Mammalian Cell Expression – Why Is It So Useful in Biotechnology?

Mammalian cell expression refers to the process of introducing and expressing foreign genes or proteins in mammalian cells. Mammalian cells, such as human embryonic kidney (HEK) cells, Chinese hamster ovary (CHO) cells, and mouse fibroblast cells, are commonly used for the production of recombinant proteins and biopharmaceuticals.

There are several reasons why mammalian cell expression systems are preferred for the production of complex proteins. Mammalian cells can perform post-translational modifications such as glycosylation, phosphorylation, and proteolytic processing, which are crucial for the proper folding and function of many proteins. These modifications can significantly affect the biological activity, stability, and immunogenicity of the expressed protein.

Mammalian cell expression systems also offer advantages in terms of protein yield and scalability. They can produce large quantities of recombinant proteins, making them suitable for industrial-scale production. Additionally, mammalian cells can secrete proteins directly into the culture medium, simplifying downstream processing and purification.

There are various methods used to introduce foreign genes into mammalian cells for expression. The most common method is transient transfection, where the gene of interest is delivered into the cells using a plasmid or viral vector. The introduced DNA is typically transiently expressed, meaning it is not integrated into the host cell genome and will be gradually diluted as the cells divide.

For stable expression, the gene of interest can be integrated into the host cell genome using techniques such as plasmid-based selection or viral-mediated gene transfer. Stable expression allows for long-term production of the desired protein.

Several factors should be considered when choosing a mammalian cell expression system, including cell line compatibility, growth characteristics, protein yield, and post-translational modification capabilities. Different cell lines have distinct advantages and disadvantages, so the selection of the appropriate cell line depends on the specific requirements of the protein being expressed.

In recent years, advancements in genetic engineering technologies, such as CRISPR/Cas9-mediated genome editing, have further enhanced the capabilities of mammalian cell expression systems. These techniques enable precise modification of the host cell genome, allowing for the creation of cell lines with enhanced protein expression or modified post-translational modification pathways.

Generally then, mammalian cell expression systems are widely used in biopharmaceutical and biotechnology industries for the production of recombinant proteins due to their ability to perform complex post-translational modifications and generate large quantities of bioactive proteins.