201
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Barrett JM, Degenaar P, Sernagor E. Blockade of pathological retinal ganglion cell hyperactivity improves optogenetically evoked light responses in rd1 mice. Front Cell Neurosci 2015; 9:330. [PMID: 26379501 PMCID: PMC4548307 DOI: 10.3389/fncel.2015.00330] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 08/10/2015] [Indexed: 12/17/2022] Open
Abstract
Retinitis pigmentosa (RP) is a progressive retinal dystrophy that causes visual impairment and eventual blindness. Retinal prostheses are the best currently available vision-restoring treatment for RP, but only restore crude vision. One possible contributing factor to the poor quality of vision achieved with prosthetic devices is the pathological retinal ganglion cell (RGC) hyperactivity that occurs in photoreceptor dystrophic disorders. Gap junction blockade with meclofenamic acid (MFA) was recently shown to diminish RGC hyperactivity and improve the signal-to-noise ratio (SNR) of RGC responses to light flashes and electrical stimulation in the rd10 mouse model of RP. We sought to extend these results to spatiotemporally patterned optogenetic stimulation in the faster-degenerating rd1 model and compare the effectiveness of a number of drugs known to disrupt rd1 hyperactivity. We crossed rd1 mice with a transgenic mouse line expressing the light-sensitive cation channel channelrhodopsin2 (ChR2) in RGCs, allowing them to be stimulated directly using high-intensity blue light. We used 60-channel ITO multielectrode arrays to record ChR2-mediated RGC responses from wholemount, ex-vivo retinas to full-field and patterned stimuli before and after application of MFA, 18-β-glycyrrhetinic acid (18BGA, another gap junction blocker) or flupirtine (Flu, a Kv7 potassium channel opener). All three drugs decreased spontaneous RGC firing, but 18BGA and Flu also decreased the sensitivity of RGCs to optogenetic stimulation. Nevertheless, all three drugs improved the SNR of ChR2-mediated responses. MFA also made it easier to discern motion direction of a moving bar from RGC population responses. Our results support the hypothesis that reduction of pathological RGC spontaneous activity characteristic in retinal degenerative disorders may improve the quality of visual responses in retinal prostheses and they provide insights into how best to achieve this for optogenetic prostheses.
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Affiliation(s)
- John M Barrett
- Faculty of Medical Sciences, Institute of Neuroscience, Newcastle University Newcastle-upon-Tyne, UK
| | - Patrick Degenaar
- Faculty of Science, Agriculture and Engineering, School of Electrical and Electronic Engineering, Newcastle University Newcastle-upon-Tyne, UK
| | - Evelyne Sernagor
- Faculty of Medical Sciences, Institute of Neuroscience, Newcastle University Newcastle-upon-Tyne, UK
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202
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Cehajic-Kapetanovic J, Eleftheriou C, Allen AE, Milosavljevic N, Pienaar A, Bedford R, Davis KE, Bishop PN, Lucas RJ. Restoration of Vision with Ectopic Expression of Human Rod Opsin. Curr Biol 2015; 25:2111-22. [PMID: 26234216 PMCID: PMC4540256 DOI: 10.1016/j.cub.2015.07.029] [Citation(s) in RCA: 121] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 06/19/2015] [Accepted: 07/10/2015] [Indexed: 11/10/2022]
Abstract
Many retinal dystrophies result in photoreceptor loss, but the inner retinal neurons can survive, making them potentially amenable to emerging optogenetic therapies. Here, we show that ectopically expressed human rod opsin, driven by either a non-selective or ON-bipolar cell-specific promoter, can function outside native photoreceptors and restore visual function in a mouse model of advanced retinal degeneration. Electrophysiological recordings from retinal explants and the visual thalamus revealed changes in firing (increases and decreases) induced by simple light pulses, luminance increases, and naturalistic movies in treated mice. These responses could be elicited at light intensities within the physiological range and substantially below those required by other optogenetic strategies. Mice with rod opsin expression driven by the ON-bipolar specific promoter displayed behavioral responses to increases in luminance, flicker, coarse spatial patterns, and elements of a natural movie at levels of contrast and illuminance (≈50–100 lux) typical of natural indoor environments. These data reveal that virally mediated ectopic expression of human rod opsin can restore vision under natural viewing conditions and at moderate light intensities. Given the inherent advantages in employing a human protein, the simplicity of this intervention, and the quality of vision restored, we suggest that rod opsin merits consideration as an optogenetic actuator for treating patients with advanced retinal degeneration. Ectopic human rod opsin restores visual functions in advanced retinal degeneration Rod opsin has greater sensitivity than current optogenetic strategies Rod opsin-treated animals respond to spatial stimuli, flicker, and natural scenes As a human protein ordinarily found in retinal tissue, barriers to clinic are minimized
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Affiliation(s)
- Jasmina Cehajic-Kapetanovic
- Centre for Ophthalmology and Vision Sciences, Institute of Human Development, University of Manchester, Manchester M13 9PT, UK; Manchester Royal Eye Hospital, CMFT, Manchester Academic Health Sciences Centre, Manchester M13 9NT, UK
| | - Cyril Eleftheriou
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK
| | - Annette E Allen
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK
| | - Nina Milosavljevic
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK
| | - Abigail Pienaar
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK
| | - Robert Bedford
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK
| | - Katherine E Davis
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK
| | - Paul N Bishop
- Centre for Ophthalmology and Vision Sciences, Institute of Human Development, University of Manchester, Manchester M13 9PT, UK; Manchester Royal Eye Hospital, CMFT, Manchester Academic Health Sciences Centre, Manchester M13 9NT, UK.
| | - Robert J Lucas
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK.
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203
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Psychophysical testing in rodent models of glaucomatous optic neuropathy. Exp Eye Res 2015; 141:154-63. [PMID: 26144667 DOI: 10.1016/j.exer.2015.06.025] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Revised: 06/08/2015] [Accepted: 06/29/2015] [Indexed: 12/14/2022]
Abstract
Processing of visual information begins in the retina, with photoreceptors converting light stimuli into neural signals. Ultimately, signals are transmitted to the brain through signaling networks formed by interneurons, namely bipolar, horizontal and amacrine cells providing input to retinal ganglion cells (RGCs), which form the optic nerve with their axons. As part of the chronic nature of glaucomatous optic neuropathy, the increasing and irreversible damage and ultimately loss of neurons, RGCs in particular, occurs following progressive damage to the optic nerve head (ONH), eventually resulting in visual impairment and visual field loss. There are two behavioral assays that are typically used to assess visual deficits in glaucoma rodent models, the visual water task and the optokinetic drum. The visual water task can assess an animal's ability to distinguish grating patterns that are associated with an escape from water. The optokinetic drum relies on the optomotor response, a reflex turning of the head and neck in the direction of the visual stimuli, which usually consists of rotating black and white gratings. This reflex is a physiological response critical for keeping the image stable on the retina. Driven initially by the neuronal input from direction-selective RGCs, this reflex is comprised of a number of critical sensory and motor elements. In the presence of repeatable and defined stimuli, this reflex is extremely well suited to analyze subtle changes in the circuitry and performance of retinal neurons. Increasing the cycles of these alternating gratings per degree, or gradually reducing the contrast of the visual stimuli, threshold levels can be determined at which the animal is no longer tracking the stimuli, and thereby visual function of the animal can be determined non-invasively. Integrating these assays into an array of outcome measures that determine multiple aspects of visual function is a central goal in vision research and can be realized, for example, by the combination of measuring optomotor reflex function with electroretinograms (ERGs) and optical coherence tomography (OCT) of the retina. These structure-function correlations in vivo are urgently needed to identify disease mechanisms as potential new targets for drug development. Such a combination of the experimental assessment of the optokinetic reflex (OKR) or optomotor response (OMR) with other measures of retinal structure and function is especially valuable for research on GON. The chronic progression of the disease is characterized by a gradual decrease in function accompanied by a concomitant increase in structural damage to the retina, therefore the assessment of subtle changes is key to determining the success of novel intervention strategies.
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204
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Hovhannisyan A, Benkner B, Biesemeier A, Schraermeyer U, Kukley M, Münch TA. Effects of the jimpy mutation on mouse retinal structure and function. J Comp Neurol 2015; 523:2788-806. [PMID: 26011242 DOI: 10.1002/cne.23818] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 10/30/2014] [Accepted: 05/19/2015] [Indexed: 12/15/2022]
Abstract
The Jimpy mutant mouse has a point mutation in the proteolipid protein gene (plp1). The resulting misfolding of the protein leads to oligodendrocyte death, myelin destruction, and failure to produce adequately myelinated axons in the central nervous system (CNS). It is not known how the absence of normal myelination during development influences neural function. We characterized the Jimpy mouse retina to find out whether lack of myelination in the optic nerve during development has an effect on normal functioning and morphology of the retina. Optokinetic reflex measurements showed that Jimpy mice had, in general, a functional visual system. Both PLP1 antibody staining and reverse transcriptase-polymerase chain reaction for plp1 mRNA showed that plp1 is not expressed in the wild-type retina. However, in the optic nerve, plp1 is normally expressed, and consequently, in Jimpy mutant mice, myelination of axons in the optic nerve was mostly absent. Nevertheless, neither axon count nor axon ultrastructure in the optic nerve was affected. Physiological recordings of ganglion cell activity using microelectrode arrays revealed a decrease of stimulus-evoked activity at mesopic light levels. Morphological analysis of the retina did not show any significant differences in the gross morphology, such as thickness of retinal layers or cell number in the inner and outer nuclear layer. The cell bodies in the inner nuclear layer, however, were larger in the peripheral retina of Jimpy mutant mice. Antibody labeling against cell type-specific markers showed that the number of rod bipolar and horizontal cells was increased in Jimpy mice. In conclusion, whereas the Jimpy mutation has dramatic effects on the myelination of retinal ganglion cell axons, it has moderate effects on retinal morphology and function.
