201
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Kiser PD, Golczak M, Maeda A, Palczewski K. Key enzymes of the retinoid (visual) cycle in vertebrate retina. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1821:137-51. [PMID: 21447403 DOI: 10.1016/j.bbalip.2011.03.005] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Revised: 03/08/2011] [Accepted: 03/22/2011] [Indexed: 12/11/2022]
Abstract
A major goal in vision research over the past few decades has been to understand the molecular details of retinoid processing within the retinoid (visual) cycle. This includes the consequences of side reactions that result from delayed all-trans-retinal clearance and condensation with phospholipids that characterize a variety of serious retinal diseases. Knowledge of the basic retinoid biochemistry involved in these diseases is essential for development of effective therapeutics. Photoisomerization of the 11-cis-retinal chromophore of rhodopsin triggers a complex set of metabolic transformations collectively termed phototransduction that ultimately lead to light perception. Continuity of vision depends on continuous conversion of all-trans-retinal back to the 11-cis-retinal isomer. This process takes place in a series of reactions known as the retinoid cycle, which occur in photoreceptor and RPE cells. All-trans-retinal, the initial substrate of this cycle, is a chemically reactive aldehyde that can form toxic conjugates with proteins and lipids. Therefore, much experimental effort has been devoted to elucidate molecular mechanisms of the retinoid cycle and all-trans-retinal-mediated retinal degeneration, resulting in delineation of many key steps involved in regenerating 11-cis-retinal. Three particularly important reactions are catalyzed by enzymes broadly classified as acyltransferases, short-chain dehydrogenases/reductases and carotenoid/retinoid isomerases/oxygenases. This article is part of a Special Issue entitled: Retinoid and Lipid Metabolism.
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Affiliation(s)
- Philip D Kiser
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH 44106-4965, USA
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202
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Qatarneh D, Mehta H, Lee V. Insight into Leber congenital amaurosis: potential for gene therapy. EXPERT REVIEW OF OPHTHALMOLOGY 2011. [DOI: 10.1586/eop.11.7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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203
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Sparrow JR, Hicks D, Hamel CP. The retinal pigment epithelium in health and disease. Curr Mol Med 2011; 10:802-23. [PMID: 21091424 DOI: 10.2174/156652410793937813] [Citation(s) in RCA: 417] [Impact Index Per Article: 32.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2010] [Accepted: 09/13/2010] [Indexed: 12/15/2022]
Abstract
Retinal pigment epithelial cells (RPE) constitute a simple layer of cuboidal cells that are strategically situated behind the photoreceptor (PR) cells. The inconspicuousness of this monolayer contrasts sharply with its importance [1]. The relationship between the RPE and PR cells is crucial to sight; this is evident from basic and clinical studies demonstrating that primary dysfunctioning of the RPE can result in visual cell death and blindness. RPE cells carry out many functions including the conversion and storage of retinoid, the phagocytosis of shed PR outer segment membrane, the absorption of scattered light, ion and fluid transport and RPE-PR apposition. The magnitude of the demands imposed on this single layer of cells in order to execute these tasks, will become apparent to the reader of this review as will the number of clinical disorders that take origin from these cells.
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Affiliation(s)
- J R Sparrow
- Department of Ophthalmology, Columbia University, New York, NY 10032, USA.
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204
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Fradot M, Busskamp V, Forster V, Cronin T, Léveillard T, Bennett J, Sahel JA, Roska B, Picaud S. Gene therapy in ophthalmology: validation on cultured retinal cells and explants from postmortem human eyes. Hum Gene Ther 2011; 22:587-93. [PMID: 21142470 DOI: 10.1089/hum.2010.157] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Gene therapy studies in primates can provide important information regarding vector tropism, specific cellular expression, biodistribution, and safety prior to clinical trials. In this study, we report the assessment of transduction efficiency of recombinant adeno-associated virus (rAAV) vectors using human postmortem retina. Transductions were performed using two in vitro models prepared from human tissue: dissociated cell cultures and retinal explants. These models were used to assess cellular tropism and selectivity of rAAV vectors encoding for fluorescent proteins under the control of different promoters. These promoters were a ubiquitous cytomegalovirus promoter and a cell type-specific promoter targeting expression in ON bipolar cells. The results demonstrate that this in vitro approach can limit the use of living primates for the validation of gene therapy in vision and ophthalmology.
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205
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Wang S, Liu P, Song L, Lu L, Zhang W, Wu Y. Adeno-associated virus (AAV) based gene therapy for eye diseases. Cell Tissue Bank 2011; 12:105-10. [DOI: 10.1007/s10561-011-9243-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2010] [Accepted: 02/04/2011] [Indexed: 12/27/2022]
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206
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Kostic C, Crippa SV, Pignat V, Bemelmans AP, Samardzija M, Grimm C, Wenzel A, Arsenijevic Y. Gene therapy regenerates protein expression in cone photoreceptors in Rpe65(R91W/R91W) mice. PLoS One 2011; 6:e16588. [PMID: 21304899 PMCID: PMC3033393 DOI: 10.1371/journal.pone.0016588] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2010] [Accepted: 12/21/2010] [Indexed: 12/22/2022] Open
Abstract
Cone photoreceptors mediate visual acuity under daylight conditions, so loss of cone-mediated central vision of course dramatically affects the quality of life of patients suffering from retinal degeneration. Therefore, promoting cone survival has become the goal of many ocular therapies and defining the stage of degeneration that still allows cell rescue is of prime importance. Using the Rpe65R91W/R91W mouse, which carries a mutation in the Rpe65 gene leading to progressive photoreceptor degeneration in both patients and mice, we defined stages of retinal degeneration that still allow cone rescue. We evaluated the therapeutic window within which cones can be rescued, using a subretinal injection of a lentiviral vector driving expression of RPE65 in the Rpe65R91W/R91W mice. Surprisingly, when applied to adult mice (1 month) this treatment not only stalls or slows cone degeneration but, actually, induces cone-specific protein expression that was previously absent. Before the intervention only part of the cones (40% of the number found in wild-type animals) in the Rpe65R91W/R91W mice expressed cone transducin (GNAT2); this fraction increased to 64% after treatment. Correct S-opsin localization is also recovered in the transduced region. In consequence these results represent an extended therapeutic window compared to the Rpe65-/- mice, implying that patients suffering from missense mutations might also benefit from a prolonged therapeutic window. Moreover, cones are not only rescued during the course of the degeneration, but can actually recover their initial status, meaning that a proportion of altered cones in chromophore deficiency-related disease can be rehabilitated even though they are severely affected.
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Affiliation(s)
- Corinne Kostic
- Unit of Gene Therapy and Stem Cell Biology, Jules-Gonin Eye Hospital, University of Lausanne, Lausanne, Switzerland.
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207
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Bramall AN, Wright AF, Jacobson SG, McInnes RR. The genomic, biochemical, and cellular responses of the retina in inherited photoreceptor degenerations and prospects for the treatment of these disorders. Annu Rev Neurosci 2011; 33:441-72. [PMID: 20572772 DOI: 10.1146/annurev-neuro-060909-153227] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The association of more than 140 genes with human photoreceptor degenerations, together with studies of animal models of these monogenic diseases, has provided great insight into their pathogenesis. Here we review the responses of the retina to photoreceptor mutations, including mechanisms of photoreceptor death. We discuss the roles of oxidative metabolism, mitochondrial reactive oxygen species, metabolic stress, protein misfolding, and defects in ciliary proteins, as well as the responses of Müller glia, microglia, and the retinal vasculature. Finally, we report on potential pharmacologic and biologic therapies, the critical role of histopathology as a prerequisite to treatment, and the exciting promise of gene therapy in animal models and in phase 1 trials in humans.
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Affiliation(s)
- Alexa N Bramall
- Programs in Genetics and Developmental Biology, The Research Institute, The Hospital for Sick Children, Toronto M5G1L7, Canada.
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208
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Fletcher EL, Jobling AI, Vessey KA, Luu C, Guymer RH, Baird PN. Animal models of retinal disease. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2011; 100:211-86. [PMID: 21377628 DOI: 10.1016/b978-0-12-384878-9.00006-6] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Diseases of the retina are the leading causes of blindness in the industrialized world. The recognition that animals develop retinal diseases with similar traits to humans has led to not only a dramatic improvement in our understanding of the pathogenesis of retinal disease but also provided a means for testing possible treatment regimes and successful gene therapy trials. With the advent of genetic and molecular biological tools, the association between specific gene mutations and retinal signs has been made. Animals carrying natural mutations usually in one gene now provide well-established models for a host of inherited retinal diseases, including retinitis pigmentosa, Leber congenital amaurosis, inherited macular degeneration, and optic nerve diseases. In addition, the development of transgenic technologies has provided a means by which to study the effects of these and novel induced mutations on retinal structure and function. Despite these advances, there is a paucity of suitable animal models for complex diseases, including age-related macular degeneration (AMD) and diabetic retinopathy, largely because these diseases are not caused by single gene defects, but involve complex genetics and/or exacerbation through environmental factors, epigenetic, or other modes of genetic influence. In this review, we outline in detail the available animal models for inherited retinal diseases and how this information has furthered our understanding of retinal diseases. We also examine how transgenic technologies have helped to develop our understanding of the role of isolated genes or pathways in complex diseases like AMD, diabetes, and glaucoma.
