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Tshitoko Kizito Tshilenge, Baptiste Ameline, Michel Weber, Guylène Le Meur, Jack-Yves Deschamps, Alexandra Mendes-Madeira, Steven Nedellec, Véronique Blouin, Virginie Pichard, Philippe Moullier, Fabienne Rolling; Vitreous body: A barrier for AAV-mediated gene transfer to inner retinal neurons of macaque. Invest. Ophthalmol. Vis. Sci. 2016;57(12):100.
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© ARVO (1962-2015); The Authors (2016-present)
For retinal gene delivery, several studies have illustrated that AAV2/2 injected intravitreally transduces retinal ganglion cells (RGCs) efficiently in rodent models. However, considerable anatomical differences between eyes of rodent models and human subjects make difficult the translation of these results. Indeed, contrary to rodent eyes, the vitreous body fills a significantly larger space in human eyes, which consequently might be a physical barrier for vector diffusion and transduction. Because macaque eyes recapitulate the anatomical characteristics of the human eye, we evaluated the effect of the vitreous body on AAV2/2 transduction in macaque retinas following intravitreal injection.
We generated AAV2/2 vectors carrying the enhanced green fluorescence protein (eGFP) cDNA under the control of the cytomegalovirus promoter. AAV2/2 vector was administered intravitreally in macaque eyes either directly in the vitreous chamber without removing the vitreous body (n=2) or after a complete vitrectomy, a surgical procedure aiming to remove the vitreous body (n=2). Native eGFP expression was monitored by funduscopic imaging and by confocal microscopy in retinal flat mounts.
In macaque eyes where vitrectomy was performed, extensive eGFP expression was detectable in RGCs axons projecting toward the optic nerve head. The transduction efficiency was mainly localized in peripheral retina while in central retina low eGFP expression was observed except for RGCs transduction around the macular region. On the contrary, eGFP expression was not detected in central and peripheral retinas in macaque eyes in which the vitreous body was present.
This observation suggests that the vitreous body interferes in AAV2/2-mediated transduction to inner retinal neurons of macaque retinas. Our hypothesis is that the vector injected intravitreally without prior vitrectomy is obstructed by the vitreous -a gel-like structure-, which may trap the vector and in turn reduces its diffusion towards inner retinal neurons. We illustrated that vitrectomy prior vector injection is an effective procedure to overcome this physical barrier and consequently improves the transduction of RGCs in macaque retinas. Overall, these results set the stage for the translation of vitrectomy in human subjects as relevant approach to promote gene delivery to inner retinal neurons after AAV vector intravitreal administration.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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