Use of iris pigment epithelium to replace retinal pigment epithelium in age-related macular degeneration -: A gene expression analysis

Objective: To determine the gene expression profiles of primary retinal pigment epithelium ( RPE) and iris pigment epithelium ( IPE) using microarrays. Methods: Primary RPE and IPE from 6 human donor eyes were collected, and total RNA was isolated. Differences in gene expression were determined using a human genechip ( human U95Av2 [ 12 600 probes]; Affymetrix Inc, Santa Clara, Calif). Results: Hierarchical cluster analysis differentiated the gene expression profiles of RPE and IPE clusters into 2 distinct groups. A mean +/- SD of 5308 +/- 416 gene probes were expressed in RPE vs 6130 +/- 205 in IPE. Sixty-eight genes were expressed only in RPE; 154 genes were expressed only in IPE. Twenty- two additional genes had greater than 3-fold increased expression in RPE vs IPE, and 147 genes had greater than 3-fold decreased expression in RPE vs IPE. Conclusion: There are major differences in the gene expression profiles of primary RPE vs IPE. Clinical Relevance: The different gene expression profiles of primary RPE vs IPE harvested from the same donor eyes infer that it may be difficult for IPE to replace all aspects of damaged RPE function in transplantation studies.