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Mizobuchi K, Hayashi T, Tanaka K, Kuniyoshi K, Murakami Y, Nakamura N, Torii K, Mizota A, Sakai D, Maeda A, Kominami T, Ueno S, Kusaka S, Nishiguchi KM, Ikeda Y, Kondo M, Tsunoda K, Hotta Y, Nakano T. Genetic and Clinical Features of ABCA4-Associated Retinopathy in a Japanese Nationwide Cohort. Am J Ophthalmol 2024; 264:36-43. [PMID: 38499139 DOI: 10.1016/j.ajo.2024.03.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Revised: 03/01/2024] [Accepted: 03/11/2024] [Indexed: 03/20/2024]
Abstract
PURPOSE To clarify the genetic and clinical features of Japanese patients with ABCA4-associated retinopathy. DESIGN Retrospective, multicenter cohort study. METHODS Patients with retinal degeneration and biallelic ABCA4 variants were recruited from 13 different hospitals. Whole exome sequencing analysis was used for genetic testing. Comprehensive ophthalmic examinations were performed on matched patients. The primary outcome measure was identifying multimodal retinal imaging findings associated with disease progression. RESULTS This study included 63 patients: 19 with missense/missense, 23 with missense/truncation, and 21 with truncation/truncation genotypes. In total, 62 variants were identified, including 29 novel variants. Six patients had a mild phenotype characterized by foveal-sparing or preserved foveal structure, including 4 with missense/missense and 2 with missense/truncation genotypes. The p.Arg212His variant was the most frequent in patients with mild phenotypes (4/12 alleles). Clinical findings showed a disease duration-dependent worsening of the phenotypic stage. Patients with the truncation/truncation genotype exhibited rapid retinal degeneration within a few years and definite fundus autofluorescence imaging patterns, including hyper autofluorescence at the macula and few or no flecks. CONCLUSIONS Our results indicate that missense/missense or missense/truncation genotypes, including the p.Arg212His variant, are associated with a relatively mild phenotype. In contrast, the truncation/truncation genotype causes rapid and severe retinal degeneration in Japanese patients with ABCA4-associated retinopathy. These data are vital in predicting patient prognosis, guiding genetic counseling, and stratifying patients for future clinical trials.
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Affiliation(s)
- Kei Mizobuchi
- Department of Ophthalmology (K.M., T.H., T.N.), The Jikei University School of Medicine, Tokyo, Japan
| | - Takaaki Hayashi
- Department of Ophthalmology (K.M., T.H., T.N.), The Jikei University School of Medicine, Tokyo, Japan; Department of Ophthalmology, Katsushika Medical Center (T.H.), The Jikei University School of Medicine, Tokyo, Japan.
| | - Koji Tanaka
- Division of Ophthalmology, Department of Visual Sciences (K.T.), Nihon University School of Medicine, Nihon University Hospital, Tokyo, Japan
| | - Kazuki Kuniyoshi
- Department of Ophthalmology (K.K., S.K.), Kindai University Faculty of Medicine, Osaka-sayama, Japan
| | - Yusuke Murakami
- Department of Ophthalmology (Y.M.), Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Natsuko Nakamura
- Department of Ophthalmology (N.N.), The University of Tokyo, Tokyo, Japan
| | - Kaoruko Torii
- Department of Ophthalmology (K.T., Y.H.), Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| | - Atsushi Mizota
- Department of Ophthalmology (A.M.), Teikyo University, Tokyo, Japan
| | - Daiki Sakai
- Department of Ophthalmology (D.S., A.M.), Kobe City Eye Hospital, Kobe, Japan
| | - Akiko Maeda
- Department of Ophthalmology (D.S., A.M.), Kobe City Eye Hospital, Kobe, Japan
| | - Taro Kominami
- Department of Ophthalmology (T.K., S.U., K.M.N.), Nagoya University Graduate School of Medicine, Aichi, Japan
| | - Shinji Ueno
- Department of Ophthalmology (T.K., S.U., K.M.N.), Nagoya University Graduate School of Medicine, Aichi, Japan; Department of Ophthalmology (S.U.), Hirosaki University Graduate School of Medicine, Aomori, Japan
| | - Shunji Kusaka
- Department of Ophthalmology (K.K., S.K.), Kindai University Faculty of Medicine, Osaka-sayama, Japan
| | - Koji M Nishiguchi
- Department of Ophthalmology (T.K., S.U., K.M.N.), Nagoya University Graduate School of Medicine, Aichi, Japan
| | - Yasuhiro Ikeda
- Department of Ophthalmology (Y.I.), Faculty of Medicine, University of Miyazaki, Miyazaki, Japan
| | - Mineo Kondo
- Department of Ophthalmology (M.K.), Mie University Graduate School of Medicine, Mie, Japan
| | - Kazushige Tsunoda
- Division of Vision Research (K.T.), National Institute of Sensory Organs, NHO Tokyo Medical Center, Tokyo, Japan
| | - Yoshihiro Hotta
- Department of Ophthalmology (K.T., Y.H.), Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| | - Tadashi Nakano
- Department of Ophthalmology (K.M., T.H., T.N.), The Jikei University School of Medicine, Tokyo, Japan
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Kulbay M, Tuli N, Akdag A, Kahn Ali S, Qian CX. Optogenetics and Targeted Gene Therapy for Retinal Diseases: Unravelling the Fundamentals, Applications, and Future Perspectives. J Clin Med 2024; 13:4224. [PMID: 39064263 PMCID: PMC11277578 DOI: 10.3390/jcm13144224] [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: 06/18/2024] [Revised: 07/15/2024] [Accepted: 07/15/2024] [Indexed: 07/28/2024] Open
Abstract
With a common aim of restoring physiological function of defective cells, optogenetics and targeted gene therapies have shown great clinical potential and novelty in the branch of personalized medicine and inherited retinal diseases (IRDs). The basis of optogenetics aims to bypass defective photoreceptors by introducing opsins with light-sensing capabilities. In contrast, targeted gene therapies, such as methods based on CRISPR-Cas9 and RNA interference with noncoding RNAs (i.e., microRNA, small interfering RNA, short hairpin RNA), consists of inducing normal gene or protein expression into affected cells. Having partially leveraged the challenges limiting their prompt introduction into the clinical practice (i.e., engineering, cell or tissue delivery capabilities), it is crucial to deepen the fields of knowledge applied to optogenetics and targeted gene therapy. The aim of this in-depth and novel literature review is to explain the fundamentals and applications of optogenetics and targeted gene therapies, while providing decision-making arguments for ophthalmologists. First, we review the biomolecular principles and engineering steps involved in optogenetics and the targeted gene therapies mentioned above by bringing a focus on the specific vectors and molecules for cell signalization. The importance of vector choice and engineering methods are discussed. Second, we summarize the ongoing clinical trials and most recent discoveries for optogenetics and targeted gene therapies for IRDs. Finally, we then discuss the limits and current challenges of each novel therapy. We aim to provide for the first time scientific-based explanations for clinicians to justify the specificity of each therapy for one disease, which can help improve clinical decision-making tasks.
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Affiliation(s)
- Merve Kulbay
- Department of Ophthalmology & Visual Sciences, McGill University, Montreal, QC H4A 3S5, Canada;
| | - Nicolas Tuli
- Faculty of Medicine and Health Sciences, McGill University, Montreal, QC H3G 2M1, Canada (A.A.)
| | - Arjin Akdag
- Faculty of Medicine and Health Sciences, McGill University, Montreal, QC H3G 2M1, Canada (A.A.)
| | - Shigufa Kahn Ali
- Centre de Recherche de l’Hôpital Maisonneuve-Rosemont, Université de Montréal, Montreal, QC H1T 2M4, Canada;
| | - Cynthia X. Qian
- Centre de Recherche de l’Hôpital Maisonneuve-Rosemont, Université de Montréal, Montreal, QC H1T 2M4, Canada;
- Department of Ophthalmology, Centre Universitaire d’Ophtalmologie (CUO), Hôpital Maisonneuve-Rosemont, Université de Montréal, Montreal, QC H1T 2M4, Canada
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3
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Datta P, Rhee KD, Staudt RJ, Thompson JM, Hsu Y, Hassan S, Drack AV, Seo S. Delivering large genes using adeno-associated virus and the CRE-lox DNA recombination system. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.10.588864. [PMID: 38645107 PMCID: PMC11030439 DOI: 10.1101/2024.04.10.588864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/23/2024]
Abstract
Adeno-associated virus (AAV) is a safe and efficient gene delivery vehicle for gene therapies. However, its relatively small packaging capacity limits its use as a gene transfer vector. Here, we describe a strategy to deliver large genes that exceed the AAV's packaging capacity using up to four AAV vectors and the CRE-lox DNA recombination system. We devised novel lox sites by combining non-compatible and reaction equilibrium-modifying lox site variants. These lox sites facilitate sequence-specific and near-unidirectional recombination of AAV vector genomes, enabling efficient reconstitution of up to 16 kb of therapeutic genes in a pre-determined configuration. Using this strategy, we have developed AAV gene therapy vectors to deliver IFT140 , PCDH15 , CEP290 , and CDH23 and demonstrate efficient production of full-length proteins in cultured mammalian cells and mouse retinas. Notably, this approach significantly surpasses the trans-splicing and split-intein-based reconstitution methods in efficiency, requiring lower doses, minimizing or eliminating the production of truncated protein products, and offering flexibility in selecting splitting positions. The CRE-lox approach described here provides a simple and effective platform for producing AAV gene therapy vectors beyond AAV's packaging capacity.
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Fujinami K, Waheed N, Laich Y, Yang P, Fujinami-Yokokawa Y, Higgins JJ, Lu JT, Curtiss D, Clary C, Michaelides M. Stargardt macular dystrophy and therapeutic approaches. Br J Ophthalmol 2024; 108:495-505. [PMID: 37940365 PMCID: PMC10958310 DOI: 10.1136/bjo-2022-323071] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 10/06/2023] [Indexed: 11/10/2023]
Abstract
Stargardt macular dystrophy (Stargardt disease; STGD1; OMIM 248200) is the most prevalent inherited macular dystrophy. STGD1 is an autosomal recessive disorder caused by multiple pathogenic sequence variants in the large ABCA4 gene (OMIM 601691). Major advances in understanding both the clinical and molecular features, as well as the underlying pathophysiology, have culminated in many completed, ongoing and planned human clinical trials of novel therapies.The aims of this concise review are to describe (1) the detailed phenotypic and genotypic characteristics of the disease, multimodal imaging findings, natural history of the disease, and pathogenesis, (2) the multiple avenues of research and therapeutic intervention, including pharmacological, cellular therapies and diverse types of genetic therapies that have either been investigated or are under investigation and (3) the exciting novel therapeutic approaches on the translational horizon that aim to treat STGD1 by replacing the entire 6.8 kb ABCA4 open reading frame.
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Affiliation(s)
- Kaoru Fujinami
- Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, NHO Tokyo Medical Center, Meguro-ku, Tokyo, Japan
- Institute of Ophthalmology, University College London, London, UK
- Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Nadia Waheed
- Department of Ophthalmology, Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Yannik Laich
- Moorfields Eye Hospital NHS Foundation Trust, London, UK
- Eye Center, Medical Center, University of Freiburg Faculty of Medicine, Freiburg, Germany
| | - Paul Yang
- Oregon Health and Science University Casey Eye Institute, Portland, Oregon, USA
| | - Yu Fujinami-Yokokawa
- Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, NHO Tokyo Medical Center, Meguro-ku, Tokyo, Japan
- Institute of Ophthalmology, University College London, London, UK
- Department of Health Policy and Management, Keio University School of Medicine Graduate School of Medicine, Shinjuku-ku, Tokyo, Japan
| | | | - Jonathan T Lu
- SalioGen Therapeutics Inc, Lexington, Massachusetts, USA
| | - Darin Curtiss
- Applied Genetic Technologies Corporation, Alachua, Florida, USA
| | - Cathryn Clary
- SalioGen Therapeutics Inc, Lexington, Massachusetts, USA
| | - Michel Michaelides
- Institute of Ophthalmology, University College London, London, UK
- Moorfields Eye Hospital NHS Foundation Trust, London, UK
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5
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郑 婷, 朱 倍, 王 智, 李 青. [Gene therapy strategies and prospects for neurofibromatosis type 1]. ZHONGGUO XIU FU CHONG JIAN WAI KE ZA ZHI = ZHONGGUO XIUFU CHONGJIAN WAIKE ZAZHI = CHINESE JOURNAL OF REPARATIVE AND RECONSTRUCTIVE SURGERY 2024; 38:1-8. [PMID: 38225833 PMCID: PMC10796236 DOI: 10.7507/1002-1892.202309071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 11/20/2023] [Accepted: 11/22/2023] [Indexed: 01/17/2024]
Abstract
Objective To summarize the gene therapy strategies for neurofibromatosis type 1 (NF1) and related research progress. Methods The recent literature on gene therapy for NF1 at home and abroad was reviewed. The structure and function of the NF1 gene and its mutations were analyzed, and the current status as well as future prospects of the transgenic therapy and gene editing strategies were summarized. Results NF1 is an autosomal dominantly inherited tumor predisposition syndrome caused by mutations in the NF1 tumor suppressor gene, which impair the function of the neurofibromin and lead to the disease. It has complex clinical manifestations and is not yet curable. Gene therapy strategies for NF1 are still in the research and development stage. Existing studies on the transgenic therapy for NF1 have mainly focused on the construction and expression of the GTPase-activating protein-related domain in cells that lack of functional neurofibromin, confirming the feasibility of the transgenic therapy for NF1. Future research may focus on split adeno-associated virus (AAV) gene delivery, oversized AAV gene delivery, and the development of new vectors for targeted delivery of full-length NF1 cDNA. In addition, the gene editing tools of the new generation have great potential to treat monogenic genetic diseases such as NF1, but need to be further validated in terms of efficiency and safety. Conclusion Gene therapy, including both the transgenic therapy and gene editing, is expected to become an important new therapeutic approach for NF1 patients.