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Affiliation(s)
- Anahit Hovhannisyan
- Retinal Circuits and Optogenetics, Center for Integrative Neuroscience, University of Tübingen, 72076, Tübingen, Germany.,Neuron Glia Interactions, Center for Integrative Neuroscience, University of Tübingen, 72076, Tübingen, Germany
| | - Boris Benkner
- Retinal Circuits and Optogenetics, Center for Integrative Neuroscience, University of Tübingen, 72076, Tübingen, Germany
| | - Antje Biesemeier
- Section of Experimental Vitreoretinal Surgery, Center for Ophthalmology, 72076, Tübingen, Germany
| | - Ulrich Schraermeyer
- Section of Experimental Vitreoretinal Surgery, Center for Ophthalmology, 72076, Tübingen, Germany
| | - Maria Kukley
- Neuron Glia Interactions, Center for Integrative Neuroscience, University of Tübingen, 72076, Tübingen, Germany
| | - Thomas A Münch
- Retinal Circuits and Optogenetics, Center for Integrative Neuroscience, University of Tübingen, 72076, Tübingen, Germany
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205
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Satpathy S, Batabyal S, Dhakal KR, Lin J, Kim YT, Mohanty SK. Broad spectral excitation of opsin for enhanced stimulation of cells. OPTICS LETTERS 2015; 40:2465-2468. [PMID: 26030533 DOI: 10.1364/ol.40.002465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Optical stimulation of cells expressing light-sensitive proteins (opsins) has allowed targeted activation with cellular specificity. However, since narrow-band light has been used for excitation of these optogenetic probes, only active stimulation strategies are being attempted for clinical applications such as restoration of vision. Here, we report use of broad spectral excitation (white light) for optogenetic stimulation of opsin-sensitized cells. We found that ReaChR is optimally excited with white light offering significantly higher photocurrents compared to spectrally filtered narrow-band light stimulation. Our findings open up the possibility of passive stimulation strategy by use of natural sunlight for retinal stimulation, which could have benefits for ambient light stimulated vision restoration.
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206
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Cronin T, Vandenberghe LH, Hantz P, Juttner J, Reimann A, Kacsó AE, Huckfeldt RM, Busskamp V, Kohler H, Lagali PS, Roska B, Bennett J. Efficient transduction and optogenetic stimulation of retinal bipolar cells by a synthetic adeno-associated virus capsid and promoter. EMBO Mol Med 2015; 6:1175-90. [PMID: 25092770 PMCID: PMC4197864 DOI: 10.15252/emmm.201404077] [Citation(s) in RCA: 124] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In this report, we describe the development of a modified adeno-associated virus (AAV) capsid and promoter for transduction of retinal ON-bipolar cells. The bipolar cells, which are post-synaptic to the photoreceptors, are important retinal targets for both basic and preclinical research. In particular, a therapeutic strategy under investigation for advanced forms of blindness involves using optogenetic molecules to render ON-bipolar cells light-sensitive. Currently, delivery of adequate levels of gene expression is a limiting step for this approach. The synthetic AAV capsid and promoter described here achieves high level of optogenetic transgene expression in ON-bipolar cells. This evokes high-frequency (∼100 Hz) spiking responses in ganglion cells of previously blind, rd1, mice. Our vector is a promising vehicle for further development toward potential clinical use.
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Affiliation(s)
- Therese Cronin
- Center for Advanced Retinal and Ophthalmic Therapeutics, F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, USA Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Luk H Vandenberghe
- Center for Advanced Retinal and Ophthalmic Therapeutics, F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, USA Schepens Eye Research Institute, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA, USA
| | - Péter Hantz
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Josephine Juttner
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Andreas Reimann
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | | | - Rachel M Huckfeldt
- Center for Advanced Retinal and Ophthalmic Therapeutics, F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, USA
| | - Volker Busskamp
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland Genetics Department, Harvard Medical School, Boston, MA, USA
| | - Hubertus Kohler
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Pamela S Lagali
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - Botond Roska
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Jean Bennett
- Center for Advanced Retinal and Ophthalmic Therapeutics, F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, USA
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207
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Vandecasteele M, Senova YS, Palfi S, Dugué GP. Potentiel thérapeutique de la neuromodulation optogénétique. Med Sci (Paris) 2015; 31:404-16. [DOI: 10.1051/medsci/20153104015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
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208
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Restoring the ON Switch in Blind Retinas: Opto-mGluR6, a Next-Generation, Cell-Tailored Optogenetic Tool. PLoS Biol 2015; 13:e1002143. [PMID: 25950461 PMCID: PMC4423780 DOI: 10.1371/journal.pbio.1002143] [Citation(s) in RCA: 144] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Accepted: 03/30/2015] [Indexed: 12/27/2022] Open
Abstract
Photoreceptor degeneration is one of the most prevalent causes of blindness. Despite photoreceptor loss, the inner retina and central visual pathways remain intact over an extended time period, which has led to creative optogenetic approaches to restore light sensitivity in the surviving inner retina. The major drawbacks of all optogenetic tools recently developed and tested in mouse models are their low light sensitivity and lack of physiological compatibility. Here we introduce a next-generation optogenetic tool, Opto-mGluR6, designed for retinal ON-bipolar cells, which overcomes these limitations. We show that Opto-mGluR6, a chimeric protein consisting of the intracellular domains of the ON-bipolar cell-specific metabotropic glutamate receptor mGluR6 and the light-sensing domains of melanopsin, reliably recovers vision at the retinal, cortical, and behavioral levels under moderate daylight illumination.
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209
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Abstract
PURPOSE OF REVIEW In this review, we will discuss the recent developments in optogenetics and their potential applications in ophthalmology to restore vision in retinal degenerative diseases. RECENT FINDINGS In recent years, we have seen major advances in the field of optogenetics, providing us with novel opsins for potential applications in the retina. Microbial opsins with improved light sensitivity and red-shifted action spectra allow optogenetic stimulation at light levels well below the safety threshold in the human eye. In parallel, remarkable success in the development of highly efficient viral vectors for ocular gene therapy led to new strategies of using these novel optogenetic tools for vision restoration. SUMMARY These recent findings show that novel optogenetic tools and viral vectors for ocular gene delivery are now available providing many opportunities to develop potential optogenetic strategies for vision restoration.
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Affiliation(s)
- Jens Duebel
- Institut de la Vision
Université Pierre et Marie Curie - Paris 6 - UM80Institut National de la Santé et de la Recherche Médicale - U968Centre National de la Recherche Scientifique - UMR721017 Rue Moreau, 75012 Paris
| | - Katia Marazova
- Institut de la Vision
Université Pierre et Marie Curie - Paris 6 - UM80Institut National de la Santé et de la Recherche Médicale - U968Centre National de la Recherche Scientifique - UMR721017 Rue Moreau, 75012 Paris
| | - José-Alain Sahel
- Institut de la Vision
Université Pierre et Marie Curie - Paris 6 - UM80Institut National de la Santé et de la Recherche Médicale - U968Centre National de la Recherche Scientifique - UMR721017 Rue Moreau, 75012 Paris
- Fondation Ophtalmologique Rothschild
75019 Paris
- Centre Hospitalier National d’Ophtalmologie des Quinze-Vingts
INSERM-DHOS CIC 1423 -
- Institute of Ophthalmology [London]
University College of London [London] - London EC1V 9EL
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210
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Fine I, Cepko CL, Landy MS. Vision research special issue: Sight restoration: Prosthetics, optogenetics and gene therapy. Vision Res 2015; 111:115-23. [PMID: 25937376 DOI: 10.1016/j.visres.2015.04.012] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Ione Fine
- Department of Psychology, University of Washington, Seattle, WA, USA
| | - Connie L Cepko
- Departments of Genetics and Ophthalmology, Howard Hughes Medical Institute, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
| | - Michael S Landy
- Department of Psychology and Center for Neural Science, New York University, New York, NY, USA
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211
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Optogenetics applications for treating spinal cord injury. Asian Spine J 2015; 9:299-305. [PMID: 25901246 PMCID: PMC4404549 DOI: 10.4184/asj.2015.9.2.299] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Revised: 11/08/2014] [Accepted: 11/16/2014] [Indexed: 12/28/2022] Open
Abstract
Cases of spinal cord injury (SCI) are increasing all over the world; and in USA alone, there are 273,000 patients, which not only leads to morbidity and mortality but also results in a great economic burden. Many approaches are being used at the pre-clinical and clinical level to treat SCI including therapeutic agents, surgical decompression, stem cell therapy etc. Recently, a new approach called optogenetics has emerged in which light sensitive proteins are used to switch neurons on and off, and this approach has great potential to be used as therapy due to its specificity and rapid response in milliseconds. Few animal studies have been performed so far in which the respiratory and bladder function of rats was restored through the use of optogenetics. On the basis of promising results obtained, in the future, this approach can prove to be a valuable tool to treat patients with SCI.
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212
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Lee KA, Lee SS, Kim SY, Choi AR, Lee JH, Jung KH. Mistic-fused expression of algal rhodopsins in Escherichia coli and its photochemical properties. Biochim Biophys Acta Gen Subj 2015; 1850:1694-703. [PMID: 25869488 DOI: 10.1016/j.bbagen.2015.04.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 03/10/2015] [Accepted: 04/03/2015] [Indexed: 01/29/2023]
Abstract
BACKGROUND Since algal rhodopsins, the eukaryotic seven-transmembrane proteins, are generally difficult to express in Escherichia coli, eukaryotic cells have been used for heterologous expression. Mistic, a membrane-associated protein that was originally discovered in Bacillus subtilis, has been shown to improve the expression levels of many foreign integral membrane proteins in E. coli when used as a fusion partner linked to the N-terminus of cargo proteins. METHODS Here, we expressed two algal rhodopsins with N- and C-terminal Mistic domains in E. coli-Acetabularia rhodopsin I (ARI) and Chlamydomonas sensory rhodopsin B (CSRB, channel rhodopsin 2). UV/VIS spectroscopy, pH titration of proton acceptor residue, laser-induced photolysis and electrophysiological measurement were used for investigating important residues in proton transport and spectroscopic characters of the proteins. RESULTS Protein yield of two algal rhodopsins was enhanced, obtaining 0.12mg of Mistic-ARI and 0.04mg of Mistic-CSRB per liter of culture. Spheroplast expression Mistic-ARI had outward proton-pumping activity, indicating protein functionality. Asp89 of ARI changed its protonation state by light absorption, and Asp100 was important for O(600) formation. Electrophysiology revealed that both residues took part in proton transport. The spectroscopic analyses of Mistic-CSRB revealed its characteristics. CONCLUSIONS Fusion to the membrane-integrating protein Mistic can enhance overexpression of eukaryotic type I rhodopsins in E. coli. GENERAL SIGNIFICANCE These findings indicate that Mistic fusion and E. coli expression method could be an effective, low cost technique for studying eukaryotic membrane proteins. This may have useful implications, for example, in studying structural characteristics and optogenetics for rhodopsins.
