MICROPATTERNED IMMOBILIZATION OF EPIDERMAL GROWTH-FACTOR TO REGULATE CELL-FUNCTION

Photoreactive epidermal growth factor (EGF) was synthesized by conjuga ting mouse EGF with photoreactive polyallylamine, which was synthesize d by the coupling reaction of polyallylamine with N-[4-(azidobenzoyl)o xy]succinimide. The EGF derivative was pattern-immobilized onto a poly styrene plate by UV irradiation in the presence of a photomask in a pr escribed micropattern. The patterned immobilization of EGF on the poly styrene plate was confirmed by immunostaining with anti-EGF antibody. Chinese hamster ovary (CHO) cells overexpressing EGF receptors were cu ltured on the micropatterned plate. The phosphorylated tyrosine residu es of signal proteins, including EGF receptors, were detected only in the cells adhered in the EGF-immobilized area, and cell growth was obs erved only in the EGF-immobilized area. The cells growing in the EGF-i mmobilized area were partially stained by anti-phosphotyrosine antibod y, when the area of EGF immobilization was smaller than the cell. The partial staining of activated proteins indicates that immobilization o f EGF inhibited the free lateral diffusion and internalization of the activated EGF-EGF receptor complex. The enhanced cell growth is due to juxtacrine stimulation realized by immobilized EGF.