Cell culture medium

A cell culture medium is a mixed solution used for culturing cells in vitro, which artificially simulates the nutritional environment for cell growth in vivo.

I. Main Components

1. Nutrients
   • Amino Acids: They are the basic raw materials for cells to synthesize proteins. Different types of cells have different requirements for various amino acids, but generally, essential amino acids are indispensable. For example, L – glutamine is very important in cell metabolism. It is not only a raw material for protein synthesis but also participates in energy metabolism and nucleic acid synthesis.
   • Carbohydrates: They mainly provide energy for cells. The most commonly used is glucose. Cells can convert glucose into ATP (adenosine triphosphate) through glycolysis, aerobic respiration, and other pathways to meet their energy needs.
   • Vitamins: They play important roles in cell growth, proliferation, and metabolic regulation. For example, various components of the vitamin B family participate in intracellular enzymatic reactions, and folic acid is crucial for DNA synthesis.
   • Inorganic Salts: They maintain the osmotic pressure balance and acid – base balance of cells. Common ones include sodium ions, potassium ions, calcium ions, and magnesium ions, which are important in regulating cell membrane potential and participating in cell signaling transduction.
2. Growth Factors
   • They are a class of proteins that regulate cell growth, proliferation, and differentiation. For example, epidermal growth factor (EGF) can stimulate the proliferation of various epithelial and endothelial cells; fibroblast growth factor (FGF) promotes the growth of fibroblasts and other cells and also participates in physiological processes such as angiogenesis.
3. Hormones
   • Some cells require specific hormones during culturing. For example, insulin can regulate the uptake and utilization of glucose by cells and is very important for culturing some cells with high requirements for glucose metabolism; thyroid hormones can affect the metabolic rate and differentiation state of cells.
4. Other Additives
   • Serum: It is a commonly used additive in cell culture media. Serum contains various nutrients such as growth factors, hormones, proteins, and lipids. For example, fetal bovine serum is rich in substances required for cell growth and can promote the adherent growth and proliferation of cells. However, the components of serum are complex, with batch – to – batch variations, and may contain some unknown factors, which limit its application to some extent.
   • Buffering Substances: Acidic metabolites are produced during cell culture, resulting in a decrease in the pH of the medium. To maintain a stable pH, buffering substances are often added to the medium, such as sodium bicarbonate and HEPES (4 – hydroxyethylpiperazineethanesulfonic acid). Sodium bicarbonate regulates the pH through equilibrium with carbon dioxide, and HEPES is a substance with strong buffering capacity within a certain pH range.