A method of producing a polypeptide in fed batch
cell culture is provided which involves an
initial cell growth phase and a distinct production phase. In the initial growth stage, animal cells having
nucleic acid encoding the polypeptide are cultured at a starting osmolality of about 280-330 mOsm in the presence of a concentration of glucose controlled throughout the culturing to be within a range between about 0.01 and 1 g / L. This is followed by a production phase, where the cultured animal cells of the
growth phase are inoculated at a
cell seed density of at least 1.0×106 cells / mL and the cells are cultured at a starting osmolarity of about 400-600 mOsm in the presence of a concentration of glucose controlled throughout the culturing to be within a range between about 0.01 and 1 g / L. Preferably, the
glutamine concentration in the
cell culture medium is simultaneously controlled in order to curtail production of
lactic acid and
ammonia which result from unnecessarily high
glutamine concentrations. During the
growth phase, production of potentially detrimental
metabolic waste products, such as
lactic acid, is controlled thereby curtailing the increase of osmolality due to accumulation and
neutralization of waste products. Thus, the
cell growth can be improved. In the production phase, the
cell culture conditions are modified in order to arrest or reduce
cell growth and thereby direct
nutrient utilization toward production, as opposed to
cell growth. Overall, it is intended that the method results in an improvement in specific productivity, reduction in production run times and / or an increase in final product concentration.