Feeding strategy for shifting lactate metabolism in CHO cell cultures through supplementation of metal ion cofactors of cytochrome c oxidase

초록

In CHO cell cultures, lactate shows negative effects on cell culture performance and quality of recombinant proteins. To overcome these adverse effects, various medium additives were used for the regulation of lactate metabolism. It has been also known that lactate consumption is correlated with oxidative metabolism in the mitochondria. Copper (Cu), zinc (Zn), and magnesium (Mg) ions are multiple metal ion cofactors of cytochrome c oxidase, which is the key enzyme in an electron transport chain for oxidative phosphorylation. These metal ions can switch to lactate metabolism through the activation of oxidative phosphorylation with ATP production. In this study, Cu, Zn, and Mg were added for shifting the lactate metabolism of CHO cells producing albumin-erythropoietin (Alb-EPO). Optimization of feeding strategy was performed by using a simplex lattice design. Supplementation of 20.6 mg/L Cu and 9.3 mg/L Mg reduced lactate concentration to minimum level with the highest viable cell density and Alb-EPO titer. Production of ATP was increased up to 1.5-fold and mitochondrial membrane potential was 20% higher than that of control. Furthermore, sialylated glycans of Alb-EPO were significantly increased in the medium containing metal ions. In conclusion, it was found that the feeding strategy of metal ions led to shift in lactate metabolism and improved cell culture performance.