Chemically defined medium
Encyclopedia
A chemically defined medium is a growth medium
suitable for the in vitro
cell culture
of human or animal cells in which all of the chemical components are known. The term chemically defined medium was defined by Jayme and Smith (2000) as a 'Basal formulation which may also be protein-free and is comprised solely of biochemically-defined low molecular weight constituents'.
A chemically defined medium is entirely free of animal-derived components and represents the purest and most consistent cell culture environment.
By definition chemically defined media cannot contain either fetal bovine serum
, bovine serum albumin
or human serum albumin
as these products are derived from bovine or human sources and contain complex mixes of albumins and lipids. The term chemically defined media is often misused in the literature to refer to serum albumin-containing media. Animal serum or albumin is routinely added to culture media as a source of nutrients and other ill-defined factors, despite technical disadvantages to its inclusion and its high cost. Technical disadvantages to using serum include the undefined nature of serum, batch-to-batch variability in composition, and the risk of contamination. There are increasing concerns about animal suffering inflicted during serum collection that add an ethical imperative to move away from the use of serum wherever possible.
Chemically defined media differ from serum-free media in that bovine serum albumin
or human serum albumin
with either a chemically defined recombinant version (which lacks the albumin associated lipids) or synthetic chemical such as the polymer polyvinyl alcohol
which can reproduce some of the functions of BSA/HSA. The next level of defined media, below chemically defined media is Protein-Free Media. These media contain animal protein hydrolysates and are complex to formulate although are commonly used for insect or CHO
cell culture. Animal culture media can be divided into five subsets based on the level of defined media (Jayme and Smith, 2000): From lowest definition to highest these are: 1, Serum-containing media; 2, Reduced-serum media; 3, Serum-free media, 4, Protein-free media; 5, Chemically-defined media.
The term 'defined media' is commonly used to refer to serum-free media. Media formulations containing the media supplement B27 (supplied by Invitrogen
) are often erroneously referred to as chemically defined media (e.g. Yao et al., 2006) despite this product containing bovine serum albumin (Chen et al., 2008) using the above definitions this type of media is referred to as serum-free media.
Serum-free media are commonly supplemented with bovine or human serum albumin, insulin
, transferrin
, selenium
and a thiol
such as 2-mercaptoethanol
or 1-thioglycerol
Other variants of serum-free media include:
Animal protein-free media, containing human serum albumin, human transferrin, human insulin, but animal-derived lipids (as with StemPro 34).
Xeno-free media, containing human serum albumin, human transferrin, human insulin, and chemically defined or human lipids.
Recombinant, xeno-free media, containing recombinant
human serum albumin or a synthetic replacement, recombinant human insulin, recombinant human transferrin, and chemically defined lipids.
Growth medium
A growth medium or culture medium is a liquid or gel designed to support the growth of microorganisms or cells, or small plants like the moss Physcomitrella patens.There are different types of media for growing different types of cells....
suitable for the in vitro
In vitro
In vitro refers to studies in experimental biology that are conducted using components of an organism that have been isolated from their usual biological context in order to permit a more detailed or more convenient analysis than can be done with whole organisms. Colloquially, these experiments...
cell culture
Cell culture
Cell culture is the complex process by which cells are grown under controlled conditions. In practice, the term "cell culture" has come to refer to the culturing of cells derived from singlecellular eukaryotes, especially animal cells. However, there are also cultures of plants, fungi and microbes,...
of human or animal cells in which all of the chemical components are known. The term chemically defined medium was defined by Jayme and Smith (2000) as a 'Basal formulation which may also be protein-free and is comprised solely of biochemically-defined low molecular weight constituents'.
A chemically defined medium is entirely free of animal-derived components and represents the purest and most consistent cell culture environment.
By definition chemically defined media cannot contain either fetal bovine serum
Fetal bovine serum
Fetal bovine serum or FBS is the portion of plasma remaining after coagulation of blood, during which process the plasma protein fibrinogen is converted to fibrin and remains behind in the clot. Fetal bovine serum comes from the blood drawn from a bovine fetus via a closed system of collection at...
, bovine serum albumin
Bovine serum albumin
Bovine serum albumin is a serum albumin protein derived from cows. It is often used as a protein concentration standard....
or human serum albumin
Human serum albumin
Human serum albumin is the most abundant protein in human blood plasma. It is produced in the liver. Albumin constitutes about half of the blood serum protein...
as these products are derived from bovine or human sources and contain complex mixes of albumins and lipids. The term chemically defined media is often misused in the literature to refer to serum albumin-containing media. Animal serum or albumin is routinely added to culture media as a source of nutrients and other ill-defined factors, despite technical disadvantages to its inclusion and its high cost. Technical disadvantages to using serum include the undefined nature of serum, batch-to-batch variability in composition, and the risk of contamination. There are increasing concerns about animal suffering inflicted during serum collection that add an ethical imperative to move away from the use of serum wherever possible.
