1
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Vats A, Xi Z, Byrne LC, Chen Y. Retinal Explant Culture from Mouse, Human, and Nonhuman Primates and Its Applications in Vision Research. Methods Mol Biol 2025; 2848:169-186. [PMID: 39240523 DOI: 10.1007/978-1-0716-4087-6_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/07/2024]
Abstract
The retinal explant culture system is a valuable tool for studying the pharmacological, toxicological, and developmental aspects of the retina. It is also used for translational studies such as gene therapy. While no photoreceptor-like cell lines are available for in vitro studies of photoreceptor cell biology, the retinal explant culture maintains the laminated retinal structure ex vivo for as long as a month. Human and nonhuman primate (NHP) postmortem retinal explants cut into small pieces offer the possibility of testing multiple conditions for safety and adeno-associated viral (AAV) vector optimization. In addition, the cone-enriched foveal area can be studied using the retinal explants. Here, we present a detailed working protocol for retinal explant isolation and culture from mouse, human, and NHP for testing drug efficacy and AAV transduction. Future applications of this protocol include combining live imaging and multiwell retinal explant culture for high-throughput drug screening systems in rodent and human retinal explants to identify new drugs against retinal degeneration.
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Affiliation(s)
- Abhishek Vats
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Zhouhuan Xi
- Department of Ophthalmology, Eye Center, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, China
| | - Leah C Byrne
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - Yuanyuan Chen
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, USA.
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA.
- McGowan Institute of Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA.
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2
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Fradot V, Augustin S, Fontaine V, Marazova K, Guillonneau X, Sahel JA, Picaud S. Rodent Models of Retinal Degeneration: From Purified Cells in Culture to Living Animals. Cold Spring Harb Perspect Med 2024; 14:a041311. [PMID: 37848250 PMCID: PMC11444255 DOI: 10.1101/cshperspect.a041311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2023]
Abstract
Rodent models of retinal degeneration are essential for the development of therapeutic strategies. In addition to living animal models, we here also discuss models based on rodent cell cultures, such as purified retinal ganglion cells and retinal explants. These ex vivo models extend the possibilities for investigating pathological mechanisms and assessing the neuroprotective effect of pharmacological agents by eliminating questions on drug pharmacokinetics and bioavailability. The number of living rodent models has greatly increased with the possibilities to achieve transgenic modifications in animals for knocking in and out genes and mutations. The Cre-lox system has further enabled investigators to target specific genes or mutations in specific cells at specific stages. However, chemically or physically induced models can provide alternatives to such targeted gene modifications. The increased diversity of rodent models has widened our possibility to address most ocular pathologies for providing initial proof of concept of innovative therapeutic strategies.
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Affiliation(s)
- Valérie Fradot
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris F-75012, France
| | - Sébastien Augustin
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris F-75012, France
| | - Valérie Fontaine
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris F-75012, France
| | - Katia Marazova
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris F-75012, France
| | - Xavier Guillonneau
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris F-75012, France
| | - José A Sahel
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris F-75012, France
- Department of Ophthalmology, The University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA
| | - Serge Picaud
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris F-75012, France
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3
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Bassetto M, Sen M, Poulhes F, Arango-Gonzalez B, Ueffing M, Zelphati O. Method for siRNA delivery in retina explants. Methods Cell Biol 2023; 176:199-216. [PMID: 37164538 DOI: 10.1016/bs.mcb.2022.12.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Several barriers prevent the delivery of nucleic acids to the retina and limit the application of established technologies, such as RNA interference (RNAi), in the study of retinae biology. Organotypic culture of retinal explants is a convenient method to decrease the complexity of the biological environment surrounding the retina while preserving most of its physiological features. Nevertheless, eliciting significant, non-toxic RNAi in retina explants is not straightforward. Retina explants are mainly constituted by neurons organized in discrete circuits embedded within a complex 3D extracellular matrix. About 70% of these neurons are post-mitotic ciliated cells that respond to light. Unfortunately, like the other cells of the retina, photoreceptors are refractory to transfection, and a toxic delivery of nucleic acid often results in permanent cell loss. RNAi has been applied to retina explants using electroporation, viral, and non-viral vectors but with reproducible, poor gene silencing efficiency. In addition, only a few superficial cells can be transduced/transfected in adult retina explants. Therefore, viruses are often injected into the eye of embryos prior to excision of the retina. However, embryonic explants are not the best model to study most retina diseases since even if they are viable for several weeks, the pathological phenotype often appears later in development. We describe a robust and straightforward method to elicit significant RNAi in adult retina explant using Reverse Magnetofection. This transfection method offers a simple tool for non-toxic gene knockdown of specific genes in adult retina explants by using cationic magnetic nanoparticles (MNPs) to complex and deliver short interfering-RNAs (siRNA) in retina cells under the action of a magnetic field.
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Affiliation(s)
- Marco Bassetto
- OZ Biosciences, Parc Scientifique de Luminy, CEDEX 9, Marseille, France; Gavin Herbert Eye Institute, Center for Translational Vision Research, Department of Physiology & Biophysics, University of California, Irvine, CA, United States
| | - Merve Sen
- Centre of Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | - Florent Poulhes
- OZ Biosciences, Parc Scientifique de Luminy, CEDEX 9, Marseille, France.
| | - Blanca Arango-Gonzalez
- Centre of Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | - Marius Ueffing
- Centre of Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | - Olivier Zelphati
- OZ Biosciences, Parc Scientifique de Luminy, CEDEX 9, Marseille, France
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4
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Wu WH, Tso A, Breazzano MP, Jenny LA, Levi SR, Tsang SH, Quinn PMJ. Culture of Human Retinal Explants for Ex Vivo Assessment of AAV Gene Delivery. Methods Mol Biol 2022; 2560:303-311. [PMID: 36481906 DOI: 10.1007/978-1-0716-2651-1_28] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Due to the clinically established safety and efficacy profile of recombinant adeno-associated viral (rAAV) vectors, they are considered the "go to" vector for retinal gene therapy. Design of a rAAV-mediated gene therapy focuses on cell tropism, high transduction efficiency, and high transgene expression levels to achieve the lowest therapeutic treatment dosage and avoid toxicity. Human retinal explants are a clinically relevant model system for exploring these aspects of rAAV-mediated gene delivery. In this chapter, we describe an ex vivo human retinal explant culture protocol to evaluate transgene expression in order to determine the selectivity and efficacy of rAAV vectors for human retinal gene therapy.
