Intensified perfusion culture (IPC) reduced recombinant protein fragmentation

Mammalian cells remain the mainstay of biological production host. In industry, cultivating and harvest strategies are sorted in batch mode (e.g., batch, fed-batch, concentrated fed-batch and intensified fed-batch) and continuous mode (e.g., perfusion). To retrieve greater productivity and better product quality, especially for the sensitive products prone to fragmentation, culture modes with various modifications are innovated (e.g., intensified perfusion culture [IPC]). In our study, we demonstrated that the fragmentation of Fc-fusion product (Molecule A) is time-dependent in traditional fed-batch (TFB) culture. The fragmentation proportion increased from 3.8% to 12.4% for Clone A, 0.8% to 1.7% for Clone B and 0.9% to 2.0% for Clone C from Day 10 to Day 14. By applying a novel bioprocess, IPC, which allows continuous feeding of the fresh medium and constant removal of the spent medium without bleeding cells to maintain a defined constant viable cell density, the fragmentation was reduced to 0.3% while the productivity was increased from 2.96 g/L to 15.51 g/L for Clone A. To validate whether the fragmentation reduction is product-sensitive, plasmids carrying the DNA sequences of two other Fc-fusion molecules (Molecule B and Molecule C) were transfected into the host. The results showed consistent fragmentation reducing effect by using IPC. Furthermore, the cultivation scale was expanded to 50 L and 1000 L. A minimum fragmentation level below 0.1% was observed for Molecule C. Our study revealed the capability of IPC in reducing Fc-fusion protein fragmentation and the reproducibility when scaling up while maintaining high productivity.