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Richardson RT, Ibbotson MR, Thompson AC, Wise AK, Fallon JB. Optical stimulation of neural tissue. Healthc Technol Lett 2020; 7:58-65. [PMID: 32754339 PMCID: PMC7353819 DOI: 10.1049/htl.2019.0114] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 05/08/2020] [Accepted: 05/15/2020] [Indexed: 12/23/2022] Open
Abstract
Electrical stimulation has been used for decades in devices such as pacemakers, cochlear implants and more recently for deep brain and retinal stimulation and electroceutical treatment of disease. However, current spread from the electrodes limits the precision of neural activation, leading to a low quality therapeutic outcome or undesired side-effects. Alternative methods of neural stimulation such as optical stimulation offer the potential to deliver higher spatial resolution of neural activation. Direct optical stimulation is possible with infrared light, while visible light can be used to activate neurons if the neural tissue is genetically modified with a light sensitive ion channel. Experimentally, both methods have resulted in highly precise stimulation with little spread of activation at least in the cochlea, each with advantages and disadvantages. Infrared neural stimulation does not require modification of the neural tissue, but has very high power requirements. Optogenetics can achieve precision of activation with lower power, but only in conjunction with targeted insertion of a light sensitive ion channel into the nervous system via gene therapy. This review will examine the advantages and limitations of optical stimulation of neural tissue, using the cochlea as an exemplary model and recent developments for retinal and deep brain stimulation.
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Affiliation(s)
- Rachael Theresa Richardson
- Bionics Institute, Melbourne 3002, Australia.,University of Melbourne, Medical Bionics Department, Melbourne, 3002, Australia.,University of Melbourne, Department of Surgery (Otolaryngology), Melbourne, 3002, Australia
| | - Michael R Ibbotson
- National Vision Research Institute, Australian College of Optometry, and Department of Optometry and Vision Science, University of Melbourne, Melbourne, Australia
| | | | - Andrew K Wise
- Bionics Institute, Melbourne 3002, Australia.,University of Melbourne, Medical Bionics Department, Melbourne, 3002, Australia.,University of Melbourne, Department of Surgery (Otolaryngology), Melbourne, 3002, Australia
| | - James B Fallon
- Bionics Institute, Melbourne 3002, Australia.,University of Melbourne, Medical Bionics Department, Melbourne, 3002, Australia.,University of Melbourne, Department of Surgery (Otolaryngology), Melbourne, 3002, Australia
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Dhakal KR, Walters S, McGregor JE, Schwarz C, Strazzeri JM, Aboualizadeh E, Bateman B, Huxlin KR, Hunter JJ, Williams DR, Merigan WH. Localized Photoreceptor Ablation Using Femtosecond Pulses Focused With Adaptive Optics. Transl Vis Sci Technol 2020; 9:16. [PMID: 32832223 PMCID: PMC7414617 DOI: 10.1167/tvst.9.7.16] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 04/09/2020] [Indexed: 02/03/2023] Open
Abstract
Purpose The development of new approaches to human vision restoration could be greatly accelerated with the use of nonhuman primate models; however, there is a paucity of primate models of outer retina degeneration with good spatial localization. To limit ablation to the photoreceptors, we developed a new approach that uses a near-infrared ultrafast laser, focused using adaptive optics, to concentrate light in a small focal volume within the retina. Methods In the eyes of eight anesthetized macaques, 187 locations were exposed to laser powers from 50 to 210 mW. Laser exposure locations were monitored for up to 18 months using fluorescein angiography (FA), optical coherence tomography (OCT), scanning laser ophthalmoscopy (SLO), adaptive optics scanning laser ophthalmoscope (AOSLO) reflectance imaging, two-photon excited fluorescence (TPEF) ophthalmoscopy, histology, and calcium responses of retinal ganglion cells. Results This method produced localized photoreceptor loss with minimal axial spread of damage to other retinal layers, verified by in-vivo structural imaging and histologic examination, although in some cases evidence of altered autofluorescence was found in the adjacent retinal pigment epithelium (RPE). Functional assessment using blood flow imaging of the retinal plexus and calcium imaging of the response of ganglion cells above the photoreceptor loss shows that inner retinal circuitry was preserved. Conclusions Although different from a genetic model of retinal degeneration, this model of localized photoreceptor loss may provide a useful testbed for vision restoration studies in nonhuman primates. Translational Relevance With this model, a variety of vision restoration methods can be tested in the non-human primate.
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Affiliation(s)
- Kamal R Dhakal
- Center for Visual Science, University of Rochester, Rochester, NY, USA
| | - Sarah Walters
- Center for Visual Science, University of Rochester, Rochester, NY, USA.,The Institute of Optics, University of Rochester, Rochester, NY, USA
| | | | - Christina Schwarz
- Center for Visual Science, University of Rochester, Rochester, NY, USA.,Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | | | | | - Brittany Bateman
- Flaum Eye Institute, University of Rochester, Rochester, NY, USA
| | - Krystel R Huxlin
- Center for Visual Science, University of Rochester, Rochester, NY, USA.,The Institute of Optics, University of Rochester, Rochester, NY, USA.,Flaum Eye Institute, University of Rochester, Rochester, NY, USA
| | - Jennifer J Hunter
- Center for Visual Science, University of Rochester, Rochester, NY, USA.,The Institute of Optics, University of Rochester, Rochester, NY, USA.,Flaum Eye Institute, University of Rochester, Rochester, NY, USA
| | - David R Williams
- Center for Visual Science, University of Rochester, Rochester, NY, USA.,The Institute of Optics, University of Rochester, Rochester, NY, USA
| | - William H Merigan
- Center for Visual Science, University of Rochester, Rochester, NY, USA.,Flaum Eye Institute, University of Rochester, Rochester, NY, USA
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53
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Simon CJ, Sahel JA, Duebel J, Herlitze S, Dalkara D. Opsins for vision restoration. Biochem Biophys Res Commun 2020; 527:325-330. [DOI: 10.1016/j.bbrc.2019.12.117] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 12/20/2019] [Indexed: 12/17/2022]
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Comparison of AAV-Mediated Optogenetic Vision Restoration between Retinal Ganglion Cell Expression and ON Bipolar Cell Targeting. MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT 2020; 18:15-23. [PMID: 32548211 PMCID: PMC7287188 DOI: 10.1016/j.omtm.2020.05.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 05/19/2020] [Indexed: 01/06/2023]
Abstract
The loss of photoreceptors in individuals with retinal degenerative diseases leads to partial or complete blindness. Optogenetic therapy is a promising approach for restoring vision to the blind. Multiple strategies have been employed by targeting genetically encoded light sensors, particularly channelrhodopsins, to surviving retinal neurons in animal models. In particular, the strategy of targeting retinal bipolar cells has commonly been expected to result in better vision than ubiquitous expression in retinal ganglion cells. However, a direct comparison of the channelrhodopsin-restored vision between these two strategies has not been performed. Here, we compared the restored visual functions achieved by adeno-associated virus (AAV)-mediated expression of a channelrhodopsin in ON-type bipolar cells and retinal ganglion cells driven by an improved mGluR6 promoter and a CAG promoter, respectively, in a blind mouse model by performing electrophysiological recordings and behavioral assessments. Unexpectedly, the efficacy of the restored vision based on light sensitivity and visual acuity was much higher following ubiquitous retinal ganglion cell expression than that of the strategy targeting ON-type bipolar cells. Our study suggests that, at least based on currently available gene delivery techniques, the expression of genetically encoded light sensors in retinal ganglion cells is likely a practical and advantageous strategy for optogenetic vision restoration.
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55
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Gundelach LA, Hüser MA, Beutner D, Ruther P, Bruegmann T. Towards the clinical translation of optogenetic skeletal muscle stimulation. Pflugers Arch 2020; 472:527-545. [PMID: 32415463 PMCID: PMC7239821 DOI: 10.1007/s00424-020-02387-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 03/05/2020] [Accepted: 04/28/2020] [Indexed: 12/27/2022]
Abstract
Paralysis is a frequent phenomenon in many diseases, and to date, only functional electrical stimulation (FES) mediated via the innervating nerve can be employed to restore skeletal muscle function in patients. Despite recent progress, FES has several technical limitations and significant side effects. Optogenetic stimulation has been proposed as an alternative, as it may circumvent some of the disadvantages of FES enabling cell type–specific, spatially and temporally precise stimulation of cells expressing light-gated ion channels, commonly Channelrhodopsin2. Two distinct approaches for the restoration of skeletal muscle function with optogenetics have been demonstrated: indirect optogenetic stimulation through the innervating nerve similar to FES and direct optogenetic stimulation of the skeletal muscle. Although both approaches show great promise, both have their limitations and there are several general hurdles that need to be overcome for their translation into clinics. These include successful gene transfer, sustained optogenetic protein expression, and the creation of optically active implantable devices. Herein, a comprehensive summary of the underlying mechanisms of electrical and optogenetic approaches is provided. With this knowledge in mind, we substantiate a detailed discussion of the advantages and limitations of each method. Furthermore, the obstacles in the way of clinical translation of optogenetic stimulation are discussed, and suggestions on how they could be overcome are provided. Finally, four specific examples of pathologies demanding novel therapeutic measures are discussed with a focus on the likelihood of direct versus indirect optogenetic stimulation.
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Affiliation(s)
- Lili A Gundelach
- Institute of Cardiovascular Physiology, University Medical Center, Göttingen, Germany
| | - Marc A Hüser
- Institute of Cardiovascular Physiology, University Medical Center, Göttingen, Germany
- Department of Otorhinolaryngology, Head and Neck Surgery, University Medical Center, Göttingen, Germany
| | - Dirk Beutner
- Department of Otorhinolaryngology, Head and Neck Surgery, University Medical Center, Göttingen, Germany
| | - Patrick Ruther
- Microsystem Materials Laboratory, Department of Microsystems Engineering (IMTEK), University of Freiburg, Freiburg, Germany
- BrainLinks-BrainTools Cluster of Excellence at the University of Freiburg, Freiburg, Germany
| | - Tobias Bruegmann
- Institute of Cardiovascular Physiology, University Medical Center, Göttingen, Germany.
- DZHK e.V. (German Center for Cardiovascular Research), Partner Site Göttingen, Göttingen, Germany.
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Dieter A, Keppeler D, Moser T. Towards the optical cochlear implant: optogenetic approaches for hearing restoration. EMBO Mol Med 2020; 12:e11618. [PMID: 32227585 PMCID: PMC7136966 DOI: 10.15252/emmm.201911618] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 01/08/2020] [Accepted: 01/28/2020] [Indexed: 12/30/2022] Open
Abstract
Cochlear implants (CIs) are considered the most successful neuroprosthesis as they enable speech comprehension in the majority of half a million CI users suffering from sensorineural hearing loss. By electrically stimulating the auditory nerve, CIs constitute an interface re-connecting the brain and the auditory scene, providing the patient with information regarding the latter. However, since electric current is hard to focus in conductive environments such as the cochlea, the precision of electrical sound encoding-and thus quality of artificial hearing-is limited. Recently, optogenetic stimulation of the cochlea has been suggested as an alternative approach for hearing restoration. Cochlear optogenetics promises increased spectral selectivity of artificial sound encoding, hence improved hearing, as light can conveniently be confined in space to activate the auditory nerve within smaller tonotopic ranges. In this review, we discuss the latest experimental and technological developments of cochlear optogenetics and outline the remaining challenges on the way to clinical translation.
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Affiliation(s)
- Alexander Dieter
- Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
- Göttingen Graduate School for NeurosciencesBiophysics and Molecular BiosciencesUniversity of GöttingenGöttingenGermany
| | - Daniel Keppeler
- Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
| | - Tobias Moser
- Institute for Auditory Neuroscience and InnerEarLabUniversity Medical Center GöttingenGöttingenGermany
- Auditory Neuroscience and Optogenetics LaboratoryGerman Primate CenterGöttingenGermany
- Auditory Neuroscience GroupMax Planck Institute of Experimental MedicineGöttingenGermany
- Cluster of Excellence “Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells” (MBExC)University of GöttingenGöttingenGermany
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57
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Kamar S, Howlett MHC, Klooster J, de Graaff W, Csikós T, Rabelink MJWE, Hoeben RC, Kamermans M. Degenerated Cones in Cultured Human Retinas Can Successfully Be Optogenetically Reactivated. Int J Mol Sci 2020; 21:ijms21020522. [PMID: 31947650 PMCID: PMC7014344 DOI: 10.3390/ijms21020522] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 01/11/2020] [Accepted: 01/13/2020] [Indexed: 12/14/2022] Open
Abstract
Biblical references aside, restoring vision to the blind has proven to be a major technical challenge. In recent years, considerable advances have been made towards this end, especially when retinal degeneration underlies the vision loss such as occurs with retinitis pigmentosa. Under these conditions, optogenetic therapies are a particularly promising line of inquiry where remaining retinal cells are made into "artificial photoreceptors". However, this strategy is not without its challenges and a model system using human retinal explants would aid its continued development and refinement. Here, we cultured post-mortem human retinas and show that explants remain viable for around 7 days. Within this period, the cones lose their outer segments and thus their light sensitivity but remain electrophysiologically intact, displaying all the major ionic conductances one would expect for a vertebrate cone. We optogenetically restored light responses to these quiescent cones using a lentivirus vector constructed to express enhanced halorhodopsin under the control of the human arrestin promotor. In these 'reactivated' retinas, we show a light-induced horizontal cell to cone feedback signal in cones, indicating that transduced cones were able to transmit their light response across the synapse to horizontal cells, which generated a large enough response to send a signal back to the cones. Furthermore, we show ganglion cell light responses, suggesting the cultured explant's condition is still good enough to support transmission of the transduced cone signal over the intermediate retinal layers to the final retinal output level. Together, these results show that cultured human retinas are an appropriate model system to test optogenetic vision restoration approaches and that cones which have lost their outer segment, a condition occurring during the early stages of retinitis pigmentosa, are appropriate targets for optogenetic vision restoration therapies.
