中国生物工程杂志

Fed-batch culture has been one of main bioprocesses for monoclonal antibody (mAb) production by Chinese hamster ovary (CHO) cells. It has been reported that environmental parameters like temperature and pH and nutritional ingredients are key factors that can influence cell growth, carbon and/or nitrogen source metabolism and foreign protein expression in CHO cell suspension culture. Objective: Effects of culture process parameters (temperature and pH) on cell growth and anti-CD20 antibody expression by CHO cells were investigated based on design of experiment (DOE), and a fed-batch strategy was successfully developed to improve anti-CD20 antibody expression level with amino acid supplementation. The results show that temperature was a key factor for anti-CD20 antibody expression: 35℃was the optimal temperature with an increased cell density and target mAb yield. However, the impact of pH on mAb production by CHO cells was not significant and there were no interaction between pH and temperature. The optimal culture conditions were 35℃ and pH7.0 according to the analysis of DOE predictive profiler. In addition, it found that residual concentrations of tyrosine and cysteine in culture was below 0.1mmol/L at late stage of cultivation process under the optimal culture condition. As such, additional 1.5mmol/L tyrosine and 1mmol/L cysteine were fed on day 2, led to an increase in anti-CD20 antibody titer by 24.1% and no changes in glycosylation of anti-CD20 antibody.