Complete clarification solution for processing high density cell culture harvests

• Flocculation approach simplifies the clarification of high cell density cultures.
• Depth filter area is reduced for a more economical clarification process.
• High host cell DNA clearance is observed upon treatment with polycationic polymer.
• The pDADMAC detection assay utilizing SPR spectroscopy is presented.

Traditional clarification of mammalian cell culture typically combines multiple separation technologies to remove cells in a primary step, and colloids in a secondary step. Recent advances in mammalian expression systems have not only led to cell cultures with very high density and increased protein titers, but also to feed streams with a high proportion of solids and colloids that reduce the efficiency of the separation step. Issues with scale-up, flexibility and installation limit the attractiveness of centrifugation, whereas clarification solely by depth filtration can be costly due to high filter areas required. Therefore, an efficient manufacture process must be developed to overcome these restrictions. In this study we present a complete separation solution that combines cell harvest pretreatment with a polycationic flocculating agent (polydiallyldimethylammonium chloride or pDADMAC), followed by depth filtration using depth filters that were specifically developed for filtration of flocculated or precipitated feed streams. Multiple antibody feed streams treated with pDADMAC and subsequently filtered using pretreatment adapted depth filters resulted in improved removal of cells and colloids, increased clarification throughput, efficient reduction of DNA and high process yield. The residual level of pDADMAC in the filtrates was assessed by surface plasmon resonance spectroscopy. Overall, this next generation clarification solution presented herein led to a robust, high yield, economical separation process with enhanced impurity removal that can be readily incorporated into current clarification platforms.