Analysis of RPE morphometry in human eyes

• Type of Material: Article
• Authors: Shagun K. Bhatia, Emory University; Alia Rashid, Emory University; Micah A. Chrenek, Emory University; Qing Zhang, Emory University; Beau Bruce, Emory University; Michael Klein, Emory University; Jeffrey Boatright, Emory University; Yi Jiang, Georgia State University; Hans Grossniklaus, Emory University; John Nickerson, Emory University
• Language: English
• Date: 2016-07-30
• Publisher: Molecular Vision
• Publication Version: Final Published Version
• Copyright Statement: © 2016 Molecular Vision.
• License: Creative Commons Attribution-NonCommerical-NoDerivs 3.0 Unported
• Final Published Version (URL): http://www.molvis.org/molvis/v22/898/
• Title of Journal or Parent Work: Molecular Vision
• ISSN: 1090-0535
• Volume: 22
• Start Page: 898
• End Page: 916
• Grant/Funding Information: This work was supported by the National Center for Advancing Translational Sciences of the National Institutes of Health under award numbers UL1TR000454 and TL1TR000456.; This research was also supported under the following grants: NIH R01EY016470, R01EY021592, P30EY006360, R01EY0014026, The Katz Foundation, VARR&D I21RX001924, VARR&D C9246C, an internal pilot grant from the Neuroscience Initiative at Emory University, and an unrestricted grant to the Emory Eye Center from Research to Prevent Blindness, Inc.
• Research Categories: Health Sciences, Epidemiology; Biology, Neuroscience; Biology, Cell

Abstract

Purpose: To describe the RPE morphometry of healthy human eyes regarding age and topographic location using modern computational methods with high accuracy and objectivity. We tested whether there were regional and age-related differences in RPE cell area and shape. Methods: Human cadaver donor eyes of varying ages were dissected, and the RPE flatmounts were immunostained for F-actin with AF635-phalloidin, nuclei stained with propidium iodide, and imaged with confocal microscopy. Image analysis was performed using ImageJ (NIH) and CellProfiler software. Quantitative parameters, including cell density, cell area, polygonality of cells, number of neighboring cells, and measures of cell shape, were obtained from these analyses to characterize individual and groups of RPE cells. Measurements were taken from selected areas spanning the length of the temporal retina through the macula and the mid-periphery to the far periphery. Results: Nineteen eyes from 14 Caucasian donors of varying ages ranging from 29 to 80 years were used. Along a horizontal nasal to temporal meridian, there were differences in several cell shape and size characteristics. Generally, the cell area and shape was relatively constant and regular except in the far periphery. In the outer third of the retina, the cell area and shape differed from the inner two-thirds statistically significantly. In the macula and the far periphery, an overall decreasing trend in RPE cell density, percent hexagonal cells, and form factor was observed with increasing age. We also found a trend toward increasing cell area and eccentricity with age in the macula and the far periphery. When individuals were divided into two age groups, <60 years and ≥60 years, there was a higher cell density, lower cell area, lower eccentricity, and higher form factor in the younger group in the macula and the far periphery (p<0.05 for all measurements). No statistically significant differences in RPE morphometry between age groups were found in the mid-periphery. Conclusions: Human cadaver RPE cells differ mainly in area and shape in the outer one third compared to the inner two-thirds of the temporal retina. RPE cells become less dense and larger, lose their typical hexagonal shape, and become more oval with increasing age.