A Chinese hamster ovary (CHO) cell line that expresses human erythropoietin (huEPO) was in a 2-L Cytopilot fluidized-bed bioreactor with 400 mL macroporous Cytoline-1 microcarriers and a variable perfusion rate of serum-free and protein-free medium for 48 days. The cell density increased to a maximum of 23 x 10(6) cells/mL, beads on day 27. The EPO concentration increased to 600 U/mL during the early part of the culture period (on day 24) and increased further to 980 U/mL following the addition of a higher concentration of glucose and the addition of sodium butyrate. The EPO concentration was significantly higher (at least 2x than that in a controlled stirred-tank bioreactor, in a spinner flask, or in a stationary T-flask culture. The EPO accumulated to a total production of 28,000 kUnits over the whole culture period. The molecular characteristics of EPO with respect to size and pattern of glycosylation did not change with scale up. The pattern of utilization and production of 18 amino acids was similar in the Cytopilot culture to that in a stationary batch culture in a T-flask. The concentration of ammonia was maintained at a low level (< 2 mM) over the entire culture period. The specific rate of consumption of glucose, as well as the specific rates of production of lactate and ammonia, were constant throughout the culture period indicating a consistent metabolic behavior of the cells in the bioreactor. These results indicate the potential of the Cytopilot bioreactor culture system for the continuous production of a recombinant protein over several weeks.

A stable CHO cell line that expresses human erythropoietin (huEPO) was grown in a Cytopilot fluidized-bed bioreactor for 48 days with a variable perfusion rate. The cells were entrapped in porous microcarriers (400 ml) within the main column of the bioreactor (2 litre). EPO accumulated to a total production of 28,000 kUnits over the culture period. The specific EPO production increased during the later part of the culture probably in response to a higher glucose concentration and an addition of sodium butyrate. The cell density increased to per ml beads. The culture profile in the fluidized-bed bioreactor was compared with three modes of batch culture. The high volumetric yield of EPO attained in the Cytopilot bioreactor indicates its potential as a system for large-scale production.