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Affiliation(s)
- Erica L Fletcher
- Department of Anatomy and Cell Biology, The University of Melbourne, Parkville, Victoria, Australia
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209
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Annear MJ, Bartoe JT, Barker SE, Smith AJ, Curran PG, Bainbridge JW, Ali RR, Petersen-Jones SM. Gene therapy in the second eye of RPE65-deficient dogs improves retinal function. Gene Ther 2011; 18:53-61. [PMID: 20703309 PMCID: PMC3381842 DOI: 10.1038/gt.2010.111] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Revised: 05/01/2010] [Accepted: 06/14/2010] [Indexed: 11/08/2022]
Abstract
The purpose of this study was to evaluate whether immune responses interfered with gene therapy rescue using subretinally delivered recombinant adeno-associated viral vector serotype 2 carrying the RPE65 cDNA gene driven by the human RPE65 promoter (rAAV2.hRPE65p.hRPE65) in the second eye of RPE65-/- dogs that had previously been treated in a similar manner in the other eye. Bilateral subretinal injection was performed in nine dogs with the second eye treated 85-180 days after the first. Electroretinography (ERG) and vision testing showed rescue in 16 of 18 treated eyes, with no significant difference between first and second treated eyes. A serum neutralizing antibody (NAb) response to rAAV2 was detected in all treated animals, but this did not prevent or reduce the effectiveness of rescue in the second treated eye. We conclude that successful rescue using subretinal rAAV2.hRPE65p.hRPE65 gene therapy in the second eye is not precluded by prior gene therapy in the contralateral eye of the RPE65-/- dog. This finding has important implications for the treatment of human LCA type II patients.
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Affiliation(s)
- MJ Annear
- Department of Small Animal Clinical Sciences, Michigan State University, East Lansing, MI, USA
| | - JT Bartoe
- Department of Small Animal Clinical Sciences, Michigan State University, East Lansing, MI, USA
| | - SE Barker
- Department of Genetics, UCL Institute of Ophthalmology, London, UK
| | - AJ Smith
- Department of Genetics, UCL Institute of Ophthalmology, London, UK
| | - PG Curran
- Center for Statistical Consulting, Michigan State University, East Lansing, MI, USA
| | - JW Bainbridge
- Department of Genetics, UCL Institute of Ophthalmology, London, UK
| | - RR Ali
- Department of Genetics, UCL Institute of Ophthalmology, London, UK
| | - SM Petersen-Jones
- Department of Small Animal Clinical Sciences, Michigan State University, East Lansing, MI, USA
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210
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Preclinical safety evaluation of AAV2-sFLT01- a gene therapy for age-related macular degeneration. Mol Ther 2010; 19:326-34. [PMID: 21119620 DOI: 10.1038/mt.2010.258] [Citation(s) in RCA: 132] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
AAV2-sFLT01 is a vector that expresses a modified soluble Flt1 receptor designed to neutralize the proangiogenic activities of vascular endothelial growth factor (VEGF) for treatment of age-related macular degeneration (AMD) via an intravitreal injection. Owing to minimal data available for the intravitreal route of administration for adeno-associated virus (AAV), we initiated a 12-month safety study of AAV2-sFLT01 administered intravitreally at doses of 2.4 × 10(9) vector genomes (vg) and 2.4 × 10(10) vg to cynomolgus monkeys. Expression of sFlt01 protein peaked at ~1-month postadministration and remained relatively constant for the remainder of the study. Electroretinograms, fluorescein angiograms, and tonometry were assessed every 3 months, with no test article-related findings observed in any group. Indirect ophthalmoscopy and slit lamp exams performed monthly revealed a mild to moderate but self-resolving vitreal inflammation in the high-dose group only, which follow-up studies suggest was directed against the AAV2 capsid. Histological evaluation revealed no structural changes in any part of the eye and occasional inflammatory cells in the trabecular meshwork, vitreous and retina in the high-dose group. Biodistribution analysis in rats and monkeys found only trace amounts of vector outside the injected eye. In summary, these studies found AAV2-sFLT01 to be well-tolerated, localized, and capable of long-term expression.
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211
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Mays LE, Wilson JM. The complex and evolving story of T cell activation to AAV vector-encoded transgene products. Mol Ther 2010; 19:16-27. [PMID: 21119617 DOI: 10.1038/mt.2010.250] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Original reports of adeno-associated virus (AAV) vector-mediated gene transfer to the muscle resulted in high-level β-galactosidase (β-gal) expression and the promise of a viral vector that was largely nonimmunogenic. Subsequent attempts to utilize these vectors for genetic vaccination, however, demonstrated that it was possible to activate cellular and humoral immunity to AAV-encoded antigens. These findings fueled years of investigation into factors impacting the immunogenicity of recombinant AAV-mediated gene delivery, including route of administration, dose, host species, capsid serotype, and transgene product. In cases where AAV vectors could avoid transgene-directed immunity, it became clear that mechanisms of tolerance were at work, varying between ignorance, anergy/deletion, or active suppression. Here, we follow the field of AAV gene therapy from inception, as investigators have worked to understand the delicate balance between AAV-mediated tolerance and the activation of immunity. This review discusses our current appreciation of AAV vector immunology, with a specific focus on the transgene-specific T cell response.
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Affiliation(s)
- Lauren E Mays
- Department of Pathology and Laboratory Medicine, Division of Transfusion Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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212
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Current concepts in the treatment of retinitis pigmentosa. J Ophthalmol 2010; 2011:753547. [PMID: 21048997 PMCID: PMC2964907 DOI: 10.1155/2011/753547] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2010] [Accepted: 09/16/2010] [Indexed: 12/11/2022] Open
Abstract
Inherited retinal degenerations, including retinitis pigmentosa (RP) and Leber congenital amaurosis (LCA), affect 1 in 4000 individuals in the general population. A majority of the genes which are mutated in these conditions are expressed in either photoreceptors or the retinal pigment epithelium (RPE). There is considerable variation in the clinical severity of these conditions; the most severe being autosomal recessive LCA, a heterogeneous retinal degenerative disease and the commonest cause of congenital blindness in children. Here, we discuss all the potential treatments that are now available for retinal degeneration. A number of therapeutic avenues are being explored based on our knowledge of the pathophysiology of retinal degeneration derived from research on animal models, including: gene therapy, antiapoptosis agents, neurotrophic factors, and dietary supplementation. Technological advances in retinal implant devices continue to provide the promise of vision for patients with end-stage disease.
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213
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Amado D, Mingozzi F, Hui D, Bennicelli JL, Wei Z, Chen Y, Bote E, Grant RL, Golden JA, Narfstrom K, Syed NA, Orlin SE, High KA, Maguire AM, Bennett J. Safety and efficacy of subretinal readministration of a viral vector in large animals to treat congenital blindness. Sci Transl Med 2010; 2:21ra16. [PMID: 20374996 DOI: 10.1126/scitranslmed.3000659] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Leber's congenital amaurosis (LCA) is a group of severe inherited retinal degenerations that are symptomatic in infancy and lead to total blindness in adulthood. Recent clinical trials using recombinant adeno-associated virus serotype 2 (rAAV2) successfully reversed blindness in patients with LCA caused by RPE65 mutations after one subretinal injection. However, it was unclear whether treatment of the second eye in the same manner would be safe and efficacious, given the potential for a complicating immune response after the first injection. Here, we evaluated the immunological and functional consequences of readministration of rAAV2-hRPE65v2 to the contralateral eye using large animal models. Neither RPE65-mutant (affected; RPE65(-/-)) nor unaffected animals developed antibodies against the transgene product, but all developed neutralizing antibodies against the AAV2 capsid in sera and intraocular fluid after subretinal injection. Cell-mediated immune responses were benign, with only 1 of 10 animals in the study developing a persistent T cell immune response to AAV2, a response that was mediated by CD4(+) T cells. Sequential bilateral injection caused minimal inflammation and improved visual function in affected animals. Thus, subretinal readministration of rAAV2 in animals is safe and effective, even in the setting of preexisting immunity to the vector, a parameter that has been used to exclude patients from gene therapy trials.
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Affiliation(s)
- Defne Amado
- F. M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA 19104, USA
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214
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Retinoids for treatment of retinal diseases. Trends Pharmacol Sci 2010; 31:284-95. [PMID: 20435355 DOI: 10.1016/j.tips.2010.03.001] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2010] [Revised: 03/10/2010] [Accepted: 03/11/2010] [Indexed: 12/31/2022]
Abstract
Knowledge about retinal photoreceptor signal transduction and the visual cycle required for normal eyesight has increased exponentially over the past decade. Substantial progress in human genetics has facilitated the identification of candidate genes and complex networks underlying inherited retinal diseases. Natural mutations in animal models that mimic human diseases have been characterized and advanced genetic manipulation can now be used to generate small mammalian models of human retinal diseases. Pharmacological repair of defective visual processes in animal models not only validates their involvement in vision, but also provides great promise for the development of improved therapies for millions who are progressing towards blindness or are almost completely robbed of their eyesight.
