Fetal Bovine Serum, or FBS, is a supplement derived from the blood of bovine fetuses. It is the liquid component of blood that remains after coagulation removes cells and clotting factors. This serum is broadly used in biological research and biotechnology as an additive to cell culture medium. The primary function of this mixture is to support the growth and maintenance of eukaryotic cells in a laboratory setting.
The widespread use of FBS is due to its rich composition, which allows for the cultivation of many cell types outside their natural environment. Many life science companies are major suppliers of FBS, with one of the most recognized being Sigma-Aldrich, which now operates as MilliporeSigma.
The Crucial Role of FBS in Scientific Research
Fetal Bovine Serum supports robust cellular activity by promoting cell proliferation, or cell division. The serum ensures cell viability by delivering nutrients and protective factors. FBS also contains attachment factors that help many cell types adhere to the surface of the culture vessel, a requirement for their growth and survival.
In vaccine production, FBS nourishes the cells used to grow large quantities of viruses needed to create vaccines. The development of biopharmaceuticals, such as monoclonal antibodies for treating diseases like cancer and autoimmune disorders, also relies on cell cultures supplemented with FBS.
FBS is also used in fundamental research. Cancer researchers use it to grow cancer cell lines to study disease mechanisms and test potential new drugs. Stem cell research frequently employs FBS to maintain stem cell populations or to guide their development into specific cell types. Basic studies into cellular processes, from gene function to metabolic pathways, depend on the consistent cell growth that FBS provides.
Understanding FBS Sourcing and Key Components
Fetal Bovine Serum is a byproduct of the commercial meat industry, collected from the blood of bovine fetuses after the pregnant cow has been slaughtered. The collection is performed aseptically to prevent microbial contamination. Blood is drawn from the fetus, allowed to clot, and the serum is separated from the clotted blood cells through centrifugation.
The effectiveness of FBS for cell culture comes from its complex mixture of biomolecules. A prominent category is growth factors, which are proteins that stimulate cell division and differentiation. The serum also contains a variety of hormones that regulate cellular metabolism.
Transport proteins like albumin and transferrin are abundant; albumin helps maintain osmotic pressure, while transferrin carries iron to the cells. To help cells attach to the culture surface, FBS provides attachment factors like fibronectin. This rich, undefined composition explains its broad utility and the inherent biological variability between production batches.
Fetal Bovine Serum from Sigma-Aldrich: Quality and Product Lines
Given that FBS is a biological product with inherent variability, suppliers like Sigma-Aldrich prioritize rigorous quality control. Companies perform a battery of tests on each batch to ensure safety, purity, and performance. These tests confirm the serum is sterile and free from contaminants like bacteria, fungi, and mycoplasma.
Quality control assays also measure levels of endotoxins and hemoglobin. Suppliers conduct growth promotion assays using specific cell lines to verify that a batch effectively supports cell proliferation. This testing ensures the product meets specific standards, and researchers receive a Certificate of Analysis documenting these results for each lot.
To meet diverse experimental needs, suppliers offer several types of FBS. Standard FBS is for general cell culture, while specialized versions are available for sensitive applications. These variations include:
- Heat-inactivated FBS, which is treated to destroy complement proteins.
- Charcoal-stripped FBS, which has hormones removed for specific studies.
- Dialyzed FBS, which has small molecules removed.
- Gamma-irradiated FBS for viral inactivation.
The geographical origin of the serum is also specified for regulatory compliance and traceability.
Addressing Ethical Concerns and Exploring Alternatives
The use of Fetal Bovine Serum in research involves ethical and scientific considerations. The primary ethical issue centers on animal welfare regarding the collection process from bovine fetuses. The method of blood collection, often a cardiac puncture performed without anesthesia, has raised questions about the potential for fetal pain and distress.
From a scientific standpoint, FBS presents challenges due to its undefined composition and batch-to-batch variability, which can affect experimental reproducibility. There is also a risk of contamination with unknown viruses or prions. These issues have driven the search for alternatives, guided by the “3Rs” principle: Replacement, Reduction, and Refinement of animal-derived products in research.
Progress has been made in developing alternatives to FBS. These include serum-free media (SFM) and chemically defined media (CDM), where the exact chemical composition is known, eliminating batch variability. For research involving human cells, xeno-free media and human-derived supplements like human platelet lysate (HPL) are becoming more common.
While the complete replacement of FBS remains a challenge for some cell types, the ongoing development of these alternatives reflects a move towards more defined and ethically sourced materials in cell culture.