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Affiliation(s)
- 婷婷 郑
- 上海交通大学医学院附属第九人民医院整复外科(上海 200011)Department of Plastic and Reconstructive Surgery, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, P. R. China
- 上海交通大学医学院附属第九人民医院Ⅰ型神经纤维瘤病诊疗中心(上海 200011)Neurofibromatosis Type 1 Center, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, P. R. China
| | - 倍瑶 朱
- 上海交通大学医学院附属第九人民医院整复外科(上海 200011)Department of Plastic and Reconstructive Surgery, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, P. R. China
- 上海交通大学医学院附属第九人民医院Ⅰ型神经纤维瘤病诊疗中心(上海 200011)Neurofibromatosis Type 1 Center, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, P. R. China
| | - 智超 王
- 上海交通大学医学院附属第九人民医院整复外科(上海 200011)Department of Plastic and Reconstructive Surgery, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, P. R. China
- 上海交通大学医学院附属第九人民医院Ⅰ型神经纤维瘤病诊疗中心(上海 200011)Neurofibromatosis Type 1 Center, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, P. R. China
| | - 青峰 李
- 上海交通大学医学院附属第九人民医院整复外科(上海 200011)Department of Plastic and Reconstructive Surgery, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, P. R. China
- 上海交通大学医学院附属第九人民医院Ⅰ型神经纤维瘤病诊疗中心(上海 200011)Neurofibromatosis Type 1 Center, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, P. R. China
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Schultz A, Cheng SY, Kirchner E, Costello S, Miettinen H, Chaverra M, King C, George L, Zhao X, Narasimhan J, Weetall M, Slaugenhaupt S, Morini E, Punzo C, Lefcort F. Reduction of retinal ganglion cell death in mouse models of familial dysautonomia using AAV-mediated gene therapy and splicing modulators. Sci Rep 2023; 13:18600. [PMID: 37903840 PMCID: PMC10616160 DOI: 10.1038/s41598-023-45376-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2023] [Accepted: 10/18/2023] [Indexed: 11/01/2023] Open
Abstract
Familial dysautonomia (FD) is a rare neurodevelopmental and neurodegenerative disease caused by a splicing mutation in the Elongator Acetyltransferase Complex Subunit 1 (ELP1) gene. The reduction in ELP1 mRNA and protein leads to the death of retinal ganglion cells (RGCs) and visual impairment in all FD patients. Currently patient symptoms are managed, but there is no treatment for the disease. We sought to test the hypothesis that restoring levels of Elp1 would thwart the death of RGCs in FD. To this end, we tested the effectiveness of two therapeutic strategies for rescuing RGCs. Here we provide proof-of-concept data that gene replacement therapy and small molecule splicing modifiers effectively reduce the death of RGCs in mouse models for FD and provide pre-clinical foundational data for translation to FD patients.
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Affiliation(s)
- Anastasia Schultz
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, USA
| | - Shun-Yun Cheng
- Department of Ophthalmology, Neurobiology and Gene Therapy Center, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Emily Kirchner
- Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Boston, MA, USA
| | - Stephanann Costello
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, USA
| | - Heini Miettinen
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, USA
| | - Marta Chaverra
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, USA
| | - Colin King
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, USA
| | - Lynn George
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, USA
- Department of Biological and Physical Science, Montana State University Billings, Billings, MT, USA
| | - Xin Zhao
- PTC Therapeutics, Inc., South Plainfield, NJ, 07080, USA
| | | | - Marla Weetall
- PTC Therapeutics, Inc., South Plainfield, NJ, 07080, USA
| | - Susan Slaugenhaupt
- Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Boston, MA, USA
- Department of Neurology, Massachusetts General Hospital Research Institute and Harvard Medical School, Boston, MA, USA
| | - Elisabetta Morini
- Center for Genomic Medicine, Massachusetts General Hospital Research Institute, Boston, MA, USA
- Department of Neurology, Massachusetts General Hospital Research Institute and Harvard Medical School, Boston, MA, USA
| | - Claudio Punzo
- Department of Ophthalmology, Neurobiology and Gene Therapy Center, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Frances Lefcort
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, USA.
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7
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Riedmayr LM, Hinrichsmeyer KS, Thalhammer SB, Mittas DM, Karguth N, Otify DY, Böhm S, Weber VJ, Bartoschek MD, Splith V, Brümmer M, Ferreira R, Boon N, Wögenstein GM, Grimm C, Wijnholds J, Mehlfeld V, Michalakis S, Fenske S, Biel M, Becirovic E. mRNA trans-splicing dual AAV vectors for (epi)genome editing and gene therapy. Nat Commun 2023; 14:6578. [PMID: 37852949 PMCID: PMC10584818 DOI: 10.1038/s41467-023-42386-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Accepted: 10/10/2023] [Indexed: 10/20/2023] Open
Abstract
Large genes including several CRISPR-Cas modules like gene activators (CRISPRa) require dual adeno-associated viral (AAV) vectors for an efficient in vivo delivery and expression. Current dual AAV vector approaches have important limitations, e.g., low reconstitution efficiency, production of alien proteins, or low flexibility in split site selection. Here, we present a dual AAV vector technology based on reconstitution via mRNA trans-splicing (REVeRT). REVeRT is flexible in split site selection and can efficiently reconstitute different split genes in numerous in vitro models, in human organoids, and in vivo. Furthermore, REVeRT can functionally reconstitute a CRISPRa module targeting genes in various mouse tissues and organs in single or multiplexed approaches upon different routes of administration. Finally, REVeRT enabled the reconstitution of full-length ABCA4 after intravitreal injection in a mouse model of Stargardt disease. Due to its flexibility and efficiency REVeRT harbors great potential for basic research and clinical applications.
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Affiliation(s)
- Lisa Maria Riedmayr
- Department of Pharmacy - Center for Drug Research, LMU Munich, Munich, 81377, Germany
| | | | | | - David Manuel Mittas
- Department of Pharmacy - Center for Drug Research, LMU Munich, Munich, 81377, Germany
| | - Nina Karguth
- Department of Pharmacy - Center for Drug Research, LMU Munich, Munich, 81377, Germany
| | - Dina Yehia Otify
- Department of Pharmacy - Center for Drug Research, LMU Munich, Munich, 81377, Germany
| | | | - Valentin Johannes Weber
- Laboratory for Retinal Gene Therapy, Department of Ophthalmology, University Hospital Zurich, University of Zurich, Schlieren, 8952, Switzerland
| | | | | | - Manuela Brümmer
- Department of Pharmacy - Center for Drug Research, LMU Munich, Munich, 81377, Germany
| | - Raphael Ferreira
- Genetics Department, Harvard Medical School, Boston, MA, 02115, USA
| | - Nanda Boon
- Department of Ophthalmology, Leiden University Medical Center (LUMC), 2333 ZA, Leiden, Netherlands
| | - Gabriele Maria Wögenstein
- Laboratory for Retinal Cell Biology, Department of Ophthalmology, University Hospital Zurich, University of Zurich, Schlieren, 8952, Switzerland
| | - Christian Grimm
- Laboratory for Retinal Cell Biology, Department of Ophthalmology, University Hospital Zurich, University of Zurich, Schlieren, 8952, Switzerland
| | - Jan Wijnholds
- Department of Ophthalmology, Leiden University Medical Center (LUMC), 2333 ZA, Leiden, Netherlands
- Netherlands Institute for Neuroscience, Institute of the Royal Netherlands Academy of Arts and Sciences (KNAW), 1105 BA, Amsterdam, Netherlands
| | - Verena Mehlfeld
- Department of Pharmacy - Center for Drug Research, LMU Munich, Munich, 81377, Germany
| | - Stylianos Michalakis
- Department of Ophthalmology, University Hospital, LMU Munich, 80336, Munich, Germany
| | - Stefanie Fenske
- Department of Pharmacy - Center for Drug Research, LMU Munich, Munich, 81377, Germany
- German Center for Cardiovascular Research (DZHK), partner site Munich Heart Alliance, Munich, 81377, Germany
| | - Martin Biel
- Department of Pharmacy - Center for Drug Research, LMU Munich, Munich, 81377, Germany
| | - Elvir Becirovic
- Laboratory for Retinal Gene Therapy, Department of Ophthalmology, University Hospital Zurich, University of Zurich, Schlieren, 8952, Switzerland.
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8
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Xia J, Gu L, Pan Q. The landscape of basic gene therapy approaches in inherited retinal dystrophies. FRONTIERS IN OPHTHALMOLOGY 2023; 3:1193595. [PMID: 38983091 PMCID: PMC11182181 DOI: 10.3389/fopht.2023.1193595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2023] [Accepted: 06/09/2023] [Indexed: 07/11/2024]
Abstract
The study of gene therapies has been of particular interest in recent decades due to their promising potential to slow or even rescue the degeneration of the retina in inherited retinal dystrophies (IRDs). Here, we review the current approaches to gene therapy trials on IRDs, including the selection of animal models, therapeutic window, vectors and dosages. Mice are typically the first choice of animal models and recombinant adeno-associated virus (rAAV) of serotype 8 is the most common vector for loss-of-function IRDs. Furthermore, the therapeutic window should be considered to ensure efficacy before retinal degeneration occurs if possible, and dosages must be tailored to each approach.
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Affiliation(s)
| | | | - Qing Pan
- The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
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Whelan L, Dockery A, Stephenson KAJ, Zhu J, Kopčić E, Post IJM, Khan M, Corradi Z, Wynne N, O' Byrne JJ, Duignan E, Silvestri G, Roosing S, Cremers FPM, Keegan DJ, Kenna PF, Farrar GJ. Detailed analysis of an enriched deep intronic ABCA4 variant in Irish Stargardt disease patients. Sci Rep 2023; 13:9380. [PMID: 37296172 PMCID: PMC10256698 DOI: 10.1038/s41598-023-35889-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Accepted: 05/25/2023] [Indexed: 06/12/2023] Open
Abstract
Over 15% of probands in a large cohort of more than 1500 inherited retinal degeneration patients present with a clinical diagnosis of Stargardt disease (STGD1), a recessive form of macular dystrophy caused by biallelic variants in the ABCA4 gene. Participants were clinically examined and underwent either target capture sequencing of the exons and some pathogenic intronic regions of ABCA4, sequencing of the entire ABCA4 gene or whole genome sequencing. ABCA4 c.4539 + 2028C > T, p.[= ,Arg1514Leufs*36] is a pathogenic deep intronic variant that results in a retina-specific 345-nucleotide pseudoexon inclusion. Through analysis of the Irish STGD1 cohort, 25 individuals across 18 pedigrees harbour ABCA4 c.4539 + 2028C > T and another pathogenic variant. This includes, to the best of our knowledge, the only two homozygous patients identified to date. This provides important evidence of variant pathogenicity for this deep intronic variant, highlighting the value of homozygotes for variant interpretation. 15 other heterozygous incidents of this variant in patients have been reported globally, indicating significant enrichment in the Irish population. We provide detailed genetic and clinical characterization of these patients, illustrating that ABCA4 c.4539 + 2028C > T is a variant of mild to intermediate severity. These results have important implications for unresolved STGD1 patients globally with approximately 10% of the population in some western countries claiming Irish heritage. This study exemplifies that detection and characterization of founder variants is a diagnostic imperative.
