Characterization and comparison of ATF and TFF in stirred bioreactors for continuous mammalian cell culture processes

In this work, two external filtration devices for cell retention, the commercial alternating tangential flow (ATF) system and a tangential flow filtration (TFF) setup driven by a bearingless centrifugal pump were compared. Physical characterization of the bioreactor hydrodynamics revealed significantly smaller maximum stress values in the ATF at similar mixing and oxygen mass transfer rates. Suitable operating parameters in terms of aeration, stirring and operation of the retention device were determined. Steady culture of Chinese hamster ovary (CHO) cells at 20, 40 and 60 × 106 cells/mL for at least one week was achieved in perfusion at a fixed harvest rate of one reactor volume per day for both setups. Contrary to the ATF, considerable retention (up to 50%) of the produced monoclonal antibody in the TFF was observed, however without significant difference in product quality. The integration of physical and cell culture characterization allows the comprehensive assessment of cell culture performance. The presented approach can serve as a general procedure to develop a scalable mammalian cell perfusion culture.