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Affiliation(s)
- Sizar Kamar
- Netherlands Institute for Neuroscience, 1105 BA Amsterdam-Zuidoost, The Netherlands; (S.K.); (M.H.C.H.); (J.K.); (W.d.G.); (T.C.)
- Department of Ophthalmology, Leiden University Medical Center, P.O. Box 9600, 2300 RC Leiden, The Netherlands
| | - Marcus H. C. Howlett
- Netherlands Institute for Neuroscience, 1105 BA Amsterdam-Zuidoost, The Netherlands; (S.K.); (M.H.C.H.); (J.K.); (W.d.G.); (T.C.)
| | - Jan Klooster
- Netherlands Institute for Neuroscience, 1105 BA Amsterdam-Zuidoost, The Netherlands; (S.K.); (M.H.C.H.); (J.K.); (W.d.G.); (T.C.)
| | - Wim de Graaff
- Netherlands Institute for Neuroscience, 1105 BA Amsterdam-Zuidoost, The Netherlands; (S.K.); (M.H.C.H.); (J.K.); (W.d.G.); (T.C.)
| | - Tamás Csikós
- Netherlands Institute for Neuroscience, 1105 BA Amsterdam-Zuidoost, The Netherlands; (S.K.); (M.H.C.H.); (J.K.); (W.d.G.); (T.C.)
| | - Martijn J. W. E. Rabelink
- Department of Cell and Chemical Biology, Leiden University Medical Center, P.O. Box 9600, 2300 RC Leiden, The Netherlands; (M.J.W.E.R.); (R.C.H.)
| | - Rob C. Hoeben
- Department of Cell and Chemical Biology, Leiden University Medical Center, P.O. Box 9600, 2300 RC Leiden, The Netherlands; (M.J.W.E.R.); (R.C.H.)
| | - Maarten Kamermans
- Netherlands Institute for Neuroscience, 1105 BA Amsterdam-Zuidoost, The Netherlands; (S.K.); (M.H.C.H.); (J.K.); (W.d.G.); (T.C.)
- Department of Biomedical Engineering & Physics, Amsterdam University Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
- Correspondence:
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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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Abstract
Monkeys are a premier model organism for neuroscience research. Activity in the central nervous systems of monkeys can be recorded and manipulated while they perform complex perceptual, motor, or cognitive tasks. Conventional techniques for manipulating neural activity in monkeys are too coarse to address many of the outstanding questions in primate neuroscience, but optogenetics holds the promise to overcome this hurdle. In this article, we review the progress that has been made in primate optogenetics over the past 5 years. We emphasize the use of gene regulatory sequences in viral vectors to target specific neuronal types, and we present data on vectors that we engineered to target parvalbumin-expressing neurons. We conclude with a discussion of the utility of optogenetics for treating sensorimotor hearing loss and Parkinson's disease, areas of translational neuroscience in which monkeys provide unique leverage for basic science and medicine.
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60
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Montazeri L, El Zarif N, Trenholm S, Sawan M. Optogenetic Stimulation for Restoring Vision to Patients Suffering From Retinal Degenerative Diseases: Current Strategies and Future Directions. IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS 2019; 13:1792-1807. [PMID: 31689206 DOI: 10.1109/tbcas.2019.2951298] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Optogenetic strategies for vision restoration involve photosensitizing surviving retinal neurons following retinal degeneration, using emerging optogenetic techniques. This approach opens the door to a minimally-invasive retinal vision restoration approach. Moreover, light stimulation has the potential to offer better spatial and temporal resolution than conventional retinal electrical prosthetics. Although proof-of-concept studies in animal models have demonstrated the possibility of restoring vision using optogenetic techniques, and initial clinical trials are underway, there are still hurdles to pass before such an approach restores naturalistic vision in humans. One limitation is the development of light stimulation devices to activate optogenetic channels in the retina. Here we review recent progress in the design and implementation of optogenetic stimulation devices and outline the corresponding technological challenges. Finally, while most work to date has focused on providing therapy to patients suffering from retinitis pigmentosa, we provide additional insights into strategies for applying optogenetic vision restoration to patients suffering from age-related macular degeneration.
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Gruber A, Edri O, Gepstein L. Cardiac optogenetics: the next frontier. Europace 2019; 20:1910-1918. [PMID: 29315402 DOI: 10.1093/europace/eux371] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Accepted: 12/14/2017] [Indexed: 12/21/2022] Open
Abstract
The emerging technology of optogenetics uses optical and genetic means to monitor and modulate the electrophysiological properties of excitable tissues. While transforming the field of neuroscience, the technology has recently gained popularity also in the cardiac arena. Here, we describe the basic principles of optogenetics, the available and evolving optogenetic tools, and the unique potential of this technology for basic and translational cardiac electrophysiology. Specifically, we discuss the ability to control (augment or suppress) the cardiac tissue's excitable properties using optogenetic actuators (microbial opsins), which are light-gated ion channels and pumps that can cause light-triggered membrane depolarization or hyperpolarization. We then focus on the potential clinical implications of this technology for the treatment of cardiac arrhythmias by describing recent efforts for developing optogenetic-based cardiac pacing, resynchronization, and defibrillation experimental strategies. Finally, the significant obstacles and challenges that need to be overcome before any future clinical translation can be expected are discussed.
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Affiliation(s)
- Amit Gruber
- The Sohnis Family Reaserch Laboratory for Cardiac Electrophysiology and Regenerative Medicine, Rappaport Faculty of Medicine and Research Institute, Technion- Israel Institute of Technology, Haifa, Israel
| | - Oded Edri
- The Sohnis Family Reaserch Laboratory for Cardiac Electrophysiology and Regenerative Medicine, Rappaport Faculty of Medicine and Research Institute, Technion- Israel Institute of Technology, Haifa, Israel
| | - Lior Gepstein
- The Sohnis Family Reaserch Laboratory for Cardiac Electrophysiology and Regenerative Medicine, Rappaport Faculty of Medicine and Research Institute, Technion- Israel Institute of Technology, Haifa, Israel.,Cardiology Department of Rambam Health Care Campus, HaAliya HaShniya St 8, Haifa, Israel
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Richter C, Bruegmann T. No light without the dark: Perspectives and hindrances for translation of cardiac optogenetics. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2019; 154:39-50. [PMID: 31515056 DOI: 10.1016/j.pbiomolbio.2019.08.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 08/18/2019] [Accepted: 08/27/2019] [Indexed: 12/30/2022]
Abstract
Over the last decade, optogenetic stimulation of the heart and its translational potential for rhythm control attracted more and more interest. Optogenetics allows to stimulate cardiomyocytes expressing the light-gated cation channel Channelrhodopsin 2 (ChR2) with light and thus high spatio-temporal precision. Therefore this new approach can overcome the technical limitations of electrical stimulation. In regard of translational approaches, the prospect of pain-free stimulation, if ChR2 expression is restricted to cardiomyocytes, is especially intriguing and could be highly beneficial for cardioversion and defibrillation. However, there is no light without shadow and cardiac optogenetics has to surmount critical hurdles, namely "how" to inscribe light-sensitivity by expressing ChR2 in a native heart and how to avoid side effects such as possible immune responses against the gene transfer. Furthermore, implantable light devices have to be developed which ensure sufficient illumination in a highly contractile environment. Therefore this article reviews recent advantages in the field of cardiac optogenetics with a special focus on the hindrances for the potential translation of this new approach into clinics and provides an outlook how these have to be carefully investigated and could be solved step by step.
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Affiliation(s)
- Claudia Richter
- RG Biomedical Physics, Max Planck Institute for Dynamics & Self-Organization, Am Fassberg 17, 37077, Goettingen, Germany; Department of Cardiology and Pneumology, University Medical Center, Robert-Koch-Str. 42a, 37075, Goettingen, Germany; DZHK e.V. (German Center for Cardiovascular Research), Partner Site Goettingen, 37075, Goettingen, Germany.
| | - Tobias Bruegmann
- DZHK e.V. (German Center for Cardiovascular Research), Partner Site Goettingen, 37075, Goettingen, Germany; Institute for Cardiovascular Physiology, University Medical Center Goettingen, Humboldtallee 23, 37073, Goettingen, Germany.
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Sardoiwala MN, Srivastava AK, Karmakar S, Roy Choudhury S. Nanostructure Endows Neurotherapeutic Potential in Optogenetics: Current Development and Future Prospects. ACS Chem Neurosci 2019; 10:3375-3385. [PMID: 31244053 DOI: 10.1021/acschemneuro.9b00246] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Optogenetics have evolved as a promising tool to control the processes at a cellular level via photons. Specially, it confers a specific control over cellular function through real-time cytomodulation even in freely moving animals. Neuronal stimulation is prerequisite for deep tissue light penetration or insertion of optrode for light illumination to the neurons that have been proven to be compromised due to poor light penetration and invasiveness of the procedure, respectively. In this review, the application of nanotechnology is being elaborated by the use of metal nanoparticles (AuNPs), upconversion nanocrystals (UCNPs), and quantum dots (CdSe) for targeting particular organs or tissues, and their potential to emit a specific light on excitation to overcome the limitations associated with earlier methods has been elucidated. The optothermal and magnetothermal properties, photoluminescence, and higher photostability of nanomaterials are explored in context of therapeutic applicability of optogenetics. The nanostructure characteristics and specific ion channel targeting have shown promising therapeutic potential against neurodegenerative disorders (Alzheimer's, Parkinson's, Huntington's), epilepsy, and blindness. This review compiles mechanical and optical characteristics of nanomaterials that endow superior optogenetic therapeutic potentials to cure immedicable infirmities.
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Affiliation(s)
| | - Anup K. Srivastava
- Institute of Nano Science and Technology, Habitat Centre, Phase-10, Mohali, Punjab 160062, India
| | - Surajit Karmakar
- Institute of Nano Science and Technology, Habitat Centre, Phase-10, Mohali, Punjab 160062, India
| | - Subhasree Roy Choudhury
- Institute of Nano Science and Technology, Habitat Centre, Phase-10, Mohali, Punjab 160062, India
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Wood EH, Tang PH, De la Huerta I, Korot E, Muscat S, Palanker DA, Williams GA. STEM CELL THERAPIES, GENE-BASED THERAPIES, OPTOGENETICS, AND RETINAL PROSTHETICS: Current State and Implications for the Future. Retina 2019; 39:820-835. [PMID: 30664120 PMCID: PMC6492547 DOI: 10.1097/iae.0000000000002449] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
PURPOSE To review and discuss current innovations and future implications of promising biotechnology and biomedical offerings in the field of retina. We focus on therapies that have already emerged as clinical offerings or are poised to do so. METHODS Literature review and commentary focusing on stem cell therapies, gene-based therapies, optogenetic therapies, and retinal prosthetic devices. RESULTS The technologies discussed herein are some of the more recent promising biotechnology and biomedical developments within the field of retina. Retinal prosthetic devices and gene-based therapies both have an FDA-approved product for ophthalmology, and many other offerings (including optogenetics) are in the pipeline. Stem cell therapies offer personalized medicine through novel regenerative mechanisms but entail complex ethical and reimbursement challenges. CONCLUSION Stem cell therapies, gene-based therapies, optogenetics, and retinal prosthetic devices represent a new era of biotechnological and biomedical progress. These bring new ethical, regulatory, care delivery, and reimbursement challenges. By addressing these issues proactively, we may accelerate delivery of care to patients in a safe, efficient, and value-based manner.
