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Model-based strategy for cell culture seed train layout verified at lab scale
BMC Proceedings volume 9, Article number: P44 (2015)
Production of biopharmaceuticals for diagnostic and therapeutic applications with suspension cells in bioreactors requires a seed train up to production scale . For the first steps - the transitions between T-flasks, tubes, roller bottles, shake flasks, stirred bioreactors or single-use reactors - the experimental effort to lay-out these steps is high. At the same time it is known that the first cultivation steps have a significant impact on the success or failure in production scale. A software tool has been developed which provides possibilities for simulation, analysis and design of seed trains . Tool structure:
A kinetic model. In this case a simple unstructured model where kinetic parameters can be obtained from a few experiments only.
A Nelder-Mead-algorithm to determine model parameters.
A developed MATLAB software tool able to determine optimal points in time or viable cell concentrations for transfer into the next scale.
The successful application for the cell line (AGE1.HN AAT , ProBioGen AG) has been shown previously . Here the tool was tested for a suspendable CHO cell line.
Materials and methods
The cell line CHO-K1 has been grown in chemically defined TC-42 medium (TeutoCell AG, Bielefeld, Germany), 4 mmol L-1 glutamine.
Data for parameter identification for the kinetic mode were determined in shake flask cultures. The seed train steps were: 1. culture tube (0.0025 L), 2. shake flask (0.070 L), 3: Labfors 5 Cell (2 L).
For the seed train first different optimization criteria were compared in silico (Fig. 1a). Finally, the average of time at maximal space-time-yield (STY) and time at 90% of maximal growth rate (0.9·µmax) was used as optimization criterion for cell transfer. The concept was tested successfully up to a 2 L scale for 3 scale-up steps (Figure 1b).
The concept offers a simple and inexpensive strategy for design of seed train scale-up steps. The results for the lab scale steps show that the tool was able to perform a seed train optimization only on the basis of two batches, the underlying model and its parameter identification.
The bioreactor (Labfors 5 Cell) was kindly provided by the company Infors AG, the suspendable cell line CHO-K1 by Prof. Thomas Noll, University of Bielefeld.
Eibl R, Eibl D, Pörtner R, Catapano G, Czermak P: Cell and Tissue Reaction Engineering. Springer. 2008, ISBN 978-3-540-68175-5
Kern S, Platas-Barradas O, Pörtner R, Frahm B: Model-based strategy for cell culture seed train layout verified at lab scale. Cytotechnol. published online: 21 March 2015, DOI 10.1007/s10616-015-9858-9
Kern S, Platas O, Schaletzky M, Sandig V, Frahm B, Pörtner R: Model-based design of the first steps of a seed train for cell culture processes. BMC Proceedings. 2013, 7 (Suppl 6): P11-(4 December 2013)