Development of bioreactor operation strategy for recombinant antibody production by rCHO cells

Abstract

The stirred tank bioreactor is the most important type for industrial recombinant protein production processes. The impact of environmental parameters on process performance is one of the most crucial issues when cultivating mammalian cells in a bioreactor. In a systematic approach agitation speed, dissolved oxygen, pH and temperature of rCHO cell cultures in controlled bioreactors were varied and investigated the impact on cell growth, antibody production and cell metabolism. It was found that the low pH and temperature exerted the most significant effects on cell line performance by mainly reducing cell growth and metabolism leading to an increased viable cell integral. Perfusion culture of recombinant Chinese hamster ovary cells, producing recombinant antibody against the S surface antigen of Hepatitis B virus, were carried out in continuous and intermittent mode using a Centritech Lab II Centrifuge. In the continuous perfusion process, despite the absence of shear stress from the pump head, long-term operation was not possible because of continuously repeated exposure to nutrient limitation, oxygen limitation, and low temperature, as well as shear stress from centrifugal force. In the intermittent perfusion processes, the frequency of cell-passage through the centrifuge was substantially reduced, compared with the continuous perfusion mode; however, the degree of reduction could not guarantee stable long-term operation. Although various operating parameters were applied in the intermittent perfusion cultures, high cell densities could not be maintained stably. In a single bioreactor culture system, a specific cell that is returned from the centrifuge to the bioreactor could be transferred from the bioreactor to the centrifuge again in the next cycle. This repetitive damage, caused by shear stress from the pump head and centrifugal force, as well as exposure to suboptimal conditions such as nutrient limitation, oxygen limitation, and low temperature below...