Process Development And Optimization For DHFR-CHO Cells Based On Lipid Metabolism

The monoclonal antibody drugs with large-scale animal cell culture have become the mainstream of biopharmaceuticals and have strong market competitiveness. However, development of antibody drugs takes long time and high cost that can not meet the demands of the market. Therefore, it is essential to establish efficient cell culture process to mainly reduce the cost of antibody drugs.This paper focused on two processes with high and low antibody titer (HP vs. LP) to found that lipid metabolism was significantly different. Dry lipid weight and dry cell weight increased with antibody production, while dry lipid weight increased much faster in HP process than that of LP. Dry lipid weight of HP reached to 83.70 ± 0.04×10-9 mg/cell, which was 2.35 times than that of LP. Integral of viable cell concentration (IVCC) of HP was 1.52-fold higher and the final antibody yield was 3 times than that of LP. Cellular phospholipids had significant difference, indicating that phospholipids plays an important role in cell growth and antibody expression. Then four precursors (A, B, C and D) of three important phospholipid (PC, PE, PS) were analyzed by 2-Level Factorial Design experiment to reveal that Component A had significant effect on cell growth and antibody production.Secondly, the effects of component A on cell growth and antibody production were confirmed in 2 L bioreactor, which showed improved cell viability and antibody production. The maximum cell density was 1.09 times, the antibody production was 2.39 times in the positive control cell culture than negative control cell culture.Finally, the optimal concentration of component A was determined by dose titration in basal and feed medium to achieve improved cell growth and mAb titer. The results indicated that low cell viability and antibody production were achieved with no component A addition. Antibody production increased with the concentration of component A, while IVCC had little changes. The optimal concentration of A was 95.33 mg/L in basal medium, and 189 mg/L in feed medium. It was verified that in 2 L bioreactor, the optimal concentration of component A increased the final IVCC to 79.16×109 cells-day/L, and mAb production rate reached 34.07 mg/(109cells-day),74.29% and 18.71% higher than that of control, respectively; consequently, mAb titer reached 2.04 g/L,1.83-fold higher than that of control.In this paper, lipids were found to have a significant effect on CHO cell growth and antibody expression. Moreover, the optimal concentration of component A in basal and feed medium was determined. Based on the lipid metabolism, an economical and efficient cell culture process could be established. On the other hand, this work provides the basis for serum-free medium development and for large-scale production of monoclonal antibody in the future.