Dialysis-fixed-bed Cultures for Highly Efficient Production of Chimeric Fab-fragments with Transfec Toma Cells in Protein-free Medium

Abstract

The extremely shear sensitivetransfectoma cell line FAB#10, producing a chimeric Fab-antibody fragment specific for the human carcinoembryonic antigen (CEA), was cultivated in fixed bed reactors, were the cells were immobilized in macroporous carriers. As the cell line had a very low productivity, the fixed bed reactors were coupled with dialysis membranes, were low molecular weight metabolites are removed through the membrane and high molecular products are enriched. In fixed bed systems the cell line was stable during long term cultures. With the dialysis technique Fab-concentrations up to 8,000 μg l⁻¹ could be obtained, appr. 16 times higher compared to fixed bed cultures without dialysis or batch cultures with suspended cells.

If nutrients are supplied through the membrane, a high loss of nutrients has to be considered. In a novel “nutrient-split” feeding strategy concentrated medium is fed directly to the fixed bed unit, whereas a buffer solution is used as dialysisfluid. This feeding strategy reduces the required medium per mg of product significantly.