Chemically defined serum replacement – specifically for high cell density culture

CDM-HD Serum Replacement is designed for use in 2-compartment high density mammalian culture systems where cell densities exceed 1E+7 cells/ml. Under these conditions cell-secreted conditioning factors play a significant role in supporting the culture. Serum can therefore usually be completely replaced with CDM-HD. This simplified media is a mix of low molecular weight compounds that is chemically defined and consistent lot-to-lot as well as being very economical.

CDM-HD Serum replacement powder enables the cost, risks and lot-testing associated with serum to be eliminated. In the FiberCell bioreactor most types of cells require no adaptation period when switching over from serum to CDM-HD. Media produced using CDM-HD is protein-free and so greatly facilitates the purification of mAbs. Also, it is ideal for EV / exosome production with HEK293 and many other types of cells. It is a cGMP compliant product.

Problems with using serum

Because of undefined composition, risk of contaminations, cost factors and also animal welfare considerations, the switch to serum free alternatives is promoted by regulatory authorities, industry and academics in general. Serum is an ill-defined mixture and often contains adventitious agents and by-products like bacterial endotoxins and other immunogenic contaminants. Furthermore batch qualities vary and the costs can be high. Sera are a major source of viral contaminants which often do not produce cytopathic effects or morphological changes but once present are almost impossible to remove from cultures.

Some important advantages in the use of totally defined media are the avoidance of risks of contamination and immunogenic stimuli and lot to lot consistency Possible contaminants include viruses, prions and mycoplasma which highly impair pharmacologic use of culture derived products. By contrast, a totally defined, animal component free, protein free medium will not contain any proteins nor any materials derived from animals. Purification of the desired secreted product is facilitated and regulatory compliance is made much simpler.

Example uses of CDM-HD serum replacement

Single step switch to serum free conditions

It takes a few days for the contaminating serum proteins to be cleared once the switch to CDM-HD has been made. Afterwards the target protein is usually the dominant protein in the unpurified supernatant.

CDM-HD serum replacement

Data courtesy of: Dr. Erin Bromage c/o the
US Veterinary Immune Reagents Network

MAb harvesting – 2 different MAbs

Secreted products such as monoclonal antibodies and recombinant proteins are free of contaminating proteins from the medium and can be purified using simplified protocols, increasing net yield in many cases.


Antibody from the FiberCell HFBR was very clean and properly folded.

Lane 1: control (3 ug)
Lanes 2, 3 and 4: unpurified harvests from the cartridge on day 7, 9 and 12 (DMEM and 10% CDM-HD) (2µl)
Lane 5: 10X conc. supernatant from a T-flask (using DMEM and 10% CDM-HD) (2µl)
Lane 6: T flask (using DMEM and 10% serum) (2µl)

Concentration of supernatant from HFBR:  2.5 mg/ml.

Data courtesy of Liying Lu, University of Massachusetts, Worcester, Worcester, Massachusetts.

What are the components of CDM-HD serum replacement?

Components of CDM-HD:CDM-HD does not contain:
Customized ratios of amino acids and metabolitesProtein
Vitamins and co-factorsHydrolysates
Trace elementsUndefined reagents
Micro-nutrientsAnimal-derived components
Extra buffering capacitySteroid hormones or peptide mitogens
Recombinant growth factorsPhenol red
Carbohydrates, including 1 gram of glucose/LPlurionic Detergent
All low molecular weight components, nothing larger than 3 kdHigh molecular weight materials including synthetic polymers

CDM-HD is produced under GMP conditions


Large-scale preparation of extracellular vesicles enriched with specific micro-RNA: Yoo, KW et al. ; Tissue Engineering. 2018 [abstract]

Efficient production and enhanced tumor delivery of engineered extracellular vesicles: Watson DC et al.; Biomaterials 105, 2016: 195-205 [Open Access]

Efficient production and purification of recombinant human interleukin-12 (IL-12) overexpressed in mammalian cells without affinity tag: Jayanthi S. et al.; Protein Expr Purif. 2014 Oct; 102: 76–84. [Open Access]

Take full advantage of high cell density mammalian cell culture and avoid using serum

The inconvenience of serum-containing media and the high cost of specialty medias can be avoided by employing CDM-HD Serum Replacement in high density culture systems.

Have a question?

Download the FiberCell product sheet and instructions for use or email us at