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Affiliation(s)
- Wen-Hsuan Wu
- Edward S. Harkness Eye Institute, Department of Ophthalmology, Columbia University Irving Medical Center/New York-Presbyterian Hospital, New York, NY, USA
| | - Amy Tso
- Edward S. Harkness Eye Institute, Department of Ophthalmology, Columbia University Irving Medical Center/New York-Presbyterian Hospital, New York, NY, USA
| | - Mark P Breazzano
- Edward S. Harkness Eye Institute, Department of Ophthalmology, Columbia University Irving Medical Center/New York-Presbyterian Hospital, New York, NY, USA.,Department of Ophthalmology, New York University School of Medicine, New York University Langone Health, New York, NY, USA.,Manhattan Eye, Ear and Throat Hospital, Lenox Hill Hospital, Northwell Health, New York, NY, USA
| | - Laura A Jenny
- Edward S. Harkness Eye Institute, Department of Ophthalmology, Columbia University Irving Medical Center/New York-Presbyterian Hospital, New York, NY, USA.,Department of Ophthalmology, New York University School of Medicine, New York University Langone Health, New York, NY, USA.,Manhattan Eye, Ear and Throat Hospital, Lenox Hill Hospital, Northwell Health, New York, NY, USA
| | - Sarah R Levi
- Edward S. Harkness Eye Institute, Department of Ophthalmology, Columbia University Irving Medical Center/New York-Presbyterian Hospital, New York, NY, USA.,Department of Ophthalmology, New York University School of Medicine, New York University Langone Health, New York, NY, USA.,Manhattan Eye, Ear and Throat Hospital, Lenox Hill Hospital, Northwell Health, New York, NY, USA
| | - Stephen H Tsang
- Departments of Ophthalmology, Pathology & Cell Biology, Graduate Programs in Nutritional & Metabolic Biology and Neurobiology & Behavior, Columbia Stem Cell Initiative, New York, NY, USA
| | - Peter M J Quinn
- Department of Opthalmology, Columbia University Medical Center, New York, NY, USA.
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5
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Xi Z, Öztürk BE, Johnson ME, Turunç S, Stauffer WR, Byrne LC. Quantitative single-cell transcriptome-based ranking of engineered AAVs in human retinal explants. Mol Ther Methods Clin Dev 2022; 25:476-489. [PMID: 35615708 PMCID: PMC9118357 DOI: 10.1016/j.omtm.2022.04.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 04/26/2022] [Indexed: 11/07/2022]
Abstract
Gene therapy is a rapidly developing field, and adeno-associated viruses (AAVs) are a leading viral-vector candidate for therapeutic gene delivery. Newly engineered AAVs with improved abilities are now entering the clinic. It has proven challenging, however, to predict the translational potential of gene therapies developed in animal models due to cross-species differences. Human retinal explants are the only available model of fully developed human retinal tissue and are thus important for the validation of candidate AAV vectors. In this study, we evaluated 18 wild-type and engineered AAV capsids in human retinal explants using a recently developed single-cell RNA sequencing (RNA-seq) AAV engineering pipeline (scAAVengr). Human retinal explants retained the same major cell types as fresh retina, with similar expression of cell-specific markers except for a photoreceptor population with altered expression of photoreceptor-specific genes. The efficiency and tropism of AAVs in human explants were quantified with single-cell resolution. The top-performing serotypes, K91, K912, and 7m8, were further validated in non-human primate and human retinal explants. Together, this study provides detailed information about the transcriptome profiles of retinal explants and quantifies the infectivity of leading AAV serotypes in human retina, accelerating the translation of retinal gene therapies to the clinic.
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Affiliation(s)
- Zhouhuan Xi
- Department of Ophthalmology, University of Pittsburgh, PA, USA.,Eye Center of Xiangya Hospital, Hunan Key Laboratory of Ophthalmology, Central South University, Changsha, Hunan, China
| | - Bilge E Öztürk
- Department of Ophthalmology, University of Pittsburgh, PA, USA
| | - Molly E Johnson
- Department of Ophthalmology, University of Pittsburgh, PA, USA
| | - Serhan Turunç
- Department of Ophthalmology, University of Pittsburgh, PA, USA
| | | | - Leah C Byrne
- Department of Ophthalmology, University of Pittsburgh, PA, USA.,Department of Neurobiology, University of Pittsburgh, PA, USA.,Department of Bioengineering, University of Pittsburgh, PA, USA
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6
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Bansal A, Shikha S, Zhang Y. Towards translational optogenetics. Nat Biomed Eng 2022; 7:349-369. [PMID: 35027688 DOI: 10.1038/s41551-021-00829-3] [Citation(s) in RCA: 51] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 10/21/2021] [Indexed: 02/07/2023]
Abstract
Optogenetics is widely used to interrogate the neural circuits underlying disease and has most recently been harnessed for therapeutic applications. The optogenetic toolkit consists of light-responsive proteins that modulate specific cellular functions, vectors for the delivery of the transgenes that encode the light-responsive proteins to targeted cellular populations, and devices for the delivery of light of suitable wavelengths at effective fluence rates. A refined toolkit with a focus towards translational uses would include efficient and safer viral and non-viral gene-delivery vectors, increasingly red-shifted photoresponsive proteins, nanomaterials that efficiently transduce near-infrared light deep into tissue, and wireless implantable light-delivery devices that allow for spatiotemporally precise interventions at clinically relevant tissue depths. In this Review, we examine the current optogenetics toolkit and the most notable preclinical and translational uses of optogenetics, and discuss future methodological and translational developments and bottlenecks.
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Affiliation(s)
- Akshaya Bansal
- Department of Biomedical Engineering, Faculty of Engineering, National University of Singapore, Singapore, Singapore
| | - Swati Shikha
- Department of Biomedical Engineering, Faculty of Engineering, National University of Singapore, Singapore, Singapore
| | - Yong Zhang
- Department of Biomedical Engineering, Faculty of Engineering, National University of Singapore, Singapore, Singapore. .,NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore, Singapore. .,NUS Suzhou Research Institute, Suzhou, Jiangsu, P. R. China.
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7
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Botto C, Rucli M, Tekinsoy MD, Pulman J, Sahel JA, Dalkara D. Early and late stage gene therapy interventions for inherited retinal degenerations. Prog Retin Eye Res 2021; 86:100975. [PMID: 34058340 DOI: 10.1016/j.preteyeres.2021.100975] [Citation(s) in RCA: 83] [Impact Index Per Article: 27.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 05/18/2021] [Accepted: 05/21/2021] [Indexed: 12/12/2022]
Abstract
Inherited and age-related retinal degeneration is the hallmark of a large group of heterogeneous diseases and is the main cause of untreatable blindness today. Genetic factors play a major pathogenic role in retinal degenerations for both monogenic diseases (such as retinitis pigmentosa) and complex diseases with established genetic risk factors (such as age-related macular degeneration). Progress in genotyping techniques and back of the eye imaging are completing our understanding of these diseases and their manifestations in patient populations suffering from retinal degenerations. It is clear that whatever the genetic cause, the majority of vision loss in retinal diseases results from the loss of photoreceptor function. The timing and circumstances surrounding the loss of photoreceptor function determine the adequate therapeutic approach to use for each patient. Among such approaches, gene therapy is rapidly becoming a therapeutic reality applicable in the clinic. This massive move from laboratory work towards clinical application has been propelled by the advances in our understanding of disease genetics and mechanisms, gene delivery vectors, gene editing systems, and compensatory strategies for loss of photoreceptor function. Here, we provide an overview of existing modalities of retinal gene therapy and their relevance based on the needs of patient populations suffering from inherited retinal degenerations.
