Abstract
Purpose: :
To date several studies have used IPE transplanted into the subretinal space to remove diseased or damaged native RPE. Herein we compare the proteomes of primary human RPE and IPE cells.
Methods: :
Human IPE and RPE were harvested from three fresh (death–to–harvest time <24 hrs) donors (ages: 28 and 69, 70). Cells were homogenized and 30 µg of cellular protein was extracted. Proteins were focused using pH 3–10 7.7cm IEF strips and further separated in the second dimension on 4–12% Bis–Tris gels. Sypro Ruby staining spots of interest were cut and peptide analysis was done using mass spectrometry. Quantification of protein expressions between IPE and RPE were done using Phoretix Expression 2D software.
Results: :
Only 17.4% of the human RPE proteome was expressed by IPE cells without any significant quantitative differences. These proteins correspond to 19.3% of the whole IPE proteome. However, 34.2% of the proteins expressed by human RPE were not produced by IPE cells, in addition to 28.9% that were produced two–folds lesser amounts. Similarly, 27.4% of the proteins expressed by IPE were not a part of the RPE proteome. Some of the proteins that are not a part of the primary human IPE proteome include: VEGF 121 precursor, elastase–3, vitamin D receptor, collagen type 9A1, Traf2–CD40 receptor complex, synaptotagmin I, immunoglobulin heavy chains, and peroxisome receptor 1.
Conclusions: :
IPE and RPE cells proteomes differ significantly. Replacing RPE cells with IPE may require their adaptational plasticity in the subretinal space to carry out RPE–related cellular functions. The ability of IPE to express RPE–specific proteins after transplantation into the <!–– within the ––>subretinal milieu is not known yet.
Keywords: transplantation • retinal pigment epithelium • proteomics