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G.E. Lang, A. Uecker, G.K. Lang, H. Deissler; Immortalized BREC Transdifferentiate to Mesenchymal Cells in the Presence of TGFbeta2 . Invest. Ophthalmol. Vis. Sci. 2005;46(13):4179.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Diabetic retinopathy (DR) is a major complication of diabetes mellitus and the main reason for blindness in the western world. Loss of pericytes which control poliferation of retinal endothelial cells in vivo has been discussed as an early event in the development of DR. Transforming growth factor (TGF)–ß2 promotes transdifferentiation of macrovascular endothelial cells to α–smooth–muscle–actin (α–SMA) expressing (mesenchymal) cells. We describe here that immortalized bovine retinal endothelial cells (iBREC) transdifferentiate partly to α–SMA expressing cells. Methods: The cell line iBREC has recently been established in our laboratory by transduction of the cDNA for hTERT into primary BRECs. Cells were grown on fibronectin–coated slides for several days in low–serum medium with 5 ng/ml VEGF or 1– 10 ng/ml TGF–ß2. Cells were immunostained for the expression of the EC–marker von Willebrand factor or the pericyte marker α–SMA, respectively. In addition, cells treated with TGF–ß2 for 14 days were seeded on slides and then incubated with VEGF or TGF–ß2 respectively for several days. Results: iBREC lost their cobble–stone morphology after 2–day incubation with 1 or 10 ng/ml TGF–ß2. About 10% of the cells adopted a pericyte–like morpholgy and stronlgly expressed the pericyte marker α–SMA after 4 days. α–SMA–expressing pericyte–like cells did not appear in colonies but in isolated spots indicating conversion of EC to pericyte–like cells rather than proliferation of pericyte–contamination. In addition, immunostaining of untreated iBREC–cultures never revealed any α–SMA–expressing cells. Induction of α–SMA by TGF–ß2 was not reversible throughout 7 days. Loss of cobble–stone morphology of iBREC was not observed after treatment with 5 ng/ml VEGF, bFGF, and IGF–1. Conclusions: TGF–ß2 treatment of iBREC leads to a permanent alteration of the cellular phenotype. Our results suggest that iBREC can transdifferentiate to pericyte–like cells. This might have an impact on the understanding of the development of DR.
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