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215
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Komáromy AM. Day blind sheep and the importance of large animal disease models. Vet J 2010; 185:241-2. [DOI: 10.1016/j.tvjl.2009.07.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2009] [Accepted: 07/08/2009] [Indexed: 11/25/2022]
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216
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den Hollander AI, Black A, Bennett J, Cremers FPM. Lighting a candle in the dark: advances in genetics and gene therapy of recessive retinal dystrophies. J Clin Invest 2010; 120:3042-53. [PMID: 20811160 DOI: 10.1172/jci42258] [Citation(s) in RCA: 156] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Nonsyndromic recessive retinal dystrophies cause severe visual impairment due to the death of photoreceptor and retinal pigment epithelium cells. These diseases until recently have been considered to be incurable. Molecular genetic studies in the last two decades have revealed the underlying molecular causes in approximately two-thirds of patients. The mammalian eye has been at the forefront of therapeutic trials based on gene augmentation in humans with an early-onset nonsyndromic recessive retinal dystrophy due to mutations in the retinal pigment epithelium-specific protein 65kDa (RPE65) gene. Tremendous challenges still lie ahead to extrapolate these studies to other retinal disease-causing genes, as human gene augmentation studies require testing in animal models for each individual gene and sufficiently large patient cohorts for clinical trials remain to be identified through cost-effective mutation screening protocols.
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Affiliation(s)
- Anneke I den Hollander
- Department of Ophthalmology, Radboud University Nijmegen Medical Centre, Nijmegen, Netherlands
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217
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Goldstein O, Mezey JG, Boyko AR, Gao C, Wang W, Bustamante CD, Anguish LJ, Jordan JA, Pearce-Kelling SE, Aguirre GD, Acland GM. An ADAM9 mutation in canine cone-rod dystrophy 3 establishes homology with human cone-rod dystrophy 9. Mol Vis 2010; 16:1549-69. [PMID: 20806078 PMCID: PMC2925905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2010] [Accepted: 08/06/2010] [Indexed: 11/17/2022] Open
Abstract
PURPOSE To identify the causative mutation in a canine cone-rod dystrophy (crd3) that segregates as an adult onset disorder in the Glen of Imaal Terrier breed of dog. METHODS Glen of Imaal Terriers were ascertained for crd3 phenotype by clinical ophthalmoscopic examination, and in selected cases by electroretinography. Blood samples from affected cases and non-affected controls were collected and used, after DNA extraction, to undertake a genome-wide association study using Affymetrix Version 2 Canine single nucleotide polymorphism chips and 250K Sty Assay protocol. Positional candidate gene analysis was undertaken for genes identified within the peak-association signal region. Retinal morphology of selected crd3-affected dogs was evaluated by light and electron microscopy. RESULTS A peak association signal exceeding genome-wide significance was identified on canine chromosome 16. Evaluation of genes in this region suggested A Disintegrin And Metalloprotease domain, family member 9 (ADAM9), identified concurrently elsewhere as the cause of human cone-rod dystrophy 9 (CORD9), as a strong positional candidate for canine crd3. Sequence analysis identified a large genomic deletion (over 20 kb) that removed exons 15 and 16 from the ADAM9 transcript, introduced a premature stop, and would remove critical domains from the encoded protein. Light and electron microscopy established that, as in ADAM9 knockout mice, the primary lesion in crd3 appears to be a failure of the apical microvilli of the retinal pigment epithelium to appropriately invest photoreceptor outer segments. By electroretinography, retinal function appears normal in very young crd3-affected dogs, but by 15 months of age, cone dysfunction is present. Subsequently, both rod and cone function degenerate. CONCLUSIONS Identification of this ADAM9 deletion in crd3-affected dogs establishes this canine disease as orthologous to CORD9 in humans, and offers opportunities for further characterization of the disease process, and potential for genetic therapeutic intervention.
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Affiliation(s)
- Orly Goldstein
- Baker Institute for Animal Health, Cornell University College of Veterinary Medicine, Ithaca, NY
| | - Jason G. Mezey
- Department of Biological Statistics and Computational Biology, Cornell University, Ithaca, NY,Department of Genetic Medicine, Weill Cornell Medical College, NY, NY
| | - Adam R. Boyko
- Department of Genetics, Stanford University School of Medicine, Stanford, CA
| | - Chuan Gao
- Department of Biological Statistics and Computational Biology, Cornell University, Ithaca, NY
| | - Wei Wang
- Microarray Core Facility, Cornell University, Ithaca, NY
| | | | - Lynne J. Anguish
- Baker Institute for Animal Health, Cornell University College of Veterinary Medicine, Ithaca, NY
| | - Julie Ann Jordan
- Baker Institute for Animal Health, Cornell University College of Veterinary Medicine, Ithaca, NY
| | | | - Gustavo D. Aguirre
- School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA
| | - Gregory M. Acland
- Baker Institute for Animal Health, Cornell University College of Veterinary Medicine, Ithaca, NY
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218
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Hernández M, Pearce-Kelling SE, Rodriguez FD, Aguirre GD, Vecino E. Altered expression of retinal molecular markers in the canine RPE65 model of Leber congenital amaurosis. Invest Ophthalmol Vis Sci 2010; 51:6793-802. [PMID: 20671290 DOI: 10.1167/iovs.10-5213] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Leber congenital amaurosis (LCA) is a group of childhood-onset retinal diseases characterized by severe visual impairment or blindness. One form is caused by mutations in the RPE65 gene, which encodes the retinal pigment epithelium (RPE) isomerase. In this study, the retinal structure and expression of molecular markers for different retinal cell types were characterized, and differences between control and RPE65 mutant dogs during the temporal evolution of the disease were analyzed. METHODS Retinas from normal and mutant dogs of different ages were examined by immunofluorescence with a panel of 16 different antibodies. RESULTS Cones and rods were preserved in the mutant retinas, and the number of cones was normal. However, there was altered expression of cone arrestin and delocalization of rod opsin. The ON bipolar cells showed sprouting of the dendritic arbors toward the outer nuclear layer (ONL) and retraction of their axons in the inner nuclear layer (INL). A decreased expression of GABA, and an increased expression of intermediate filament glial markers was also found in the mutant retinas. These changes were more evident in the adult than the young mutant retinas. CONCLUSIONS The structure of the retina is well preserved in the mutant retina, but several molecular changes take place in photoreceptors and in bipolar and amacrine cells. Some of these changes are structural, whereas others reflect a change in localization of the examined proteins. This study provides new information that can be applied to the interpretation of outcomes of retinal gene therapy in animal models and humans.
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Affiliation(s)
- Maria Hernández
- Department of Cell Biology and Histology, University of the Basque Country (UPV/EHU), Vizcaya, Spain
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219
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220
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Sleeper MM, Bish LT, Sweeney HL. Status of therapeutic gene transfer to treat canine dilated cardiomyopathy in dogs. Vet Clin North Am Small Anim Pract 2010; 40:717-24. [PMID: 20610021 DOI: 10.1016/j.cvsm.2010.03.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Therapeutic gene transfer holds promise as a way to treat dilated cardiomyopathy from any underlying cause because the approach attempts to address metabolic disturbances that occur at the molecular level of the failing heart. Calcium-handling abnormalities and increased rates of apoptosis are abnormalities that occur in many types of heart disease, and gene therapies that target these metabolic defects have proven to be beneficial in numerous rodent models of heart disease. The authors are currently evaluating this approach to treat canine idiopathic dilated cardiomyopathy.
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Affiliation(s)
- Meg M Sleeper
- Department of Clinical Studies, University of Pennsylvania Veterinary School, Philadelphia, PA 19104, USA.
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221
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Abstract
Ocular gene therapy is becoming a well-established field. Viral gene therapies for the treatment of Leber's congentinal amaurosis (LCA) are in clinical trials, and many other gene therapy approaches are being rapidly developed for application to diverse ophthalmic pathologies. Of late, development of non-viral gene therapies has been an area of intense focus and one technology, polymer-compacted DNA nanoparticles, is especially promising. However, development of pharmaceutically and clinically viable therapeutics depends not only on having an effective and safe vector but also on a practical treatment strategy. Inherited retinal pathologies are caused by mutations in over 220 genes, some of which contain over 200 individual disease-causing mutations, which are individually very rare. This review will focus on both the progress and future of nanoparticles and also on what will be required to make them relevant ocular pharmaceutics.
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Affiliation(s)
- Shannon M Conley
- University of Oklahoma Health Sciences Center, Department of Cell Biology, BMSB 781, 940 Stanton L. Young Blvd, Oklahoma City, OK 73104, USA
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222
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A 350 bp region of the proximal promoter of Rds drives cell-type specific gene expression. Exp Eye Res 2010; 91:186-94. [PMID: 20447394 DOI: 10.1016/j.exer.2010.04.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2009] [Revised: 04/23/2010] [Accepted: 04/26/2010] [Indexed: 11/23/2022]
Abstract
RDS (retinal degeneration slow) is a photoreceptor-specific tetraspanin protein required for the biogenesis and maintenance of rod and cone outer segments. Mutations in the Rds gene are associated with multiple forms of rod- and cone-dominant retinal degeneration. To gain more insight into the mechanisms underlying the regulation of this gene, the identification of regulatory sequences within the promoter of Rds was undertaken. A 3.5 kb fragment of the 5' flanking region of the mouse Rds gene was isolated and binding sites for Crx, Otx2, Nr2e3, RXR family members, Mef2C, Esrrb, NF1, AP1, and SP1 in addition to several E-boxes, GC-boxes and GAGA-boxes were identified. Crx binding sequences were conserved in all mammalian species examined. Truncation expression analysis of the Rds promoter region in Y-79 retinoblastoma cells showed maximal activity in the 350 bp proximal promoter region. We also show that inclusion of more distal fragments reduced promoter activity to the basal level, and that the promoter activities are cell-type and direction specific. Co-transfection with Nrl increased promoter activity, suggesting that this gene positively regulates Rds expression. Based on these findings, a relatively small fragment of the Rds promoter may be useful in future gene transfer studies to drive gene expression in photoreceptors.