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Affiliation(s)
- Catherine Botto
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012, Paris, France
| | - Marco Rucli
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012, Paris, France
| | - Müge Defne Tekinsoy
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012, Paris, France
| | - Juliette Pulman
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012, Paris, France
| | - José-Alain Sahel
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012, Paris, France; Department of Ophthalmology, The University of Pittsburgh School of Medicine, Pittsburgh, PA, 15213, United States; CHNO des Quinze-Vingts, INSERM-DGOS CIC 1423, F-75012, Paris, France; Fondation Ophtalmologique Rothschild, F-75019, Paris, France
| | - Deniz Dalkara
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012, Paris, France.
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8
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The Rise of Retinal Organoids for Vision Research. Int J Mol Sci 2020; 21:ijms21228484. [PMID: 33187246 PMCID: PMC7697892 DOI: 10.3390/ijms21228484] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 11/03/2020] [Accepted: 11/07/2020] [Indexed: 02/07/2023] Open
Abstract
Retinal degenerative diseases lead to irreversible blindness. Decades of research into the cellular and molecular mechanisms of retinal diseases, using either animal models or human cell-derived 2D systems, facilitated the development of several therapeutic interventions. Recently, human stem cell-derived 3D retinal organoids have been developed. These self-organizing 3D organ systems have shown to recapitulate the in vivo human retinogenesis resulting in morphological and functionally similar retinal cell types in vitro. In less than a decade, retinal organoids have assisted in modeling several retinal diseases that were rather difficult to mimic in rodent models. Retinal organoids are also considered as a photoreceptor source for cell transplantation therapies to counteract blindness. Here, we highlight the development and field’s improvements of retinal organoids and discuss their application aspects as human disease models, pharmaceutical testbeds, and cell sources for transplantations.
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9
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Abstract
Retinal degenerative diseases caused by photoreceptor cell death are major causes of irreversible vision loss. As only primates have a macula, the nonhuman primate (NHP) models have a crucial role not only in revealing biological mechanisms underlying high-acuity vision but also in the development of therapies. Successful translation of basic research findings into clinical trials and, moreover, approval of the first therapies for blinding inherited and age-related retinal dystrophies has been reported in recent years. This article explores the value of the NHP models in understanding human vision and reviews their contribution to the development of innovative therapeutic strategies to save and restore vision.
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10
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Murali A, Ramlogan-Steel CA, Steel JC, Layton CJ. Characterisation and validation of the 8-fold quadrant dissected human retinal explant culture model for pre-clinical toxicology investigation. Toxicol In Vitro 2019; 63:104716. [PMID: 31706033 DOI: 10.1016/j.tiv.2019.104716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 10/13/2019] [Accepted: 11/04/2019] [Indexed: 11/30/2022]
Abstract
One of the major challenges in studying ocular toxicology is a lack of clinically-relevant retinal experimental models. In this study we describe the use of an in vitro human retinal explant strategy to generate a reproducible experimental model with utility in neuro-toxicity retinal studies. A retinal dissection strategy, referred to as the 8 fold quadrant dissection, was developed by dissecting human donor retinas into 4 fragments through the fovea in order to obtain 8 experimentally reproducible retinal explants from a single donor. This quadrant dissection gave rise to equivalent proportions of CD73+ photoreceptors and CD90+ ganglion cells in 8 fragments from a single donor and this remained stable for up to 3 days in culture. Major retinal cell types continued to be observed after 8 weeks in culture, despite breakdown of the retinal layers, suggesting the potential to use this model in long-term studies where observation of individual cell types is possible. The utility of this system was examined in a proof of principle neuro-toxicology study. We showed reproducible induction of toxicity in photoreceptors and retinal ganglion cells by glutamate, cobalt chloride and hydrogen peroxide insults, and observed the therapeutic positive effects of the administration of memantine, formononetin and trolox. The quadrant dissected human retinal explants have the potential to be used in toxicology studies in human ocular diseases.
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Affiliation(s)
- Aparna Murali
- LVF Ophthalmology Research Centre, Translational Research Institute, Woolloongabba, QLD, Australia; Greenslopes Clinical School, Faculty of Medicine, University of Queensland, Greenslopes Hospital, Australia
| | - Charmaine A Ramlogan-Steel
- LVF Ophthalmology Research Centre, Translational Research Institute, Woolloongabba, QLD, Australia; Central Queensland University, School of Health, Medical and Applied Science, Rockhampton, QLD, Australia
| | - Jason C Steel
- Central Queensland University, School of Health, Medical and Applied Science, Rockhampton, QLD, Australia.
| | - Christopher J Layton
- LVF Ophthalmology Research Centre, Translational Research Institute, Woolloongabba, QLD, Australia; Greenslopes Clinical School, Faculty of Medicine, University of Queensland, Greenslopes Hospital, Australia.
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11
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Devoldere J, Peynshaert K, Dewitte H, Vanhove C, De Groef L, Moons L, Özcan SY, Dalkara D, De Smedt SC, Remaut K. Non-viral delivery of chemically modified mRNA to the retina: Subretinal versus intravitreal administration. J Control Release 2019; 307:315-330. [PMID: 31265881 DOI: 10.1016/j.jconrel.2019.06.042] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 05/20/2019] [Accepted: 06/29/2019] [Indexed: 12/20/2022]
Abstract
mRNA therapeutics have recently experienced a new wave of interest, mainly due to the discovery that chemical modifications to mRNA's molecular structure could drastically reduce its inherent immunogenicity and perceived instability. On this basis, we aimed to explore the potential of chemically stabilized mRNA for ocular applications. More specifically, we investigated the behavior of mRNA-loaded lipid-based carriers in human retinal cells (in vitro), in bovine retinal explants (ex vivo) and in mouse retinas (in vivo). We demonstrate a clear superiority of mRNA over pDNA to induce protein expression in different retinal cell types, which was further enhanced by chemical modification of the mRNA, providing up to ~1800-fold higher reporter gene expression compared to pDNA. Moreover, transgene expression could be detected for at least 20 days after a single administration of chemically modified mRNA in vitro. We furthermore determined the localization and extent of mRNA expression depending on the administration route. After subretinal (SR) administration, mRNA expression was observed in vivo and ex vivo. By contrast, intravitreal (IVT) administration resulted in limited expression in vivo. Using ex vivo bovine explants with an intact vitreoretinal (VR) interface we could attribute this to the inner limiting membrane (ILM), which presents a large barrier for non-viral delivery of mRNA, trapping mRNA complexes at the vitreal side. When the vitreous was removed, which compromises the ILM, mRNA expression was apparent and seemed to colocalize with Müller cells or photoreceptors after respectively IVT or SR administration. Taken together, this study represents a first step towards mRNA-mediated therapy for retinal diseases.
