CHO cells fermentations

Process and yield optimization of mammalian cells / CHO cells

 

Increasing cell biomass by 35% and increasing the antibody titer by 100% by using a metabolite profiling-based strategy has previously been demonstrated for CHO cells (Sellick et al., Biotechnol. Bioeng. 2011).

 

Gupta et al. (Process Biochemistry, 2014) demonstrated the power of metabolite profiling in optimization of soy protein hydrolysates for enhanced and consistent cell culture performance.

 

Metabolite profiling of cell cultures will provide a detailed picture of the physiology.

  • Identification of depletion of compounds during growth (e.g. asparagine and ornitine in example below)
  • Identification of accumulation of compounds during growth (e.g. compounds at the top of figures below)
  • Comparison of growth conditions for different cultures/mutants or different fermentors/scales

 

Two different growth media and two different growth conditions of fed-batch cultures of CHO cells were compared using a GC-MS method which measures amino acids and other organic acids simultaneously. Around one hundred compounds were measured. Below are two figures:

1) A principal component analysis (PCA) of the results

2) Bar plots of 14 of the more than 70 metabolites that varied in concentration during the fermentations.

 

The PCA plot show the score plot on the left part of the figure. It shows how the metabolite profiles changes through the days. The fermentations start in the lower left quadrant and then moves right and upwards, with samples every second day just before feeding. Two of the fermentations end in the upper part of the figure, whereas the green fermentation did not seem to reach as far.

 

On the loading plot can be seen the compounds. The location of the plot indicates the highest concentration of the compounds. For example asparagine and ornithine are high in the start samples and depleted/almost depleted at the end of the fermentations. The compounds located near the end of the fermentations in the upper part of the figure are the compounds which accumulate during fermentation. Compounds that accumulate might be inhibitory to the fermentation or be supplied in excess in the growth media.

 

The bar plot shows the three diffrent fermentations in red, green and light blue and examples of some of the compounds measured. The samples were taken just before feeding on day 5, 7, 10, 12 and 14. The media were analyzed as well and are shown in dark blue (M1 to M4).