Cell line development using the SEFEX system
© Greulich et al; licensee BioMed Central Ltd. 2011
Published: 22 November 2011
Cell lines producing biopharmaceuticals with high yield and high quality in a regulatory compliant environment are a prerequisite for cost effective bioproductions. The development of these production cell lines often includes screening strategies combined with gene amplification and limited dilution experiments, a time consuming process. Especially gene amplification tends to interfere with clonal stability. Limited dilution, especially using a serum-free culture environment is prone to failure and low clone yields.
We present here the SEFEX platform technology for the development of non-amplified high yield production cell lines. The strategy is based on a regulatory compliant method for transfection and single cell cloning using a proprietary, fully tested, CHO-K1 host cell line adapted to chemically defined medium. Fast track cell lines were generated by selection of single cell derived clones within 2.5 months after transfection. 1.0 g/L product concentration were achieved after two rounds of process development using these cell lines. Optimized cell lines were developed based on fast track cell lines employing a second transfection. These cell lines were capable for production of 2.6 g/L during an early phase of process development.
Cell specific productivity and product concentration obtained with fast track cell lines and optimized cell lines.
specific productivity [pg/cell/day]
product concentration fed-batch [g/L]
fast track cell line
optimised cell line
fast track cell line
optimised cell line
1 (IgG A)
2 (IgG B)
3 (IgG C)
Figure 1 shows growth curves of the fast-track and optimized cell line producing IgG B. Optimization of maximum viable cell density was not addressed during upstream process development so far. This optimization is currently ongoing and leaves room for further improvements. Specific productivity of the optimized cell lines varied between 18 and 36 pg/c/d, which was equivalent to a two- to six-fold improvement compared to the fast track cell lines. Productivity was suitable for production of high volume products. Scale-up to 300 L stirred tank and 1000 L wave bioreactor for production of clinical phase II drug product was shown for production cell lines generated with the SEFEX platform technology.
The SEFEX platform technology for the development of non-amplified high yield production cell lines is based on a regulatory compliant, proprietary CHO-K1 host cell line adapted to chemically defined medium. Fast track cell lines, which were available within 2.5 months produced 1.0 g/L product. Optimized cell lines, which were developed based on fast track cell lines, were capable for production of 2.6 g/L in early phase of process development. Using the SEFEX platform technology, all development steps were carried out under entirely serum-free or chemically defined media conditions including transfection, selection, and single cell cloning. Clonality was assured and documented in a regulatory compliant manner using photo documentation of single cells in cell cloning experiments. The serial transfection cell line development strategy described here provides the possibility to develop production cell lines meeting industrial demands employing simplest process development procedures within minimized time frames.
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