October 18-21, 2015
During the last decade, single-use bioreactors or storage vessels made of flexible bags have been well-established in biopharmaceutical production. However, some developers and producers of biopharmaceuticals refuse their usage because of potential interactions of the plastic material with cells and proteins. Most dreaded apart from extractables are leachables (such as bDtBPP ), that derive from additives and are formed during the bag manufacturing process or gamma sterilization. Leachables can migrate from the film contact layer into the process fluid under process conditions and can inhibit cell growth or impair product quality. A further reason for cell growth limitations can be the adsorption of hydrophobic medium components (like fatty acids or cholesterol ) to the contact layer of the polyethylene film. Consequently, there is a high demand for the early identification of critical film types. For this purpose, the usage of sensitive and commercially available cell lines is favorable. A new standardized cell-based assay has been recently published by DECHEMA , which allows general recommendations and a comparison of different film materials by means of cell growth studies with sensitive CHO cell lines and a chemically defined minimal culture medium.
In our case study, we adopted and extended the DECHEMA method in order to evaluate a new single-use bag material versus a negative control bag. The new film type has a minimized concentration of TBPP, which is known to degrade to the toxic leachable bDtBPP. In contrast, the TBPP concentration was 30-fold higher in the contact layer of the negative control bag. We investigated the growth performance for different animal and human cell lines (CHO cells, hybridoma, insect cells, and human mesenchymal stem cells) which are relevant for biopharmaceutical production processes. Additionally, the adsorption of hydrophobic medium components to the film contact layer was examined in one experiment.
Within our study, the new film type did not show any negative impact on cell growth for CHO and hybridoma cells grown in chemically defined media, Sf-9 cells cultivated in serum-free medium and human mesenchymal stem cells expanded at serum-reduced conditions. By contrast, the negative control film resulted in considerable cell growth inhibition with deviations in viable peak cell densities of 15 % to 69 %.
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