Optimization of Chinese hamster ovary cell expression-based Fc fusion protein preparation process

Objective To optimize Chinese hamster ovary (CHO) cell expression-based Fc fusion protein preparation process. Methods For the upstream cell culture process, the medium proportion and feeding strategy were optimized first in the shake flask, and then the optimized process was scaled up to the bioreactor and its feasibility was confirmed. For the the downstream protein purification process, the elution condition of protein A affinity chromatography and the balance condition of anion exchange chromatography were optimized. Results For the upstream cell culture process, the seed culture medium, basic medium (CD OptiCHO) and basic medium (CDM4Mab) were mixed at 2∶1∶1 ratio. Cell density and viability of fed-batch culture by feeding at 3, 6 and 9 d were good, and this feeding design cost was low. For the downstream protein purification process, when pH3.3 eluant was used for protein A affinity chromatography, the recovery and purity of Fc fusion protein were 94.7% and 98.64%, respectively; when pH5.0-pH5.5 balance liquid was used for anion exchange chromatography, the recovery and purity of Fc fusion protein were more than 98% and 99%, respectively. Conclusion CHO cell expression-based Fc fusion protein preparation process is optimized successfully, and provides ideas for optimization of the therapeutic antibody preparation processes. Key words: Recombinant fusion proteins; Culture media; Chromatography, ion exchange; Chromatography, affinity; Process optimization