Novel scale-up strategy based on three-dimensional shear space for animal cell culture

Abstract

Animal cell cultivations are widely used for producing antibodies, vaccines, and recombinant protein drugs. However, the extreme sensitivity of animal cells to hydrodynamic stress often hinders its scale-up in large-scale stirred tank bioreactors. This study introduced a new scale-up strategy based on three-dimensional (3D) shear space for large-scale animal cell culture. First, the shear environments of bioreactors ranging from lab-scale (7.5 and 42 L) to industrial-scale (30, 90, 350, and 1000 L) were quantitatively analyzed through computational fluid dynamics (CFD) methods and successfully validated by particle image velocimetry (PIV) experiments. Moreover, the quantitative relationships between shear parameters (including shear rates in the impeller and tank zone, overall average shear rate, and maximum shear rate) and impeller tip velocity were established. In addition, a correlation analysis between shear-related parameters and viable cell densities in Spodoptera frugiperda Sf9 cultivations indicated that shear rates in the impeller and tank zone, and the overall average shear rate were the three key shear parameters required for scale-up. Further, an optimized 3D operation space for shear rate was established according to the three key shear parameters obtained under preferable operation conditions in lab-scale bioreactors. Based on the results, agitation rates in large-scale bioreactors were determined using the proposed correlation. Ultimately, we achieved successful scale-up of Spodoptera frugiperda Sf9 in industrial bioreactors with volumes up to 1000 L using this strategy. Thus, this study introduces a highly efficient and economical scale-up strategy for shear-sensitive cells.