2-DIMENSIONAL GEL-ELECTROPHORESIS FOR CONTROLLING AND COMPARING CULTURE SUPERNATANTS OF MAMMALIAN-CELL CULTURE PRODUCTIONS SYSTEMS

A recombinant Chinese hamster ovary cell line, producing human erythro poietin, was cultivated in a continuous mode in a stirred tank reactor applying different dilution rates. In order to monitor the stability of this expression system, product and non-product proteins of the cel l culture supernatant were analyzed by two-dimensional electrophoresis . The consistency of the isoforms of the recombinant product was deter mined by western blot combined with specific staining. The same cell l ine was propagated in a high cell density cultivation system based on macro-cell-aggregates. The patterns of secreted proteins of the eel li ne cultivated in the different systems were compared in order to detec t modifications in protein expression of the product and of non produc t proteins relevant for cell culture supernatant. Hardly any alteratio ns in two-dimensional pattern were detectable. The isoforms of erythro poietin, as well as the overall pattern of secreted proteins, detectab le with the two-dimensional electrophoresis method were remarkably sta ble under different cultivation conditions.