The globular protein, bovine serum albumin (BSA), is a major component of fetal bovine serum. The rich variety of proteins in fetal bovine serum maintains cultured cells in a medium in which they can survive, grow, and divide. However, the presence of the many proteins in fetal bovine serum can also mean that purification of secreted proteins from the cells can be a more laborious process due to having to remove the contaminating proteins during the purification process.
Fetal bovine serum is commercially available from many manufacturers, and because the cells are highly sensitive, it may be wise to take time to adapt the cells when changing fetal bovine serum from different manufacturers, such as by mixing 50% of the old serum with 50% of the new serum, and leaving the cells in that environment for a while.
Fetal bovine serum should be stored frozen before adding to media in order to prevent contamination. When thawing fetal bovine serum, even though it will take longer, it should be warmed at room temperature and not in a 37-degree water bath. When performing cell culture, the bottle of fetal bovine serum should be opened and closed in a biosafety cell culture hood, and in-person training should be obtained on how to perform sterile manipulations.