Quality Assessment and Application Key Points of Fetal Bovine Serum in Cell Culture

Why Fetal Bovine Serum Has Become an Important Additive for Cell Culture

Fetal bovine serum is derived from fetal bovine blood and is produced through processes such as collection, separation, and filtration. Its composition is relatively complex, including proteins, growth factors, hormones, lipids, trace elements, and vitamins, and it can provide attachment factors, nutritional support, and antioxidant protection for various mammalian cells. In basal media, the common supplementation ratio of fetal bovine serum is generally between 5% and 20%, but the specific ratio should be adjusted according to cell type, culture system, and experimental purpose.

Key Quality Indicators Affecting Result Reproducibility

Fetal bovine serum from different origins and different lots may differ in total protein content, endotoxin levels, hemoglobin concentration, and microbial load. Laboratories usually focus on whether it has undergone sterile filtration and whether it has been tested for mycoplasma, bacteria, fungi, and other indicators. Generally, endotoxin is required to be at a low level, and particular attention is needed for sensitive cells such as dendritic cells and macrophages. In appearance, serum should generally be a clear, slightly yellow to orange-yellow liquid with no obvious suspended particles. If a large amount of precipitate or abnormal color appears, it is advisable to use it with caution.

Endotoxin: affects immune cell activity and inflammatory responses, and should be a routine risk assessment item.

Hemoglobin: can help assess control of the raw material collection process, and is not a single decisive indicator.

Microbial testing: includes bacteria, fungi, mycoplasma, etc., and supplier lot reports need to be reviewed.

Recommendations for Use to Reduce Lot-to-Lot Variation

Before selecting fetal bovine serum, laboratories may request trial samples for cell proliferation, morphology, and function testing. For critical cell lines, it is recommended to compare the performance of different lots under the same culture conditions. If changing lots, parallel experiments should be arranged, and passage time, confluence, and viability changes should be recorded. If long-term continuous culture is required for the same project, reserve inventory from the same lot as much as possible to reduce variables. In daily use, avoid repeated freeze-thaw cycles, and aliquot for single use; thawing should preferably be performed slowly at 2°C to 8°C, and after thawing, mix gently.

Establish a Stable Serum Management Workflow

The quality stability of fetal bovine serum depends not only on the supply side but is also closely related to laboratory management. A record system for receipt, storage, opening, and use should be established, and lot number information should be reviewed regularly. When selecting qualified suppliers, one should not only look at promotional language, but also pay more attention to the completeness of quality documents, cold-chain transportation records, and after-sales technical support. Gradually forming a traceable and verifiable serum management workflow helps improve the reproducibility of cell culture results.