Innovative Approaches to N-1 Perfusion Bioprocesses: Media Concentrates, Media Optimization and PAT Integration

Abstract

The increasing demand for biopharmaceuticals makes the intensification of their production an important task. In this work three approaches were investigated in the scope of N-1 perfusion of Chinese hamster ovary (CHO) cells: the use of concentrated perfusion media, the optimization of media composition and the application of Raman spectroscopy as aprocess analytical technology (PAT). Prestage perfusion medium was concentrated up to threefold and stored for five weekscold in the dark and at room temperature with and without light exposure. Light, rather than temperature, was the dominant factor in the degradation of growth-relevant components. Cold and light-protected concentrates showed no loss in growth performance anddynamic light scattering confirmed no formation of precipitation up to threefold concentration. Concentrating the medium up to threefold is therefore recommended to reduce themedia footprint, provided it is stored cold and light-protected. A perfusion operation with separate feed lines for concentrate and water for injection was programmed and tested ina 1.1 L bioreactor. Four medium compositions, including dilution with phosphate buffered saline (PBS), werescreened in 20 mL spin tube semi-perfusion for two CHO cell lines. The most relevantfindings were tested further in a 1.1 L bioreactor with tangential flow filtration and parallel satellites in spin tubes. Dilution with PBS, beneficial for another cell line in earlier work, did not yield a real improvement for the cell lines studied here. Finally, a PLS model based on 421 Raman spectra predicted the antibody titer in thepermeate with good accuracy (R2 = 0.96), demonstrating the feasibility of online titer monitoring.