Effect of Simultaneous Application of Stressful Culture Conditions on Specific Productivity and Heterogeneity of Erythropoietin in Chinese Hamster Ovary Cells

A single stressful culture condition induced by hypoosmotic stress (210 mOsm kg^-1), low culture temperature (32 °C), or NaBu addition (1 mM) resulted in a 1.8- to 2.2-fold enhancement of specific erythropoietin (EPO) productivity (qEPO) of recombinant Chinese hamster ovary (rCHO) cells compared to normal culture condition (37 °C and 310 mOsm kg^-1). Simultaneous application of these stressful conditions further enhanced qEPO up to approximately 5-fold. However, the quality of EPO was affected by stressful culture conditions. The proportion of acidic isoforms of EPO under a single stressful condition was 2.8-13.8% lower than that under normal culture condition. Simultaneous application of the stressful conditions further decreased the portion of acidic isoforms but not significantly. Despite 5-fold enhancement of qEPO, the portion of acidic isoforms under the simultaneous application of stressful culture conditions was 12.9-21.6% lower than that under normal culture condition. Taken together, these results suggest the potential of simultaneous application of different stressful culture conditions to the production phase of two-stage culture, where cell growth and production phases are separated, for improved EPO production.