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Affiliation(s)
- Laura Whelan
- The School of Genetics and Microbiology, Trinity College Dublin, Dublin 2, Ireland.
| | - Adrian Dockery
- The School of Genetics and Microbiology, Trinity College Dublin, Dublin 2, Ireland
- Next Generation Sequencing Laboratory, Pathology Department, The Mater Misericordiae University Hospital, Dublin 7, Ireland
| | - Kirk A J Stephenson
- Department of Ophthalmology, Royal Victoria Eye and Ear Hospital, Dublin 2, Ireland
- Mater Clinical Ophthalmic Genetics Unit, The Mater Misericordiae University Hospital, Dublin 7, Ireland
| | - Julia Zhu
- Mater Clinical Ophthalmic Genetics Unit, The Mater Misericordiae University Hospital, Dublin 7, Ireland
| | - Ella Kopčić
- The School of Genetics and Microbiology, Trinity College Dublin, Dublin 2, Ireland
| | - Iris J M Post
- The School of Genetics and Microbiology, Trinity College Dublin, Dublin 2, Ireland
| | - Mubeen Khan
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands
- Language and Genetics Department, Max Planck Institute for Psycholinguistics, Nijmegen, The Netherlands
- International Max Planck Research School for Language Sciences, Max Planck Institute for Psycholinguistics, Nijmegen, The Netherlands
| | - Zelia Corradi
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands
- Academic Alliance Genetics, Radboud University Medical Center, Nijmegen, and Maastricht University Medical Center+, Maastricht, The Netherlands
| | - Niamh Wynne
- Department of Ophthalmology, Royal Victoria Eye and Ear Hospital, Dublin 2, Ireland
| | - James J O' Byrne
- Mater Clinical Ophthalmic Genetics Unit, The Mater Misericordiae University Hospital, Dublin 7, Ireland
- International Max Planck Research School for Language Sciences, Max Planck Institute for Psycholinguistics, Nijmegen, The Netherlands
- National Centre for Inherited Metabolic Disorders, The Mater Misericordiae University Hospital, Dublin 7, Ireland
- School of Medicine, Trinity College Dublin, Dublin 2, Ireland
| | - Emma Duignan
- Department of Ophthalmology, Royal Victoria Eye and Ear Hospital, Dublin 2, Ireland
| | - Giuliana Silvestri
- Centre for Experimental Medicine, Queen's University Belfast, Belfast, Northern Ireland, UK
- School of Medicine, University College Dublin, Dublin 4, Ireland
- Department of Ophthalmology, The Royal Victoria Hospital, Belfast, Northern Ireland, UK
| | - Susanne Roosing
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands
- Academic Alliance Genetics, Radboud University Medical Center, Nijmegen, and Maastricht University Medical Center+, Maastricht, The Netherlands
| | - Frans P M Cremers
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands
- Academic Alliance Genetics, Radboud University Medical Center, Nijmegen, and Maastricht University Medical Center+, Maastricht, The Netherlands
| | - David J Keegan
- Mater Clinical Ophthalmic Genetics Unit, The Mater Misericordiae University Hospital, Dublin 7, Ireland
| | - Paul F Kenna
- The School of Genetics and Microbiology, Trinity College Dublin, Dublin 2, Ireland
- Department of Ophthalmology, Royal Victoria Eye and Ear Hospital, Dublin 2, Ireland
| | - G Jane Farrar
- The School of Genetics and Microbiology, Trinity College Dublin, Dublin 2, Ireland
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10
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Schultz A, Cheng SY, Kirchner E, Costello S, Miettinen H, Chaverra M, King C, George L, Zhao X, Narasimhan J, Weetall M, Slaugenhaupt S, Morini E, Punzo C, Lefcort F. Reduction of retinal ganglion cell death in mouse models of familial dysautonomia using AAV-mediated gene therapy and splicing modulators. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.22.541535. [PMID: 37293016 PMCID: PMC10245894 DOI: 10.1101/2023.05.22.541535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Familial dysautonomia (FD) is a rare neurodevelopmental and neurodegenerative disease caused by a splicing mutation in the Elongator Acetyltransferase Complex Subunit 1 ( ELP1 ) gene. The reduction in ELP1 mRNA and protein leads to the death of retinal ganglion cells (RGCs) and visual impairment in all FD patients. Currently, patient symptoms are managed, but there is no treatment for the disease. We sought to test the hypothesis that restoring levels of Elp1 would thwart the death of RGCs in FD. To this end, we tested the effectiveness of two therapeutic strategies for rescuing RGCs. Here we provide proof-of-concept data that gene replacement therapy and small molecule splicing modifiers effectively reduce the death of RGCs in mouse models for FD and provide pre-clinical data foundation for translation to FD patients.
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Cehajic-Kapetanovic J, Singh MS, Zrenner E, MacLaren RE. Bioengineering strategies for restoring vision. Nat Biomed Eng 2023; 7:387-404. [PMID: 35102278 DOI: 10.1038/s41551-021-00836-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 11/30/2021] [Indexed: 12/15/2022]
Abstract
Late-stage retinal degenerative disease involving photoreceptor loss can be treated by optogenetic therapy, cell transplantation and retinal prostheses. These approaches aim to restore light sensitivity to the retina as well as visual perception by integrating neuronal responses for transmission to the cortex. In age-related macular degeneration, some cell-based therapies also aim to restore photoreceptor-supporting tissue to prevent complete photoreceptor loss. In the earlier stages of degeneration, gene-replacement therapy could attenuate retinal-disease progression and reverse loss of function. And gene-editing strategies aim to correct the underlying genetic defects. In this Review, we highlight the most promising gene therapies, cell therapies and retinal prostheses for the treatment of retinal disease, discuss the benefits and drawbacks of each treatment strategy and the factors influencing whether functional tissue is reconstructed and repaired or replaced with an electronic device, and summarize upcoming technologies for enhancing the restoration of vision.
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Affiliation(s)
- Jasmina Cehajic-Kapetanovic
- Nuffield Laboratory of Ophthalmology, University of Oxford, Oxford, UK.
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK.
| | | | - Eberhart Zrenner
- Institute for Ophthalmic Research, Center for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Robert E MacLaren
- Nuffield Laboratory of Ophthalmology, University of Oxford, Oxford, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
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12
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Wu KY, Kulbay M, Toameh D, Xu AQ, Kalevar A, Tran SD. Retinitis Pigmentosa: Novel Therapeutic Targets and Drug Development. Pharmaceutics 2023; 15:685. [PMID: 36840007 PMCID: PMC9963330 DOI: 10.3390/pharmaceutics15020685] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 02/12/2023] [Accepted: 02/16/2023] [Indexed: 02/19/2023] Open
Abstract
Retinitis pigmentosa (RP) is a heterogeneous group of hereditary diseases characterized by progressive degeneration of retinal photoreceptors leading to progressive visual decline. It is the most common type of inherited retinal dystrophy and has a high burden on both patients and society. This condition causes gradual loss of vision, with its typical manifestations including nyctalopia, concentric visual field loss, and ultimately bilateral central vision loss. It is one of the leading causes of visual disability and blindness in people under 60 years old and affects over 1.5 million people worldwide. There is currently no curative treatment for people with RP, and only a small group of patients with confirmed RPE65 mutations are eligible to receive the only gene therapy on the market: voretigene neparvovec. The current therapeutic armamentarium is limited to retinoids, vitamin A supplements, protection from sunlight, visual aids, and medical and surgical interventions to treat ophthalmic comorbidities, which only aim to slow down the progression of the disease. Considering such a limited therapeutic landscape, there is an urgent need for developing new and individualized therapeutic modalities targeting retinal degeneration. Although the heterogeneity of gene mutations involved in RP makes its target treatment development difficult, recent fundamental studies showed promising progress in elucidation of the photoreceptor degeneration mechanism. The discovery of novel molecule therapeutics that can selectively target specific receptors or specific pathways will serve as a solid foundation for advanced drug development. This article is a review of recent progress in novel treatment of RP focusing on preclinical stage fundamental research on molecular targets, which will serve as a starting point for advanced drug development. We will review the alterations in the molecular pathways involved in the development of RP, mainly those regarding endoplasmic reticulum (ER) stress and apoptotic pathways, maintenance of the redox balance, and genomic stability. We will then discuss the therapeutic approaches under development, such as gene and cell therapy, as well as the recent literature identifying novel potential drug targets for RP.
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Affiliation(s)
- Kevin Y. Wu
- Division of Ophthalmology, Department of Surgery, University of Sherbrooke, Sherbrooke, QC J1G 2E8, Canada
| | - Merve Kulbay
- Faculty of Medicine, University of Montreal, Montreal, QC H3T 1J4, Canada
| | - Dana Toameh
- Faculty of Medicine, McGill University, Montreal, QC H3G 2M1, Canada
| | - An Qi Xu
- Faculty of Medicine, University of Montreal, Montreal, QC H3T 1J4, Canada
| | - Ananda Kalevar
- Division of Ophthalmology, Department of Surgery, University of Sherbrooke, Sherbrooke, QC J1G 2E8, Canada
| | - Simon D. Tran
- Faculty of Dental Medicine and Oral Health Sciences, McGill University, Montreal, QC H3A 1G1, Canada
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13
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Future Perspectives of Prime Editing for the Treatment of Inherited Retinal Diseases. Cells 2023; 12:cells12030440. [PMID: 36766782 PMCID: PMC9913839 DOI: 10.3390/cells12030440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 01/24/2023] [Accepted: 01/27/2023] [Indexed: 01/31/2023] Open
Abstract
Inherited retinal diseases (IRD) are a clinically and genetically heterogenous group of diseases and a leading cause of blindness in the working-age population. Even though gene augmentation therapies have shown promising results, they are only feasible to treat a small number of autosomal recessive IRDs, because the size of the gene is limited by the vector used. DNA editing however could potentially correct errors regardless of the overall size of the gene and might also be used to correct dominant mutations. Prime editing is a novel CRISPR/Cas9 based gene editing tool that enables precise correction of point mutations, insertions, and deletions without causing double strand DNA breaks. Due to its versatility and precision this technology may be a potential treatment option for virtually all genetic causes of IRD. Since its initial description, the prime editing technology has been further improved, resulting in higher efficacy and a larger target scope. Additionally, progress has been achieved concerning the size-related delivery issue of the prime editor components. This review aims to give an overview of these recent advancements and discusses prime editing as a potential treatment for IRDs.
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14
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Yee T, Wert KJ. Base and Prime Editing in the Retina-From Preclinical Research toward Human Clinical Trials. Int J Mol Sci 2022; 23:ijms232012375. [PMID: 36293232 PMCID: PMC9604474 DOI: 10.3390/ijms232012375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 10/11/2022] [Accepted: 10/13/2022] [Indexed: 11/07/2022] Open
Abstract
Inherited retinal diseases (IRDs) are a clinically and genetically heterogeneous group of diseases that are one of the leading causes of vision loss in young and aged individuals. IRDs are mainly caused by a loss of the post-mitotic photoreceptor neurons of the retina, or by the degeneration of the retinal pigment epithelium. Unfortunately, once these cells are damaged, it is irreversible and leads to permanent vision impairment. Thought to be previously incurable, gene therapy has been rapidly evolving to be a potential treatment to prevent further degeneration of the retina and preserve visual function. The development of clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein 9 (Cas9) base and prime editors have increased the capabilities of the genome editing toolbox in recent years. Both base and prime editors evade the creation of double-stranded breaks in deoxyribonucleic acid (DNA) and the requirement of donor template of DNA for repair, which make them advantageous methods in developing clinical therapies. In addition, establishing a permanent edit within the genome could be better suited for patients with progressive degeneration. In this review, we will summarize published uses of successful base and prime editing in treating IRDs.
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Affiliation(s)
- Tiffany Yee
- Department of Ophthalmology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Katherine J. Wert
- Department of Ophthalmology, UT Southwestern Medical Center, Dallas, TX 75390, USA
- Peter O’Donnell Jr. Brain Institute, UT Southwestern Medical Center, Dallas, TX 75390, USA
- Department of Molecular Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA
- Hamon Center for Regenerative Science and Medicine, UT Southwestern Medical Center, Dallas, TX 75390, USA
- Correspondence: ; Tel.: +1-214-648-6192
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15
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Staurenghi F, McClements ME, Salman A, MacLaren RE. Minicircle Delivery to the Neural Retina as a Gene Therapy Approach. Int J Mol Sci 2022; 23:11673. [PMID: 36232975 PMCID: PMC9569440 DOI: 10.3390/ijms231911673] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 09/26/2022] [Accepted: 09/28/2022] [Indexed: 11/07/2022] Open
Abstract
Non-viral gene therapy has the potential to overcome several shortcomings in viral vector-based therapeutics. Methods of in vivo plasmid delivery have developed over recent years to increase the efficiency of non-viral gene transfer, yet further improvements still need to be made to improve their translational capacity. Gene therapy advances for inherited retinal disease have been particularly prominent over the recent decade but overcoming physical and physiological barriers present in the eye remains a key obstacle in the field of non-viral ocular drug delivery. Minicircles are circular double-stranded DNA vectors that contain expression cassettes devoid of bacterial DNA, thereby limiting the risks of innate immune responses induced by such elements. To date, they have not been extensively used in pre-clinical studies yet remain a viable vector option for the treatment of inherited retinal disease. Here, we explore the potential of minicircle DNA delivery to the neural retina as a gene therapy approach. We consider the advantages of minicircles as gene therapy vectors as well as review the challenges involved in optimising their delivery to the neural retina.
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Affiliation(s)
- Federica Staurenghi
- Nuffield Laboratory of Ophthalmology, Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK
| | - Michelle E. McClements
- Nuffield Laboratory of Ophthalmology, Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK
| | - Ahmed Salman
- Nuffield Laboratory of Ophthalmology, Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK
| | - Robert E. MacLaren
- Nuffield Laboratory of Ophthalmology, Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK
- Oxford University Hospital, Oxford OX3 9DU, UK
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16
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Major L, McClements ME, MacLaren RE. New CRISPR Tools to Correct Pathogenic Mutations in Usher Syndrome. Int J Mol Sci 2022; 23:ijms231911669. [PMID: 36232969 PMCID: PMC9569511 DOI: 10.3390/ijms231911669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 09/28/2022] [Accepted: 09/29/2022] [Indexed: 11/16/2022] Open
Abstract
Inherited retinal degenerations are a leading cause of blindness in the UK. Significant advances have been made to tackle this issue in recent years, with a pioneering FDA approved gene therapy treatment (Luxturna®), which targets a loss of function mutation in the RPE65 gene. However, there remain notable shortcomings to this form of gene replacement therapy. In particular, the lack of viability for gene sequences exceeding the 4.7 kb adeno-associated virus (AAV) packaging limit or for toxic gain of function mutations. The USH2A gene at ~15.7 kb for instance is too large for AAV delivery: a safe and effective vehicle capable of transducing photoreceptor cells for gene replacement therapy. Usher Syndrome is a clinically and genetically heterogenous deaf-blindness syndrome with autosomal recessive inheritance. The USH2A gene encodes the protein usherin, which localises to the photoreceptor cilium and cochlear hair cells. Mutations in the USH2A gene cause Usher Syndrome type II (USH2), which is the most common subtype of Usher Syndrome and the focus of this review. To date, researchers have been unable to create an efficient, safe editing tool that is small enough to fit inside a single AAV vector for delivery into human cells. This article reviews the potential of CRISPR technology, derived from bacterial defence mechanisms, to overcome these challenges; delivering tools to precisely edit and correct small insertions, deletions and base transitions in USH2A without the need to deliver the full-length gene. Such an ultra-compact therapy could make strides in combating a significant cause of blindness in young people.
