Dynamic Model of Chinese Hamster Ovary Cell Metabolism in Fed-Batch Culture.
Abstract: In this work,
the design and execution of a mechanistic metabolic model is presented that is capable
of simulating extracellular metabolite concentration profiles, particularly cell density
and antibody titer, throughout the course of a recombinant protein producing CHO
fed-batch culture. In Chapter 2, formulation of a reaction network is described wherein
a genome scale metabolic ... read morereaction network is systematically reduced in size through the
use of graph theory and elementary flux modes methodologies, resulting in a smaller but
biochemically comprehensive network that can be used for dynamic kinetic modeling. In
Chapter 3, a dynamic model structure is described that builds upon a dynamic flux
balance analysis framework, whereby 12 intracellular cytosolic reactions are defined
with convenience kinetic rate expressions and the remaining 22 intracellular and
exchange reactions are calculated from mass balances around the assumed pseudo-steady
state intracellular metabolites. The unique aspects of the model formulation that are
vital to achieving accurate dynamic predictions include: (1) defining intracellular
cytosolic reactions with kinetic rate expressions that are based on the associated
extracellular metabolite concentrations, and (2) defining a redox variable to
accommodate the effect of NADH on reaction rate kinetics. Application of the model is
the demonstrated by predicting the effect of process variable changes (e.g. temperature,
seed density, nutrient concentrations) on the resulting metabolic dynamics of a CHO
fed-batch culture. In Chapter 4, further application of the model is demonstrated by
simulating the metabolic responses of genetic modulations (e.g. up- or down-regulation),
independently, but more importantly, in conjunction with process variable changes.
Optimal operating conditions for both process and genetic variables are determined for
producing improved quantity and quality of recombinant protein. Overall, the dynamic
metabolic model serves as a powerful tool to aid laboratory experiments, providing
savings in time, money, and resources, as well as an improved understanding of the
biochemical mechanisms driving the processes.
Thesis (Ph.D.)--Tufts University, 2011.
Submitted to the Dept. of Chemical and Biological Engineering.
Advisor: Kyongbum Lee.
Committee: Christos Georgakis, Soha Hassoun, and Wenge Wang.
Keyword: Chemical Engineering.read less