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Affiliation(s)
- Keon Ah Lee
- Department of Life Science and Interdisciplinary Program of Integrated Biotechnology, Sogang University, Shinsu-Dong 1, Mapo-Gu, Seoul 121-742, Republic of Korea
| | - Sang-Soo Lee
- Department of Life Science and Interdisciplinary Program of Integrated Biotechnology, Sogang University, Shinsu-Dong 1, Mapo-Gu, Seoul 121-742, Republic of Korea
| | - So Young Kim
- Department of Life Science and Interdisciplinary Program of Integrated Biotechnology, Sogang University, Shinsu-Dong 1, Mapo-Gu, Seoul 121-742, Republic of Korea
| | - Ah Reum Choi
- Department of Life Science and Interdisciplinary Program of Integrated Biotechnology, Sogang University, Shinsu-Dong 1, Mapo-Gu, Seoul 121-742, Republic of Korea
| | - Jung-Ha Lee
- Department of Life Science and Interdisciplinary Program of Integrated Biotechnology, Sogang University, Shinsu-Dong 1, Mapo-Gu, Seoul 121-742, Republic of Korea
| | - Kwang-Hwan Jung
- Department of Life Science and Interdisciplinary Program of Integrated Biotechnology, Sogang University, Shinsu-Dong 1, Mapo-Gu, Seoul 121-742, Republic of Korea.
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213
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Optogenetic control of insulin secretion by pancreatic β-cells in vitro and in vivo. Gene Ther 2015; 22:553-9. [DOI: 10.1038/gt.2015.23] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Revised: 02/12/2015] [Accepted: 02/19/2015] [Indexed: 12/12/2022]
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214
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Ramachandran PS, Song JY, Bennett J. Exploiting metabolic and antioxidant pathways to maintain vision in blinding disease. J Clin Invest 2015; 125:1390-2. [PMID: 25798615 DOI: 10.1172/jci80821] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The use of gene therapy for blinding disease shows growing promise; however, due to an ever-expanding list of disease-causing genes and mutations, the identification of a generic gene-based treatment is urgently needed. In many forms of degenerative retinal disease, there may be a window of opportunity to preserve daylight vision, as the cone photoreceptors degenerate more slowly than do the rods. In this issue of the JCI, Venkatesh et al. and Xiong et al. exploit two different pathways to promote cone cell survival and preserve vision in murine retinal degeneration models. These studies provide hope for developing a universal reagent to treat many different blinding disorders.
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215
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Photosensitivity of neurons enabled by cell-targeted gold nanoparticles. Neuron 2015; 86:207-17. [PMID: 25772189 DOI: 10.1016/j.neuron.2015.02.033] [Citation(s) in RCA: 233] [Impact Index Per Article: 25.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Revised: 01/18/2015] [Accepted: 02/14/2015] [Indexed: 01/05/2023]
Abstract
Unmodified neurons can be directly stimulated with light to produce action potentials, but such techniques have lacked localization of the delivered light energy. Here we show that gold nanoparticles can be conjugated to high-avidity ligands for a variety of cellular targets. Once bound to a neuron, these particles transduce millisecond pulses of light into heat, which changes membrane capacitance, depolarizing the cell and eliciting action potentials. Compared to non-functionalized nanoparticles, ligand-conjugated nanoparticles highly resist convective washout and enable photothermal stimulation with lower delivered energy and resulting temperature increase. Ligands targeting three different membrane proteins were tested; all showed similar activity and washout resistance. This suggests that many types of ligands can be bound to nanoparticles, preserving ligand and nanoparticle function, and that many different cell phenotypes can be targeted by appropriate choice of ligand. The findings have applications as an alternative to optogenetics and potentially for therapies involving neuronal photostimulation.
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216
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Gu L, Uhelski ML, Anand S, Romero-Ortega M, Kim YT, Fuchs PN, Mohanty SK. Pain inhibition by optogenetic activation of specific anterior cingulate cortical neurons. PLoS One 2015; 10:e0117746. [PMID: 25714399 PMCID: PMC4340873 DOI: 10.1371/journal.pone.0117746] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2014] [Accepted: 12/31/2014] [Indexed: 01/22/2023] Open
Abstract
Cumulative evidence from both humans and animals suggests that the anterior cingulate cortex (ACC) is important for pain-related perception, and thus a likely target for pain relief therapy. However, use of existing electrode based ACC stimulation has not significantly reduced pain, at least in part due to the lack of specificity and likely co-activation of both excitatory and inhibitory neurons. Herein, we report a dramatic reduction of pain behavior in transgenic mice by optogenetic stimulation of the inhibitory neural circuitry of the ACC expressing channelrhodopsin-2. Electrophysiological measurements confirmed that stimulation of ACC inhibitory neurons is associated with decreased neural activity in the ACC. Further, a distinct optogenetic stimulation intensity and frequency-dependent inhibition of spiking activity in the ACC was observed. Moreover, we confirmed specific electrophysiological responses from different neuronal units in the thalamus, in response to particular types of painful stimuli (i,e., formalin injection, pinch), which we found to be modulated by optogenetic control of the ACC inhibitory neurons. These results underscore the inhibition of the ACC as a clinical alternative in inhibiting chronic pain, and leads to a better understanding of the pain processing circuitry of the cingulate cortex.
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Affiliation(s)
- Ling Gu
- Biophysics and Physiology Group, Department of Physics, University of Texas at Arlington, Arlington, TX-76019, United States of America
| | - Megan L. Uhelski
- Department of Psychology, University of Texas at Arlington, Arlington, TX-76019, United States of America
| | - Sanjay Anand
- Department of Bioengineering, University of Texas at Arlington, Arlington, TX-76019, United States of America
| | - Mario Romero-Ortega
- Department of Bioengineering, University of Texas at Arlington, Arlington, TX-76019, United States of America
| | - Young-tae Kim
- Department of Bioengineering, University of Texas at Arlington, Arlington, TX-76019, United States of America
| | - Perry N. Fuchs
- Departments of Psychology and Biology, University of Texas at Arlington, Arlington, TX-76019, United States of America
| | - Samarendra K. Mohanty
- Biophysics and Physiology Group, Department of Physics, University of Texas at Arlington, Arlington, TX-76019, United States of America
- * E-mail:
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217
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Tochitsky I, Kramer RH. Optopharmacological tools for restoring visual function in degenerative retinal diseases. Curr Opin Neurobiol 2015; 34:74-8. [PMID: 25706312 DOI: 10.1016/j.conb.2015.01.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Revised: 01/26/2015] [Accepted: 01/28/2015] [Indexed: 11/17/2022]
Abstract
Retinitis pigmentosa (RP) and age-related macular degeneration (AMD) are progressive retinal diseases that result from the death of rod and cone photoreceptors, ultimately leading to blindness. The only currently approved vision restoration treatment employs an implanted retinal 'chip' as a prosthetic device to electrically stimulate retinal neurons that survive after the photoreceptors are gone, thereby restoring light-driven neural signaling to the brain. Alternative strategies have been proposed, which would utilize optogenetic or optopharmacological tools to enable direct optical stimulation of surviving retinal neurons. Here, we review the latest studies evaluating the feasibility of these molecular tools as potential therapeutics for restoring visual function in human blinding disease.
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Affiliation(s)
- Ivan Tochitsky
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Richard H Kramer
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA.
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218
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Van Gelder RN. Photochemical approaches to vision restoration. Vision Res 2015; 111:134-41. [PMID: 25680758 DOI: 10.1016/j.visres.2015.02.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Revised: 01/06/2015] [Accepted: 02/02/2015] [Indexed: 11/18/2022]
Abstract
Photoswitches are traditional pharmacologic agonists, antagonists, or channel blockers that are covalently modified with an azobenzene derivative. Azobenzene undergoes wavelength-dependent isomerization between cis and trans conformation. For some photoswitches, only one of these configurations is biologically active, resulting in light-dependent activation or inhibition of function. Photoswitches that feature a quaternary ammonium coupled to the azobenzene moiety cause light-dependent neuronal depolarization due to blockage of voltage-gated potassium channels. Two photoswitch strategies have been pursued. In the one-component strategy, the photoswitch is applied to native receptors; in the two-component strategy, the photoswitch is combined with virally-mediated expression of a genetically modified receptor, to which the photoswitch may covalently bind. The former approach is simpler but the latter allows precise anatomic targeting of photoswitch activity. Acrylamide-azobenzene-quaternary ammonium (AAQ) is the prototypical first-generation one-component photoswitch. When applied to retinas with outer retinal degeneration, ganglion cell firing occurs in response to blue light, and is abrogated by green light. In vivo, AAQ restored pupillary light responses and behavioral light responses in blind animals. DENAQ is a prototypical second generation one-component photoswitch. It features spontaneous thermal relaxation so cell firing ceases in dark, and features a red-shifted activation spectrum. Interestingly, DENAQ only photoswitches in retinas with outer retinal degeneration. MAG is a photoswitched glutamate analog which covalently binds to a modified ionotropic glutamate receptor, LiGluR. When applied together, MAG and LiGluR also rescue physiologic and behavioral light responses in blind mice. Together, photoswitch compounds offer a potentially useful approach to restoration of vision in outer retinal degeneration.
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Affiliation(s)
- Russell N Van Gelder
- Department of Ophthalmology, University of Washington School of Medicine, United States; Department of Pathology, University of Washington School of Medicine, United States; Department of Biological Structure, University of Washington School of Medicine, United States.
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219
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Henriksen BS, Marc RE, Bernstein PS. Optogenetics for retinal disorders. J Ophthalmic Vis Res 2015; 9:374-82. [PMID: 25667740 PMCID: PMC4307663 DOI: 10.4103/2008-322x.143379] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2014] [Accepted: 05/10/2014] [Indexed: 12/26/2022] Open
Abstract
Optogenetics is the use of genetic methods combined with optical technology to achieve gain or loss of function within neuronal circuits. The field of optogenetics has been rapidly expanding in efforts to restore visual function to blinding diseases such as retinitis pigmentosa (RP). Most work in the field includes a group of light-sensitive retinaldehyde-binding proteins known as opsins. Opsins couple photon absorption to molecular signaling chains that control cellular ion currents. Targeting of opsin genes to surviving retinal cells is fundamental to the success of optogenetic therapy. Viral delivery, primarily adeno-associated virus, using intravitreal injection for inner retinal cells and subretinal injection for outer retinal cells, has proven successful in many models. Challenges in bioengineering remain for optogenetics including relative insensitivity of opsins to physiologic light levels of stimulation and difficulty with viral delivery in primate models. However, targeting optogenetic therapy may present an even greater challenge. Neural and glial remodeling seen in advanced stages of RP result in reorganization of remaining neural retina, and optogenetic therapy may not yield functional results. Remodeling also poses a challenge to the selection of cellular targets, with bipolar, amacrine and ganglion cells all playing distinct physiologic roles, and affected by remodeling differently. Although optogenetics has drawn closer to clinical utility, advances in opsin engineering, therapeutic targeting and ultimately in molecular inhibition of remodeling will play critical roles in the continued clinical advancement of optogenetic therapy.
