Abstract
Purpose :
We have previously identified the presence of proliferating cells in the peripheral region of native human Retinal Pigment Epithelium (RPE) highlighting the probable presence of adult stem cells. This study aims to identify the region of RPE encompassing the cells with functional characteristics of adult stem cells upon culturing and their age-related changes.
Methods :
Donor eyes from three different age groups: <30, 30-60 and >60 years (n=5/group) were obtained from the eye banks of Aravind Eye Care System. Cells from either total or from three regions of RPE (Peripheral, Equatorial and Central) were isolated mechanically by brushing off the cells, trypsinised and subjected to sphere formation assay, clonal analysis and BrdU label retaining assay (followed by immunostaining for KLF4/c-MYC).
Results :
Analysis of different regions of RPE confirmed that cells with the ability to form spheres and clones were restricted to the peripheral region, while the label-retaining cells (LRCs) expressing stem cell markers KLF4 and c-MYC were identified both in the peripheral and equatorial regions. A decline in the number of cells with these functional properties was observed with ageing in the peripheral RPE: i) Sphere forming ability (<30 years=2.35±0.19%; >30 years= 0%), ii) Clone forming ability (<30 years=23.13±2.55%, 30-60 years=11.62±2.25%, >60 years=2.41±1.51%) and iii) Label retaining property (<30 years=11.5±3.95%, 30-60 years=7.3±0.76%, >60 years=1.5±0.71%). LRCs in the equatorial region were completely lost with ageing (<30 years=4.25±0.29%, >30 years= 0%). The central RPE cells did not express any of the functional characteristics of adult stem cells.
Conclusions :
The results indicated that the adult stem cells are located in the peripheral RPE. With ageing, a reduction in the function of RPE stem cells was observed. Further studies are essential to elucidate whether this reduction is associated with the pathogenesis of age-related macular degeneration.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.