Enhanced interferon-beta production by CHO cells through elevated osmolality and reduced culture temperature

For efficient production of native interferon-beta (IFN-beta) in recombinant CHO cell culture, the IFN-beta molecular aggregation that occurs during culture needs to be minimized. To do so, we investigated the effect of hyperosmolality and hypothermia on IFN-beta production and molecular aggregation in rCHO cell culture. Both hyperosmolality (470 mOsm/kg) and hypothermia (32 degrees C) increased specific native INF-beta productivity q(IFN-beta). Furthermore, they decreased the IFN-beta molecular aggregation, although severe IFN-beta molecular aggregation could not be avoided in the later phase of culture. To overcome growth suppression at hyperosmolality and hypothermia, cells were cultivated in a biphasic mode. Cells were first cultivated at 310 mOsm/kg and 37 degrees C for 2 days to rapidly obtain a reasonably high cell concentration. The temperature and osmolality were then shifted to 32 degrees C and 470 mOsm/kg, respectively, to achieve high q(IFN-beta) and reduced IFN-beta molecular aggregation. Due to the enhanced q(IFN-beta) and delayed molecular aggregation, the highest native IFN-beta concentration achieved on day 6 was 18.03 +/- 0.61 mg/L, which was 5.30-fold higher than that in a control batch culture (310 mOsm/kg and 37 degrees C). Taken together, a combination of hyperosmolality and hypothermia in a biphasic culture is a useful strategy for improved native IFN-beta production from rCHO cells.