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223
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Beltran WA, Boye SL, Boye SE, Chiodo VA, Lewin AS, Hauswirth WW, Aguirre GD. rAAV2/5 gene-targeting to rods:dose-dependent efficiency and complications associated with different promoters. Gene Ther 2010; 17:1162-74. [PMID: 20428215 PMCID: PMC2914811 DOI: 10.1038/gt.2010.56] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
A prerequisite for using corrective gene therapy to treat humans with inherited retinal degenerative diseases that affect primarily rods is to develop viral vectors that target specifically this population of photoreceptors. The delivery of a viral vector with photoreceptor tropism coupled with a rod-specific promoter is likely to be the safest and most efficient approach to target expression of the therapeutic gene to rods. Three promoters that included a fragment of the proximal mouse opsin promoter (mOP), the human G-protein coupled receptor protein kinase 1 promoter (hGRK1), or the cytomegalovirus immediate early enhancer combined with the chicken beta actin proximal promoter CBA) were evaluated for their specificity and robustness in driving GFP reporter gene expression in rods, when packaged in a recombinant adeno-associated viral vector of serotype 2/5 (AAV2/5), and delivered via subretinal injection to the normal canine retina. Photoreceptor specific promoters (mOP, hGRK1) targeted robust GFP expression to rods, while the ubiquitously expressed CBA promoter led to transgene expression in the retinal pigment epithelium, rods, cones and rare Müller, horizontal and ganglion cells. Late onset inflammation was frequently observed both clinically and histologically with all three constructs when the highest viral titers were injected. Cone loss in the injected regions of the retinas that received the highest titers occurred with both the hGRK1 and CBA promoters. Efficient and specific rod transduction, together with preservation of retinal structure was achieved with both mOP and hGRK1 promoters when viral titers in the order of 1011 vg/ml were used.
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Affiliation(s)
- W A Beltran
- Section of Ophthalmology, Department of Clinical Studies School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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224
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Cideciyan AV. Leber congenital amaurosis due to RPE65 mutations and its treatment with gene therapy. Prog Retin Eye Res 2010; 29:398-427. [PMID: 20399883 DOI: 10.1016/j.preteyeres.2010.04.002] [Citation(s) in RCA: 178] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Leber congenital amaurosis (LCA) is a rare hereditary retinal degeneration caused by mutations in more than a dozen genes. RPE65, one of these mutated genes, is highly expressed in the retinal pigment epithelium where it encodes the retinoid isomerase enzyme essential for the production of chromophore which forms the visual pigment in rod and cone photoreceptors of the retina. Congenital loss of chromophore production due to RPE65-deficiency together with progressive photoreceptor degeneration cause severe and progressive loss of vision. RPE65-associated LCA recently gained recognition outside of specialty ophthalmic circles due to early success achieved by three clinical trials of gene therapy using recombinant adeno-associated virus (AAV) vectors. The trials were built on multitude of basic, pre-clinical and clinical research defining the pathophysiology of the disease in human subjects and animal models, and demonstrating the proof-of-concept of gene (augmentation) therapy. Substantial gains in visual function of clinical trial participants provided evidence for physiologically relevant biological activity resulting from a newly introduced gene. This article reviews the current knowledge on retinal degeneration and visual dysfunction in animal models and human patients with RPE65 disease, and examines the consequences of gene therapy in terms of improvement of vision reported.
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Affiliation(s)
- Artur V Cideciyan
- Scheie Eye Institute, University of Pennsylvania, 51 North 39th St, Philadelphia, PA 19104, USA.
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225
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Komáromy AM, Alexander JJ, Rowlan JS, Garcia MM, Chiodo VA, Kaya A, Tanaka JC, Acland GM, Hauswirth WW, Aguirre GD. Gene therapy rescues cone function in congenital achromatopsia. Hum Mol Genet 2010; 19:2581-93. [PMID: 20378608 DOI: 10.1093/hmg/ddq136] [Citation(s) in RCA: 195] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The successful restoration of visual function with recombinant adeno-associated virus (rAAV)-mediated gene replacement therapy in animals and humans with an inherited disease of the retinal pigment epithelium has ushered in a new era of retinal therapeutics. For many retinal disorders, however, targeting of therapeutic vectors to mutant rods and/or cones will be required. In this study, the primary cone photoreceptor disorder achromatopsia served as the ideal translational model to develop gene therapy directed to cone photoreceptors. We demonstrate that rAAV-mediated gene replacement therapy with different forms of the human red cone opsin promoter led to the restoration of cone function and day vision in two canine models of CNGB3 achromatopsia, a neuronal channelopathy that is the most common form of achromatopsia in man. The robustness and stability of the observed treatment effect was mutation independent, but promoter and age dependent. Subretinal administration of rAAV5-hCNGB3 with a long version of the red cone opsin promoter in younger animals led to a stable therapeutic effect for at least 33 months. Our results hold promise for future clinical trials of cone-directed gene therapy in achromatopsia and other cone-specific disorders.
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Affiliation(s)
- András M Komáromy
- Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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226
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Berger W, Kloeckener-Gruissem B, Neidhardt J. The molecular basis of human retinal and vitreoretinal diseases. Prog Retin Eye Res 2010; 29:335-75. [PMID: 20362068 DOI: 10.1016/j.preteyeres.2010.03.004] [Citation(s) in RCA: 404] [Impact Index Per Article: 28.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
During the last two to three decades, a large body of work has revealed the molecular basis of many human disorders, including retinal and vitreoretinal degenerations and dysfunctions. Although belonging to the group of orphan diseases, they affect probably more than two million people worldwide. Most excitingly, treatment of a particular form of congenital retinal degeneration is now possible. A major advantage for treatment is the unique structure and accessibility of the eye and its different components, including the vitreous and retina. Knowledge of the many different eye diseases affecting retinal structure and function (night and colour blindness, retinitis pigmentosa, cone and cone rod dystrophies, photoreceptor dysfunctions, as well as vitreoretinal traits) is critical for future therapeutic development. We have attempted to present a comprehensive picture of these disorders, including biological, clinical, genetic and molecular information. The structural organization of the review leads the reader through non-syndromic and syndromic forms of (i) rod dominated diseases, (ii) cone dominated diseases, (iii) generalized retinal degenerations and (iv) vitreoretinal disorders, caused by mutations in more than 165 genes. Clinical variability and genetic heterogeneity have an important impact on genetic testing and counselling of affected families. As phenotypes do not always correlate with the respective genotypes, it is of utmost importance that clinicians, geneticists, counsellors, diagnostic laboratories and basic researchers understand the relationships between phenotypic manifestations and specific genes, as well as mutations and pathophysiologic mechanisms. We discuss future perspectives.
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Affiliation(s)
- Wolfgang Berger
- Division of Medical Molecular Genetics and Gene Diagnostics, Institute of Medical Genetics, University of Zurich, Schorenstrasse 16, CH-8603 Schwerzenbach, Switzerland.
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227
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Pritchard CD, Arnér KM, Neal RA, Neeley WL, Bojo P, Bachelder E, Holz J, Watson N, Botchwey EA, Langer RS, Ghosh FK. The use of surface modified poly(glycerol-co-sebacic acid) in retinal transplantation. Biomaterials 2010; 31:2153-62. [PMID: 19962754 PMCID: PMC3117293 DOI: 10.1016/j.biomaterials.2009.11.074] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2009] [Accepted: 11/23/2009] [Indexed: 11/18/2022]
Abstract
Retinal transplantation experiments have advanced considerably during recent years, but remaining diseased photoreceptor cells in the host retina and inner retinal cells in the transplant physically obstruct the development of graft-host neuronal contacts which are required for vision. Recently, we developed methods for the isolation of donor photoreceptor layers in vitro, and the selective removal of host photoreceptors in vivo using biodegradable elastomeric membranes composed of poly(glycerol-co-sebacic acid) (PGS). Here, we report the surface modification of PGS membranes to promote the attachment of photoreceptor layers, allowing the resulting composite to be handled surgically as a single entity. PGS membranes were chemically modified with peptides containing an arginine-glycine-aspartic acid (RGD) extracellular matrix ligand sequence. PGS membranes were also coated with electrospun nanofiber meshes, containing laminin and poly(epsilon-caprolactone) (PCL). Following in vitro co-culture of biomaterial membranes with isolated embryonic retinal tissue, composites were tested for surgical handling and examined with hematoxylin and eosin staining and immunohistochemical markers. Electrospun nanofibers composed of laminin and PCL promoted sufficient cell adhesion for simultaneous transplantation of isolated photoreceptor layers and PGS membranes. Composites developed large populations of recoverin and rhodopsin labeled photoreceptors. Furthermore, ganglion cells, rod bipolar cells and AII amacrine cells were absent in co-cultured retinas as observed by neurofilament, PKC and parvalbumin labeling respectively. These results facilitate retinal transplantation experiments in which a composite graft composed of a biodegradable membrane adhered to an immature retina dominated by photoreceptor cells may be delivered in a single surgery, with the possibility of improving graft-host neuronal connections.
