Abstract
Purpose: :
To investigate the retinal tropism of a scAAV2/9 vector following peripheral delivery through tail vein injection in adult mice.
Methods: :
Single strand (ss) or self-complementary (sc) AAV vectors of serotype 1 and 9 encoding the green fluorescent protein (GFP) or the murine secreted alkaline phosphatase (mSEAP) were intravenously injected in the tail vein of adult mice. Six weeks following vector administration, transgene expression in the retina was studied by biochemical, molecular and histological methods.
Results: :
We found that intravenous injection of the scAAV vectors, in particular of serotype 9, led to a significant transgene expression in different cell layers of both eyes, including the choroid and the retina. This was first observed at the DNA and protein level following intravenous injection of scAAV9-mSEAP vectors. The superiority of scAAV9 vectors was then confirmed by histological analysis after intravenous injection of scAAV9-GFP and immunodetection of the transgene product. Importantly, we detected transgene expression in cells of the retinal pigment epithelium, photoreceptor cells, cells of the inner nuclear layer, Müller cells and cells of the ganglion cell layer (RGC), although these different retinal cell types were found to be transduced with variable efficiencies. Notably, the RGC layer appeared to be transduced with the higher efficiency. Double-labelling with Brn-3a showed that a significant proportion of the GFP expressing population was retinal ganglion cells. In addition, we found high level of GFP expression outside of the retina in the choroid, the ciliary body and the optic nerve.
Conclusions: :
This study shows, for the first time, that it is possible to achieve gene delivery to the retina of adult mammals after a single intravenous administration of scAAV2/9 vectors. This less invasive approach is promising for the development of gene therapy strategies for eye disorders, and especially for neurodegenerative disease of the retina.
Keywords: gene transfer/gene therapy • retina • ganglion cells