Adeno-associated virus-vectored gene therapy for retinal disease.
ABSTRACT Recombinant adeno-associated viral (AAV) vectors have become powerful gene delivery tools for the treatment of retinal degeneration in a variety of animal models that mimic corresponding human diseases. AAV vectors possess a number of features that render them ideally suited for retinal gene therapy, including a lack of pathogenicity, minimal immunogenicity, and the ability to transduce postmitotic cells in a stable and efficient manner. In the sheltered environment of the retina, AAV vectors are able to maintain high levels of transgene expression in the retinal pigmented epithelium (RPE), photoreceptors, or ganglion cells for long periods of time after a single treatment. Each cell type can be specifically targeted by choosing the appropriate combination of AAV serotype, promoter, and intraocular injection site. The focus of this review is on examples of AAV-mediated gene therapy in those animal models of inherited retinal degeneration caused by mutations directly affecting the interacting unit formed by photoreceptors and the RPE. In each case discussed, expression of the therapeutic gene resulted in significant recovery of retinal structure and/or visual function. Because of the key role of the vasculature in maintaining a healthy retina, a summary of AAV gene therapy applications in animal models of retinal neovascular diseases is also included.
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ABSTRACT: The expression of vascular endothelial growth factor (VEGF) and its high-affinity receptors VEGFR-1 and VEGFR-2 was investigated in normal eyes. Monkey and rat eyes were surgically removed in animals under deep anesthesia and immediately prepared for study. Ocular VEGF, VEGFR-1, and VEGFR-2 expression was studied using a combination of in situ hybridization, northern blot analysis, immunohistochemistry, immunoassay, and reverse transcription-polymerase chain reaction. Steady state VEGF mRNA levels were detected in the normal vascularized ocular tissues of the monkey: the conjunctiva, iris, retina, and the choroid-retinal pigment epithelial complex. VEGF121 and VEGF165 were the major isoforms identified. VEGF protein was detected in the conjunctiva, retina, and the choroid-retinal pigment epithelial complex. Retinal VEGF mRNA localized to the ganglion, inner nuclear, and retinal pigment epithelial cell layers. VEGF protein localized to these same layers and to the cones of monkey retina. VEGFR-1 and VEGFR-2 mRNAs were detected in normal monkey iris, retina, and the choroid-retinal pigment epithelial complex. In both monkey and rat eyes, VEGFR-1 and VEGFR-2 mRNAs were localized to the inner nuclear layer of the retina. VEGF, VEGFR-1, and VEGFR-2 are constitutively expressed in the vascularized tissues of normal eyes.Investigative Ophthalmology & Visual Science 09/1999; 40(9):2115-21. · 3.44 Impact Factor
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ABSTRACT: Following exposure of our eye to very intense illumination, we experience a greatly elevated visual threshold, that takes tens of minutes to return completely to normal. The slowness of this phenomenon of "dark adaptation" has been studied for many decades, yet is still not fully understood. Here we review the biochemical and physical processes involved in eliminating the products of light absorption from the photoreceptor outer segment, in recycling the released retinoid to its original isomeric form as 11-cis retinal, and in regenerating the visual pigment rhodopsin. Then we analyse the time-course of three aspects of human dark adaptation: the recovery of psychophysical threshold, the recovery of rod photoreceptor circulating current, and the regeneration of rhodopsin. We begin with normal human subjects, and then analyse the recovery in several retinal disorders, including Oguchi disease, vitamin A deficiency, fundus albipunctatus, Bothnia dystrophy and Stargardt disease. We review a large body of evidence showing that the time-course of human dark adaptation and pigment regeneration is determined by the local concentration of 11-cis retinal, and that after a large bleach the recovery is limited by the rate at which 11-cis retinal is delivered to opsin in the bleached rod outer segments. We present a mathematical model that successfully describes a wide range of results in human and other mammals. The theoretical analysis provides a simple means of estimating the relative concentration of free 11-cis retinal in the retina/RPE, in disorders exhibiting slowed dark adaptation, from analysis of psychophysical measurements of threshold recovery or from analysis of pigment regeneration kinetics.Progress in Retinal and Eye Research 06/2004; 23(3):307-80. · 9.44 Impact Factor
- Methods in Enzymology 02/2002; 346:358-77. · 2.00 Impact Factor