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Reyes-Ortega P, Rodríguez-Arzate A, Noguez-Imm R, Arnold E, Thébault SC. Contribution of chemical and electrical transmission to the low delta-like intrinsic retinal oscillation in mice: A role for daylight-activated neuromodulators. Eur J Pharmacol 2024; 968:176384. [PMID: 38342360 DOI: 10.1016/j.ejphar.2024.176384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 01/16/2024] [Accepted: 02/01/2024] [Indexed: 02/13/2024]
Abstract
Basal electroretinogram (ERG) oscillations have shown predictive value for modifiable risk factors for type 2 diabetes. However, their origin remains unknown. Here, we seek to establish the pharmacological profile of the low delta-like (δ1) wave in the mouse because it shows light sensitivity in the form of a decreased peak frequency upon photopic exposure. Applying neuropharmacological drugs by intravitreal injection, we eliminated the δ1 wave using lidocaine or by blocking all chemical and electrical synapses. The δ1 wave was insensitive to the blockade of photoreceptor input, but was accelerated when all inhibitory or ionotropic inhibitory receptors in the retina were antagonized. The sole blockade of GABAA, GABAB, GABAC, and glycine receptors also accelerated the δ1 wave. In contrast, the gap junction blockade slowed the δ1 wave. Both GABAA receptors and gap junctions contribute to the light sensitivity of the δ1 wave. We further found that the day light-activated neuromodulators dopamine and nitric oxide donors mimicked the effect of photopic exposure on the δ1 wave. All drug effects were validated through light flash-evoked ERG responses. Our data indicate that the low δ-like intrinsic wave detected by the non-photic ERG arises from an inner retinal circuit regulated by inhibitory neurotransmission and nitric oxide/dopamine-sensitive gap junction-mediated communication.
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Affiliation(s)
| | | | - Ramsés Noguez-Imm
- Laboratorio de Investigación Traslacional en Salud Visual D-13 y, Mexico
| | - Edith Arnold
- Laboratorio de Endocrinología Molecular A-14, Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Campus UNAM-Juriquilla, 76230, Querétaro, Mexico; CONAHCYT-Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Campus UNAM-Juriquilla, 76230 Querétaro, Mexico
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2
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Stoddart PR, Begeng JM, Tong W, Ibbotson MR, Kameneva T. Nanoparticle-based optical interfaces for retinal neuromodulation: a review. Front Cell Neurosci 2024; 18:1360870. [PMID: 38572073 PMCID: PMC10987880 DOI: 10.3389/fncel.2024.1360870] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2023] [Accepted: 03/04/2024] [Indexed: 04/05/2024] Open
Abstract
Degeneration of photoreceptors in the retina is a leading cause of blindness, but commonly leaves the retinal ganglion cells (RGCs) and/or bipolar cells extant. Consequently, these cells are an attractive target for the invasive electrical implants colloquially known as "bionic eyes." However, after more than two decades of concerted effort, interfaces based on conventional electrical stimulation approaches have delivered limited efficacy, primarily due to the current spread in retinal tissue, which precludes high-acuity vision. The ideal prosthetic solution would be less invasive, provide single-cell resolution and an ability to differentiate between different cell types. Nanoparticle-mediated approaches can address some of these requirements, with particular attention being directed at light-sensitive nanoparticles that can be accessed via the intrinsic optics of the eye. Here we survey the available known nanoparticle-based optical transduction mechanisms that can be exploited for neuromodulation. We review the rapid progress in the field, together with outstanding challenges that must be addressed to translate these techniques to clinical practice. In particular, successful translation will likely require efficient delivery of nanoparticles to stable and precisely defined locations in the retinal tissues. Therefore, we also emphasize the current literature relating to the pharmacokinetics of nanoparticles in the eye. While considerable challenges remain to be overcome, progress to date shows great potential for nanoparticle-based interfaces to revolutionize the field of visual prostheses.
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Affiliation(s)
- Paul R. Stoddart
- School of Science, Computing and Engineering Technologies, Swinburne University of Technology, Hawthorn, VIC, Australia
| | - James M. Begeng
- School of Science, Computing and Engineering Technologies, Swinburne University of Technology, Hawthorn, VIC, Australia
- Department of Biomedical Engineering, Faculty of Engineering & Information Technology, The University of Melbourne, Melbourne, VIC, Australia
| | - Wei Tong
- Department of Biomedical Engineering, Faculty of Engineering & Information Technology, The University of Melbourne, Melbourne, VIC, Australia
- School of Physics, The University of Melbourne, Melbourne, VIC, Australia
| | - Michael R. Ibbotson
- Department of Biomedical Engineering, Faculty of Engineering & Information Technology, The University of Melbourne, Melbourne, VIC, Australia
| | - Tatiana Kameneva
- School of Science, Computing and Engineering Technologies, Swinburne University of Technology, Hawthorn, VIC, Australia
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3
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Rodríguez-Arzate CA, Noguez-Imm R, Reyes-Ortega P, Rodríguez-Ortiz LR, García-Peña MF, Ordaz RP, Vélez-Uriza F, Cisneros-Mejorado A, Arellano RO, Pérez CI, Hernández-Zimbrón LF, Dégardin J, Simonutti M, Picaud S, Thébault SC. Potential contributions of the intrinsic retinal oscillations recording using non-invasive electroretinogram to bioelectronics. Front Cell Neurosci 2024; 17:1224558. [PMID: 38269118 PMCID: PMC10806452 DOI: 10.3389/fncel.2023.1224558] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 12/15/2023] [Indexed: 01/26/2024] Open
Abstract
Targeted electric signal use for disease diagnostics and treatment is emerging as a healthcare game-changer. Besides arrhythmias, treatment-resistant epilepsy and chronic pain, blindness, and perhaps soon vision loss, could be among the pathologies that benefit from bioelectronic medicine. The electroretinogram (ERG) technique has long demonstrated its role in diagnosing eye diseases and early stages of neurodegenerative diseases. Conspicuously, ERG applications are all based on light-induced responses. However, spontaneous, intrinsic activity also originates in retinal cells. It is a hallmark of degenerated retinas and its alterations accompany obesity and diabetes. To the extent that variables extracted from the resting activity of the retina measured by ERG allow the predictive diagnosis of risk factors for type 2 diabetes. Here, we provided a comparison of the baseline characteristics of intrinsic oscillatory activity recorded by ERGs in mice, rats, and humans, as well as in several rat strains, and explore whether zebrafish exhibit comparable activity. Their pattern was altered in neurodegenerative models including the cuprizone-induced demyelination model in mice as well as in the Royal College of Surgeons (RCS-/-) rats. We also discuss how the study of their properties may pave the way for future research directions and treatment approaches for retinopathies, among others.
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Affiliation(s)
- Cynthia Alejandra Rodríguez-Arzate
- Laboratorio de Investigación Traslacional en Salud Visual D-13, Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
| | - Ramsés Noguez-Imm
- Laboratorio de Investigación Traslacional en Salud Visual D-13, Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
| | - Pamela Reyes-Ortega
- Laboratorio de Investigación Traslacional en Salud Visual D-13, Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
| | - Luis Roberto Rodríguez-Ortiz
- Laboratorio de Neurobiología Molecular y Celular, Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
| | - María Fernanda García-Peña
- Laboratorio de Neurobiología Molecular y Celular, Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
| | - Rainald Pablo Ordaz
- Laboratorio de Neurofisiología Celular, Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
| | - Fidel Vélez-Uriza
- Laboratorio de Neurofisiología Celular, Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
| | - Abraham Cisneros-Mejorado
- Laboratorio de Neurofisiología Celular, Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
| | - Rogelio O. Arellano
- Laboratorio de Neurofisiología Celular, Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
| | - Claudia I. Pérez
- Laboratorio de Neurofisiología de los Hábitos, Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
| | - Luis Fernando Hernández-Zimbrón
- Clínica de Salud Visual, Escuela Nacional de Estudios Superiores, Unidad León, Universidad Nacional Autonóma de México (UNAM), León, Guanajuato, Mexico
| | - Julie Dégardin
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Manuel Simonutti
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Serge Picaud
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Stéphanie C. Thébault
- Laboratorio de Investigación Traslacional en Salud Visual D-13, Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
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Kramer RH. Suppressing Retinal Remodeling to Mitigate Vision Loss in Photoreceptor Degenerative Disorders. Annu Rev Vis Sci 2023; 9:131-153. [PMID: 37713276 DOI: 10.1146/annurev-vision-112122-020957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/17/2023]
Abstract
Rod and cone photoreceptors degenerate in retinitis pigmentosa and age-related macular degeneration, robbing the visual system of light-triggered signals necessary for sight. However, changes in the retina do not stop with the photoreceptors. A stereotypical set of morphological and physiological changes, known as remodeling, occur in downstream retinal neurons. Some aspects of remodeling are homeostatic, with structural or functional changes compensating for partial loss of visual inputs. However, other aspects are nonhomeostatic, corrupting retinal information processing to obscure vision mediated naturally by surviving photoreceptors or artificially by vision-restoration technologies. In this review, I consider the mechanism of remodeling and its consequences for residual and restored visual function; discuss the role of retinoic acid, a critical molecular trigger of detrimental remodeling; and discuss strategies for suppressing retinoic acid biosynthesis or signaling as therapeutic possibilities for mitigating vision loss.
