Mammalian cells
Using mammalian cells for protein production allows us to produce proteins with the full complexity of native human proteins, a necessity for a very large amount of biomedically relevant proteins. PPS offers a versatile protein production platform for mammalian cells that can produce from milligrams to grams of protein using both flexible and high throughput production systems. The services that are offered by PPS include everything from initial consultation and construct generation to final delivered product.
Producing proteins in mammalian cells offers several advantages due to their natural compatibility with human-like protein folding and post-translational modifications. Biomedically relevant proteins are often complex in terms of subunit composition, disulfide bonds and post-translational modifications such as phosphorylation, sulfation, and different types of glycosylation. Expressing them in mammalian cells ensures that the produced proteins are functional and biologically active in a manner similar to endogenous human proteins [1].
Two commonly used mammalian cell lines used for protein production are the Chinese Hamster Ovary cells (CHO) and Human Embryonic Kidney cells (HEK293). CHO cells are often used to produce biopharmaceuticals for human use, for example therapeutic antibodies, while HEK293 has good properties for producing secreted and trans-membrane proteins 1,2. However, both CHO and HEK293 cell lines have their strengths and weaknesses, and the choice of production cell line will depend on factors such as the specific protein being produced, the desired post-translational modifications, scalability requirements, and intended use of the product.
What PPS offers:
Protein production can be done via transient transfection of common production strains such as CHO and HEK293 cells or via stable clones or hybridomas expressing the target proteins. PPS also offers a service of making stable mammalian cell lines expressing either secreted or cell-associated proteins, which can be used for protein production or other research by the user. For secreted proteins transient transfection is often the choice for protein production as it is relatively quick, cheap and results in yields sufficient for most users.
Stable clones are more often useful when large or frequent batches are desired.
Our protein production pipeline is flexible and can accommodate projects involving high customization in terms of expression, tags, labeling, purification strategies and production endpoints, but also more streamlined high throughput productions. A normal project often includes initial small-scale trials to evaluate project feasibility. PPS can culture cells in volumes ranging from 50 mL to 30 L in shake flasks and up to 20L in WAVE bioreactors and stirred tank perfusion bioreactors. This enables us to produce both small and large amounts of proteins (milligrams to grams) which can be used for research or to set up pilot projects for industrial-scale bioprocesses (Figure 1).
As protein glycosylation can have significant implications on the structure, function, stability and antigenicity of proteins 1,3 PPS also offer the production of some glycosylation variants such as CHO-mutant Lec3.2.8.1 and 293 GnTI- which produce high mannose N-glycans [4]. If the cells are not the deliverable itself, this is followed by subsequent protein purification and characterization.
Figure 1.
Different production scales
1. Lalonde, M.-E. & Durocher, Y. Therapeutic glycoprotein production in mammalian cells. J. Biotechnol. 251, 128–140 (2017).
2. Tan, E., Chin, C. S. H., Lim, Z. F. S. & Ng, S. K. HEK293 Cell Line as a Platform to Produce Recombinant Proteins and Viral Vectors. Frontiers in Bioengineering and Biotechnology vol. 9 (2021).
3. Goh, J. B. & Ng, S. K. Impact of host cell line choice on glycan profile. Crit. Rev. Biotechnol. 38, 851–867 (2018).
4. Büssow, K. Stable mammalian producer cell lines for structural biology. Curr. Opin. Struct. Biol. 32, 81–90 (2015).