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Affiliation(s)
- Bradley S Henriksen
- Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - Robert E Marc
- Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - Paul S Bernstein
- Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah School of Medicine, Salt Lake City, Utah, USA
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221
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Bouchie A, Allison M, Webb S, DeFrancesco L. Nature Biotechnology's academic spinouts of 2013. Nat Biotechnol 2015; 32:229-38. [PMID: 24727773 DOI: 10.1038/nbt.2846] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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222
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Abstract
We describe recent progress toward defining neuronal cell types in the mouse retina and attempt to extract lessons that may be generally useful in the mammalian brain. Achieving a comprehensive catalog of retinal cell types now appears within reach, because researchers have achieved consensus concerning two fundamental challenges. The first is accuracy-defining pure cell types rather than settling for neuronal classes that are mixtures of types. The second is completeness-developing methods guaranteed to eventually identify all cell types, as well as criteria for determining when all types have been found. Case studies illustrate how these two challenges are handled by combining state-of-the-art molecular, anatomical, and physiological techniques. Progress is also being made in observing and modeling connectivity between cell types. Scaling up to larger brain regions, such as the cortex, will require not only technical advances but also careful consideration of the challenges of accuracy and completeness.
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223
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Abstract
Optogenetics is an innovative technique for optical control of cells. This field has exploded over the past decade or so and has given rise to great advances in neuroscience. A variety of applications both from the basic and applied research have emerged, turning the early ideas into a powerful paradigm for cell biology, neuroscience and medical research. This review aims at highlighting the basic concepts that are essential for a comprehensive understanding of optogenetics and some important biological/biomedical applications. Further, emphasis is placed on advancement in optogenetics-associated light-based methods for controlling gene expression, spatially-controlled optogenetic stimulation and detection of cellular activities.
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Affiliation(s)
- Samarendra K. Mohanty
- Biophysics and Physiology Group, Department of Physics, The University of Texas at Arlington, USA. Tel. 817-272-1177, Fax: +1-817-272-3637
| | - Vasudevan Lakshminarayananan
- School of Optometry and Vision Science, Departments of Physics and Electrical and Computer Engineering, University of Waterloo, Waterloo, ON Canada. Department of Physics, Unviersity of Michigan, Ann Arbor, USA
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224
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Chapter 7- Restoring Vision to the Blind: Advancements in Vision Aids for the Visually Impaired. Transl Vis Sci Technol 2014; 3:9. [PMID: 25653893 DOI: 10.1167/tvst.3.7.9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 10/27/2014] [Indexed: 11/24/2022] Open
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225
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Mutter M, Swietek N, Münch TA. Salvaging ruins: reverting blind retinas into functional visual sensors. Methods Mol Biol 2014; 1148:149-60. [PMID: 24718800 DOI: 10.1007/978-1-4939-0470-9_10] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Blindness is one of the most devastating conditions affecting the quality of life. Hereditary degenerative diseases, such as retinitis pigmentosa, are characterized by the progressive loss of photoreceptors, leading to complete blindness. No treatment is known, the current state-of-the-art of restoring vision are implanted electrode arrays. As a recently discovered alternative, optical neuromodulators, such as channelrhodopsin, allow new strategies for treating these diseases by imparting light-sensitivity onto the remaining retinal neurons after photoreceptor cell death. Retinal degeneration is a heterogeneous set of diseases with diverse secondary effects on the retinal circuitry. Successful treatment strategies have to take into account this diversity, as only the existing retinal hardware can serve as substrate for optogenetic intervention. The goal is to salvage the retinal ruins and to revert the leftover tissue into a functional visual sensor that operates as optimally as possible. Here, we discuss three different successful approaches that have been applied to degenerated mouse retina.
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Affiliation(s)
- Marion Mutter
- Centre for Integrative Neuroscience, Bernstein Center for Computational Biology, University Tübingen, Otfried-Müller-Str. 25, Tübingen, Germany
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226
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Retinal output changes qualitatively with every change in ambient illuminance. Nat Neurosci 2014; 18:66-74. [PMID: 25485757 PMCID: PMC4338531 DOI: 10.1038/nn.3891] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Accepted: 10/28/2014] [Indexed: 12/20/2022]
Abstract
The collective activity pattern of retinal ganglion cells, the retinal code, underlies higher visual processing. How does the ambient illuminance of the visual scene influence this retinal output? We recorded from isolated mouse and pig retina and from mouse dLGN in-vivo at up to seven ambient light levels covering the scotopic to photopic regimes. Across each luminance transition, the majority of ganglion cells exhibited qualitative response changes, while maintaining stable responses within each luminance. Strikingly, we commonly observed the appearance and disappearance of ON responses in OFF cells and vice versa. Such qualitative response changes occurred for a variety of stimuli, including full-field and localized contrast steps, and naturalistic movies. Our results suggest that the retinal code is not fixed but varies with every change of ambient luminance. This finding raises new questions about signal processing within the retina and has intriguing implications for visual processing in higher brain areas.
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227
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Restoration of visual function by expression of a light-gated mammalian ion channel in retinal ganglion cells or ON-bipolar cells. Proc Natl Acad Sci U S A 2014; 111:E5574-83. [PMID: 25489083 DOI: 10.1073/pnas.1414162111] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Most inherited forms of blindness are caused by mutations that lead to photoreceptor cell death but spare second- and third-order retinal neurons. Expression of the light-gated excitatory mammalian ion channel light-gated ionotropic glutamate receptor (LiGluR) in retinal ganglion cells (RGCs) of the retina degeneration (rd1) mouse model of blindness was previously shown to restore some visual functions when stimulated by UV light. Here, we report restored retinal function in visible light in rodent and canine models of blindness through the use of a second-generation photoswitch for LiGluR, maleimide-azobenzene-glutamate 0 with peak efficiency at 460 nm (MAG0(460)). In the blind rd1 mouse, multielectrode array recordings of retinal explants revealed robust and uniform light-evoked firing when LiGluR-MAG0(460) was targeted to RGCs and robust but diverse activity patterns in RGCs when LiGluR-MAG0(460) was targeted to ON-bipolar cells (ON-BCs). LiGluR-MAG0(460) in either RGCs or ON-BCs of the rd1 mouse reinstated innate light-avoidance behavior and enabled mice to distinguish between different temporal patterns of light in an associative learning task. In the rod-cone dystrophy dog model of blindness, LiGluR-MAG0(460) in RGCs restored robust light responses to retinal explants and intravitreal delivery of LiGluR and MAG0(460) was well tolerated in vivo. The results in both large and small animal models of photoreceptor degeneration provide a path to clinical translation.
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228
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Chapter 2 - Restoring Vision to the Blind: Optogenetics. Transl Vis Sci Technol 2014; 3:4. [PMID: 25653888 PMCID: PMC4314991 DOI: 10.1167/tvst.3.7.4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 10/27/2014] [Indexed: 01/07/2023] Open
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229
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Bareket L, Waiskopf N, Rand D, Lubin G, David-Pur M, Ben-Dov J, Roy S, Eleftheriou C, Sernagor E, Cheshnovsky O, Banin U, Hanein Y. Semiconductor nanorod-carbon nanotube biomimetic films for wire-free photostimulation of blind retinas. NANO LETTERS 2014; 14:6685-92. [PMID: 25350365 PMCID: PMC4367200 DOI: 10.1021/nl5034304] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2014] [Revised: 10/25/2014] [Indexed: 05/22/2023]
Abstract
We report the development of a semiconductor nanorod-carbon nanotube based platform for wire-free, light induced retina stimulation. A plasma polymerized acrylic acid midlayer was used to achieve covalent conjugation of semiconductor nanorods directly onto neuro-adhesive, three-dimensional carbon nanotube surfaces. Photocurrent, photovoltage, and fluorescence lifetime measurements validate efficient charge transfer between the nanorods and the carbon nanotube films. Successful stimulation of a light-insensitive chick retina suggests the potential use of this novel platform in future artificial retina applications.
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Affiliation(s)
- Lilach Bareket
- School of Electrical Engineering, Tel Aviv University Center for Nanoscience
and Nanotechnology, and School of Chemistry, Tel
Aviv University, Tel Aviv 69978, Israel
| | - Nir Waiskopf
- Institute of Chemistry and Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - David Rand
- School of Electrical Engineering, Tel Aviv University Center for Nanoscience
and Nanotechnology, and School of Chemistry, Tel
Aviv University, Tel Aviv 69978, Israel
| | - Gur Lubin
- School of Electrical Engineering, Tel Aviv University Center for Nanoscience
and Nanotechnology, and School of Chemistry, Tel
Aviv University, Tel Aviv 69978, Israel
| | - Moshe David-Pur
- School of Electrical Engineering, Tel Aviv University Center for Nanoscience
and Nanotechnology, and School of Chemistry, Tel
Aviv University, Tel Aviv 69978, Israel
| | - Jacob Ben-Dov
- School of Electrical Engineering, Tel Aviv University Center for Nanoscience
and Nanotechnology, and School of Chemistry, Tel
Aviv University, Tel Aviv 69978, Israel
| | - Soumyendu Roy
- School of Electrical Engineering, Tel Aviv University Center for Nanoscience
and Nanotechnology, and School of Chemistry, Tel
Aviv University, Tel Aviv 69978, Israel
| | - Cyril Eleftheriou
- Institute
of Neuroscience, Faculty of Medical Sciences, Newcastle University, Newcastle
upon Tyne, NE2 4HH, United
Kingdom
| | - Evelyne Sernagor
- Institute
of Neuroscience, Faculty of Medical Sciences, Newcastle University, Newcastle
upon Tyne, NE2 4HH, United
Kingdom
| | - Ori Cheshnovsky
- School of Electrical Engineering, Tel Aviv University Center for Nanoscience
and Nanotechnology, and School of Chemistry, Tel
Aviv University, Tel Aviv 69978, Israel
| | - Uri Banin
- Institute of Chemistry and Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Yael Hanein
- School of Electrical Engineering, Tel Aviv University Center for Nanoscience
and Nanotechnology, and School of Chemistry, Tel
Aviv University, Tel Aviv 69978, Israel
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230
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Volkov V. Discovering electrophysiology in photobiology: A brief overview of several photobiological processes with an emphasis on electrophysiology. Commun Integr Biol 2014; 7:e28423. [PMID: 25328636 PMCID: PMC4183612 DOI: 10.4161/cib.28423] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Revised: 03/01/2014] [Accepted: 03/03/2014] [Indexed: 11/19/2022] Open
Abstract
The mini-review gives special attention to holistic approach and mechanisms of processes. The physical and chemical frames and background for visual perception and signaling are discussed. Perception of photons by retinal rod cells is described in more detail starting from photon absorption and culminating in ion currents. Dark noise and temperature-dependence of photocurrents in photoreceptor cells are analyzed. Perception of polarized light, its effects and informational importance are discussed based on underlying mechanisms and specialized morphological structures of biological organisms. Role of statistics of photons in photoreception is questioned. The review also pinpoints new and developing directions and raises questions for future research.
