ATF for cell culture harvest clarification: mechanistic modelling and comparison with TFF

Abstract

BACKGROUND Extracellular expression of proteins in mammalian cell culture systems requires clarification in order to separate the cell mass from soluble expressed protein. This task is typically accomplished by membrane based separations. This paper explores the use of alternating tangential flow (ATF) filtration for clarification. RESULTS The superiority of ATF over the conventional tangential flow filtration (TFF) has been demonstrated with respect to the required sizing of the filter and both processes have been modeled. Modeling of TFF is based on assumptions of constant conditions of pressure, concentration of foulant, or flux. Modeling of ATF involved simultaneous variations in all three parameters and hence the traditional models that describe fouling of membranes under constant pressure filtration were appropriately modified to incorporate these variations. The resulting models are amenable to ‘exponent analysis’ and allow identification of the mechanism of ATF fouling among pore blocking, intermediate pore blocking, pore constriction, and cake formation. Complete pore blocking has been identified as the dominant mechanism for the system at hand involving clarification of mammalian cell culture harvests using ATF as well as TFF. CONCLUSIONS ATF has been implemented and successfully demonstrated to be superior to TFF for mammalian cell culture clarification. The mechanism of fouling with ATF as well as TFF has been identified successfully. The modeling approach proposed here can be applied to a variety of industrial systems to determine the mode of fouling and to mitigate it. Also, sizing predictions based on mechanistic modeling can be useful for process optimization. © 2016 Society of Chemical Industry

AAV process intensification by perfusion bioreaction and integrated clarification

“…The same was not verified for all TFDF runs, with TFDF1 filter becoming severely fouled after cell lysis as a result of the high cell concentration at the time of harvest (approx. 50 × 10 6 cells/mL compared to the 23 × 10 6 cells/mL of ATF1) and/or the high concentration of impurities (Hadpe et al, 2017;Wang et al, 2017). Reducing cell concentration at the time of transfection (TFDF2 and TFDF3) led to a decrease in cell concentration and impurities at the time of harvest, thus impacting positively on the clarification step (i.e., no filter clogging/fouling).…”

Mechanistic modeling of the loss of protein sieving due to internal and external fouling of microfilters

“…Hadpe et al provided data for pressure increase and flux decay during the ATF filtration of a CHO cell culture bioreactor with hollow fiber PES microfiltration membranes. The data were modeled with modified forms of the classic blocking models.…”

Recent Developments in Bioprocessing of Recombinant Proteins: Expression Hosts and Process Development

“…In order to enhance the perfusion process yield, the bleed rate should be low (Lin et al, 2017). In ATF filtration, a diaphragm pump provides a flow of cell broth in alternating directions with a cycle time of about 1 min, and without additional shear stress and possible fouling (Gronemeyer et al, 2014;Patil and Walther, 2016;Hadpe et al, 2017). Karst et al (2016) evaluated ATF vs. TFF and observed 50% retention in TFF as compared to 10% using ATF in the perfusion bioreactor.…”