Modeling and Application of Controlled-fed Perfusion Culture of CHO Cells in a Bioreactor

The controlled-fed perfusion culture, integrating the advantages of both the fed-batch and perfusion cultures, was applied in the culture of recombinant CHO cells expressing HBsAg. To control and optimize the process, a model was established to closely combine the feeding and perfusion operation on a basis of step-by-step strategy. The culture process was divided into many consecutive sections in the time dimension, and the feeding and perfusion rates in each section were calculated with the data in the former sections. The feeding operation was controlled by a feeding model to supplement with exact nutrients, while the perfusion operation was controlled by a perfusion model to keep byproduct concentration at low level. Linking by glucose, lactate and ammonia concentrations, the two separate models were integrated to globally control the cell culture process. By using this control strategy, the toxic byproducts were kept below their inhibitory concentrations, and a viable cell density of 13 · 109 cells L–1 and the HBsAg production of 1.65 mg L–1 were achieved in controlled-fed perfusion mode, representing an almost two-fold increase over a perfusion culture