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Affiliation(s)
| | - Peter H Tang
- Department of Ophthalmology, Hansen Experimental Physics Laboratory, Stanford University, Stanford, California
| | | | - Edward Korot
- Oakland University William Beaumont School of Medicine, Rochester, Michigan
| | | | - Daniel A Palanker
- Department of Ophthalmology, Hansen Experimental Physics Laboratory, Stanford University, Stanford, California
| | - George A Williams
- Associated Retinal Consultants, Royal Oak, Michigan
- Oakland University William Beaumont School of Medicine, Rochester, Michigan
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Ganjawala TH, Lu Q, Fenner MD, Abrams GW, Pan ZH. Improved CoChR Variants Restore Visual Acuity and Contrast Sensitivity in a Mouse Model of Blindness under Ambient Light Conditions. Mol Ther 2019; 27:1195-1205. [PMID: 31010741 DOI: 10.1016/j.ymthe.2019.04.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Revised: 04/03/2019] [Accepted: 04/03/2019] [Indexed: 11/15/2022] Open
Abstract
Severe photoreceptor cell death in retinal degenerative diseases leads to partial or complete blindness. Optogenetics is a promising strategy to treat blindness. The feasibility of this strategy has been demonstrated through the ectopic expression of microbial channelrhodopsins (ChRs) and other genetically encoded light sensors in surviving retinal neurons in animal models. A major drawback for ChR-based visual restoration is low light sensitivity. Here, we report the development of highly operational light-sensitive ChRs by optimizing the kinetics of a recently reported ChR variant, Chloromonas oogama (CoChR). In particular, we identified two CoChR mutants, CoChR-L112C and CoChR-H94E/L112C/K264T, with markedly enhanced light sensitivity. The improved light sensitivity of the CoChR mutants was confirmed by ex vivo electrophysiological recordings in the retina. Furthermore, the CoChR mutants restored the vision of a blind mouse model under ambient light conditions with remarkably good contrast sensitivity and visual acuity, as evidenced by the results of behavioral assays. The ability to restore functional vision under normal light conditions with the improved CoChR variants removed a major obstacle for ChR-based optogenetic vision restoration.
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Affiliation(s)
- Tushar H Ganjawala
- Department of Ophthalmology, Visual and Anatomical Sciences, Kresge Eye Institute, Wayne State University School of Medicine, Detroit, MI, USA
| | - Qi Lu
- Department of Ophthalmology, Visual and Anatomical Sciences, Kresge Eye Institute, Wayne State University School of Medicine, Detroit, MI, USA
| | - Mitchell D Fenner
- Department of Ophthalmology, Visual and Anatomical Sciences, Kresge Eye Institute, Wayne State University School of Medicine, Detroit, MI, USA
| | - Gary W Abrams
- Department of Ophthalmology, Visual and Anatomical Sciences, Kresge Eye Institute, Wayne State University School of Medicine, Detroit, MI, USA
| | - Zhuo-Hua Pan
- Department of Ophthalmology, Visual and Anatomical Sciences, Kresge Eye Institute, Wayne State University School of Medicine, Detroit, MI, USA.
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Berry MH, Holt A, Salari A, Veit J, Visel M, Levitz J, Aghi K, Gaub BM, Sivyer B, Flannery JG, Isacoff EY. Restoration of high-sensitivity and adapting vision with a cone opsin. Nat Commun 2019; 10:1221. [PMID: 30874546 PMCID: PMC6420663 DOI: 10.1038/s41467-019-09124-x] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Accepted: 02/20/2019] [Indexed: 01/27/2023] Open
Abstract
Inherited and age-related retinal degenerative diseases cause progressive loss of rod and cone photoreceptors, leading to blindness, but spare downstream retinal neurons, which can be targeted for optogenetic therapy. However, optogenetic approaches have been limited by either low light sensitivity or slow kinetics, and lack adaptation to changes in ambient light, and not been shown to restore object vision. We find that the vertebrate medium wavelength cone opsin (MW-opsin) overcomes these limitations and supports vision in dim light. MW-opsin enables an otherwise blind retinitis pigmenotosa mouse to discriminate temporal and spatial light patterns displayed on a standard LCD computer tablet, displays adaption to changes in ambient light, and restores open-field novel object exploration under incidental room light. By contrast, rhodopsin, which is similar in sensitivity but slower in light response and has greater rundown, fails these tests. Thus, MW-opsin provides the speed, sensitivity and adaptation needed to restore patterned vision.
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Affiliation(s)
- Michael H Berry
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, 94720, USA
- Department of Physiology and Pharmacology, Oregon Health and Sciences University, Portland, OR, 97239, USA
| | - Amy Holt
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, 94720, USA
| | - Autoosa Salari
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, 94720, USA
| | - Julia Veit
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, 94720, USA
- Helen Wills Neuroscience Institute, University of California, Berkeley, CA, 94720, USA
| | - Meike Visel
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, 94720, USA
| | - Joshua Levitz
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, 94720, USA
- Department of Biochemistry, Weill Cornell Medicine, New York, NY, 10024, USA
| | - Krisha Aghi
- Helen Wills Neuroscience Institute, University of California, Berkeley, CA, 94720, USA
| | - Benjamin M Gaub
- Helen Wills Neuroscience Institute, University of California, Berkeley, CA, 94720, USA
- Department of Biosystems Science Engineering, ETH Zürich, Mattenstrasse 26, Basel, 8092, Switzerland
| | - Benjamin Sivyer
- Department of Physiology and Pharmacology, Oregon Health and Sciences University, Portland, OR, 97239, USA
- Department of Ophthalmology, Casey Eye Institute, Oregon Health and Science University, Portland, OR, 97239, USA
| | - John G Flannery
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, 94720, USA
- Helen Wills Neuroscience Institute, University of California, Berkeley, CA, 94720, USA
- School of Optometry, University of California, Berkeley, CA, 94720, USA
| | - Ehud Y Isacoff
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, 94720, USA.
- Helen Wills Neuroscience Institute, University of California, Berkeley, CA, 94720, USA.
- Bioscience Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
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67
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A light in the dark: state of the art and perspectives in optogenetics and optopharmacology for restoring vision. Future Med Chem 2019; 11:463-487. [DOI: 10.4155/fmc-2018-0315] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
In the last decade, innovative therapeutic strategies against inherited retinal degenerations (IRDs) have emerged. In particular, chemical- and opto-genetics approaches or a combination of them have been identified for modulating neuronal/optical activity in order to restore vision in blinding diseases. The ‘chemical-genetics approach’ (optopharmacology) uses small molecules (exogenous photoswitches) for restoring light sensitivity by activating ion channels. The ‘opto-genetics approach’ employs light-activated photosensitive proteins (exogenous opsins), introduced by viral vectors in injured tissues, to restore light response. These approaches offer control of neuronal activities with spatial precision and limited invasiveness, although with some drawbacks. Currently, a combined therapeutic strategy (optogenetic pharmacology) is emerging. This review describes the state of the art and provides an overview of the future perspectives in vision restoration.
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Liu W, Liu M, Liu Y, Li S, Weng C, Fu Y, He J, Gong Y, Liu W, Zhao C, Yin ZQ. Validation and Safety of Visual Restoration by Ectopic Expression of Human Melanopsin in Retinal Ganglion Cells. Hum Gene Ther 2019; 30:714-726. [PMID: 30582371 DOI: 10.1089/hum.2018.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
To study whether ectopic human melanopsin (hMel) in retinal ganglion cells (RGCs) could restore the visual function in end-stage retinal degeneration, AAV2/8-CMV-hMel/FYP was injected into the intravitreal space of Royal College of Surgeons (RCS) rats. It was observed that ectopic hMel/yellow fluorescent protein (YFP) was dominantly expressed in the RGCs of the RCS rat retinae. At 30-45 days after administration of AAV2/8-CMV-hMel/FYP in RCS rats, the flash visual evoked potentials and behavioral results demonstrated that visual function was significantly improved compared to that in the control group, while no improvement in flash electroretinography was observed at this time point. To translate this potential therapeutic approach to the clinic, the safety of viral vectors in the retinae of normal macaques was then studied, and the expression profile of exogenous hMel with/without internal limiting membrane peeling was compared before viral vector administration. The data revealed that there was no significant difference in the number of RGCs containing exogenous hMel/YFP between the two groups. Whole-cell patch-clamp recordings demonstrated that the hMel/YFP-positive RGCs of the macaque retinae reacted to the intense light stimulation, generating inward currents and action potentials. This result confirms that the ectopic hMel expressed in RGCs is functional. Moreover, the introduction of AAV2/8-CMV-hMel/FYP does not cause detectable pathological effects. Thus, this study suggests that AAV2/8-CMV-hMel/FYP administration without internal limiting membrane peeling is safe and feasible for efficient transduction and provides therapeutic benefits to restore the visual function of patients suffering photoreceptor loss.
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Affiliation(s)
- Wenyi Liu
- 1 Southwest Hospital/Southwest Eye Hospital, Third Military Medical University, Chongqing, P.R. China; and Chongqing, P.R. China.,2 Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, P.R. China
| | - Mingming Liu
- 1 Southwest Hospital/Southwest Eye Hospital, Third Military Medical University, Chongqing, P.R. China; and Chongqing, P.R. China.,2 Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, P.R. China
| | - Yong Liu
- 1 Southwest Hospital/Southwest Eye Hospital, Third Military Medical University, Chongqing, P.R. China; and Chongqing, P.R. China.,2 Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, P.R. China
| | - ShiYing Li
- 1 Southwest Hospital/Southwest Eye Hospital, Third Military Medical University, Chongqing, P.R. China; and Chongqing, P.R. China.,2 Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, P.R. China
| | - Chuanhuang Weng
- 1 Southwest Hospital/Southwest Eye Hospital, Third Military Medical University, Chongqing, P.R. China; and Chongqing, P.R. China.,2 Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, P.R. China
| | - Yan Fu
- 1 Southwest Hospital/Southwest Eye Hospital, Third Military Medical University, Chongqing, P.R. China; and Chongqing, P.R. China.,2 Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, P.R. China
| | - Juncai He
- 1 Southwest Hospital/Southwest Eye Hospital, Third Military Medical University, Chongqing, P.R. China; and Chongqing, P.R. China.,2 Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, P.R. China
| | - Yu Gong
- 1 Southwest Hospital/Southwest Eye Hospital, Third Military Medical University, Chongqing, P.R. China; and Chongqing, P.R. China.,2 Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, P.R. China
| | - Weiping Liu
- 1 Southwest Hospital/Southwest Eye Hospital, Third Military Medical University, Chongqing, P.R. China; and Chongqing, P.R. China.,2 Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, P.R. China
| | - CongJian Zhao
- 1 Southwest Hospital/Southwest Eye Hospital, Third Military Medical University, Chongqing, P.R. China; and Chongqing, P.R. China.,2 Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, P.R. China
| | - Zheng Qin Yin
- 1 Southwest Hospital/Southwest Eye Hospital, Third Military Medical University, Chongqing, P.R. China; and Chongqing, P.R. China.,2 Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, P.R. China
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Vision Restoration in Outer Retinal Degenerations: Current Approaches and Future Directions. Int Ophthalmol Clin 2018; 59:59-69. [PMID: 30585918 DOI: 10.1097/iio.0000000000000257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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70
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Rodrigues GA, Shalaev E, Karami TK, Cunningham J, Slater NKH, Rivers HM. Pharmaceutical Development of AAV-Based Gene Therapy Products for the Eye. Pharm Res 2018; 36:29. [PMID: 30591984 PMCID: PMC6308217 DOI: 10.1007/s11095-018-2554-7] [Citation(s) in RCA: 134] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 11/30/2018] [Indexed: 12/18/2022]
Abstract
A resurgence of interest and investment in the field of gene therapy, driven in large part by advances in viral vector technology, has recently culminated in United States Food and Drug Administration approval of the first gene therapy product targeting a disease caused by mutations in a single gene. This product, LUXTURNA™ (voretigene neparvovec-rzyl; Spark Therapeutics, Inc., Philadelphia, PA), delivers a normal copy of the RPE65 gene to retinal cells for the treatment of biallelic RPE65 mutation–associated retinal dystrophy, a blinding disease. Many additional gene therapy programs targeting both inherited retinal diseases and other ocular diseases are in development, owing to an improved understanding of the genetic basis of ocular disease and the unique properties of the ocular compartment that make it amenable to local gene therapy. Here we review the growing body of literature that describes both the design and development of ocular gene therapy products, with a particular emphasis on target and vector selection, and chemistry, manufacturing, and controls.
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Affiliation(s)
| | - Evgenyi Shalaev
- Pharmaceutical Research and Development, Allergan plc, 2525 Dupont Drive, Irvine, California, 92612-1531, USA
| | - Thomas K Karami
- Pharmaceutical Research and Development, Allergan plc, 2525 Dupont Drive, Irvine, California, 92612-1531, USA
| | - James Cunningham
- Pharmaceutical Research and Development, Allergan plc, 2525 Dupont Drive, Irvine, California, 92612-1531, USA
| | - Nigel K H Slater
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, CB3 0AS, UK
| | - Hongwen M Rivers
- Pharmaceutical Research and Development, Allergan plc, 2525 Dupont Drive, Irvine, California, 92612-1531, USA.
