Abstract
PURPOSE: Adult stem cells (SCs) with self-renewal and multilineage potential have been reported upon culturing human retinal pigment epithelial (RPE) cells. The current study aimed to identify the location of SCs in human RPE and to elucidate the age-related changes. METHODS: Peripheral, equatorial, and central RPE cells from donors of three age groups were analyzed for their sphere-forming, clonal, and label-retaining cell properties. Furthermore, native human RPE flatmounts were immunostained for SC and proliferating cell markers. RESULTS: Cells with higher sphere-forming and clonal ability were identified only in young donors (<30 years) and were restricted to the periphery. Upon culturing, cells from peripheral and equatorial regions had the label-retaining cell (LRC) property. With aging, the LRCs were restricted to the periphery and were reduced. In young donors, Ki67 + proliferating cells were not observed in native RPE. However, such cells were observed in the peripheral RPE of older donors correlating with the need for regeneration. The native RPE cells were negative for SC marker expression. CONCLUSION: The above findings highlighted the presence of SCs with the ability to proliferate in the peripheral RPE and a reduction in these functional properties of SCs with aging.