Decoupling cell growth and product formation in Chinese hamster ovary cells through metabolic control

The development of a strategy for the culture of Chinese hamster ovary (CHO ) cells producing tissue plasminogen activator (t-PA) is investigated. This strategy is based on the replacement of the main carbon source, glucose, b y another compound that is slowly metabolizable, particularly galactose. Th e introduction of this change allows for acute change in cell behavior at v arious levels. Cell growth is stopped after this nutrient shift, and the ce lls can be kept in long-duration culture at a low growth rate and high viab ility as compared with a culture strategy based solely on glucose utilizati on. Moreover, the capability of cells to produce recombinant proteins (t-PA in this work) can be maintained over the entire period of galactose feedin g. From the metabolic point of view, use of a slowly metabolizable carbon s ource (galactose) introduces important changes in the production of lactate , ammonia, and some amino acids. The use of this metabolic shift enables th e generation of biphasic processes, with a first phase with cell growth on glucose and a second stationary phase on galactose, which is particularly s uited to perfusion systems. (C) 2001 John Wiley & Sons, Inc.