[Effect of growth factors on the differentiation of porcine lens epithelial cells].
BACKGROUND
Besides cell proliferation, transdifferentiation of lens epithelial cells (LECs) to myofibroblasts is one of the mechanisms of secondary cataract formation. This process is characterized by increased expression of alpha-smooth muscle actin (alpha-SMA). This study investigated the influence of bFGF, TGF-beta2, EGF and IGF-1 on the expression of alpha-SMA 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-beta2, EGF or IGF-I. Alpha-SMA was detected immunocytochemically with a mouse monoclonal antibody, and the relative numbers of alpha-SMA-positive cells were calculated. Statistical analysis was performed using Student's unpaired t-test.


RESULTS
The ratio of alpha-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 to 11.2 +/- 7.3 % at a concentration of 50 ng/ml (p < 0.0001). EGF reduced the ratio significantly to 25.1 +/- 15.7 % (p = 0.05) when 50 ng/ml were applied. IGF-1 (10 ng/ml) reduced the relative numbers of transdifferentiated cells to 16.8 +/- 5.8 %, but the reduction was not statistically significant (p = 0.0787). TGF-beta2 (50 ng/ml) slightly increased the relative number of alpha-SMA-positive cells to 44.2 +/- 13.8 %. However, this increase was not significant (p = 0.1202) during a culture period of 7 days.


CONCLUSIONS
BFGF and EGF significantly reduced the expression of alpha-SMA by LECs while TGF-beta and IGF-1 had no statistically significant effect. These results suggest that bFGF and EGF do not primarily induce secondary cataract formation by the mechanism of cell transdifferentiation.
Jong-Hesse
Y De
YD
Universitäts-Augenklinik, Prittwitzstr. 43, 89075 Ulm.
Lang
G K
GK
Kampmeier
J
J
Lang
G E
GE
D000199:Actins / Q000378:metabolism*; D000818:Animals; D002386:Cataract / Q000473:pathology / Q000503:physiopathology*; D002452:Cell Count; D002454:Cell Differentiation / Q000502:physiology*; D002455:Cell Division / Q000502:physiology*; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000473:pathology / Q000502:physiology*; D016222:Fibroblast Growth Factor 2 / Q000502:physiology; D006133:Growth Substances / Q000502:physiology*; D066298:In Vitro Techniques; D007334:Insulin-Like Growth Factor I / Q000502:physiology; D007908:Lens, Crystalline / Q000473:pathology / Q000503:physiopathology*; D008856:Microscopy, Fluorescence; D032390:Myoblasts, Smooth Muscle / Q000473:pathology / Q000502:physiology*; D013552:Swine; D016212:Transforming Growth Factor beta / Q000502:physiology
D000199:Actins; D006133:Growth Substances; D016212:Transforming Growth Factor beta; D016222:Fibroblast Growth Factor 2; D007334:Insulin-Like Growth Factor I