Biphasic culture strategy based on hyperosmotic pressure for improved humanized antibody production in Chinese hamster ovary cell culture

Abstract

Hyperosmotic pressure increased specific antibody productivity ($q_Ab$) of recombinant CHO (rCHO) cells (SH2-0.32) while it depressed cell growth. Thus, the use of hyperosmolar medium did not increase the maximum antibody concentration substantially. To overcome this drawback, the feasibility of biphasic culture strategy was investigated. In the biphasic culture, cells were first cultivated in the standard medium with physiological osmolality (294 mOsm/kg) for cell growth. When cells reached the late exponential growth phase, the spent standard medium was replaced with the fresh hyperosmolar medium (522 mOsm/kg) for antibody production. The $q_Ab$ in growth phase with the standard medium was $2.1μg/10^{6}$ cells/day while the $q_Ab$ in antibody production phase with the hyperosmolar medium (522 mOsm/kg) was $11.1μg/$10^{6}$ cells/day. Northern blot analysis showed a positive relationship between the relative contents of intracellular immunoglobulin mRNA and $q_Ab$. Due to the enhanced $q_Ab$ and the increased cell concentration in biphasic culture, the maximum antibody concentration obtained in biphasic culture with 522 mOsm/kg medium exchange was 161% higher than that obtained in batch culture with the standard medium. Taken together, the simple biphasic culture strategy based on hyperosmotic culture is effective in improving antibody production of rCHO cells.