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Affiliation(s)
- Joke Devoldere
- Ghent Research Group on Nanomedicines, Laboratory of General Biochemistry and Physical Pharmacy, Ghent University, Ottergemsesteenweg 460, 9000 Ghent, Belgium
| | - Karen Peynshaert
- Ghent Research Group on Nanomedicines, Laboratory of General Biochemistry and Physical Pharmacy, Ghent University, Ottergemsesteenweg 460, 9000 Ghent, Belgium
| | - Heleen Dewitte
- Ghent Research Group on Nanomedicines, Laboratory of General Biochemistry and Physical Pharmacy, Ghent University, Ottergemsesteenweg 460, 9000 Ghent, Belgium; Laboratory for Molecular and Cellular Therapy, Department of Biomedical Sciences, Medical School of the Vrije Universiteit Brussel (VUB), Laarbeeklaan 103, 1050 Jette, Belgium; Cancer Research Institute Ghent (CRIG), Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium
| | - Christian Vanhove
- Department of Respiratory Medicine, Ghent University, 9000 Ghent, Belgium
| | - Lies De Groef
- Neural Circuit Development and Regeneration Research Group, Animal Physiology and Neurobiology Section, Department of Biology, KU Leuven, Leuven, Belgium
| | - Lieve Moons
- Neural Circuit Development and Regeneration Research Group, Animal Physiology and Neurobiology Section, Department of Biology, KU Leuven, Leuven, Belgium
| | - Sinem Yilmaz Özcan
- Neurological Sciences and Psychiatry Institute; Hacettepe University, Ankara, Turkey
| | - Deniz Dalkara
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 17 rue Moreau, F-75012 Paris, France
| | - Stefaan C De Smedt
- Ghent Research Group on Nanomedicines, Laboratory of General Biochemistry and Physical Pharmacy, Ghent University, Ottergemsesteenweg 460, 9000 Ghent, Belgium; Cancer Research Institute Ghent (CRIG), Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium
| | - Katrien Remaut
- Ghent Research Group on Nanomedicines, Laboratory of General Biochemistry and Physical Pharmacy, Ghent University, Ottergemsesteenweg 460, 9000 Ghent, Belgium; Cancer Research Institute Ghent (CRIG), Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium.
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12
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Masri RA, Lee SCS, Madigan MC, Grünert U. Particle-Mediated Gene Transfection and Organotypic Culture of Postmortem Human Retina. Transl Vis Sci Technol 2019; 8:7. [PMID: 30941264 PMCID: PMC6438245 DOI: 10.1167/tvst.8.2.7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 01/07/2019] [Indexed: 12/25/2022] Open
Abstract
Purpose Particle-mediated gene transfer has been used in animal models to study the morphology and connectivity of retinal ganglion cells. The aim of the present study was to apply this method to transfect ganglion cells in postmortem human retina. Methods Postmortem human eyes from male and female donors aged 40 to 76 years old were obtained within 15 hours after death. In addition, two marmoset retinas were obtained immediately after death. Ganglion cells were transfected with an expression plasmid for the postsynaptic density 95 protein conjugated to green or yellow fluorescent protein. Retinas were cultured for 3 days, fixed and then processed with immunohistochemical markers to reveal their stratification in the inner plexiform layer. Results The retinas maintained their morphology and immunohistochemical properties for at least 3 days in culture. Bipolar and ganglion cell morphology was comparable to that observed in noncultured tissue. The quality of transfected cells in human retina was similar to that in freshly enucleated marmoset eyes. Based on dendritic field size and stratification, at least 11 morphological types of retinal ganglion cell were distinguished. Conclusions Particle-mediated gene transfer allows efficient targeting of retinal ganglion cells in cultured postmortem human retina. Translational Relevance The translational value of this methodology lies in the provision of an in vitro platform to study structural and connectivity changes in human eye diseases that affect the integrity and organization of cells in the retina.
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Affiliation(s)
- Rania A Masri
- The University of Sydney, Faculty of Medicine and Health, Save Sight Institute and Discipline of Ophthalmology, Sydney, Australia.,Australian Research Council Centre of Excellence for Integrative Brain Function, Sydney Node, The University of Sydney, Sydney, Australia
| | - Sammy C S Lee
- The University of Sydney, Faculty of Medicine and Health, Save Sight Institute and Discipline of Ophthalmology, Sydney, Australia.,Australian Research Council Centre of Excellence for Integrative Brain Function, Sydney Node, The University of Sydney, Sydney, Australia
| | - Michele C Madigan
- The University of Sydney, Faculty of Medicine and Health, Save Sight Institute and Discipline of Ophthalmology, Sydney, Australia.,School of Optometry and Vision Science, University of New South Wales, Sydney, Australia
| | - Ulrike Grünert
- The University of Sydney, Faculty of Medicine and Health, Save Sight Institute and Discipline of Ophthalmology, Sydney, Australia.,Australian Research Council Centre of Excellence for Integrative Brain Function, Sydney Node, The University of Sydney, Sydney, Australia
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13
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Murali A, Ramlogan-Steel CA, Andrzejewski S, Steel JC, Layton CJ. Retinal explant culture: A platform to investigate human neuro-retina. Clin Exp Ophthalmol 2018; 47:274-285. [PMID: 30378239 DOI: 10.1111/ceo.13434] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 10/01/2018] [Accepted: 10/22/2018] [Indexed: 01/09/2023]
Abstract
The retina is the tissue responsible for light detection, in which retinal neurons convert light energy into electrical signals to be transported towards the visual cortex. Damage of retinal neurons leads to neuronal cell death and retinal pathologies, compromising visual acuity and eventually leading to irreversible blindness. Models of retinal neurodegeneration include 2D systems like cell lines, disassociated cultures and co-cultures, and 3D models like organoids, organotypic retinal cultures and animal models. Of these, ex vivo human retinal cultures are arguably the most suitable models for translational research as they retain complex inter-cellular interactions of the retina and precisely mimic in-situ responses. In this review, we summarize the distinguishing features of the human retina which are important to preserve in experimental culture, the historical development of human retinal culture systems, the factors affecting ex vivo human retinal culture and the applications and challenges associated with current methods of human retinal explant culture.
