Fetal Bovine Serum (FBS) is a commonly used supplement in eukaryotic cell culture for biological research, pharmaceutical development, and biomanufacturing. It supports the growth of many cell types outside their natural environment. Its unique composition allows for versatility across various cell culture applications.
Origin and Collection
Fetal Bovine Serum is derived from the blood of bovine fetuses, making it a byproduct of the meat industry. The collection process typically occurs in commercial slaughterhouses after the pregnant cow has been processed. The fetus is usually removed from the uterus, and blood is collected aseptically, often via cardiac puncture, into a sterile container or blood bag.
The blood is then allowed to clot, separating the cellular components from the clear, straw-colored serum. Industry standards emphasize ethical sourcing and careful collection to ensure quality and minimize contamination. Guidelines suggest the fetus should be unconscious at the time of collection, typically after a sufficient period following the mother’s slaughter.
Key Molecular Components
FBS is a complex biological fluid containing a diverse array of molecules that support cellular functions. Proteins constitute a large portion, including albumin, which maintains osmotic balance and transports molecules, and various globulins. Fibronectin and other transport proteins also facilitate the delivery of essential nutrients. The serum is rich in growth factors such as Platelet-Derived Growth Factor (PDGF), Epidermal Growth Factor (EGF), Fibroblast Growth Factor (FGF), Insulin-like Growth Factors (IGFs), and Transforming Growth Factor-beta (TGF-β). Hormones like insulin, thyroid hormones, prostaglandins, and various steroid hormones are also present. Additionally, FBS provides essential building blocks such as amino acids, vitamins (including B-complex and fat-soluble types), and lipids like fatty acids, cholesterol, and phospholipids. Carbohydrates, primarily glucose, serve as energy sources, while inorganic salts and trace elements like iron, zinc, and copper are vital for osmotic balance and enzymatic activity.
Functional Roles in Cell Culture
The diverse components within FBS contribute significantly to its effectiveness in supporting cell growth and maintenance in laboratory settings. Growth factors and hormones stimulate cell proliferation, differentiation, and survival. These molecules regulate cellular metabolism, providing signals for cell division and specialization. Transport proteins, including albumin, bind and deliver essential nutrients, hormones, and trace elements to cells.
FBS also provides a natural buffering capacity, helping to maintain stable pH levels in the culture medium, which is crucial for cell viability. Adhesion factors like fibronectin promote cell attachment to culture surfaces, a requirement for many cell types to grow properly. Protease inhibitors within the serum protect cells from enzymatic degradation.
Preparation and Quality Control
After collection, raw serum undergoes several processing steps before it is suitable for cell culture. The blood is allowed to clot and then centrifuged to remove cellular components and fibrin. Subsequently, the serum is subjected to sterile filtration, typically using a series of filters with a final pore size of 0.1 microns, to remove particulates and microbes.
Some FBS batches may undergo heat inactivation (e.g., 56°C for 30 minutes) to inactivate complement proteins that could interfere with certain immunological assays or sensitive cell lines. Extensive quality control testing is performed to ensure the product’s safety and consistency. This includes screening for viral contaminants such as Bovine Viral Diarrhea Virus (BVDV), Infectious Bovine Rhinotracheitis (IBR), and Parainfluenza-3 (PI3), as well as mycoplasma. Batch consistency and traceability are also monitored through regulatory standards.