The technical disadvantages to using serum include its undefined nature, batch-to-batch variability in composition, and the risk of contamination.
These undefined animal-derived products will contain complex contaminants, such as the lipid content of albumin.
In contrast, chemically defined media require that all of the components must be identified and have their exact concentrations known.
To achieve this, chemically defined media is commonly supplemented with recombinant versions of albumin and growth factors, usually derived from rice or E. coli, or synthetic chemical such as the polymer polyvinyl alcohol which can reproduce some of the functions of BSA/HSA.
The constituents of a chemically defined media include: a basal media (such as DMEM, F12, or RPMI 1640, containing amino acids, vitamins, inorganic salts, buffers, antioxidants and energy sources), which is supplemented with recombinant albumin, chemically defined lipids, recombinant insulin and/or zinc, recombinant transferrin or iron, selenium and an antioxidant thiol such as 2-mercaptoethanol or 1-thioglycerol.
Chemically defined media that are designed for the cultivation of cells in suspension additionally contain suitable surfactants such as poloxamers in order to reduce shear stress caused by shaking and stirring.
Chemically defined media also allows researchers who are studying in the field of cell physiology (especially extracellular) and or molecule–cell interactions to eliminate any variables that may arise due to the effects of unknown components in the medium.
Peptide-free, protein-free, chemically defined media are rarely successfully formulated except for CHO and insect cells.
"Long-term self-renewal and directed differentiation of human embryonic stem cells in chemically defined conditions".
"Chemically defined media and the culture of mammalian preimplantation embryos: historical perspective and current issues".