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71
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Garita-Hernandez M, Guibbal L, Toualbi L, Routet F, Chaffiol A, Winckler C, Harinquet M, Robert C, Fouquet S, Bellow S, Sahel JA, Goureau O, Duebel J, Dalkara D. Optogenetic Light Sensors in Human Retinal Organoids. Front Neurosci 2018; 12:789. [PMID: 30450028 PMCID: PMC6224345 DOI: 10.3389/fnins.2018.00789] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 10/12/2018] [Indexed: 01/26/2023] Open
Abstract
Optogenetic technologies paved the way to dissect complex neural circuits and monitor neural activity using light in animals. In retinal disease, optogenetics has been used as a therapeutic modality to reanimate the retina after the loss of photoreceptor outer segments. However, it is not clear today which ones of the great diversity of microbial opsins are best suited for therapeutic applications in human retinas as cell lines, primary cell cultures and animal models do not predict expression patterns of microbial opsins in human retinal cells. Therefore, we sought to generate retinal organoids derived from human induced pluripotent stem cells (hiPSCs) as a screening tool to explore the membrane trafficking efficacy of some recently described microbial opsins. We tested both depolarizing and hyperpolarizing microbial opsins including CatCh, ChrimsonR, ReaChR, eNpHR 3.0, and Jaws. The membrane localization of eNpHR 3.0, ReaChR, and Jaws was the highest, likely due to their additional endoplasmic reticulum (ER) release and membrane trafficking signals. In the case of opsins that were not engineered to improve trafficking efficiency in mammalian cells such as CatCh and ChrimsonR, membrane localization was less efficient. Protein accumulation in organelles such as ER and Golgi was observed at high doses with CatCh and ER retention lead to an unfolded protein response. Also, cytoplasmic localization was observed at high doses of ChrimsonR. Our results collectively suggest that retinal organoids derived from hiPSCs can be used to predict the subcellular fate of optogenetic proteins in a human retinal context. Such organoids are also versatile tools to validate other gene therapy products and drug molecules.
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Affiliation(s)
| | - Laure Guibbal
- Institut de la Vision, Sorbonne Université, INSERM, CNRS, Paris, France
| | - Lyes Toualbi
- Institut de la Vision, Sorbonne Université, INSERM, CNRS, Paris, France
| | - Fiona Routet
- Institut de la Vision, Sorbonne Université, INSERM, CNRS, Paris, France
| | - Antoine Chaffiol
- Institut de la Vision, Sorbonne Université, INSERM, CNRS, Paris, France
| | - Celine Winckler
- Institut de la Vision, Sorbonne Université, INSERM, CNRS, Paris, France
| | - Marylin Harinquet
- Institut de la Vision, Sorbonne Université, INSERM, CNRS, Paris, France
| | - Camille Robert
- Institut de la Vision, Sorbonne Université, INSERM, CNRS, Paris, France
| | - Stephane Fouquet
- Institut de la Vision, Sorbonne Université, INSERM, CNRS, Paris, France
| | | | - José-Alain Sahel
- Institut de la Vision, Sorbonne Université, INSERM, CNRS, Paris, France
- CHNO des Quinze-Vingts, DHU Sight Restore, INSERM-DGOS CIC 1423, Paris, France
- Department of Ophthalmology, The University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Olivier Goureau
- Institut de la Vision, Sorbonne Université, INSERM, CNRS, Paris, France
| | - Jens Duebel
- Institut de la Vision, Sorbonne Université, INSERM, CNRS, Paris, France
| | - Deniz Dalkara
- Institut de la Vision, Sorbonne Université, INSERM, CNRS, Paris, France
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Baker CK, Flannery JG. Innovative Optogenetic Strategies for Vision Restoration. Front Cell Neurosci 2018; 12:316. [PMID: 30297985 PMCID: PMC6160748 DOI: 10.3389/fncel.2018.00316] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 08/30/2018] [Indexed: 12/27/2022] Open
Abstract
The advent of optogenetics has ushered in a new era in neuroscience where spatiotemporal control of neurons is possible through light application. These tools used to study neural circuits can also be used therapeutically to restore vision. In order to recapitulate the broad spectral and light sensitivities along with high temporal sensitivity found in human vision, researchers have identified and developed new optogenetic tools. There are two major kinds of optogenetic effectors employed in vision restoration: ion channels and G-protein coupled receptors (GPCRs). Ion channel based optogenetic therapies require high intensity light that can be unsafe at lower wavelengths, so work has been done to expand and red-shift the excitation spectra of these channels. Light activatable GPCRs are much more sensitive to light than their ion channel counterparts but are slower kinetically in terms of both activation and inactivation. This review article examines the latest optogenetic ion channel and GPCR candidates for vision restoration based on light and temporal sensitivity.
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Affiliation(s)
- Cameron K. Baker
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, United States
| | - John G. Flannery
- School of Optometry, University of California, Berkeley, Berkeley, CA, United States
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73
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Maimon BE, Diaz M, Revol ECM, Schneider AM, Leaker B, Varela CE, Srinivasan S, Weber MB, Herr HM. Optogenetic Peripheral Nerve Immunogenicity. Sci Rep 2018; 8:14076. [PMID: 30232391 PMCID: PMC6145901 DOI: 10.1038/s41598-018-32075-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 08/28/2018] [Indexed: 12/20/2022] Open
Abstract
Optogenetic technologies have been the subject of great excitement within the scientific community for their ability to demystify complex neurophysiological pathways in the central (CNS) and peripheral nervous systems (PNS). The excitement surrounding optogenetics has also extended to the clinic with a trial for ChR2 in the treatment of retinitis pigmentosa currently underway and additional trials anticipated for the near future. In this work, we identify the cause of loss-of-expression in response to transdermal illumination of an optogenetically active peroneal nerve following an anterior compartment (AC) injection of AAV6-hSyn-ChR2(H134R) with and without a fluorescent reporter. Using Sprague Dawley Rag2-/- rats and appropriate controls, we discover optogenetic loss-of-expression is chiefly elicited by ChR2-mediated immunogenicity in the spinal cord, resulting in both CNS motor neuron death and ipsilateral muscle atrophy in both low and high Adeno-Associated Virus (AAV) dosages. We further employ pharmacological immunosuppression using a slow-release tacrolimus pellet to demonstrate sustained transdermal optogenetic expression up to 12 weeks. These results suggest that all dosages of AAV-mediated optogenetic expression within the PNS may be unsafe. Clinical optogenetics for both PNS and CNS applications should take extreme caution when employing opsins to treat disease and may require concurrent immunosuppression. Future work in optogenetics should focus on designing opsins with lesser immunogenicity.
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Affiliation(s)
- Benjamin E Maimon
- MIT Media Lab, Center for Extreme Bionics, Massachusetts Institute of Technology, Cambridge, MA, USA
- Harvard-MIT Division of Health Sciences and Technology (HST), Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Maurizio Diaz
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Emilie C M Revol
- Department of Bioengineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Alexis M Schneider
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Ben Leaker
- Harvard-MIT Division of Health Sciences and Technology (HST), Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Claudia E Varela
- Harvard-MIT Division of Health Sciences and Technology (HST), Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Shriya Srinivasan
- MIT Media Lab, Center for Extreme Bionics, Massachusetts Institute of Technology, Cambridge, MA, USA
- Harvard-MIT Division of Health Sciences and Technology (HST), Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Matthew B Weber
- MIT Media Lab, Center for Extreme Bionics, Massachusetts Institute of Technology, Cambridge, MA, USA
- Harvard-MIT Division of Health Sciences and Technology (HST), Harvard Medical School, Boston, MA, USA
| | - Hugh M Herr
- MIT Media Lab, Center for Extreme Bionics, Massachusetts Institute of Technology, Cambridge, MA, USA.
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Simunovic MP, Shen W, Lin JY, Protti DA, Lisowski L, Gillies MC. Optogenetic approaches to vision restoration. Exp Eye Res 2018; 178:15-26. [PMID: 30218651 DOI: 10.1016/j.exer.2018.09.003] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 08/16/2018] [Accepted: 09/07/2018] [Indexed: 10/28/2022]
Abstract
Inherited retinal disease (IRD) affects about 1 in 3000 to 1 in 5000 individuals and is now believed to be the most common cause of blindness registration in developed countries. Until recently, the management of such conditions had been exclusively supportive. However, advances in molecular biology and medical engineering have now seen the rise of a variety of approaches to restore vision in patients with IRDs. Optogenetic approaches are primarily aimed at rendering secondary and tertiary neurons of the retina light-sensitive in order to replace degenerate or dysfunctional photoreceptors. Such approaches are attractive because they provide a "causative gene-independent" strategy, which may prove suitable for a variety of patients with IRD. We discuss theoretical and practical considerations in the selection of optogenetic molecules, vectors, surgical approaches and review previous trials of optogenetics for vision restoration. Optogenetic approaches to vision restoration have yielded promising results in pre-clinical trials and a phase I/II clinical trial is currently underway (ClinicalTrials.gov NCT02556736). Despite the significant inroads made in recent years, the ideal optogenetic molecule, vector and surgical approach have yet to be established.
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Affiliation(s)
- M P Simunovic
- Save Sight Institute, University of Sydney, 8 Macquarie St., Sydney, NSW, 2000, Australia; Retinal Unit, Sydney Eye Hospital, 8 Macquarie St., Sydney, NSW, 2000, Australia.
| | - W Shen
- Retinal Unit, Sydney Eye Hospital, 8 Macquarie St., Sydney, NSW, 2000, Australia
| | - J Y Lin
- Faculty of Health, University of Tasmania, Private Bag 23, Hobart, TAS, 7000, Australia
| | - D A Protti
- Discipline of Physiology, University of Sydney, NSW, 2006, Australia
| | - L Lisowski
- Children's Medical Research Institute, University of Sydney, NSW, 2006, Australia; Military Institute of Hygiene and Epidemiology, 24-100, Puławy, Poland
| | - M C Gillies
- Save Sight Institute, University of Sydney, 8 Macquarie St., Sydney, NSW, 2000, Australia; Retinal Unit, Sydney Eye Hospital, 8 Macquarie St., Sydney, NSW, 2000, Australia
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75
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Lu Q, Ganjawala TH, Hattar S, Abrams GW, Pan ZH. A Robust Optomotor Assay for Assessing the Efficacy of Optogenetic Tools for Vision Restoration. Invest Ophthalmol Vis Sci 2018; 59:1288-1294. [PMID: 29625451 PMCID: PMC5839255 DOI: 10.1167/iovs.17-23278] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Purpose To develop an animal behavioral assay for the quantitative assessment of the functional efficacy of optogenetic therapies. Methods A triple-knockout (TKO) mouse line, Gnat1−/−Cnga3−/−Opn4−/−, and a double-knockout mouse line, Gnat1−/−Cnga3−/−, were employed. The expression of channelrhodopsin-2 (ChR2) and its three more light-sensitive mutants, ChR2-L132C, ChR2-L132C/T159C, and ChR2-132C/T159S, in inner retinal neurons was achieved using rAAV2 vectors via intravitreal delivery. Pupillary constriction was assessed by measuring the pupil diameter. The optomotor response (OMR) was examined using a homemade optomotor system equipped with light-emitting diodes as light stimulation. Results A robust OMR was restored in the ChR2-mutant-expressing TKO mice; however, significant pupillary constriction was observed only for the ChR2-L132C/T159S mutant. The ability to evoke an OMR was dependent on both the light intensity and grating frequency. The most light-sensitive frequency for the three ChR2 mutants was approximately 0.042 cycles per degree. Among the three ChR2 mutants, ChR2-L132C/T159S was the most light sensitive, followed by ChR2-L132C/T159C and ChR2-L132C. Melanopsin-mediated pupillary constriction resulted in a substantial reduction in the light sensitivity of the ChR2-mediated OMR. Conclusions The OMR assay using TKO mice enabled the quantitative assessment of the efficacy of different optogenetic tools and the properties of optogenetically restored vision. Thus, the assay can serve as a valuable tool for developing effective optogenetic therapies.
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Affiliation(s)
- Qi Lu
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, Michigan, United States.,Department of Ophthalmology, Kresge Eye Institute, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Tushar H Ganjawala
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Samer Hattar
- National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland, United States
| | - Gary W Abrams
- Department of Ophthalmology, Kresge Eye Institute, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Zhuo-Hua Pan
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, Michigan, United States.,Department of Ophthalmology, Kresge Eye Institute, Wayne State University School of Medicine, Detroit, Michigan, United States
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Goncalves SB, Ribeiro JF, Silva AF, Costa RM, Correia JH. Design and manufacturing challenges of optogenetic neural interfaces: a review. J Neural Eng 2018; 14:041001. [PMID: 28452331 DOI: 10.1088/1741-2552/aa7004] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Optogenetics is a relatively new technology to achieve cell-type specific neuromodulation with millisecond-scale temporal precision. Optogenetic tools are being developed to address neuroscience challenges, and to improve the knowledge about brain networks, with the ultimate aim of catalyzing new treatments for brain disorders and diseases. To reach this ambitious goal the implementation of mature and reliable engineered tools is required. The success of optogenetics relies on optical tools that can deliver light into the neural tissue. Objective/Approach: Here, the design and manufacturing approaches available to the scientific community are reviewed, and current challenges to accomplish appropriate scalable, multimodal and wireless optical devices are discussed. SIGNIFICANCE Overall, this review aims at presenting a helpful guidance to the engineering and design of optical microsystems for optogenetic applications.