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Affiliation(s)
- Richard H Kramer
- Department of Molecular and Cell Biology, University of California, Berkeley, USA;
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Xu A, Beyeler M. Retinal ganglion cells undergo cell type-specific functional changes in a computational model of cone-mediated retinal degeneration. Front Neurosci 2023; 17:1147729. [PMID: 37274203 PMCID: PMC10233015 DOI: 10.3389/fnins.2023.1147729] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Accepted: 05/02/2023] [Indexed: 06/06/2023] Open
Abstract
Introduction Understanding the retina in health and disease is a key issue for neuroscience and neuroengineering applications such as retinal prostheses. During degeneration, the retinal network undergoes complex and multi-stage neuroanatomical alterations, which drastically impact the retinal ganglion cell (RGC) response and are of clinical importance. Here we present a biophysically detailed in silico model of the cone pathway in the retina that simulates the network-level response to both light and electrical stimulation. Methods The model included 11, 138 cells belonging to nine different cell types (cone photoreceptors, horizontal cells, ON/OFF bipolar cells, ON/OFF amacrine cells, and ON/OFF ganglion cells) confined to a 300 × 300 × 210μm patch of the parafoveal retina. After verifying that the model reproduced seminal findings about the light response of retinal ganglion cells (RGCs), we systematically introduced anatomical and neurophysiological changes (e.g., reduced light sensitivity of photoreceptor, cell death, cell migration) to the network and studied their effect on network activity. Results The model was not only able to reproduce common findings about RGC activity in the degenerated retina, such as hyperactivity and increased electrical thresholds, but also offers testable predictions about the underlying neuroanatomical mechanisms. Discussion Overall, our findings demonstrate how biophysical changes typified by cone-mediated retinal degeneration may impact retinal responses to light and electrical stimulation. These insights may further our understanding of retinal processing and inform the design of retinal prostheses.
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Affiliation(s)
- Aiwen Xu
- Department of Computer Science, University of California, California, Santa Barbara, CA, United States
| | - Michael Beyeler
- Department of Computer Science, University of California, California, Santa Barbara, CA, United States
- Department of Psychological & Brain Sciences, University of California, California, Santa Barbara, CA, United States
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Noguez Imm R, Muñoz-Benitez J, Medina D, Barcenas E, Molero-Castillo G, Reyes-Ortega P, Hughes-Cano JA, Medrano-Gracia L, Miranda-Anaya M, Rojas-Piloni G, Quiroz-Mercado H, Hernández-Zimbrón LF, Fajardo-Cruz ED, Ferreyra-Severo E, García-Franco R, Rubio Mijangos JF, López-Star E, García-Roa M, Lansingh VC, Thébault SC. Preventable risk factors for type 2 diabetes can be detected using noninvasive spontaneous electroretinogram signals. PLoS One 2023; 18:e0278388. [PMID: 36634073 PMCID: PMC9836271 DOI: 10.1371/journal.pone.0278388] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Accepted: 11/15/2022] [Indexed: 01/13/2023] Open
Abstract
Given the ever-increasing prevalence of type 2 diabetes and obesity, the pressure on global healthcare is expected to be colossal, especially in terms of blindness. Electroretinogram (ERG) has long been perceived as a first-use technique for diagnosing eye diseases, and some studies suggested its use for preventable risk factors of type 2 diabetes and thereby diabetic retinopathy (DR). Here, we show that in a non-evoked mode, ERG signals contain spontaneous oscillations that predict disease cases in rodent models of obesity and in people with overweight, obesity, and metabolic syndrome but not yet diabetes, using one single random forest-based model. Classification performance was both internally and externally validated, and correlation analysis showed that the spontaneous oscillations of the non-evoked ERG are altered before oscillatory potentials, which are the current gold-standard for early DR. Principal component and discriminant analysis suggested that the slow frequency (0.4-0.7 Hz) components are the main discriminators for our predictive model. In addition, we established that the optimal conditions to record these informative signals, are 5-minute duration recordings under daylight conditions, using any ERG sensors, including ones working with portative, non-mydriatic devices. Our study provides an early warning system with promising applications for prevention, monitoring and even the development of new therapies against type 2 diabetes.
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Affiliation(s)
- Ramsés Noguez Imm
- Instituto de Neurobiología y Universidad Nacional Autónoma de México (UNAM), Campus UNAM-Juriquilla, Querétaro, Mexico
| | - Julio Muñoz-Benitez
- Facultad de Ingeniería, Universidad Nacional Autónoma de México (UNAM), Ciudad Universitaria, Ciudad de México, Mexico
| | - Diego Medina
- Facultad de Ingeniería, Universidad Nacional Autónoma de México (UNAM), Ciudad Universitaria, Ciudad de México, Mexico
| | - Everardo Barcenas
- Facultad de Ingeniería, Universidad Nacional Autónoma de México (UNAM), Ciudad Universitaria, Ciudad de México, Mexico
| | - Guillermo Molero-Castillo
- Facultad de Ingeniería, Universidad Nacional Autónoma de México (UNAM), Ciudad Universitaria, Ciudad de México, Mexico
| | - Pamela Reyes-Ortega
- Instituto de Neurobiología y Universidad Nacional Autónoma de México (UNAM), Campus UNAM-Juriquilla, Querétaro, Mexico
| | - Jorge Armando Hughes-Cano
- Instituto de Neurobiología y Universidad Nacional Autónoma de México (UNAM), Campus UNAM-Juriquilla, Querétaro, Mexico
| | | | - Manuel Miranda-Anaya
- Unidad Multidisciplinaria de Docencia e Investigación-Facultad de Ciencias, Universidad Nacional Autónoma de México (UNAM), Campus UNAM-Juriquilla, Querétaro, Mexico
| | - Gerardo Rojas-Piloni
- Instituto de Neurobiología y Universidad Nacional Autónoma de México (UNAM), Campus UNAM-Juriquilla, Querétaro, Mexico
| | | | - Luis Fernando Hernández-Zimbrón
- Research Department, Asociación Para Evitar la Ceguera, Mexico City, Mexico
- Clínica de Salud Visual, Escuela Nacional de Estudios Superiores, Unidad León, Universidad Nacional Autonóma de México (UNAM), León, Guanajuato, Mexico
| | | | | | - Renata García-Franco
- Instituto de la Retina del Bajío (INDEREB), Prolongación Constituyentes 302 (Consultorios 410 y 411, torre 3, Hospital San José), El jacal, Santiago de Querétaro, Querétaro, Mexico
| | - Juan Fernando Rubio Mijangos
- Instituto Mexicano de Oftalmología (IMO), I.A.P., Circuito Exterior Estadio Corregidora Sn, Centro Sur, Santiago de Querétaro, Querétaro, Mexico
| | - Ellery López-Star
- Instituto Mexicano de Oftalmología (IMO), I.A.P., Circuito Exterior Estadio Corregidora Sn, Centro Sur, Santiago de Querétaro, Querétaro, Mexico
| | - Marlon García-Roa
- Instituto Mexicano de Oftalmología (IMO), I.A.P., Circuito Exterior Estadio Corregidora Sn, Centro Sur, Santiago de Querétaro, Querétaro, Mexico
| | - Van Charles Lansingh
- Instituto Mexicano de Oftalmología (IMO), I.A.P., Circuito Exterior Estadio Corregidora Sn, Centro Sur, Santiago de Querétaro, Querétaro, Mexico
| | - Stéphanie C. Thébault
- Instituto de Neurobiología y Universidad Nacional Autónoma de México (UNAM), Campus UNAM-Juriquilla, Querétaro, Mexico
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Carleton M, Oesch NW. Differences in the spatial fidelity of evoked and spontaneous signals in the degenerating retina. Front Cell Neurosci 2022; 16:1040090. [PMID: 36419935 PMCID: PMC9676928 DOI: 10.3389/fncel.2022.1040090] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Accepted: 10/20/2022] [Indexed: 07/01/2024] Open
Abstract
Vision restoration strategies aim to reestablish vision by replacing the function of lost photoreceptors with optoelectronic hardware or through gene therapy. One complication to these approaches is that retinal circuitry undergoes remodeling after photoreceptor loss. Circuit remodeling following perturbation is ubiquitous in the nervous system and understanding these changes is crucial for treating neurodegeneration. Spontaneous oscillations that arise during retinal degeneration have been well-studied, however, other changes in the spatiotemporal processing of evoked and spontaneous activity have received less attention. Here we use subretinal electrical stimulation to measure the spatial and temporal spread of both spontaneous and evoked activity during retinal degeneration. We found that electrical stimulation synchronizes spontaneous oscillatory activity, over space and through time, thus leading to increased correlations in ganglion cell activity. Intriguingly, we found that spatial selectivity was maintained in rd10 retina for evoked responses, with spatial receptive fields comparable to wt retina. These findings indicate that different biophysical mechanisms are involved in mediating feed forward excitation, and the lateral spread of spontaneous activity in the rd10 retina, lending support toward the possibility of high-resolution vision restoration.
