Fetal Bovine Serum (FBS) is a widely used supplement in cell culture, supporting the growth of various cell types in a laboratory setting. It provides a rich mixture of growth factors, proteins, hormones, and nutrients. FBS is crucial for cultivating cells used in developing pharmaceuticals, vaccines, and in biomedical research.
Origin of Fetal Bovine Serum
Fetal Bovine Serum originates from the blood of bovine fetuses, obtained from pregnant cows slaughtered for meat production. The cattle industry is the primary source, making FBS a byproduct of meat processing.
FBS collection occurs at commercial slaughterhouses. While not every slaughtered cow is pregnant, an estimated 8% may be, making slaughterhouses a consistent source for FBS production.
The Collection Process
Blood collection from the bovine fetus is a precise procedure, typically performed immediately after the pregnant cow is slaughtered. Cardiac puncture, inserting a needle directly into the fetal heart, is the primary method. This technique maximizes blood volume and minimizes microbial contamination from the surrounding environment or the fetus itself.
The procedure occurs while the fetus is still within the uterus or shortly after its removal, known as in utero collection. A closed system maintains sterility and prevents air exposure, which helps regulate endotoxin and hemoglobin levels. After collection, the blood is promptly refrigerated to encourage clotting before further processing.
Processing After Collection
After collection, the blood undergoes several processing steps to transform it into usable serum. First, the blood clots naturally, separating cellular components from the liquid serum, yielding a clear, straw-colored liquid.
Next, centrifugation further separates remaining blood cells, coagulation fibrinogens, and low-solubility proteins from the serum, resulting in a cleaner product. The raw serum is then often frozen for transport to specialized processing facilities.
At the processing facility, the serum is thawed and undergoes a series of filtration steps. This typically involves passing it through progressively finer filters, often culminating in triple sterile 0.1 micrometer membrane filters, to remove microorganisms and ensure sterility. After filtration, batches are often pooled and homogenized to ensure consistency before being bottled and stringent quality control testing.
Ethical Considerations and Alternatives
The collection of Fetal Bovine Serum raises significant ethical concerns, primarily regarding animal welfare. A key debate point is the potential for fetal pain and consciousness during cardiac puncture, as guidelines suggest the fetus should be unconscious, yet a heartbeat may still be present. Organizations and regulations aim to ensure humane slaughter of pregnant animals and that fetuses are unconscious before blood collection.
Due to these ethical considerations, batch-to-batch variability, and potential for contamination, researchers are actively pursuing alternatives to FBS. Serum-free media are chemically defined formulations without animal serum, offering a more consistent and controlled environment for cell growth. Human platelet lysate (hPL), derived from human blood platelets, is another promising alternative, providing growth factors suitable for culturing human cells and considered more physiologically relevant and safer for clinical applications. While a universal alternative for all cell types remains a challenge, these developments reflect a growing effort to reduce reliance on FBS in scientific research.