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Affiliation(s)
- Vadim Volkov
- Faculty of Life Sciences and Computing; London Metropolitan University; London, UK
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231
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Sahel JA, Marazova K, Audo I. Clinical characteristics and current therapies for inherited retinal degenerations. Cold Spring Harb Perspect Med 2014; 5:a017111. [PMID: 25324231 DOI: 10.1101/cshperspect.a017111] [Citation(s) in RCA: 145] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Inherited retinal degenerations (IRDs) encompass a large group of clinically and genetically heterogeneous diseases that affect approximately 1 in 3000 people (>2 million people worldwide) (Bessant DA, Ali RR, Bhattacharya SS. 2001. Molecular genetics and prospects for therapy of the inherited retinal dystrophies. Curr Opin Genet Dev 11: 307-316.). IRDs may be inherited as Mendelian traits or through mitochondrial DNA, and may affect the entire retina (e.g., rod-cone dystrophy, also known as retinitis pigmentosa, cone dystrophy, cone-rod dystrophy, choroideremia, Usher syndrome, and Bardet-Bidel syndrome) or be restricted to the macula (e.g., Stargardt disease, Best disease, and Sorsby fundus dystrophy), ultimately leading to blindness. IRDs are a major cause of severe vision loss, with profound impact on patients and society. Although IRDs remain untreatable today, significant progress toward therapeutic strategies for IRDs has marked the past two decades. This progress has been based on better understanding of the pathophysiological pathways of these diseases and on technological advances.
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Affiliation(s)
- José-Alain Sahel
- Institut de la Vision, Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Paris, F-75012, France INSERM, U968, Paris, F-75012, France CNRS, UMR 7210, Paris, F-75012, France Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, DHU ViewMaintain, INSERM-DHOS CIC 1423, Paris, F-75012, France Fondation Ophtalmologique Adolphe de Rothschild, Paris, F-75019, France Académie des Sciences-Institut de France, Paris, F-75006, France Institute of Ophthalmology-University College London, London EC1V 9EL, United Kingdom
| | - Katia Marazova
- Institut de la Vision, Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Paris, F-75012, France INSERM, U968, Paris, F-75012, France CNRS, UMR 7210, Paris, F-75012, France
| | - Isabelle Audo
- Institut de la Vision, Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Paris, F-75012, France INSERM, U968, Paris, F-75012, France CNRS, UMR 7210, Paris, F-75012, France Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, DHU ViewMaintain, INSERM-DHOS CIC 1423, Paris, F-75012, France Institute of Ophthalmology-University College London, London EC1V 9EL, United Kingdom
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232
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Marc R, Pfeiffer R, Jones B. Retinal prosthetics, optogenetics, and chemical photoswitches. ACS Chem Neurosci 2014; 5:895-901. [PMID: 25089879 PMCID: PMC4210130 DOI: 10.1021/cn5001233] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
![]()
Three
technologies have emerged as therapies to restore light sensing to
profoundly blind patients suffering from late-stage retinal degenerations:
(1) retinal prosthetics, (2) optogenetics, and (3) chemical photoswitches.
Prosthetics are the most mature and the only approach in clinical
practice. Prosthetic implants require complex surgical intervention
and provide only limited visual resolution but can potentially restore
navigational ability to many blind patients. Optogenetics uses viral
delivery of type 1 opsin genes from prokaryotes or eukaryote algae
to restore light responses in survivor neurons. Targeting and expression
remain major problems, but are potentially soluble. Importantly, optogenetics
could provide the ultimate in high-resolution vision due to the long
persistence of gene expression achieved in animal models. Nevertheless,
optogenetics remains challenging to implement in human eyes with large
volumes, complex disease progression, and physical barriers to viral
penetration. Now, a new generation of photochromic ligands or chemical
photoswitches (azobenzene-quaternary ammonium derivatives) can be
injected into a degenerated mouse eye and, in minutes to hours, activate
light responses in neurons. These photoswitches offer the potential
for rapidly and reversibly screening the vision restoration expected
in an individual patient. Chemical photoswitch variants that persist
in the cell membrane could make them a simple therapy of choice, with
resolution and sensitivity equivalent to optogenetics approaches.
A major complexity in treating retinal degenerations is retinal remodeling:
pathologic network rewiring, molecular reprogramming, and cell death
that compromise signaling in the surviving retina. Remodeling forces
a choice between upstream and downstream targeting, each engaging
different benefits and defects. Prosthetics and optogenetics can be
implemented in either mode, but the use of chemical photoswitches
is currently limited to downstream implementations. Even so, given
the high density of human foveal ganglion cells, the ultimate chemical
photoswitch treatment could deliver cost-effective, high-resolution
vision for the blind.
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Affiliation(s)
- Robert Marc
- Department of Ophthalmology, University of Utah School of Medicine, Salt Lake City, Utah 84132, United States
| | - Rebecca Pfeiffer
- Department of Ophthalmology, University of Utah School of Medicine, Salt Lake City, Utah 84132, United States
| | - Bryan Jones
- Department of Ophthalmology, University of Utah School of Medicine, Salt Lake City, Utah 84132, United States
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Haq W, Arango-Gonzalez B, Zrenner E, Euler T, Schubert T. Synaptic remodeling generates synchronous oscillations in the degenerated outer mouse retina. Front Neural Circuits 2014; 8:108. [PMID: 25249942 PMCID: PMC4155782 DOI: 10.3389/fncir.2014.00108] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Accepted: 08/19/2014] [Indexed: 11/28/2022] Open
Abstract
During neuronal degenerative diseases, neuronal microcircuits undergo severe structural alterations, leading to remodeling of synaptic connectivity. The functional consequences of such remodeling are mostly unknown. For instance, in mutant rd1 mouse retina, a common model for Retinitis Pigmentosa, rod bipolar cells (RBCs) establish contacts with remnant cone photoreceptors (cones) as a consequence of rod photoreceptor cell death and the resulting lack of presynaptic input. To assess the functional connectivity in the remodeled, light-insensitive outer rd1 retina, we recorded spontaneous population activity in retinal wholemounts using Ca(2+) imaging and identified the participating cell types. Focusing on cones, RBCs and horizontal cells (HCs), we found that these cell types display spontaneous oscillatory activity and form synchronously active clusters. Overall activity was modulated by GABAergic inhibition from interneurons such as HCs and/or possibly interplexiform cells. Many of the activity clusters comprised both cones and RBCs. Opposite to what is expected from the intact (wild-type) cone-ON bipolar cell pathway, cone and RBC activity was positively correlated and, at least partially, mediated by glutamate transporters expressed on RBCs. Deletion of gap junctional coupling between cones reduced the number of clusters, indicating that electrical cone coupling plays a crucial role for generating the observed synchronized oscillations. In conclusion, degeneration-induced synaptic remodeling of the rd1 retina results in a complex self-sustained outer retinal oscillatory network, that complements (and potentially modulates) the recently described inner retinal oscillatory network consisting of amacrine, bipolar and ganglion cells.
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Affiliation(s)
- Wadood Haq
- Centre for Ophthalmology, Institute for Ophthalmic Research, University of TübingenTübingen, Germany
- Werner Reichardt Centre for Integrative Neuroscience (CIN), University of TübingenTübingen, Germany
- Bernstein Center for Computational Neuroscience Tübingen, University of TübingenTübingen, Germany
| | - Blanca Arango-Gonzalez
- Centre for Ophthalmology, Institute for Ophthalmic Research, University of TübingenTübingen, Germany
| | - Eberhart Zrenner
- Centre for Ophthalmology, Institute for Ophthalmic Research, University of TübingenTübingen, Germany
- Werner Reichardt Centre for Integrative Neuroscience (CIN), University of TübingenTübingen, Germany
- Bernstein Center for Computational Neuroscience Tübingen, University of TübingenTübingen, Germany
| | - Thomas Euler
- Centre for Ophthalmology, Institute for Ophthalmic Research, University of TübingenTübingen, Germany
- Werner Reichardt Centre for Integrative Neuroscience (CIN), University of TübingenTübingen, Germany
- Bernstein Center for Computational Neuroscience Tübingen, University of TübingenTübingen, Germany
| | - Timm Schubert
- Centre for Ophthalmology, Institute for Ophthalmic Research, University of TübingenTübingen, Germany
- Werner Reichardt Centre for Integrative Neuroscience (CIN), University of TübingenTübingen, Germany
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234
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BARRETT JOHNMARTIN, BERLINGUER-PALMINI ROLANDO, DEGENAAR PATRICK. Optogenetic approaches to retinal prosthesis. Vis Neurosci 2014; 31:345-54. [PMID: 25100257 PMCID: PMC4161214 DOI: 10.1017/s0952523814000212] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Accepted: 05/07/2014] [Indexed: 01/14/2023]
Abstract
The concept of visual restoration via retinal prosthesis arguably started in 1992 with the discovery that some of the retinal cells were still intact in those with the retinitis pigmentosa disease. Two decades later, the first commercially available devices have the capability to allow users to identify basic shapes. Such devices are still very far from returning vision beyond the legal blindness. Thus, there is considerable continued development of electrode materials, and structures and electronic control mechanisms to increase both resolution and contrast. In parallel, the field of optogenetics--the genetic photosensitization of neural tissue holds particular promise for new approaches. Given that the eye is transparent, photosensitizing remaining neural layers of the eye and illuminating from the outside could prove to be less invasive, cheaper, and more effective than present approaches. As we move toward human trials in the coming years, this review explores the core technological and biological challenges related to the gene therapy and the high radiance optical stimulation requirement.
