title: More similar than different: Host cell protein production using three null CHO cell lines.
abstract: To understand the diversity in the cell culture harvest (i.e., feedstock) provided for downstream processing, we compared host cell protein (HCP) profiles using three Chinese Hamster Ovary (CHO) cell lines in null runs which did not generate any recombinant product. Despite differences in CHO lineage, upstream process, and culture performance, the cell lines yielded similar cell-specific productivities for immunogenic HCPs. To compare the dynamics of HCP production, we searched for correlations between the time-course profiles of HCP (as measured by multi-analyte ELISA) and those of two intracellular HCP species, phospholipase B-like 2 (PLBL2) and lactate dehydrogenase (LDH). Across the cell lines, proteins in the day 14 supernatants analyzed by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) showed different spot patterns. However, subsequent analysis by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) indicated otherwise: the total number of peptides and proteins identified were comparable, and 80% of the top 1,000 proteins identified were common to all three lines. Finally, to assess the impact of culture viability on extracellular HCP profiles, we analyzed supernatants from a cell line whose viability dropped after day 10. The amounts of HCP and PLBL2 (quantified by their respective ELISAs) as well as the numbers and major populations of HCPs (identified by LC-MS/MS) were similar across days 10, 14, and 17, during which viabilities declined from ∼80% to <20% and extracellular LDH levels increased several-fold. Our findings indicate that the CHO-derived HCPs in the feedstock for downstream processing may not be as diverse across cell lines and upstream processes, or change as dramatically upon viability decline as originally expected. In addition, our findings show that high density CHO cultures (>10(7) cells/mL)-operated in fed-batch mode and exhibiting high viabilities (>70%) throughout the culture duration-can accumulate a considerable amount of immunogenic HCP (∼1-2 g/L) in the extracellular environment at the time of harvest (day 14). This work also demonstrates the potential of using LC-MS/MS to overcome the limitations associated with ELISA and 2D-PAGE for HCP analysis.
authors.affiliation: Early Stage Cell Culture, Genentech, 1 DNA Way, South San Francisco, California, 94080. inn@gene.com.
authors.forename: Inn H
authors.initials: IH
authors.lastname: Yuk
authors.affiliation: Protein Analytical Chemistry, Genentech, 1 DNA Way, South San Francisco, California, 94080.
authors.forename: Julie
authors.initials: J
authors.lastname: Nishihara
authors.affiliation: Protein Analytical Chemistry, Genentech, 1 DNA Way, South San Francisco, California, 94080.
authors.forename: Donald
authors.initials: D
authors.lastname: Walker
authors.affiliation: Early Stage Cell Culture, Genentech, 1 DNA Way, South San Francisco, California, 94080.
authors.forename: Eric
authors.initials: E
authors.lastname: Huang
authors.affiliation: Analytical Operations, Genentech, 1 DNA Way, South San Francisco, California, 94080.
authors.forename: Feny
authors.initials: F
authors.lastname: Gunawan
authors.affiliation: Early Stage Cell Culture, Genentech, 1 DNA Way, South San Francisco, California, 94080.
authors.forename: Jayashree
authors.initials: J
authors.lastname: Subramanian
authors.affiliation: Early Stage Cell Culture, Genentech, 1 DNA Way, South San Francisco, California, 94080.
authors.forename: Abigail F J
authors.initials: AF
authors.lastname: Pynn
authors.affiliation: Protein Analytical Chemistry, Genentech, 1 DNA Way, South San Francisco, California, 94080.
authors.forename: X Christopher
authors.initials: XC
authors.lastname: Yu
authors.affiliation: Protein Analytical Chemistry, Genentech, 1 DNA Way, South San Francisco, California, 94080.
authors.forename: Judith
authors.initials: J
authors.lastname: Zhu-Shimoni
authors.affiliation: Analytical Operations, Genentech, 1 DNA Way, South San Francisco, California, 94080.
authors.forename: Martin
authors.initials: M
authors.lastname: Vanderlaan
authors.affiliation: Analytical Operations, Genentech, 1 DNA Way, South San Francisco, California, 94080.
authors.forename: Denise C
authors.initials: DC
authors.lastname: Krawitz
mesh_terms: D000818:Animals; D016466:CHO Cells; D049109:Cell Proliferation; D002470:Cell Survival; D002853:Chromatography, Liquid; D003412:Cricetulus; D015180:Electrophoresis, Gel, Two-Dimensional; D004797:Enzyme-Linked Immunosorbent Assay; D007770:L-Lactate Dehydrogenase / Q000032:analysis; D008245:Lysophospholipase / Q000032:analysis; D020543:Proteome / Q000032:analysis*; D053719:Tandem Mass Spectrometry; D013997:Time Factors
chemical_list: D020543:Proteome; D007770:L-Lactate Dehydrogenase; D008245:Lysophospholipase
keywords: CHO host cell protein; ELISA; LC-MS/MS; PLBL2; orthogonal methods; proteomics