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Affiliation(s)
- Christopher D Pritchard
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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228
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Wang S, Lu B, Girman S, Duan J, McFarland T, Zhang QS, Grompe M, Adamus G, Appukuttan B, Lund R. Non-invasive stem cell therapy in a rat model for retinal degeneration and vascular pathology. PLoS One 2010; 5:e9200. [PMID: 20169166 PMCID: PMC2821411 DOI: 10.1371/journal.pone.0009200] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2009] [Accepted: 01/21/2010] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Retinitis pigmentosa (RP) is characterized by progressive night blindness, visual field loss, altered vascular permeability and loss of central vision. Currently there is no effective treatment available except gene replacement therapy has shown promise in a few patients with specific gene defects. There is an urgent need to develop therapies that offer generic neuro-and vascular-protective effects with non-invasive intervention. Here we explored the potential of systemic administration of pluripotent bone marrow-derived mesenchymal stem cells (MSCs) to rescue vision and associated vascular pathology in the Royal College Surgeons (RCS) rat, a well-established animal model for RP. METHODOLOGY/PRINCIPAL FINDINGS Animals received syngeneic MSCs (1x10(6) cells) by tail vein at an age before major photoreceptor loss. PRINCIPAL RESULTS both rod and cone photoreceptors were preserved (5-6 cells thick) at the time when control animal has a single layer of photoreceptors remained; Visual function was significantly preserved compared with controls as determined by visual acuity and luminance threshold recording from the superior colliculus; The number of pathological vascular complexes (abnormal vessels associated with migrating pigment epithelium cells) and area of vascular leakage that would ordinarily develop were dramatically reduced; Semi-quantitative RT-PCR analysis indicated there was upregulation of growth factors and immunohistochemistry revealed that there was an increase in neurotrophic factors within eyes of animals that received MSCs. CONCLUSIONS/SIGNIFICANCE These results underscore the potential application of MSCs in treating retinal degeneration. The advantages of this non-invasive cell-based therapy are: cells are easily isolated and can be expanded in large quantity for autologous graft; hypoimmunogenic nature as allogeneic donors; less controversial in nature than other stem cells; can be readministered with minor discomfort. Therefore, MSCs may prove to be the ideal cell source for auto-cell therapy for retinal degeneration and other ocular vascular diseases.
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Affiliation(s)
- Shaomei Wang
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States of America.
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229
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Rafat M, Cléroux CA, Fong WG, Baker AN, Leonard BC, O'Connor MD, Tsilfidis C. PEG-PLA microparticles for encapsulation and delivery of Tat-EGFP to retinal cells. Biomaterials 2010; 31:3414-21. [PMID: 20149443 DOI: 10.1016/j.biomaterials.2010.01.031] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2009] [Accepted: 01/09/2010] [Indexed: 12/14/2022]
Abstract
The efficient and controlled delivery of genes and proteins to retinal cells remains a challenge. In this study, we evaluated polyethylene glycol-polylactic acid (PEG-PLA) microparticles for encapsulation and delivery of a Transactivator of transcription-enhanced green fluorescent protein fusion (Tat-EGFP) to retinal cells. Our main objective was to develop a microparticle system that delivers Tat-EGFP with an initial rapid release (within 24 h) followed by a sustained release. We prepared four different formulations of Tat-EGFP encapsulated PEG-PLA particles to investigate the effects of protein and polymer concentrations on particle morphology and protein release, using scanning electron microscopy (SEM) and fluorometry techniques. The optimum formulation was selected based on higher protein release, and smaller particle size. The optimum formulation was then tested in vitro for cell biocompatibility and protein internalization, and in vivo for cellular toxicity following sub-retinal injections into rat eyes. The results suggest that PEG-PLA microparticles can deliver proteins in cell culture allowing protein internalization in as little as 1 h. In vivo, protein was shown to localize within the photoreceptor layer of the retina, and persist for at least 9 weeks with no observed toxicity.
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Affiliation(s)
- Mehrdad Rafat
- Ottawa Hospital Research Institute, Ottawa Hospital, General Division, Ottawa, ON, Canada
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230
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Gene therapy in the Retinal Degeneration Slow model of retinitis pigmentosa. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 664:611-9. [PMID: 20238065 DOI: 10.1007/978-1-4419-1399-9_70] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Human blinding disorders are often initiated by hereditary mutations that insult rod and/or cone photoreceptors and cause subsequent cellular death. Generally, the disease phenotype can be predicted from the specific mutation as many photoreceptor genes are specific to rods or cones; however certain genes, such as Retinal Degeneration Slow (RDS), are expressed in both cell types and cause different forms of retinal disease affecting rods, cones, or both photoreceptors. RDS is a transmembrane glycoprotein critical for photoreceptor outer segment disc morphogenesis, structural maintenance, and renewal. Studies using animal models with Rds mutations provide valuable insight into Rds gene function and regulation; and a better understanding of the physiology, pathology, and underlying degenerative mechanisms of inherited retinal disease. Furthermore, these models are an excellent tool in the process of developing therapeutic interventions for the treatment of inherited retinal degenerations. In this paper, we review these topics with particular focus on the use of rds models in gene therapy.
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231
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232
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Chung DC, Traboulsi EI. Leber congenital amaurosis: clinical correlations with genotypes, gene therapy trials update, and future directions. J AAPOS 2009; 13:587-92. [PMID: 20006823 DOI: 10.1016/j.jaapos.2009.10.004] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2009] [Revised: 10/07/2009] [Accepted: 10/07/2009] [Indexed: 02/06/2023]
Abstract
Leber congenital amaurosis comprises a group of early onset childhood retinal dystrophies, characterized by vision loss, nystagmus, and severe retinal dysfunction. To date, 15 causative genes have been identified that account for the heterogeneous presentation and clinical course. Knowledge of key aspects of phenotype and clinical course can contribute to the determination of a precise genetic etiology using genetic testing. Gene-based therapies are emerging, and knowledge of a patient's genotype is essential. A review of clinical presentation and disease course, their correlation to specific genotypes, and underlying physiological mechanisms, coupled with the latest results of human gene therapy trials, will assist the clinician in patient diagnosis and counseling.
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Affiliation(s)
- Daniel C Chung
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania
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233
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Cideciyan AV, Hauswirth WW, Aleman TS, Kaushal S, Schwartz SB, Boye SL, Windsor EAM, Conlon TJ, Sumaroka A, Pang JJ, Roman AJ, Byrne BJ, Jacobson SG. Human RPE65 gene therapy for Leber congenital amaurosis: persistence of early visual improvements and safety at 1 year. Hum Gene Ther 2009; 20:999-1004. [PMID: 19583479 DOI: 10.1089/hum.2009.086] [Citation(s) in RCA: 251] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Human gene therapy with rAAV2-vector was performed for the RPE65 form of childhood blindness called Leber congenital amaurosis. In three contemporaneous studies by independent groups, the procedure was deemed safe and there was evidence of visual gain in the short term. At 12 months after treatment, our young adult subjects remained healthy and without vector-related serious adverse events. Results of immunological assays to identify reaction to AAV serotype 2 capsid were unchanged from baseline measurements. Results of clinical eye examinations of study and control eyes, including visual acuities and central retinal structure by in vivo microscopy, were not different from those at the 3-month time point. The remarkable improvements in visual sensitivity we reported by 3 months were unchanged at 12 months. The retinal extent and magnitude of rod and cone components of the visual sensitivity between 3 and 12 months were also the same. The safety and efficacy of human retinal gene transfer with rAAV2-RPE65 vector extends to at least 1 year posttreatment.
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Affiliation(s)
- Artur V Cideciyan
- Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA 19104, USA.
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234
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Gene therapy for Leber's congenital amaurosis is safe and effective through 1.5 years after vector administration. Mol Ther 2009; 18:643-50. [PMID: 19953081 PMCID: PMC2839440 DOI: 10.1038/mt.2009.277] [Citation(s) in RCA: 406] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The safety and efficacy of gene therapy for inherited retinal diseases is being tested in humans affected with Leber's congenital amaurosis (LCA), an autosomal recessive blinding disease. Three independent studies have provided evidence that the subretinal administration of adeno-associated viral (AAV) vectors encoding RPE65 in patients affected with LCA2 due to mutations in the RPE65 gene, is safe and, in some cases, results in efficacy. We evaluated the long-term safety and efficacy (global effects on retinal/visual function) resulting from subretinal administration of AAV2-hRPE65v2. Both the safety and the efficacy noted at early timepoints persist through at least 1.5 years after injection in the three LCA2 patients enrolled in the low dose cohort of our trial. A transient rise in neutralizing antibodies to AAV capsid was observed but there was no humoral response to RPE65 protein. The persistence of functional amelioration suggests that AAV-mediated gene transfer to the human retina does not elicit immunological responses which cause significant loss of transduced cells. The persistence of physiologic effect supports the possibility that gene therapy may influence LCA2 disease progression. The safety of the intervention and the stability of the improvement in visual and retinal function in these subjects support the use of AAV-mediated gene augmentation therapy for treatment of inherited retinal diseases.
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235
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Affiliation(s)
- Frans P M Cremers
- Department of Human Genetics, Radboud University Nijmegen Medical Centre, 6500 HB Nijmegen, Netherlands.
