Nucleotide sugar precursor feeding strategy to enhance sialylation of albumin-erythropoietin in CHO cell cultures

Chinese hamster ovary (CHO) cells have been widely used for the production of glycoproteins due to various advantages such as high productivity, ease of genetic manipulation, adaptability to serum-free media, and human-like glycosylation. Glycosylation, which occurs sequentially using nucleotide sugars as donor substrates, can affect the therapeutic function of glycoproteins. Terminal sialic acid residues of N-glycans play an important role in determining in vivo half-life of glycoproteins. Therefore, various strategies have been developed to enhance sialylation of glycoproteins. In this study, a nucleotide sugar precursor feeding strategy was optimized to increase sialic acid content of albumin-erythropoietin (Alb-EPO). Glucosamine, galactose, and N-acetylinannosamine were added to CHO cell cultures in lag (day 0) or exponential phase (day 3). Central composite design and response surface methodology were used to evaluate the effects of nucleotide sugar precursors on cell growth, titer, and sialic acid content. For the exponential feeding strategy, culture performance was not altered by addition of optimal precursor concentrations, whereas sialic acid contents increased 1.43-fold compared to the control. Consequently, our nucleotide sugar precursor feeding strategy can provide an efficient culture process for production of highly sialylated glycans on Alb-EPO.