Quantification of retinal pigment epithelial phenotypic variation using laser scanning cytometry

Area of Science:

• Ophthalmology
• Cell Biology
• Biotechnology

Background:

• Phenotypic variation in retinal pigment epithelium (RPE) protein expression (variegation) is crucial for understanding RPE-associated pathologies.
• Existing quantitative methods for single-cell analysis are limited, especially given pigment and lipofuscin interference in RPE cells.

Purpose of the Study:

• To evaluate the utility of laser scanning cytometry (LSC) for quantifying protein expression variegation in single RPE cells.
• To assess age-related changes in RPE protein expression using LSC.

Main Methods:

• Applied LSC to paraffin-embedded mouse and human eye sections.
• Used DAPI for nuclear identification, anti-RPE65 antibody for RPE cell identification, and anti-MnSOD antibody for MnSOD quantification.
• Processed data using WinCyte software, analyzing Mean Fluorescence Intensity (MFI), Coefficient of Variation (CV), and percentage of labeled cells.

Main Results:

• Successfully identified and quantified RPE cells and MnSOD expression in both mouse and human eye sections.
• Overcame background interference from pigment and autofluorescence by optimizing antibody concentrations.
• Observed age-related changes in MFI, CV, and the percentage of RPE cells expressing MnSOD.

Conclusions:

• LSC effectively quantifies protein-level gene expression variability in RPE cells.
• Analysis of MFI and CV changes can distinguish between transcriptional changes and alterations in chromatin structure.
• Age-related variegation in RPE cells appears primarily driven by changes in chromatin structure.