IMPROVEMENT OF THE CULTURE STABILITY OF NON-ANCHORAGE-DEPENDENT ANIMAL-CELLS GROWN IN SERUM-FREE MEDIA THROUGH IMMOBILIZATION

A murine hybridoma cell line producing a monoclonal antibody against p enicillin-G-amidase and a murine trans-fectoma cell line secreting a m onovalent chimeric human/mouse Fab-antibody fragment were cultivated i n three different media (serum-containing, low protein serum-free, and iron-rich protein-free) in flask cultures, stirred reactors and a fix ed bed reactor. In static batch cultures in flasks both cell lines sho wed similar good growth in all three media. In suspension in a stirred reactor, the hybridoma cell line could be cultivated satisfactory onl y in serum-containing medium. In low protein serum-free medium, Pluron ic F68 had to be added to protect the hybridoma cells against shear st ress. But even with this supplement only batch, not chemostat mode was possible. In iron-rich protein-free medium the hybridoma cells grew a lso in continuous chemostat mode, but the stability of the culture was low. The transfectoma cell line did not grow in stirred reactors in a ny of the three media. Good results with both cell lines were obtained in fixed bed experiments, where the cells were immobilized in macropo rous Siran(R)-carriers. The media, which were optimized in flask cultu res, could be used without any further adaptation in the fixed bed rea ctor. Immobilization improved the stability and reliability of culture s of non-adherent animal cells in serum-free media tremendously compar ed to suspension cultures in stirred reactors. The volume-specific glu cose uptake rate, an indicator of the activity of the immobilized cell s, was similar in all three media. Deviations in the metabolism of imm obilized and suspended cells seem to be mainly due to low oxygen conce ntrations within the macroporous carriers, where the cells are supplie d with oxygen only by diffusion.