Temporal Distribution Patterns of Alexa Fluor 647-Conjugated CeNPs in the Mouse Retina After a Single Intravitreal Injection.

Intravitreal (IVT) injection of ophthalmic therapeutics is the most widely used drug delivery route to the posterior segment of the eye. We employed this method to deliver our inorganic, catalytic antioxidant, cerium oxide nanoparticles (CeNPs), to rodent models of retinal degeneration. A single IVT of CeNPs delays disease progression. Even though we have shown that our synthesized CeNPs are retained in the retina for over a year, we still do not know which cell types in the retina preferentially take up these nanoparticles. In this study, we examined the temporal and spatial distribution of fluorescently labeled CeNPs in retinal sections after IVT. We detected elevated fluorescent signals in all the layers where retinal neurons and glia reside and retinal pigment epithelium (RPE) up to 90 days post injection. Additionally, we found that free fluorochrome accumulated in retinal vasculature instead of retinal cells. These data suggested that CeNP-conjugation mediated the targeting of the fluorochrome to retinal cells. We propose that CeNPs can be deployed as ophthalmic carriers to the retina.