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Affiliation(s)
- S B Goncalves
- CMEMS-UMinho, Department of Industrial Electronics, University of Minho, Guimaraes, Portugal
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77
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Yazdan-Shahmorad A, Silversmith DB, Kharazia V, Sabes PN. Targeted cortical reorganization using optogenetics in non-human primates. eLife 2018; 7:31034. [PMID: 29809133 PMCID: PMC5986269 DOI: 10.7554/elife.31034] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2017] [Accepted: 05/05/2018] [Indexed: 12/20/2022] Open
Abstract
Brain stimulation modulates the excitability of neural circuits and drives neuroplasticity. While the local effects of stimulation have been an active area of investigation, the effects on large-scale networks remain largely unexplored. We studied stimulation-induced changes in network dynamics in two macaques. A large-scale optogenetic interface enabled simultaneous stimulation of excitatory neurons and electrocorticographic recording across primary somatosensory (S1) and motor (M1) cortex (Yazdan-Shahmorad et al., 2016). We tracked two measures of network connectivity, the network response to focal stimulation and the baseline coherence between pairs of electrodes; these were strongly correlated before stimulation. Within minutes, stimulation in S1 or M1 significantly strengthened the gross functional connectivity between these areas. At a finer scale, stimulation led to heterogeneous connectivity changes across the network. These changes reflected the correlations introduced by stimulation-evoked activity, consistent with Hebbian plasticity models. This work extends Hebbian plasticity models to large-scale circuits, with significant implications for stimulation-based neurorehabilitation. From riding a bike to reaching for a cup of coffee, all skilled actions rely on precise connections between the sensory and motor areas of the brain. While sensory areas receive and analyse input from the senses, motor areas plan and trigger muscle contractions. Precisely adjusting the connections between these and other areas enables us to learn new skills, and it also helps us to relearn skills lost as a result of brain injury or stroke. About 70 years ago, a psychologist named Donald Hebb came up with an idea for how this process might occur. He proposed that whenever two neurons are active at the same time, the connection between them becomes stronger. This idea, that ‘cells that fire together, wire together’, became known as Hebb’s rule. Many studies have since shown that Hebb’s rule can explain changes in the strength of connections between pairs of neurons. But can it also explain how connections between entire brain regions become stronger or weaker? New results show that it can. The data were obtained using a technique called optogenetics, in which viruses are used to introduce genes for light-sensitive proteins into neurons. Shining light onto the brain will then activate any cells within that area that contain the resulting proteins. Yazdan-Shahmorad, Silversmith et al. used this technique to activate small regions of either sensory or motor brain tissue in live macaque monkeys. Doing so strengthened the overall connectivity between the two areas. The effects were more variable at the level of smaller brain regions, with some connections becoming weaker rather than stronger. However, Yazdan-Shahmorad, Silversmith et al. show that Hebb’s rule explains most of the observed changes. Many neurological and psychiatric disorders stem from abnormal brain connectivity. Simple forms of brain stimulation are already used to treat certain neurological disorders, such as Parkinson’s disease. Stimulating the brain to induce specific changes in connectivity may ultimately enable us to leverage the brain’s natural learning mechanisms to cure, instead of just treat, these conditions.
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Affiliation(s)
- Azadeh Yazdan-Shahmorad
- Department of Physiology, University of California, San Francisco, San Francisco, United States.,Center for Integrative Neuroscience, University of California, San Francisco, San Francisco, United States.,Departments of Bioengineering and Electrical Engineering, University of Washington, Seattle, United States
| | - Daniel B Silversmith
- Center for Integrative Neuroscience, University of California, San Francisco, San Francisco, United States.,UC Berkeley - UCSF Graduate Program in Bioengineering, University of California, San Francisco, San Francisco, United States
| | - Viktor Kharazia
- Center for Integrative Neuroscience, University of California, San Francisco, San Francisco, United States
| | - Philip N Sabes
- Department of Physiology, University of California, San Francisco, San Francisco, United States.,Center for Integrative Neuroscience, University of California, San Francisco, San Francisco, United States.,UC Berkeley - UCSF Graduate Program in Bioengineering, University of California, San Francisco, San Francisco, United States
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78
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Nguyen HX, Kirkton RD, Bursac N. Generation and customization of biosynthetic excitable tissues for electrophysiological studies and cell-based therapies. Nat Protoc 2018; 13:927-945. [PMID: 29622805 PMCID: PMC6050172 DOI: 10.1038/nprot.2018.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
We describe a two-stage protocol to generate electrically excitable and actively conducting cell networks with stable and customizable electrophysiological phenotypes. Using this method, we have engineered monoclonally derived excitable tissues as a robust and reproducible platform to investigate how specific ion channels and mutations affect action potential (AP) shape and conduction. In the first stage of the protocol, we combine computational modeling, site-directed mutagenesis, and electrophysiological techniques to derive optimal sets of mammalian and/or prokaryotic ion channels that produce specific AP shape and conduction characteristics. In the second stage of the protocol, selected ion channels are stably expressed in unexcitable human cells by means of viral or nonviral delivery, followed by flow cytometry or antibiotic selection to purify the desired phenotype. This protocol can be used with traditional heterologous expression systems or primary excitable cells, and application of this method to primary fibroblasts may enable an alternative approach to cardiac cell therapy. Compared with existing methods, this protocol generates a well-defined, relatively homogeneous electrophysiological phenotype of excitable cells that facilitates experimental and computational studies of AP conduction and can decrease arrhythmogenic risk upon cell transplantation. Although basic cell culture and molecular biology techniques are sufficient to generate excitable tissues using the described protocol, experience with patch-clamp techniques is required to characterize and optimize derived cell populations.
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Affiliation(s)
- Hung X Nguyen
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, USA. Correspondence should be addressed to N.B. ()
| | - Robert D Kirkton
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, USA. Correspondence should be addressed to N.B. ()
| | - Nenad Bursac
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, USA. Correspondence should be addressed to N.B. ()
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79
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Gaub BM, Berry MH, Visel M, Holt A, Isacoff EY, Flannery JG. Optogenetic Retinal Gene Therapy with the Light Gated GPCR Vertebrate Rhodopsin. Methods Mol Biol 2018; 1715:177-189. [PMID: 29188513 DOI: 10.1007/978-1-4939-7522-8_12] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
In retinal disease, despite the loss of light sensitivity as photoreceptors die, many retinal interneurons survive in a physiologically and metabolically functional state for long periods. This provides an opportunity for treatment by genetically adding a light sensitive function to these cells. Optogenetic therapies are in development, but, to date, they have suffered from low light sensitivity and narrow dynamic response range of microbial opsins. Expression of light-sensitive G protein coupled receptors (GPCRs), such as vertebrate rhodopsin , can increase sensitivity by signal amplification , as shown by several groups. Here, we describe the methods to (1) express light gated GPCRs in retinal neurons, (2) record light responses in retinal explants in vitro, (3) record cortical light responses in vivo, and (4) test visually guided behavior in treated mice.
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Affiliation(s)
- Benjamin M Gaub
- Department of Biosystems Science and Engineering (D-BSSE), Eidgenössische Technische Hochschule (ETH) Zürich, Basel, Switzerland
| | - Michael H Berry
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, USA
| | - Meike Visel
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, USA
| | - Amy Holt
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, USA
| | - Ehud Y Isacoff
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, USA.,Physical Bioscience Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.,Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA, USA
| | - John G Flannery
- Vision Science Graduate Group, School of Optometry, University of California, Berkeley, CA, USA. .,The Helen Wills Neuroscience Institute, University of California, Berkeley, CA, USA. .,Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA.
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80
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Efficacy and Safety of Glycosidic Enzymes for Improved Gene Delivery to the Retina following Intravitreal Injection in Mice. MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT 2017; 9:192-202. [PMID: 29766027 PMCID: PMC5948313 DOI: 10.1016/j.omtm.2017.12.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/05/2017] [Accepted: 12/19/2017] [Indexed: 11/21/2022]
Abstract
Viral gene delivery is showing great promise for treating retinal disease. Although subretinal vector delivery has mainly been used to date, intravitreal delivery has potential advantages if low retinal transduction efficiency can be overcome. To this end, we investigated the effects of co-injection of glycosaminoglycan-degrading enzymes, singly or in combination, with AAV2 as a method of increasing retinal transduction. Experiments using healthy mice demonstrated that these enzymes enhance retinal transduction. We found that heparinase III produced the greatest individual effect, and this was enhanced further by combination with hyaluronan lyase. In addition, this optimized AAV2-enzyme combination led to a marked improvement in transduction in retinas with advanced retinal degeneration compared with AAV2 alone. Safety studies measuring retinal function by flash electroretinography indicated that retinal function was unaffected in the acute period and at least 12 months after enzyme treatment, whereas pupillometry confirmed that retinal ganglion cell activity was unaffected. Retinal morphology was not altered by the enzyme injection. Collectively these data confirm the efficacy and safety of this intravitreal approach in enhancing retinal transduction efficiency by AAV in rodents. Translating this method into other species, such as non-human primates, or for clinical applications will have challenges and require further studies.
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81
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Restoration of patterned vision with an engineered photoactivatable G protein-coupled receptor. Nat Commun 2017; 8:1862. [PMID: 29192252 PMCID: PMC5709376 DOI: 10.1038/s41467-017-01990-7] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 10/27/2017] [Indexed: 12/21/2022] Open
Abstract
Retinitis pigmentosa results in blindness due to degeneration of photoreceptors, but spares other retinal cells, leading to the hope that expression of light-activated signaling proteins in the surviving cells could restore vision. We used a retinal G protein-coupled receptor, mGluR2, which we chemically engineered to respond to light. In retinal ganglion cells (RGCs) of blind rd1 mice, photoswitch-charged mGluR2 (“SNAG-mGluR2”) evoked robust OFF responses to light, but not in wild-type retinas, revealing selectivity for RGCs that have lost photoreceptor input. SNAG-mGluR2 enabled animals to discriminate parallel from perpendicular lines and parallel lines at varying spacing. Simultaneous viral delivery of the inhibitory SNAG-mGluR2 and excitatory light-activated ionotropic glutamate receptor LiGluR yielded a distribution of expression ratios, restoration of ON, OFF and ON-OFF light responses and improved visual acuity. Thus, SNAG-mGluR2 restores patterned vision and combinatorial light response diversity provides a new logic for enhanced-acuity retinal prosthetics. To restore sight after retinal degeneration, one approach is to express light-sensitive proteins in remaining cells. Here the authors combine a light-sensitive engineered G protein-coupled receptor and ion channels to restore ON and OFF responses as well as superior visual pattern discrimination.
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82
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Van Gelder RN. Toward the Miracle of Retinal Reanimation. Ophthalmology 2017; 124:1723-1725. [PMID: 29157422 DOI: 10.1016/j.ophtha.2017.08.021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Revised: 08/15/2017] [Accepted: 08/16/2017] [Indexed: 10/18/2022] Open
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83
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Chaffiol A, Caplette R, Jaillard C, Brazhnikova E, Desrosiers M, Dubus E, Duhamel L, Macé E, Marre O, Benoit P, Hantraye P, Bemelmans AP, Bamberg E, Duebel J, Sahel JA, Picaud S, Dalkara D. A New Promoter Allows Optogenetic Vision Restoration with Enhanced Sensitivity in Macaque Retina. Mol Ther 2017; 25:2546-2560. [PMID: 28807567 PMCID: PMC5675708 DOI: 10.1016/j.ymthe.2017.07.011] [Citation(s) in RCA: 92] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 07/15/2017] [Accepted: 07/16/2017] [Indexed: 01/28/2023] Open
Abstract
The majority of inherited retinal degenerations converge on the phenotype of photoreceptor cell death. Second- and third-order neurons are spared in these diseases, making it possible to restore retinal light responses using optogenetics. Viral expression of channelrhodopsin in the third-order neurons under ubiquitous promoters was previously shown to restore visual function, albeit at light intensities above illumination safety thresholds. Here, we report (to our knowledge, for the first time) activation of macaque retinas, up to 6 months post-injection, using channelrhodopsin-Ca2+-permeable channelrhodopsin (CatCh) at safe light intensities. High-level CatCh expression was achieved due to a new promoter based on the regulatory region of the gamma-synuclein gene (SNCG) allowing strong expression in ganglion cells across species. Our promoter, in combination with clinically proven adeno-associated virus 2 (AAV2), provides CatCh expression in peri-foveolar ganglion cells responding robustly to light under the illumination safety thresholds for the human eye. On the contrary, the threshold of activation and the proportion of unresponsive cells were much higher when a ubiquitous promoter (cytomegalovirus [CMV]) was used to express CatCh. The results of our study suggest that the inclusion of optimized promoters is key in the path to clinical translation of optogenetics.
