Cellular research involves growing and studying cells outside a living organism in a process called cell culture. This requires placing cells into a favorable, artificial environment. To sustain them, this environment must include a nutrient-rich liquid, or medium, that provides the components for their survival and growth. The careful preparation of this culture medium is foundational for successful laboratory work.
What is DMEM?
DMEM, or Dulbecco’s Modified Eagle Medium, is a basal medium used extensively in cell culture laboratories. It was developed as an enriched version of Eagle’s Minimum Essential Medium (EMEM), containing a four-fold increase in amino acids and vitamins to support a wider variety of mammalian cells. This medium is well-suited for growing adherent cells that attach to a culture dish surface. As a “defined” medium, its chemical composition is precisely known, but it requires supplementation with products like fetal bovine serum (FBS) to create a complete growth environment.
The Role of Fisher Scientific in Supplying DMEM
Fisher Scientific, part of Thermo Fisher Scientific, is a major supplier of scientific products, including many formulations of DMEM. For scientific studies to be reproducible, the materials used must be reliable and uniform from batch to batch. Fisher Scientific addresses this need by implementing quality control tests on its media products. These tests check for sterility, correct pH levels, and the absence of contaminants, allowing laboratories to source the specific DMEM formulation required for their work with confidence.
Key Components and Formulations of DMEM
The effectiveness of DMEM stems from its balanced mixture of ingredients. The foundational components include amino acids for creating proteins, vitamins that act as coenzymes in cellular reactions, and inorganic salts to maintain the correct osmotic pressure. Glucose serves as the primary energy source for the cells, and DMEM has a higher glucose concentration than its predecessor, EMEM.
To maintain a stable pH, DMEM relies on a buffer system. Most formulations use sodium bicarbonate, which requires a controlled atmosphere with elevated carbon dioxide (CO2) levels, managed inside a CO2 incubator. Some versions include HEPES buffer for pH stability in environments without controlled CO2. Many formulations also contain phenol red, a pH indicator that changes color to provide a quick visual cue if the medium becomes too acidic or alkaline.
Scientists can choose from numerous DMEM formulations to match the specific needs of their experiments. This flexibility allows researchers to optimize the growth conditions for their particular cell line. Common variations include:
- Glucose levels, with “high glucose” (4.5 g/L) and “low glucose” (1.0 g/L) options available for cells with different metabolic rates.
- L-glutamine, an unstable amino acid. Some formulations are sold without it, requiring fresh addition, while others contain stable substitutes like GlutaMAX.
- Sodium pyruvate, which can be included as an additional energy source for certain cell types.
- Phenol red, which is removed from some formulations for experiments where the indicator might interfere, such as in fluorescence microscopy studies.
Applications of DMEM in Research
DMEM’s versatility has made it a standard medium in numerous fields of biological research. In basic cell biology, it is used to grow cells for studying fundamental processes like cell division, differentiation, and communication. Its defined composition provides a stable baseline for observing how cells behave and respond to various stimuli.
In virology, DMEM is used to culture host cells that are then infected with viruses, allowing researchers to study viral replication and infection mechanisms. The pharmaceutical industry uses it for drug discovery and toxicology studies. Potential new medicines are tested on cultured cells to screen for efficacy and assess toxic effects before moving to more complex testing models.
Cancer research also makes extensive use of DMEM for growing and maintaining a wide variety of cancer cell lines. These cell lines are used to study tumor biology, understand how cancer spreads, and test new anti-cancer therapies. The medium’s ability to support robust growth is suitable for producing the large quantities of cells needed for these experiments.