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Scalabrino ML, Thapa M, Wang T, Sampath AP, Chen J, Field GD. Late gene therapy limits the restoration of retinal function in a mouse model of retinitis pigmentosa. Nat Commun 2023; 14:8256. [PMID: 38086857 PMCID: PMC10716155 DOI: 10.1038/s41467-023-44063-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Accepted: 11/29/2023] [Indexed: 12/18/2023] Open
Abstract
Retinitis pigmentosa is an inherited photoreceptor degeneration that begins with rod loss followed by cone loss. This cell loss greatly diminishes vision, with most patients becoming legally blind. Gene therapies are being developed, but it is unknown how retinal function depends on the time of intervention. To uncover this dependence, we utilize a mouse model of retinitis pigmentosa capable of artificial genetic rescue. This model enables a benchmark of best-case gene therapy by removing variables that complicate answering this question. Complete genetic rescue was performed at 25%, 50%, and 70% rod loss (early, mid and late, respectively). Early and mid treatment restore retinal output to near wild-type levels. Late treatment retinas exhibit continued, albeit slowed, loss of sensitivity and signal fidelity among retinal ganglion cells, as well as persistent gliosis. We conclude that gene replacement therapies delivered after 50% rod loss are unlikely to restore visual function to normal. This is critical information for administering gene therapies to rescue vision.
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Affiliation(s)
- Miranda L Scalabrino
- Stein Eye Institute, Department of Ophthalmology, University of California, Los Angeles, CA, USA
- Department of Neurobiology, Duke University School of Medicine, Durham, NC, USA
| | - Mishek Thapa
- Stein Eye Institute, Department of Ophthalmology, University of California, Los Angeles, CA, USA
- Department of Neurobiology, Duke University School of Medicine, Durham, NC, USA
| | - Tian Wang
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Alapakkam P Sampath
- Stein Eye Institute, Department of Ophthalmology, University of California, Los Angeles, CA, USA
| | - Jeannie Chen
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Greg D Field
- Stein Eye Institute, Department of Ophthalmology, University of California, Los Angeles, CA, USA.
- Department of Neurobiology, Duke University School of Medicine, Durham, NC, USA.
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Kerschensteiner D. Losing, preserving, and restoring vision from neurodegeneration in the eye. Curr Biol 2023; 33:R1019-R1036. [PMID: 37816323 PMCID: PMC10575673 DOI: 10.1016/j.cub.2023.08.044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/12/2023]
Abstract
The retina is a part of the brain that sits at the back of the eye, looking out onto the world. The first neurons of the retina are the rod and cone photoreceptors, which convert changes in photon flux into electrical signals that are the basis of vision. Rods and cones are frequent targets of heritable neurodegenerative diseases that cause visual impairment, including blindness, in millions of people worldwide. This review summarizes the diverse genetic causes of inherited retinal degenerations (IRDs) and their convergence onto common pathogenic mechanisms of vision loss. Currently, there are few effective treatments for IRDs, but recent advances in disparate areas of biology and technology (e.g., genome editing, viral engineering, 3D organoids, optogenetics, semiconductor arrays) discussed here enable promising efforts to preserve and restore vision in IRD patients with implications for neurodegeneration in less approachable brain areas.
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Affiliation(s)
- Daniel Kerschensteiner
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Neuroscience, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Biomedical Engineering, Washington University School of Medicine, St. Louis, MO 63110, USA.
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Kamde SP, Anjankar A. Retinitis Pigmentosa: Pathogenesis, Diagnostic Findings, and Treatment. Cureus 2023; 15:e48006. [PMID: 38034182 PMCID: PMC10686897 DOI: 10.7759/cureus.48006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Accepted: 10/30/2023] [Indexed: 12/02/2023] Open
Abstract
Retinitis Pigmentosa (RP) is an inherited retinal dystrophy (IRD) that causes progressive visual loss. Patients suffering from RP have a substantial influence on their everyday activities, social contacts, and jobs, lowering their quality of life. Frequent referral delays, as well as the lack of a standard therapy for the majority of patients, contribute to the significant unmet demand for RP. Any retinal injury has the potential to result in total blindness and visual impairment. Despite the fact that there is no cure for RP, people can manage it using rehabilitation programs and low-vision gadgets. The purpose of this research is to characterize the expanding treatment landscape for RP, as well as the justification for advanced therapy medicinal products (ATMPs). Vitamin A supplements can help prevent the sluggish visual loss caused by a prevalent kind of RP. The presence of visual purple in the rods and the underlying vascular choroid causes the retina to look purplish red. The major portion of the retina damaged is the rod photoreceptor electric cell; the development of diverse diseases is progressive. Because of the retina's accessibility, immunological privilege, and compartmentalization, hereditary retinal diseases are amenable to cell and gene therapy. Therapeutic techniques that attempt to rescue photoreceptors (gene therapies) require the existence of non-functional target cells, but other therapies (cell therapies) do not require the presence of live photoreceptors. To provide successful therapy choices for RP patients at all disease phases, the development pipeline must be continually diversified and advanced, as well as ongoing efforts to encourage early patient identification and quick diagnosis. Future research will focus on avoiding vision loss in genetic eye illnesses and assisting patients in regaining their eyesight. Retinal implants, cell therapies, supplementary medications, and gene therapies may become common treatments for reducing vision loss in the future.
