Localization of pigment epithelium derived factor (PEDF) in developing andadult human ocular tissues

PURPOSE: To localize pigment epithelium-derived factor (PEDF) in developing and adult human ocular tissues. METHODS: PEDF was localized in fetal and adult eyes by immunofluorescence w ith a polyclonal antibody (pAb) against amino acids 327-343 of PEDF, or a m onoclonal antibody (mAb) against the C-terminal 155 amino acids of PEDF. Sp ecificity of the antibodies was documented by Western blotting. PEDF mRNA w as localized in adult retina by in situ hybridization. RESULTS: In developing retinas (7.4 to 21.5 fetal weeks, Fwks), pAb anti-PE DF labeled retinal pigment epithelium (RPE) granules, developing cones, som e neuroblasts and many cells in the ganglion cell layer (GCL). In adult ret inas, pAb anti-PEDF labeled rod and cone cytoplasm and nuclei of rods but n ot cones. Cells in the INL and GCL, choroid, corneal epithelium and endothe lium, and ciliary body were also pAb PEDF-positive. Preadsorption of pAb an ti-PEDF with the immunizing peptide blocked specific labeling in retina and other tissues, except for photoreceptor outer segments. In agreement with the immunolocalization with pAb anti-PEDF, in situ hybridization revealed P EDF mRNA in the RPE, photoreceptors, inner nuclear layer cells and ganglion cells in adult retina. In developing retinas 18 Fwks and older, and in adu lt retinas, mAb anti-PEDF labeled the interphotoreceptor matrix (IPM). West ern blots of retina, cornea, and ciliary body/iris with pAb anti-PEDF produ ced several bands at about 46 kDa. With mAb anti-PEDF, retina produced one band at about 46 kDa; cornea and ciliary body/iris had several bands at abo ut 46 kDa. CONCLUSIONS: PEDF, originally reported as a product of RPE cells, is presen t in photoreceptors and inner retinal cell types in developing and adult hu man eyes. Photoreceptors and RPE may secrete PEDF into the IPM.