KERATINOCYTE GROWTH-FACTOR AND ACIDIC FIBROBLAST GROWTH-FACTOR ARE MITOGENS FOR PRIMARY CULTURES OF MAMMARY EPITHELIUM

Mammary epithelial cells derived from the entire mammary parenchyma or only end buds were isolated by collagenase digestion of mammary gland s from virgin mice. Cells were cultured within collagen gels in serum- free medium containing insulin. Keratinocyte growth factor (KGF or FGF -7) and acidic fibroblast growth factor (aFGF or FGF-1) stimulated mul tifold proliferation when added alone to this medium. Growth occurred as three-dimensional colonies within the collagen gel matrix. KGF stim ulated growth was unaffected by adding heparin. Conversely, multifold growth stimulation by acidic FGF required heparin. Since end buds are the actively proliferating cell population of ductal glands, organ cul tures of these structures were prepared. KGF stimulated H-3-thymidine incorporation in these end buds in the absence and presence of epiderm al growth factor. These data suggest that acidic FGF and KGF may repre sent in vivo stromal factors capable of regulating mammary gland devel opment. (C) 1994 Academic Press, Inc.