AAV‐mediated gene delivery in Dp71‐null mouse model with compromised barriers

Abstract

Formation and maintenance of the blood–retinal barrier (BRB) is required for proper vision and breaching of this barrier contributes to the pathology in a wide variety of retinal conditions such as retinal detachment and diabetic retinopathy. Dystrophin Dp71 being a key membrane cytoskeletal protein, expressed mainly in Müller cells, its absence has been related to BRB permeability through delocalization and down‐regulation of the AQP4 and Kir4.1 channels. Dp71‐null mouse is thus an excellent model to approach the study of retinal pathologies showing blood–retinal barrier permeability. We aimed to investigate the participation of Müller cells in the BRB and in the inner limiting membrane of Dp71‐null mice compared with wild‐type mice in order to understand how these barriers work in this model of permeable BRB. To this aim, we used an Adeno‐associated virus (AAV) variant, ShH10‐GFP, engineered to target Müller cells specifically. ShH10 coding GFP was introduced by intravitreal injection and Müller cell transduction was studied in Dp71‐null mice in comparison to wild‐type animals. We show that Müller cell transduction follows a significantly different pattern in Dp71‐null mice indicating changes in viral cell‐surface receptors as well as differences in the permeability of the inner limiting membrane in this mouse line. However, the compromised BRB of the Dp71‐null mice does not lead to virus leakage into the bloodstream when the virus is injected intravitreally – an important consideration for AAV‐mediated retinal gene therapy. GLIA 2014;62:468–476

Noninvasive gene delivery to foveal cones for vision restoration

“…Only the PR1.7 promoter showed GFP expression in cones with minimal expression in rods and was not leaky toward the inner retina ( Figure 1F). Finally, as retinal disease state can influence AAV-mediated gene delivery and transgene expression patterns (20,21), we validated AAV2-7m8-PR1.7 vector-promoter combination in a mouse model of retinal degeneration. We injected AAV2-7m8-PR1.7-GFP intravitreally in the retinal degeneration 10 (rd10) mouse model of retinitis pigmentosa.…”

Diabetes enhances the efficacy of AAV2 vectors in the retina: therapeutic effect of AAV2 encoding vasoinhibin and soluble VEGF receptor 1

“…Diabetes alters the function and structure of all retinal cell types, 71 and loss of integrity and changes in retinal architecture are known to increase AAV vector transduction. Disruption of the inner limiting membrane caused by mild proteolytic digestion, 72 by structural changes of the Müller cell endfeet, 73 by laser pretreatment, 74 or by retinal degeneration 72 allow for enhanced AAV transduction of outer retinal cells after their intravitreal delivery. Moreover, nuclear uptake, capsid uncoating, and second-strand DNA synthesis following receptor binding are major rate-limiting steps in AAV transduction [75][76][77][78] that need to be investigated.…”

Highly Efficient Delivery of Adeno-Associated Viral Vectors to the Primate Retina

“…13,15 Experiments done in rodents, where the ILM was physically digested or was ablated via genetic manipulation followed by intravitreal delivery of AAV5, resulted in efficient transduction of outer retina. 34,37 This would suggest that AAV5 may be capable of trafficking to the outer retina when placed under the ILM. However, substantial shifts in vector tropism have been observed when the biology of the retina has been substantially perturbed, as would be the case in both of the aforementioned treatments.…”

“…35 When the ILM is physically degraded by enzymatic digestion or lacks structural integrity because of genetic manipulation, AAV transduction in both rodents and NHP may be improved. 19,36,37 However, the long-term implications of such disruption for the structure/function of the neural retina have not been investigated. To achieve more efficient and widespread transduction of primate retina by AAV, alternative delivery strategies and surgical approaches should be considered.…”