(369f) Calculation of Pressure Profile of TFF for Clarification of HEK Cell Culture with Cell Lysate Using Hollow Fiber MF with Asymmetric or Symmetrical Structure

AAV is the most promising vector for gene therapy, but its purification process is not straightforward, particularly the stable clarification and harvest of AAV from cell culture containing lysate with very low viability is challenging. To this issue, previously, studies of harvesting AAV by tangential flow filtration (TFF) showing the effectiveness of reverse asymmetric hollow fiber membranes have been reported and the critical flux at different shear rates has been experimentally demonstrated.

In this report, quantitative reproduction of experimental critical flux of tangential flow filtration, which is important for stable harvesting, using an analytical equation based on the mass balance, are presented. Furthermore, using this analytical equation, the TFF filtration behavior of HEK cell culture with cell lysate using three types of hollow fiber MF with different structures are reproduced. The three types of hollow fiber MF (BioOptimal MF-SL, UMP, and UJP) have different average pore sizes (0.4 μm, 0.2 μm, and 0.65 μm), and while MF-SL has a distinct asymmetric structure, UMP and UJP have a symmetrical structure. Therefore, when HEK cell culture containing lysate with viability of almost 0% is TFF filtered under the constant permeate flux condition, the filtration pressure behavior exhibits completely different profiles depending on the membrane. The calculation results obtained using analytical equations based on mass balance can reproduce these pressure profiles by optimizing the filtration parameters included in the equations. Furthermore, by modeling the structural characteristics of each of the three types of membranes using a multilayer membrane structure and performing numerical calculations of filtration behavior, it was quantitatively reproduced that different pressure profiles were obtained for each modeled membrane structure.