By Xiaofeng (Kevin) Han, and Ma Sha, Eppendorf, Inc., Enfield, CT, USA
Anchorage-dependent cells, such as Vero cells, are widely used as a platform for viral vaccine production. In perfusion bioprocesses it is possible to constantly add nutrients and to remove byproducts, while retaining the cells in the bioreactor. Therefore higher cell densities can be reached than in conventional batch or fed-batch processes. In this study we tested the suitability of a spin filter as cell retention device. We cultivated Vero cells on Cytodex® 3 microcarriers (10 g/L) in an Eppendorf 3 L glass vessel using a microcarrier spin filter coupled with a pitched-blade impeller. The microcarrier spin filter is a cylinder-shaped cage that spins with the impeller shaft and is covered with a large 75-micron screen designed to prevent microcarriers from being collected with the waste media during perfusion. The process was controlled with a BioFlo® 320 bioprocess control station and there were no additional devices needed for the perfusion. With the unique design of this spin filter, we easily cultivated anchorage-dependent Vero cells in perfusion mode on microcarriers and ensured a consistent supply of nutrients and the removal of toxic byproducts.
At a modest microcarrier loading density of 10 g/L, we achieved Vero cell density of 8.0 × 106 cells/mL in 9 days, sufficient for inoculation of a 40 L CelliGen® 510 packedbed bioreactor designed for vaccine production, assuming > 50% cell recovery. We demonstrated great potential of using microcarrier spin filter for attachment cell based vaccine production scale-up.