Dynamic analysis of GS‐NS0 cells producing a recombinant monoclonal antibody during fed‐batch culture

In this study we have analyzed the dynamic covariation of the mammalian cell proteome with respect to functional phenotype during fed‐batch culture of NS0 murine myeloma cells producing a recombinant IgG4 monoclonal antibody. GS‐NS0 cells were cultured in duplicate 10 L bioreactors (36.5°C, 15% DOT, pH 7.0) for 335 h and supplemented with a continuous feed stream after 120 h. Cell‐specific growth rate declined continuously after 72 h of culture. Cell‐specific recombinant monoclonal antibody production rate (qP) varied sixfold through culture. Whilst qP correlated with relative recombinant heavy chain mRNA abundance up to 216 h, qP subsequently declined, independent of recombinant heavy chain or light chain mRNA abundance. GS‐NS0 cultures were sampled at 48 h intervals between 24 and 264 h of culture for proteomic analyses. Total protein abundance and nascent polypeptide synthesis was determined by 2D PAGE of unlabeled proteins visualized by SYPRO® Ruby and autoradiography of 35S‐labeled polypeptides, respectively. Covariation of nascent polypeptide synthesis and abundance with biomass‐specific cell growth, glucose and glutamate consumption, lactate and Mab production rates were then examined using two partial least squares regression models. Most changes in polypeptide synthesis or abundance for proteins previously identified by mass spectrometry were positively correlated with biomass‐specific growth rate. We conclude that the substantial transitions in cell physiology and qP that occur during culture utilize a relatively constant complement of the most abundant host cell machines that vary primarily with respect to induced changes in cell growth rate. Biotechnol. Bioeng. 2007;97: 410–424. © 2006 Wiley Periodicals, Inc.