Hamburg University of Technology
Uwe Jandt has completed his PhD at the age of 28 years from doctoral studies at Philips Research Labs, Hamburg, Germany, in cooperation with University of Ulm, Germany. Presently, he is pursuing postdoctoral studies in systems biology and bioprocess engineering at Hamburg University of Technology. As a project leader, he is building a junior research group with focus on metabolic channeling in multi enzyme complexes. He has published more than 15 papers in reputed journals.
The behavior of cell cultures is determined by complex regulations and interactions, both on cellular level and within mixed populations. Heterogeneity in cell cultures is largely caused by the progress of the cell cycle. In order to elucidate cell-cycle dependent regulations in cell cultures, it is desirable to synchronize a culture with minimal perturbation, cultivate it under physiological conditions and apply subpopulation-resolved analysis and modeling approaches. One main critical point is to define a suitable synchronization method that both preserves physiological conditions and achieves high yield to enable further cultivation in bioreactor scale (i.e. at least 1 L). Common chemical methods, like double thymidine block, serum starvation and others, are suspected – or even proven – to not yield accurately synchronized cultures or to otherwise interfere with cell physiology. Membrane elution, also referred to as ”eukaryotic baby machine” provides extremely accurately synchronized cells, but with low yield. We use countercurrent-flow centrifugal elutriation as a reliable physical selective synchronization method and demonstrate the successful adaptation of cell-cycle dependent population balance ensemble model on mammalian producer suspension cell lines (CHO-K1, human AGE1.HN, and HEK293s). We show how to obtain reliable phase-specific parameters with high significance and thereby how to quantitatively determine the accuracy of synchronization and verification or falsification of actual phase-dependency of certain cellular processes. These are for example lactate by-production or the regulation of central metabolic switches as represented by the pyruvate dehydrogenase complex (PDC). In this context, we also focus on specific preconditions to judge the validity of the applied synchronization procedure and subsequent analysis.