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Affiliation(s)
- JOHN MARTIN BARRETT
- Institute of Neuroscience,
Newcastle University, Newcastle upon
Tyne, United Kingdom
| | | | - PATRICK DEGENAAR
- School of EEE,
Newcastle University, Newcastle upon
Tyne, United Kingdom
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235
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Menzler J, Channappa L, Zeck G. Rhythmic ganglion cell activity in bleached and blind adult mouse retinas. PLoS One 2014; 9:e106047. [PMID: 25153888 PMCID: PMC4143350 DOI: 10.1371/journal.pone.0106047] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Accepted: 07/31/2014] [Indexed: 12/02/2022] Open
Abstract
In retinitis pigmentosa – a degenerative disease which often leads to incurable blindness- the loss of photoreceptors deprives the retina from a continuous excitatory input, the so-called dark current. In rodent models of this disease this deprivation leads to oscillatory electrical activity in the remaining circuitry, which is reflected in the rhythmic spiking of retinal ganglion cells (RGCs). It remained unclear, however, if the rhythmic RGC activity is attributed to circuit alterations occurring during photoreceptor degeneration or if rhythmic activity is an intrinsic property of healthy retinal circuitry which is masked by the photoreceptor’s dark current. Here we tested these hypotheses by inducing and analysing oscillatory activity in adult healthy (C57/Bl6) and blind mouse retinas (rd10 and rd1). Rhythmic RGC activity in healthy retinas was detected upon partial photoreceptor bleaching using an extracellular high-density multi-transistor-array. The mean fundamental spiking frequency in bleached retinas was 4.3 Hz; close to the RGC rhythm detected in blind rd10 mouse retinas (6.5 Hz). Crosscorrelation analysis of neighbouring wild-type and rd10 RGCs (separation distance <200 µm) reveals synchrony among homologous RGC types and a constant phase shift (∼70 msec) among heterologous cell types (ON versus OFF). The rhythmic RGC spiking in these retinas is driven by a network of presynaptic neurons. The inhibition of glutamatergic ganglion cell input or the inhibition of gap junctional coupling abolished the rhythmic pattern. In rd10 and rd1 retinas the presynaptic network leads to local field potentials, whereas in bleached retinas additional pharmacological disinhibition is required to achieve detectable field potentials. Our results demonstrate that photoreceptor bleaching unmasks oscillatory activity in healthy retinas which shares many features with the functional phenotype detected in rd10 retinas. The quantitative physiological differences advance the understanding of the degeneration process and may guide future rescue strategies.
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Affiliation(s)
- Jacob Menzler
- Neurochip Research Group, Natural and Medical Sciences Institute at the University Tübingen, Reutlingen, Germany
- Helmholtz Zentrum München, Deutsches Forschungszentrum für Gesundheit und Umwelt, Neuherberg, Germany
| | - Lakshmi Channappa
- Neurochip Research Group, Natural and Medical Sciences Institute at the University Tübingen, Reutlingen, Germany
| | - Guenther Zeck
- Neurochip Research Group, Natural and Medical Sciences Institute at the University Tübingen, Reutlingen, Germany
- * E-mail:
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236
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Macé E, Caplette R, Marre O, Sengupta A, Chaffiol A, Barbe P, Desrosiers M, Bamberg E, Sahel JA, Picaud S, Duebel J, Dalkara D. Targeting channelrhodopsin-2 to ON-bipolar cells with vitreally administered AAV Restores ON and OFF visual responses in blind mice. Mol Ther 2014; 23:7-16. [PMID: 25095892 DOI: 10.1038/mt.2014.154] [Citation(s) in RCA: 130] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Accepted: 07/29/2014] [Indexed: 12/12/2022] Open
Abstract
Most inherited retinal dystrophies display progressive photoreceptor cell degeneration leading to severe visual impairment. Optogenetic reactivation of retinal neurons mediated by adeno-associated virus (AAV) gene therapy has the potential to restore vision regardless of patient-specific mutations. The challenge for clinical translatability is to restore a vision as close to natural vision as possible, while using a surgically safe delivery route for the fragile degenerated retina. To preserve the visual processing of the inner retina, we targeted ON bipolar cells, which are still present at late stages of disease. For safe gene delivery, we used a recently engineered AAV variant that can transduce the bipolar cells after injection into the eye's easily accessible vitreous humor. We show that AAV encoding channelrhodopsin under the ON bipolar cell-specific promoter mediates long-term gene delivery restricted to ON-bipolar cells after intravitreal administration. Channelrhodopsin expression in ON bipolar cells leads to restoration of ON and OFF responses at the retinal and cortical levels. Moreover, light-induced locomotory behavior is restored in treated blind mice. Our results support the clinical relevance of a minimally invasive AAV-mediated optogenetic therapy for visual restoration.
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Affiliation(s)
- Emilie Macé
- 1] INSERM, U968, Paris, France [2] Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris, France [3] CNRS, UMR_7210, Paris, France
| | - Romain Caplette
- 1] INSERM, U968, Paris, France [2] Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris, France [3] CNRS, UMR_7210, Paris, France
| | - Olivier Marre
- 1] INSERM, U968, Paris, France [2] Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris, France [3] CNRS, UMR_7210, Paris, France
| | - Abhishek Sengupta
- 1] INSERM, U968, Paris, France [2] Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris, France [3] CNRS, UMR_7210, Paris, France
| | - Antoine Chaffiol
- 1] INSERM, U968, Paris, France [2] Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris, France [3] CNRS, UMR_7210, Paris, France
| | - Peggy Barbe
- 1] INSERM, U968, Paris, France [2] Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris, France [3] CNRS, UMR_7210, Paris, France
| | - Mélissa Desrosiers
- 1] INSERM, U968, Paris, France [2] Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris, France [3] CNRS, UMR_7210, Paris, France
| | - Ernst Bamberg
- Department of Biophysical Chemistry, Max Planck Institute of Biophysics, Frankfurt am Main, Germany
| | - Jose-Alain Sahel
- 1] INSERM, U968, Paris, France [2] Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris, France [3] CNRS, UMR_7210, Paris, France [4] Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, INSERM-DHOS CIC 503, Paris, France [5] Fondation Ophtalmologique Adolphe de Rothschild, Paris, France
| | - Serge Picaud
- 1] INSERM, U968, Paris, France [2] Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris, France [3] CNRS, UMR_7210, Paris, France
| | - Jens Duebel
- 1] INSERM, U968, Paris, France [2] Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris, France [3] CNRS, UMR_7210, Paris, France
| | - Deniz Dalkara
- 1] INSERM, U968, Paris, France [2] Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris, France [3] CNRS, UMR_7210, Paris, France
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237
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Cuenca N, Fernández-Sánchez L, Campello L, Maneu V, De la Villa P, Lax P, Pinilla I. Cellular responses following retinal injuries and therapeutic approaches for neurodegenerative diseases. Prog Retin Eye Res 2014; 43:17-75. [PMID: 25038518 DOI: 10.1016/j.preteyeres.2014.07.001] [Citation(s) in RCA: 302] [Impact Index Per Article: 30.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 07/03/2014] [Accepted: 07/07/2014] [Indexed: 01/17/2023]
Abstract
Retinal neurodegenerative diseases like age-related macular degeneration, glaucoma, diabetic retinopathy and retinitis pigmentosa each have a different etiology and pathogenesis. However, at the cellular and molecular level, the response to retinal injury is similar in all of them, and results in morphological and functional impairment of retinal cells. This retinal degeneration may be triggered by gene defects, increased intraocular pressure, high levels of blood glucose, other types of stress or aging, but they all frequently induce a set of cell signals that lead to well-established and similar morphological and functional changes, including controlled cell death and retinal remodeling. Interestingly, an inflammatory response, oxidative stress and activation of apoptotic pathways are common features in all these diseases. Furthermore, it is important to note the relevant role of glial cells, including astrocytes, Müller cells and microglia, because their response to injury is decisive for maintaining the health of the retina or its degeneration. Several therapeutic approaches have been developed to preserve retinal function or restore eyesight in pathological conditions. In this context, neuroprotective compounds, gene therapy, cell transplantation or artificial devices should be applied at the appropriate stage of retinal degeneration to obtain successful results. This review provides an overview of the common and distinctive features of retinal neurodegenerative diseases, including the molecular, anatomical and functional changes caused by the cellular response to damage, in order to establish appropriate treatments for these pathologies.
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Affiliation(s)
- Nicolás Cuenca
- Department of Physiology, Genetics and Microbiology, University of Alicante, Alicante, Spain; Multidisciplinary Institute for Environmental Studies "Ramon Margalef", University of Alicante, Alicante, Spain.
| | - Laura Fernández-Sánchez
- Department of Physiology, Genetics and Microbiology, University of Alicante, Alicante, Spain
| | - Laura Campello
- Department of Physiology, Genetics and Microbiology, University of Alicante, Alicante, Spain
| | - Victoria Maneu
- Department of Optics, Pharmacology and Anatomy, University of Alicante, Alicante, Spain
| | - Pedro De la Villa
- Department of Systems Biology, University of Alcalá, Alcalá de Henares, Spain
| | - Pedro Lax
- Department of Physiology, Genetics and Microbiology, University of Alicante, Alicante, Spain
| | - Isabel Pinilla
- Department of Ophthalmology, Lozano Blesa University Hospital, Aragon Institute of Health Sciences, Zaragoza, Spain
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238
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Choi H, Zhang L, Cembrowski MS, Sabottke CF, Markowitz AL, Butts DA, Kath WL, Singer JH, Riecke H. Intrinsic bursting of AII amacrine cells underlies oscillations in the rd1 mouse retina. J Neurophysiol 2014; 112:1491-504. [PMID: 25008417 DOI: 10.1152/jn.00437.2014] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
In many forms of retinal degeneration, photoreceptors die but inner retinal circuits remain intact. In the rd1 mouse, an established model for blinding retinal diseases, spontaneous activity in the coupled network of AII amacrine and ON cone bipolar cells leads to rhythmic bursting of ganglion cells. Since such activity could impair retinal and/or cortical responses to restored photoreceptor function, understanding its nature is important for developing treatments of retinal pathologies. Here we analyzed a compartmental model of the wild-type mouse AII amacrine cell to predict that the cell's intrinsic membrane properties, specifically, interacting fast Na and slow, M-type K conductances, would allow its membrane potential to oscillate when light-evoked excitatory synaptic inputs were withdrawn following photoreceptor degeneration. We tested and confirmed this hypothesis experimentally by recording from AIIs in a slice preparation of rd1 retina. Additionally, recordings from ganglion cells in a whole mount preparation of rd1 retina demonstrated that activity in AIIs was propagated unchanged to elicit bursts of action potentials in ganglion cells. We conclude that oscillations are not an emergent property of a degenerated retinal network. Rather, they arise largely from the intrinsic properties of a single retinal interneuron, the AII amacrine cell.
