Abstract
Purpose :
Retinitis Pigmentosa (RP) is an inherited retinal degeneration in which 4-6% of cases are caused by a mutation in the PDE6β gene. Given that gene therapy has proved effective in retinal genetic diseases, we have previously developed non-viral polymeric vectors based on PDMAEMA, capable of efficient gene delivery. Our goal was to test if our non-viral vectors, combined with optimized gene expression plasmids, can deliver and express the PDE6β gene in the retina of a mouse model of RP.
Methods :
The gene transfer efficiency of PDMAEMA polyplexes was tested by subretinal injection in WT C57Bl6 adult (3month-old, N=3) animals using a pEPito-GFP plasmid. A timecourse of retinal degeneration in the rd10 mouse was performed at P11, P18, P25 and P35 to determine the adequate injection timepoint.
At P4, rd10 mice (N=3 per condition) were injected subretinally with a 1 mL solution of PDMAEMA-pEPito-PDE6β. Naked pEPito-PDE6β plasmid was used as control. The contralateral eye in each animal as control (non-injected or sham). Animals were sacrificed at 14- and 31-days post-injection and the retinas collected for analysis. All procedures followed the Portuguese and European Union FELASA regulations for the use of animals in research and ARVO guidelines for the use of animals in ophthalmic and vision research.
Results :
The timecourse of retinal degeneration in the rd10 mouse showed significant alterations in the expression patterns of (indicar o quê) starting at P18, concomitant with a decrease in the thickness of the outer nuclear layer (ONL). Therefore, we have chosen an earlier timepoint (P4) to administer the therapeutic vector to prevent these changes.
PDMAEMA polyplexes were shown to promote expression of GFP in the RPE of the adult retina, as observed in WT mice at both 14 and 31 days post-injection.
PDMAEMA polyplexes were able to express the PDE6β gene in the mouse retina, with its expression mostly localized in the RPE and in the other segments of photoreceptors.
Conclusions :
Non-viral PDMAEMA vectors were able to express genes both in the adult and developing retina. In the retina of the rd10 mouse model of RP these vectors were able to efficiently express PDE6β, thus confirming their potential as nonviral vectors for retinal gene therapy. Further studies will focus on assessing the duration of PDE6β expression and functional rescue of the retina.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.