Recombinant viruses (e.g. lentivirus and adeno-associated-virus) can be used as human gene therapy vectors. They are mainly produced in adherent cell cultures (e.g. HEK293T, A549, VERO) in Roller Bottles or multiple-tray-stacks using either transient transfection or infection strategies. Therefore, the Integrity® iCELLis® (ATMI LifeSciences) line of bioreactors offers a new production alternative with stronger process controls and ease of scale-up.
The iCELLis bioreactor is designed for adherent cell culture applications. Cells grow on microfibers carriers packed in a fixed-bed providing up to 500m² of growth surface area in a small reactor volume. Environmental conditions, combined with the large growth surface area in the iCELLis yields high cell productivity.
First, a mirrored approach of the previous production in multiple-tray stacks was set-up in the small scale iCELLis bioreactor. Transfection/infection efficiency through the fixed-bed of the iCELLis system is evaluated by Flow Cytometry. At harvest, extracellular viral vectors are cultivated in the cell culture medium. In the case of intracellular vectors, cell disruption is carried out directly in the bioreactor by physico-chemical methods.
The results achieved indicated titer for AAV of 5.108 vg/cm² in the small scale iCELLis (versus 3.108 vg/cm² in 5-layer stack) and 0.5-1 log titer for paramyxovirus (versus tissue culture flask). Results of transient transfection processes with iCELLis showed results similar to the 5-layer stack process.