Functional differentiation and primary metabolism of mouse mammary epithelial cells in extended‐batch and hollow‐fiber culture

Growth, expression of functional differentiation (as characterized by synthesis and secretion of milk proteins), and primary metabolism were studied for a mouse mammary epithelial cell line, COMMA‐1D, in extended‐batch and hollow‐fiber reactor cultures. Batch cultures were performed on Costar polycarbonate membrane inserts, allowing basal and apical exposure to medium. Protein production was induced in both batch and hollow‐fiber cultures in hormonesupplemented medium. In batch cultures, high levels of protein production and secretion were maintained for 18 days. Once differentiation was induced, the rate of deinduction was low, even in medium containing epidermal growth factor (EGF) and serum; cells continued to express and secrete proteins for at least 12 days after prolactin and hydrocortisone were removed. Cells in both batch and hollow‐fiber cultures were highly glycolytic and exhibited low rates of glutaminolysis. In batch culture on membrane inserts, cells showed polarized metabolism between the apical and basal side, maintaining significant gradients of glucose and lactate. Medium hormonal composition and subsequent differentiation affected both glucose uptake and lactate yield for COMMA‐1D in batch culture. © 1992 John Wiley & Sons, Inc.