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Affiliation(s)
- Saakshi P Kamde
- Forensic Medicine, Jawaharlal Nehru Medical College, Datta Meghe Institute of Higher Education and Research, Wardha, IND
| | - Anil Anjankar
- Forensic Medicine, Jawaharlal Nehru Medical College, Datta Meghe Institute of Higher Education and Research, Wardha, IND
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Ellis EM, Paniagua AE, Scalabrino ML, Thapa M, Rathinavelu J, Jiao Y, Williams DS, Field GD, Fain GL, Sampath AP. Cones and cone pathways remain functional in advanced retinal degeneration. Curr Biol 2023; 33:1513-1522.e4. [PMID: 36977418 PMCID: PMC10133175 DOI: 10.1016/j.cub.2023.03.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 12/14/2022] [Accepted: 03/03/2023] [Indexed: 03/29/2023]
Abstract
Most defects causing retinal degeneration in retinitis pigmentosa (RP) are rod-specific mutations, but the subsequent degeneration of cones, which produces loss of daylight vision and high-acuity perception, is the most debilitating feature of the disease. To understand better why cones degenerate and how cone vision might be restored, we have made the first single-cell recordings of light responses from degenerating cones and retinal interneurons after most rods have died and cones have lost their outer-segment disk membranes and synaptic pedicles. We show that degenerating cones have functional cyclic-nucleotide-gated channels and can continue to give light responses, apparently produced by opsin localized either to small areas of organized membrane near the ciliary axoneme or distributed throughout the inner segment. Light responses of second-order horizontal and bipolar cells are less sensitive but otherwise resemble those of normal retina. Furthermore, retinal output as reflected in responses of ganglion cells is less sensitive but maintains spatiotemporal receptive fields at cone-mediated light levels. Together, these findings show that cones and their retinal pathways can remain functional even as degeneration is progressing, an encouraging result for future research aimed at enhancing the light sensitivity of residual cones to restore vision in patients with genetically inherited retinal degeneration.
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Affiliation(s)
- Erika M Ellis
- Department of Ophthalmology and Jules Stein Eye Institute, University of California, Los Angeles, Los Angeles, CA 90095-7000, USA
| | - Antonio E Paniagua
- Department of Ophthalmology and Jules Stein Eye Institute, University of California, Los Angeles, Los Angeles, CA 90095-7000, USA
| | - Miranda L Scalabrino
- Department of Ophthalmology and Jules Stein Eye Institute, University of California, Los Angeles, Los Angeles, CA 90095-7000, USA; Department of Neurobiology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Mishek Thapa
- Department of Ophthalmology and Jules Stein Eye Institute, University of California, Los Angeles, Los Angeles, CA 90095-7000, USA; Department of Neurobiology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Jay Rathinavelu
- Department of Neurobiology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Yuekan Jiao
- Department of Ophthalmology and Jules Stein Eye Institute, University of California, Los Angeles, Los Angeles, CA 90095-7000, USA
| | - David S Williams
- Department of Ophthalmology and Jules Stein Eye Institute, University of California, Los Angeles, Los Angeles, CA 90095-7000, USA.
| | - Greg D Field
- Department of Ophthalmology and Jules Stein Eye Institute, University of California, Los Angeles, Los Angeles, CA 90095-7000, USA; Department of Neurobiology, Duke University School of Medicine, Durham, NC 27710, USA.
| | - Gordon L Fain
- Department of Ophthalmology and Jules Stein Eye Institute, University of California, Los Angeles, Los Angeles, CA 90095-7000, USA.
| | - Alapakkam P Sampath
- Department of Ophthalmology and Jules Stein Eye Institute, University of California, Los Angeles, Los Angeles, CA 90095-7000, USA.
