title: Feed development for fed-batch CHO production process by semisteady state analysis.
abstract: Semisteady state cultures are useful for studying cell physiology and facilitating media development. Two semisteady states with a viable cell density of 5.5 million cells/mL were obtained in CHO cell cultures and compared with a fed-batch mode control. In the first semisteady state, the culture was maintained at 5 mM glucose and 0.5 mM glutamine. The second condition had threefold higher concentrations of both nutrients, which led to a 10% increase in lactate production, a 78% increase in ammonia production, and a 30% reduction in cell growth rate. The differences between the two semisteady states indicate that maintaining relatively low levels of glucose and glutamine can reduce the production of lactate and ammonia. Specific amino acid production and consumption indicated further metabolic differences between the two semisteady states and fed-batch mode. The results from this experiment shed light in the feeding strategy for a fed-batch process and feed medium enhancement. The fed-batch process utilizes a feeding strategy whereby the feed added was based on glucose levels in the bioreactor. To evaluate if a fixed feed strategy would improve robustness and process consistency, two alternative feeding strategies were implemented. A constant volume feed of 30% or 40% of the initial culture volume fed over the course of cell culture was evaluated. The results indicate that a constant volumetric-based feed can be more beneficial than a glucose-based feeding strategy. This study demonstrated the applicability of analyzing CHO cultures in semisteady state for feed enhancement and continuous process improvement.
authors.affiliation: Process Sciences Upstream, Technical Operations, Bristol-Myers Squibb Company, Syracuse, NY 13221, USA.
authors.forename: Sarwat F
authors.initials: SF
authors.lastname: Khattak
authors.forename: Zizhuo
authors.initials: Z
authors.lastname: Xing
authors.forename: Brian
authors.initials: B
authors.lastname: Kenty
authors.forename: Inna
authors.initials: I
authors.lastname: Koyrakh
authors.forename: Zheng Jian
authors.initials: ZJ
authors.lastname: Li
mesh_terms: D000641:Ammonia / Q000378:metabolism; D000818:Animals; D019149:Bioreactors; D016466:CHO Cells / Q000166:cytology / Q000378:metabolism*; D002452:Cell Count; D018929:Cell Culture Techniques / Q000379:methods*; D002470:Cell Survival; D006224:Cricetinae; D003412:Cricetulus; D003470:Culture Media; D005947:Glucose / Q000378:metabolism; D005973:Glutamine / Q000378:metabolism; D019344:Lactic Acid / Q000378:metabolism
chemical_list: D003470:Culture Media; D005973:Glutamine; D019344:Lactic Acid; D000641:Ammonia; D005947:Glucose