Feasibility study on the use of hyperosmolar medium for improved antibody production of hybridoma cells in a long-term, repeated-fed batch culture

Abstract

To test the feasibility of using hyperosmolar medium for improved antibody production in a long-term, repeated fed-batch culture, the influence of various culture conditions (serum concentration and cultivation method) on the hybridoma cells' response to hyperosmotic stress resulting from sodium chloride addition was first investigated in a batch culture. The degree of cell growth depression resulting from hyperosmotic stress was dependent on serum concentrations and cultivation methods (static and agitated cultures). Depression of cell growth was most significant in agitated cultures with low serum concentration. However, regardless of serum concentrations and cultivation methods used, the hyperosmotic stress significantly increased specific antibody productivity (q _MAb). Increasing osmolality from 284 to 396 mOsm kg⁻¹ enhanced the q_MAb in agitated cultures with 1% serum by approximately 124% while the similar osmotic stress enhanced the q _MAb in static cultures with 10% serum by approximately 153%. Next, to determine whether this enhanced q_MAb resulting from hyperosmotic stress can be maintained after adaptation, long-term, repeated-fed batch cultures with hyperosmolar media were carried out. The cells appeared to adapt to hyperosmotic stress. When a hyperosmolar medium (10% serum, 403 mOsmkg⁻¹) was used, the specific growth rate improved gradually for the first four batches and thereafter, remained constant at 0.040±0.003 (average ± standard deviation) hr⁻¹ which is close to the value obtained from a standard medium (10% serum, 284 mOsmkg⁻¹) in the batch culture. While the cells were adpating to hyperosmotic stress, the q_MAb was gradually decreased from 0.388×10⁻⁶ to 0.265×10⁻⁶ μg cell hr⁻¹ and thereafter, remained almost constant at 0.272±0.014× 10⁻⁶ μg cell⁻¹ hr⁻¹. However, this reduced q _MAb after adaptation is still approximately 98% higher than the q_MAb obtained from a standard medium in the batch culture.