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Scalabrino ML, Thapa M, Wang T, Sampath AP, Chen J, Field GD. Late gene therapy limits the restoration of retinal function in a mouse model of retinitis pigmentosa. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.07.536035. [PMID: 37066264 PMCID: PMC10104154 DOI: 10.1101/2023.04.07.536035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/18/2023]
Abstract
Retinitis pigmentosa is an inherited photoreceptor degeneration that begins with rod loss followed by cone loss and eventual blindness. Gene therapies are being developed, but it is unknown how retinal function depends on the time of intervention. To uncover this dependence, we utilized a mouse model of retinitis pigmentosa capable of artificial genetic rescue. This model enables a benchmark of best-case gene therapy by removing the variables that complicate the ability to answer this vital question. Complete genetic rescue was performed at 25%, 50%, and 70% rod loss (early, mid and late, respectively). Early and mid treatment restored retinal function to near wild-type levels, specifically the sensitivity and signal fidelity of retinal ganglion cells (RGCs), the 'output' neurons of the retina. However, some anatomical defects persisted. Late treatment retinas exhibited continued, albeit slowed, loss of sensitivity and signal fidelity among RGCs, as well as persistent gliosis. We conclude that gene replacement therapies delivered after 50% rod loss are unlikely to restore visual function to normal. This is critical information for administering gene therapies to rescue vision.
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Affiliation(s)
- Miranda L Scalabrino
- Stein Eye Institute, Department of Ophthalmology, University of California, Los Angeles CA
- Department of Neurobiology, Duke University School of Medicine, Durham NC
| | - Mishek Thapa
- Stein Eye Institute, Department of Ophthalmology, University of California, Los Angeles CA
- Department of Neurobiology, Duke University School of Medicine, Durham NC
| | - Tian Wang
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles CA
| | - Alapakkam P Sampath
- Stein Eye Institute, Department of Ophthalmology, University of California, Los Angeles CA
| | - Jeannie Chen
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles CA
| | - Greg D Field
- Stein Eye Institute, Department of Ophthalmology, University of California, Los Angeles CA
- Department of Neurobiology, Duke University School of Medicine, Durham NC
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Scalabrino ML, Field GD. Neuroscience: Visual restoration with optogenetics. Curr Biol 2023; 33:R110-R112. [PMID: 36750022 DOI: 10.1016/j.cub.2022.12.052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Treating photoreceptor degenerative diseases is an exciting application of optogenetic technologies. However, there are significant challenges, such as producing normal visual signaling as the retina rewires in response to photoreceptor death. However, a new study shows remarkable functional stability in retinal circuits that can be engaged by optogenetics following photoreceptor loss.
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Affiliation(s)
- Miranda L Scalabrino
- Stein Eye Institute, Department of Ophthalmology, University of California, Los Angeles, CA 90095, USA
| | - Greg D Field
- Stein Eye Institute, Department of Ophthalmology, University of California, Los Angeles, CA 90095, USA.
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Scalabrino ML, Thapa M, Chew LA, Zhang E, Xu J, Sampath AP, Chen J, Field GD. Robust cone-mediated signaling persists late into rod photoreceptor degeneration. eLife 2022; 11:e80271. [PMID: 36040015 PMCID: PMC9560159 DOI: 10.7554/elife.80271] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Accepted: 08/25/2022] [Indexed: 01/13/2023] Open
Abstract
Rod photoreceptor degeneration causes deterioration in the morphology and physiology of cone photoreceptors along with changes in retinal circuits. These changes could diminish visual signaling at cone-mediated light levels, thereby limiting the efficacy of treatments such as gene therapy for rescuing normal, cone-mediated vision. However, the impact of progressive rod death on cone-mediated signaling remains unclear. To investigate the fidelity of retinal ganglion cell (RGC) signaling throughout disease progression, we used a mouse model of rod degeneration (Cngb1neo/neo). Despite clear deterioration of cone morphology with rod death, cone-mediated signaling among RGCs remained surprisingly robust: spatiotemporal receptive fields changed little and the mutual information between stimuli and spiking responses was relatively constant. This relative stability held until nearly all rods had died and cones had completely lost well-formed outer segments. Interestingly, RGC information rates were higher and more stable for natural movies than checkerboard noise as degeneration progressed. The main change in RGC responses with photoreceptor degeneration was a decrease in response gain. These results suggest that gene therapies for rod degenerative diseases are likely to prolong cone-mediated vision even if there are changes to cone morphology and density.
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Affiliation(s)
- Miranda L Scalabrino
- Department of Neurobiology, Duke University School of MedicineDurhamUnited States
| | - Mishek Thapa
- Department of Neurobiology, Duke University School of MedicineDurhamUnited States
| | - Lindsey A Chew
- Department of Neurobiology, Duke University School of MedicineDurhamUnited States
| | - Esther Zhang
- Department of Neurobiology, Duke University School of MedicineDurhamUnited States
| | - Jason Xu
- Department of Statistical Science, Duke UniversityDurhamUnited States
| | - Alapakkam P Sampath
- Jules Stein Eye Institute, University of California, Los AngelesLos AngelesUnited States
| | - Jeannie Chen
- Zilkha Neurogenetics Institute, Keck School of Medicine, University of Southern CaliforniaLos AngelesUnited States
| | - Greg D Field
- Department of Neurobiology, Duke University School of MedicineDurhamUnited States
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