational opportunities and challenges for optogenetics to be fully embraced in cardiology are also discussed.
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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: 6.2] [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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Deán-Ben XL, Gottschalk S, Sela G, Shoham S, Razansky D. Functional optoacoustic neuro-tomography of calcium fluxes in adult zebrafish brain in vivo. OPTICS LETTERS 2017; 42:959-962. [PMID: 28248341 DOI: 10.1364/ol.42.000959] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Genetically-encoded calcium indicators (GECIs) have revolutionized neuroimaging by enabling mapping of the activity of entire neuronal populations in vivo. Visualization of these powerful activity sensors has to date been limited to depth-restricted microscopic studies due to intense light scattering in the brain. We demonstrate, for the first time, in vivo real-time volumetric optoacoustic monitoring of calcium transients in adult transgenic zebrafish expressing the GCaMP5G calcium indicator. Fast changes in optoacoustic traces associated with GCaMP5G activity were detectable in the presence of other strongly absorbing endogenous chromophores, such as hemoglobin. The new functional optoacoustic neuroimaging method can visualize neural activity at penetration depths and spatio-temporal resolution scales not covered with the existing neuroimaging techniques.
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Nakajima R, Jung A, Yoon BJ, Baker BJ. Optogenetic Monitoring of Synaptic Activity with Genetically Encoded Voltage Indicators. Front Synaptic Neurosci 2016; 8:22. [PMID: 27547183 PMCID: PMC4974255 DOI: 10.3389/fnsyn.2016.00022] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 07/25/2016] [Indexed: 11/13/2022] Open
Abstract
The age of genetically encoded voltage indicators (GEVIs) has matured to the point that changes in membrane potential can now be observed optically in vivo. Improving the signal size and speed of these voltage sensors has been the primary driving forces during this maturation process. As a result, there is a wide range of probes using different voltage detecting mechanisms and fluorescent reporters. As the use of these probes transitions from optically reporting membrane potential in single, cultured cells to imaging populations of cells in slice and/or in vivo, a new challenge emerges—optically resolving the different types of neuronal activity. While improvements in speed and signal size are still needed, optimizing the voltage range and the subcellular expression (i.e., soma only) of the probe are becoming more important. In this review, we will examine the ability of recently developed probes to report synaptic activity in slice and in vivo. The voltage-sensing fluorescent protein (VSFP) family of voltage sensors, ArcLight, ASAP-1, and the rhodopsin family of probes are all good at reporting changes in membrane potential, but all have difficulty distinguishing subthreshold depolarizations from action potentials and detecting neuronal inhibition when imaging populations of cells. Finally, we will offer a few possible ways to improve the optical resolution of the various types of neuronal activities.
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Affiliation(s)
- Ryuichi Nakajima
- Center for Functional Connectomics, Korea Institute of Science and Technology Seongbuk-gu, Seoul, South Korea
| | - Arong Jung
- Center for Functional Connectomics, Korea Institute of Science and TechnologySeongbuk-gu, Seoul, South Korea; College of Life Sciences and Biotechnology, Korea UniversitySeongbuk-gu, Seoul, South Korea
| | - Bong-June Yoon
- College of Life Sciences and Biotechnology, Korea University Seongbuk-gu, Seoul, South Korea
| | - Bradley J Baker
- Center for Functional Connectomics, Korea Institute of Science and TechnologySeongbuk-gu, Seoul, South Korea; Department of Neuroscience, Korea University of Science and TechnologyDaejeon, South Korea
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Genetically Encoded Voltage Indicators in Circulation Research. Int J Mol Sci 2015; 16:21626-42. [PMID: 26370981 PMCID: PMC4613271 DOI: 10.3390/ijms160921626] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Revised: 08/27/2015] [Accepted: 08/31/2015] [Indexed: 01/18/2023] Open
Abstract
Membrane potentials display the cellular status of non-excitable cells and mediate communication between excitable cells via action potentials. The use of genetically encoded biosensors employing fluorescent proteins allows a non-invasive biocompatible way to read out the membrane potential in cardiac myocytes and other cells of the circulation system. Although the approaches to design such biosensors date back to the time when the first fluorescent-protein based Förster Resonance Energy Transfer (FRET) sensors were constructed, it took 15 years before reliable sensors became readily available. Here, we review different developments of genetically encoded membrane potential sensors. Furthermore, it is shown how such sensors can be used in pharmacological screening applications as well as in circulation related basic biomedical research. Potentials and limitations will be discussed and perspectives of possible future developments will be provided.