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Affiliation(s)
- Maya Carleton
- Department of Psychology, University of California, San Diego, La Jolla, CA, United States
| | - Nicholas W. Oesch
- Department of Psychology, University of California, San Diego, La Jolla, CA, United States
- Department of Ophthalmology, University of California, San Diego, La Jolla, CA, United States
- The Neurosciences Graduate Program, University of California, San Diego, La Jolla, CA, United States
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8
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Fitzpatrick MJ, Kerschensteiner D. Homeostatic plasticity in the retina. Prog Retin Eye Res 2022; 94:101131. [PMID: 36244950 DOI: 10.1016/j.preteyeres.2022.101131] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 09/25/2022] [Accepted: 09/28/2022] [Indexed: 02/07/2023]
Abstract
Vision begins in the retina, whose intricate neural circuits extract salient features of the environment from the light entering our eyes. Neurodegenerative diseases of the retina (e.g., inherited retinal degenerations, age-related macular degeneration, and glaucoma) impair vision and cause blindness in a growing number of people worldwide. Increasing evidence indicates that homeostatic plasticity (i.e., the drive of a neural system to stabilize its function) can, in principle, preserve retinal function in the face of major perturbations, including neurodegeneration. Here, we review the circumstances and events that trigger homeostatic plasticity in the retina during development, sensory experience, and disease. We discuss the diverse mechanisms that cooperate to compensate and the set points and outcomes that homeostatic retinal plasticity stabilizes. Finally, we summarize the opportunities and challenges for unlocking the therapeutic potential of homeostatic plasticity. Homeostatic plasticity is fundamental to understanding retinal development and function and could be an important tool in the fight to preserve and restore vision.
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Lindner M, Gilhooley MJ, Hughes S, Hankins MW. Optogenetics for visual restoration: From proof of principle to translational challenges. Prog Retin Eye Res 2022; 91:101089. [PMID: 35691861 DOI: 10.1016/j.preteyeres.2022.101089] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 05/17/2022] [Accepted: 05/19/2022] [Indexed: 01/04/2023]
Abstract
Degenerative retinal disorders are a diverse family of diseases commonly leading to irreversible photoreceptor death, while leaving the inner retina relatively intact. Over recent years, innovative gene replacement therapies aiming to halt the progression of certain inherited retinal disorders have made their way into clinics. By rendering surviving retinal neurons light sensitive optogenetic gene therapy now offers a feasible treatment option that can restore lost vision, even in late disease stages and widely independent of the underlying cause of degeneration. Since proof-of-concept almost fifteen years ago, this field has rapidly evolved and a detailed first report on a treated patient has recently been published. In this article, we provide a review of optogenetic approaches for vision restoration. We discuss the currently available optogenetic tools and their relative advantages and disadvantages. Possible cellular targets will be discussed and we will address the question how retinal remodelling may affect the choice of the target and to what extent it may limit the outcomes of optogenetic vision restoration. Finally, we will analyse the evidence for and against optogenetic tool mediated toxicity and will discuss the challenges associated with clinical translation of this promising therapeutic concept.
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Affiliation(s)
- Moritz Lindner
- The Nuffield Laboratory of Ophthalmology, Jules Thorn SCNi, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, OX1 3QU, United Kingdom; Institute of Physiology and Pathophysiology, Department of Neurophysiology, Philipps University, 35037, Marburg, Germany
| | - Michael J Gilhooley
- The Nuffield Laboratory of Ophthalmology, Jules Thorn SCNi, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, OX1 3QU, United Kingdom; The Institute of Ophthalmology, University College London, EC1V 9EL, United Kingdom; Moorfields Eye Hospital, London, EC1V 2PD, United Kingdom
| | - Steven Hughes
- The Nuffield Laboratory of Ophthalmology, Jules Thorn SCNi, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, OX1 3QU, United Kingdom
| | - Mark W Hankins
- The Nuffield Laboratory of Ophthalmology, Jules Thorn SCNi, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, OX1 3QU, United Kingdom.
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Ahn J, Cha S, Choi KE, Kim SW, Yoo Y, Goo YS. Correlated Activity in the Degenerate Retina Inhibits Focal Response to Electrical Stimulation. Front Cell Neurosci 2022; 16:889663. [PMID: 35602554 PMCID: PMC9114441 DOI: 10.3389/fncel.2022.889663] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 04/13/2022] [Indexed: 11/24/2022] Open
Abstract
Retinal prostheses have shown some clinical success in patients with retinitis pigmentosa and age-related macular degeneration. However, even after the implantation of a retinal prosthesis, the patient’s visual acuity is at best less than 20/420. Reduced visual acuity may be explained by a decrease in the signal-to-noise ratio due to the spontaneous hyperactivity of retinal ganglion cells (RGCs) found in degenerate retinas. Unfortunately, abnormal retinal rewiring, commonly observed in degenerate retinas, has rarely been considered for the development of retinal prostheses. The purpose of this study was to investigate the aberrant retinal network response to electrical stimulation in terms of the spatial distribution of the electrically evoked RGC population. An 8 × 8 multielectrode array was used to measure the spiking activity of the RGC population. RGC spikes were recorded in wild-type [C57BL/6J; P56 (postnatal day 56)], rd1 (P56), rd10 (P14 and P56) mice, and macaque [wild-type and drug-induced retinal degeneration (RD) model] retinas. First, we performed a spike correlation analysis between RGCs to determine RGC connectivity. No correlation was observed between RGCs in the control group, including wild-type mice, rd10 P14 mice, and wild-type macaque retinas. In contrast, for the RD group, including rd1, rd10 P56, and RD macaque retinas, RGCs, up to approximately 400–600 μm apart, were significantly correlated. Moreover, to investigate the RGC population response to electrical stimulation, the number of electrically evoked RGC spikes was measured as a function of the distance between the stimulation and recording electrodes. With an increase in the interelectrode distance, the number of electrically evoked RGC spikes decreased exponentially in the control group. In contrast, electrically evoked RGC spikes were observed throughout the retina in the RD group, regardless of the inter-electrode distance. Taken together, in the degenerate retina, a more strongly coupled retinal network resulted in the widespread distribution of electrically evoked RGC spikes. This finding could explain the low-resolution vision in prosthesis-implanted patients.
