Hepatocyte Growth Factor Inhibits Myofibroblastic Transformation in RPE Cells

Abstract

Abstract: : Purpose: Retinal pigment epithelial (RPE) cells undergo epithelial to mesenchymal transdifferentiation, with increased expression of smooth muscle actin (SMA), after stimulation with transforming growth factor beta 2 (TGFß2). The aim of this study was to determine if hepatocyte growth factor (HGF) can suppress this myofibroblastic transformation in RPE cells. Methods: Early-passage RPE cells were grown to sub-confluence in complete medium (DMEM, 10% fetal bovine serum (FBS)), then changed to 1% FBS medium or serum-free medium and treated with recombinant human TGFß2 (5ng/ml final concentration) and recombinant human HGF in different concentrations (2.5–60 ng/ml). HGF was added either before the TGFß2 administration or at the same time, and on the first day of treatment only or daily. The cells were incubated for 72 hours after the addition of cytokines before harvesting. SMA expression was assessed by flow cytometry, western blot and immunohistochemistry. Results: A single HGF treatment, regardless if given before or at the same time as TGFß2 did not alter the SMA production in RPE cells, even in high doses. However, when administered on a daily basis during the 3 day incubation with TGFß2, HGF significantly reduced the SMA content in the RPE cells. Conclusion: HGF, when administered continuously, can suppress TGFß2 induced SMA production in vitro; however, a single HGF treatment does not significantly alter this TGFß2 induced effect. This finding suggests that continuous or long term treatment with HGF should be investigated for its potential to prevent mesenchymal transdifferentiation of RPE cells in vivo.

Keywords: retinal pigment epithelium • growth factors/growth factor receptors • cytokines/chemokines