Recombinant monoclonal antibody production
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Transient antibody production is a fast method for the short-time expression of the immunoglobulin heavy chain and light chain in host cells. Especially helpful for research and diagnostics purposes, the production of recombinant antibodies using immortalized human embryonic kidney cells (HEK293) or Chinese hamster ovary cells (CHO cells) through transient antibody expression bears a lot of potential for drug manufacturing.
In the following, we will take a closer look at transient antibody production, its definitions, how it works and its importance for the pharmaceutical industry.
Transient antibody production is defined as the production of antibody variants, involving transient transfection instead of cultured cell lines for expression. This leads to faster production rates because no producer cell lines must be generated. Transient antibody production is often used for small-scale research projects that rely on a fast turnaround time. However, new advances in transient antibody production in mammalian cells allow for large scale antibody expression.1
Read more: What is transient transfection? | Benefits of transient transfection
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The two kinds of transfection, stable transfection and transient transfection, bear differences in their application and effects. While in stable transfection plasmid DNA is integrated into the cellular genome, it also enters the cell during transient transfection, but does not integrate into the cellular genome. As a consequence, the transfected DNA will only be expressed for a short amount of time and not passed on to next generations.
Read more: Stable vs. transient transfection
Transient transfection is a step in the production of antibodies in various types. One variation of this method is the expression of monoclonal antibodies (mAbs) in vivo with the help of viral vectors, which has played an important role in the development of vaccines for different diseases, including Covid-19.
Further, transient transfection is also used for in vitro antibody production with cell lines that have been cultured in the lab. Especially in transient recombinant antibody production, it is not necessary to work with in vivo conditions, which makes it possible to perform recombinant antibody expression without a living host. As stated before, transient transfection is mostly used for small-scale antibody expression. However, by using modified HEK293 and CHO cells as host cell lines, large-scale expression of bispecific antibodies can be achieved in these systems as well.
When it comes to transient expression, which cell line should you choose? Mammalian expression cell lines like HEK or CHO cells are able to perform correct folding and post-translational modifications, which means they are both suitable for mammalian transient expression systems. Both cell lines are able to produce proteins that are similar to proteins produced by humans and show high cell viability levels.
HEK293 cells are able to generate glycosylation profiles that are similar to human profiles, which makes them suitable for recombinant protein production. Furthermore, high cell division rates qualify them for the use in biotherapeutics.
CHO cells have a high transfection efficiency and are easy to culture. It is possible to produce large amounts of recombinant protein by using CHO cells. In comparison to HEK293, which are of human descent, they show lower toxicity levels and are less susceptible to human viruses.2
CHO cells bring several advantages to the transient expression of recombinant antibodies. Furthermore, there are several new approaches that make this expression system not only feasible for small, but also for large-scale high-throughput antibody expression, which adds to the popularity of Chinese Hamster Ovary cells in rAb production. In fact, when looking at the roughly 40 novel antibody molecules every year that start being investigated in clinical trials, it is noteworthy that the majority is produced in CHO cells.3,4
There are different steps that are involved in transient recombinant antibody expression. At first, a host cell line is cultured in vitro. The most common mammalian cell lines used for recombinant antibody production are immortalized human embryonic kidney cells (HEK293) or Chinese hamster ovary cells (CHO cells) as they are able to perform high-throughput recombinant protein expression with post translational modifications and native folding qualities.
After the cells have been cultured, an amino acid sequence or gene with specific qualities is inserted into the cell’s membrane to lead it to express a specific antibody with desired isotypes. This can be achieved through a biological transfection method where nucleic acids are delivered to the cell membrane by viral vectors or through a chemical or physical transfection method. The main challenge while performing the aforementioned transfection production methods is to not damage the eukaryotic cell in the process, which would lead to its death.5
A very common chemical transient transfection method that is often used in transient antibody expression is PEI-mediated transfection, which involves the use of plasmids and oligonucleotides.
To get a better understanding of the mechanisms involved in transient production, we have listed the different steps below.
The main advantages of transient antibody expression are the rapid expression rates and high protein production over a short amount of time. Cells express the transient transfected antigen for a limited amount of time and antibodies are easy to culture from serum-free medium. They are usually lost after cell division.
Transient transfection is a very useful method for diagnostics or antibody characterization.6 This allows for quick results in the study of receptor proteins, for example. Cells can be harvested as soon as one to three days after transfection, depending on the cell type and expression gene.
We are a leading service provider for recombinant antibody production. Get in contact!
Transient transfection is an important tool for research projects. However, new challenges like the Covid-19 pandemic have shown that the demand for rapidly produced antibodies on a larger scale is going up.7 Through new advances in biotechnology and the optimization of expression serums, expression vectors, peptides, expression cells and higher titers, transient recombinant production with its short development timeline has the potential to fill this need without having to depend on stable cell lines.
Transient protein expression is not only important for drug discovery and antibody engineering, it also helps to fill the high demand for therapeutic antibodies.
As recombinant protein production is a laborious process that requires expertise and the right equipment, many pharmaceutical companies rely on contract research organizations for transient gene expression.
When it comes to transient expression, which cell line should you choose? Mammalian expression cell lines like HEK or CHO cells are able to perform correct folding and post-translational modifications, which means they are both suitable for mammalian transient expression systems. Both cell lines are able to produce proteins that are similar to proteins produced by humans and show high cell viability levels.
HEK293 cells are able to generate glycosylation profiles that are similar to human profiles, which makes them suitable for recombinant protein production. Furthermore, high cell division rates qualify them for the use in biotherapeutics.
CHO cells have a high transfection efficiency and are easy to culture. It is possible to produce large amounts of recombinant protein by using CHO cells. In comparison to HEK293, which are of human descent, they show lower toxicity levels and are less susceptible to human viruses.2
Read more: Transient antibody expression in CHO cells: Our approach at evitria
We believe that the future of transient transfection is full of potential. By using CHO-cells as our cell line of choice for our transient recombinant antibody expression service, we are able to deliver antibodies in less than five weeks. And as they have originally been harvested decades ago and cultured since then, no animals are directly involved in antibody production in CHO cells.
Through our custom antibody production, we can deliver transiently expressed recombinant antibodies for your individual needs, from smaller to large-scale projects.
CHO cells (Chinese Hamster Ovary cells) are used for transient recombinant antibody production because they offer a stable environment for protein expression, can produce complex proteins with proper folding and post-translational modifications, and are amenable to high-yield production.
Transient protein expression involves introducing foreign genes into cells for a short period, resulting in temporary protein production. Stable protein expression involves integrating genes into the cell’s genome for long-term and continuous protein production.
Transient recombinant antibodies are temporarily produced antibodies created by introducing foreign antibody genes into cells, allowing them to synthesize the antibody for a limited time, typically a few days to weeks.
Expression vectors for mammalian cells are specialized DNA molecules used to transfer and express foreign genes in mammalian cells, enabling the production of proteins or other molecules of interest. A frequently used vector technology is based on viral vectors.