The impact of microcarrier culture optimization on the glycosylation profile of a monoclonal antibody

Microcarriers are widely used for the large-scale culture of attachment-dependent cells with increased cell densities and, ultimately, higher product yield. In these processes, the specific culture conditions can affect the quality of the product, which is closely related to its glycosylation pattern. Furthermore, the lack of studies in the area reinforces the need to better understand the effects of microcarrier culture in product glycosylation. Consequently, in this work, the glycosylation profile of a monoclonal antibody (mAb) produced by adherent CHO-K1 cells grown in Cytodex 3 was evaluated under different conditions, and compared to that obtained of typical adherent cultures. It was found that microcarrier cultures result in a glycosylation profile with different characteristics from T-flask cultures, with a general increase in galactosylation and decrease in fucosylation levels, both with a potentially positive impact on mAb activity. Sialylation also varied but without a general tendency. This study then showed that the specific culture conditions used in microcarrier culture influence the mAb glycan profile, and each functional element (galactose, core fucose, sialic acid) is independently affected by these conditions. In particular, great reductions of fucosylation (from 79 to 55%) were obtained when using half volume at inoculation, and notable decreases in sialylation (from 23 to 2%) and glycoform heterogeneity (from 20 to 11 glycoforms) were observed for shake flask culture, potentially associated with the improved cell densities achieved in these culture vessels.