What are the most costly ingredients in today’s CD media for GMP protein production (mammalian) that make them so expensive (~US$100/L)?

Answer

It not the cost of the ingredients that dictate the product cost but the labor involved. A few of the ingredients in a CD formulation are costly (i.e. monothioglycerol) but the concentrations in the 1X formula are so low as to not be a significant factor. A CD medium is a very complicated medium because it must allow for as good or better growth in the absence of proteins and peptides as obtained in a medium supplemented with serum or serum proteins. A typical CD medium will contain everything found in a standard basal medium formulation plus about 25 or more trace elements. Because the concentration of the trace elements is too low to weigh out, stock conntrates (often about 20,000X) must be made. An inorganic substitute for transferrin is also needed as well as inorganic components to reduce apoptosis and free radical production. Each component must be put into solution at the right pH and added to the water in the proper order as to maintain the cells in solution.