Mammalian cells

Why Mammalian cells? - Mammalian cells as cell factories
The potential in biopharmaceuticals produced by mammalian cells is huge (1). Last year the global biopharmaceutical market in 2015 was expected to increase to US$ 167 billion (2). The biopharmaceuticals target diseases such as psoriasis and cancer and are more convenient, safe and effective than the other treatment solutions on the market (3). Compared to microbes mammalian cells have lower yields, are more difficult to handle in the laboratory, are costly and have a slow doubling time. So why use mammalian cells, when microbes such as yeast and E. coli are already used as fast, efficient, and cheap cell factories?
The main and most important answer to this is post-translational modifications (PTMs) (4). The reasons for the importance of the PTMs are the protein stability, ligand binding, and potential result in increased immunogenicity when used for humans (4). Most of the therapeutic proteins approved and currently in development are post-translationally modified, which is not surprising since approximately 50% of human proteins are glycosylated (5,5).

With this kept in mind there are some key issues in manufacturing where speed in development plays a prominent role. Cell line creation has to be complete as rapidly as possible and to reduce the timelines for cell line creation the Plug’n’Play with DNA assembly standard could be a valuable tool.

It is not only in the industry a more efficient high throughput cloning system could be valuable, also when it comes to constructing DNA libraries from extremely complex DNA populations such as total human genomic DNA it would be useful.

To demonstrate how fast you can assemble any vector of choice for the expression in mammalian cells we chose to design a reporter system as proof of concept. This system comprises a backbone plasmid that allows for the amplification in and selection of E. coli, the strong constitutive promoter CMV, a gene module consisting of a gene encoding a fluorescent protein or a gene encoding a fluorescent protein and a localization signal, the BGH terminator and the hygromycin marker cassette. On this page we present the results of the reporter system. In total we spent blabla days on constructing, blabla days on transfecting and went from design to result in blabla days

pJEJAM1

The results shows fluorescence spread evenly in the hyphae which correlate with that in device BBa_K678060, the gene of interest, only consists of a green fluorescence protein GFP with no specific target.

Aspergillus nidulans with device BBa_K678060 - DIC light.	Aspergillus nidulans with device BBa_K678060 - GFP light.

Aspergillus nidulans with device BBa_K678060 - Front	Aspergillus nidulans with device BBa_K678060 - Back

References

(1) Hesse, F., Wagner, R. (2000). Developments and improvements in the manufacturing of human therapeutics with mammalian cell cultures. TIBTECH, 18, 173-180.

(2) Global Biopharmaceutical Market Report (2010-2015). (2010). The International Market Analysis Research and Consulting Group.

(3) Xie, L., Zhou, W., Robinson, D. (2003). Protein production by large-scale mammalian cell culture. S.C. Makrides (Ed.) Gene Transfer and Expression in Mammalian Cells. Elsevier Science B.V.

(4) Browne, SM., Al-Rubeai, M. (2007). Selection methods for high-producing mammalian cell lines. TRENDS in Biotechnology, 25, 425-432.

(5) Walsh, W., Jefferis, R. (2006). Post-translational modifications in the context of therapeutic proteins. Nature Biotechnology, 24, 1241-1252.