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Affiliation(s)
- Antoine Chaffiol
- INSERM U968, Institut de la Vision, 75012 Paris, France; UMRS968, Institut de la Vision, Sorbonne Universités, Pierre et Marie Curie University (UPMC) University Paris 06, 75012 Paris, France; Centre National de la Recherche Scientifique (CNRS) UMR7210, Institut de la Vision, 75012 Paris, France
| | - Romain Caplette
- INSERM U968, Institut de la Vision, 75012 Paris, France; UMRS968, Institut de la Vision, Sorbonne Universités, Pierre et Marie Curie University (UPMC) University Paris 06, 75012 Paris, France; Centre National de la Recherche Scientifique (CNRS) UMR7210, Institut de la Vision, 75012 Paris, France
| | - Céline Jaillard
- INSERM U968, Institut de la Vision, 75012 Paris, France; UMRS968, Institut de la Vision, Sorbonne Universités, Pierre et Marie Curie University (UPMC) University Paris 06, 75012 Paris, France; Centre National de la Recherche Scientifique (CNRS) UMR7210, Institut de la Vision, 75012 Paris, France
| | - Elena Brazhnikova
- INSERM U968, Institut de la Vision, 75012 Paris, France; UMRS968, Institut de la Vision, Sorbonne Universités, Pierre et Marie Curie University (UPMC) University Paris 06, 75012 Paris, France; Centre National de la Recherche Scientifique (CNRS) UMR7210, Institut de la Vision, 75012 Paris, France
| | - Mélissa Desrosiers
- INSERM U968, Institut de la Vision, 75012 Paris, France; UMRS968, Institut de la Vision, Sorbonne Universités, Pierre et Marie Curie University (UPMC) University Paris 06, 75012 Paris, France; Centre National de la Recherche Scientifique (CNRS) UMR7210, Institut de la Vision, 75012 Paris, France
| | - Elisabeth Dubus
- INSERM U968, Institut de la Vision, 75012 Paris, France; UMRS968, Institut de la Vision, Sorbonne Universités, Pierre et Marie Curie University (UPMC) University Paris 06, 75012 Paris, France; Centre National de la Recherche Scientifique (CNRS) UMR7210, Institut de la Vision, 75012 Paris, France
| | - Laëtitia Duhamel
- INSERM U968, Institut de la Vision, 75012 Paris, France; UMRS968, Institut de la Vision, Sorbonne Universités, Pierre et Marie Curie University (UPMC) University Paris 06, 75012 Paris, France; Centre National de la Recherche Scientifique (CNRS) UMR7210, Institut de la Vision, 75012 Paris, France
| | - Emilie Macé
- INSERM U968, Institut de la Vision, 75012 Paris, France; UMRS968, Institut de la Vision, Sorbonne Universités, Pierre et Marie Curie University (UPMC) University Paris 06, 75012 Paris, France; Centre National de la Recherche Scientifique (CNRS) UMR7210, Institut de la Vision, 75012 Paris, France
| | - Olivier Marre
- INSERM U968, Institut de la Vision, 75012 Paris, France; UMRS968, Institut de la Vision, Sorbonne Universités, Pierre et Marie Curie University (UPMC) University Paris 06, 75012 Paris, France; Centre National de la Recherche Scientifique (CNRS) UMR7210, Institut de la Vision, 75012 Paris, France
| | - Patrick Benoit
- Sanofi Ophthalmology Unit, 17 rue Moreau, 75012 Paris, France
| | - Philippe Hantraye
- Département des Sciences du Vivant (DSV), MIRCen, Institut d'Imagerie Biomédicale (I2BM), Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Fontenay-aux-Roses 92260, France; Neurodegenerative Diseases Laboratory, CNRS UMR9199, Université Paris-Sud, Université Paris-Saclay, Fontenay-aux-Roses 92260, France
| | - Alexis-Pierre Bemelmans
- Département des Sciences du Vivant (DSV), MIRCen, Institut d'Imagerie Biomédicale (I2BM), Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Fontenay-aux-Roses 92260, France; Neurodegenerative Diseases Laboratory, CNRS UMR9199, Université Paris-Sud, Université Paris-Saclay, Fontenay-aux-Roses 92260, France
| | - Ernst Bamberg
- Department of Biophysical Chemistry, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
| | - Jens Duebel
- INSERM U968, Institut de la Vision, 75012 Paris, France; UMRS968, Institut de la Vision, Sorbonne Universités, Pierre et Marie Curie University (UPMC) University Paris 06, 75012 Paris, France; Centre National de la Recherche Scientifique (CNRS) UMR7210, Institut de la Vision, 75012 Paris, France.
| | - José-Alain Sahel
- INSERM U968, Institut de la Vision, 75012 Paris, France; UMRS968, Institut de la Vision, Sorbonne Universités, Pierre et Marie Curie University (UPMC) University Paris 06, 75012 Paris, France; Centre National de la Recherche Scientifique (CNRS) UMR7210, Institut de la Vision, 75012 Paris, France; CHNO des Quinze-Vingts, DHU Sight Restore, INSERM-DHOS CIC, 28 rue de Charenton, 75012 Paris, France; Fondation Ophtalmologique Adolphe de Rothschild, 75019 Paris, France.
| | - Serge Picaud
- INSERM U968, Institut de la Vision, 75012 Paris, France; UMRS968, Institut de la Vision, Sorbonne Universités, Pierre et Marie Curie University (UPMC) University Paris 06, 75012 Paris, France; Centre National de la Recherche Scientifique (CNRS) UMR7210, Institut de la Vision, 75012 Paris, France.
| | - Deniz Dalkara
- INSERM U968, Institut de la Vision, 75012 Paris, France; UMRS968, Institut de la Vision, Sorbonne Universités, Pierre et Marie Curie University (UPMC) University Paris 06, 75012 Paris, France; Centre National de la Recherche Scientifique (CNRS) UMR7210, Institut de la Vision, 75012 Paris, France.
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84
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Dias MF, Joo K, Kemp JA, Fialho SL, da Silva Cunha A, Woo SJ, Kwon YJ. Molecular genetics and emerging therapies for retinitis pigmentosa: Basic research and clinical perspectives. Prog Retin Eye Res 2017; 63:107-131. [PMID: 29097191 DOI: 10.1016/j.preteyeres.2017.10.004] [Citation(s) in RCA: 259] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 10/19/2017] [Accepted: 10/25/2017] [Indexed: 02/06/2023]
Abstract
Retinitis Pigmentosa (RP) is a hereditary retinopathy that affects about 2.5 million people worldwide. It is characterized with progressive loss of rods and cones and causes severe visual dysfunction and eventual blindness in bilateral eyes. In addition to more than 3000 genetic mutations from about 70 genes, a wide genetic overlap with other types of retinal dystrophies has been reported with RP. This diversity of genetic pathophysiology makes treatment extremely challenging. Although therapeutic attempts have been made using various pharmacologic agents (neurotrophic factors, antioxidants, and anti-apoptotic agents), most are not targeted to the fundamental cause of RP, and their clinical efficacy has not been clearly proven. Current therapies for RP in ongoing or completed clinical trials include gene therapy, cell therapy, and retinal prostheses. Gene therapy, a strategy to correct the genetic defects using viral or non-viral vectors, has the potential to achieve definitive treatment by replacing or silencing a causative gene. Among many clinical trials of gene therapy for hereditary retinal diseases, a phase 3 clinical trial of voretigene neparvovec (AAV2-hRPE65v2, Luxturna) recently showed significant efficacy for RPE65-mediated inherited retinal dystrophy including Leber congenital amaurosis and RP. It is about to be approved as the first ocular gene therapy biologic product. Despite current limitations such as limited target genes and indicated patients, modest efficacy, and the invasive administration method, development in gene editing technology and novel gene delivery carriers make gene therapy a promising therapeutic modality for RP and other hereditary retinal dystrophies in the future.
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Affiliation(s)
- Marina França Dias
- School of Pharmacy, Federal University of Minas Gerais, Belo Horizonte, Brazil; Department of Pharmaceutical Sciences, University of California, Irvine, CA, USA
| | - Kwangsic Joo
- Department of Ophthalmology, Seoul National University Bundang Hospital, Seongnam, Republic of Korea
| | - Jessica A Kemp
- Department of Pharmaceutical Sciences, University of California, Irvine, CA, USA
| | - Silvia Ligório Fialho
- Pharmaceutical Research and Development, Ezequiel Dias Foundation, Belo Horizonte, Brazil
| | | | - Se Joon Woo
- Department of Pharmaceutical Sciences, University of California, Irvine, CA, USA; Department of Ophthalmology, Seoul National University Bundang Hospital, Seongnam, Republic of Korea.
| | - Young Jik Kwon
- Department of Pharmaceutical Sciences, University of California, Irvine, CA, USA; Department of Chemical Engineering and Materials Sciences, University of California, Irvine, CA, USA; Department of Biomedical Engineering, University of California, Irvine, CA, USA; Department of Molecular Biology and Biochemistry, University of California, Irvine, CA, USA.
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85
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Kumar A, Tan A, Wong J, Spagnoli JC, Lam J, Blevins BD, G N, Thorne L, Ashkan K, Xie J, Liu H. Nanotechnology for Neuroscience: Promising Approaches for Diagnostics, Therapeutics and Brain Activity Mapping. ADVANCED FUNCTIONAL MATERIALS 2017; 27:1700489. [PMID: 30853878 PMCID: PMC6404766 DOI: 10.1002/adfm.201700489] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Unlocking the secrets of the brain is a task fraught with complexity and challenge - not least due to the intricacy of the circuits involved. With advancements in the scale and precision of scientific technologies, we are increasingly equipped to explore how these components interact to produce a vast range of outputs that constitute function and disease. Here, an insight is offered into key areas in which the marriage of neuroscience and nanotechnology has revolutionized the industry. The evolution of ever more sophisticated nanomaterials culminates in network-operant functionalized agents. In turn, these materials contribute to novel diagnostic and therapeutic strategies, including drug delivery, neuroprotection, neural regeneration, neuroimaging and neurosurgery. Further, the entrance of nanotechnology into future research arenas including optogenetics, molecular/ion sensing and monitoring, and piezoelectric effects is discussed. Finally, considerations in nanoneurotoxicity, the main barrier to clinical translation, are reviewed, and direction for future perspectives is provided.
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Affiliation(s)
- Anil Kumar
- State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China
| | - Aaron Tan
- UCL Medical School, University College London (UCL), London, United Kingdom
| | - Joanna Wong
- Imperial College School of Medicine, Imperial College London,London, United Kingdom
| | - Jonathan Clayton Spagnoli
- Department of Chemistry, Bio-Imaging Research Center, University of Georgia, Athens, Georgia 30602, United States
| | - James Lam
- UCL Medical School, University College London (UCL), London, United Kingdom
| | - Brianna Diane Blevins
- Department of Chemistry, Bio-Imaging Research Center, University of Georgia, Athens, Georgia 30602, United States
| | - Natasha G
- UCL Medical School, University College London (UCL), London, United Kingdom
| | - Lewis Thorne
- Department of Neurosurgery, National Hospital for Neurology and Neurosurgery, Queen Square, London, United Kingdom
| | - Keyoumars Ashkan
- Department of Neurosurgery, King's College Hospital NHS Foundation Trust, King's College London, London, United Kingdom
| | - Jin Xie
- Department of Chemistry, Bio-Imaging Research Center, University of Georgia, Athens, Georgia 30602, United States
| | - Hong Liu
- State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China
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86
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Yan B, Nirenberg S. An Embedded Real-Time Processing Platform for Optogenetic Neuroprosthetic Applications. IEEE Trans Neural Syst Rehabil Eng 2017; 26:233-243. [PMID: 29035219 DOI: 10.1109/tnsre.2017.2763130] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Optogenetics offers a powerful new approach for controlling neural circuits. It has numerous applications in both basic and clinical science. These applications require stimulating devices with small processors that can perform real-time neural signal processing, deliver high-intensity light with high spatial and temporal resolution, and do not consume a lot of power. In this paper, we demonstrate the implementation of neuronal models in a platform consisting of an embedded system module and a portable digital light processing projector. As a replacement for damaged neural circuitry, the embedded module processes neural signals and then directs the projector to optogenetically activate a downstream neural pathway. We present a design in the context of stimulating circuits in the visual system, but the approach is feasible for a broad range of biomedical applications.
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87
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De Silva SR, Barnard AR, Hughes S, Tam SKE, Martin C, Singh MS, Barnea-Cramer AO, McClements ME, During MJ, Peirson SN, Hankins MW, MacLaren RE. Long-term restoration of visual function in end-stage retinal degeneration using subretinal human melanopsin gene therapy. Proc Natl Acad Sci U S A 2017; 114:11211-11216. [PMID: 28973921 PMCID: PMC5651734 DOI: 10.1073/pnas.1701589114] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Optogenetic strategies to restore vision in patients who are blind from end-stage retinal degenerations aim to render remaining retinal cells light sensitive once photoreceptors are lost. Here, we assessed long-term functional outcomes following subretinal delivery of the human melanopsin gene (OPN4) in the rd1 mouse model of retinal degeneration using an adeno-associated viral vector. Ectopic expression of OPN4 using a ubiquitous promoter resulted in cellular depolarization and ganglion cell action potential firing. Restoration of the pupil light reflex, behavioral light avoidance, and the ability to perform a task requiring basic image recognition were restored up to 13 mo following injection. These data suggest that melanopsin gene therapy via a subretinal route may be a viable and stable therapeutic option for the treatment of end-stage retinal degeneration in humans.