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Affiliation(s)
- Lauren Major
- Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford OX3 9DU, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, UK
- Correspondence:
| | - Michelle E. McClements
- Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford OX3 9DU, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, UK
| | - Robert E. MacLaren
- Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford OX3 9DU, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, UK
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Sun D, Sun W, Gao SQ, Lehrer J, Naderi A, Wei C, Lee S, Schilb AL, Scheidt J, Hall RC, Traboulsi EI, Palczewski K, Lu ZR. Effective gene therapy of Stargardt disease with PEG-ECO/ pGRK1-ABCA4-S/MAR nanoparticles. MOLECULAR THERAPY. NUCLEIC ACIDS 2022; 29:823-835. [PMID: 36159595 PMCID: PMC9463552 DOI: 10.1016/j.omtn.2022.08.026] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/27/2022] [Accepted: 08/17/2022] [Indexed: 01/07/2023]
Abstract
Stargardt disease (STGD) is the most common form of inherited retinal genetic disorders and is often caused by mutations in ABCA4. Gene therapy has the promise to effectively treat monogenic retinal disorders. However, clinically approved adeno-associated virus (AAV) vectors do not have a loading capacity for large genes, such as ABCA4. Self-assembly nanoparticles composed of (1-aminoethyl)iminobis[N-(oleoylcysteinyl-1-amino-ethyl)propionamide (ECO; a multifunctional pH-sensitive/ionizable amino lipid) and plasmid DNA produce gene transfection comparable with or better than the AAV2 capsid. Stable PEG-ECO/pGRK1-ABCA4-S/MAR nanoparticles produce specific and prolonged expression of ABCA4 in the photoreceptors of Abca4 -/- mice and significantly inhibit accumulation of toxic A2E in the eye. Multiple subretinal injections enhance gene expression and therapeutic efficacy with an approximately 69% reduction in A2E accumulation in Abca4 -/- mice after 3 doses. Very mild inflammation was observed after multiple injections of the nanoparticles. PEG-ECO/pGRK1-ABCA4-S/MAR nanoparticles are a promising non-viral mediated gene therapy modality for STGD type 1 (STGD1).
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Affiliation(s)
- Da Sun
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Wenyu Sun
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Song-Qi Gao
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Jonathan Lehrer
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Amirreza Naderi
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Cheng Wei
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Sangjoon Lee
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Andrew L. Schilb
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Josef Scheidt
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Ryan C. Hall
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Elias I. Traboulsi
- Department of Pediatric Ophthalmology and Center for Genetic Eye Diseases, Cole Eye Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44106, USA
| | - Krzysztof Palczewski
- Gavin Herbert Eye Institute, Department of Ophthalmology, Departments of Physiology and Biophysics, Chemistry, and Molecular Biology and Biochemistry, University of California Irvine, Irvine, CA 92697, USA
| | - Zheng-Rong Lu
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
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18
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Marrone L, Marchi PM, Azzouz M. Circumventing the packaging limit of AAV-mediated gene replacement therapy for neurological disorders. Expert Opin Biol Ther 2022; 22:1163-1176. [PMID: 34904932 DOI: 10.1080/14712598.2022.2012148] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 11/25/2021] [Indexed: 12/19/2022]
Abstract
INTRODUCTION Gene therapy provides the exciting opportunity of a curative single treatment for devastating diseases, eradicating the need for chronic medication. Adeno-associated viruses (AAVs) are among the most attractive vector carriers for gene replacement in vivo. Yet, despite the success of recent AAV-based clinical trials, the clinical use of these vectors has been limited. For instance, the AAV packaging capacity is restricted to ~4.7 kb, making it a substantial challenge to deliver large gene products. AREAS COVERED In this review, we explore established and emerging strategies that circumvent the packaging limit of AAVs to make them effective vehicles for gene replacement therapy of monogenic disorders, with a particular focus on diseases affecting the nervous system. We report historical references, design remarks, as well as strengths and weaknesses of these approaches. We additionally discuss examples of neurological disorders for which such strategies have been attempted. EXPERT OPINION The field of AAV-gene therapy has experienced enormous advancements in the last decade. However, there is still ample space for improvement aimed at overcoming existing challenges that are slowing down the progressive trajectory of this field.
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Affiliation(s)
- Lara Marrone
- Department of Neuroscience, Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, Sheffield, UK
| | - Paolo M Marchi
- Department of Neuroscience, Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, Sheffield, UK
| | - Mimoun Azzouz
- Department of Neuroscience, Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, Sheffield, UK
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19
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CRISPR DNA Base Editing Strategies for Treating Retinitis Pigmentosa Caused by Mutations in Rhodopsin. Genes (Basel) 2022; 13:genes13081327. [PMID: 35893064 PMCID: PMC9330713 DOI: 10.3390/genes13081327] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 07/20/2022] [Accepted: 07/22/2022] [Indexed: 01/25/2023] Open
Abstract
Retinitis pigmentosa (RP) is the most common group of inherited retinal degenerations and pathogenic variants in the Rhodopsin (RHO) gene are major cause for autosomal dominant RP (adRP). Despite extensive attempts to treat RHO-associated adRP, standardized curative treatment is still lacking. Recently developed base editors offer an exciting opportunity to correct pathogenic single nucleotide variants and are currently able to correct all transition variants and some transversion variants. In this study, we analyzed previously reported pathogenic RHO variants (n = 247) for suitable PAM sites for currently available base editors utilizing the Streptococcus pyogenes Cas9 (SpCas9), Staphylococcus aureus Cas9 (SaCas9) or the KKH variant of SaCas9 (KKH-SaCas9) to assess DNA base editing as a treatment option for RHO-associated adRP. As a result, 55% of all the analyzed variants could, in theory, be corrected with base editors, however, PAM sites were available for only 32% of them and unwanted bystander edits were predicted for the majority of the designed guide RNAs. As a conclusion, base editing offers exciting possibilities to treat RHO-associated adRP in the future, but further research is needed to develop base editing constructs that will provide available PAM sites for more variants and that will not introduce potentially harmful bystander edits.
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Maturana CJ, Verpeut JL, Engel EA. Single-Cell Quantification of Triple-AAV Vector Genomes Coexpressed in Neurons. Curr Protoc 2022; 2:e430. [PMID: 35616444 DOI: 10.1002/cpz1.430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Adeno-associated viruses (AAVs) are one of the most widely used types of viral vectors for research and gene therapy. AAV vectors are safe, have a low immunogenic profile, and provide efficient and long-term transgene expression in a variety of tissues and organs targeted by a specific serotype. Despite these unique features, therapeutic applications, as well as basic research studies, of AAVs have been limited by their packaging capacity of less than 5 kb. Multiple strategies have been explored to deliver large genes. One strategy is to split large transgenes into two or three fragments and package them into separate AAV capsids, generating dual or triple AAV vectors. Combining the fragments potentially allows reconstitution of an mRNA transcript containing the complete sequence of transgene in the same cell. The success of AAVs as vectors for the delivery of large or multiple genes depends directly on the efficiency of co-transduction. Here, we describe a method to measure the efficacy of codelivery, quantifying the number of AAV vectors per cell. We detail how to calculate the average number of incoming AAV genomes in neurons, given the distribution of cell fluorescence across in vitro and in vivo experimental models. To validate the method, we simulated a triple AAV strategy using three fluorescent-protein-encoding genes. We provide a general protocol for constructing plasmids and producing and purifying AAV vectors. We also include a protocol for triple AAV vector co-transduction in primary neuronal cultures and mouse brain. The method can be applied to multiple organs and tissues for the treatment of disorders caused by mutations in multiple or large genes. These protocols will be useful for researchers working to develop and improve new gene delivery technologies. © 2022 Wiley Periodicals LLC. Basic Protocol 1: Construction of AAV plasmids and production of AAVs Basic Protocol 2: AAV transduction of primary superior cervical ganglia (SCG) neuronal cultures Basic Protocol 3: Mouse surgery, AAV injection, and tissue collection and processing Basic Protocol 4: Image analysis and AAV genome quantification.
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Affiliation(s)
- Carola J Maturana
- Princeton Neuroscience Institute, Princeton University, Princeton, New Jersey
| | - Jessica L Verpeut
- Princeton Neuroscience Institute, Princeton University, Princeton, New Jersey
| | - Esteban A Engel
- Princeton Neuroscience Institute, Princeton University, Princeton, New Jersey
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21
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McClements ME, Steward H, Atkin W, Goode EA, Gándara C, Chichagova V, MacLaren RE. Tropism of AAV Vectors in Photoreceptor-Like Cells of Human iPSC-Derived Retinal Organoids. Transl Vis Sci Technol 2022; 11:3. [PMID: 35377942 PMCID: PMC8994202 DOI: 10.1167/tvst.11.4.3] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Purpose To expand the use of human retinal organoids from induced pluripotent stem cells (iPSCs) as an in vitro model of the retina for assessing gene therapy treatments, it is essential to establish efficient transduction. To date, targeted transduction of the photoreceptor-like cells of retinal organoids with adeno-associated virus (AAV) vectors has had varied degrees of success, which we have looked to improve in this study. Methods Retinal organoids were differentiated from iPSCs of healthy donors and transduced with reporter AAV containing a CAG.GFP, CAG.RFP, GRK1.GFP, or EFS.GFP transgene. Capsid variants assessed were AAV5, AAV2 7m8, AAV2 quad mutant, AAV2 Y444F, and AAV8 Y733F. At 27 days post-transduction, retinal organoids were assessed for reporter expression and viability. Results The short intron-less elongation factor 1 alpha (EFS) promoter provided minimal reporter expression, whereas vectors containing the CAG promoter enabled transduction in 1% to 37% of cells depending on the AAV serotype; the AAV2 quad mutant (average 19.4%) and AAV2 7m8 (16.4%) outperformed AAV5 (12%) and AAV8 Y733F (2.1%). Reporter expression from rhodopsin kinase (GRK1) promoter transgenes occurred in ∼5% of cells regardless of the serotype. Positive co-localization with recoverin-expressing cells was achieved from all GRK1 vectors and the CAG AAV2 quad mutant variant. Treatment with the AAV vectors did not influence retinal organoid viability. Conclusions Reliable transduction of the photoreceptor-like cells of retinal organoids can be readily achieved. When using a CAG-driven transgene, transduction of a broad range of cell types is observed, and GRK1 transgenes provide a more restricted expression profile locating to the outer layer of photoreceptor-like cells of retinal organoids. Translational Relevance This study expands the AAV capsid and transgene options for preclinical testing of gene therapy in iPSC-derived human retinal organoids.
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Affiliation(s)
- Michelle E McClements
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, University of Oxford, and Oxford University Hospitals NHS Foundation Trust, NIHR Biomedical Research Centre, Oxford, UK
| | | | | | | | | | | | - Robert E MacLaren
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, University of Oxford, and Oxford University Hospitals NHS Foundation Trust, NIHR Biomedical Research Centre, Oxford, UK
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22
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Piotter E, McClements ME, MacLaren RE. The Scope of Pathogenic ABCA4 Mutations Targetable by CRISPR DNA Base Editing Systems—A Systematic Review. Front Genet 2022; 12:814131. [PMID: 35154257 PMCID: PMC8830518 DOI: 10.3389/fgene.2021.814131] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 12/14/2021] [Indexed: 12/26/2022] Open
Abstract
Stargardt macular dystrophy (STGD1) is the most common form of inherited childhood blindness worldwide and for which no current treatments exist. It is an autosomal recessive disease caused by mutations in ABCA4. To date, a variety of gene supplementation approaches have been tested to create a therapy, with some reaching clinical trials. New technologies, such as CRISPR-Cas based editing systems, provide an exciting frontier for addressing genetic disease by allowing targeted DNA or RNA base editing of pathogenic mutations. ABCA4 has ∼1,200 known pathogenic mutations, of which ∼63% are transition mutations amenable to this editing technology. In this report, we screened the known “pathogenic” and “likely pathogenic” mutations in ABCA4 from available data in gnomAD, Leiden Open Variation Database (LOVD), and ClinVar for potential PAM sites of relevant base editors, including Streptococcus pyogenes Cas (SpCas), Staphylococcus aureus Cas (SaCas), and the KKH variant of SaCas (Sa-KKH). Overall, of the mutations screened, 53% (ClinVar), 71% (LOVD), and 71% (gnomAD), were editable, pathogenic transition mutations, of which 35–47% had “ideal” PAM sites. Of these mutations, 16–20% occur within a range of multiple PAM sites, enabling a variety of editing strategies. Further, in relevant patient data looking at three cohorts from Germany, Denmark, and China, we find that 44–76% of patients, depending on the presence of complex alleles, have at least one transition mutation with a nearby SaCas, SpCas, or Sa-KKH PAM site, which would allow for potential DNA base editing as a treatment strategy. Given the complexity of the genetic landscape of Stargardt, these findings provide a clearer understanding of the potential for DNA base editing approaches to be applied as ABCA4 gene therapy strategies.
