With Many Newer CHO Cell Lines Available, Why Does Sartorius Continue to Use the CHO DG44 Variant?
A variety of CHO cell lines are used as hosts in the production of biologics. Why did we select the CHO DG44 variant for our cell line development service?
This article is posted on our Science Snippets Blog
Chinese hamster ovary (CHO) cells are a popular host for the production of biotherapeutics. Their enduring safety record, rapid growth, and ability to generate high product yields make them ideal for the commercial production of a wide range of biologics. There are multiple varieties of CHO cell lines constantly emerging to solve different challenges in the biopharmaceutical industry.
Sartorius has established a robust and scalable cell line development platform based on the CHO DG44 cell line.
CHO DG44 Cells – What are They?
CHO DG44 cells are derived from the original CHO cell line, which was first established in the 1950s. The key difference between the CHO DG44 line and the original is that, in CHO DG44 cells, both copies of the DHFR gene have been eliminated. The DHFR gene is responsible for the production of dihydrofolate reductase, an essential enzyme for cellular metabolism. Cells lacking this protein require glycine, hypoxanthine, and thymidine to grow in culture.
Omitting one or more of these supplements from the media means the cells will not be able to grow. That is, unless you provide them with a functional copy of the DHFR gene while transfecting cells with the gene of interest.
The cells that have been successfully transfected with the gene of interest will also receive the DHFR gene and grow in culture. Those without the gene of interest and the DHFR gene will be unable to grow. This represents a stringent selection method and is why CHO cells lacking DHFR are the most commonly used hosts for protein production.
Multiple CHO cell lines have emerged since the creation of the CHO DG44 line. Each offers unique advantages and is typically tailored to a particular biologic or group of biologics. For example, to enable post-translational modifications or promote the secretion of an extracellular protein. Below, we discuss why Sartorius uses the CHO DG44 variant for our CHO cell line development platform.
Features of CHO DG44 Cells
Proven Track Record
CHO DG44 cells have been a workhorse in the production of biopharmaceuticals (such as monoclonal antibodies and other recombinant proteins) for several decades. Their traits are well-characterized, and they have a fully-documented history. This makes CHO DG44 cells ideal for demonstrating biosafety according to regulatory requirements.
Supported by Tailor-Made Growth Media
The CHO DG44 cell line has been adapted to serum-free, chemically-defined cell culture media and suspension growth. Our proprietary 4Cell® XtraCHO Media System was specifically developed to culture CHO DG44 cells without proteins or animal-derived components. The growth conditions mean the cells are metabolically optimized for stable growth over long periods, ideal for generating high protein yields and maintaining genetic integrity.
Ideal for Large-Scale Production
CHO DG44 cells are highly productive, facilitating the manufacture of high product titers. They are also stable in long-term culture (Figure 1), which is an acute concern when growing immortalized cell lines. Together, these features make CHO DG44 cells ideal for the synthesis of biologics on an industrial scale.
Figure 1 - CHO DG44 cells maintain high cell viability even after 200 passages
Stringent and Safe Selection
Sartorius CHO DG44 cells are based on a DHFR selection system. DHFR is expressed at very low levels, enabling highly stringent selection and increasing the probability of isolating high-producing clones after selection.
Often, CHO DG44 cells are subject to selection through the use of methotrexate (MTX), which is toxic and can cause genome instability. It must be removed from the product, and you must demonstrate that no trace amounts remain. Instead, we perform a metabolic selection, avoiding the need to introduce MTX into your process.
Supporting Plug-and-Play CHO Cell Line Development
CHO DG44 host cells are the foundation of our cell line development service. Our expert insights and specially designed growth media support the scalability and rigorous selection potential of CHO DG44 cells. Their reliability is demonstrated by their extensive track record. These features enable us to offer a low-risk service with rapid development timelines and performance success.
