High mannose (HM) glycan levels on secreted monoclonal antibodies can be influenced by external factors, including osmolality and copper deficiency, and by intrinsic factors determined by different cell lines. In order to identify the metabolic markers associated with HM glycan levels, metabolomics analysis was performed to assess the changes in the extracellular metabolites of recombinant cell lines at different time points during fed-batch production process. Ornithine was identified as the common metabolic marker influenced by both external and intrinsic factors when eight different medium conditions and eight different cell lines exhibiting different levels of HM were compared. A strong correlation was also observed between HM and mRNA expression levels of arginase 1, an enzyme that catalyzes the conversion of arginine to ornithine. The results from functional validation study showed that the supplementation of ornithine to the culture medium leads to an increased level of HM, while reduced concentration of spermine, a downstream product of ornithine metabolism, leads to a decreased level of HM. Additional metabolic markers correlating with HM glycan levels were identified from eight-cell line comparison analysis. A common feature shared by these identified markers is their previously described roles as contributors of cellular redox regulation.
Keywords: Chinese hamster ovary; Copper; Glycosylation; High mannose; Metabolomics; Ornithine.
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