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Affiliation(s)
- Jungryul Ahn
- Department of Physiology, Chungbuk National University School of Medicine, Cheongju, South Korea
| | - Seongkwang Cha
- Department of Physiology, Chungbuk National University School of Medicine, Cheongju, South Korea
| | - Kwang-Eon Choi
- Department of Ophthalmology, Korea University College of Medicine, Seoul, South Korea
| | - Seong-Woo Kim
- Department of Ophthalmology, Korea University College of Medicine, Seoul, South Korea
- *Correspondence: Seong-Woo Kim,
| | - Yongseok Yoo
- Department of Electronics Engineering, Incheon National University, Incheon, South Korea
- Yongseok Yoo,
| | - Yong Sook Goo
- Department of Physiology, Chungbuk National University School of Medicine, Cheongju, South Korea
- Yong Sook Goo,
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11
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Reh M, Lee M, Zeck G. Expression of Channelrhodopsin‐2 in Rod Bipolar Cells Restores ON and OFF Responses at High Spatial Resolution in Blind Mouse Retina. ADVANCED THERAPEUTICS 2022. [DOI: 10.1002/adtp.202100164] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Miriam Reh
- Neurophysics NMI Natural and Medical Sciences Institute at the University of Tübingen 72770 Reutlingen Germany
- Graduate School of Neural Information Processing/ International Max Planck Research School Tübingen Germany
| | - Meng‐Jung Lee
- Neurophysics NMI Natural and Medical Sciences Institute at the University of Tübingen 72770 Reutlingen Germany
- Graduate School of Neural Information Processing/ International Max Planck Research School Tübingen Germany
| | - Günther Zeck
- Neurophysics NMI Natural and Medical Sciences Institute at the University of Tübingen 72770 Reutlingen Germany
- Institute of Biomedical Electronics TU Wien 1040 Vienna Austria
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12
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Strettoi E, Di Marco B, Orsini N, Napoli D. Retinal Plasticity. Int J Mol Sci 2022; 23:ijms23031138. [PMID: 35163059 PMCID: PMC8835074 DOI: 10.3390/ijms23031138] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 01/17/2022] [Accepted: 01/18/2022] [Indexed: 12/28/2022] Open
Abstract
Brain plasticity is a well-established concept designating the ability of central nervous system (CNS) neurons to rearrange as a result of learning, when adapting to changeable environmental conditions or else while reacting to injurious factors. As a part of the CNS, the retina has been repeatedly probed for its possible ability to respond plastically to a variably altered environment or to pathological insults. However, numerous studies support the conclusion that the retina, outside the developmental stage, is endowed with only limited plasticity, exhibiting, instead, a remarkable ability to maintain a stable architectural and functional organization. Reviewed here are representative examples of hippocampal and cortical paradigms of plasticity and of retinal structural rearrangements found in organization and circuitry following altered developmental conditions or occurrence of genetic diseases leading to neuronal degeneration. The variable rate of plastic changes found in mammalian retinal neurons in different circumstances is discussed, focusing on structural plasticity. The likely adaptive value of maintaining a low level of plasticity in an organ subserving a sensory modality that is dominant for the human species and that requires elevated fidelity is discussed.
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Affiliation(s)
- Enrica Strettoi
- CNR Neuroscience Institute, 56124 Pisa, Italy; (B.D.M.); (N.O.); (D.N.)
- Correspondence: ; Tel.: +39-0503153213
| | - Beatrice Di Marco
- CNR Neuroscience Institute, 56124 Pisa, Italy; (B.D.M.); (N.O.); (D.N.)
- Regional Doctorate School in Neuroscience, Universities of Florence, Pisa and Siena, 50134 Florence, Italy
| | - Noemi Orsini
- CNR Neuroscience Institute, 56124 Pisa, Italy; (B.D.M.); (N.O.); (D.N.)
- Regional Doctorate School in Neuroscience, Universities of Florence, Pisa and Siena, 50134 Florence, Italy
| | - Debora Napoli
- CNR Neuroscience Institute, 56124 Pisa, Italy; (B.D.M.); (N.O.); (D.N.)
- Regional Doctorate School in Neuroscience, Universities of Florence, Pisa and Siena, 50134 Florence, Italy
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13
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Kilicarslan I, Zanetti L, Novelli E, Schwarzer C, Strettoi E, Koschak A. Knockout of Ca V1.3 L-type calcium channels in a mouse model of retinitis pigmentosa. Sci Rep 2021; 11:15146. [PMID: 34312410 PMCID: PMC8313562 DOI: 10.1038/s41598-021-94304-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 07/09/2021] [Indexed: 11/09/2022] Open
Abstract
Retinitis Pigmentosa is a genetically heterogeneous, degenerative retinal disorder characterized by gradual dysfunction and death of photoreceptors, first rods and later cones, and progressive blindness. Studies suggested that application of L-type calcium channel blockers rescues photoreceptors in paradigms related to Ca2+ overflow. To investigate whether Cav1.3 L-type channels have protective effects in the retina, we established a new mouse model by crossing rd10, modeling autosomal-recessive RP, with Cav1.3 deficient mice (rd10/Cav1.3KO). Our immunohistochemical analyses revealed an influence of Cav1.3 channels on the degenerative process of photoreceptors. The absence of Cav1.3 delayed the centre-to-periphery degeneration of rods indicated by a significantly higher number of photoreceptor rows and, consequently, of cones. In accordance with a preserved number of cones we observed a regular row of cone somas in rd10/Cav1.3-KO retinas. Surviving rod photoreceptors maintained synaptic contacts with rod bipolar cells. However, the delay in degeneration was only observed up to postnatal day 45. Although we observed a reduction in the spontaneous oscillatory retinal activity during multielectrode array analyses, measurable functional preservation was lacking in behavioural tests. In conclusion, Cav1.3 channels contribute to photoreceptor degeneration in rd10 retinas but photoreceptor temporary rescue might rather be achieved indirectly through other retinal cell layers.
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Affiliation(s)
- Irem Kilicarslan
- Institute of Pharmacy, Pharmacology and Toxicology, Center for Chemistry and Biomedicine, University of Innsbruck, Innrain 80-82, 6020, Innsbruck, Austria
| | - Lucia Zanetti
- Institute of Pharmacy, Pharmacology and Toxicology, Center for Chemistry and Biomedicine, University of Innsbruck, Innrain 80-82, 6020, Innsbruck, Austria
| | | | - Christoph Schwarzer
- Department of Pharmacology, Medical University of Innsbruck, 6020, Innsbruck, Austria
| | - Enrica Strettoi
- CNR Neuroscience Institute, 56124, Pisa, Italy. .,Istituto Di Neuroscienze CNR, Area della Ricerca, Via Giuseppe Moruzzi 1, 56100, Pisa, Italy.
| | - Alexandra Koschak
- Institute of Pharmacy, Pharmacology and Toxicology, Center for Chemistry and Biomedicine, University of Innsbruck, Innrain 80-82, 6020, Innsbruck, Austria.
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14
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Kare SS, Rountree CM, Troy JB, Finan JD, Saggere L. Neuromodulation using electroosmosis. J Neural Eng 2021; 18:10.1088/1741-2552/ac00d3. [PMID: 33984848 PMCID: PMC8177066 DOI: 10.1088/1741-2552/ac00d3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 05/13/2021] [Indexed: 11/12/2022]
Abstract
Objective.Our laboratory has proposed chemical stimulation of retinal neurons using exogenous glutamate as a biomimetic strategy for treating vision loss caused by photoreceptor (PR) degenerative diseases. Although our previousin-vitrostudies using pneumatic actuation indicate that chemical retinal stimulation is achievable, an actuation technology that is amenable to microfabrication, as needed for anin-vivoimplantable device, has yet to be realized. In this study, we sought to evaluate electroosmotic flow (EOF) as a mechanism for delivering small quantities of glutamate to the retina. EOF has great potential for miniaturization.Approach.An EOF device to dispense small quantities of glutamate was constructed and its ability to drive retinal output tested in anin-vitropreparation of PR degenerate rat retina.Main results.We built and tested an EOF microfluidic system, with 3D printed and off-the-shelf components, capable of injecting small volumes of glutamate in a pulsatile fashion when a low voltage control signal was applied. With this device, we produced excitatory and inhibitory spike rate responses in PR degenerate rat retinae. Glutamate evoked spike rate responses were also observed to be voltage-dependent and localized to the site of injection.Significance.The EOF device performed similarly to a previously tested conventional pneumatic microinjector as a means of chemically stimulating the retina while eliminating the moving plunger of the pneumatic microinjector that would be difficult to miniaturize and parallelize. Although not implantable, the prototype device presented here as a proof of concept indicates that a retinal prosthetic based on EOF-driven chemical stimulation is a viable and worthwhile goal. EOF should have similar advantages for controlled dispensing of charged neurochemicals at any neural interface.