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Affiliation(s)
- Samantha R De Silva
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, National Institute for Health Research Biomedical Research Centre, Oxford OX3 9DU, United Kingdom
| | - Alun R Barnard
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, National Institute for Health Research Biomedical Research Centre, Oxford OX3 9DU, United Kingdom
| | - Steven Hughes
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, National Institute for Health Research Biomedical Research Centre, Oxford OX3 9DU, United Kingdom
| | - Shu K E Tam
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, National Institute for Health Research Biomedical Research Centre, Oxford OX3 9DU, United Kingdom
| | - Chris Martin
- Department of Psychology, The University of Sheffield, Sheffield S1 2LT, United Kingdom
| | - Mandeep S Singh
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, National Institute for Health Research Biomedical Research Centre, Oxford OX3 9DU, United Kingdom
| | - Alona O Barnea-Cramer
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, National Institute for Health Research Biomedical Research Centre, Oxford OX3 9DU, United Kingdom
| | - Michelle E McClements
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, National Institute for Health Research Biomedical Research Centre, Oxford OX3 9DU, United Kingdom
| | | | - Stuart N Peirson
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, National Institute for Health Research Biomedical Research Centre, Oxford OX3 9DU, United Kingdom
| | - Mark W Hankins
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, National Institute for Health Research Biomedical Research Centre, Oxford OX3 9DU, United Kingdom;
| | - Robert E MacLaren
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, National Institute for Health Research Biomedical Research Centre, Oxford OX3 9DU, United Kingdom;
- Moorfields Eye Hospital, National Institute for Health Research Biomedical Research Centre, London EC1V 2PD, United Kingdom
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88
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Wright W, Gajjeraman S, Batabyal S, Pradhan S, Bhattacharya S, Mahapatra V, Tripathy A, Mohanty S. Restoring vision in mice with retinal degeneration using multicharacteristic opsin. NEUROPHOTONICS 2017; 4:041412. [PMID: 28840163 DOI: 10.1117/1.nph.4.4.041412] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 04/02/2017] [Accepted: 07/24/2017] [Indexed: 06/07/2023]
Abstract
Retinal degenerative diseases, such as retinitis pigmentosa (RP) and dry age-related macular degeneration, have led to loss of vision in millions of individuals. Currently, no surgical or medical treatment is available, although optogenetic therapies are in clinical development. We demonstrate vision restoration using multicharacteristics opsin (MCO1) in animal models with degenerated retina. MCO1 is reliably delivered to specific retinal cells via intravitreal injection of adeno-associated virus (vMCO1), leading to significant improvement in visually guided behavior conducted using a radial arm water maze. The time to reach the platform and the number of error arms decreased significantly after delivery of MCO1. Notably, the improvement in visually guided behavior was observed even at light intensity levels orders of magnitude lower than that required for channelrhodopsin-2 opsin. Viability of vMCO1-treated retina is not compromised by chronic light exposure. Safe virus-mediated MCO1 delivery has potential for effective gene therapy of diverse retinal degenerations in patients.
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Affiliation(s)
- Weldon Wright
- NanoScope Technologies LLC, Bedford, Texas, United States
| | | | | | - Sanjay Pradhan
- NanoScope Technologies LLC, Bedford, Texas, United States
| | | | - Vasu Mahapatra
- NanoScope Technologies LLC, Bedford, Texas, United States
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89
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Wright W, Gajjeraman S, Batabyal S, Pradhan S, Bhattacharya S, Mahapatra V, Tripathy A, Mohanty S. Restoring vision in mice with retinal degeneration using multicharacteristic opsin. NEUROPHOTONICS 2017; 4:041505. [PMID: 28948190 PMCID: PMC5603575 DOI: 10.1117/1.nph.4.4.041505] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2017] [Accepted: 07/24/2017] [Indexed: 05/03/2023]
Abstract
Retinal degenerative diseases, such as retinitis pigmentosa (RP) and dry age-related macular degeneration, have led to loss of vision in millions of individuals. Currently, no surgical or medical treatment is available, although optogenetic therapies are in clinical development. We demonstrate vision restoration using multicharacteristics opsin (MCO1) in animal models with degenerated retina. MCO1 is reliably delivered to specific retinal cells via intravitreal injection of adeno-associated virus (vMCO1), leading to significant improvement in visually guided behavior conducted using a radial arm water maze. The time to reach the platform and the number of error arms decreased significantly after delivery of MCO1. Notably, the improvement in visually guided behavior was observed even at light intensity levels orders of magnitude lower than that required for channelrhodopsin-2 opsin. Viability of vMCO1-treated retina is not compromised by chronic light exposure. Safe virus-mediated MCO1 delivery has potential for effective gene therapy of diverse retinal degenerations in patients.
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Affiliation(s)
- Weldon Wright
- NanoScope Technologies LLC, Bedford, Texas,
United States
| | | | | | - Sanjay Pradhan
- NanoScope Technologies LLC, Bedford, Texas,
United States
| | | | - Vasu Mahapatra
- NanoScope Technologies LLC, Bedford, Texas,
United States
| | | | - Samarendra Mohanty
- NanoScope Technologies LLC, Bedford, Texas,
United States
- Address all correspondence to: Samarendra Mohanty,
E-mail:
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90
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Affiliation(s)
- Arthur Planul
- Inserm, Institut de la Vision, UMR S968, 75012 Paris, France;,
- Sorbonne Universités, UPMC Université Paris 6, UMR S968, 75012 Paris, France
- CNRS, UMR 7210, 75012 Paris, France
| | - Deniz Dalkara
- Inserm, Institut de la Vision, UMR S968, 75012 Paris, France;,
- Sorbonne Universités, UPMC Université Paris 6, UMR S968, 75012 Paris, France
- CNRS, UMR 7210, 75012 Paris, France
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91
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Long-term expression of melanopsin and channelrhodopsin causes no gross alterations in the dystrophic dog retina. Gene Ther 2017; 24:735-741. [PMID: 28880021 DOI: 10.1038/gt.2017.63] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 07/05/2017] [Accepted: 07/10/2017] [Indexed: 01/25/2023]
Abstract
Several preclinical studies have investigated the potential of algal channelrhodopsin and human melanopsin as optogenetic tools for vision restoration. In the present study, we assessed the potentially deleterious effects of long-term expression of these optogenes on the diseased retina in a large animal model of retinal degeneration, the RPE65-deficient Briard dog model of Leber congenital amaurosis. Intravitreal injection of adeno-associated virus vectors expressing channelrhodopsin and melanopsin had no effect on retinal thickness over a 16-month period post injection. Our data support the safety of the optogenetic approach for the treatment of blindness.
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92
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Boye SE, Alexander JJ, Witherspoon CD, Boye SL, Peterson JJ, Clark ME, Sandefer KJ, Girkin CA, Hauswirth WW, Gamlin PD. Highly Efficient Delivery of Adeno-Associated Viral Vectors to the Primate Retina. Hum Gene Ther 2017; 27:580-97. [PMID: 27439313 DOI: 10.1089/hum.2016.085] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Adeno-associated virus (AAV) has emerged as the preferred vector for targeting gene expression to the retina. Subretinally injected AAV can efficiently transduce retinal pigment epithelium and photoreceptors in primate retina. Inner and middle primate retina can be transduced by intravitreally delivered AAV, but with low efficiency. This is due to dilution of vector, potential neutralization of capsid because it is not confined to the immune-privileged retinal compartment, and the presence of the inner limiting membrane (ILM), a barrier separating the vitreous from the neural retina. We here describe a novel "subILM" injection method that addresses all three issues. Specifically, vector is placed in a surgically induced, hydrodissected space between the ILM and neural retina. In an initial experiment, we injected viscoelastic (Healon(®)), a substance we confirmed was biocompatible with AAV, to create a subILM bleb and subsequently injected AAV2-GFP into the bleb after irrigation with basic salt solution. For later experiments, we used a Healon-AAV mixture to place single, subILM injections. In all cases, subILM delivery of AAV was well tolerated-no inflammation or gross structural changes were observed by ophthalmological examination or optical coherence tomography. In-life fluorescence imaging revealed profound transgene expression within the area of the subILM injection bleb that persisted for the study duration. Uniform and extensive transduction of retinal ganglion cells (RGCs) was achieved in the areas beneath the subILM bleb. Transduction of Müller glia, ON bipolar cells, and photoreceptors was also observed. Robust central labeling from green fluorescent protein-expressing RGCs confirmed their continued survival, and was observed in the lateral geniculate nucleus, the superior colliculus, and the pretectum. Our results confirm that the ILM is a major barrier to transduction by AAV in primate retina and that, when it is circumvented, the efficiency and depth to which AAV2 promotes transduction of multiple retinal cell classes are greatly enhanced.
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Affiliation(s)
- Shannon E Boye
- 1 Department of Ophthalmology, University of Florida College of Medicine , Gainesville, Florida
| | - John J Alexander
- 2 Department of Human Genetics, Emory University , Atlanta, Georgia
| | - C Douglas Witherspoon
- 3 Department of Ophthalmology, University of Alabama at Birmingham , Birmingham, Alabama
| | - Sanford L Boye
- 1 Department of Ophthalmology, University of Florida College of Medicine , Gainesville, Florida
| | - James J Peterson
- 1 Department of Ophthalmology, University of Florida College of Medicine , Gainesville, Florida
| | - Mark E Clark
- 3 Department of Ophthalmology, University of Alabama at Birmingham , Birmingham, Alabama
| | - Kristen J Sandefer
- 4 Department of Neurology, University of Alabama at Birmingham , Birmingham, Alabama
| | - Chris A Girkin
- 3 Department of Ophthalmology, University of Alabama at Birmingham , Birmingham, Alabama
| | - William W Hauswirth
- 1 Department of Ophthalmology, University of Florida College of Medicine , Gainesville, Florida
| | - Paul D Gamlin
- 3 Department of Ophthalmology, University of Alabama at Birmingham , Birmingham, Alabama
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93
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Govorunova EG, Sineshchekov OA, Li H, Spudich JL. Microbial Rhodopsins: Diversity, Mechanisms, and Optogenetic Applications. Annu Rev Biochem 2017; 86:845-872. [PMID: 28301742 PMCID: PMC5747503 DOI: 10.1146/annurev-biochem-101910-144233] [Citation(s) in RCA: 242] [Impact Index Per Article: 34.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Microbial rhodopsins are a family of photoactive retinylidene proteins widespread throughout the microbial world. They are notable for their diversity of function, using variations of a shared seven-transmembrane helix design and similar photochemical reactions to carry out distinctly different light-driven energy and sensory transduction processes. Their study has contributed to our understanding of how evolution modifies protein scaffolds to create new protein chemistry, and their use as tools to control membrane potential with light is fundamental to optogenetics for research and clinical applications. We review the currently known functions and present more in-depth assessment of three functionally and structurally distinct types discovered over the past two years: (a) anion channelrhodopsins (ACRs) from cryptophyte algae, which enable efficient optogenetic neural suppression; (b) cryptophyte cation channelrhodopsins (CCRs), structurally distinct from the green algae CCRs used extensively for neural activation and from cryptophyte ACRs; and
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Affiliation(s)
- Elena G Govorunova
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas 77030; , , ,
| | - Oleg A Sineshchekov
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas 77030; , , ,
| | - Hai Li
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas 77030; , , ,
| | - John L Spudich
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas 77030; , , ,
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94
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Cideciyan AV, Roman AJ, Jacobson SG, Yan B, Pascolini M, Charng J, Pajaro S, Nirenberg S. Developing an Outcome Measure With High Luminance for Optogenetics Treatment of Severe Retinal Degenerations and for Gene Therapy of Cone Diseases. Invest Ophthalmol Vis Sci 2017; 57:3211-21. [PMID: 27309625 PMCID: PMC4928698 DOI: 10.1167/iovs.16-19586] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To present stimuli with varied sizes, colors, and patterns over a large range of luminance. Methods The filter bar used in scotopic MP1 was replaced with a custom slide-in tray that introduces light from an external projector driven by an additional computer. MP1 software was modified to provide retinal tracking information to the computer driving the projector. Retinal tracking performance was evaluated by imaging the system input and the output simultaneously with a high-speed video system. Spatial resolution was measured with achromatic and chromatic grating/background combinations over scotopic and photopic ranges. Results The range of retinal illuminance achievable by the modification was up to 6.8 log photopic Trolands (phot-Td); however, in the current work, only a lower range over −4 to +3 log phot-Td was tested in human subjects. Optical magnification was optimized for low-vision testing with gratings from 4.5 to 0.2 cyc/deg. In normal subjects, spatial resolution driven by rods, short wavelength-sensitive (S-) cones, and long/middle wavelength-sensitive (L/M-) cones was obtained by the choice of adapting conditions and wavelengths of grating and background. Data from a patient with blue cone monochromacy was used to confirm mediation. Conclusions The modified MP1 can be developed into an outcome measure for treatments in patients with severe retinal degeneration, very low vision, and abnormal eye movements such as those for whom treatment with optogenetics is planned, as well as for patients with cone disorders such as blue cone monochromacy for whom treatment with gene therapy is planned to improve L/M-cone function above a normal complement of rod and S-cone function.
