Functional genomics for rational bioprocess development with mammalian cell lines

Mammalian cell lines are the most important biological system for the production of therapeutic and diagnostic proteins with complex post-translational modifications. But their intrinsic cellular complexity confronts us with many challenges in the development of efficient bioprocesses.

Previous and Current Research

Despite all progress the development of fermentation processes with mammalian cells is to a large extend still based on empirical knowledge and historical experience. This is mainly due to missing qualitative and especially quantitative data and understanding of intracellular mechanisms under bioprocess conditions. Concomitantly there is an increasing economical and social interest in efficient processes for the production of bio‑pharmaceuticals to ensure the supply of the public with modern, highly efficient and safe therapeutic and diagnostic proteins. In microbial research the combination of classical biotechnological methods with functional genomics and bioinformatics has led to substantial progress in the rational development of high performance production strains and optimized fermentation processes. Due to the much higher complexity of mammalian cells these technologies have not been applied in cell culture technology, although the potential of these methods has been shown in an increasing number of scientific publications.

In this context we are working on the development and optimization of functional genomics techniques and their application in bioprocess and cell line development. This includes the sequencing of CHO cDNA (jointly with the University of Natural Resources and Life Sciences, Vienna) and the development of a proprietary CHO microarray, as well as the generation of a CHO proteom 2D-master gel and data base for the differential analysis of process parameters on the cellular proteom. We have successfully used this approach to identify the reasons for the increase in cell-specific productivity in substrate limited perfusion culture. For intracellular metabolomics several methods have been developed for a rapid and gentle quenching of the cellular metabolism based on microstructure heat exchanger or on filtration. Rapid quenching is necessary to conserve the intracellular metabolic situation of cells in bioprocesses until analysis. This has been used to investigate the influence of process conditions on the central metabolism and on the glycosylation machinery of production cell lines.

Future Projects and Aims

Our previous and current research provided us with the necessary tools to get a deep insight into pharmaceutical production processes on a cellular and molecular level, making it possible to identify targets for rational process optimization and cellular engineering. Our main focus will be on posttranslational modifications to unravel the reasons for macro- and microheterogeneity in protein glycosylation which should pave the way for more efficient processes resulting in more homogeneous products. Further targets are on inhibiting apoptosis to enhance maximum cell density and prolong cultivation time and on the increase in cell specific productivity. First successful attempts have been undertaken using a stable siRNA approach by lentiviral transduction of production cell lines.

Latest Publications of the Group