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Affiliation(s)
- Hannah Choi
- Department of Engineering Sciences and Applied Mathematics, Northwestern University, Evanston, Illinois
| | - Lei Zhang
- Department of Biology, University of Maryland, College Park, Maryland; and
| | - Mark S Cembrowski
- Howard Hughes Medical Institute, Janelia Farm Research Campus, Ashburn, Virginia
| | - Carl F Sabottke
- Department of Biology, University of Maryland, College Park, Maryland; and
| | | | - Daniel A Butts
- Department of Biology, University of Maryland, College Park, Maryland; and
| | - William L Kath
- Department of Engineering Sciences and Applied Mathematics, Northwestern University, Evanston, Illinois
| | - Joshua H Singer
- Department of Biology, University of Maryland, College Park, Maryland; and
| | - Hermann Riecke
- Department of Engineering Sciences and Applied Mathematics, Northwestern University, Evanston, Illinois;
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239
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Hoon M, Okawa H, Della Santina L, Wong ROL. Functional architecture of the retina: development and disease. Prog Retin Eye Res 2014; 42:44-84. [PMID: 24984227 DOI: 10.1016/j.preteyeres.2014.06.003] [Citation(s) in RCA: 348] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Revised: 06/08/2014] [Accepted: 06/22/2014] [Indexed: 12/22/2022]
Abstract
Structure and function are highly correlated in the vertebrate retina, a sensory tissue that is organized into cell layers with microcircuits working in parallel and together to encode visual information. All vertebrate retinas share a fundamental plan, comprising five major neuronal cell classes with cell body distributions and connectivity arranged in stereotypic patterns. Conserved features in retinal design have enabled detailed analysis and comparisons of structure, connectivity and function across species. Each species, however, can adopt structural and/or functional retinal specializations, implementing variations to the basic design in order to satisfy unique requirements in visual function. Recent advances in molecular tools, imaging and electrophysiological approaches have greatly facilitated identification of the cellular and molecular mechanisms that establish the fundamental organization of the retina and the specializations of its microcircuits during development. Here, we review advances in our understanding of how these mechanisms act to shape structure and function at the single cell level, to coordinate the assembly of cell populations, and to define their specific circuitry. We also highlight how structure is rearranged and function is disrupted in disease, and discuss current approaches to re-establish the intricate functional architecture of the retina.
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Affiliation(s)
- Mrinalini Hoon
- Department of Biological Structure, University of Washington, 1959 NE Pacific Street, Seattle, WA 98195, USA
| | - Haruhisa Okawa
- Department of Biological Structure, University of Washington, 1959 NE Pacific Street, Seattle, WA 98195, USA
| | - Luca Della Santina
- Department of Biological Structure, University of Washington, 1959 NE Pacific Street, Seattle, WA 98195, USA
| | - Rachel O L Wong
- Department of Biological Structure, University of Washington, 1959 NE Pacific Street, Seattle, WA 98195, USA.
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240
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ChR2 mutants at L132 and T159 with improved operational light sensitivity for vision restoration. PLoS One 2014; 9:e98924. [PMID: 24901492 PMCID: PMC4047080 DOI: 10.1371/journal.pone.0098924] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2014] [Accepted: 05/08/2014] [Indexed: 11/19/2022] Open
Abstract
The ectopic expression of microbial opsin-based optogenetic sensors, such as channelrhodopsin-2 (ChR2) in surviving inner retinal neurons, is a promising approach to restoring vision after retinal degeneration. However, a major limitation in using native ChR2 as a light sensor for vision restoration is the low light sensitivity of its expressing cells. Recently, two ChR2 mutations, T159C and L132C, were reported to produce higher photocurrents or have ultra light sensitivity. In this study, we created additional ChR2 mutants at these two sites to search for more light responsive ChR2 forms and evaluate their suitability for vision restoration by examining their light responsive properties in HEK cells and mouse retinal ganglion cells. We found additional ChR2 mutants at these two sites that showed a further increase in current amplitude at low light levels in the cells expressing these mutants, or operational light sensitivity. However, the increase in the operational light sensitivity was correlated with a decrease in temporal kinetics. Therefore, there is a trade-off between operational light sensitivity and temporal resolution for these more light responsive ChR2 mutants. Our results showed that for the two most light responsive mutants, L132C/T159C and L132C/T159S, the required light intensities for generating the threshold spiking activity in retinal ganglion cells were 1.5 and nearly 2 log units lower than wild-type ChR2 (wt-ChR2), respectively. Additionally, their ChR2-mediated spiking activities could follow flicker frequencies up to 20 and 10 Hz, respectively, at light intensities up to 1.5 log units above their threshold levels. Thus, the use of these more light responsive ChR2 mutants could make the optogenetic approach to restoring vision more feasible.
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241
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Tomita H, Sugano E, Murayama N, Ozaki T, Nishiyama F, Tabata K, Takahashi M, Saito T, Tamai M. Restoration of the majority of the visual spectrum by using modified Volvox channelrhodopsin-1. Mol Ther 2014; 22:1434-1440. [PMID: 24821344 PMCID: PMC4435592 DOI: 10.1038/mt.2014.81] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Accepted: 04/29/2014] [Indexed: 11/12/2022] Open
Abstract
We previously showed that blind rats whose vision was restored by gene transfer of Chlamydomonas channelrhodopsin-2 (ChR2) could only detect wavelengths less than 540 nm because of the action spectrum of the transgene product. Volvox-derived channelrhodopsin-1, VChR1, has a broader spectrum than ChR2. However, the VChR1 protein was mainly localized in the cytoplasm and showed weak ion channel properties when the VChR1 gene was transfected into HEK293 cells. We generated modified Volvox channelrhodopsin-1 (mVChR1), which is a chimera of Volvox channelrhodopsin-1 and Chlamydomonas channelrhodopsin-1 and demonstrated increased plasma membrane integration and dramatic improvement in its channel properties. Under whole-cell patch clamp, mVChR1-expressing cells showed a photo-induced current upon stimulation at 468–640 nm. The evoked currents in mVChR1-expressing cells were ~30 times larger than those in VChR1-expressing cells. Genetically, blind rats expressing mVChR1 via an adeno-associated virus vector regained their visual responses to light with wavelengths between 468 and 640 nm and their recovered visual responses were maintained for a year. Thus, mVChR1 is a candidate gene for gene therapy for restoring vision, and gene delivery of mVChR1 may provide blind patients access to the majority of the visible light spectrum.
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Affiliation(s)
- Hiroshi Tomita
- Laboratory of Visual Neuroscience, Department of Chemistry and Bioengineering, Iwate University Graduate School of Engineering, Morioka, Iwate, Japan; Clinical Research, Innovation and Education Center, Tohoku University Hospital, Sendai, Miyagi, Japan.
| | - Eriko Sugano
- Laboratory of Visual Neuroscience, Department of Chemistry and Bioengineering, Iwate University Graduate School of Engineering, Morioka, Iwate, Japan
| | - Namie Murayama
- Laboratory of Visual Neuroscience, Department of Chemistry and Bioengineering, Iwate University Graduate School of Engineering, Morioka, Iwate, Japan
| | - Taku Ozaki
- Department of Ophthalmology, Hirosaki University Graduate School of Medicine, Hirosaki, Aomori, Japan
| | - Fumiaki Nishiyama
- Laboratory of Visual Neuroscience, Department of Chemistry and Bioengineering, Iwate University Graduate School of Engineering, Morioka, Iwate, Japan
| | - Kitako Tabata
- Laboratory of Visual Neuroscience, Department of Chemistry and Bioengineering, Iwate University Graduate School of Engineering, Morioka, Iwate, Japan
| | - Maki Takahashi
- Laboratory of Visual Neuroscience, Department of Chemistry and Bioengineering, Iwate University Graduate School of Engineering, Morioka, Iwate, Japan
| | - Takehiko Saito
- Laboratory of Visual Neuroscience, Department of Chemistry and Bioengineering, Iwate University Graduate School of Engineering, Morioka, Iwate, Japan
| | - Makoto Tamai
- Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan
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242
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Bareket-Keren L, Hanein Y. Novel interfaces for light directed neuronal stimulation: advances and challenges. Int J Nanomedicine 2014; 9 Suppl 1:65-83. [PMID: 24872704 PMCID: PMC4024977 DOI: 10.2147/ijn.s51193] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Light activation of neurons is a growing field with applications ranging from basic investigation of neuronal systems to the development of new therapeutic methods such as artificial retina. Many recent studies currently explore novel methods for optical stimulation with temporal and spatial precision. Novel materials in particular provide an opportunity to enhance contemporary approaches. Here we review recent advances towards light directed interfaces for neuronal stimulation, focusing on state-of-the-art nanoengineered devices. In particular, we highlight challenges and prospects towards improved retinal prostheses.
