Plant cell cultures are an emerging alternative production system for recombinant pharmaceuticals, combining a higher eukaryotic expression system with fully contained bioreactor cultivation in extremely high scales on simple, defined media and without many of the issues implied by viral safety. Recently, the first recombinant biopharmaceutical produced in plants has completed Phase III trials and has been made available to selected patients.
At the Department of Integrated Production Platforms, we have a 20-year track record of plant cell culture cultivation in stirred-tank reactors up to the 100 L scale and using sophisticated fermentation strategies such as fed-batch and continuous fermentation (see picture). Continuous fermentation of plant cell cultures needs some careful adaption of the fermentation hardware, e.g. with respect to pump rates and piping diameters to accommodate the special properties of plant cells. At the Fraunhofer IME, cultures have been run in a pseudo-steady state for up to 1200 hours, thus generating higher volumetric productivity at reduced bioreactor sizes.