Effect of process parameters and product-host-interaction on hVEGFA-production by recombinant Chinese hamster ovary cells

A potential producer clone was identified among recombinant, human vascular endothelial growth factor A (hVEGFA)-producing Chinese Hamster Ovary (CHO) K1 cells, using a recently established screening method. In batch spinner cultivations, the cells showed a maximum growth rate of 0.045 h-1, a final total cell density of 5.3 x 10(6) mL-1 (living cell density: 3.4 x 10(6) mL-1), and a final hVEGFA concentration of 207 mu g L-1. Living cell density and productivity in the spinner cultivations could be increased by glutamine feeding. Transfer of the process to the bioreactor (batch mode, control of pH, T, and O2) resulted in a reduction of the growth rate by roughly 50%, while overall living cell density and productivity increased, largely due to an extension of the production phase. When the bioreactor was run in the fed-batch mode, growth rates were further reduced, while productivity and living cell densities reached a maximum (hVEGFA: 358 mu g L-1, cells: 5.2 x 10(6) mL-1). In addition, the death rate of the hVEGFA-producing cells was considerably reduced compared with the parent cell line, most likely due to product-host-interaction. This hypothesis was corroborated when a second recombinant CHO cell line (antibody producer) was transfected with the hVEGFA gene and afterward consistently showed higher viable cell densities together with a significantly improved antibody titer. (C) 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2012