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Affiliation(s)
- Lilach Bareket-Keren
- School of Electrical Engineering, Tel-Aviv University, Tel-Aviv University, Tel-Aviv, Israel ; Tel-Aviv University Center for Nanoscience and Nanotechnology, Tel-Aviv University, Tel-Aviv, Israel
| | - Yael Hanein
- School of Electrical Engineering, Tel-Aviv University, Tel-Aviv University, Tel-Aviv, Israel ; Tel-Aviv University Center for Nanoscience and Nanotechnology, Tel-Aviv University, Tel-Aviv, Israel
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243
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Rowe-Rendleman CL, Durazo SA, Kompella UB, Rittenhouse KD, Di Polo A, Weiner AL, Grossniklaus HE, Naash MI, Lewin AS, Horsager A, Edelhauser HF. Drug and gene delivery to the back of the eye: from bench to bedside. Invest Ophthalmol Vis Sci 2014; 55:2714-30. [PMID: 24777644 DOI: 10.1167/iovs.13-13707] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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244
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Dalkara D, Sahel JA. Gene therapy for inherited retinal degenerations. C R Biol 2014; 337:185-92. [DOI: 10.1016/j.crvi.2014.01.002] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Accepted: 01/06/2014] [Indexed: 11/28/2022]
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245
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Tochitsky I, Polosukhina A, Degtyar VE, Gallerani N, Smith CM, Friedman A, Van Gelder RN, Trauner D, Kaufer D, Kramer RH. Restoring visual function to blind mice with a photoswitch that exploits electrophysiological remodeling of retinal ganglion cells. Neuron 2014; 81:800-13. [PMID: 24559673 PMCID: PMC3933823 DOI: 10.1016/j.neuron.2014.01.003] [Citation(s) in RCA: 112] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/19/2013] [Indexed: 10/25/2022]
Abstract
Retinitis pigmentosa (RP) and age-related macular degeneration (AMD) are blinding diseases caused by the degeneration of rods and cones, leaving the remainder of the visual system unable to respond to light. Here, we report a chemical photoswitch named DENAQ that restores retinal responses to white light of intensity similar to ordinary daylight. A single intraocular injection of DENAQ photosensitizes the blind retina for days, restoring electrophysiological and behavioral responses with no toxicity. Experiments on mouse strains with functional, nonfunctional, or degenerated rods and cones show that DENAQ is effective only in retinas with degenerated photoreceptors. DENAQ confers light sensitivity on a hyperpolarization-activated inward current that is enhanced in degenerated retina, enabling optical control of retinal ganglion cell firing. The acceptable light sensitivity, favorable spectral sensitivity, and selective targeting to diseased tissue make DENAQ a prime drug candidate for vision restoration in patients with end-stage RP and AMD.
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Affiliation(s)
- Ivan Tochitsky
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Aleksandra Polosukhina
- Vision Science Graduate Group, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Vadim E Degtyar
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Nicholas Gallerani
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Caleb M Smith
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Aaron Friedman
- Department of Integrative Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Russell N Van Gelder
- Departments of Ophthalmology, Pathology, and Biological Structure, University of Washington, Seattle, WA 98195, USA
| | - Dirk Trauner
- Department of Chemistry and Biochemistry, University of Munich, 81377 Munich, Germany
| | - Daniela Kaufer
- Department of Integrative Biology, University of California, Berkeley, Berkeley, CA 94720, USA; Helen Wills Neurosciences Institute, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Richard H Kramer
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA; Vision Science Graduate Group, University of California, Berkeley, Berkeley, CA 94720, USA; Helen Wills Neurosciences Institute, University of California, Berkeley, Berkeley, CA 94720, USA.
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246
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Hernandez VH, Gehrt A, Reuter K, Jing Z, Jeschke M, Mendoza Schulz A, Hoch G, Bartels M, Vogt G, Garnham CW, Yawo H, Fukazawa Y, Augustine GJ, Bamberg E, Kügler S, Salditt T, de Hoz L, Strenzke N, Moser T. Optogenetic stimulation of the auditory pathway. J Clin Invest 2014; 124:1114-29. [PMID: 24509078 DOI: 10.1172/jci69050] [Citation(s) in RCA: 106] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Accepted: 11/21/2013] [Indexed: 12/18/2022] Open
Abstract
Auditory prostheses can partially restore speech comprehension when hearing fails. Sound coding with current prostheses is based on electrical stimulation of auditory neurons and has limited frequency resolution due to broad current spread within the cochlea. In contrast, optical stimulation can be spatially confined, which may improve frequency resolution. Here, we used animal models to characterize optogenetic stimulation, which is the optical stimulation of neurons genetically engineered to express the light-gated ion channel channelrhodopsin-2 (ChR2). Optogenetic stimulation of spiral ganglion neurons (SGNs) activated the auditory pathway, as demonstrated by recordings of single neuron and neuronal population responses. Furthermore, optogenetic stimulation of SGNs restored auditory activity in deaf mice. Approximation of the spatial spread of cochlear excitation by recording local field potentials (LFPs) in the inferior colliculus in response to suprathreshold optical, acoustic, and electrical stimuli indicated that optogenetic stimulation achieves better frequency resolution than monopolar electrical stimulation. Virus-mediated expression of a ChR2 variant with greater light sensitivity in SGNs reduced the amount of light required for responses and allowed neuronal spiking following stimulation up to 60 Hz. Our study demonstrates a strategy for optogenetic stimulation of the auditory pathway in rodents and lays the groundwork for future applications of cochlear optogenetics in auditory research and prosthetics.
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247
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Margolis DJ, Gartland AJ, Singer JH, Detwiler PB. Network oscillations drive correlated spiking of ON and OFF ganglion cells in the rd1 mouse model of retinal degeneration. PLoS One 2014; 9:e86253. [PMID: 24489706 PMCID: PMC3904909 DOI: 10.1371/journal.pone.0086253] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Accepted: 12/12/2013] [Indexed: 11/19/2022] Open
Abstract
Following photoreceptor degeneration, ON and OFF retinal ganglion cells (RGCs) in the rd-1/rd-1 mouse receive rhythmic synaptic input that elicits bursts of action potentials at ∼ 10 Hz. To characterize the properties of this activity, RGCs were targeted for paired recording and morphological classification as either ON alpha, OFF alpha or non-alpha RGCs using two-photon imaging. Identified cell types exhibited rhythmic spike activity. Cross-correlation of spike trains recorded simultaneously from pairs of RGCs revealed that activity was correlated more strongly between alpha RGCs than between alpha and non-alpha cell pairs. Bursts of action potentials in alpha RGC pairs of the same type, i.e. two ON or two OFF cells, were in phase, while bursts in dissimilar alpha cell types, i.e. an ON and an OFF RGC, were 180 degrees out of phase. This result is consistent with RGC activity being driven by an input that provides correlated excitation to ON cells and inhibition to OFF cells. A2 amacrine cells were investigated as a candidate cellular mechanism and found to display 10 Hz oscillations in membrane voltage and current that persisted in the presence of antagonists of fast synaptic transmission and were eliminated by tetrodotoxin. Results support the conclusion that the rhythmic RGC activity originates in a presynaptic network of electrically coupled cells including A2s via a Na(+)-channel dependent mechanism. Network activity drives out of phase oscillations in ON and OFF cone bipolar cells, entraining similar frequency fluctuations in RGC spike activity over an area of retina that migrates with changes in the spatial locus of the cellular oscillator.
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Affiliation(s)
- David J. Margolis
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, United States of America
- * E-mail: (DJM); (PBD)
| | - Andrew J. Gartland
- Department Physiology and Biophysics and Program in Neurobiology and Behavior, University of Washington, Seattle, Washington, United States of America
| | - Joshua H. Singer
- Department of Biology, University of Maryland, College Park, Maryland, United States of America
| | - Peter B. Detwiler
- Department Physiology and Biophysics and Program in Neurobiology and Behavior, University of Washington, Seattle, Washington, United States of America
- * E-mail: (DJM); (PBD)
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Dalkara D, Byrne LC, Klimczak RR, Visel M, Yin L, Merigan WH, Flannery JG, Schaffer DV. In vivo-directed evolution of a new adeno-associated virus for therapeutic outer retinal gene delivery from the vitreous. Sci Transl Med 2014; 5:189ra76. [PMID: 23761039 DOI: 10.1126/scitranslmed.3005708] [Citation(s) in RCA: 490] [Impact Index Per Article: 49.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Inherited retinal degenerative diseases are a clinically promising focus of adeno-associated virus (AAV)-mediated gene therapy. These diseases arise from pathogenic mutations in mRNA transcripts expressed in the eye's photoreceptor cells or retinal pigment epithelium (RPE), leading to cell death and structural deterioration. Because current gene delivery methods require an injurious subretinal injection to reach the photoreceptors or RPE and transduce just a fraction of the retina, they are suitable only for the treatment of rare degenerative diseases in which retinal structures remain intact. To address the need for broadly applicable gene delivery approaches, we implemented in vivo-directed evolution to engineer AAV variants that deliver the gene cargo to the outer retina after injection into the eye's easily accessible vitreous humor. This approach has general implications for situations in which dense tissue penetration poses a barrier for gene delivery. A resulting AAV variant mediated widespread delivery to the outer retina and rescued the disease phenotypes of X-linked retinoschisis and Leber's congenital amaurosis in corresponding mouse models. Furthermore, it enabled transduction of primate photoreceptors from the vitreous, expanding its therapeutic promise.
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Affiliation(s)
- Deniz Dalkara
- Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720-1462, USA
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249
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Focal damage to macaque photoreceptors produces persistent visual loss. Exp Eye Res 2013; 119:88-96. [PMID: 24316158 DOI: 10.1016/j.exer.2013.11.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2013] [Revised: 10/02/2013] [Accepted: 11/01/2013] [Indexed: 11/23/2022]
Abstract
Insertion of light-gated channels into inner retina neurons restores neural light responses, light evoked potentials, visual optomotor responses and visually-guided maze behavior in mice blinded by retinal degeneration. This method of vision restoration bypasses damaged outer retina, providing stimulation directly to retinal ganglion cells in inner retina. The approach is similar to that of electronic visual protheses, but may offer some advantages, such as avoidance of complex surgery and direct targeting of many thousands of neurons. However, the promise of this technique for restoring human vision remains uncertain because rodent animal models, in which it has been largely developed, are not ideal for evaluating visual perception. On the other hand, psychophysical vision studies in macaque can be used to evaluate different approaches to vision restoration in humans. Furthermore, it has not been possible to test vision restoration in macaques, the optimal model for human-like vision, because there has been no macaque model of outer retina degeneration. In this study, we describe development of a macaque model of photoreceptor degeneration that can in future studies be used to test restoration of perception by visual prostheses. Our results show that perceptual deficits caused by focal light damage are restricted to locations at which photoreceptors are damaged, that optical coherence tomography (OCT) can be used to track such lesions, and that adaptive optics retinal imaging, which we recently used for in vivo recording of ganglion cell function, can be used in future studies to examine these lesions.
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250
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Functional rescue of cone photoreceptors in retinitis pigmentosa. Graefes Arch Clin Exp Ophthalmol 2013; 251:1669-77. [PMID: 23575948 DOI: 10.1007/s00417-013-2314-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
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