Application of maltose as energy source in protein-free CHO-K1 culture to improve the production of recombinant monoclonal antibody.

Oligosaccharides are generally considered to be un-utilized for growth of mammalian cells because their permeability across the cell membrane is low. However, in our previous study, we discovered that CHO and HEK293 cells consume maltose in culture media without serum and glucose. This is interesting because the transporter for maltose in mammalian cells has not been discovered to-date, and the only animal disaccharide transporter that is recently discovered is a sucrose transporter. The application of oligosaccharides in mammalian cell-based biopharmaceutical manufacturing can be beneficial, because it can theoretically increase carbohydrate content of the culture medium and decrease lactate production. Here, we first determined that specific maltose consumption rate in CHO cells was similar to galactose and fructose at 0.257 ng/cell/day. We then demonstrated that CHO cells can be cultivated with reasonable cell growth using higher maltose concentrations. After which, we evaluated the use of maltose supplementation in the production of a recombinant monoclonal antibody in batch and fed-batch cultures, demonstrating improvements in recombinant monoclonal antibody titer of 15% and 23% respectively. Finally, glycosylation profiles of the antibodies were analyzed.

Evaluation and use of disaccharides as energy source in protein-free mammalian cell cultures.

Mammalian cells are generally considered to be unable to utilize polysaccharides for cell growth because the phospholipid bilayer in the cell membrane has very low permeability to sugars. With the recent discovery of the only known animal disaccharide transporter, a sucrose transporter, we considered the potential use of polysaccharides as energy source, because that can impact biopharmaceutical manufacturing by potentially increasing carbohydrate loading in the culture medium and decreasing lactate accumulation. In this study, we found that mammalian cells can utilize maltose for growth in the absence of glucose and successfully adapted CHO-K1, CHO-DG44 and HEK293 cells to grow in glucose-free, maltose-containing serum-free protein-free media. We then cultivated a non-adapted CHO-K1 producer cell line in media containing both glucose and maltose to show that the cells can utilize maltose in a biphasic manner, that maltose enters the cells, and that maltose utilization only took place in the presence of the cells. This is the first report of a protein-free mammalian cell culture using a disaccharide as energy source.