Abstract
Purpose :
Melanin is a natural pigment that is present in many tissues such as retinal pigmented epithelium (RPE) cells. The RPE melanin serves a photoprotective role, contributing to protect the light-sensitive ocular tissues against phototoxicity and oxidative stress. However, the content of RPE melanin declines with increasing age. These may lead to an increased risk for vision loss such as age-related macular degeneration (AMD). We developed ceria-coated melanin-like nanoparticles (CMNPs) with photoprotective properties, which act as an alternative of natural melanin for protecting retinal cells against blue light-induced photodamage.
Methods :
The cerium oxide was coated on the melanin matrices to form as CMNPs. We characterized the size, shape, and elemental composition through TEM, DLS, and EDS analyses. Furthermore, a blue light-exposure (BLe) system with a high level of up to 2 K lux was prepared to induce retinal photochemical damage. We investigated the photoprotective effects of CMNPs in vitro and in vivo, using non-pigmented primary pig RPEs (pRPE) cells and an Nrf2 deficient mouse model and performed a variety of experiments of Fundus, OCT, and DHE assay.
Results :
The photoprotective effect of CMNPs against a blue light-induced oxidative stress was evidenced by cell viability test. The pRPE cells were exposed to blue light (435 nm; 280 lux) for 1, 3, 6 and 24 h. Compared with CMNPs treated non-pigmented pRPE, a significant decrease in the number of viable cells were found in non-treated cells (p < 0.001), indicating that CMNPs pretreatment significantly protected the blue light-exposed pRPE cells from the photo cytotoxicity. Furthermore, we examined whether CMNPs can protect blue light induced photodamage on the Nrf2-deficient mice. At 5 days after intravitreal injection of CMNPs, mice were treated with blue light irradiation (435 nm; 2 K lux) for 3 days. Our results showed that the CMNPs-treated group were significantly alleviated light exposure-induced photodamage and ROS generation in the Nrf2 deficient mouse (***P < 0.001).
Conclusions :
CMNPs were designed to fully utilize advantageous properties of melanin and cerium oxide nanoparticles for protecting the retinal cells against blue light-induced photodamage. Our findings demonstrated that CMNPs could protect the retinal cells against a blue light-induced photodamage with photoprotection and antioxidant properties.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.