Histologic Cell Shape Descriptors for the Retinal Pigment Epithelium in Age-Related Macular Degeneration: A Comparison to Unaffected Eyes

Abstract

Purpose Phenotype alterations of the retinal pigment epithelium (RPE) are a main characteristic of age-related macular degeneration (AMD). Individual RPE cell shape descriptors may help to delineate healthy from AMD-affected cells in early disease stages. Methods Twenty-two human RPE flatmounts (7 eyes with AMD [early, 3; geographic atrophy, 1; neovascular, 3); 15 unaffected eyes [8 aged ≤51 years; 7 aged >80 years)] were imaged at the fovea, perifovea, and near periphery (predefined sample locations) using a laser-scanning confocal fluorescence microscope. RPE cell boundaries were manually marked with computer assistance. For each cell, 11 shape descriptors were calculated and correlated with donor age, cell autofluorescence (AF) intensity, and retinal location. Statistical analysis was performed using an ensemble classifier based on logistic regression. Results In AMD, RPE was altered at all locations (most pronounced at the fovea), with area, solidity, and form factor being the most discriminatory descriptors. In the unaffected macula, aging had no significant effect on cell shape factors; however, with increasing distance to the fovea, area, solidity, and convexity increased while form factor decreased. Reduced AF in AMD was significantly associated with decreased roundness and solidity. Conclusions AMD results in an altered RPE with enlarged and deformed cells that could precede clinically visible lesions and thus serve as early biomarkers for AMD onset. Our data may also help guide the interpretation of RPE morphology in in vivo studies utilizing high-resolution single-cell imaging. Translational Relevance Our histologic RPE cell shape data have the ability to identify robust biomarkers for the early detection of AMD-affected cells, which also could serve as a basis for automated segmentation of RPE sheets.

TNFα induced by DNA-sensing in macrophage compromises retinal pigment epithelial (RPE) barrier function

“…2 D,E), consistent with our TER observations. Measurement of morphological parameters revealed a significant decrease in cellular roundness and form factor, two widely used RPE morphometric parameters 19 – 21 , following DNA treatment. Interestingly, these changes were associated with re-organization of RPE tight-functions with jagged and zigzag redistribution of ZO-1 (Fig.…”

Fluorescence Lifetime and Spectral Characteristics of Subretinal Drusenoid Deposits and Their Predictive Value for Progression of Age-Related Macular Degeneration

“…4 E). Finally, RPE dysmorphia (rounding, stacking, anterior migration), also seen in AMD, 41 can cause hyperautofluorescence because of increased pathlength of light through cells with fluorophores. 21 , 22 , 42 , 43 Although we cannot exclude spectral filter effects by SDD or photopigments (or their absence) affecting apparent RPE fluorescence, these effects should alter spectra (PEW) but not lifetimes.…”

Efficient and Consistent Generation of Retinal Pigment Epithelium/Choroid Flatmounts from Human Eyes for Histological Analysis

“…Despite this limitation, REShAPE was specifically trained to recognize and segment RPE cell borders and performs better than other existing methods, such as Voronoi 8 and CellProfiler 9 segmentation of RPE cells. Moreover, compared to manual segmentation 10 , REShAPE provides the advantage of analyzing large images quickly (~130,000 pixels x 130,000 pixels were tested). In conclusion, this dissection method is highly reproducible and can be easily extended to other animal models.…”