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

Hum Gene Ther. 2016 May;27(5):376-89. doi: 10.1089/hum.2015.142.


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.

Publication types

  • Research Support, N.I.H., Intramural

MeSH terms

  • Animals
  • Cell Adhesion Molecules / genetics*
  • Cell Adhesion Molecules / metabolism
  • Dependovirus / genetics*
  • Disease Models, Animal
  • Electroretinography
  • Eye Proteins / genetics*
  • Eye Proteins / metabolism
  • Gene Expression
  • Genes, X-Linked*
  • Genetic Therapy*
  • Genetic Vectors / administration & dosage
  • Genetic Vectors / genetics*
  • Immunohistochemistry
  • Intravitreal Injections
  • Male
  • Mice
  • Mice, Knockout
  • Retina / metabolism
  • Retina / pathology
  • Retina / physiopathology
  • Retinoschisis / diagnosis
  • Retinoschisis / genetics*
  • Retinoschisis / metabolism
  • Retinoschisis / therapy
  • Time Factors
  • Tomography, Optical Coherence
  • Transduction, Genetic


  • Cell Adhesion Molecules
  • Eye Proteins
  • RS1 protein, mouse