Modulating and optimizing Pluronic F‐68 concentrations and feeding for intensified perfusion Chinese hamster ovary cell cultures

Abstract Perfusion culture is often performed with micro‐sparger to fulfill the high oxygen demand from the densified cells. Protective additive Pluronic F‐68 (PF‐68) is widely used to mitigate the adverse effect in cell viability from micro‐sparging. In this study, different PF‐68 retention ratio in alternating tangential filtration (ATF) columns was found to be crucial for cell performance of different perfusion culture modes. The PF‐68 in the perfusion medium was found retained inside the bioreactor when exchanged through ATF hollow fibers with a small pore size (50 kD). The accumulated PF‐68 could provide sufficient protection for cells under micro‐sparging. On the other hand, with large‐pore‐size (0.2 μm) hollow fibers, PF‐68 could pass through the ATF filtration membranes with little retention, and consequently led to compromised cell growth. To overcome the defect, a PF‐68 feeding strategy was designed and successfully verified on promoting cell growth with different Chinese hamster ovary (CHO) cell lines. With PF‐68 feeding, enhancements were observed in both viable cell densities (20%–30%) and productivity (~30%). A threshold PF‐68 concentration of 5 g/L for high‐density cell culture (up to 100 × 10 6 cells/mL) was also proposed and verified. The additional PF‐68 feeding was not observed to affect product qualities. By designing the PF‐68 concentration of perfusion medium to or higher than the threshold level, a similar cell growth enhancement was also achieved. This study systematically investigated the protecting role of PF‐68 in intensified CHO cell cultures, shedding a light on the optimization of perfusion cultures through the control of protective additives.