Fetal calf serum
Fetal or fetal calf serum (FCS) is obtained from the blood of cow fetuses and is a main component of many nutrient media that are needed for the rearing and cultivation of cells in cell culture . The term FKS is rarely used, however, the English terms fetal bovine serum (FBS), fetal calf serum (FCS) or newborn calf serum (NCS) are more common.
Areas of application
Part of nutrient media for cell culture
Fetal calf serum contains a wide variety of proteins, not all of which are known today. These proteins also include growth factors that are necessary for culturing cells in cell culture flasks.
Additive for cryopreservation (freezing)
If cells or sensitive proteins are to be frozen ( cryopreservation ), calf serum (1% to 20%) is usually added to protect the cells from frost damage. There are now also VCS-free alternatives.
Prevention of enzymatic reactions
In the handling of cell cultures, enzymes are often used; this typically includes trypsinizing the cells in order to detach them from the culture dish. After an exposure time, the further enzymatic reaction must be stopped; this is often done by adding fetal calf serum, as this contains protease inhibitors, in particular α-1-antitrypsin , but also offers the enzyme a large amount of alternative substrates .
FKS and GMP
The term Good Manufacturing Practice (GMP) (German Good Manufacturing Practice ) are purity / quality guidelines and summarized that must be adhered to in the preparation of a medicament. GMP guidelines must also be observed when producing cell cultures for therapeutic use (for example for tissue engineering or stem cell transplantation ). The use of calf serum is not possible under these conditions for many reasons. One reason is the large number of unknown proteins, which can lead to severe side effects and allergies in patients. Furthermore, calf serum can contain impurities and transmit diseases (e.g. through mycoplasma ). Efforts have therefore been underway for a number of years to replace fetal calf serum in the culture media with synthetic substances with defined properties.
"Serum-free" culture media are now also available, which are mainly used in cell therapy and regenerative medicine.
Manufacturing
The procedure for obtaining the substance consists of removing the uterus and the unborn fetus. The fetus is removed from the sheath and the cord is cut off. Then blood is taken from the fetus from the heart, which is used to obtain serum.
Replacement of FKS
Researchers at ETH Zurich have been working on the “Serum Free” project since 2005 to develop a replacement for VCS. The aim of the project is to significantly reduce the proportion of fetal calf serum in cell culture media. The substitute is a mixture of individual compounds , so it is "chemically fully defined" and therefore corresponds to the quality feature that a nutrient medium should be standardized. Contamination of the nutrient medium by mycoplasmas can also be prevented in this way. Another reason for the development is that cell cultures produced with FCS can hardly be registered as therapeutic cells. There is now a wide range of serum-free media for cultivating cell lines and stem cells .
Another alternative to fetal calf serum is human platelet lysate (HPL), which is obtained from platelet-rich blood plasma. In addition to preparation for research purposes, it is also available in GMP quality.
Controversy and criticism
The organization Doctors Against Tierversuche eV criticizes the use of fetal calf serum, for which around one to two million animals are killed every year. Other media such as human platelet lysate (hPL) or synthetically produced replacement sera are uncomplicated and inexpensive to produce. Since these media are made from human material, they are more suitable for the cultivation of human cells than fetal calf serum. The switch to nutrient media without fetal calf serum has not yet taken place because the cell cultures adapting to the new nutrient medium would result in growth losses that could cause short-term costs for the laboratories.
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- ↑ Rowley SD: Regulation of hematopoietic stem cell processing and transplantation. In: International Journal of Hematology . No. 75 , 2002, pp. 237-245 , PMID 11999350 .
- ^ Taupin P: Derivation of embryonic stem cells for cellular therapy: Challenges and new strategies . In: Med Sci Monit . No. 12 (4) , 2006, pp. RA75-78 , PMID 16572064 .
- ↑ Andrea Schrödel: The role of fetal calf serum in cell culture media . In Biologie in our Time , Volume 37, Number 5, October 2007, Page 289, ISSN 0045-205X doi : 10.1002 / biuz.200790079 (PDF; 138 kB)
- ↑ a b Christoph Meier: The “Serum Free” project - Less dirt in cell cultures. In: ETH Life website - know what's going on . April 5, 2005, accessed October 27, 2010 .
- ↑ Kathrin Burger: A cruel side effect. In: Website taz.de . February 18, 2005, accessed October 27, 2010 .
- ^ [1] Serum-free culturing of mammalian cells - Adaptation to and cryopreservation in fully defined media (PDF file).
- ↑ Food for cell cultures. Accessed November 20, 2017 (German).
- ↑ FCS-free - culture media without fetal calf serum. Accessed November 20, 2017 (German).
- ^ Opinion on fetal calf serum. Accessed November 20, 2017 (German).