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Effects of Growth Factors on Differentiation of Porcine Lens Epithelial Cells
Hesse Y., Lang G. K., Kampmeier J., Lang G. E.,
Universität Ulm, Augenklinik und Poliklinik (Ulm)
Purpose: Transdifferentiation of lens epithelial cells (LECs) to myofibroblasts is beside cell proliferation one of the mechanisms of secondary cataracts formation. This process is characterized by increased a-smooth muscle actin (a-SMA) expression. This study investigated the influence of bFGF, TGF-b 2, EGF and IGF-1 on the a-SMA expression in porcine LECs.
Methods: Porcine LECs were cultured for 7 days in serum-free medium without or with 1 to 50 ng/ml bFGF, TGF-b 2, EGF or IGF-I and in medium containing 10% fetal bovine serum. Alpha-SMA was detected immunocytochemically with a mouse monoclonal antibody, and the relative numbers of a-SMA-positive cells were calculated. Statistical analysis was performed using Student´s unpaired t-test.
Results: The ratio of a-SMA-positive cells cultured for 7 days in serum-free medium was 36 ± 11.9% (mean ± SD). BFGF significantly reduced this ratio in a dose dependent manner from 42,9 ± 4.1% to 11.2 ± 7.3% at a concentration of 50ng/ml (p<0.0001). EGF reduced the ratio significantly from 39.8 ± 14.8% to 25.1 ± 15.7% (p=0.05) when 50ng/ml were applied. IGF-1 (10ng/ml) reduced the relative numbers of transdifferenciated cells from 27.8 ± 15.4% to 16.8 ± 5.8%, but the reduction was not significant (p=0.0787). TGF-b 2 (50ng/ml) slightly increased the relative number of a-SMA-positive cells from 33.8 ± 13.2% to 44.2 ± 13.8%. However, this increase was not significant (p=0.1202) during a culture period of 7 days. Cells cultured in serum-supplemented medium presented an overall ratio of 11 ± 7.4%.
Conclusion: BFGF and EGF significantly reduced the a-SMA expression of LECs while TGF-b and IGF-1 had no significant effect. These results suggest that bFGF and EGF don´t primarily induce secondary cataract formation by the mechanism of cell transdifferentiation. Supported by Bausteinprojekt P.688.