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236
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Maguire AM, High KA, Auricchio A, Wright JF, Pierce EA, Testa F, Mingozzi F, Bennicelli JL, Ying GS, Rossi S, Fulton A, Marshall KA, Banfi S, Chung DC, Morgan JIW, Hauck B, Zelenaia O, Zhu X, Raffini L, Coppieters F, De Baere E, Shindler KS, Volpe NJ, Surace EM, Acerra C, Lyubarsky A, Redmond TM, Stone E, Sun J, McDonnell JW, Leroy BP, Simonelli F, Bennett J. Age-dependent effects of RPE65 gene therapy for Leber's congenital amaurosis: a phase 1 dose-escalation trial. Lancet 2009; 374:1597-605. [PMID: 19854499 PMCID: PMC4492302 DOI: 10.1016/s0140-6736(09)61836-5] [Citation(s) in RCA: 632] [Impact Index Per Article: 42.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
BACKGROUND Gene therapy has the potential to reverse disease or prevent further deterioration of vision in patients with incurable inherited retinal degeneration. We therefore did a phase 1 trial to assess the effect of gene therapy on retinal and visual function in children and adults with Leber's congenital amaurosis. METHODS We assessed the retinal and visual function in 12 patients (aged 8-44 years) with RPE65-associated Leber's congenital amaurosis given one subretinal injection of adeno-associated virus (AAV) containing a gene encoding a protein needed for the isomerohydrolase activity of the retinal pigment epithelium (AAV2-hRPE65v2) in the worst eye at low (1.5 x 10(10) vector genomes), medium (4.8 x 10(10) vector genomes), or high dose (1.5 x 10(11) vector genomes) for up to 2 years. FINDINGS AAV2-hRPE65v2 was well tolerated and all patients showed sustained improvement in subjective and objective measurements of vision (ie, dark adaptometry, pupillometry, electroretinography, nystagmus, and ambulatory behaviour). Patients had at least a 2 log unit increase in pupillary light responses, and an 8-year-old child had nearly the same level of light sensitivity as that in age-matched normal-sighted individuals. The greatest improvement was noted in children, all of whom gained ambulatory vision. The study is registered with ClinicalTrials.gov, number NCT00516477. INTERPRETATION The safety, extent, and stability of improvement in vision in all patients support the use of AAV-mediated gene therapy for treatment of inherited retinal diseases, with early intervention resulting in the best potential gain. FUNDING Center for Cellular and Molecular Therapeutics at the Children's Hospital of Philadelphia, Foundation Fighting Blindness, Telethon, Research to Prevent Blindness, F M Kirby Foundation, Mackall Foundation Trust, Regione Campania Convenzione, European Union, Associazione Italiana Amaurosi Congenita di Leber, Fund for Scientific Research, Fund for Research in Ophthalmology, and National Center for Research Resources.
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Affiliation(s)
- Albert M Maguire
- F M Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA 19104, USA
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237
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Ding XQ, Quiambao AB, Fitzgerald JB, Cooper MJ, Conley SM, Naash MI. Ocular delivery of compacted DNA-nanoparticles does not elicit toxicity in the mouse retina. PLoS One 2009; 4:e7410. [PMID: 19823583 PMCID: PMC2756629 DOI: 10.1371/journal.pone.0007410] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2009] [Accepted: 09/10/2009] [Indexed: 12/14/2022] Open
Abstract
Subretinal delivery of polyethylene glycol-substituted lysine peptide (CK30PEG)-compacted DNA nanoparticles results in efficient gene expression in retinal cells. This work evaluates the ocular safety of compacted DNA nanoparticles. CK30PEG-compacted nanoparticles containing an EGFP expression plasmid were subretinally injected in adult mice (1 µl at 0.3, 1.0 and 3.0 µg/µl). Retinas were examined for signs of inflammation at 1, 2, 4 and 7 days post-injection. Neither infiltration of polymorphonuclear neutrophils or lymphocytes was detected in retinas. In addition, elevation of macrophage marker F4/80 or myeloid marker myeloperoxidase was not detected in the injected eyes. The chemokine KC mRNA increased 3–4 fold in eyes injected with either nanoparticles or saline at 1 day post-injection, but returned to control levels at 2 days post-injection. No elevation of KC protein was observed in these mice. The monocyte chemotactic protein-1, increased 3–4 fold at 1 day post-injection for both nanoparticle and saline injected eyes, but also returned to control levels at 2 days. No elevations of tumor necrosis factor alpha mRNA or protein were detected. These investigations show no signs of local inflammatory responses associated with subretinal injection of compacted DNA nanoparticles, indicating that the retina may be a suitable target for clinical nanoparticle-based interventions.
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Affiliation(s)
- Xi-Qin Ding
- The Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America.
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238
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Abstract
PURPOSE OF REVIEW Ocular gene therapy has made significant advances due to improvements in viral vector delivery methods. Recent clinical trials for the treatment of Leber's congenital amaurosis have provided evidence for successful in-vivo gene therapy in humans. RECENT FINDINGS Gene therapy for ocular disease has been under investigation just over 15 years. Recently, the first human gene therapy trials for retinal degeneration were undertaken with encouraging preliminary safety and efficacy findings. Building on previous success in reversing blindness in animal models of Leber's congenital amaurosis, several groups proceeded with adeno-associated virus-mediated gene replacement. Many of the humans demonstrated increases in light sensitivity and in visual acuity. Subjective improvements in vision were corroborated in some cases by objective tests such as pupillary light response and nystagmography. Although much of the work in ocular gene therapy has involved retinal applications, significant progress has been seen in other aspects of ophthalmology. SUMMARY Ongoing human clinical trials support the safety and efficacy of adeno-associated virus-mediated gene therapy for retinal disease. These and other studies will establish the foundation for methodology to treat additional ocular diseases using gene therapy strategies.
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239
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Petersen-Jones S, Bartoe J, Fischer A, Scott M, Boye S, Chiodo V, Hauswirth W. AAV retinal transduction in a large animal model species: comparison of a self-complementary AAV2/5 with a single-stranded AAV2/5 vector. Mol Vis 2009; 15:1835-42. [PMID: 19756181 PMCID: PMC2743804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2009] [Accepted: 09/01/2009] [Indexed: 12/02/2022] Open
Abstract
PURPOSE To compare self-complementary (sc) and single-stranded (ss) adeno-associated viral 2/5 (AAV2/5) vectors for retinal cell transduction in the dog when delivered by subretinal injection. METHODS ScAAV2/5 and ssAAV2/5 vectors encoding enhanced green fluorescent protein (GFP) under control of the chicken beta actin promoter were prepared to the same titer. Equal amounts of viral particles were delivered into the subretinal spaces of both eyes of two dogs. In each dog, one eye received the scAAV2/5 and the other the ssAAV2/5. In vivo expression of GFP was monitored ophthalmoscopically. The dogs were sacrificed, and their retinas were examined by fluorescent microscopy and immunohistochemistry to determine GFP expression patterns and to assay for glial reactivity. RESULTS GFP expression in the scAAV2/5 injected eyes was detectable at a much earlier time point than in the ssAAV2/5 injected eyes. Expression of GFP was also at higher levels in the scAAV2/5-injected eyes. Expression levels remained stable for the seven month duration of the study. The types of cells transduced by both vectors were similar; there was strong reporter gene expression in the RPE and photoreceptors, although not all cones in the transduced area expressed GFP. Some horizontal and Müller cells were also transduced. CONCLUSIONS When delivered by subretinal injection in the dog, scAAV2/5 induces faster and stronger transgene expression than ssAAV2/5. The spectrum of retinal neurons transduced is similar between the two vectors. These results confirm in a large animal model those previously reported in the mouse. ScAAV2/5 shows promise for use in the treatment of conditions where a rapid transgene expression is desirable. Furthermore, it may be possible to use a lower number of viral particles to achieve the same effect compared with ssAAV2/5 vectors.
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Affiliation(s)
- S.M. Petersen-Jones
- Department of Small Animal Clinical Sciences, Michigan State University, East Lansing, MI
| | - J.T. Bartoe
- Department of Small Animal Clinical Sciences, Michigan State University, East Lansing, MI
| | - A.J. Fischer
- Department of Neuroscience, The Ohio State University, Columbus, OH
| | - M. Scott
- Department of Neuroscience, The Ohio State University, Columbus, OH
| | - S.L. Boye
- Department of Ophthalmology, University of Florida, Gainesville, FL
| | - V. Chiodo
- Department of Ophthalmology, University of Florida, Gainesville, FL
| | - W.W. Hauswirth
- Department of Ophthalmology, University of Florida, Gainesville, FL
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240
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Pradhan M, Hayes I, Vincent A. An audit of genetic testing in diagnosis of inherited retinal disorders: a prerequisite for gene-specific intervention. Clin Exp Ophthalmol 2009; 37:703-11. [DOI: 10.1111/j.1442-9071.2009.02129.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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241
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Beltran WA. The use of canine models of inherited retinal degeneration to test novel therapeutic approaches. Vet Ophthalmol 2009; 12:192-204. [PMID: 19392879 DOI: 10.1111/j.1463-5224.2009.00694.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Inherited retinal degenerations (RDs) are a common cause of blindness in dogs and in humans. Over the past two decades numerous genes causally associated with these diseases have been identified and several canine models have been used to improve our understanding of the molecular mechanisms of RDs, as well as to test the proof of principle and safety of novel therapies. This review briefly summarizes the drug delivery approaches and therapeutic strategies that have been and are currently tested in dogs, with a particular emphasis on corrective gene therapy, and retinal neuroprotection.