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Affiliation(s)
- Sai Siva Kare
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL, United States of America
| | - Corey M Rountree
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL, United States of America
| | - John B Troy
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, United States of America
| | - John D Finan
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL, United States of America
| | - Laxman Saggere
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL, United States of America
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15
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Telias M, Nawy S, Kramer RH. Degeneration-Dependent Retinal Remodeling: Looking for the Molecular Trigger. Front Neurosci 2021; 14:618019. [PMID: 33390897 PMCID: PMC7775662 DOI: 10.3389/fnins.2020.618019] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 11/27/2020] [Indexed: 11/23/2022] Open
Abstract
Vision impairment and blindness in humans are most frequently caused by the degeneration and loss of photoreceptor cells in the outer retina, as is the case for age-related macular degeneration, retinitis pigmentosa, retinal detachment and many other diseases. While inner retinal neurons survive degeneration, they undergo fundamental pathophysiological changes, collectively known as “remodeling.” Inner retinal remodeling downstream to photoreceptor death occurs across mammalian retinas from mice to humans, independently of the cause of degeneration. It results in pervasive spontaneous hyperactivity and membrane hyperpermeability in retinal ganglion cells, which funnel all retinal signals to the brain. Remodeling reduces light detection in vision-impaired patients and precludes meaningful vision restoration in blind individuals. In this review, we summarize current hypotheses proposed to explain remodeling and their potential medical significance highlighting the important role played by retinoic acid and its receptor.
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Affiliation(s)
- Michael Telias
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, United States
| | - Scott Nawy
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, United States
| | - Richard H Kramer
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, United States.,Helen Wills Neuroscience Institute, University of California, Berkeley, CA, United States
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16
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Li C, Tian Y, Yao A, Zha X, Zhang J, Tao Y. Intravitreal Delivery of Melatonin Is Protective Against the Photoreceptor Loss in Mice: A Potential Therapeutic Strategy for Degenerative Retinopathy. Front Pharmacol 2020; 10:1633. [PMID: 32116667 PMCID: PMC7028754 DOI: 10.3389/fphar.2019.01633] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 12/13/2019] [Indexed: 12/12/2022] Open
Abstract
Melatonin is a circadian hormone with potent cytoprotective effects. Retinitis pigmentosa (RP) comprises a heterogeneous group of inherent retinopathies that characterized by the photoreceptor death in bilateral eyes. The N-methyl-N-nitrosourea (MNU) administered mouse is a type of chemically induced RP model with rapid progressive rate. We intend to study the melatonin mediated effects on the MNU administered mice. Melatonin was delivered into the vitreous body of the MNU administered mice. Subsequently, the melatonin treated mice were subjected to histological analysis, optokinetic behavior tests, spectral-domain optical coherence tomography (SD-OCT), and electroretinogram (ERG) examination. Multi-electrodes array (MEA) was used to analyze the status of visual signal transmission within retinal circuits. Biochemical analysis was performed to quantify the expression levels of antioxidative enzymes, oxidative stress markers, and apoptotic factors in the retinas. The intravitreal injection of melatonin ameliorated effectively the MNU induced photoreceptor degeneration. Melatonin therapy mitigated the spontaneous firing response, and preserved the basic configurations of visual signal pathway in MNU administered mice. MEA is effective to evaluate the pharmacological effects on retina. Of note, the cone photoreceptors in degenerative retinas were rescued efficiently by melatonin therapy. Melatonin afforded these protective effects by modulating the apoptotic cascades and alleviating the oxidative stress. These findings suggest that melatonin could act as an alternative treatment for degenerative retinopathy. Melatonin might be used in combination with other therapeutic approaches to alleviate the photoreceptor loss and preserve the visual function of RP patients.
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Affiliation(s)
- Chong Li
- Department of Neurosurgery, PLA General Hospital, Beijing, China
| | - Yi Tian
- Department of Oncology, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Anhui Yao
- Department of Neurosurgery, PLA General Hospital, Beijing, China
| | - Xiaobing Zha
- Department of Rehabilitation, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Jianbin Zhang
- Department of Occupational and Environmental Health, Ministry of Education Key Lab of Hazard Assessment and Control in Special Operational Environment, School of Public Health, Fourth Military Medical University, Xi'an, China
| | - Ye Tao
- Department of Ophthalmology, Henan Provincial People’s Hospital, Zhengzhou University, People’s Hospital, Zhengzhou, China
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17
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Pfeiffer RL, Marc RE, Jones BW. Persistent remodeling and neurodegeneration in late-stage retinal degeneration. Prog Retin Eye Res 2020; 74:100771. [PMID: 31356876 PMCID: PMC6982593 DOI: 10.1016/j.preteyeres.2019.07.004] [Citation(s) in RCA: 95] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 07/15/2019] [Accepted: 07/18/2019] [Indexed: 02/06/2023]
Abstract
Retinal remodeling is a progressive series of negative plasticity revisions that arise from retinal degeneration, and are seen in retinitis pigmentosa, age-related macular degeneration and other forms of retinal disease. These processes occur regardless of the precipitating event leading to degeneration. Retinal remodeling then culminates in a late-stage neurodegeneration that is indistinguishable from progressive central nervous system (CNS) proteinopathies. Following long-term deafferentation from photoreceptor cell death in humans, and long-lived animal models of retinal degeneration, most retinal neurons reprogram, then die. Glial cells reprogram into multiple anomalous metabolic phenotypes. At the same time, survivor neurons display degenerative inclusions that appear identical to progressive CNS neurodegenerative disease, and contain aberrant α-synuclein (α-syn) and phosphorylated α-syn. In addition, ultrastructural analysis indicates a novel potential mechanism for misfolded protein transfer that may explain how proteinopathies spread. While neurodegeneration poses a barrier to prospective retinal interventions that target primary photoreceptor loss, understanding the progression and time-course of retinal remodeling will be essential for the establishment of windows of therapeutic intervention and appropriate tuning and design of interventions. Finally, the development of protein aggregates and widespread neurodegeneration in numerous retinal degenerative diseases positions the retina as a ideal platform for the study of proteinopathies, and mechanisms of neurodegeneration that drive devastating CNS diseases.
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Affiliation(s)
- Rebecca L Pfeiffer
- Dept of Ophthalmology, Moran Eye Center, University of Utah, Salt Lake City, UT, USA; Interdepartmental Program in Neuroscience, University of Utah, Salt Lake City, UT, USA.
| | - Robert E Marc
- Dept of Ophthalmology, Moran Eye Center, University of Utah, Salt Lake City, UT, USA; Interdepartmental Program in Neuroscience, University of Utah, Salt Lake City, UT, USA
| | - Bryan William Jones
- Dept of Ophthalmology, Moran Eye Center, University of Utah, Salt Lake City, UT, USA; Interdepartmental Program in Neuroscience, University of Utah, Salt Lake City, UT, USA.
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18
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Stefanov A, Novelli E, Strettoi E. Inner retinal preservation in the photoinducible I307N rhodopsin mutant mouse, a model of autosomal dominant retinitis pigmentosa. J Comp Neurol 2019; 528:1502-1522. [PMID: 31811649 PMCID: PMC7187456 DOI: 10.1002/cne.24838] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 12/03/2019] [Accepted: 12/03/2019] [Indexed: 12/20/2022]
Abstract
Rod‐cone degenerations, for example, retinitis pigmentosa are leading causes of blindness worldwide. Despite slow disease progression in humans, vision loss is inevitable; therefore, development of vision restoration strategies is crucial. Among others, promising approaches include optogenetics and prosthetic implants, which aim to bypass lost photoreceptors (PRs). Naturally, the efficacy of these therapeutic strategies will depend on inner retinal structural and functional preservation. The present study shows that in photoinducible I307N rhodopsin mice (Translational Vision Research Model 4 [Tvrm4]), a 12k lux light exposure eliminates PRs in the central retina in 1 week, but interneurons and their synapses are maintained for as long as 9 weeks postinduction. Despite bipolar cell dendritic retraction and moderate loss of horizontal cells, the survival rate of various cell types is very high. Significant preservation of conventional synapses and gap junctions in the inner plexiform layer is also observed. We found the number of synaptic ribbons to gradually decline and their ultrastructure to become transiently abnormal, although based on our findings intrinsic retinal architecture is maintained despite complete loss of PRs. Unlike common rodent models of PR degeneration, where the disease phenotype often interferes with retinal development, in Tvrm4 mice, the degenerative process can be induced after retinal development is complete. This time course more closely mimics the timing of disease onset in affected patients. Stability of the inner retina found in these mutants 2 months after PR degeneration suggests moderate, stereotyped remodeling in the early stages of the human disease and represents a promising finding for prompt approaches of vision restoration.
