Fetal bovine serum (FBS) is clotted whole fetal blood that has been centrifuged to remove still-present blood cells and used to supplement cell growth in culture media.
While other animal sera exist, FBS is the most common for research with cells due to its abundance of growth factors, which is ideal for propagating cell proliferation.
The process of fetal bovine serum collection begins at abattoirs, otherwise known as slaughterhouses. As a byproduct of harvesting cattle for the meatpacking industry, FBS can only be drawn in licensed facilities and in aseptic conditions that meet federal regulations to ensure safety and quality.
Read on to learn more about fetal bovine serum collection, from the step by step process to industry regulations.
Why fetal bovine serum?
So, what is fetal bovine serum and why is it important? FBS is popular among various industries seeking in vitro cell, tissue, and organ culture because it’s a vital source of:
- Attachment factors
- Growth factors
- Spreading factors
- Transport proteins
Moreover, fetal bovine blood has lower levels of gamma globulin, higher levels of growth factors, and fewer complement proteins than the alternatives (e.g., newborn, calf, adult, or donor bovine serum).1
Who regulates FBS collection?
Government agencies (DEFRA, USDA, MPI, DAWR, etc.) set standards for the animal sera industry’s requirements and regulations for import and export of animal by-products.
In addition to government agencies, the International Serum Industry Association (ISIA) is focused on four key areas: Standardization, Education, Regulatory, and Traceability for the global serum industry.
As a form of risk mitigation, the ISIA Traceability Program:2
- Requires an independent third-party audit
- Covers identification and tracking of the product throughout every step of the process
- Grants certification based on the approved third-party audit
- Requires recertification every three years
Through this, animal-derived materials pose a much more diminished risk to the medical, science, and research industries that rely on them.3
The general procedure for FBS collection includes the following phases:
- As a byproduct of the meatpacking industry, fetal blood is collected at the time of harvest from abattoirs where cows pass both veterinary pre- and post-mortem inspections
- Fetal bovine blood is collected from deceased pregnant cows in government approved facilities
- Blood is drawn via cardiac puncture from the expired fetus in a closed, aseptic system using best practices to regulate hemoglobin and endotoxin levels
- The blood is refrigerated to encourage clotting
- Blood is then processed into raw serum
Chris Scanlon, Market Development Manager within the FBS program, explains Thermo Fisher Scientific’s dedication to quality starting at the collection process. Being vertically integrated, Thermo Fisher Scientific has full oversight of the FBS collection process in most countries. Whereas other companies often utilize a third party for the initial steps of the collection process, Thermo Fisher Scientific prioritizes having this oversight from “farm to bench.”
Following collection, the fetal blood is given time to clot before centrifugation. The remaining fluid from the clotted blood is now fetal bovine serum.
How much serum is produced?
The age and size of the bovine fetus determine the amount of FBS that can be produced.
- A 3-month-old fetus yields approximately 150 mL of raw FBS
- A 6-month-old fetus yields approximately 350 mL of raw FBS
- A 9-month old-fetus yields approximately 550 mL of raw FBS
Approximately 500,000 L of FBS are produced annually, requiring the harvest of about a million bovine fetuses.4
How is FBS stored?
The best way to prevent degradation of serum quality, once collected and processed, is to store it and transport it in controlled conditions. FBS should be:
- Frozen between ≤-10
- Thawed between 2 to 8°C.
Given the ability of serum to be stored for extended periods of time, researchers and manufacturers will often use the same serum over the timespan of a couple years. However, since FBS is the only reagent in cell culture that is undefined, when it comes time to replenish their product, they desire one from a similar lot with the same kind of specs as the product purchased two years ago. Thermo Fisher Scientific is committed to providing solutions that help ensure consistency from lot to lot. Through various technologies such as FBS fingerprinting and the iMATCH Sera Lot Tool, we instill confidence in the reproducibility that researchers want each and every time in their cell culture.
When it comes to what fetal bovine serum does, it’s important to understand how it functions in studies and research. Methodology and conditions are carefully monitored not only for the collection but also for the processing, storage, and treatment of FBS to diminish the risk of contamination. The level of caution also increases according to the intended use of the serum. Particularly when animal sera are intended for use in pharmaceutical production, testing and requirements become more rigorous. Robust Quality Management Systems (QMS) and following current Good Manufacturing Practices (cGMP) are required to meet the serum industry standards.
Any medicinal merchandise manufacturing must observe Good Manufacturing Practices (GMPs). GMP is an elaborate system of stipulations that exist to promote products of the highest quality, especially concentrated on raw materials like FBS.
With regulations such as GMP and those established by the FDA considered standard across the industry, it’s common for FBS customers to assume that all products are of the same quality. However, Judy Pogoda-Leone, Senior Manager, Technical Affairs of Global Sera at Thermo Fisher Scientific, explains that there are a couple key factors that customers should always make sure to monitor closely when selecting products.
Judy notes the first important factor is the sterility of the product. “Many take for granted that it’s been filtered, but it’s still important that customers take the precautions to make sure their product is sterile and filtered.” Closely related, the second factor to keep an eye on is mycoplasma. Although this is often not discussed because it’s somewhat of a “voodoo” subject given the fact that mycoplasma contamination has the ability to ruin everything in the lab,that makes it all the more important to prioritize. Committed to high standards in product quality, Thermo Fisher Scientific uses USP & EP testing in order to meet the US and European requirements for sterility and mycoplasma.
In describing the efforts of Thermo Fisher Scientific to meet these standards, Judy adds, “We’ve taken the extra step to make sure that our customers—in Europe specifically—who are purchasing product for drug manufacturing or vaccine manufacturing, get the product that meets these requirements needed for their work.”
The future of fetal bovine serum
Since FBS is a by-product of harvesting cattle for the meatpacking industry, the supply of FBS can fluctuate. The added variables of the environment and geopolitical events account for a somewhat inconsistent supply continuity and price stability.
While the search for a serum-free medium with the same growth-promoting capabilities is ongoing, FBS remains the preferred source for cell culture applications and will continue to be the growth medium in the foreseeable future.
- Fang, C. Y., Wu, C. C., Fang, C. L., Chen, W. Y., & Chen, C. L. (2017). Long-term growth comparison studies of FBS and FBS alternatives in six head and neck cell lines. PloS one, 12(6), e0178960. doi:10.1371/journal.pone.0178960
- C. E. A. Jochems, J. B.F. van der Valk, F. R. Stafleu, V. Baumans. The use of fetal bovine serum: ethical or scientific problem? ATLA 30, 219-227.
For Research Use or Further Manufacturing Use only. Serum and blood proteins are not for direct administration into humans or animals.