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Affiliation(s)
- William A Beltran
- Section of Ophthalmology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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242
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Li X, Ma W, Zhuo Y, Yan RT, Wang SZ. Using neurogenin to reprogram chick RPE to produce photoreceptor-like neurons. Invest Ophthalmol Vis Sci 2009; 51:516-25. [PMID: 19628733 DOI: 10.1167/iovs.09-3822] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
PURPOSE One potential therapy for vision loss from photoreceptor degeneration is cell replacement, but this approach presents a need for photoreceptor cells. This study explores whether the retinal pigment epithelium (RPE) could be a convenient source of developing photoreceptors. METHODS The RPE of chick embryos was subjected to reprogramming by proneural genes neurogenin (ngn)1 and ngn3. The genes were introduced into the RPE through retrovirus RCAS-mediated transduction, with the virus microinjected into the eye or added to retinal pigment epithelial explant culture. The retinal pigment epithelia were then analyzed for photoreceptor traits. RESULTS In chick embryos infected with retrovirus RCAS-expressing ngn3 (RCAS-ngn3), the photoreceptor gene visinin (the equivalent of mammalian recoverin) was expressed in cells of the retinal pigment epithelial layer. When isolated and cultured as explants, retinal pigment epithelial tissues from embryos infected with RCAS-ngn3 or RCAS-ngn1 gave rise to layers of visinin-positive cells. These reprogrammed cells expressed genes of phototransduction and synapses, such as red opsin, the alpha-subunit of cone transducin, SNAP-25, and PSD-95. Reprogramming occurred with retinal pigment epithelial explants derived from virally infected embryos and with retinal pigment epithelial explants derived from normal embryos, with the recombinant viruses added at the onset of the explant culture. In addition, reprogramming took place in retinal pigment epithelial explants from both young and old embryos, from embryonic day (E)6 to E18, when the visual system becomes functional in the chick. CONCLUSIONS The results support the prospect of exploring the RPE as a convenient source of developing photoreceptors for in situ cell replacement.
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Affiliation(s)
- Xiumei Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
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243
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Ebert S, Weigelt K, Walczak Y, Drobnik W, Mauerer R, Hume DA, Weber BHF, Langmann T. Docosahexaenoic acid attenuates microglial activation and delays early retinal degeneration. J Neurochem 2009; 110:1863-75. [PMID: 19627444 DOI: 10.1111/j.1471-4159.2009.06286.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Microgliosis is a common phenomenon in neurodegenerative disorders including retinal dystrophies. We performed a detailed characterization of activated microglia in the retinoschisin (Rs1h)-deficient (Rs1h(-/Y)) mouse model of inherited retinal degeneration. To visualize and isolate microglia, we crossed Rs1h(-/Y) animals with transgenic MacGreen mice, which express green fluorescent protein under the control of the macrophage-specific csf1r promoter. Activated microglia were detected in retinal sections and whole-mounts of early postnatal MacGreen/Rs1h(-/Y) mice before the onset of overt neuronal cell death. These activated microglia contained prominent lipid droplets and analysis of the retinal lipid composition showed decreased docosahexaenoic acid (DHA) levels in Rs1h(-/Y) retinas. To establish a link between microglia activation, reduced DHA levels, and neurodegeneration, a dietary intervention study was performed. Female Rs1h(-/-) mice and their Rs1h(-/Y) litter were either subjected to a diet enriched with DHA, or a control chow lacking DHA. Supplementation with DHA enhanced photoreceptor survival and converted activated microglia to a quiescent phenotype. Furthermore, DHA, but not docosapentaenoic acid or adrenic acid reduced pro-inflammatory gene expression, migration, and lipid accumulation of cultured BV-2 microglia. We conclude that retinal DHA levels control the activity of microglia and thereby may affect the progression and extent of retinal degeneration.
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Affiliation(s)
- Stefanie Ebert
- Institute of Human Genetics, University of Regensburg, Regensburg, Germany
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244
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Tan MH, Smith AJ, Pawlyk B, Xu X, Liu X, Bainbridge JB, Basche M, McIntosh J, Tran HV, Nathwani A, Li T, Ali RR. Gene therapy for retinitis pigmentosa and Leber congenital amaurosis caused by defects in AIPL1: effective rescue of mouse models of partial and complete Aipl1 deficiency using AAV2/2 and AAV2/8 vectors. Hum Mol Genet 2009; 18:2099-114. [PMID: 19299492 PMCID: PMC2722233 DOI: 10.1093/hmg/ddp133] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2009] [Accepted: 03/17/2009] [Indexed: 01/19/2023] Open
Abstract
Defects in the photoreceptor-specific gene encoding aryl hydrocarbon receptor-interacting protein-like 1 (AIPL1) are clinically heterogeneous and present as Leber Congenital Amaurosis, the severest form of early-onset retinal dystrophy and milder forms of retinal dystrophies such as juvenile retinitis pigmentosa and dominant cone-rod dystrophy. [Perrault, I., Rozet, J.M., Gerber, S., Ghazi, I., Leowski, C., Ducroq, D., Souied, E., Dufier, J.L., Munnich, A. and Kaplan, J. (1999) Leber congenital amaurosis. Mol. Genet. Metab., 68, 200-208.] Although not yet fully elucidated, AIPL1 is likely to function as a specialized chaperone for rod phosphodiesterase (PDE). We evaluate whether AAV-mediated gene replacement therapy is able to improve photoreceptor function and survival in retinal degeneration associated with AIPL1 defects. We used two mouse models of AIPL1 deficiency simulating three different rates of photoreceptor degeneration. The Aipl1 hypomorphic (h/h) mouse has reduced Aipl1 levels and a relatively slow degeneration. Under light acceleration, the rate of degeneration in the Aipl1 h/h mouse is increased by 2-3-fold. The Aipl1-/- mouse has no functional Aipl1 and has a very rapid retinal degeneration. To treat the different rates of degeneration, two pseudotypes of recombinant adeno-associated virus (AAV) exhibiting different transduction kinetics are used for gene transfer. We demonstrate restoration of cellular function and preservation of photoreceptor cells and retinal function in Aipl1 h/h mice following gene replacement therapy using an AAV2/2 vector and in the light accelerated Aipl1 h/h model and Aipl1-/- mice using an AAV2/8 vector. We have thus established the potential of gene replacement therapy in varying rates of degeneration that reflect the clinical spectrum of disease. This is the first gene replacement study to report long-term rescue of a photoreceptor-specific defect and to demonstrate effective rescue of a rapid photoreceptor degeneration.
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MESH Headings
- Adaptor Proteins, Signal Transducing
- Animals
- Carrier Proteins/genetics
- Carrier Proteins/metabolism
- Dependovirus/genetics
- Disease Models, Animal
- Genetic Therapy
- Genetic Vectors/genetics
- Humans
- Mice
- Mice, Transgenic
- Optic Atrophy, Hereditary, Leber/genetics
- Optic Atrophy, Hereditary, Leber/physiopathology
- Optic Atrophy, Hereditary, Leber/therapy
- Photoreceptor Cells, Vertebrate/metabolism
- Retinitis Pigmentosa/genetics
- Retinitis Pigmentosa/physiopathology
- Retinitis Pigmentosa/therapy
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Affiliation(s)
- Mei Hong Tan
- Institute of Ophthalmology, NIHR Biomedical research Centre, University College London, London, UK
| | - Alexander J. Smith
- Institute of Ophthalmology, NIHR Biomedical research Centre, University College London, London, UK
| | - Basil Pawlyk
- Berman-Gund Laboratory for the Study of Retinal Degenerations, Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston, MA, USA
| | - Xiaoyun Xu
- Berman-Gund Laboratory for the Study of Retinal Degenerations, Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston, MA, USA
| | - Xiaoqing Liu
- Berman-Gund Laboratory for the Study of Retinal Degenerations, Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston, MA, USA
| | - James B. Bainbridge
- Institute of Ophthalmology, NIHR Biomedical research Centre, University College London, London, UK
| | - Mark Basche
- Institute of Ophthalmology, NIHR Biomedical research Centre, University College London, London, UK
| | - Jenny McIntosh
- Cancer Research Institute, University College London, London, UK
| | - Hoai Viet Tran
- Institute of Ophthalmology, NIHR Biomedical research Centre, University College London, London, UK
| | - Amit Nathwani
- Cancer Research Institute, University College London, London, UK
| | - Tiansen Li
- Berman-Gund Laboratory for the Study of Retinal Degenerations, Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston, MA, USA
| | - Robin R. Ali
- Institute of Ophthalmology, NIHR Biomedical research Centre, University College London, London, UK
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245
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Jacobson SG, Aleman TS, Cideciyan AV, Sumaroka A, Schwartz SB, Windsor EA, Swider M, Herrera W, Stone EM. Leber congenital amaurosis caused by Lebercilin (LCA5) mutation: retained photoreceptors adjacent to retinal disorganization. Mol Vis 2009; 15:1098-106. [PMID: 19503738 PMCID: PMC2690955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2009] [Accepted: 05/22/2009] [Indexed: 11/26/2022] Open
Abstract
PURPOSE To determine the retinal disease expression in the rare form of Leber congenital amaurosis (LCA) caused by Lebercilin (LCA5) mutation. METHODS Two young unrelated LCA patients, ages six years (P1) and 25 years (P2) at last visit, both with the same homozygous mutation in the LCA5 gene, were evaluated clinically and with noninvasive studies. En face imaging was performed with near-infrared (NIR) reflectance and autofluorescence (AF); cross-sectional retinal images were obtained with optical coherence tomography (OCT). Dark-adapted thresholds were measured in the older patient; and the transient pupillary light reflex was recorded and quantified in both patients. RESULTS Both LCA5 patients had light perception vision only, hyperopia, and nystagmus. P1 showed a prominent central island of retinal pigment epithelium (RPE) surrounded by alternating elliptical-appearing areas of decreased and increased pigmentation. Retinal laminar architecture at and near the fovea was abnormal in both patients. Foveal outer nuclear layer (ONL) was present in P1 and P2 but to different degrees. With increasing eccentricity, there was retinal laminar disorganization. Regions of pericentral and midperipheral retina in P1, but not P2, could retain measurable ONL and less laminopathy. P2 had a small central island of perception with >5 log units of sensitivity loss. Pupillary responsiveness was present in both LCA5 patients; the thresholds were abnormally elevated by >or=5.5 log units. CONCLUSIONS LCA5 patients had evidence of retained photoreceptors mainly in the central retina. Retinal remodeling was present in pericentral regions in both patients. The NIR reflectance and NIR-AF imaging in the younger patient suggested preserved RPE in retinal regions with retained photoreceptors. Detailed phenotype studies in other LCA5 patients with longitudinal follow-up will help determine the feasibility of future intervention in this rare disease.
