Fetal bovine serum

Fetal bovine serum (FBS) is the most widely used serum-supplement for the in vitro cell culture of eukaryotic cells. It is commonly utilized in biomedical research, pharmaceutical development, and biomanufacturing due to its ability to support a wide variety of cell types. This is due to it having a very low level of antibodies and containing more growth factors, allowing for versatility in many cell culture applications. Fetal bovine serum is derived from the blood drawn from a bovine fetus via a closed system of collection at the slaughterhouse.

The globular protein bovine serum albumin (BSA) is a major component of fetal bovine serum. It plays a crucial role in maintaining osmotic balance and transporting molecules within the culture medium. Besides BSA, fetal bovine serum is a rich source of growth and attachment factors, lipids, hormones, nutrients and electrolytes necessary to support cell growth in culture. It is typically added to basal cell culture medium, such as DMEM or RPMI, at a 5–10% concentration.

Because it is a biological product, FBS is not a fully defined media component, and as such varies in composition between batches. As a result of this and in an attempt to minimize the possibility of transfer of adventitious agents, serum-free and chemically defined media (CDM) have been developed. However, the effectiveness of serum-free media is limited as many cell lines still require serum in order to grow, and many serum-free media formulations can only support the growth of narrowly-defined types of cells.