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Affiliation(s)
- Aparna Murali
- LVF Ophthalmology Research Centre, Translational Research Institute, Woolloongabba, Queensland, Australia.,Faculty of Medicine, The University of Queensland, Herston, Queensland, Australia
| | - Charmaine A Ramlogan-Steel
- Faculty of Medicine, The University of Queensland, Herston, Queensland, Australia.,School of Health, Medical and Applied Sciences, CQUniversity, North Rockhampton, Queensland, Australia
| | - Slawomir Andrzejewski
- LVF Ophthalmology Research Centre, Translational Research Institute, Woolloongabba, Queensland, Australia.,Faculty of Medicine, The University of Queensland, Herston, Queensland, Australia
| | - Jason C Steel
- School of Health, Medical and Applied Sciences, CQUniversity, North Rockhampton, Queensland, Australia
| | - Christopher J Layton
- LVF Ophthalmology Research Centre, Translational Research Institute, Woolloongabba, Queensland, Australia.,Faculty of Medicine, The University of Queensland, Greenslopes Hospital, Brisbane, Queensland, Australia
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14
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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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15
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Molecular Fingerprinting of On-Off Direction-Selective Retinal Ganglion Cells Across Species and Relevance to Primate Visual Circuits. J Neurosci 2018; 39:78-95. [PMID: 30377226 DOI: 10.1523/jneurosci.1784-18.2018] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Revised: 10/08/2018] [Accepted: 10/23/2018] [Indexed: 12/27/2022] Open
Abstract
The ability to detect moving objects is an ethologically salient function. Direction-selective neurons have been identified in the retina, thalamus, and cortex of many species, but their homology has remained unclear. For instance, it is unknown whether direction-selective retinal ganglion cells (DSGCs) exist in primates and, if so, whether they are the equivalent to mouse and rabbit DSGCs. Here, we used a molecular/circuit approach in both sexes to address these issues. In mice, we identify the transcription factor Satb2 (special AT-rich sequence-binding protein 2) as a selective marker for three RGC types: On-Off DSGCs encoding motion in either the anterior or posterior direction, a newly identified type of Off-DSGC, and an Off-sustained RGC type. In rabbits, we find that expression of Satb2 is conserved in On-Off DSGCs; however, it has evolved to include On-Off DSGCs encoding upward and downward motion in addition to anterior and posterior motion. Next, we show that macaque RGCs express Satb2 most likely in a single type. We used rabies virus-based circuit-mapping tools to reveal the identity of macaque Satb2-RGCs and discovered that their dendritic arbors are relatively large and monostratified. Together, these data indicate Satb2-expressing On-Off DSGCs are likely not present in the primate retina. Moreover, if DSGCs are present in the primate retina, it is unlikely that they express Satb2.SIGNIFICANCE STATEMENT The ability to detect object motion is a fundamental feature of almost all visual systems. Here, we identify a novel marker for retinal ganglion cells encoding directional motion that is evolutionarily conserved in mice and rabbits, but not in primates. We show in macaque monkeys that retinal ganglion cells (RGCs) that express this marker comprise a single type and are morphologically distinct from mouse and rabbit direction-selective RGCs. Our findings indicate that On-Off direction-selective retinal neurons may have evolutionarily diverged in primates and more generally provide novel insight into the identity and organization of primate parallel visual pathways.
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16
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Abstract
Restoring vision to the blind by retinal repair has been a dream of medicine for centuries, and the first successful procedures have recently been performed. Although we are still far from the restoration of high-resolution vision, step-by-step developments are overcoming crucial bottlenecks in therapy development and have enabled the restoration of some visual function in patients with specific blindness-causing diseases. Here, we discuss the current state of vision restoration and the problems related to retinal repair. We describe new model systems and translational technologies, as well as the clinical conditions in which new methods may help to combat blindness.
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17
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Peynshaert K, Devoldere J, De Smedt SC, Remaut K. In vitro and ex vivo models to study drug delivery barriers in the posterior segment of the eye. Adv Drug Deliv Rev 2018; 126:44-57. [PMID: 28939376 DOI: 10.1016/j.addr.2017.09.007] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 07/18/2017] [Accepted: 09/08/2017] [Indexed: 12/18/2022]
Abstract
Many ocular disorders leading to blindness could benefit from efficient delivery of therapeutics to the retina. However, despite extensive research into drug delivery vehicles and administration techniques, efficacy remains limited because of the many static and dynamic barriers present in the eye. Comprehension of the various barriers and especially how to overcome them can improve our ability to estimate the potential of existent drug delivery vectors and support the design of new ones. To this end, this review gives an overview of the most important ocular barriers for each administration route to the back of the eye. For each barrier, its biological composition and its role as an obstacle towards macromolecules, nanoparticles and viral vectors will be discussed; special attention will be paid to the influence of size, charge and lipophilicity of drug(s) (carrier) on their ability to overcome each barrier. Finally, the most significant available in vitro and ex vivo methods and models to test the potential of a therapeutic to cross each barrier are listed.
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18
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Khabou H, Garita-Hernandez M, Chaffiol A, Reichman S, Jaillard C, Brazhnikova E, Bertin S, Forster V, Desrosiers M, Winckler C, Goureau O, Picaud S, Duebel J, Sahel JA, Dalkara D. Noninvasive gene delivery to foveal cones for vision restoration. JCI Insight 2018; 3:96029. [PMID: 29367457 DOI: 10.1172/jci.insight.96029] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 12/12/2017] [Indexed: 01/02/2023] Open
Abstract
Intraocular injection of adeno-associated viral (AAV) vectors has been an evident route for delivering gene drugs into the retina. However, gaps in our understanding of AAV transduction patterns within the anatomically unique environments of the subretinal and intravitreal space of the primate eye impeded the establishment of noninvasive and efficient gene delivery to foveal cones in the clinic. Here, we establish new vector-promoter combinations to overcome the limitations associated with AAV-mediated cone transduction in the fovea with supporting studies in mouse models, human induced pluripotent stem cell-derived organoids, postmortem human retinal explants, and living macaques. We show that an AAV9 variant provides efficient foveal cone transduction when injected into the subretinal space several millimeters away from the fovea, without detaching this delicate region. An engineered AAV2 variant provides gene delivery to foveal cones with a well-tolerated dose administered intravitreally. Both delivery modalities rely on a cone-specific promoter and result in high-level transgene expression compatible with optogenetic vision restoration. The model systems described here provide insight into the behavior of AAV vectors across species to obtain safety and efficacy needed for gene therapy in neurodegenerative disorders.
