BIOLOGICAL RESPONSES OF HYBRIDOMA CELLS TO HYDRODYNAMIC SHEAR IN AN AGITATED BIOREACTOR

Effects of long-term hydrodynamic shear on hybridoma cells were investigated in a 250-ml continuous stirred-tank reactor (CSTR). Cells grown at steady state were subjected to step changes in agitation rates. Cell viability, glucose consumption, and monoclonal antibody (MAb) production were determined at high agitation rates and compared with the control (100 rev min-1). Impeller tip speeds higher than 40 cm s-1 caused a significant drop in cell concentration and respiration activity, and increased lactate dehydrogenase (LDH) release to the culture medium. Also, high agitation speeds caused a decrease in MAb concentration and an increase in specific glucose consumption rate. The effects of dilution rate and serum concentration on the sensitivity of hybridoma cells to hydrodynamic shear were determined. Serum was found to protect the cells against shear damage and had a significant positive effect on hybridoma growth and MAb production. Shear damage on cells in CSTR was approximated to first-order kinetics. The death rate constant increased sharply at impeller tip speeds above 40 cm s-1.