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Affiliation(s)
- Samuel G. Jacobson
- Department of Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA
| | - Tomas S. Aleman
- Department of Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA
| | - Artur V. Cideciyan
- Department of Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA
| | - Alexander Sumaroka
- Department of Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA
| | - Sharon B. Schwartz
- Department of Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA
| | - Elizabeth A.M. Windsor
- Department of Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA
| | - Malgorzata Swider
- Department of Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA
| | - Waldo Herrera
- Department of Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA
| | - Edwin M. Stone
- Howard Hughes Medical Institute and Department of Ophthalmology, University of Iowa Hospitals and Clinics, Iowa City, IA
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246
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Jacobs JB, Dell'Osso LF, Wang ZI, Acland GM, Bennett J. Using the NAFX to measure the effectiveness over time of gene therapy in canine LCA. Invest Ophthalmol Vis Sci 2009; 50:4685-92. [PMID: 19458334 DOI: 10.1167/iovs.09-3387] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To use ocular motility recordings to determine the changes over time of infantile nystagmus syndrome (INS) in RPE65-deficient canines with Leber Congenital Amaurosis (LCA) and assess the time course of the recalibration of the ocular motor system (OMS). METHODS Nine dogs were treated bilaterally with AAV-RPE65. A second cohort of four dogs was treated with AAV2.RPE65, an optimized vector. Their fixation eye movements were recorded before treatment and at 4-week intervals for 3 months, by using high-speed (500 Hz) digital videography. The dogs were suspended in a sling and encouraged to fixate on distant (57 inches) targets at gaze angles varying between +/-15 degrees horizontally and +/-10 degrees vertically. The records for each eye were examined for qualitative changes in waveform and for quantitative changes in centralisation with the expanded nystagmus acuity function (NAFX) and compared with ERG results for restoration of receptor function. RESULTS First group: Before treatment, five of the dogs had clinically apparent INS with jerk, pendular, or both waveforms and with peak-to-peak amplitudes as great as 15 degrees . One dog had intermittent nystagmus. At the 1- and 2-month examinations, no change in nystagmus waveform or NAFX was observed in any of the initial dogs, while at 10 weeks, one dog treated bilaterally with the standard dosage showed reduced nystagmus in only one eye. The other eye did not respond to treatment, as confirmed by ERG. This result was unexpected since it was previously documented that unilateral treatment leads to bilateral reduction of INS. The other dog treated with the standard dosage showed no reduction of its small-amplitude, high-frequency pendular nystagmus despite positive ERG responses. Second group: Only one dog of the four had clinically detectable INS, similar in characteristics to that seen in the affected dogs of the first group. Unlike any previous dog studied, this one showed a damping of the nystagmus within the first 4 weeks after treatment. CONCLUSIONS In all but one of the cases in which OMS recalibration occurred, as measured by the clinical appearance of nystagmus and by quantitative measurement using the NAFX, the improvement was apparent no sooner than 10 weeks after treatment. Longer term, dose-related studies are needed to determine the minimum necessary degree of restored receptor functionality, the duration after rescue for recalibration of the OMS, and the conditions under which recalibration information can successfully affect the contralateral eye.
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Affiliation(s)
- Jonathan B Jacobs
- Daroff-Dell'Osso Ocular Motility Laboratory, Veterans Affairs Medical Center, Cleveland, OH 44106, USA.
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247
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Cai X, Conley SM, Naash MI. RPE65: role in the visual cycle, human retinal disease, and gene therapy. Ophthalmic Genet 2009; 30:57-62. [PMID: 19373675 DOI: 10.1080/13816810802626399] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
RPE65 is an isomerohydrolase expressed in retinal pigment epithelium. It is critical for the regeneration of the visual pigment necessary for both rod and cone-mediated vision. Mutations in human RPE65 cause Leber's congenital amaurosis and other forms of autosomal recessive retinitis pigmentosa which are associated with early-onset blindness. Several RPE65 animal models including two different mouse models and a naturally occurring canine model have been thoroughly characterized to determine the mechanisms that underlie RPE65 associated retinal dystrophies. More recently, substantial effort has gone into designing gene therapies for these diseases. Based on several encouraging reports from animal models, at least three clinical trials are currently underway for the treatment of LCA using modified AAV vectors carrying the RPE65 cDNA and have reported positive preliminary results.
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Affiliation(s)
- Xue Cai
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
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248
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Hauswirth WW, Aleman TS, Kaushal S, Cideciyan AV, Schwartz SB, Wang L, Conlon TJ, Boye SL, Flotte TR, Byrne BJ, Jacobson SG. Treatment of leber congenital amaurosis due to RPE65 mutations by ocular subretinal injection of adeno-associated virus gene vector: short-term results of a phase I trial. Hum Gene Ther 2009; 19:979-90. [PMID: 18774912 DOI: 10.1089/hum.2008.107] [Citation(s) in RCA: 747] [Impact Index Per Article: 49.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Leber congenital amaurosis (LCA) is a group of autosomal recessive blinding retinal diseases that are incurable. One molecular form is caused by mutations in the RPE65 (retinal pigment epithelium-specific 65-kDa) gene. A recombinant adeno-associated virus serotype 2 (rAAV2) vector, altered to carry the human RPE65 gene (rAAV2-CBSB-hRPE65), restored vision in animal models with RPE65 deficiency. A clinical trial was designed to assess the safety of rAAV2-CBSB-hRPE65 in subjects with RPE65-LCA. Three young adults (ages 21-24 years) with RPE65-LCA received a uniocular subretinal injection of 5.96 x 10(10) vector genomes in 150 microl and were studied with follow-up examinations for 90 days. Ocular safety, the primary outcome, was assessed by clinical eye examination. Visual function was measured by visual acuity and dark-adapted full-field sensitivity testing (FST); central retinal structure was monitored by optical coherence tomography (OCT). Neither vector-related serious adverse events nor systemic toxicities were detected. Visual acuity was not significantly different from baseline; one patient showed retinal thinning at the fovea by OCT. All patients self-reported increased visual sensitivity in the study eye compared with their control eye, especially noticeable under reduced ambient light conditions. The dark-adapted FST results were compared between baseline and 30-90 days after treatment. For study eyes, sensitivity increases from mean baseline were highly significant (p < 0.001); whereas, for control eyes, sensitivity changes were not significant (p = 0.99). Comparisons are drawn between the present work and two other studies of ocular gene therapy for RPE65-LCA that were carried out contemporaneously and reported.
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Affiliation(s)
- William W Hauswirth
- Department of Ophthalmology, University of Florida, Gainesville, FL 32610, USA
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249
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A partial structural and functional rescue of a retinitis pigmentosa model with compacted DNA nanoparticles. PLoS One 2009; 4:e5290. [PMID: 19390689 PMCID: PMC2669177 DOI: 10.1371/journal.pone.0005290] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2009] [Accepted: 03/19/2009] [Indexed: 12/13/2022] Open
Abstract
Previously we have shown that compacted DNA nanoparticles can drive high levels of transgene expression after subretinal injection in the mouse eye. Here we delivered compacted DNA nanoparticles containing a therapeutic gene to the retinas of a mouse model of retinitis pigmentosa. Nanoparticles containing the wild-type retinal degeneration slow (Rds) gene were injected into the subretinal space of rds+/− mice on postnatal day 5. Gene expression was sustained for up to four months at levels up to four times higher than in controls injected with saline or naked DNA. The nanoparticles were taken up into virtually all photoreceptors and mediated significant structural and biochemical rescue of the disease without histological or functional evidence of toxicity. Electroretinogram recordings showed that nanoparticle-mediated gene transfer restored cone function to a near-normal level in contrast to transfer of naked plasmid DNA. Rod function was also improved. These findings demonstrate that compacted DNA nanoparticles represent a viable option for development of gene-based interventions for ocular diseases and obviate major barriers commonly encountered with non-viral based therapies.
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250
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Naturally occurring animal models with outer retina phenotypes. Vision Res 2009; 49:2636-52. [PMID: 19375447 DOI: 10.1016/j.visres.2009.04.008] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2009] [Revised: 04/07/2009] [Accepted: 04/07/2009] [Indexed: 01/28/2023]
Abstract
Naturally occurring and laboratory generated animal models serve as powerful tools with which to investigate the etiology of human retinal degenerations, especially retinitis pigmentosa (RP), Leber congenital amaurosis (LCA), cone dystrophies (CD) and macular degeneration (MD). Much progress has been made in elucidating gene defects underlying disease, in understanding mechanisms leading to disease, and in designing molecules for translational research and gene-based therapy to interfere with the progression of disease. Key to this progress has been study of naturally occurring murine and canine retinal degeneration mutants. This article will review the history, phenotypes and gene defects of select animal models with outer retina (photoreceptor and retinal pigment epithelium) degeneration phenotypes.
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