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Mutoh H, Mishina Y, Gallero-Salas Y, Knöpfel T. Comparative performance of a genetically-encoded voltage indicator and a blue voltage sensitive dye for large scale cortical voltage imaging. Front Cell Neurosci 2015; 9:147. [PMID: 25964738 PMCID: PMC4408844 DOI: 10.3389/fncel.2015.00147] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Accepted: 03/30/2015] [Indexed: 11/13/2022] Open
Abstract
Traditional small molecule voltage sensitive dye indicators have been a powerful tool for monitoring large scale dynamics of neuronal activities but have several limitations including the lack of cell class specific targeting, invasiveness and difficulties in conducting longitudinal studies. Recent advances in the development of genetically-encoded voltage indicators have successfully overcome these limitations. Genetically-encoded voltage indicators (GEVIs) provide sufficient sensitivity to map cortical representations of sensory information and spontaneous network activities across cortical areas and different brain states. In this study, we directly compared the performance of a prototypic GEVI, VSFP2.3, with that of a widely used small molecule voltage sensitive dye (VSD), RH1691, in terms of their ability to resolve mesoscopic scale cortical population responses. We used three synchronized CCD cameras to simultaneously record the dual emission ratiometric fluorescence signal from VSFP2.3 and RH1691 fluorescence. The results show that VSFP2.3 offers more stable and less invasive recording conditions, while the signal-to-noise level and the response dynamics to sensory inputs are comparable to RH1691 recordings.
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Affiliation(s)
- Hiroki Mutoh
- Department of Neurophysiology, Hamamatsu University School of Medicine Hamamatsu, Japan ; Laboratory for Neuronal Circuit Dynamics, RIKEN Brain Science Institute Wako City, Japan
| | - Yukiko Mishina
- Laboratory for Neuronal Circuit Dynamics, RIKEN Brain Science Institute Wako City, Japan ; Centre for Global Communication Strategies The University of Tokyo, Tokyo Japan
| | - Yasir Gallero-Salas
- Division of Brain Sciences, Department of Medicine, Imperial College London London, UK
| | - Thomas Knöpfel
- Laboratory for Neuronal Circuit Dynamics, RIKEN Brain Science Institute Wako City, Japan ; Division of Brain Sciences, Department of Medicine, Imperial College London London, UK
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Akemann W, Song C, Mutoh H, Knöpfel T. Route to genetically targeted optical electrophysiology: development and applications of voltage-sensitive fluorescent proteins. NEUROPHOTONICS 2015; 2:021008. [PMID: 26082930 PMCID: PMC4465821 DOI: 10.1117/1.nph.2.2.021008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Accepted: 12/11/2014] [Indexed: 06/04/2023]
Abstract
The invention of membrane voltage protein indicators widens the reach of optical voltage imaging in cell physiology, most notably neurophysiology, by enabling membrane voltage recordings from genetically defined cell types in chronic and life-long preparations. While the last years have seen a dramatic improvement in the technical performance of these indicators, concomitant innovations in optogenetics, optical axon tracing, and high-speed digital microscopy are beginning to fulfill the age-old vision of an all-optical analysis of neuronal circuits, reaching beyond the limits of traditional electrode-based recordings. We will present our personal account of the development of protein voltage indicators from the pioneering days to the present state, including their applications in neurophysiology that has inspired our own work for more than a decade.
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Affiliation(s)
- Walther Akemann
- Imperial College London, Department of Medicine, London W12 ONN, United Kingdom
- Institute of Biology, CNRS UMR 8197, École Normale Supérieure, 46 rue d’Ulm, 75005 Paris, France
| | - Chenchen Song
- Imperial College London, Department of Medicine, London W12 ONN, United Kingdom
| | - Hiroki Mutoh
- Hamamatsu University School of Medicine, Department of Neurophysiology, Shizuoka 431-3192, Japan
| | - Thomas Knöpfel
- Imperial College London, Department of Medicine, London W12 ONN, United Kingdom
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Mishina Y, Mutoh H, Song C, Knöpfel T. Exploration of genetically encoded voltage indicators based on a chimeric voltage sensing domain. Front Mol Neurosci 2014; 7:78. [PMID: 25324718 PMCID: PMC4179510 DOI: 10.3389/fnmol.2014.00078] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Accepted: 09/14/2014] [Indexed: 11/13/2022] Open
Abstract
Deciphering how the brain generates cognitive function from patterns of electrical signals is one of the ultimate challenges in neuroscience. To this end, it would be highly desirable to monitor the activities of very large numbers of neurons while an animal engages in complex behaviors. Optical imaging of electrical activity using genetically encoded voltage indicators (GEVIs) has the potential to meet this challenge. Currently prevalent GEVIs are based on the voltage-sensitive fluorescent protein (VSFP) prototypical design or on the voltage-dependent state transitions of microbial opsins. We recently introduced a new VSFP design in which the voltage-sensing domain (VSD) is sandwiched between a fluorescence resonance energy transfer pair of fluorescent proteins (termed VSFP-Butterflies) and also demonstrated a series of chimeric VSD in which portions of the VSD of Ciona intestinalis voltage-sensitive phosphatase are substituted by homologous portions of a voltage-gated potassium channel subunit. These chimeric VSD had faster sensing kinetics than that of the native Ci-VSD. Here, we describe a new set of VSFPs that combine chimeric VSD with the Butterfly structure. We show that these chimeric VSFP-Butterflies can report membrane voltage oscillations of up to 200 Hz in cultured cells and report sensory evoked cortical population responses in living mice. This class of GEVIs may be suitable for imaging of brain rhythms in behaving mammalians.
