N. Ibaraki et al., A STUDY OF GROWTH-FACTOR RECEPTORS IN HUMAN LENS EPITHELIAL-CELLS ANDTHEIR RELATIONSHIP TO FIBER DIFFERENTIATION, Experimental Eye Research, 63(6), 1996, pp. 683-692
Recent studies have demonstrated that several growth factors enhance f
iber differentiation in cultured human lens epithelial (HLE) cells in
early passages. However, these effects gradually decrease in cells of
later passages. The purpose of this investigation is to test the hypot
hesis that the decreasing effect of growth factors on fiber differenti
ation in later passages may be due to a decrease or the inactivation o
f growth factor receptors as a function of serial subcultures. Specime
ns of HLE cells were obtained from infants. First through to fourth pa
ssage cells were treated with 10 ng ml(-1) of epidermal growth factor,
basic fibroblast growth factor or insulin-like growth factor-I. Fiber
differentiation was determined from spontaneous lentoid formation by
phase-contrast and transmission electron microscopy. Growth factor bin
ding to the receptor on the cell surface was determined by transmissio
n electron microscopy using the conjugates of colloidal gold and growt
h factors, and the number of receptors on the cell surface were also q
uantified by immunocytochemistry. Spontaneous lentoid formation was en
hanced by all of the growth factors studied in the first passage. Howe
ver, in the second and third passage only double layering of cells wit
hout characteristic fiber differentiation was observed while in the fo
urth passage, growth factors had no effect on differentiation. The num
ber of growth factor bindings as well as the number of growth factor r
eceptors gradually decreased with the number of passages. The loss of
effect of growth factors on fiber differentiation with increasing numb
er of passages correlated with the decrease in receptor number. (C) 19
96 Academic Press Limited