High density fed-batch cultures for hybridoma cells performed with the aid of a kinetic model

Abstract

Hybridoma fed-batch cultures with either standard medium as feed or concentrated medium as feed and removal of toxic metabolites through dialysis were performed by using model calculations for “a priori” determination of process parameters. In a first step a kinetic model for specific growth and death rate, respectively as well as for substrate uptake and metabolite production rates was formulated. In a bed-batch culture with standard medium as feed the appropriate time for start of the feeding pump and the increase of feed rate were determined “a priori”. The glutamine concentration was controlled at 0.04 mmoll−1. “A priori” calculation and course of the culture coincided rather well. A cell concentration of 3.2×106 cells ml−1, a MAb-concentration of 54 mg MAb l−1 and a MAb-time-space-yield of 0.53 mg MAb l−1h−1 were obtained. For further increase of the efficiency a high density fed-batch process was developed, where concentrated medium is fed to the cells and the accumulating toxic low molecular weight metabolites are removed through a dialysis membrane into a dialyizng fluid. In a membrane dialysis reactor consisting of a culture chamber and a dialyzing chamber, which are separated by a cylindrical dialysis membrane, again model calculations were used to determine feed rate and exchange rate of dialyzing fluid. A viable cell density of 1.2×107 cells ml−1 and a MAb concentration of 425 mg l−1 were reached in a culture with stepwise feeding of 10 x concentrated medium and exchange of dialyzing fluid for removal of low molecular metabolites. The course of the culture could be predicted “a priori” rather well. The MAb-time-space-yield was 2.47 mg MAb l−1h−1, appr. 5 times higher compared to fed-batch cultures with standard medium as feed.