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The culture medium is the most important component of the culture environment, because it provides the necessary nutrients, growth factors, and hormones for cell growth, as well as regulating the pH and the osmotic pressure of the culture.

Although initial cell culture experiments were performed using natural media obtained from tissue extracts and body fluids, the need for standardization, media quality, and increased demand led to the development of defined media. The three basic classes of media are basal media, reduced-serum media, and serum-free media, which differ in their requirement for supplementation with serum.

Serum



Serum is vitally important as a source of growth and adhesion factors, hormones, lipids and minerals for the culture of cells in basal media.  In addition, serum also regulates cell membrane permeability and serves as a carrier for lipids, enzymes, micronutrients, and trace elements into the cell.  However, using serum in media has a number of disadvantages including high cost, problems with standardization, specificity, variability, and unwanted effects such as stimulation or inhibition of growth and/or cellular function on certain cell cultures.  If the serum is not obtained from reputable source, contamination can also pose a serious threat to successful cell culture experiments.   To address this threat, all Invitrogen and GIBCO® products, including sera, are tested for contamination and guaranteed for their quality, safety, consistency, and regulatory compliance.

Basal Media

The majority of cell lines grow well in basal media, which contain amino acids, vitamins, inorganic salts, and a carbon source such as glucose, but these basal media formulations must be further supplemented with serum.

 

Reduced-Serum Media

Another strategy to reduce the undesired effects of serum in cell culture experiments is to use reduced-serum media. Reduced-serum media are basal media formulations enriched with nutrients and animal-derived factors, which reduce the amount of serum that is needed.

Serum-Free Media

Serum-free media (SFM) circumvents issues with using animal sera by replacing the serum with appropriate nutritional and hormonal formulations. Serum-free media formulations exist for many primary cultures and cell lines, including recombinant protein producing lines of Chinese Hamster Ovary (CHO), various hybridoma cell lines, the insect lines Sf9 and Sf21 (Spodoptera frugiperda), and for cell lines that act as hosts for viral production (e.g., 293, VERO, MDCK, MDBK), and others. One of the major advantages of using serum-free media is the ability to make the medium selective for specific cell types by choosing the appropriate combination of growth factors. The table below lists the advantages and disadvantages of serum-free media.


Advantages
Disadvantages
  • Increased definition
  • Requirement for cell type-specific media formulations
  • More consistent performance
  • Need for higher degree of reagent purity
  • Easier purification and downstream processing
  • Slower growth
  • Precise evaluation of cellular functions

  • Increased productivity

  • Better control over physiological response

  • Enhanced detection of cellular mediators