Process Control and On-Line Feeding Strategies for Fed-Batch and Dialysis Cultures of Hybridoma Cells

Abstract

The concept of the fed-batchstrategy was to minimise the formation of inhibiting metabolites and to increase the yield of monoclonal antibodies by carefully supplying substrates. A process control system based on fieldbustechnology was used for monitoring and control. Externalprogram routines were implemented to control dissolved oxygen (DO) and to calculate the oxygen uptake rate (OUR) and cumulative oxygen consumption (COC) simultaneously. Concentrated feed solution was supplied according to the off-line estimated stoichiometric relation between oxygen and glucose consumption (GC). The developed feeding strategy initiated feeding automatically when the OUR decreased because of substrate limitation. Hybridoma cells were cultivated in batch and fed-batch cultures in laboratory scale using media containing an iron-rich, protein-free supplement. The antibody concentration increased three- to four-fold compared to the conventional batch culture when applying this strategy. It was not possible to avoid inhibition by metabolic products such as lactate and ammonium during fed-batch phase. This was accomplished by using dialysis and?nutrient-split? feeding in a membrane dialysis reactor [Portner et al., 1997] and resulted in a ten-fold increase of the antibody concentration compared to the batch.