Considerations of the Impacts of Cell-Specific Growth and Production Rate on Clone Selection—A Simulation Study

Tanja Hernández Rodríguez,Björn Frahm,Florian M Wurm,Sophie Morerod,Ralf Pörtner

doi:10.3390/pr9060964

Abstract

For the manufacturing of complex biopharmaceuticals using bioreactors with cultivated mammalian cells, high product concentration is an important objective. The phenotype of the cells in a reactor plays an important role. Are clonal cell populations showing high cell-specific growth rates more favorable than cell lines with higher cell-specific productivities or vice versa? Five clonal Chinese hamster ovary cell populations were analyzed based on the data of a 3-month-stability study. We adapted a mechanistic cell culture model to the experimental data of one such clonally derived cell population. Uncertainties and prior knowledge concerning model parameters were considered using Bayesian parameter estimations. This model was used then to define an inoculum train protocol. Based on this, we subsequently simulated the impacts of differences in growth rates (±10%) and production rates (±10% and ±50%) on the overall cultivation time, including making the inoculum train cultures; the final production phase, the volumetric titer in that bioreactor and the ratio of both, defined as overall process productivity. We showed thus unequivocally that growth rates have a higher impact (up to three times) on overall process productivity and for product output per year, whereas cells with higher productivity can potentially generate higher product concentrations in the production vessel.

Highlights

For the production of certain biopharmaceuticals, animal cells have to be expanded from a frozen vial
("production rate" or "specific productivity") on overall product yield using parameters such as time needed for the inoculum train cultures, the volumetric titer during final production phase and the overall process productivity (=Space-Time-Yield: volumetric titer in production/overall cultivation time, including inoculum train)
For all three cell lines, a prediction model of an inoculum train, including predictive uncertainty arising from model parametric uncertainty, has been utilized

Summary

Introduction

For the production of certain biopharmaceuticals, animal cells have to be expanded from a frozen vial. Questions and issues remain to be solved to maximize their utility, since CHO cells have a very wide range of genotypic diversity and corresponding phenotypic differences [4,5,6]. This is quite obvious when clonally derived cell populations from a single transfection are compared against each other. These phenotypic differences have impacts on growth-related characteristics, cellspecific productivity and the quality of the final product (e.g., glycosylation patterns) [6,7]. For the testing of the genetic and production stability, clonally derived cell lines, in the following referred to as “clones” or “clonally derived cell populations”, undergo typically stability studies which can last up to six months

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