The RPE is a monolayer of pigmented cells located in the back of the eye between the neural retina and the choroidal blood supply and is critical for normal photoreceptor function. We previously developed and physiologically characterized a human fetal RPE primary culture. The purpose of this project was to examine the miRNA expression profiles of native human fetal RPE and cells grown on Primaria flask and human extracellular matrix coated transwells. ? ? MicroRNAs (miRNAs) regulate a significant portion of the transcriptome. Over 300 vertebrate miRNAs have now been identified and their targets have been predicted to cover approximately 30% of the genome. miRNA expression levels in retina, retinal pigment epithelium (RPE) and choroid of human fetal eyes were analyzed at 10, 16, and 20 weeks of gestation (WG) using quantitative RT-PCR. Duplicates of miRNA profiles from cultured human fetal RPE were highly reproducible by Q-PCR. Approximately 90% of 157 miRNAs examined were present in retina, RPE, and choroid with significantly different abundance. In the same tissue, miRNA expression did not change significantly between 16 and 20 WG. miRNAs enriched in retina, RPE, or choroid were identified. miRNA in cultured hfRPE and native hfRPE were significantly different. Five out of six miRNAs highly enriched in native hfRPE were also enriched in the cultures. Six miRNAs enriched in RPE had more than 800 predicted targets and 60 of them were targets for 2 or 3 of the 6 miRNAs. Anti-miRNAs will be transfected into cultured hfRPE and functional parameters such as tissue resistance will be monitored. In conclusion, miRNAs are extensively expressed in human fetal retina, RPE, and choroid with highly tissue-specific profiles.