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Affiliation(s)
- Elena Piotter
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
- *Correspondence: Elena Piotter,
| | - Michelle E. McClements
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - Robert E. MacLaren
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
- Oxford Eye Hospital, Oxford University Hospitals NHS Trust and NIHR Biomedical Research Centre, Oxford, United Kingdom
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23
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Fenner BJ, Tan TE, Barathi AV, Tun SBB, Yeo SW, Tsai ASH, Lee SY, Cheung CMG, Chan CM, Mehta JS, Teo KYC. Gene-Based Therapeutics for Inherited Retinal Diseases. Front Genet 2022; 12:794805. [PMID: 35069693 PMCID: PMC8782148 DOI: 10.3389/fgene.2021.794805] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 12/14/2021] [Indexed: 12/14/2022] Open
Abstract
Inherited retinal diseases (IRDs) are a heterogenous group of orphan eye diseases that typically result from monogenic mutations and are considered attractive targets for gene-based therapeutics. Following the approval of an IRD gene replacement therapy for Leber's congenital amaurosis due to RPE65 mutations, there has been an intensive international research effort to identify the optimal gene therapy approaches for a range of IRDs and many are now undergoing clinical trials. In this review we explore therapeutic challenges posed by IRDs and review current and future approaches that may be applicable to different subsets of IRD mutations. Emphasis is placed on five distinct approaches to gene-based therapy that have potential to treat the full spectrum of IRDs: 1) gene replacement using adeno-associated virus (AAV) and nonviral delivery vectors, 2) genome editing via the CRISPR/Cas9 system, 3) RNA editing by endogenous and exogenous ADAR, 4) mRNA targeting with antisense oligonucleotides for gene knockdown and splicing modification, and 5) optogenetic approaches that aim to replace the function of native retinal photoreceptors by engineering other retinal cell types to become capable of phototransduction.
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Affiliation(s)
- Beau J Fenner
- Singapore National Eye Centre, Singapore, Singapore.,Singapore Eye Research Institute, Singapore, Singapore.,Duke-NUS Graduate Medical School, Ophthalmology and Visual Sciences Academic Clinical Programme, Singapore, Singapore
| | - Tien-En Tan
- Singapore National Eye Centre, Singapore, Singapore.,Singapore Eye Research Institute, Singapore, Singapore.,Duke-NUS Graduate Medical School, Ophthalmology and Visual Sciences Academic Clinical Programme, Singapore, Singapore
| | | | - Sai Bo Bo Tun
- Singapore Eye Research Institute, Singapore, Singapore
| | - Sia Wey Yeo
- Singapore Eye Research Institute, Singapore, Singapore
| | - Andrew S H Tsai
- Singapore National Eye Centre, Singapore, Singapore.,Singapore Eye Research Institute, Singapore, Singapore.,Duke-NUS Graduate Medical School, Ophthalmology and Visual Sciences Academic Clinical Programme, Singapore, Singapore
| | - Shu Yen Lee
- Singapore National Eye Centre, Singapore, Singapore.,Singapore Eye Research Institute, Singapore, Singapore.,Duke-NUS Graduate Medical School, Ophthalmology and Visual Sciences Academic Clinical Programme, Singapore, Singapore
| | - Chui Ming Gemmy Cheung
- Singapore National Eye Centre, Singapore, Singapore.,Singapore Eye Research Institute, Singapore, Singapore.,Duke-NUS Graduate Medical School, Ophthalmology and Visual Sciences Academic Clinical Programme, Singapore, Singapore
| | - Choi Mun Chan
- Singapore National Eye Centre, Singapore, Singapore.,Singapore Eye Research Institute, Singapore, Singapore.,Duke-NUS Graduate Medical School, Ophthalmology and Visual Sciences Academic Clinical Programme, Singapore, Singapore
| | - Jodhbir S Mehta
- Singapore National Eye Centre, Singapore, Singapore.,Singapore Eye Research Institute, Singapore, Singapore.,Duke-NUS Graduate Medical School, Ophthalmology and Visual Sciences Academic Clinical Programme, Singapore, Singapore.,School of Material Science and Engineering, Nanyang Technological University, Singapore, Singapore.,Yong Loo Lin School of Medicine, Department of Ophthalmology, National University of Singapore, Singapore, Singapore
| | - Kelvin Y C Teo
- Singapore National Eye Centre, Singapore, Singapore.,Singapore Eye Research Institute, Singapore, Singapore.,Duke-NUS Graduate Medical School, Ophthalmology and Visual Sciences Academic Clinical Programme, Singapore, Singapore
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24
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Xiao X, Ye L, Chen C, Zheng H, Yuan J. Clinical Observation and Genotype-Phenotype Analysis of ABCA4- Related Hereditary Retinal Degeneration before Gene Therapy. Curr Gene Ther 2022; 22:342-351. [PMID: 35170407 PMCID: PMC10495610 DOI: 10.2174/1566523222666220216101539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 12/09/2021] [Accepted: 12/10/2021] [Indexed: 11/22/2022]
Abstract
BACKGROUND Hereditary retinal degeneration (HRD) is an irreversible eye disease that results in blindness in severe cases. It is most commonly caused by variants in the ABCA4 gene. HRD presents a high degree of clinical and genetic heterogeneity. We determined genotypic and phenotypic correlations, in the natural course of clinical observation, of unrelated progenitors of HRD associated with ABCA4. OBJECTIVE To analyze the relationship between the phenotypes and genotypes of ABCA4 variants. METHODS A retrospective clinical study of five cases from the ophthalmology department of the People's Hospital of Wuhan University from January 2019 to October 2020 was conducted. We tested for ABCA4 variants in the probands. We performed eye tests, including the best-corrected visual acuity, super-wide fundus photography and spontaneous fluorescence photography, optical coherence tomography, and electrophysiological examination. RESULTS Disease-causing variants were identified in the ABCA4 genes of all patients. Among these, seven ABCA4 variants were novel. All patients were sporadic cases; only one patient had parents who were relatives, and the other four patients were offspring of unrelated parents. Two patients presented with Stargardt disease, mainly with macular lesions, two presented with retinitis pigmentosa (cone-rod type), and one presented with cone dystrophy. The visual acuity and visual field of the five patients showed varying degrees of deterioration and impairment. CONCLUSION The same ABCA4 mutation can lead to different clinical phenotypes, and there is variation in the degree of damage to vision, visual field, and electrophysiology among different clinical phenotypes. Clinicians must differentiate between and diagnose pathologies resulting from this mutation.
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Affiliation(s)
- Xuan Xiao
- Eye Center, Renmin Hospital of Wuhan University, Wuhan University, Hubei, Wuhan 430060, China
| | - Lin Ye
- Department of Eye Plastic and Lacrimal Diseases, Shenzhen Eye Hospital, Shenzhen, China
| | - Changzheng Chen
- Eye Center, Renmin Hospital of Wuhan University, Wuhan University, Hubei, Wuhan 430060, China
| | - Hongmei Zheng
- Eye Center, Renmin Hospital of Wuhan University, Wuhan University, Hubei, Wuhan 430060, China
| | - Jiajia Yuan
- Eye Center, Renmin Hospital of Wuhan University, Wuhan University, Hubei, Wuhan 430060, China
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25
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Girach A, Audo I, Birch DG, Huckfeldt RM, Lam BL, Leroy BP, Michaelides M, Russell SR, Sallum JM, Stingl K, Tsang SH, Yang P. RNA-based therapies in inherited retinal diseases. Ther Adv Ophthalmol 2022; 14:25158414221134602. [PMID: 36388727 PMCID: PMC9643766 DOI: 10.1177/25158414221134602] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 10/05/2022] [Indexed: 11/10/2023] Open
Abstract
Inherited retinal diseases (IRDs) are a genetically and phenotypically heterogeneous group of genetic eye disorders. There are more than 300 disease entities, and together this group of disorders affects millions of people globally and is a frequent cause of blindness or low-vision certification. However, each type is rare or ultra-rare. Characteristically, the impaired vision in IRDs is due to retinal photoreceptor dysfunction and loss resulting from mutation in a gene that codes for a retinal protein. Historically, IRDs have been considered incurable and individuals living with these blinding conditions could be offered only supportive care. However, the treatment landscape for IRDs is beginning to evolve. Progress is being made, driven by improvements in understanding of genotype-phenotype relationships, through advances in molecular genetic testing and retinal imaging. Alongside this expanding knowledge of IRDs, the current era of precision medicine is fueling a growth in targeted therapies. This has resulted in the first treatment for an IRD being approved. Several other therapies are currently in development in the IRD space, including RNA-based therapies, gene-based therapies (such as augmentation therapy and gene editing), cell therapy, visual prosthetics, and optogenetics. RNA-based therapies are a novel approach within precision medicine that have demonstrated success, particularly in rare diseases. Three antisense oligonucleotides (AONs) are currently in development for the treatment of specific IRD subtypes. These RNA-based therapies bring several key advantages in the setting of IRDs, and the potential to bring meaningful vision benefit to individuals living with inherited blinding disorders. This review will examine the increasing breadth and relevance of RNA-based therapies in clinical medicine, explore the key features that make AONs suitable for treating genetic eye diseases, and provide an overview of the three-leading investigational AONs in clinical trials.
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Affiliation(s)
- Aniz Girach
- ProQR Therapeutics, Zernikedreef 9, 2333 CK
Leiden, the Netherlands
| | - Isabelle Audo
- Centre Hospitalier National d’Ophtalmologie des
Quinze-Vingts, Centre de référence maladies rares REFERET and INSERM-DHOS
CIC 1423, CHNO des Quinze-Vingts, Paris, France
- Institute of Ophthalmology, University College
London, London, UK
- Sorbonne Université, INSERM, CNRS, Institut de
la Vision, Paris, France
| | | | - Rachel M. Huckfeldt
- Department of Ophthalmology, Harvard Medical
School, Massachusetts Eye and Ear Infirmary, Boston, MA, USA
| | - Byron L. Lam
- Bascom Palmer Eye Institute, University of
Miami Miller School of Medicine, Miami, FL, USA
| | - Bart P. Leroy
- Department of Ophthalmology & Center for
Medical Genetics, Ghent University Hospital & Ghent University, Ghent,
Belgium
- Division of Ophthalmology & Center for
Cellular & Molecular Therapeutics, The Children’s Hospital of
Philadelphia, Philadelphia, PA, USA
| | - Michel Michaelides
- UCL Institute of Ophthalmology, University
College London and Moorfields Eye Hospital, London, UK
| | - Stephen R. Russell
- The University of Iowa Institute for Vision
Research, University of Iowa, Iowa City, IA, USA
| | - Juliana M.F. Sallum
- Department of Ophthalmology, Universidade
Federal de São Paulo, São Paulo, Brazil
- Instituto de Genética Ocular, São Paulo,
Brazil
| | - Katarina Stingl
- Center for Ophthalmology, University Eye
Hospital, University of Tübingen, Tübingen, Germany
- Center for Rare Eye Diseases, University of
Tübingen, Tübingen, Germany
| | - Stephen H. Tsang
- Jonas Children’s Vision Care and Bernard and
Shirlee Brown Glaucoma Laboratory, Columbia Stem Cell Initiative, Vagelos
College of Physicians and Surgeons, Columbia University, New York, NY,
USA
- Edward S. Harkness Eye Institute, New
York-Presbyterian Hospital, New York, NY, USA
| | - Paul Yang
- Casey Eye Institute, Oregon Health &
Science University, Portland, OR, USA
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26
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Molday RS, Garces FA, Scortecci JF, Molday LL. Structure and function of ABCA4 and its role in the visual cycle and Stargardt macular degeneration. Prog Retin Eye Res 2021; 89:101036. [PMID: 34954332 DOI: 10.1016/j.preteyeres.2021.101036] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 12/07/2021] [Accepted: 12/13/2021] [Indexed: 12/17/2022]
Abstract
ABCA4 is a member of the superfamily of ATP-binding cassette (ABC) transporters that is preferentially localized along the rim region of rod and cone photoreceptor outer segment disc membranes. It uses the energy from ATP binding and hydrolysis to transport N-retinylidene-phosphatidylethanolamine (N-Ret-PE), the Schiff base adduct of retinal and phosphatidylethanolamine, from the lumen to the cytoplasmic leaflet of disc membranes. This ensures that all-trans-retinal and excess 11-cis-retinal are efficiently cleared from photoreceptor cells thereby preventing the accumulation of toxic retinoid compounds. Loss-of-function mutations in the gene encoding ABCA4 cause autosomal recessive Stargardt macular degeneration, also known as Stargardt disease (STGD1), and related autosomal recessive retinopathies characterized by impaired central vision and an accumulation of lipofuscin and bis-retinoid compounds. High resolution structures of ABCA4 in its substrate and nucleotide free state and containing bound N-Ret-PE or ATP have been determined by cryo-electron microscopy providing insight into the molecular architecture of ABCA4 and mechanisms underlying substrate recognition and conformational changes induced by ATP binding. The expression and functional characterization of a large number of disease-causing missense ABCA4 variants have been determined. These studies have shed light into the molecular mechanisms underlying Stargardt disease and a classification that reliably predicts the effect of a specific missense mutation on the severity of the disease. They also provide a framework for developing rational therapeutic treatments for ABCA4-associated diseases.
