Inner Limiting Membrane Barriers to AAV-mediated Retinal Transduction From the Vitreous

• Published in: Molecular therapy Vol. 17; no. 12; pp. 2096 - 2102
• Main Authors: Dalkara, Deniz, Kolstad, Kathleen D, Caporale, Natalia, Visel, Meike, Klimczak, Ryan R, Schaffer, David V, Flannery, John G
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.12.2009; Elsevier Limited; Nature Publishing Group
• Subjects: Animals; Cell Membrane - metabolism; Cell Membrane Permeability; Dependovirus - genetics; Electroretinography; Enzymes; Fluorescein Angiography; Gene therapy; Gene Transfer Techniques; Genetic Vectors - administration & dosage; Genomes; Green Fluorescent Proteins - metabolism; Heparan sulfate; Localization; Neurosciences; Original; Photoreceptors; Pronase - metabolism; Rats; Rats, Sprague-Dawley; Retina; Retina - cytology; Retina - metabolism; Retina - virology; Retinal detachment; Transduction, Genetic; Vectors (Biology); Vitreous Body - metabolism; Vitreous Body - virology; United States > US; California
• ISSN: 1525-0016; 1525-0024
• DOI: 10.1038/mt.2009.181

Adeno-associated viral gene therapy has shown great promise in treating retinal disorders, with three promising clinical trials in progress. Numerous adeno-associated virus (AAV) serotypes can infect various cells of the retina when administered subretinally, but the retinal detachment accompanying this injection induces changes that negatively impact the microenvironment and survival of retinal neurons. Intravitreal administration could circumvent this problem, but only AAV2 can infect retinal cells from the vitreous, and transduction is limited to the inner retina. We therefore sought to investigate and reduce barriers to transduction from the vitreous. We fluorescently labeled several AAV serotype capsids and followed their retinal distribution after intravitreal injection. AAV2, 8, and 9 accumulate at the vitreoretinal junction. AAV1 and 5 show no accumulation, indicating a lack of appropriate receptors at the inner limiting membrane (ILM). Importantly, mild digestion of the ILM with a nonspecific protease enabled substantially enhanced transduction of multiple retinal cell types from the vitreous, with AAV5 mediating particularly remarkable expression in all retinal layers. This protease treatment has no effect on retinal function as shown by electroretinogram (ERG) and visual cortex cell population responses. These findings may help avoid limitations, risks, and damage associated with subretinal injections currently necessary for clinical gene therapy.