Gibco DMEM High Glucose is a widely used liquid growth medium for culturing mammalian cells in laboratories. It is a modification of Eagle’s Minimal Essential Medium (MEM), providing a robust nutritional environment for cell proliferation. Its distinguishing feature is an elevated glucose concentration, a primary energy source for cell metabolism, making it well-suited for many cell culture applications.
Core Composition of High Glucose DMEM
High glucose DMEM contains 4.5 grams per liter (4500 mg/L) of D-glucose. This is a notable increase compared to low-glucose formulations (1.0 g/L), highlighting its energy-rich nature. Beyond glucose, the medium contains higher concentrations of amino acids and vitamins than the original MEM, supporting cellular processes. Inorganic salts maintain proper osmotic pressure and provide ions necessary for cellular function.
Many DMEM formulations incorporate phenol red, a pH indicator. This allows researchers to visually monitor the medium’s pH. The medium appears red at physiological pH (around 7.4), indicating healthy conditions. A color change to orange or yellow suggests increasing acidity (often due to metabolic byproducts), while pink or purple indicates alkalinity. This visual cue helps identify potential issues.
Common Formulations and Additives
L-glutamine is a common DMEM additive, serving as an important energy source and building block for proteins and nucleotides. However, L-glutamine is unstable in liquid media, degrading into ammonia and pyrrolidone carboxylic acid at physiological temperatures. This degradation reduces L-glutamine availability and can lead to toxic ammonia accumulation, negatively affecting cell metabolism. Therefore, many formulations are sold without L-glutamine, requiring users to add it fresh or use a stable dipeptide form like GlutaMAX™ Supplement to mitigate ammonia buildup.
Sodium pyruvate is another common supplement in some DMEM formulations, providing an alternative carbohydrate source for cellular energy. It can be particularly beneficial for cells under metabolic stress, at low densities, or those with impaired mitochondrial transport. Sodium pyruvate participates in various metabolic pathways, including glycolysis, and can be converted to acetyl-CoA to enter the TCA cycle, contributing to ATP production. It also offers protective effects, including antioxidant properties, by scavenging reactive oxygen species.
HEPES is an organic buffer sometimes added to DMEM to enhance its buffering capacity. While sodium bicarbonate is the primary buffering system (requiring a 5-10% CO2 environment), HEPES provides additional pH stability independent of CO2 concentration. This makes HEPES-buffered media useful for experiments involving extended handling of cells outside a CO2 incubator, where pH fluctuations could occur. HEPES is typically used at concentrations between 10 mM and 25 mM, with 25 mM common in some Gibco DMEM formulations.
Typical Cell Line Applications
High glucose DMEM is well-suited for culturing many mammalian cell lines, particularly those with high energy demands. Its rich nutrient profile supports the metabolic activity of rapidly dividing cells. Transformed cell lines, which often exhibit altered metabolism and increased glucose consumption, thrive in this medium. Certain primary cells also benefit from the elevated glucose content, supporting their growth and metabolic requirements.
Common cell lines cultured in high glucose DMEM include HeLa, HEK293, COS-7, and various fibroblast and hybridoma lines. HeLa cells, a human cervical cancer cell line, demonstrate robust growth in this medium due to their high metabolic rate. HEK293 cells, derived from human embryonic kidney cells, also proliferate well, often used for protein expression and viral production. The high glucose content directly supports the energetic needs of these actively growing and metabolically active cell types.
Supplementation, Storage, and Handling
DMEM is a basal medium, providing fundamental nutrients but generally requiring further supplementation for optimal cell growth. The most common supplement is Fetal Bovine Serum (FBS), typically added to a final concentration of 10%, to supply growth factors, hormones, and other macromolecules necessary for cell proliferation and attachment. Antibiotics, such as penicillin-streptomycin, are routinely included to prevent bacterial and fungal contamination.
Proper storage is important to maintain DMEM quality and efficacy. The medium should be refrigerated at 2-8°C and protected from light. Exposure to light, particularly fluorescent laboratory light, can degrade photosensitive components like riboflavin, leading to cytotoxic byproducts that can impair cell growth. Once opened, it is advised to use the medium within 6-8 weeks to ensure its integrity.
When handling DMEM, maintaining aseptic technique is important to prevent microbial contamination. All procedures should be performed in a sterile environment, such as a biosafety cabinet. Warming the medium to 37°C before adding it to cells is also a common practice, as it helps avoid temperature shock to cultured cells, promoting their continued health and growth.