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Affiliation(s)
- Yukiko Mishina
- Laboratory for Neuronal Circuit Dynamics, RIKEN Brain Science Institute Wako, Japan ; Centre for Global Communication Strategies, The University of Tokyo Tokyo, Japan
| | - Hiroki Mutoh
- Laboratory for Neuronal Circuit Dynamics, RIKEN Brain Science Institute Wako, Japan ; Department of Neurophysiology, Hamamatsu University School of Medicine Shizuoka, Japan
| | - Chenchen Song
- Division of Brain Sciences, Department of Medicine, Imperial College London London, UK
| | - Thomas Knöpfel
- Laboratory for Neuronal Circuit Dynamics, RIKEN Brain Science Institute Wako, Japan ; Division of Brain Sciences, Department of Medicine, Imperial College London London, UK
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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: 2.6] [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: 4.9] [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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Pollock JD, Wu DY, Satterlee JS. Molecular neuroanatomy: a generation of progress. Trends Neurosci 2014; 37:106-23. [PMID: 24388609 PMCID: PMC3946666 DOI: 10.1016/j.tins.2013.11.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Revised: 11/08/2013] [Accepted: 11/14/2013] [Indexed: 11/22/2022]
Abstract
The neuroscience research landscape has changed dramatically over the past decade. Specifically, an impressive array of new tools and technologies have been generated, including but not limited to: brain gene expression atlases, genetically encoded proteins to monitor and manipulate neuronal activity, and new methods for imaging and mapping circuits. However, despite these technological advances, several significant challenges must be overcome to enable a better understanding of brain function and to develop cell type-targeted therapeutics to treat brain disorders. This review provides an overview of some of the tools and technologies currently being used to advance the field of molecular neuroanatomy, and also discusses emerging technologies that may enable neuroscientists to address these crucial scientific challenges over the coming decade.
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Affiliation(s)
- Jonathan D Pollock
- Division of Basic Neurobiology and Behavioral Research, Genetics and Molecular Neurobiology Research Branch, National Institute on Drug Abuse/National Institutes of Health (NIH), 6001 Executive Boulevard, Bethesda, MD 20850, USA.
| | - Da-Yu Wu
- Division of Basic Neurobiology and Behavioral Research, Genetics and Molecular Neurobiology Research Branch, National Institute on Drug Abuse/National Institutes of Health (NIH), 6001 Executive Boulevard, Bethesda, MD 20850, USA
| | - John S Satterlee
- Division of Basic Neurobiology and Behavioral Research, Genetics and Molecular Neurobiology Research Branch, National Institute on Drug Abuse/National Institutes of Health (NIH), 6001 Executive Boulevard, Bethesda, MD 20850, USA
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Matzke AJM, Matzke M. Membrane "potential-omics": toward voltage imaging at the cell population level in roots of living plants. FRONTIERS IN PLANT SCIENCE 2013; 4:311. [PMID: 23964285 PMCID: PMC3734365 DOI: 10.3389/fpls.2013.00311] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Accepted: 07/24/2013] [Indexed: 05/18/2023]
Abstract
Genetically encoded voltage-sensitive fluorescent proteins (VSFPs) are being used in neurobiology as non-invasive tools to study synchronous electrical activities in specific groups of nerve cells. Here we discuss our efforts to adapt this "light-based electrophysiology" for use in plant systems. We describe the production of transgenic plants engineered to express different versions of VSFPs that are targeted to the plasma membrane and internal membranes of root cells. The aim is to optically record concurrent changes in plasma membrane potential in populations of cells and at multiple membrane systems within single cells in response to various stimuli in living plants. Such coordinated electrical changes may globally orchestrate cell behavior to elicit successful reactions of the root as a whole to varying and unpredictable environments. Findings from membrane "potential-omics" can eventually be fused with data sets from other "omics" approaches to forge the integrated and comprehensive understanding that underpins the concept of systems biology.
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