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Affiliation(s)
- Robert S Molday
- Department of Biochemistry & Molecular Biology, University of British Columbia, Vancouver, B.C., Canada; Department of Ophthalmology & Visual Sciences, University of British Columbia, Vancouver, B.C., Canada.
| | - Fabian A Garces
- Department of Biochemistry & Molecular Biology, University of British Columbia, Vancouver, B.C., Canada
| | | | - Laurie L Molday
- Department of Biochemistry & Molecular Biology, University of British Columbia, Vancouver, B.C., Canada
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27
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Aziz K, Swenor BK, Canner JK, Singh MS. The Direct Healthcare Cost of Stargardt Disease: A Claims-Based Analysis. Ophthalmic Epidemiol 2021; 28:533-539. [PMID: 33615979 PMCID: PMC11207193 DOI: 10.1080/09286586.2021.1883675] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 01/24/2021] [Accepted: 01/25/2021] [Indexed: 10/22/2022]
Abstract
Purpose: Stargardt disease (SD) is the most common juvenile macular degeneration and a leading cause of uncorrectable childhood blindness. The progressive and incurable nature of this chronic condition entails a long-term financial burden on affected individuals. The economic costs of SD have not been characterized in detail, so we aimed to estimate the direct healthcare cost of SD.Methods: Outpatient administrative claims data (2010-2014) for patients with SD were analyzed from the IBM® MarketScan® Commercial Claims and Encounters Database. Two comparison groups were selected: nonexudative age-related macular degeneration (AMD) and bilateral sensorineural hearing loss (SHL). Gross median payments per year of insurance coverage were calculated.Results: A total of 472,428 patients were analyzed (5,015 SD, 369,750 SHL and 97,663 AMD patients respectively). The payment per year of insurance coverage for SD (median: 105.58 USD, IQR: 50.53 USD-218.71 USD) was higher than that of SHL (median: 51.01 USD, IQR: 25.66 USD-121.66 USD, p < .001) and AMD (median: 76.20 USD, IQR: 38.00 USD-164.86 USD, p < .001). When adjusted for age, sex, year of first service, and type of benefit plan, the annual payment for SD was 47.83 USD higher than SHL (p < .001) and 17.34 USD higher than AMD (p < .001).Conclusions: There is a significant direct healthcare cost associated with SD. The annual per-patient cost of SD was higher than SHL, another condition that causes sensory impairment in people of all ages, and nonexudative AMD which causes a similar pattern of visual loss that typically begins later in life. The total lifetime per-patient cost of SD may exceed that of nonexudative AMD.
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Affiliation(s)
- Kanza Aziz
- Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Bonnielin K. Swenor
- Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Joseph K. Canner
- Johns Hopkins Surgery Center for Outcomes Research, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Mandeep S. Singh
- Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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28
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Amato A, Arrigo A, Aragona E, Manitto MP, Saladino A, Bandello F, Battaglia Parodi M. Gene Therapy in Inherited Retinal Diseases: An Update on Current State of the Art. Front Med (Lausanne) 2021; 8:750586. [PMID: 34722588 PMCID: PMC8553993 DOI: 10.3389/fmed.2021.750586] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 09/20/2021] [Indexed: 12/11/2022] Open
Abstract
Background: Gene therapy cannot be yet considered a far perspective, but a tangible therapeutic option in the field of retinal diseases. Although still confined in experimental settings, the preliminary results are promising and provide an overall scenario suggesting that we are not so far from the application of gene therapy in clinical settings. The main aim of this review is to provide a complete and updated overview of the current state of the art and of the future perspectives of gene therapy applied on retinal diseases. Methods: We carefully revised the entire literature to report all the relevant findings related to the experimental procedures and the future scenarios of gene therapy applied in retinal diseases. A clinical background and a detailed description of the genetic features of each retinal disease included are also reported. Results: The current literature strongly support the hope of gene therapy options developed for retinal diseases. Although being considered in advanced stages of investigation for some retinal diseases, such as choroideremia (CHM), retinitis pigmentosa (RP), and Leber's congenital amaurosis (LCA), gene therapy is still quite far from a tangible application in clinical practice for other retinal diseases. Conclusions: Gene therapy is an extremely promising therapeutic tool for retinal diseases. The experimental data reported in this review offer a strong hope that gene therapy will be effectively available in clinical practice in the next years.
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Affiliation(s)
- Alessia Amato
- Department of Ophthalmology, Scientific Institute San Raffaele Hospital, Milan, Italy
| | - Alessandro Arrigo
- Department of Ophthalmology, Scientific Institute San Raffaele Hospital, Milan, Italy
| | - Emanuela Aragona
- Department of Ophthalmology, Scientific Institute San Raffaele Hospital, Milan, Italy
| | - Maria Pia Manitto
- Department of Ophthalmology, Scientific Institute San Raffaele Hospital, Milan, Italy
| | - Andrea Saladino
- Department of Ophthalmology, Scientific Institute San Raffaele Hospital, Milan, Italy
| | - Francesco Bandello
- Department of Ophthalmology, Scientific Institute San Raffaele Hospital, Milan, Italy
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29
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Cronin T, Croyal M, Provost N, Ducloyer JB, Mendes-Madeira A, Libeau L, Morival C, Toublanc E, Audrain C, Isiegas C, Pichard V, Adjali O. Effect of retinol dehydrogenase gene transfer in a novel rat model of Stargardt disease. FASEB J 2021; 35:e21934. [PMID: 34599778 DOI: 10.1096/fj.202002525rrr] [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: 11/30/2020] [Revised: 08/25/2021] [Accepted: 09/03/2021] [Indexed: 11/11/2022]
Abstract
Dysfunction of the ATPase-binding Cassette Transporter protein (ABCA4) can lead to early onset macular degeneration, in particular to Stargardt disease. To enable translational research into this form of blindness, we evaluated the effect of Cas9-induced disruptions of the ABCA4 gene to potentially generate new transgenic rat models of the disease. We show that deletion of the short exon preceding the second nucleotide-binding domain is sufficient to drastically knock down protein levels and results in accumulation of retinoid dimers similar to that associated with Stargardt disease. Overexpression of the retinol dehydrogenase enzymes RDH8 and RDH12 can to a limited extent offset the increase in the bisretinoid levels in the Abca4Ex42-/ - KO rats possibly by restricting the time window in which retinal can dimerize before being reduced to retinol. However, in vivo imaging shows that overexpression of RDH8 can induce retinal degeneration. This may be due to the depletion in the outer segment of the cofactor NADPH, needed for RDH function. The translational potential of RDH therapy as well as other Stargardt disease therapies can be tested using the Abca4 knockdown rat model.
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Affiliation(s)
- T Cronin
- Université de Nantes, CHU de Nantes, INSERM UMR 1089, Translational Gene Therapy for Genetic Diseases, Nantes, France
| | | | - N Provost
- Université de Nantes, CHU de Nantes, INSERM UMR 1089, Translational Gene Therapy for Genetic Diseases, Nantes, France
| | - J B Ducloyer
- Department of Ophthalmology, University Hospital of Nantes, CHU de Nantes, Nantes, France
| | - A Mendes-Madeira
- Université de Nantes, CHU de Nantes, INSERM UMR 1089, Translational Gene Therapy for Genetic Diseases, Nantes, France
| | - L Libeau
- Université de Nantes, CHU de Nantes, INSERM UMR 1089, Translational Gene Therapy for Genetic Diseases, Nantes, France
| | - C Morival
- Université de Nantes, CHU de Nantes, INSERM UMR 1089, Translational Gene Therapy for Genetic Diseases, Nantes, France
| | - E Toublanc
- Université de Nantes, CHU de Nantes, INSERM UMR 1089, Translational Gene Therapy for Genetic Diseases, Nantes, France
| | - C Audrain
- Université de Nantes, CHU de Nantes, INSERM UMR 1089, Translational Gene Therapy for Genetic Diseases, Nantes, France
| | - C Isiegas
- Université de Nantes, CHU de Nantes, INSERM UMR 1089, Translational Gene Therapy for Genetic Diseases, Nantes, France
| | - V Pichard
- Université de Nantes, CHU de Nantes, INSERM UMR 1089, Translational Gene Therapy for Genetic Diseases, Nantes, France
| | - O Adjali
- Université de Nantes, CHU de Nantes, INSERM UMR 1089, Translational Gene Therapy for Genetic Diseases, Nantes, France
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30
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31
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Massengill MT, Lewin AS. Gene Therapy for Rhodopsin-associated Autosomal Dominant Retinitis Pigmentosa. Int Ophthalmol Clin 2021; 61:79-96. [PMID: 34584046 PMCID: PMC8478325 DOI: 10.1097/iio.0000000000000383] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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32
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Nuzbrokh Y, Ragi SD, Tsang SH. Gene therapy for inherited retinal diseases. ANNALS OF TRANSLATIONAL MEDICINE 2021; 9:1278. [PMID: 34532415 PMCID: PMC8421966 DOI: 10.21037/atm-20-4726] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 11/04/2020] [Indexed: 01/04/2023]
Abstract
Inherited retinal diseases (IRDs) are a genetically variable collection of devastating disorders that lead to significant visual impairment. Advances in genetic characterization over the past two decades have allowed identification of over 260 causative mutations associated with inherited retinal disorders. Thought to be incurable, gene supplementation therapy offers great promise in treating various forms of these blinding conditions. In gene replacement therapy, a disease-causing gene is replaced with a functional copy of the gene. These therapies are designed to slow disease progression and hopefully restore visual function. Gene therapies are typically delivered to target retinal cells by subretinal (SR) or intravitreal (IVT) injection. The historic Food and Drug Administration (FDA) approval of voretigene neparvovec for RPE65-associated Leber's congenital amaurosis (LCA) spurred tremendous optimism surrounding retinal gene therapy for various other monogenic IRDs. Novel disease-causing mutations continue to be discovered annually, and targeted genetic therapy is now under development in clinical and preclinical models for many IRDs. Numerous clinical trials for other IRDs are ongoing or have recently completed. Disorders being targeted for genetic therapy include retinitis pigmentosa (RP), choroideremia (CHM), achromatopsia (ACHM), Leber's hereditary optic neuropathy, usher syndrome (USH), X-linked retinoschisis, and Stargardt disease. Here, we provide an update of completed, ongoing, and planned clinical trials using gene supplementation strategies for retinal degenerative disorders.
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Affiliation(s)
- Yan Nuzbrokh
- Department of Ophthalmology, Edward S. Harkness Eye Institute, Columbia University Irving Medical Center, New York, NY, USA.,Jonas Children's Vision Care, New York, NY, USA.,Renaissance School of Medicine at Stony Brook University, Stony Brook, New York, NY, USA
| | - Sara D Ragi
- Department of Ophthalmology, Edward S. Harkness Eye Institute, Columbia University Irving Medical Center, New York, NY, USA.,Jonas Children's Vision Care, New York, NY, USA
| | - Stephen H Tsang
- Department of Ophthalmology, Edward S. Harkness Eye Institute, Columbia University Irving Medical Center, New York, NY, USA.,Jonas Children's Vision Care, New York, NY, USA.,Department of Pathology & Cell Biology, Columbia University Irving Medical Center, New York, NY, USA
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33
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Abstract
The beginning of the twenty-first century was marked by the innovative use of pharmacochemical interventions, which have since expanded to include gene-based molecular therapies. For years, treatment has focused on tackling the pathophysiology of monogenic orphan diseases, and one of the first applications of these novel genome editing technologies was the treatment of rare inherited retinal dystrophies. In this review, we present recent, ongoing, and future gene therapy-based treatment trials for choroideremia, X-linked retinitis pigmentosa, Stargardt disease, and age-related macular degeneration. As these trials pave the way toward halting the progression of such devastating diseases, we will begin to see the exciting development of newer, cutting-edge strategies including base editing and prime editing, ushering in a new era of precision medicine.
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Affiliation(s)
- Sarah R Levi
- Jonas Children's Vision Care, Department of Ophthalmology, New York-Presbyterian Hospital, New York, New York 10032, USA; , , ,
| | - Joseph Ryu
- Jonas Children's Vision Care, Department of Ophthalmology, New York-Presbyterian Hospital, New York, New York 10032, USA; , , ,
| | - Pei-Kang Liu
- Jonas Children's Vision Care, Department of Ophthalmology, New York-Presbyterian Hospital, New York, New York 10032, USA; , , , .,Department of Ophthalmology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung 80708, Taiwan.,School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
| | - Stephen H Tsang
- Jonas Children's Vision Care, Department of Ophthalmology, New York-Presbyterian Hospital, New York, New York 10032, USA; , , , .,Department of Pathology & Cell Biology, Columbia Stem Cell Initiative, New York, New York 10032, USA
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Al-Khuzaei S, Broadgate S, Foster CR, Shah M, Yu J, Downes SM, Halford S. An Overview of the Genetics of ABCA4 Retinopathies, an Evolving Story. Genes (Basel) 2021; 12:1241. [PMID: 34440414 PMCID: PMC8392661 DOI: 10.3390/genes12081241] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 08/09/2021] [Accepted: 08/10/2021] [Indexed: 11/16/2022] Open
Abstract
Stargardt disease (STGD1) and ABCA4 retinopathies (ABCA4R) are caused by pathogenic variants in the ABCA4 gene inherited in an autosomal recessive manner. The gene encodes an importer flippase protein that prevents the build-up of vitamin A derivatives that are toxic to the RPE. Diagnosing ABCA4R is complex due to its phenotypic variability and the presence of other inherited retinal dystrophy phenocopies. ABCA4 is a large gene, comprising 50 exons; to date > 2000 variants have been described. These include missense, nonsense, splicing, structural, and deep intronic variants. Missense variants account for the majority of variants in ABCA4. However, in a significant proportion of patients with an ABCA4R phenotype, a second variant in ABCA4 is not identified. This could be due to the presence of yet unknown variants, or hypomorphic alleles being incorrectly classified as benign, or the possibility that the disease is caused by a variant in another gene. This underlines the importance of accurate genetic testing. The pathogenicity of novel variants can be predicted using in silico programs, but these rely on databases that are not ethnically diverse, thus highlighting the need for studies in differing populations. Functional studies in vitro are useful towards assessing protein function but do not directly measure the flippase activity. Obtaining an accurate molecular diagnosis is becoming increasingly more important as targeted therapeutic options become available; these include pharmacological, gene-based, and cell replacement-based therapies. The aim of this review is to provide an update on the current status of genotyping in ABCA4 and the status of the therapeutic approaches being investigated.