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Affiliation(s)
- Antonia Stefanov
- Institute of Neuroscience, Italian National Research Council - CNR, Pisa, Italy.,Regional Doctoral School of Neuroscience, University of Florence, Florence, Italy
| | - Elena Novelli
- Institute of Neuroscience, Italian National Research Council - CNR, Pisa, Italy
| | - Enrica Strettoi
- Institute of Neuroscience, Italian National Research Council - CNR, Pisa, Italy
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19
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Photopharmacologic Vision Restoration Reduces Pathological Rhythmic Field Potentials in Blind Mouse Retina. Sci Rep 2019; 9:13561. [PMID: 31537864 PMCID: PMC6753071 DOI: 10.1038/s41598-019-49999-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 09/03/2019] [Indexed: 11/28/2022] Open
Abstract
Photopharmacology has yielded compounds that have potential to restore impaired visual responses resulting from outer retinal degeneration diseases such as retinitis pigmentosa. Here we evaluate two photoswitchable azobenzene ion channel blockers, DAQ and DAA for vision restoration. DAQ exerts its effect primarily on RGCs, whereas DAA induces light-dependent spiking primarily through amacrine cell activation. Degeneration-induced local field potentials remain a major challenge common to all vision restoration approaches. These 5–10 Hz rhythmic potentials increase the background firing rate of retinal ganglion cells (RGCs) and overlay the stimulated response, thereby reducing signal-to-noise ratio. Along with the bipolar cell-selective photoswitch DAD and second-generation RGC-targeting photoswitch PhENAQ, we investigated the effects of DAA and DAQ on rhythmic local field potentials (LFPs) occurring in the degenerating retina. We found that photoswitches targeting neurons upstream of RGCs, DAA (amacrine cells) and DAD (bipolar cells) suppress the frequency of LFPs, while DAQ and PhENAQ (RGCs) had negligible effects on frequency or spectral power of LFPs. Taken together, these results demonstrate remarkable diversity of cell-type specificity of photoswitchable channel blockers in the retina and suggest that specific compounds may counter rhythmic LFPs to produce superior signal-to-noise characteristics in vision restoration.
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20
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Stasheff SF. Clinical Impact of Spontaneous Hyperactivity in Degenerating Retinas: Significance for Diagnosis, Symptoms, and Treatment. Front Cell Neurosci 2018; 12:298. [PMID: 30250425 PMCID: PMC6139326 DOI: 10.3389/fncel.2018.00298] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Accepted: 08/17/2018] [Indexed: 11/23/2022] Open
Abstract
Hereditary retinal degenerations result from varied pathophysiologic mechanisms, all ultimately characterized by photoreceptor dysfunction and death. Hence, much research on these diseases has concentrated on the outer retina. Over the past decade or so increasing attention has focused on concomitant changes in complex inner retinal neural circuits that process visual signals for transmission to the brain. One striking abnormality develops before the ultimately profound anatomic disruption of the inner retina. Highly elevated spontaneous activity was first demonstrated in central nervous system visual centers in vivo by Dräger and Hubel (1978), and subsequently has been confirmed in vitro, now in multiple animal models and by multiple investigators (see other contributions to this Research Topic). What evidence exists that this phenomenon occurs in human patients with retinal degeneration, and what is the ultimate effect of spontaneous hyperactivity in the output neurons, the retinal ganglion cells? Here I summarize abnormalities of visual perception among patients with retinal degeneration that may arise from hyperactivity. Next, I consider the disruption of neural encoding and anatomic connectivity that may result within the retina and in downstream visual centers of the brain. I then consider how specific characteristics of hyperactivity may distinguish various forms or stages of retinal degeneration, potentially helping in the near future to refine diagnosis and/or treatment choices for different patients. Finally, I review how consideration of these features may help optimize pharmacologic, gene, stem cell, prosthetic or other therapies to forestall visual loss or restore sight.
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Affiliation(s)
- Steven F Stasheff
- Center for Neuroscience and Behavioral Medicine, Gilbert Family Neurofibromatosis Institute, Children's National Health System, Washington, DC, United States.,Visual Neurophysiology, Neuro-ophthalmology and Pediatric Neurology, Retinal Neurophysiology Section, National Eye Institute, Bethesda, MD, United States
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21
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Different Activity Patterns in Retinal Ganglion Cells of TRPM1 and mGluR6 Knockout Mice. BIOMED RESEARCH INTERNATIONAL 2018; 2018:2963232. [PMID: 29854741 PMCID: PMC5964425 DOI: 10.1155/2018/2963232] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Accepted: 02/11/2018] [Indexed: 12/28/2022]
Abstract
TRPM1, the first member of the melanoma-related transient receptor potential (TRPM) subfamily, is the visual transduction channel downstream of metabotropic glutamate receptor 6 (mGluR6) on retinal ON bipolar cells (BCs). Human TRPM1 mutations are associated with congenital stationary night blindness (CSNB). In both TRPM1 and mGluR6 KO mouse retinas, OFF but not ON BCs respond to light stimulation. Here we report an unexpected difference between TRPM1 knockout (KO) and mGluR6 KO mouse retinas. We used a multielectrode array (MEA) to record spiking in retinal ganglion cells (RGCs). We found spontaneous oscillations in TRPM1 KO retinas, but not in mGluR6 KO retinas. We performed a structural analysis on the synaptic terminals of rod ON BCs. Intriguingly, rod ON BC terminals were significantly smaller in TRPM1 KO retinas than in mGluR6 KO retinas. These data suggest that a deficiency of TRPM1, but not of mGluR6, in rod ON bipolar cells may affect synaptic terminal maturation. We speculate that impaired signaling between rod BCs and AII amacrine cells (ACs) leads to spontaneous oscillations. TRPM1 and mGluR6 are both essential components in the signaling pathway from photoreceptors to ON BC dendrites, yet they differ in their effects on the BC terminal and postsynaptic circuitry.
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22
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Taniguchi K, Koike C, Kitano K. [A Potential Mechanism for Spontaneous Oscillation in the Abnormal Retina]. YAKUGAKU ZASSHI 2018; 138:685-692. [PMID: 29710014 DOI: 10.1248/yakushi.17-00200-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Rhythmic neural activities are observed in many brain regions, and these are considered to play an important role in neural information processing. On the other hand, distinct rhythmic neural activities emerge under several pathological conditions, suggesting that rhythmic neural activity has a close relation to brain function and dysfunction. In many pathological cases, the intrinsic property of unusual rhythm generation in a neuron or a neuronal network is prevented under normal conditions, but released by the pathological condition. Therefore, it may be useful to explore which conditions determine rhythm generation in order to understand the mechanisms of brain function/dysfunction. The pathological retina in retinal degeneration exhibits rhythmic neural activity not observed in the healthy retina. In this review, we first provide a brief introduction to the possible mechanisms of rhythm generation in a neural system. Then we introduce experimental evidence of rhythm generation in the pathological retina, as well as two hypotheses regarding this mechanism. Finally, we raise several issues to be solved for the further understanding of pathological rhythm generation.
