Stirring rate regulates the proliferation and metabolism of microencapsulated recombinant CHO cells

Stirred tank bioreactors are the most widely used method for the large-scale culture of mammalian cells. However, the scale of stirred tank bioreactors is limited by insufficient oxygen/nutrient mixing and the accumulation of waste products in high cell density cultures. The most effective method to solve these problems is to increase the stirring rate; this usually leads to increased cell proliferation, but can decrease the utilization of nutrients for recombinant protein synthesis. To investigate the effects of stirring rate on the proliferation, metabolism, and recombinant protein yield of microencapsulated recombinant Chinese hamster ovary (rCHO) cells, the cells were cultured under different stirring rates, and cell viability, metabolic activity, and protein yield were measured. Microencapsulation promoted Desmodus rotundus salivary plasminogen activator expression, and higher stirring rates promoted increases in microencapsulated cell density and metabolic activity. However, the maximum yield of recombinant protein was obtained at a moderate stirring rate, whereas protein yield was decreased at the highest tested stirring rate. The stirring rate had a significant impact on the growth and protein expression of microencapsulated rCHO cells, and a specific stirring rate was identified to maximize the yield of recombinant protein.