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Affiliation(s)
- Saoud Al-Khuzaei
- Oxford Eye Hospital, John Radcliffe Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, UK; (S.A.-K.); (M.S.)
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neuroscience, University of Oxford, Level 6 John Radcliffe Hospital, Headley Way, Oxford OX3 9DU, UK; (S.B.); (J.Y.)
| | - Suzanne Broadgate
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neuroscience, University of Oxford, Level 6 John Radcliffe Hospital, Headley Way, Oxford OX3 9DU, UK; (S.B.); (J.Y.)
| | | | - Mital Shah
- Oxford Eye Hospital, John Radcliffe Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, UK; (S.A.-K.); (M.S.)
| | - Jing Yu
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neuroscience, University of Oxford, Level 6 John Radcliffe Hospital, Headley Way, Oxford OX3 9DU, UK; (S.B.); (J.Y.)
| | - Susan M. Downes
- Oxford Eye Hospital, John Radcliffe Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, UK; (S.A.-K.); (M.S.)
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neuroscience, University of Oxford, Level 6 John Radcliffe Hospital, Headley Way, Oxford OX3 9DU, UK; (S.B.); (J.Y.)
| | - Stephanie Halford
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neuroscience, University of Oxford, Level 6 John Radcliffe Hospital, Headley Way, Oxford OX3 9DU, UK; (S.B.); (J.Y.)
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Piotter E, McClements ME, MacLaren RE. Therapy Approaches for Stargardt Disease. Biomolecules 2021; 11:1179. [PMID: 34439845 PMCID: PMC8393614 DOI: 10.3390/biom11081179] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 07/27/2021] [Accepted: 08/05/2021] [Indexed: 12/14/2022] Open
Abstract
Despite being the most prevalent cause of inherited blindness in children, Stargardt disease is yet to achieve the same clinical trial success as has been achieved for other inherited retinal diseases. With an early age of onset and continual progression of disease over the life course of an individual, Stargardt disease appears to lend itself to therapeutic intervention. However, the aetiology provides issues not encountered with the likes of choroideremia and X-linked retinitis pigmentosa and this has led to a spectrum of treatment strategies that approach the problem from different aspects. These include therapeutics ranging from small molecules and anti-sense oligonucleotides to viral gene supplementation and cell replacement. The advancing development of CRISPR-based molecular tools is also likely to contribute to future therapies by way of genome editing. In this we review, we consider the most recent pre-clinical and clinical trial data relating to the different strategies being applied to the problem of generating a treatment for the large cohort of Stargardt disease patients worldwide.
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Affiliation(s)
- Elena Piotter
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK; (E.P.); (M.E.M.)
- Oxford University Hospitals NHS Foundation Trust NIHR Biomedical Research Centre, Oxford OX3 9DU, UK
| | - Michelle E McClements
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK; (E.P.); (M.E.M.)
- Oxford University Hospitals NHS Foundation Trust NIHR Biomedical Research Centre, Oxford OX3 9DU, UK
| | - Robert E MacLaren
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK; (E.P.); (M.E.M.)
- Oxford University Hospitals NHS Foundation Trust NIHR Biomedical Research Centre, Oxford OX3 9DU, UK
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McClements ME, Butt A, Piotter E, Peddle CF, MacLaren RE. An analysis of the Kozak consensus in retinal genes and its relevance to gene therapy. Mol Vis 2021; 27:233-242. [PMID: 34012226 PMCID: PMC8116250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 05/06/2021] [Indexed: 11/24/2022] Open
Abstract
PURPOSE The classic Kozak consensus is a critical genetic element included in gene therapy transgenes to encourage the translation of the therapeutic coding sequence. Despite optimizations of other transgene elements, the Kozak consensus has not yet been considered for potential tissue-specific sequence refinement. We screened the -9 to -1 region relative to the AUG start codon of retina-specific genes to identify whether a Kozak consensus that is different from the classic sequence may be more appropriate for inclusion in gene therapy transgenes that treat inherited retinal disease. METHODS Sequences for 135 genes known to cause nonsyndromic inherited retinal disease were extracted from the NCBI database, and the -9 to -1 nucleotides were compared. This panel was then refined to 75 genes with specific retinal functions, for which the -9 to -1 nucleotides were placed in front of a GFP transcript sequence and RNAfold predictions performed. These were compared with a GFP sequence with the classic Kozak consensus (GCCGCCACC), and sequences from retinal genes with minimum free energy (MFE) predictions greater than the reference sequence were selected to generate an optimized Kozak consensus sequence. The original Kozak consensus and the refined retina Kozak consensus were placed upstream of the Renilla luciferase coding sequence, which were used to transfect retinoblastoma cell lines Y-79 and WERI-RB-1 and HEK 293T/17 cells. RESULTS The nucleotide frequencies of the original panel of genes were determined to be comparable to the classic Kozak consensus. RNAfold analysis of a GFP transcript with the classic Kozak sequence in the 5' untranslated region (UTR) generated an MFE prediction of -503.3 kcal/mol. RNAfold analysis was then performed with a GFP transcript containing each -9 to -1 Kozak sequence of 75 retinal genes. Thirty-eight of the 75 genes provided a greater MFE value than -503.3 kcal/mol and exhibited an absence of stable secondary structures before the AUG codon. The -9 to -1 nucleotide frequencies of these genes identified a Kozak consensus of ACCGAGACC, differing from the classic Kozak consensus at positions -9, -5, and -4. Applying this sequence to the GFP transcript increased the MFE prediction to -500.1 kcal/mol. The newly identified retina Kozak sequence was also applied to Renilla luciferase plus the REP1 and RPGR transcripts used in current clinical trials. In all examples, the predicted transcript MFE score increased when compared with the current transcript sequences containing classic Kozak consensus sequences. In vitro transfections identified a 7%-9% increase in Renilla activity when incorporating the optimized Kozak sequence. CONCLUSIONS The Kozak consensus is a critical element of eukaryotic genes; therefore, it is a required feature of gene therapy transgenes. To date, the classic sequence of GCCRCC (-6 to -1) has typically been incorporated in gene therapy transgenes, but the analysis described here suggests that, for vectors targeting the retina, using a Kozak consensus derived from retinal genes can provide increased expression of the target product.
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Camp DA, Gemayel MC, Ciulla TA. Understanding the genetic pathology of Stargardt disease: a review of current findings and challenges. Expert Opin Orphan Drugs 2021. [DOI: 10.1080/21678707.2021.1898373] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- David A. Camp
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Michael C. Gemayel
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Thomas A. Ciulla
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, IN, USA
- Retina Service, Midwest Eye Institute, Indianapolis, IN, USA
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Müller PL, Gliem M, McGuinnes M, Birtel J, Holz FG, Charbel Issa P. Quantitative Fundus Autofluorescence in ABCA4-Related Retinopathy -Functional Relevance and Genotype-Phenotype Correlation. Am J Ophthalmol 2021; 222:340-350. [PMID: 32891696 DOI: 10.1016/j.ajo.2020.08.042] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Revised: 08/25/2020] [Accepted: 08/25/2020] [Indexed: 02/05/2023]
Abstract
PURPOSE To investigate lipofuscin-related quantitative autofluorescence measures and their association with demographic characteristics, retinal structure, retinal function and genotype in ABCA4-related retinopathy (Stargardt disease 1). DESIGN Cross-sectional study with age-matched healthy control subjects. METHODS A total of 77 patients with ABCA4-related retinopathy and 110 control subjects underwent quantitative fundus autofluorescence (qAF) imaging using a confocal scanning laser ophthalmoscope equipped with an internal fluorescent reference to measure qAF as surrogate for lipofuscin accumulation. Measures of qAF were correlated with demographic characteristics, structural alterations on optical coherence tomography and fundus autofluorescence imaging, retinal function assessed by full-field electroretinography (ERG) and fundus-controlled perimetry, and genotype. RESULTS Most patients (76.6%) had qAF levels >95% prediction interval of the age-related control group, with best discrimination between cases and control subjects in younger patients. Reduced discrimination based on qAF measures was associated with mild disease, more advanced disease with dark flecks, or older age because of the physiological age-related increase in qAF and a ceiling effect in patients. Nullizygous patients presented with high qAF levels earlier in life compared with those with at least 1 milder ABCA4 variant. Within the sectors of qAF measurements, at approximately 7-9° eccentricity, increased qAF without flecks or with only bright flecks was associated with topographically related preserved retinal thickness and fundus-controlled perimetry results, and with normal full-field ERG recordings. All 3 parameters were increasingly abnormal with the development of dark flecks and decreasing qAF. CONCLUSIONS The accumulation of lipofuscin depends on the severity of ABCA4 variants, precedes other structural changes, and may remain without clinically relevant effect on retinal function.
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Kantor A, McClements ME, Peddle CF, Fry LE, Salman A, Cehajic-Kapetanovic J, Xue K, MacLaren RE. CRISPR genome engineering for retinal diseases. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2021; 182:29-79. [PMID: 34175046 DOI: 10.1016/bs.pmbts.2021.01.024] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Novel gene therapy treatments for inherited retinal diseases have been at the forefront of translational medicine over the past couple of decades. Since the discovery of CRISPR mechanisms and their potential application for the treatment of inherited human conditions, it seemed inevitable that advances would soon be made using retinal models of disease. The development of CRISPR technology for gene therapy and its increasing potential to selectively target disease-causing nucleotide changes has been rapid. In this chapter, we discuss the currently available CRISPR toolkit and how it has been and can be applied in the future for the treatment of inherited retinal diseases. These blinding conditions have until now had limited opportunity for successful therapeutic intervention, but the discovery of CRISPR has created new hope of achieving such, as we discuss within this chapter.
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Affiliation(s)
- Ariel Kantor
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, United Kingdom.
| | - Michelle E McClements
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, United Kingdom
| | - Caroline F Peddle
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, United Kingdom
| | - Lewis E Fry
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, United Kingdom; Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
| | - Ahmed Salman
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, United Kingdom
| | - Jasmina Cehajic-Kapetanovic
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, United Kingdom; Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
| | - Kanmin Xue
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, United Kingdom; Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
| | - Robert E MacLaren
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, United Kingdom; Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
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Al-Khuzaei S, Shah M, Foster CR, Yu J, Broadgate S, Halford S, Downes SM. The role of multimodal imaging and vision function testing in ABCA4-related retinopathies and their relevance to future therapeutic interventions. Ther Adv Ophthalmol 2021; 13:25158414211056384. [PMID: 34988368 PMCID: PMC8721514 DOI: 10.1177/25158414211056384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Accepted: 10/08/2021] [Indexed: 11/16/2022] Open
Abstract
The aim of this review article is to describe the specific features of Stargardt disease and ABCA4 retinopathies (ABCA4R) using multimodal imaging and functional testing and to highlight their relevance to potential therapeutic interventions. Standardised measures of tissue loss, tissue function and rate of change over time using formal structured deep phenotyping in Stargardt disease and ABCA4R are key in diagnosis, and prognosis as well as when selecting cohorts for therapeutic intervention. In addition, a meticulous documentation of natural history will be invaluable in the future to compare treated with untreated retinas. Despite the familiarity with the term Stargardt disease, this eponymous classification alone is unhelpful when evaluating ABCA4R, as the ABCA4 gene is associated with a number of phenotypes, and a range of severity. Multimodal imaging, psychophysical and electrophysiologic measurements are necessary in diagnosing and characterising these differing retinopathies. A wide range of retinal dystrophy phenotypes are seen in association with ABCA4 mutations. In this article, these will be referred to as ABCA4R. These different phenotypes and the existence of phenocopies present a significant challenge to the clinician. Careful phenotypic characterisation coupled with the genotype enables the clinician to provide an accurate diagnosis, associated inheritance pattern and information regarding prognosis and management. This is particularly relevant now for recruiting to therapeutic trials, and in the future when therapies become available. The importance of accurate genotype-phenotype correlation studies cannot be overemphasised. This approach together with segregation studies can be vital in the identification of causal mutations when variants in more than one gene are being considered as possible. In this article, we give an overview of the current imaging, psychophysical and electrophysiological investigations, as well as current therapeutic research trials for retinopathies associated with the ABCA4 gene.
