Abstract
Abstract: :
Purpose: Successful cellular transplantation in age–related macular degeneration (AMD) and other disorders requires identification and use of the optimal cell source, as well as modification or replacement of damaged Bruch’s membrane. Iris pigment epithelium (IPE) has been used in transplantation studies to replace damaged retinal pigment epithelium (RPE), and a systematic comparison on the properties of these 2 cell types is thus important. Herein we use DNA microarray analysis to determine the gene expression profile of IPE and RPE from the same donor human eye. Methods: Primary RPE and IPE from the same human donors (age: 63, 75 and 85 years) were collected within 48 hours of death and total RNA was isolated. First and second strand cDNA were synthesized with a T7–(dT)24 oligomer for priming. Biotin–labeled antisense cRNA was produced by in vitro transcription. Target hybridization, washing, staining and scanning probe arrays were done following an Affymetrix GeneChip Expression Analysis Manual. Affymetrix Microarray Suite 5.0 and Genesis 1.30 software were used for data analysis. Results: Hierarchic clustering analysis demonstrates that the gene expression profile of the adult RPE and IPE cluster into two distinct groups with no discernable overlap. The expression of 4769 genes (out of 12,600 genes on microarray Human 95UA chip) was detected in RPE cells, in comparison to expression of 6366 genes in adult IPE cells from all 3 human donor eyes. Among these 4595 genes are expressed in both groups. There are 52 genes expressed only in RPE but not detected in IPE, including genes known to be important for RPE function such as a retinol dehydrogenase, angiopoietin 1, an RPE–derived rhodopsin homolog, S–antigen, recoverin, beta–8 integrin, and a transcriptional activator of the c–fos promoter. Numerous genes were expressed only in IPE but not RPE. Conclusions: There are major differences in the gene expression profile of primary RPE vs. IPE harvested from the same donor eye, and some genes known to be critical for RPE function are not expressed within IPE. Our study suggests that genetic modifications maybe necessary if IPE is used to replace damaged human RPE. Future experiments will be directed at determining the effects of the subretinal microenvironment on IPE and RPE gene expression.
Keywords: retinal pigment epithelium • Bruch's membrane • transplantation