Mechanical agitation of hybridoma suspension cultures: Metabolic effects of serum, pluronic F68, and albumin supplements

Metabolic effects of the medium supplements, fetal bovine serum (FBS), Pluronic F68, and bovine serum albumin (BSA) were compared for agitated bioreactor cultures of hybridoma cells. Agitation speeds up to 600 rpm, without entrainment of gas bubbles by sparging or vortex formation, allowed examination of cell interactions with turbulent fluid forces. For cultures in FBS-supplemented RPMI media, there was no significant effect of intense turbulent fluid shear on cell growth, metabolism, or antibody, production. Serum-free cultures (Pluronic F68 or BSA supplements) at 600 rpm demonstrated greatly increased glycolysis rates during exponential growth relative to controls. Nutrient limitations caused increased rates of decline of the viable cell concentrations and a reduction in final antibody titers by around 70%. The Pluronic F68 and BSA supplements did not lead to cell protection by modifying metabolism under conditions of intense turbulent fluid shear. Supplementing the protein-free medium with FBS reduced glycolysis rates in exponential growth phase, but this did not prevent a high rate of viable cell decline and low antibody titers. We concluded that FBS does not have a metabolic effect on cells subjected to intense turbulent fluid shear. Although the agitation conditions employed in this study were more intense than generally required for agitated bioreactor culture of hybridomas, we have demonstrated the importance of considering metabolic effects of turbulent fluid forces on cultures using nutrient-rich basal media, in addition to the considerations of gas bubble effects described by other workers. (c) 1992 John Wiley & Sons, Inc.