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Affiliation(s)
- Kanako Taniguchi
- Graduate School of Information Science and Engineering, Ritsumeikan University
| | - Chieko Koike
- Graduate School of Life Sciences, Ritsumeikan University.,College of Pharmaceutical Sciences, Ritsumeikan University.,Center for Systems Vision Science, Research Organization of Science and Technology, Ritsumeikan University
| | - Katsunori Kitano
- College of Information Science and Engineering, Ritsumeikan University
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23
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Iraha S, Tu HY, Yamasaki S, Kagawa T, Goto M, Takahashi R, Watanabe T, Sugita S, Yonemura S, Sunagawa GA, Matsuyama T, Fujii M, Kuwahara A, Kishino A, Koide N, Eiraku M, Tanihara H, Takahashi M, Mandai M. Establishment of Immunodeficient Retinal Degeneration Model Mice and Functional Maturation of Human ESC-Derived Retinal Sheets after Transplantation. Stem Cell Reports 2018; 10:1059-1074. [PMID: 29503091 PMCID: PMC5918611 DOI: 10.1016/j.stemcr.2018.01.032] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Revised: 01/28/2018] [Accepted: 01/29/2018] [Indexed: 12/21/2022] Open
Abstract
Increasing demand for clinical retinal degeneration therapies featuring human ESC/iPSC-derived retinal tissue and cells warrants proof-of-concept studies. Here, we established two mouse models of end-stage retinal degeneration with immunodeficiency, NOG-rd1-2J and NOG-rd10, and characterized disease progress and immunodeficient status. We also transplanted human ESC-derived retinal sheets into NOG-rd1-2J and confirmed their long-term survival and maturation of the structured graft photoreceptor layer, without rejection or tumorigenesis. We recorded light responses from the host ganglion cells using a multi-electrode array system; this result was consistent with whole-mount immunostaining suggestive of host-graft synapse formation at the responding sites. This study demonstrates an application of our mouse models and provides a proof of concept for the clinical use of human ESC-derived retinal sheets. Two mouse models of immunodeficient end-stage retinal degeneration were established Immunodeficient host permitted transplantation of human ESC-derived retinal sheets Transplanted human ESC-derived retinal sheets survived long term and maturated After transplantation, light responses were recorded from the degenerated host retina
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Affiliation(s)
- Satoshi Iraha
- Laboratory for Retinal Regeneration, Center for Developmental Biology, RIKEN, Kobe, Hyogo 650-0047, Japan; Department of Ophthalmology, Faculty of Life Sciences, Kumamoto University, Kumamoto 860-8556, Japan; Application Biology and Regenerative Medicine, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan
| | - Hung-Ya Tu
- Laboratory for Retinal Regeneration, Center for Developmental Biology, RIKEN, Kobe, Hyogo 650-0047, Japan
| | - Suguru Yamasaki
- Laboratory for Retinal Regeneration, Center for Developmental Biology, RIKEN, Kobe, Hyogo 650-0047, Japan; Regenerative and Cellular Medicine Office, Sumitomo Dainippon Pharma Co., Ltd., Kobe, Hyogo 650-0047, Japan
| | - Takahiro Kagawa
- Central Institute for Experimental Animals, Animal Resources and Technical Research Center, Kawasaki, Kanagawa 210-0821, Japan
| | - Motohito Goto
- Central Institute for Experimental Animals, Animal Resources and Technical Research Center, Kawasaki, Kanagawa 210-0821, Japan
| | - Riichi Takahashi
- Central Institute for Experimental Animals, Animal Resources and Technical Research Center, Kawasaki, Kanagawa 210-0821, Japan
| | - Takehito Watanabe
- Laboratory for Retinal Regeneration, Center for Developmental Biology, RIKEN, Kobe, Hyogo 650-0047, Japan
| | - Sunao Sugita
- Laboratory for Retinal Regeneration, Center for Developmental Biology, RIKEN, Kobe, Hyogo 650-0047, Japan
| | - Shigenobu Yonemura
- Ultrastructural Research Team, RIKEN Center for Life Science Technologies., Kobe, Hyogo 650-0047, Japan; Department of Cell Biology, Tokushima University Graduate School of Medical Science, Tokushima 770-8503, Japan
| | - Genshiro A Sunagawa
- Laboratory for Retinal Regeneration, Center for Developmental Biology, RIKEN, Kobe, Hyogo 650-0047, Japan
| | - Take Matsuyama
- Laboratory for Retinal Regeneration, Center for Developmental Biology, RIKEN, Kobe, Hyogo 650-0047, Japan
| | - Momo Fujii
- Laboratory for Retinal Regeneration, Center for Developmental Biology, RIKEN, Kobe, Hyogo 650-0047, Japan
| | - Atsushi Kuwahara
- Regenerative and Cellular Medicine Office, Sumitomo Dainippon Pharma Co., Ltd., Kobe, Hyogo 650-0047, Japan
| | - Akiyoshi Kishino
- Regenerative and Cellular Medicine Office, Sumitomo Dainippon Pharma Co., Ltd., Kobe, Hyogo 650-0047, Japan
| | - Naoshi Koide
- Laboratory for Retinal Regeneration, Center for Developmental Biology, RIKEN, Kobe, Hyogo 650-0047, Japan
| | - Mototsugu Eiraku
- Laboratory for in vitro Histogenesis, RIKEN Center for Developmental Biology, Kobe, Hyogo 650-0047, Japan
| | - Hidenobu Tanihara
- Department of Ophthalmology, Faculty of Life Sciences, Kumamoto University, Kumamoto 860-8556, Japan
| | - Masayo Takahashi
- Laboratory for Retinal Regeneration, Center for Developmental Biology, RIKEN, Kobe, Hyogo 650-0047, Japan; Application Biology and Regenerative Medicine, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan
| | - Michiko Mandai
- Laboratory for Retinal Regeneration, Center for Developmental Biology, RIKEN, Kobe, Hyogo 650-0047, Japan; RIKEN Program for Drug Discovery and Medical Technology Platforms (DMP), Kobe, Hyogo 650-0047, Japan.
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24
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Rountree CM, Troy JB, Saggere L. Methodology for Biomimetic Chemical Neuromodulation of Rat Retinas with the Neurotransmitter Glutamate In Vitro. J Vis Exp 2017. [PMID: 29286422 DOI: 10.3791/56645] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Photoreceptor degenerative diseases cause irreparable blindness through the progressive loss of photoreceptor cells in the retina. Retinal prostheses are an emerging treatment for photoreceptor degenerative diseases that seek to restore vision by artificially stimulating the surviving retinal neurons in the hope of eliciting comprehensible visual perception in patients. Current retinal prostheses have demonstrated success in restoring limited vision to patients using an array of electrodes to electrically stimulate the retina but face substantial physical barriers in restoring high acuity, natural vision to patients. Chemical neurostimulation using native neurotransmitters is a biomimetic alternative to electrical stimulation and could bypass the fundamental limitations associated with retinal prostheses using electrical neurostimulation. Specifically, chemical neurostimulation has the potential to restore more natural vision with comparable or better visual acuities to patients by injecting very small quantities of neurotransmitters, the same natural agents of communication used by retinal chemical synapses, at much finer resolution than current electrical prostheses. However, as a relatively unexplored stimulation paradigm, there is no established protocol for achieving chemical stimulation of the retina in vitro. The purpose of this work is to provide a detailed framework for accomplishing chemical stimulation of the retina for investigators who wish to study the potential of chemical neuromodulation of the retina or similar neural tissues in vitro. In this work, we describe the experimental setup and methodology for eliciting retinal ganglion cell (RGC) spike responses similar to visual light responses in wild-type and photoreceptor-degenerated wholemount rat retinas by injecting controlled volumes of the neurotransmitter glutamate into the subretinal space using glass micropipettes and a custom multiport microfluidic device. This methodology and protocol are general enough to be adapted for neuromodulation using other neurotransmitters or even other neural tissues.
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Affiliation(s)
- Corey M Rountree
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago
| | - John B Troy
- Department of Biomedical Engineering, Northwestern University
| | - Laxman Saggere
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago;
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25
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Gargini C, Novelli E, Piano I, Biagioni M, Strettoi E. Pattern of retinal morphological and functional decay in a light-inducible, rhodopsin mutant mouse. Sci Rep 2017; 7:5730. [PMID: 28720880 PMCID: PMC5516022 DOI: 10.1038/s41598-017-06045-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 06/06/2017] [Indexed: 02/02/2023] Open
Abstract
Hallmarks of Retinitis Pigmentosa (RP), a family of genetic diseases, are a typical rod-cone-degeneration with initial night blindness and loss of peripheral vision, followed by decreased daylight sight and progressive visual acuity loss up to legal blindness. Great heterogeneity in nature and function of mutated genes, variety of mutations for each of them, variability in phenotypic appearance and transmission modality contribute to make RP a still incurable disease. Translational research relies on appropriate animal models mimicking the genetic and phenotypic diversity of the human pathology. Here, we provide a systematic, morphological and functional analysis of RhoTvrm4/Rho+ rhodopsin mutant mice, originally described in 2010 and portraying several features of common forms of autosomal dominant RP caused by gain-of-function mutations. These mice undergo photoreceptor degeneration only when exposed briefly to strong, white light and allow controlled timing of induction of rod and cone death, which therefore can be elicited in adult animals, as observed in human RP. The option to control severity and retinal extent of the phenotype by regulating intensity and duration of the inducing light opens possibilities to exploit this model for multiple experimental purposes. Altogether, the unique features of this mutant make it an excellent resource for retinal degeneration research.
