The preparation of cryo stocks is indispensable not only for reproducible screening results, but especially for long-term production campaigns and for fulfilling regulatory expectations. Typical examples are master and working cell banks. These cultures enable a constant and reproducible quality and yield in the production process, as fresh cells can be used after specified intervals and aged cultures can be discarded.
The preparation of cryo stocks is standard for bacteria and animal cell cultures but remains a challenge for plant systems in many cases. Although cryo stocks can be prepared for plant cell cultures in principle, there is currently no established and widespread method available, as protocols have so far only been tailored to individual cell lines. Also, the conditions for pretreatment and freezing/regeneration are often device-specific and therefore difficult to transfer, scale and qualify.
So far, several cryo preservation protocols have been successfully established at Fraunhofer IME for different plant cell lines. In the Bioprocess Engineering department, we are currently merging and retesting these protocols with the aim to identify relevant factors. In the end this will facilitate a rapid transfer to other plant cell cultures and result in a structured and continuous optimization of performance.