Development of an on-line control system for the cultivation of animal cells in a hollow-fiber reactor using flowing injection analysis and a visual programming language.

A system for the independent control of ammonia and glutamine in a hollow-fiber reactor has been developed. On-line analysis of the two chemical species was performed using FIA. A custom-made program has been written to fully automate the FIA, to perform measurements, calibrations and data acquisition, and to activate two peristaltic feed pumps. Diagnostic tests were also automatically performed in order to identify, and in some cases eliminate, erroneous measurements and calibrations due to instrument failures. For this purpose, a visual programming language (LabVIEW) has been chosen. Ammonia concentration was controlled by varying the medium supply rate to the hollow-fiber reactor which was shown to behave like an ideal-stirred tank reactor. The glutamine concentration was controlled through the intermittent activation of a pump delivering a concentrated solution of this species to the reactor. This control system was tested with a culture of hybridoma cells at three different ammonia and one glutamine set-points. The hollow-fiber reactor was successfully operated automatically for more than 1200 h with ammonia and glutamine concentrations accurately controlled at non-limiting levels. The visual programming environment was found to be reliable and highly suitable for the development of custom programs for bioprocess control.

Systematic improvement of a chemically-defined protein-free medium for hybridoma growth and monoclonal antibody production.

A chemically-defined protein-free medium (FMX-Turbodoma) has been improved for the production of monoclonal IgA antibodies by hybridoma cells, using a systematic method. Cell growth rate, IgA production, activity and molecular weight pattern have been used as optimization criteria. Of potentially important supplements, glucose, glutamine, Pluronic acid F-68 as well as several amino acids had significant beneficial effects. A determination of amino acids profiles via HPLC analysis allowed the formulation of a balanced medium. Unbalanced supplementations of amino acids were found undesirable because of the toxicity of some amino acids at high concentration. Compared with the basal medium, the maximum viable cell and final IgA concentrations in the final version of the protein-free medium were increased by 130% and 700%, respectively, whereas the IgA molecular weight pattern and in vitro activity were not affected. The IgA production was even higher than in a serum-containing medium (RPMI 1640 + 10% FCS) and the price of the protein-free medium is about 20% of this serum-containing medium. This makes such a protein-free medium very convenient for laboratory and large-scale production.