Expression Sites of Neural Stem Cell-Related Genes in the Monkey Retina

Abstract

Objectives: Based on the hypothesis that undifferentiated retinal stem cell (RSC)-like cells exist in the fovea (the light-stressed, concave, avascular center of the retina where light is focused), we investigated the expression sites of neural stem cell (NSC)-related genes in the monkey retina. Methods: Cynomolgus monkeys were euthanized, and both eyes were then enucleated. Each eye was hemisected near the limbus, and flat-mounted retina samples were then prepared. Using a stereomicroscope, 1-mm x 1-mm blocks of the retina at the fovea, mid-periphery, and extreme periphery were then excised. These samples were used for real-time polymerase chain reaction analysis of the NSC-related gene (nestin, PAX6, and SOX2) expression at each site. Results: Nestin expression was high in the fovea, with a lower expression in the mid-periphery and extreme periphery. No differences in PAX6 gene expression were found in the fovea, mid-periphery, and extreme periphery. SOX2 expression was highest in the extreme periphery, with decreased expression in the mid-periphery and fovea. Conclusions: Our finding that nestin expression was highest in the fovea suggests that foveal retinal cells may have more undifferentiated characteristics that are different from retinal cells at other sites.