Effects of Both Temperature and pH Shifting on Albumin-Erythropoietin Production in Recombinant CHO Cells

초록

Effects of environmental factors on cell growth and recombinant protein production have been widely investigated in CHO cell cultures. In this work, we investigated the effects of both temperature and pH on a recombinant CHO cell line expressing human albumin-EPO. The culture temperature was changed from 37℃ to 34℃ before the stationary phase at day 3. It was found that the cell viability remained high and the maximum albumin-EPO production level increased to 1.2-fold higher than that of culture with constant temperature at 37 C. Bi-phasic cultivation based on temperature shifting was confirmed to be a suitable tool for controlling cell proliferation and albumin-EPO expression in CHO cells. The culture pH was controlled at various levels by using 0.5 N NaOH. Maximum cell density reached up to 4.2 x 106 cells/mL at day 4 by maintaining pH 7.2, which was 8% higher than that of control culture. The highest productivity was obtained at pH 6.8. Based on these results, pH shift two-stage culture was performed. In the first half stage of cultivation, pH was controlled at 7.2 and the pH shifted at day 5 to 6.8 and 7.0, respectively. However, as reported in the previous studies, the culture pH at 37℃ did not influence albumin-EPO production. Therefore, it is expected that the simultaneous use of both temperature and pH shifting can improve the performance of CHO cells regarding cell growth, recombinant protein production.