ATF-based perfusion processes from 250 mL to 50 L scale

Single-use technologies have become indispensable in the field of biopharmaceutical production. Due to the high production costs of such biopharmaceuticals, ongoing improvement and optimization of production processes is necessary. Process intensification, which is currently a strong trend in this context, deals with this topic in detail. In the area of upstream processing, the trend is towards perfusion processes. The centerpiece of every perfusion is the cell retention system. While tangential flow filtration (TFF) and alternating TFF (ATF) are usually used on a production scale, sedimentation-based semi-perfusion processes are frequently used as mL-scale down models. However, direct scaling to larger bioreactors is critical here, so further experiments must be carried out at benchtop scale. In order to be able to work in perfusion mode on a 250 mL scale without the high throughput version of the Ambr 250 (Sartorius), the modular version of the Ambr 250 was used in combination with the smallest available single-use ATF device from Repligen for the development of perfusion processes. With this setup, not only cell densities of >150 x 10^6 cells mL−1 in N−1 perfusion mode were achieved with the ExpiCHO-S cell line used, but also a continuous cultivation process was carried out as a proof of concept. Both the viable cell volume and the volumetric productivity were similar to a 2 L reference reactor. The scalability of the ATF perfusion processes from 2 L scale to pilot scale was additionally demonstrated in 50-day perfusion cultivations in Thermo Scientific's HyPerforma DynaDrive. With the CHO K1 cells used here, more than 1 g L−1 d−1 IgG could be harvested. The perfusion processes developed in this work provide the basis for the direct scaling up of ATF-based perfusion processes developed at the mL scale to the pilot scale.