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Affiliation(s)
- Hanen Khabou
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision, Paris, France
| | | | - Antoine Chaffiol
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Sacha Reichman
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Céline Jaillard
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Elena Brazhnikova
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Stéphane Bertin
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision, Paris, France.,CHNO des Quinze-Vingts, DHU Sight Restore, INSERM-DGOS CIC 1423, Paris, France
| | - Valérie Forster
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Mélissa Desrosiers
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Céline Winckler
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Olivier Goureau
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Serge Picaud
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Jens Duebel
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision, Paris, France
| | - José-Alain Sahel
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision, Paris, France.,CHNO des Quinze-Vingts, DHU Sight Restore, INSERM-DGOS CIC 1423, Paris, France.,Fondation Ophtalmologique Rothschild, Paris, France.,Department of Ophthalmology, The University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Deniz Dalkara
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision, Paris, France
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19
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Peynshaert K, Devoldere J, Forster V, Picaud S, Vanhove C, De Smedt SC, Remaut K. Toward smart design of retinal drug carriers: a novel bovine retinal explant model to study the barrier role of the vitreoretinal interface. Drug Deliv 2017; 24:1384-1394. [PMID: 28925755 PMCID: PMC8241179 DOI: 10.1080/10717544.2017.1375578] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Accepted: 08/31/2017] [Indexed: 12/15/2022] Open
Abstract
Retinal gene delivery via intravitreal injection is hampered by various physiological barriers present in the eye of which the vitreoretinal (VR) interface represents the most serious hurdle. In this study, we present a retinal explant model especially designed to study the role of this interface as a barrier for the penetration of vectors into the retina. In contrast to all existing explant models, the developed model is bovine-derived and more importantly, keeps the vitreous attached to the retina at all times to guarantee an intact VR interface. After ex vivo intravitreal injection into the living retinal explant, the route of fluorescent carriers across the VR interface can be tracked. By applying two different imaging methods on this model, we discovered that the transfer through the VR barrier is size-dependent since 40 nm polystyrene particles are more easily taken up in the retina than 100 and 200 nm sized particles. In addition, we found that removing the vitreous, as commonly done for culture of conventional explants, leads to an overestimation of particle uptake, and conclude that the ultimate barrier to overcome for retinal uptake is undoubtedly the inner limiting membrane. Damaging this matrix resulted in a massive increase in particle transfer into the retina. In conclusion, we have developed a highly relevant ex vivo model that maximally mimics the human in vivo physiology which can be applied as a representative test set-up to assess the potential of promising drug delivery carriers to cross the VR interface.
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Affiliation(s)
- Karen Peynshaert
- Lab of General Biochemistry and Physical Pharmacy, Faculty of Pharmaceutical Sciences, Ghent University, Ghent, Belgium
- Ghent Research Group on Nanomedicines, Ghent University, Ghent, Belgium
| | - Joke Devoldere
- Lab of General Biochemistry and Physical Pharmacy, Faculty of Pharmaceutical Sciences, Ghent University, Ghent, Belgium
- Ghent Research Group on Nanomedicines, Ghent University, Ghent, Belgium
| | - Valérie Forster
- Institut de la Vision, INSERM, Université Paris 6, Paris, France
| | - Serge Picaud
- Institut de la Vision, INSERM, Université Paris 6, Paris, France
| | - Christian Vanhove
- Department of Respiratory Medicine, Ghent University, Ghent, Belgium
| | - Stefaan C. De Smedt
- Lab of General Biochemistry and Physical Pharmacy, Faculty of Pharmaceutical Sciences, Ghent University, Ghent, Belgium
- Ghent Research Group on Nanomedicines, Ghent University, Ghent, Belgium
| | - Katrien Remaut
- Lab of General Biochemistry and Physical Pharmacy, Faculty of Pharmaceutical Sciences, Ghent University, Ghent, Belgium
- Ghent Research Group on Nanomedicines, Ghent University, Ghent, Belgium
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20
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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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21
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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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22
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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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23
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In vivo genome editing as a potential treatment strategy for inherited retinal dystrophies. Prog Retin Eye Res 2016; 56:1-18. [PMID: 27623223 DOI: 10.1016/j.preteyeres.2016.09.001] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 09/06/2016] [Accepted: 09/08/2016] [Indexed: 12/20/2022]
Abstract
In vivo genome editing represents an emerging field in the treatment of monogenic disorders, as it may constitute a solution to the current hurdles in classic gene addition therapy, which are the low levels and limited duration of transgene expression. Following the introduction of a double strand break (DSB) at the mutational site by highly specific endonucleases, such as TALENs (transcription activator like effector nucleases) or RNA based nucleases (clustered regulatory interspaced short palindromic repeats - CRISPR-Cas), the cell's own DNA repair machinery restores integrity to the DNA strand and corrects the mutant sequence, thus allowing the cell to produce protein levels as needed. The DNA repair happens either through the error prone non-homologous end-joining (NHEJ) pathway or with high fidelity through homology directed repair (HDR) in the presence of a DNA donor template. A third pathway called microhomology mediated endjoining (MMEJ) has been recently discovered. In this review, the authors focus on the different DNA repair mechanisms, the current state of the art tools for genome editing and the particularities of the retina and photoreceptors with regard to in vivo therapeutic approaches. Finally, current attempts in the field of retinal in vivo genome editing are discussed and future directions of research identified.
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Cronin T, Vandenberghe LH, Hantz P, Juttner J, Reimann A, Kacsó AE, Huckfeldt RM, Busskamp V, Kohler H, Lagali PS, Roska B, Bennett J. Efficient transduction and optogenetic stimulation of retinal bipolar cells by a synthetic adeno-associated virus capsid and promoter. EMBO Mol Med 2015; 6:1175-90. [PMID: 25092770 PMCID: PMC4197864 DOI: 10.15252/emmm.201404077] [Citation(s) in RCA: 124] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In this report, we describe the development of a modified adeno-associated virus (AAV) capsid and promoter for transduction of retinal ON-bipolar cells. The bipolar cells, which are post-synaptic to the photoreceptors, are important retinal targets for both basic and preclinical research. In particular, a therapeutic strategy under investigation for advanced forms of blindness involves using optogenetic molecules to render ON-bipolar cells light-sensitive. Currently, delivery of adequate levels of gene expression is a limiting step for this approach. The synthetic AAV capsid and promoter described here achieves high level of optogenetic transgene expression in ON-bipolar cells. This evokes high-frequency (∼100 Hz) spiking responses in ganglion cells of previously blind, rd1, mice. Our vector is a promising vehicle for further development toward potential clinical use.
