Strategic Framework for Parameterization of Cell Culture Models

Pavlos Kotidis,Cleo Kontoravdi

doi:10.3390/pr7030174

Abstract

Global Sensitivity Analysis (GSA) is a technique that numerically evaluates the significance of model parameters with the aim of reducing the number of parameters that need to be estimated accurately from experimental data. In the work presented herein, we explore different methods and criteria in the sensitivity analysis of a recently developed mathematical model to describe Chinese hamster ovary (CHO) cell metabolism in order to establish a strategic, transferable framework for parameterizing mechanistic cell culture models. For that reason, several types of GSA employing different sampling methods (Sobol’, Pseudo-random and Scrambled-Sobol’), parameter deviations (10%, 30% and 50%) and sensitivity index significance thresholds (0.05, 0.1 and 0.2) were examined. The results were evaluated according to the goodness of fit between the simulation results and experimental data from fed-batch CHO cell cultures. Then, the predictive capability of the model was tested against four different feeding experiments. Parameter value deviation levels proved not to have a significant effect on the results of the sensitivity analysis, while the Sobol’ and Scrambled-Sobol’ sampling methods and a 0.1 significance threshold were found to be the optimum settings. The resulting framework was finally used to calibrate the model for another CHO cell line, resulting in a good overall fit. The results of this work set the basis for the use of a single mechanistic metabolic model that can be easily adapted through the proposed sensitivity analysis method to the behavior of different cell lines and therefore minimize the experimental cost of model development.

Highlights

Mathematical models have been extensively used to describe mammalian cell metabolism and the production of therapeutic recombinant proteins, like monoclonal antibodies [1,2,3]
The emphasis was placed to the agreement of viable cell density (Xv) and antibody concentration to experimental data and these variables were used as the outputs of the sensitivity analysis
The significant parameters were re-estimated according to the feeding experiment with the lowest experimental standard deviation in terms of viable cell density and antibody concentration and their predictive capabilities were tested against the four feeding experiments with different concentrations of galactose and uridine

Summary

Introduction

Mathematical models have been extensively used to describe mammalian cell metabolism and the production of therapeutic recombinant proteins, like monoclonal antibodies (mAbs) [1,2,3]. Both genome scale and time-dependent metabolic mathematical models have been proposed to study the metabolic fluxes of mammalian cells. Sensitivity analysis quantifies how the variance of model inputs (parameters) affects the uncertainty of the model outputs (variables) [10]. It can be further categorized into local sensitivity analysis (LSA) and global sensitivity analysis (GSA).

Objectives

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Results

Conclusion