Scaling‐up of an Insect Cell‐based Virus Production Process in a Novel Single‐use Bioreactor with Flexible Agitation

Abstract

A novel single‐use bioreactor was recently introduced to the market that is agitated by impellers suspended on flexible ropes rather than a rigid shaft. Computational fluid dynamics (CFD) models were created and validated by particle image velocimetry (PIV) to predict the bioreactor's fluid flow and mixing. The data were then used to scale‐up a Spodoptera frugiperda, subclone 9 (Sf9) insect cell‐based production of recombinant adeno‐associated virus (AAV) from a benchtop glass bioreactor to the single‐use system with 30 L working volume. This viral vector is one of the most commonly used in gene therapies. The volumetric power input was kept constant while maintaining reasonable mixing times and shear stresses between the scales. Peak cell densities of up to 7.2 × 106 cells mL−1 and maximum virus titers of 1.7 × 1011 vg mL−1 were achieved. Similar cell growth and metabolite profiles further proved the successful process transfer between the two geometrically non‐similar bioreactor systems. The pilot bioreactor yielded between 3.3 and 4.8 × 1015 vg that, depending on the therapy, can be sufficient for the treatment of a single patient.

Improvement of HEK293 Cell Growth by Adapting Hydrodynamic Stress and Predicting Cell Aggregate Size Distribution

“…The turbulence model used here is the k - shear stress transport (SST) model of Menter [ 45 ] ( corresponds to the turbulent specific dissipation rate), as it can also be directly used as a model for low Reynolds numbers (a detailed derivation can be found in Appendix B ). The rotation of the stirrer was handled by the multiple reference frame (MRF) approach as it is a steady-state analysis [ 46 , 47 , 48 ]. The relatively low speeds and axial pumping (less vortex formation compared with radial pumping stirrers) allow for the assumption of a non-free surface.…”

“…Therefore, a symmetry plane was used as boundary conditions for the liquid surface, as is usual for single-phase stirred bioreactor simulations [ 48 , 49 , 50 ]. A no-slip wall boundary condition was used for the bioreactor wall, stirrer, and internals [ 46 , 47 ]. The OpenFOAM solver simpleFOAM was employed, which uses the Semi-Implicit Method for Pressure-Linked Equations (SIMPLE) algorithm for the pressure-velocity coupling [ 51 ].…”

Integration Approaches to Model Bioreactor Hydrodynamics and Cellular Kinetics for Advancing Bioprocess Optimisation

“…There have been valuable contributions made in the literature for the application of CFD to model volumetric mass transfer coefficient (k L a) [ 40 , 41 , 42 ], power density (P/V) [ 43 , 44 , 45 ], mixing time [ 46 , 47 , 48 ], Kolmogorov length ( λ k ) [ 49 , 50 ], shear stress (τ) [ 51 , 52 , 53 ] and sedimentation [ 54 , 55 ] in bioreactors. Cell culture dynamics, metabolism and product glycosylation have been modelled in the past using mechanistic models [ 56 , 57 , 58 ], statistical models [ 59 , 60 , 61 ], and hybrid models [ 61 , 62 ].…”