title: Preclinical Dose-Escalation Study of Intravitreal AAV-RS1 Gene Therapy in a Mouse Model of X-linked Retinoschisis: Dose-Dependent Expression and Improved Retinal Structure and Function.
abstract: Gene therapy for inherited retinal diseases has been shown to ameliorate functional and structural defects in both animal models and in human clinical trials. X-linked retinoschisis (XLRS) is an early-age onset macular dystrophy resulting from loss of an extracellular matrix protein (RS1). In preparation for a human clinical gene therapy trial, we conducted a dose-range efficacy study of the clinical vector, a self-complementary AAV delivering a human retinoschisin (RS1) gene under control of the RS1 promoter and an interphotoreceptor binding protein enhancer (AAV8-scRS/IRBPhRS), in the retinoschisin knockout (Rs1-KO) mouse. The therapeutic vector at 1 × 10(6) to 2.5 × 10(9) (1E6-2.5E9) vector genomes (vg)/eye or vehicle was administered to one eye of 229 male Rs1-KO mice by intravitreal injection at 22 ± 3 days postnatal age (PN). Analysis of retinal function (dark-adapted electroretinogram, ERG), structure (cavities and outer nuclear layer thickness) by in vivo retinal imaging using optical coherence tomography, and retinal immunohistochemistry (IHC) for RS1 was done 3-4 months and/or 6-9 months postinjection (PI). RS1 IHC staining was dose dependent across doses ≥1E7 vg/eye, and the threshold for significant improvement in all measures of retinal structure and function was 1E8 vg/eye. Higher doses, however, did not produce additional improvement. At all doses showing efficacy, RS1 staining in Rs1-KO mouse was less than that in wild-type mice. Improvement in the ERG and RS1 staining was unchanged or greater at 6-9 months than at 3-4 months PI. This study demonstrates that vitreal administration of AAV8 scRS/IRBPhRS produces significant improvement in retinal structure and function in the mouse model of XLRS over a vector dose range that can be extended to a human trial. It indicates that a fully normal level of RS1 expression is not necessary for a therapeutic effect.
authors.affiliation: 1 National Institute on Deafness and Other Communication Disorders, National Institutes of Health , Bethesda, Maryland.
authors.forename: Ronald A
authors.initials: RA
authors.lastname: Bush
authors.affiliation: 1 National Institute on Deafness and Other Communication Disorders, National Institutes of Health , Bethesda, Maryland.
authors.forename: Yong
authors.initials: Y
authors.lastname: Zeng
authors.affiliation: 2 National Eye Institute, National Institutes of Health , Bethesda, Maryland.
authors.forename: Peter
authors.initials: P
authors.lastname: Colosi
authors.affiliation: 1 National Institute on Deafness and Other Communication Disorders, National Institutes of Health , Bethesda, Maryland.|3 Department of Ophthalmology, Lund University , Lund, Sweden .
authors.forename: Sten
authors.initials: S
authors.lastname: Kjellstrom
authors.affiliation: 2 National Eye Institute, National Institutes of Health , Bethesda, Maryland.
authors.forename: Suja
authors.initials: S
authors.lastname: Hiriyanna
authors.affiliation: 1 National Institute on Deafness and Other Communication Disorders, National Institutes of Health , Bethesda, Maryland.
authors.forename: Camasamudram
authors.initials: C
authors.lastname: Vijayasarathy
authors.affiliation: 2 National Eye Institute, National Institutes of Health , Bethesda, Maryland.
authors.forename: Maria
authors.initials: M
authors.lastname: Santos
authors.affiliation: 1 National Institute on Deafness and Other Communication Disorders, National Institutes of Health , Bethesda, Maryland.
authors.forename: Jinbo
authors.initials: J
authors.lastname: Li
authors.affiliation: 2 National Eye Institute, National Institutes of Health , Bethesda, Maryland.
authors.forename: Zhijian
authors.initials: Z
authors.lastname: Wu
authors.affiliation: 1 National Institute on Deafness and Other Communication Disorders, National Institutes of Health , Bethesda, Maryland.|2 National Eye Institute, National Institutes of Health , Bethesda, Maryland.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Sieving
mesh_terms: D000818:Animals; D015815:Cell Adhesion Molecules / Q000235:genetics* / Q000378:metabolism; D000229:Dependovirus / Q000235:genetics*; D004195:Disease Models, Animal; D004596:Electroretinography; D005136:Eye Proteins / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression; D050172:Genes, X-Linked; D015316:Genetic Therapy; D005822:Genetic Vectors / Q000008:administration & dosage / Q000235:genetics*; D007150:Immunohistochemistry; D058449:Intravitreal Injections; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D012160:Retina / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D041441:Retinoschisis / Q000175:diagnosis / Q000235:genetics* / Q000378:metabolism / Q000628:therapy; D013997:Time Factors; D041623:Tomography, Optical Coherence; D014161:Transduction, Genetic
chemical_list: D015815:Cell Adhesion Molecules; D005136:Eye Proteins; C491843:RS1 protein, mouse