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Affiliation(s)
- Saoud Al-Khuzaei
- Oxford Eye Hospital, John Radcliffe Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Mital Shah
- Oxford Eye Hospital, John Radcliffe Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | | | | | | | - Stephanie Halford
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Susan M. Downes
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Level 6 John Radcliffe Hospital, Headley Way, Oxford OX3 9DU, UK
- Oxford Eye Hospital, John Radcliffe Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
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Kansara VS, Cooper M, Sesenoglu-Laird O, Muya L, Moen R, Ciulla TA. Suprachoroidally Delivered DNA Nanoparticles Transfect Retina and Retinal Pigment Epithelium/Choroid in Rabbits. Transl Vis Sci Technol 2020; 9:21. [PMID: 33364076 PMCID: PMC7745627 DOI: 10.1167/tvst.9.13.21] [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: 07/24/2020] [Accepted: 10/16/2020] [Indexed: 01/04/2023] Open
Abstract
Purpose This study evaluated ocular tolerability and transfectability of nonviral DNA nanoparticles (DNPs) after microneedle-based suprachoroidal (SC) administration, in comparison to subretinal (SR) administration. Methods The DNPs consisted of a single copy of plasmid DNA with a polyubiquitin C/luciferase transcriptional cassette compacted with 10 kDa PEG-substituted lysine 30-mer peptides (CK30PEG10k). New Zealand White rabbits (n = 4 per group) received a unilateral SC injection (0.1 mL via a microneedle technique) of ellipsoid-shaped DNPs, rod-shaped DNPs, or saline (negative control). A cohort of rabbits (n = 4) also received a single unilateral SR injection (0.05 mL via a transvitreal approach) of rod-shaped DNPs. At day 7, luciferase activity was measured in the retina and retinal pigment epithelium (RPE)–choroid via bioluminescence assay. A cohort of rabbits received a SC injection of analogous DNPs to assess spread of DNP injectate in the suprachoroidal space (SCS) via optical coherent tomography and histology. Results Suprachoroidal injection of DNPs resulted in reversible opening of the SCS circumferentially and posteriorly and was generally well tolerated, with no significant ocular examination score changes, intraocular pressure abnormalities, or changes in electroretinography amplitudes on day 7 compared to the baseline. High luciferase activity was observed in the retina and RPE-choroid of eyes that received SC DNPs (rod and ellipsoid shape) and SR DNPs (rod shape) compared to controls. The mean luciferase activity in RPE-choroid and retina was comparable between SC and SR administrations. Transfection in the RPE-choroid was approximately 10-fold higher than in the retina after either SC or SR administration of DNPs. Conclusions Suprachoroidal and SR administration of DNPs resulted in comparable transfection of retina and RPE-choroid. Translational Relevance Suprachoroidal delivery of DNPs offers the potential to precisely target chorioretinal tissues while avoiding surgical risks associated with SR injection, and it may offer an office-based nonsurgical gene therapy option for the treatment of retinal diseases.
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Affiliation(s)
| | - Mark Cooper
- Copernicus Therapeutics, Inc., Cleveland, OH, USA
| | | | - Leroy Muya
- Clearside Biomedical, Inc., Alpharetta, GA, USA
| | - Robert Moen
- Copernicus Therapeutics, Inc., Cleveland, OH, USA
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Nuzbrokh Y, Kassotis AS, Ragi SD, Jauregui R, Tsang SH. Treatment-Emergent Adverse Events in Gene Therapy Trials for Inherited Retinal Diseases: A Narrative Review. Ophthalmol Ther 2020; 9:709-724. [PMID: 32740739 PMCID: PMC7708583 DOI: 10.1007/s40123-020-00287-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Indexed: 12/24/2022] Open
Abstract
Patient safety is a primary priority in the conduction of retinal gene therapy trials. An understanding of risk factors and mitigation strategies for post-procedure complications is crucial for the optimization of gene therapy clinical trial protocols. In this review, we synthesize the literature on ocular delivery methods, vector platforms, and treatment-emergent adverse effects in recent gene therapy clinical trials for inherited retinal diseases.
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Affiliation(s)
- Yan Nuzbrokh
- Department of Ophthalmology, Edward S. Harkness Eye Institute, Columbia University Irving Medical Center, New York, NY, USA
- Jonas Children's Vision Care, New York, NY, USA
- Renaissance School of Medicine, Stony Brook University, Stony Brook, NY, USA
| | - Alexis S Kassotis
- Department of Ophthalmology, Edward S. Harkness Eye Institute, Columbia University Irving Medical Center, New York, NY, USA
| | - Sara D Ragi
- Department of Ophthalmology, Edward S. Harkness Eye Institute, Columbia University Irving Medical Center, New York, NY, USA
- Jonas Children's Vision Care, New York, NY, USA
| | - Ruben Jauregui
- Department of Ophthalmology, Edward S. Harkness Eye Institute, Columbia University Irving Medical Center, New York, NY, USA
- Jonas Children's Vision Care, New York, NY, USA
| | - Stephen H Tsang
- Department of Ophthalmology, Edward S. Harkness Eye Institute, Columbia University Irving Medical Center, New York, NY, USA.
- Jonas Children's Vision Care, New York, NY, USA.
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, USA.
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Reisinger E. Dual-AAV delivery of large gene sequences to the inner ear. Hear Res 2020; 394:107857. [DOI: 10.1016/j.heares.2019.107857] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 11/22/2019] [Indexed: 01/06/2023]
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Xue K, MacLaren RE. Antisense oligonucleotide therapeutics in clinical trials for the treatment of inherited retinal diseases. Expert Opin Investig Drugs 2020; 29:1163-1170. [PMID: 32741234 DOI: 10.1080/13543784.2020.1804853] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
INTRODUCTION Antisense oligonucleotides (ASOs) represent a class of drugs which can be rationally designed to complement the coding or non-coding regions of target RNA transcripts. They could modulate pre-messenger RNA splicing, induce mRNA knockdown, or block translation of disease-causing genes, thereby slowing disease progression. The pharmacokinetics of intravitreal delivery may enable ASOs to be effective in the treatment of inherited retinal diseases. AREAS COVERED We review the current status of clinical trials of ASO therapies for inherited retinal diseases, which have demonstrated safety, viable durability, and early efficacy. Future applications are discussed in the context of alternative genetic approaches, including gene augmentation and gene editing. EXPERT OPINION Early efficacy data suggest that the splicing-modulating ASO, sepofarsen, is a promising treatment for Leber congenital amaurosis associated with the common c.2991+1655A>G mutation in CEP290. However, potential variability in clinical response to ASO-mediated correction of splicing defect on one allele in patients who are compound heterozygotes needs to be assessed. ASOs hold great therapeutic potential for numerous other inherited retinal diseases with common deep-intronic and dominant gain-of-function mutations. These would complement viral vector-mediated gene augmentation which is generally limited by the size of the transgene and to the treatment of recessive diseases.
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Affiliation(s)
- Kanmin Xue
- Wellcome Trust Clinical Research Career Development Fellow, Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford & Honorary Consultant Vitreoretinal Surgeon, Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust , Oxford, UK
| | - Robert E MacLaren
- Professor of Ophthalmology, Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford & Honorary Consultant Vitreoretinal Surgeon, Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust , Oxford, UK
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Kantor A, McClements ME, MacLaren RE. CRISPR-Cas9 DNA Base-Editing and Prime-Editing. Int J Mol Sci 2020; 21:E6240. [PMID: 32872311 PMCID: PMC7503568 DOI: 10.3390/ijms21176240] [Citation(s) in RCA: 168] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 08/18/2020] [Accepted: 08/25/2020] [Indexed: 12/15/2022] Open
Abstract
Many genetic diseases and undesirable traits are due to base-pair alterations in genomic DNA. Base-editing, the newest evolution of clustered regularly interspaced short palindromic repeats (CRISPR)-Cas-based technologies, can directly install point-mutations in cellular DNA without inducing a double-strand DNA break (DSB). Two classes of DNA base-editors have been described thus far, cytosine base-editors (CBEs) and adenine base-editors (ABEs). Recently, prime-editing (PE) has further expanded the CRISPR-base-edit toolkit to all twelve possible transition and transversion mutations, as well as small insertion or deletion mutations. Safe and efficient delivery of editing systems to target cells is one of the most paramount and challenging components for the therapeutic success of BEs. Due to its broad tropism, well-studied serotypes, and reduced immunogenicity, adeno-associated vector (AAV) has emerged as the leading platform for viral delivery of genome editing agents, including DNA-base-editors. In this review, we describe the development of various base-editors, assess their technical advantages and limitations, and discuss their therapeutic potential to treat debilitating human diseases.
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Affiliation(s)
- Ariel Kantor
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford OX3 9DU, UK; (M.E.M.); (R.E.M.)
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, UK
| | - Michelle E. McClements
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford OX3 9DU, UK; (M.E.M.); (R.E.M.)
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, UK
| | - Robert E. MacLaren
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford OX3 9DU, UK; (M.E.M.); (R.E.M.)
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, UK
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Cui XW, Ren JY, Gu YH, Li QF, Wang ZC. NF1, Neurofibromin and Gene Therapy: Prospects of Next-Generation Therapy. Curr Gene Ther 2020; 20:100-108. [PMID: 32767931 DOI: 10.2174/1566523220666200806111451] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 07/10/2020] [Accepted: 07/14/2020] [Indexed: 12/28/2022]
Abstract
Neurofibromatosis type 1 [NF1] is an autosomal dominant genetic disorder affecting multiple organs. NF1 is well known for its various clinical manifestations, including café-au-late macules, Lisch nodules, bone deformity and neurofibromas. However, there is no effective therapy for NF1. Current therapies are aimed at alleviating NF1 clinical symptoms but not curing the disease. By altering pathogenic genes, gene therapy regulates cell activities at the nucleotide level. In this review, we described the structure and functions of neurofibromin domains, including GAP-related domain [GRD], cysteine-serine rich domain [CSRD], leucine-rich domain [LRD] and C-terminal domain [CTD], which respectively alter downstream pathways. By transfecting isolated sequences of these domains, researchers can partially restore normal cell functions in neurofibroma cell lines. Furthermore, recombinant transgene sequences may be designed to encode truncated proteins, which is functional and easy to be packaged into viral vectors. In addition, the treatment effect of gene therapy is also determined by various factors such as the vectors selection, transgene packaging strategies and drug administration. We summarized multiple NF1 gene therapy strategies and discussed their feasibility from multiple angles. Different protein domains alter the function and downstream pathways of neurofibromin.
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Affiliation(s)
- Xi-Wei Cui
- Department of Plastic and Reconstructive Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
| | - Jie-Yi Ren
- Department of Plastic and Reconstructive Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
| | - Yi-Hui Gu
- Department of Plastic and Reconstructive Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
| | - Qing-Feng Li
- Department of Plastic and Reconstructive Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
| | - Zhi-Chao Wang
- Department of Plastic and Reconstructive Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
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Abstract
Retinal degenerations account for the majority of untreatable causes of blindness. Advances in gene delivery vectors, CRISPR/Cas9-based gene editing systems, and electronic engineering have led to a wide range of strategies for correcting visual loss. Here, we provide an overview of retinal gene therapy, gene editing, optogenetics and retinal prostheses using examples from recent clinical trials and pre-clinical studies.
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Affiliation(s)
- Kanmin Xue
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, and Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Robert E MacLaren
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, and Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
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48
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Fry LE, Peddle CF, Stevanovic M, Barnard AR, McClements ME, MacLaren RE. Promoter Orientation within an AAV-CRISPR Vector Affects Cas9 Expression and Gene Editing Efficiency. CRISPR J 2020; 3:276-283. [PMID: 32833533 PMCID: PMC7469699 DOI: 10.1089/crispr.2020.0021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Adeno-associated virus (AAV) vectors have been widely adopted for delivery of CRISPR-Cas components, especially for therapeutic gene editing. For a single vector system, both the Cas9 and guide RNA (gRNA) are encoded within a single transgene, usually from separate promoters. Careful design of this bi-cistronic construct is required due to the minimal packaging capacity of AAV. We investigated how placement of the U6 promoter expressing the gRNA on the reverse strand to SaCas9 driven by a cytomegalovirus promoter affected gene editing rates compared to placement on the forward strand. We show that orientation in the reverse direction reduces editing rates from an AAV vector due to reduced transcription of both SaCas9 and guide RNA. This effect was observed only following AAV transduction; it was not seen following plasmid transfection. These results have implications for the design of AAV-CRISPR vectors, and suggest that results from optimizing plasmid transgenes may not translate when delivered via AAV.
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Affiliation(s)
- Lewis E. Fry
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences and NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, United Kingdom
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
| | - Caroline F. Peddle
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences and NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, United Kingdom
| | - Marta Stevanovic
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences and NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, United Kingdom
| | - Alun R. Barnard
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences and NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, United Kingdom
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
| | - Michelle E. McClements
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences and NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, United Kingdom
| | - Robert E. MacLaren
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences and NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, United Kingdom
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
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49
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French LS, Mellough CB, Chen FK, Carvalho LS. A Review of Gene, Drug and Cell-Based Therapies for Usher Syndrome. Front Cell Neurosci 2020; 14:183. [PMID: 32733204 PMCID: PMC7363968 DOI: 10.3389/fncel.2020.00183] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Accepted: 05/28/2020] [Indexed: 12/12/2022] Open
Abstract
Usher syndrome is a genetic disorder causing neurosensory hearing loss and blindness from retinitis pigmentosa (RP). Adaptive techniques such as braille, digital and optical magnifiers, mobility training, cochlear implants, or other assistive listening devices are indispensable for reducing disability. However, there is currently no treatment to reduce or arrest sensory cell degeneration. There are several classes of treatments for Usher syndrome being investigated. The present article reviews the progress this research has made towards delivering commercial options for patients with Usher syndrome.
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Affiliation(s)
- Lucy S French
- Centre for Ophthalmology and Visual Sciences (incorporating Lions Eye Institute), The University of Western Australia, Nedlands, WA, Australia
| | - Carla B Mellough
- Centre for Ophthalmology and Visual Sciences (incorporating Lions Eye Institute), The University of Western Australia, Nedlands, WA, Australia
| | - Fred K Chen
- Centre for Ophthalmology and Visual Sciences (incorporating Lions Eye Institute), The University of Western Australia, Nedlands, WA, Australia.,Department of Ophthalmology, Royal Perth Hospital, Perth, WA, Australia.,Department of Ophthalmology, Perth Children's Hospital, Nedlands, WA, Australia
| | - Livia S Carvalho
- Centre for Ophthalmology and Visual Sciences (incorporating Lions Eye Institute), The University of Western Australia, Nedlands, WA, Australia
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50
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Retinal gene therapy: an eye-opener of the 21st century. Gene Ther 2020; 28:209-216. [PMID: 32561864 DOI: 10.1038/s41434-020-0168-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 06/02/2020] [Accepted: 06/09/2020] [Indexed: 02/07/2023]
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