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Affiliation(s)
| | | | - Ilaria Piano
- Department of Pharmacy, University of Pisa, Pisa, Italy
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26
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Yu WQ, Grzywacz NM, Lee EJ, Field GD. Cell type-specific changes in retinal ganglion cell function induced by rod death and cone reorganization in rats. J Neurophysiol 2017; 118:434-454. [PMID: 28424296 PMCID: PMC5506261 DOI: 10.1152/jn.00826.2016] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 04/17/2017] [Accepted: 04/17/2017] [Indexed: 02/02/2023] Open
Abstract
We have determined the impact of rod death and cone reorganization on the spatiotemporal receptive fields (RFs) and spontaneous activity of distinct retinal ganglion cell (RGC) types. We compared RGC function between healthy and retinitis pigmentosa (RP) model rats (S334ter-3) at a time when nearly all rods were lost but cones remained. This allowed us to determine the impact of rod death on cone-mediated visual signaling, a relevant time point because the diagnosis of RP frequently occurs when patients are nightblind but daytime vision persists. Following rod death, functionally distinct RGC types persisted; this indicates that parallel processing of visual input remained largely intact. However, some properties of cone-mediated responses were altered ubiquitously across RGC types, such as prolonged temporal integration and reduced spatial RF area. Other properties changed in a cell type-specific manner, such as temporal RF shape (dynamics), spontaneous activity, and direction selectivity. These observations identify the extent of functional remodeling in the retina following rod death but before cone loss. They also indicate new potential challenges to restoring normal vision by replacing lost rod photoreceptors.NEW & NOTEWORTHY This study provides novel and therapeutically relevant insights to retinal function following rod death but before cone death. To determine changes in retinal output, we used a large-scale multielectrode array to simultaneously record from hundreds of retinal ganglion cells (RGCs). These recordings of large-scale neural activity revealed that following the death of all rods, functionally distinct RGCs remain. However, the receptive field properties and spontaneous activity of these RGCs are altered in a cell type-specific manner.
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Affiliation(s)
- Wan-Qing Yu
- Neuroscience Graduate Program, University of Southern California, Los Angeles, California
| | - Norberto M Grzywacz
- Neuroscience Graduate Program, University of Southern California, Los Angeles, California.,Department of Biomedical Engineering, University of Southern California, Los Angeles, California.,Department of Electrical Engineering, University of Southern California, Los Angeles, California.,Department of Neuroscience, Department of Physics, and Graduate School of Arts and Sciences, Georgetown University, Washington, District of Columbia
| | - Eun-Jin Lee
- Department of Biomedical Engineering, University of Southern California, Los Angeles, California.,Mary D. Allen Laboratory for Vision Research, USC Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, California; and
| | - Greg D Field
- Department of Neurobiology, Duke University School of Medicine, Durham, North Carolina
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27
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Stutzki H, Helmhold F, Eickenscheidt M, Zeck G. Subretinal electrical stimulation reveals intact network activity in the blind mouse retina. J Neurophysiol 2016; 116:1684-1693. [PMID: 27486110 DOI: 10.1152/jn.01095.2015] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 07/12/2016] [Indexed: 11/22/2022] Open
Abstract
Retinal degeneration (rd) leads to progressive photoreceptor cell death, resulting in vision loss. Stimulation of the inner-retinal neurons by neuroprosthetic implants is one of the clinically approved vision-restoration strategies, providing basic visual percepts to blind patients. However, little is understood as to what degree the degenerating retinal circuitry and the resulting aberrant hyperactivity may prevent the stimulation of physiological electrical activity. Therefore, we electrically stimulated ex vivo retinas from wild-type (wt; C57BL/6J) and blind (rd10 and rd1) mice using an implantable subretinal microchip and simultaneously recorded and analyzed the retinal ganglion cell (RGC) output with a flexible microelectrode array. We found that subretinal anodal stimulation of the rd10 retina and wt retina evoked similar spatiotemporal RGC-spiking patterns. In both retinas, electrically stimulated ON and a small percentage of OFF RGC responses were detected. The spatial selectivity of the retinal network to electrical stimuli reveals an intact underlying network with a median receptive-field center of 350 μm in both retinas. An antagonistic surround is activated by stimulation with large electrode fields. However, in rd10 and to a higher percentage, in rd1 retinas, rhythmic and spatially unconfined RGC patterns were evoked by anodal or by cathodal electrical stimuli. Our findings demonstrate that the surviving retinal circuitry in photoreceptor-degenerated retinas is preserved in a way allowing for the stimulation of temporally diverse and spatially confined RGC activity. Future vision restoration strategies can build on these results but need to avoid evoking the easily inducible rhythmic activity in some retinal circuits.
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Affiliation(s)
- Henrike Stutzki
- Natural and Medical Sciences Institute at the University of Tübingen, Reutlingen, Germany; and Graduate School of Neural and Behavioural Sciences/International Max Planck Research School, Tübingen, Germany
| | - Florian Helmhold
- Natural and Medical Sciences Institute at the University of Tübingen, Reutlingen, Germany; and
| | - Max Eickenscheidt
- Natural and Medical Sciences Institute at the University of Tübingen, Reutlingen, Germany; and
| | - Günther Zeck
- Natural and Medical Sciences Institute at the University of Tübingen, Reutlingen, Germany; and
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28
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Zeck G. Aberrant Activity in Degenerated Retinas Revealed by Electrical Imaging. Front Cell Neurosci 2016; 10:25. [PMID: 26903810 PMCID: PMC4758270 DOI: 10.3389/fncel.2016.00025] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Accepted: 01/25/2016] [Indexed: 02/05/2023] Open
Abstract
In this review, I present and discuss the current understanding of aberrant electrical activity found in the ganglion cell layer (GCL) of rod-degenerated (rd) mouse retinas. The reported electrophysiological properties revealed by electrical imaging using high-density microelectrode arrays can be subdivided between spiking activity originating from retinal ganglion cells (RGCs) and local field potentials (LFPs) reflecting strong trans-membrane currents within the GCL. RGCs in rd retinas show increased and rhythmic spiking compared to age-matched wild-type retinas. Fundamental spiking frequencies range from 5 to 15 Hz in various mouse models. The rhythmic RGC spiking is driven by a presynaptic network comprising AII amacrine and bipolar cells. In the healthy retina this rhythm-generating circuit is inhibited by photoreceptor input. A unique physiological feature of rd retinas is rhythmic LFP manifested as spatially-restricted low-frequency (5-15 Hz) voltage changes. Their spatiotemporal characterization revealed propagation and correlation with RGC spiking. LFPs rely on gap-junctional coupling and are shaped by glycinergic and by GABAergic transmission. The aberrant RGC spiking and LFPs provide a simple readout of the functionality of the remaining retinal circuitry which can be used in the development of improved vision restoration strategies.
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Affiliation(s)
- Günther Zeck
- Neurochip Research Group, Natural and Medical Sciences Institute at the University of Tübingen Reutlingen, Germany
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Abstract
Up to 15 years ago, bibliographic searches based on keywords such as “photoreceptor degeneration, inner retina” or “photoreceptor degeneration, second order neurons” returned only a handful of papers, as the field was dominated by the general assumption that retinal degeneration had direct effects on the sole populations of rods and cones. Since then, a number of studies have been dedicated to understanding the process of gradual morphological, molecular, and functional changes arising among cells located in the inner retina (comprising neurons, glia, and blood vessels), that is to say “beyond” photoreceptors. General aspects of this progression of biological rearrangements, now referred to as “remodeling”, were revealed and demonstrated to accompany consistently photoreceptor loss, independently from the underlying cause of degeneration. Recurrent features of remodeling are summarized here, to provide a general frame for to the various analytical descriptions and reviews contributed by the articles in the issue (among others, see Euler and Schubert, 2015; Soto and Kerschensteiner, 2015, this issue).
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Affiliation(s)
- Enrica Strettoi
- Italian National Research Council, Neuroscience Institute Pisa, Italy
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