Firsts steps in the development of a topical CeO₂NPs treatment to fight dry AMD progression using the DKOrd8 mouse model

Abstract

Purpose : Cerium oxide nanoparticles (CeO₂NPs) exhibit a high scavenging ROS activity, making them suitable for the treatment of pathologies with increased oxidative stress, like dry AMD. With the aim to generate a reliable AMD model to assess the efficacy of a CeO₂NPs topical therapy, the initial purpose was set in developing the DKOrd8 mouse, testing the efficacy of CeO₂NPs in vitro and assessing their biodistribution.

Methods : By crossing three different mouse strains, we generated the Ccl2/Cx3cr1 double knockout (DKO) mouse in C57BL/6N background (with the rd8 mutation) and assessed its retina status and visual function during 9 months through in vivo and post-mortem analyses. In parallel, we synthesized CeO₂NPs and evaluated its safety and antioxidant capacity in ARPE19 cell cultures as well as its anti-angiogenic activity in HUVEC cell cultures. We also assessed CeO₂NPs biodistribution after topical or intravitreal administration in C57BL/6N mice analyzing cerium concentration in ocular and extraocular tissues through ICP-MS.

Results : The DKOrd8 mice we generated presented disorganized retinal spots as well as a progressive reduction in retinal thickness, identified by histological evaluation and in vivo optical coherence tomography. Immunofluorescence analyses also showed increased expression of GFAP and oxidative stress markers at an early age. In addition, we observed a decreased response to light stimuli compared to C57BL/6N mice, maintained upon ageing.
CeO₂NPs-treated cells presented no toxicity and showed a dose-dependent reduction of ROS levels after induction of oxidative stress along with an inhibition of endothelial cells migration. In the biodistribution assay, we detected cerium in the retina, 24h after either intravitreal or topical administration, at a concentration of 98,18ng/mg of tissue and 47,46ng/mg of tissue respectively. Cerium was detected in other parts of the eye but not in extraocular tissues.

Conclusions : CeO₂NPs showed strong antioxidant and antiangiogenic properties in vitro and more importantly, they were able to reach the retina at significant levels after a topical administration. DKOrd8 mice presented a progressive retinal degeneration and altered retinal function. Taken together, these results set the base for the upcoming administration of CeO₂NPs in the DKOrd8 mouse, which will help us to elucidate the advantages of this promising therapy.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.