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Affiliation(s)
- Artur V Cideciyan
- Scheie Eye Institute Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Alejandro J Roman
- Scheie Eye Institute Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Samuel G Jacobson
- Scheie Eye Institute Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Boyuan Yan
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, New York, United States
| | | | - Jason Charng
- Scheie Eye Institute Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | | | - Sheila Nirenberg
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, New York, United States
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95
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Utilizing Zebrafish Visual Behaviors in Drug Screening for Retinal Degeneration. Int J Mol Sci 2017; 18:ijms18061185. [PMID: 28574477 PMCID: PMC5486008 DOI: 10.3390/ijms18061185] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2017] [Revised: 05/14/2017] [Accepted: 05/16/2017] [Indexed: 12/15/2022] Open
Abstract
Zebrafish are a popular vertebrate model in drug discovery. They produce a large number of small and rapidly-developing embryos. These embryos display rich visual-behaviors that can be used to screen drugs for treating retinal degeneration (RD). RD comprises blinding diseases such as Retinitis Pigmentosa, which affects 1 in 4000 people. This disease has no definitive cure, emphasizing an urgency to identify new drugs. In this review, we will discuss advantages, challenges, and research developments in using zebrafish behaviors to screen drugs in vivo. We will specifically discuss a visual-motor response that can potentially expedite discovery of new RD drugs.
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96
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van Wyk M, Hulliger EC, Girod L, Ebneter A, Kleinlogel S. Present Molecular Limitations of ON-Bipolar Cell Targeted Gene Therapy. Front Neurosci 2017; 11:161. [PMID: 28424574 PMCID: PMC5372788 DOI: 10.3389/fnins.2017.00161] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 03/13/2017] [Indexed: 11/13/2022] Open
Abstract
Recent studies have demonstrated the safety and efficacy of ocular gene therapy based on adeno-associated viral vectors (AAVs). Accordingly, a surge in promising new gene therapies is entering clinical trials, including the first optogenetic therapy for vision restoration. To date, optogenetic therapies for vision restoration target either the retinal ganglion cells (GCs) or presynaptic ON-bipolar cells (OBCs). Initiating light responses at the level of the OBCs has significant advantages over optogenetic activation of GCs. For example, important neural circuitries in the inner retina, which shape the receptive fields of GCs, remain intact when activating the OBCs. Current drawbacks of AAV-mediated gene therapies targeting OBCs include (1) a low transduction efficiency, (2) off-target expression in unwanted cell populations, and (3) a poor performance in human tissue compared to the murine retina. Here, we examined side-by-side the performance of three state-of-the art AAV capsid variants, AAV7m8, AAVBP2, and AAV7m8(Y444F) in combination with the 4xGRM6-SV40 promoter construct in the healthy and degenerated mouse retina and in human post-mortem retinal explants. We find that (1) the 4xGRM6-SV40 promoter is not OBC specific, (2) that all AAV variants possess broad cellular transduction patterns, with differences between the transduction patterns of capsid variants AAVBP2 and AAV7m8 and, most importantly, (3) that all vectors target OBCs in healthy tissue but not in the degenerated rd1 mouse model, potentially limiting the possibilities for an OBC-targeted optogenetic therapy for vision restoration in the blind.
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Affiliation(s)
- Michiel van Wyk
- Institute of Physiology, University of BernBern, Switzerland
| | | | - Lara Girod
- Institute of Physiology, University of BernBern, Switzerland
| | - Andreas Ebneter
- Department of Ophthalmology, Inselspital, Bern University Hospital, University of BernBern, Switzerland
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97
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Sengupta A, Chaffiol A, Macé E, Caplette R, Desrosiers M, Lampič M, Forster V, Marre O, Lin JY, Sahel JA, Picaud S, Dalkara D, Duebel J. Red-shifted channelrhodopsin stimulation restores light responses in blind mice, macaque retina, and human retina. EMBO Mol Med 2016; 8:1248-1264. [PMID: 27679671 PMCID: PMC5090658 DOI: 10.15252/emmm.201505699] [Citation(s) in RCA: 113] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Revised: 08/09/2016] [Accepted: 08/11/2016] [Indexed: 01/31/2023] Open
Abstract
Targeting the photosensitive ion channel channelrhodopsin-2 (ChR2) to the retinal circuitry downstream of photoreceptors holds promise in treating vision loss caused by retinal degeneration. However, the high intensity of blue light necessary to activate channelrhodopsin-2 exceeds the safety threshold of retinal illumination because of its strong potential to induce photochemical damage. In contrast, the damage potential of red-shifted light is vastly lower than that of blue light. Here, we show that a red-shifted channelrhodopsin (ReaChR), delivered by AAV injections in blind rd1 mice, enables restoration of light responses at the retinal, cortical, and behavioral levels, using orange light at intensities below the safety threshold for the human retina. We further show that postmortem macaque retinae infected with AAV-ReaChR can respond with spike trains to orange light at safe intensities. Finally, to directly address the question of translatability to human subjects, we demonstrate for the first time, AAV- and lentivirus-mediated optogenetic spike responses in ganglion cells of the postmortem human retina.
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Affiliation(s)
- Abhishek Sengupta
- INSERM U968, Paris, France
- Sorbonne Universités UPMC Univ Paris 06 UMR_S 968 Institut de la Vision, Paris, France
- CNRS UMR_7210, Paris, France
| | - Antoine Chaffiol
- INSERM U968, Paris, France
- Sorbonne Universités UPMC Univ Paris 06 UMR_S 968 Institut de la Vision, Paris, France
- CNRS UMR_7210, Paris, France
| | - Emilie Macé
- INSERM U968, Paris, France
- Sorbonne Universités UPMC Univ Paris 06 UMR_S 968 Institut de la Vision, Paris, France
- CNRS UMR_7210, Paris, France
| | - Romain Caplette
- INSERM U968, Paris, France
- Sorbonne Universités UPMC Univ Paris 06 UMR_S 968 Institut de la Vision, Paris, France
- CNRS UMR_7210, Paris, France
| | - Mélissa Desrosiers
- INSERM U968, Paris, France
- Sorbonne Universités UPMC Univ Paris 06 UMR_S 968 Institut de la Vision, Paris, France
- CNRS UMR_7210, Paris, France
| | - Maruša Lampič
- INSERM U968, Paris, France
- Sorbonne Universités UPMC Univ Paris 06 UMR_S 968 Institut de la Vision, Paris, France
- CNRS UMR_7210, Paris, France
| | - Valérie Forster
- INSERM U968, Paris, France
- Sorbonne Universités UPMC Univ Paris 06 UMR_S 968 Institut de la Vision, Paris, France
- CNRS UMR_7210, Paris, France
| | - Olivier Marre
- INSERM U968, Paris, France
- Sorbonne Universités UPMC Univ Paris 06 UMR_S 968 Institut de la Vision, Paris, France
- CNRS UMR_7210, Paris, France
| | - John Y Lin
- School of Medicine, University of Tasmania, Hobart, Tasmania, Australia
| | - José-Alain Sahel
- INSERM U968, Paris, France
- Sorbonne Universités UPMC Univ Paris 06 UMR_S 968 Institut de la Vision, Paris, France
- CNRS UMR_7210, Paris, France
- Hôpital des Quinze-Vingts, Paris, France
| | - Serge Picaud
- INSERM U968, Paris, France
- Sorbonne Universités UPMC Univ Paris 06 UMR_S 968 Institut de la Vision, Paris, France
- CNRS UMR_7210, Paris, France
| | - Deniz Dalkara
- INSERM U968, Paris, France
- Sorbonne Universités UPMC Univ Paris 06 UMR_S 968 Institut de la Vision, Paris, France
- CNRS UMR_7210, Paris, France
| | - Jens Duebel
- INSERM U968, Paris, France
- Sorbonne Universités UPMC Univ Paris 06 UMR_S 968 Institut de la Vision, Paris, France
- CNRS UMR_7210, Paris, France
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98
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De Silva SR, Charbel Issa P, Singh MS, Lipinski DM, Barnea-Cramer AO, Walker NJ, Barnard AR, Hankins MW, MacLaren RE. Single residue AAV capsid mutation improves transduction of photoreceptors in the Abca4 -/- mouse and bipolar cells in the rd1 mouse and human retina ex vivo. Gene Ther 2016; 23:767-774. [PMID: 27416076 PMCID: PMC5097463 DOI: 10.1038/gt.2016.54] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Revised: 04/12/2016] [Accepted: 04/20/2016] [Indexed: 02/08/2023]
Abstract
Gene therapy using adeno-associated viral (AAV) vectors for the treatment of retinal degenerations has shown safety and efficacy in clinical trials. However, very high levels of vector expression may be necessary for the treatment of conditions such as Stargardt disease where a dual vector approach is potentially needed, or in optogenetic strategies for end-stage degeneration in order to achieve maximal light sensitivity. In this study, we assessed two vectors with single capsid mutations, rAAV2/2(Y444F) and rAAV2/8(Y733F) in their ability to transduce retina in the Abca4-/- and rd1 mouse models of retinal degeneration. We noted significantly increased photoreceptor transduction using rAAV2/8(Y733F) in the Abca4-/- mouse, in contrast to previous work where vectors tested in this model have shown low levels of photoreceptor transduction. Bipolar cell transduction was achieved following subretinal delivery of both vectors in the rd1 mouse, and via intravitreal delivery of rAAV2/2(Y444F). The successful use of rAAV2/8(Y733F) to target bipolar cells was further validated on human tissue using an ex vivo culture system of retinal explants. Capsid mutant AAV vectors transduce human retinal cells and may be particularly suited to treat retinal degenerations in which high levels of transgene expression are required.
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Affiliation(s)
- Samantha R De Silva
- Nuffield Laboratory of Ophthalmology, University of Oxford, NIHR Biomedical Research Centre, UK
| | - Peter Charbel Issa
- Nuffield Laboratory of Ophthalmology, University of Oxford, NIHR Biomedical Research Centre, UK
- Department of Ophthalmology, University of Bonn, Bonn, Germany
| | - Mandeep S Singh
- Nuffield Laboratory of Ophthalmology, University of Oxford, NIHR Biomedical Research Centre, UK
| | - Daniel M Lipinski
- Nuffield Laboratory of Ophthalmology, University of Oxford, NIHR Biomedical Research Centre, UK
| | - Alona O Barnea-Cramer
- Nuffield Laboratory of Ophthalmology, University of Oxford, NIHR Biomedical Research Centre, UK
| | - Nathan J Walker
- Nuffield Laboratory of Ophthalmology, University of Oxford, NIHR Biomedical Research Centre, UK
| | - Alun R Barnard
- Nuffield Laboratory of Ophthalmology, University of Oxford, NIHR Biomedical Research Centre, UK
| | - Mark W Hankins
- Nuffield Laboratory of Ophthalmology, University of Oxford, NIHR Biomedical Research Centre, UK
| | - Robert E MacLaren
- Nuffield Laboratory of Ophthalmology, University of Oxford, NIHR Biomedical Research Centre, UK
- Moorfields Eye Hospital, NIHR Biomedical Research Centre, UK
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99
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Petit L, Punzo C. Gene therapy approaches for the treatment of retinal disorders. DISCOVERY MEDICINE 2016; 22:221-229. [PMID: 27875674 PMCID: PMC5142441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
There is an impelling need to develop effective therapeutic strategies for patients with retinal disorders. Gleaning from the large quantity of information gathered over the past two decades on the mechanisms governing degeneration of the retina, it is now possible to devise innovative therapies based on retinal gene transfer. Different gene-based approaches are under active investigation. They include strategies to correct the specific genetic defect in inherited retinal diseases, strategies to delay the onset of blindness independently of the disease-causing mutations, and strategies to reactivate residual cells at late stages of the diseases. In this review, we discuss the status of application of these technologies, outlining the future therapeutic potential for many forms of retinal blinding diseases.
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Affiliation(s)
- Lolita Petit
- Department of Ophthalmology and Gene Therapy Center, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Claudio Punzo
- Department of Ophthalmology and Gene Therapy Center, University of Massachusetts Medical School, Worcester, Massachusetts, USA
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts, USA
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100
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Dampening Spontaneous Activity Improves the Light Sensitivity and Spatial Acuity of Optogenetic Retinal Prosthetic Responses. Sci Rep 2016; 6:33565. [PMID: 27650332 PMCID: PMC5030712 DOI: 10.1038/srep33565] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 08/19/2016] [Indexed: 01/19/2023] Open
Abstract
Retinitis pigmentosa is a progressive retinal dystrophy that causes irreversible visual impairment and blindness. Retinal prostheses currently represent the only clinically available vision-restoring treatment, but the quality of vision returned remains poor. Recently, it has been suggested that the pathological spontaneous hyperactivity present in dystrophic retinas may contribute to the poor quality of vision returned by retinal prosthetics by reducing the signal-to-noise ratio of prosthetic responses. Here, we investigated to what extent blocking this hyperactivity can improve optogenetic retinal prosthetic responses. We recorded activity from channelrhodopsin-expressing retinal ganglion cells in retinal wholemounts in a mouse model of retinitis pigmentosa. Sophisticated stimuli, inspired by those used in clinical visual assessment, were used to assess light sensitivity, contrast sensitivity and spatial acuity of optogenetic responses; in all cases these were improved after blocking spontaneous hyperactivity using meclofenamic acid, a gap junction blocker. Our results suggest that this approach significantly improves the quality of vision returned by retinal prosthetics, paving the way to novel clinical applications. Moreover, the improvements in sensitivity achieved by blocking spontaneous hyperactivity may extend the dynamic range of optogenetic retinal prostheses, allowing them to be used at lower light intensities such as those encountered in everyday life.
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