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Affiliation(s)
- Therese Cronin
- Center for Advanced Retinal and Ophthalmic Therapeutics, F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, USA Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Luk H Vandenberghe
- Center for Advanced Retinal and Ophthalmic Therapeutics, F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, USA Schepens Eye Research Institute, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA, USA
| | - Péter Hantz
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Josephine Juttner
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Andreas Reimann
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | | | - Rachel M Huckfeldt
- Center for Advanced Retinal and Ophthalmic Therapeutics, F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, USA
| | - Volker Busskamp
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland Genetics Department, Harvard Medical School, Boston, MA, USA
| | - Hubertus Kohler
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Pamela S Lagali
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - Botond Roska
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Jean Bennett
- Center for Advanced Retinal and Ophthalmic Therapeutics, F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, USA
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Abstract
PURPOSE OF REVIEW In this review, we will discuss the recent developments in optogenetics and their potential applications in ophthalmology to restore vision in retinal degenerative diseases. RECENT FINDINGS In recent years, we have seen major advances in the field of optogenetics, providing us with novel opsins for potential applications in the retina. Microbial opsins with improved light sensitivity and red-shifted action spectra allow optogenetic stimulation at light levels well below the safety threshold in the human eye. In parallel, remarkable success in the development of highly efficient viral vectors for ocular gene therapy led to new strategies of using these novel optogenetic tools for vision restoration. SUMMARY These recent findings show that novel optogenetic tools and viral vectors for ocular gene delivery are now available providing many opportunities to develop potential optogenetic strategies for vision restoration.
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Affiliation(s)
- Jens Duebel
- Institut de la Vision
Université Pierre et Marie Curie - Paris 6 - UM80Institut National de la Santé et de la Recherche Médicale - U968Centre National de la Recherche Scientifique - UMR721017 Rue Moreau, 75012 Paris
| | - Katia Marazova
- Institut de la Vision
Université Pierre et Marie Curie - Paris 6 - UM80Institut National de la Santé et de la Recherche Médicale - U968Centre National de la Recherche Scientifique - UMR721017 Rue Moreau, 75012 Paris
| | - José-Alain Sahel
- Institut de la Vision
Université Pierre et Marie Curie - Paris 6 - UM80Institut National de la Santé et de la Recherche Médicale - U968Centre National de la Recherche Scientifique - UMR721017 Rue Moreau, 75012 Paris
- Fondation Ophtalmologique Rothschild
75019 Paris
- Centre Hospitalier National d’Ophtalmologie des Quinze-Vingts
INSERM-DHOS CIC 1423 -
- Institute of Ophthalmology [London]
University College of London [London] - London EC1V 9EL
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Chapter 3 - Restoring Vision to the Blind: Gene Therapy for Vision Loss. Transl Vis Sci Technol 2014; 3:5. [PMID: 25653889 PMCID: PMC4314998 DOI: 10.1167/tvst.3.7.5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 10/27/2014] [Indexed: 01/14/2023] Open
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The retinal phenotype of Usher syndrome: pathophysiological insights from animal models. C R Biol 2014; 337:167-77. [PMID: 24702843 DOI: 10.1016/j.crvi.2013.12.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Accepted: 12/03/2013] [Indexed: 01/26/2023]
Abstract
The Usher syndrome (USH) is the most prevalent cause of inherited deaf-blindness. Three clinical subtypes, USH1-3, have been defined, and ten USH genes identified. The hearing impairment due to USH gene defects has been shown to result from improper organisation of the hair bundle, the sound receptive structure of sensory hair cells. In contrast, the cellular basis of the visual defect is less well understood as this phenotype is absent in almost all the USH mouse models that faithfully mimic the human hearing impairment. Structural and molecular interspecies discrepancies regarding photoreceptor calyceal processes and the association with the distribution of USH1 proteins have recently been unravelled, and have led to the conclusion that a defect in the USH1 protein complex-mediated connection between the photoreceptor outer segment and the surrounding calyceal processes (in both rods and cones), and the inner segment (in rods only), probably causes the USH1 retinal dystrophy in humans.
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Functional rescue of cone photoreceptors in retinitis pigmentosa. Graefes Arch Clin Exp Ophthalmol 2013; 251:1669-77. [PMID: 23575948 DOI: 10.1007/s00417-013-2314-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
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Roska B, Busskamp V, Sahel JA, Picaud S. [Retinitis pigmentosa: eye sight restoration by optogenetic therapy]. Biol Aujourdhui 2013; 207:109-121. [PMID: 24103341 DOI: 10.1051/jbio/2013011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Indexed: 06/02/2023]
Abstract
Retinitis pigmentosa (RP) is a hereditary retinal disease leading to blindness, which affects two million people worldwide. Restoring vision in these blind patients was proposed by gene delivery of microbial light-activated ionic channels or pumps "optogenetic proteins" to transform surviving cells into artificial photoreceptors. This therapeutic strategy was validated in blind animal models of RP by recording at the level of the retina and cortex and by behavioural tests. The translational potentials of these optogenetic approaches have been evaluated using in vitro studies on post-mortem human retinal tissues. Here, we review these recent results and discuss the potential clinical applications of the optogenetic therapy for RP patients.
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Affiliation(s)
- Botond Roska
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66F, 4058 Basel, Switzerland
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Miller JW. Age-related macular degeneration revisited--piecing the puzzle: the LXIX Edward Jackson memorial lecture. Am J Ophthalmol 2013; 155:1-35.e13. [PMID: 23245386 DOI: 10.1016/j.ajo.2012.10.018] [Citation(s) in RCA: 182] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Revised: 10/19/2012] [Accepted: 10/23/2012] [Indexed: 12/11/2022]
Abstract
PURPOSE To present the current understanding of age-related macular degeneration (AMD) pathogenesis, based on clinical evidence, epidemiologic data, histopathologic examination, and genetic data; to provide an update on current and emerging therapies; and to propose an integrated model of the pathogenesis of AMD. DESIGN Review of published clinical and experimental studies. METHODS Analysis and synthesis of clinical and experimental data. RESULTS We are closer to a complete understanding of the pathogenesis of AMD, having progressed from clinical observations to epidemiologic observations and clinical pathologic correlation. More recently, modern genetic and genomic studies have facilitated the exploration of molecular pathways. It seems that AMD is a complex disease that results from the interaction of genetic susceptibility with aging and environmental factors. Disease progression also seems to be driven by a combination of genetic and environmental factors. CONCLUSIONS Therapies based on pathophysiologic features have changed the paradigm for treating neovascular AMD. With improved understanding of the underlying genetic susceptibility, we can identify targets to halt early disease and to prevent progression and vision loss.
