title: Effects of copper on CHO cells: cellular requirements and product quality considerations.
abstract: Recent reports highlight the impact of copper on lactate metabolism: CHO cell cultures with higher initial copper levels shift to net lactate consumption and yield lower final lactate and higher titers. These studies investigated the effects of copper on metabolite and transcript profiles, but did not measure in detail the dependences of cell culture performance and product quality on copper concentrations. To more thoroughly map these dependences, we explored the effects of various copper treatments on four recombinant CHO cell lines. In the first cell line, when extracellular copper remained above the limit of detection (LOD), cultures shifted to net lactate consumption and yielded comparable performances irrespective of the differences in copper levels; when extracellular copper dropped below LOD (∼13 nM), cultures failed to shift to net lactate consumption, and yielded significantly lower product titers. Across the four cell lines, the ability to grow and consume lactate seemed to depend on the presence of a minimum level of copper, beyond which there were no further gains in culture performance. Although this minimum cellular copper requirement could not be directly quantified, we estimated its probable range for the first cell line by applying several assumptions. Even when different copper concentrations did not affect cell culture performance, they affected product quality profiles: higher initial copper concentrations increased the basic variants in the recombinant IgG1 products. Therefore, in optimizing chemically defined media, it is important to select a copper concentration that is adequate and achieves desired product quality attributes.
authors.affiliation: Early Stage Cell Culture, Bioprocess Development, Genentech, 1 DNA Way, South San Francisco, CA, 94080.
authors.forename: Inn H
authors.initials: IH
authors.lastname: Yuk
authors.forename: Stephen
authors.initials: S
authors.lastname: Russell
authors.forename: Yun
authors.initials: Y
authors.lastname: Tang
authors.forename: Wei-Ting
authors.initials: WT
authors.lastname: Hsu
authors.forename: Jacob B
authors.initials: JB
authors.lastname: Mauger
authors.forename: Rigzen P S
authors.initials: RP
authors.lastname: Aulakh
authors.forename: Jun
authors.initials: J
authors.lastname: Luo
authors.forename: Martin
authors.initials: M
authors.lastname: Gawlitzek
authors.forename: John C
authors.initials: JC
authors.lastname: Joly
mesh_terms: D000818:Animals; D016466:CHO Cells; D018929:Cell Culture Techniques / Q000379:methods*; D049109:Cell Proliferation / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects*; D003300:Copper / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D006224:Cricetinae; D003412:Cricetulus; D003470:Culture Media / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000378:metabolism
chemical_list: D003470:Culture Media; D019344:Lactic Acid; D003300:Copper
keywords: CHO cells; basic variants; copper; lactate; product quality