Antioxidant Properties of Cerium Oxide Nanoparticles Prevent Retinal Neovascular Alterations In Vitro and In Vivo

Abstract

In this study, we investigated whether cerium oxide nanoparticles (CeO2-NPs), a promising antioxidant nanomaterial, may contrast retinal vascular alterations induced by oxidative damage in vitro and in vivo. For the in vivo experiments, the light damage (LD) animal model of Age-Related Macular Degeneration (AMD) was used and the CeO2-NPs were intravitreally injected. CeO2-NPs significantly decreased vascular endothelial growth factor (VEGF) protein levels, reduced neovascularization in the deep retinal plexus, and inhibited choroidal sprouting into the photoreceptor layer. The in vitro experiments were performed on human retinal pigment epithelial (ARPE-19) cells challenged with H2O2; we demonstrated that CeO2-NPs reverted H2O2-induced oxidative stress-dependent effects on this cell model. We further investigated the RPE–endothelial cells interaction under oxidative stress conditions in the presence or absence of CeO2-NPs through two experimental paradigms: (i) treatment of human umbilical vein endothelial cells (HUVECs) with conditioned media from ARPE-19 cells, and (ii) coculture of ARPE-19 and HUVECs. In both experimental conditions, CeO2-NPs were able to revert the detrimental effect of H2O2 on angiogenesis in vitro by realigning the level of tubule formation to that of the control. Altogether, our results indicate, for the first time, that CeO2-NPs can counteract retinal neovascularization and may be a new therapeutic strategy for the treatment of wet AMD.

Dysregulation of Resolvin E1 Metabolism and Signaling in a Light-Damage Model of Age-Related Macular Degeneration

“…In the present study, we investigated for the first time RvE1 metabolism and signaling in a widely used and well characterized model of AMD, known as retinal light damage (LD), which is based on the induction of retinal degeneration through the exposure to high intensity light [ 19 , 25 , 26 , 27 ]. We hypothesized that RvE1 dysregulation may occur in AMD as one of the mechanisms at the basis of chronic inflammation typically associated with the disease.…”

“…RvE1 metabolism and signaling were investigated in the retinas of LD rats at two critical time points: (i) immediately after LD, that is when the peak of apoptosis occurs in the photoreceptors and retinal pigment epithelial (RPE) cells of the outer retina, the blood–retinal barrier (BRB) starts to disaggregate, and the degenerative mechanisms are induced [ 28 , 29 ]; and (ii) 7 days after LD, that is when photoreceptor and RPE atrophy occur in a limited area of the dorsal retina (known as hotspot) alongside BRB breakdown, functional impairment, gliosis, accumulation of autofluorescent cell debris, neovascularization, and additional molecular/degenerative events typical of an advanced AMD form [ 24 , 26 , 27 , 29 ]. In our study, the main RvE1 metabolic alterations were found 7 days after LD—as summarized in Figure 7 —when the selective RvE1 receptor ChemR23 was also significantly up-regulated compared to healthy retinas.…”

Repeated Topical Administration of 3 nm Cerium Oxide Nanoparticles Reverts Disease Atrophic Phenotype and Arrests Neovascular Degeneration in AMD Mouse Models

“…As expected, in the retina, several studies have shown the substantial therapeutic potential of CeO 2 NPs after a single intravitreal (ITV) injection in murine models with severe retinal degeneration. − ITV administration of CeO 2 NPs has demonstrated protection against acute photoreceptor degeneration by reducing ROS levels in the light-damage retinal degeneration rat model and in the tubby mouse model, all with early and severe photoreceptor degeneration. ,, The effect of CeO 2 NPs in retinal neovascularisation models has also been evaluated, with the observation of downregulation of pro-angiogenic growth factors in the Vldlr –/– mouse model and inhibition of laser-induced CNV in mice by decreasing ROS-induced VEGF expression after ITV injection . Retinal neovascularisation inhibition in the light-damage rat model and antioxidant protective effects in vitro have also been documented recently . CeO 2 NPs also exhibited the capacity to influence the immune response in the Vldlr –/– mouse model by reducing microglia activation in light-damaged retina rat models after ITV injection, and the inhibition of pro-inflammatory cytokines expression …”

“…31 Retinal neovascularisation inhibition in the light-damage rat model and antioxidant protective effects in vitro have also been documented recently. 32 CeO 2 NPs also exhibited the capacity to influence the immune response in the Vldlr −/− mouse model by reducing microglia activation in light-damaged retina rat models after ITV injection, 26 and the inhibition of proinflammatory cytokines expression. 30 However, despite the safety and catalytic -sustained through time-activity of CeO 2 NPs, ideal for chronic treatment, their current formulation as an ITV application prevents its proper exploitation in AMD, a degenerative disease with a slow progression that implies chronic treatment to ensure constant availability of the therapeutic substance for extended periods of time.…”

The Glyoxalase System Is a Novel Cargo of Amniotic Fluid Stem-Cell-Derived Extracellular Vesicles

“…GSH was measured by using the GSH assay kit (colorimetric) from Bio Vision Inc. (Milpitas, CA, USA) according to the manufacturer’s instructions as previously described [ 33 ].…”