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Time course modifications in organotypic culture of human neuroretina. Exp Eye Res 2012; 104:26-38. [PMID: 23022403 DOI: 10.1016/j.exer.2012.08.012] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Revised: 08/29/2012] [Accepted: 08/31/2012] [Indexed: 02/01/2023]
Abstract
The purpose of this study was to characterize organ culture of human neuroretina and to establish survival and early degeneration patterns of neural and glial cells. Sixteen neuroretina explants were prepared from 2 postmortem eyes of 2 individuals. Four explants were used as fresh retina controls, and 12 were evaluated at 3, 6, and 9 days of culture. Neuroretina explants (5 × 5 mm) were cultured in Transwell(®) dishes with the photoreceptor layer facing the supporting membrane. Culture medium (Neurobasal A-based) was maintained in contact with the membrane beneath the explant. Cryostat and ultrathin sections were prepared for immunohistochemistry and electron microscopy. Neuroretinal modifications were evaluated after toluidine blue staining and after immunostaining for neuronal and glial cell markers. Ultrastructural changes were analyzed by electron microscopy. From 0 to 9 days in culture, there was progressive retinal degeneration, including early pyknosis of photoreceptor nuclei, cellular vacuolization in the ganglion cell layer, decrease of both plexiform layer thicknesses, disruption and truncation of photoreceptor outer segments (OS), and marked reduction in the number of nuclei at both nuclear layers where the cells were less densely packed. At 3 days there was swelling of cone OS with impairment of pedicles, loss of axons and dendrites of horizontal and rod bipolar cells that stained for calbindin (CB) and protein kinase C (PKC-α), respectively. After 9 days, horizontal cells were pyknotic and without terminal tips. There were similar degenerative processes in the outer plexiform layer for rod bipolar cells and loss of axon terminal lateral varicosities in the inner plexiform layer. Glial fibrillary acidic protein (GFAP) staining did not reveal a dramatic increase of gliosis in Müller cells. However, some Müller cells were CB immunoreactive at 6 days of culture. Over 9 days of culture, human neuroretina explants underwent morphological changes in photoreceptors, particularly the OS and axon terminals, and in postsynaptic horizontal and bipolar cells. These early changes, not previously described in cultured human samples, reproduce some celullar modifications after retinal damage. Thus, this model may be suitable to evaluate therapeutic agents during retinal degeneration processes.
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Theogarajan L. Strategies for restoring vision to the blind: current and emerging technologies. Neurosci Lett 2012; 519:129-33. [DOI: 10.1016/j.neulet.2012.02.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Accepted: 02/01/2012] [Indexed: 12/31/2022]
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Hufnagel RB, Ahmed ZM, Corrêa ZM, Sisk RA. Gene therapy for Leber congenital amaurosis: advances and future directions. Graefes Arch Clin Exp Ophthalmol 2012; 250:1117-28. [PMID: 22644094 DOI: 10.1007/s00417-012-2028-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Revised: 03/25/2012] [Accepted: 04/03/2012] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND Leber congenital amaurosis (LCA) is a congenital retinal dystrophy that results in significant and often severe vision loss at an early age. Comprehensive analysis of the genetic mutations and phenotypic correlations in LCA patients has allowed for significant improvements in understanding molecular pathways of photoreceptor degeneration and dysfunction. The purpose of this article is to review the literature on the subject of retinal gene therapy for LCA, including historical descriptions, preclinical animal studies, and human clinical trials. METHODS A literature search of peer-reviewed and indexed publications from 1996-2011 using the PubMed search engine was performed. Key terms included "Leber congenital amaurosis", LCA, RPE65, "cone-rod dystrophy", "gene therapy", and "human trials" in various combinations. Seminal articles prior to 1996 were selected from primary sources and reviews from the initial search. Articles were chosen based on pertinence to clinical, genetic, and therapeutic topics reviewed in this manuscript. Fundus photographs from LCA patients were obtained retrospectively from the clinical practice of one of the authors (R.A.S). RESULTS Herein, we reviewed the literature on LCA as a genetic disease, the results of human gene therapy trials to date, and possible future directions towards treating inherited retinal diseases at the genetic level. Original descriptions of LCA by Theodor Leber and subsequent research demonstrate the severity of this disease with early-onset blindness. Discoveries of the causative heritable mutations revealed genes and protein products involved in photoreceptor development and visual transduction. Animal models have provided a means to test novel therapeutic strategies, namely gene therapy. Stemming from these experiments, three independent clinical trials tested the safety of subretinal delivery of viral gene therapy to patients with mutations in the RPE65 gene. More recently, efficacy studies have been conducted with encouraging results. CONCLUSIONS Initial safety studies indicated promising results of subretinal delivery of viral vector with subclinical immunologic or surgical sequelae. Overall, these initial studies demonstrate that viral vector gene therapy results are very promising, safe, and effective. Future studies measuring potential improvement in photoreceptor function may rely on recent advances in retinal imaging and electrophysiologic testing.
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Affiliation(s)
- Robert B Hufnagel
- Department of Pediatrics, Division of Pediatric Ophthalmology, University of Cincinnati and Cincinnati Children's Hospital, College of Medicine, 3333 Burnet Ave, ML 7003, Cincinnati, OH 45229, USA.
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Vandenberghe LH, Auricchio A. Novel adeno-associated viral vectors for retinal gene therapy. Gene Ther 2011; 19:162-8. [PMID: 21993172 DOI: 10.1038/gt.2011.151] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Vectors derived from adeno-associated virus (AAV) are currently the most promising vehicles for therapeutic gene delivery to the retina. Recently, subretinal administration of AAV2 has been demonstrated to be safe and effective in patients with a rare form of inherited childhood blindness, suggesting that AAV-mediated retinal gene therapy may be successfully extended to other blinding conditions. This is further supported by the great versatility of AAV as a vector platform as there are a large number of AAV variants and many of these have unique transduction characteristics useful for targeting different cell types in the retina including glia, epithelium and many types of neurons. Naturally occurring, rationally designed or in vitro evolved AAV vectors are currently being utilized to transduce several different cell types in the retina and to treat a variety of animal models of retinal disease. The continuous and creative development of AAV vectors provides opportunities to overcome existing challenges in retinal gene therapy such as efficient transfer of genes exceeding AAV's cargo capacity, or the targeting of specific cells within the retina or transduction of photoreceptors following routinely used intravitreal injections. Such developments should ultimately advance the treatment of a wide range of blinding retinal conditions.
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Affiliation(s)
- L H Vandenberghe
- Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, USA.
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