Chemically defined media differ from serum-free media in that bovine serum albumin
Bovine serum albumin
Bovine serum albumin is a serum albumin protein derived from cows. It is often used as a protein concentration standard....
or human serum albumin
Human serum albumin
Human serum albumin is the most abundant protein in human blood plasma. It is produced in the liver. Albumin constitutes about half of the blood serum protein...
with either a chemically defined recombinant version (which lacks the albumin associated lipids) or synthetic chemical such as the polymer polyvinyl alcohol
Polyvinyl alcohol
Polyvinyl alcohol is a water-soluble synthetic polymer .-Properties:...
which can reproduce some of the functions of BSA/HSA. The next level of defined media, below chemically defined media is Protein-Free Media. These media contain animal protein hydrolysates and are complex to formulate although are commonly used for insect or CHO
Chinese Hamster Ovary cell
Chinese hamster ovary cells are a cell line derived from the ovary of the Chinese hamster. They are often used in biological and medical research and commercially in the production of therapeutic proteins. They were introduced in the 1960s and grow as a cultured monolayer...
cell culture. Animal culture media can be divided into five subsets based on the level of defined media (Jayme and Smith, 2000): From lowest definition to highest these are: 1, Serum-containing media; 2, Reduced-serum media; 3, Serum-free media, 4, Protein-free media; 5, Chemically-defined media.
The term 'defined media' is commonly used to refer to serum-free media. Media formulations containing the media supplement B27 (supplied by Invitrogen
Invitrogen
Invitrogen Corporation was a large, multinational biotechnology company headquartered in Carlsbad, California. In November 2008, a merger between Applied Biosystems and Invitrogen was finalized...
) are often erroneously referred to as chemically defined media (e.g. Yao et al., 2006) despite this product containing bovine serum albumin (Chen et al., 2008) using the above definitions this type of media is referred to as serum-free media.
Serum-free media are commonly supplemented with bovine or human serum albumin, insulin
Insulin
Insulin is a hormone central to regulating carbohydrate and fat metabolism in the body. Insulin causes cells in the liver, muscle, and fat tissue to take up glucose from the blood, storing it as glycogen in the liver and muscle....
, transferrin
Transferrin
Transferrins are iron-binding blood plasma glycoproteins that control the level of free iron in biological fluids. In humans, it is encoded by the TF gene.Transferrin is a glycoprotein that binds iron very tightly but reversibly...
, selenium
Selenium
Selenium is a chemical element with atomic number 34, chemical symbol Se, and an atomic mass of 78.96. It is a nonmetal, whose properties are intermediate between those of adjacent chalcogen elements sulfur and tellurium...
and a thiol
Thiol
In organic chemistry, a thiol is an organosulfur compound that contains a carbon-bonded sulfhydryl group...
such as 2-mercaptoethanol
2-Mercaptoethanol
2-Mercaptoethanol is the chemical compound with the formula HOCH2CH2SH. It is a hybrid of ethylene glycol, HOCH2CH2OH, and 1,2-ethanedithiol, HSCH2CH2SH...
or 1-thioglycerol
Other variants of serum-free media include:
Animal protein-free media, containing human serum albumin, human transferrin, human insulin, but animal-derived lipids (as with StemPro 34).
Xeno-free media, containing human serum albumin, human transferrin, human insulin, and chemically defined or human lipids.
Recombinant, xeno-free media, containing recombinant
Recombinant DNA
Recombinant DNA molecules are DNA sequences that result from the use of laboratory methods to bring together genetic material from multiple sources, creating sequences that would not otherwise be found in biological organisms...
human serum albumin or a synthetic replacement, recombinant human insulin, recombinant human transferrin, and chemically defined lipids.
See also
- Biological immortalityBiological immortalityBiological immortality refers to a stable rate of mortality as a function of chronological age. Some individual cells and entire organisms in some species achieve this state either throughout their existence or after living long enough. This requires that death occur from injury or disease rather...
- Cell culture assaysCell culture assaysIn Biomaterials Testing, a cell culture assay is any method which is used to assess the cytotoxicity of a material. This refers to the in vitro assessment of material to determine whether it releases toxic chemicals in sufficient quantities to kill cells either directly or indirectly through the...
- Organ cultureOrgan cultureOrgan culture is a development from tissue culture methods of research, the organ culture is able to accurately model functions of an organ in various states and conditions by the use of the actual in vitro organ itself....
- Plant tissue culturePlant tissue culturePlant tissue culture is a collection of techniques used to maintain or grow plant cells, tissues or organs under sterile conditions on a nutrient culture medium of known composition. Plant tissue culture is widely used to produce clones of a plant in a method known as micropropagation...
- Tissue cultureTissue cultureTissue culture is the growth of tissues or cells separate from the organism. This is typically facilitated via use of a liquid, semi-solid, or solid growth medium, such as broth or agar...