title: Direct comparison of administration routes for AAV8-mediated ocular gene therapy.
abstract: OBJECTIVE
  We recently demonstrated that direct subretinal (SR) injection of adeno-associated virus (AAV) type 8 (AAV8) into photoreceptor cells and retinal pigment epithelium (RPE) is a highly efficient model of gene delivery. The current study compared transduction efficiency and expression patterns associated with various routes of vector administration.
  
  
  METHODS
  The efficacy of intravitreal (VT), SR and subconjunctival (SC) injections for delivery of AAV8-derived vectors, i.e. those expressing luciferase (Luc) and enhanced green fluorescent protein (GFP) - AAV8/Luc and AAV8/GFP, respectively - were compared in an animal (mouse) model (n = 8 mice/group). Transduction efficiency and expression patterns were examined at post-injection weeks 1 and 2, and months 1, 3, 6 and 12 via in vivo imaging.
  
  
  RESULTS
  One year after AAV injection, AAV8/Luc-treated mice exhibited stable and sustained high expression of vector in the VT and SR groups, but not in the SC group (VT:SR:SC = 3,218:2,923:115; 1 × 10(5 )photons/s). Histological analysis showed that GFP expression was observed in the inner retina of VT group mice, and in photoreceptor cells and RPE of SR group mice, whereas no GFP expression was noted in the SC group. Electroretinography (ERG) revealed adverse effects following SR delivery.
  
  
  CONCLUSIONS
  Results suggest that both SR and VT injections of AAV8 vectors are useful routes for administering ocular gene therapy, and stress the importance of selecting an appropriate administration route, i.e. one that targets specific cells, for treating ocular disorders.
authors.affiliation: Department of Ophthalmology, Nippon Medical School, Tokyo, Japan. tutomu@nms.ac.jp
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Igarashi
authors.forename: Koichi
authors.initials: K
authors.lastname: Miyake
authors.forename: Nagisa
authors.initials: N
authors.lastname: Asakawa
authors.forename: Noriko
authors.initials: N
authors.lastname: Miyake
authors.forename: Takashi
authors.initials: T
authors.lastname: Shimada
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Takahashi
mesh_terms: D000818:Animals; D000229:Dependovirus / Q000235:genetics*; D004596:Electroretinography; D005128:Eye Diseases / Q000628:therapy; D015316:Genetic Therapy / Q000009:adverse effects / Q000379:methods*; D005822:Genetic Vectors / Q000235:genetics; D049452:Green Fluorescent Proteins / Q000235:genetics; D006801:Humans; D058449:Intravitreal Injections / Q000009:adverse effects / Q000379:methods*; D008156:Luciferases / Q000235:genetics; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D020419:Photoreceptor Cells, Vertebrate; D011897:Random Allocation; D058471:Subretinal Fluid; D014161:Transduction, Genetic / Q000379:methods; D014822:Vitreous Body
chemical_list: C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D008156:Luciferases