Metabolic profiling and imaging of CHO cells for fusion protein production

UoM administered thesis: Phd

  • Authors:
  • Ewa Szula

Abstract

Fc-fusion proteins (e.g. EPO-Fc) are the most often created fusion proteins due to their beneficial biological and pharmacological properties. The economic success of Fc-fusion proteins and other biopharmaceuticals production however, greatly depends on a robust, low-cost and highly effective protein mammalian cell extraction system . Understanding of how cells respond to a protein production environment based on metabolic profiles provides new goals for bioengineering of cell lines for best performance in biomanufacturing. Furthermore, insights on how individual cell metabolism and therefore phenotype, respond to cell microenvironment allows the underlying biological mechanisms to be explored in greater detail. This study focused on the application of mass spectrometry (MS) technologies, combining the analysis of metabolic profiles of cells extracts by GC-MS and MALDI-MS and spatial visualisation and distribution of metabolites within cells producing the fusion protein by MALDI-MSI and SIMS imaging. The analysis of external and internal metabolome profiles of cells producing the protein showed an extended effect of EPO-Fc fusion protein production on cell metabolism. The findings indicate that changes observed in EPO-Fc producing cells are related to enhanced protein and lipid synthesis highlighting that these cells are in a state of increased metabolic activity with the protein exocytosis into growth medium. Moreover, the composition of lipid bilayer of induced cells seemed to be different to non-induced cells. These findings were confirmed with the analysis of EPO-Fc induced cells using MS metabolic imaging. Multivariate analysis highlighted a number of metabolites that were significantly influenced by the protein expression when compared to control cells. The major metabolic changes in induced cells were those related to lipid metabolism. The information about metabolic changes in tetracycline-induced cells obtained from the analysis of cell populations was further supported with the analysis based on single-cell studies. Single-cell based studies also proved that investigations of individual cells provide additional insights about changes in metabolism of induced cells that can be referred to a unique, single cell and its phenotype. The analysis of CHO cells revealed a high level of heterogeneity within a cell population. Different cell phenotype and hence, metabolite content allowed for correlation between cell locations and their metabolite characteristics, specific for each type of cells. This project has successfully shown combination of bio-analytical techniques to investigate external and internal metabolome changes related to a fusion protein production in mammalian cells. Additionally, the significance of single cell approaches in metabolomics has also been highlighted, providing insights into the sub-cellular distribution of metabolites in cells producing EPO-Fc and information on the level of heterogeneity within a cell population. A multidimensional approach for metabolic profiling and future technological improvements of single-cell platforms are required to provide improved data acquisition and data analysis in order to better understand unknown processes involved in cell metabolism.

Details

Original languageEnglish
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Award date31 Dec 2017