Cell medium ingredients include nutrients (both organic and inorganic), vitamins, salts, O₂ and CO₂ gas phases, proteins (from defined or undefined sources), carbohydrates, cytokines, growth factors, and cofactors.

Media should be changed every 2 to 3 days. However, media is best changed when cell density reaches a healthy level, so this also depends on the growth rate of your cell culture. Most media also contain a pH indicator that changes color to yellow when pH drops, which is a sign of nutrient depletion and waste accumulation.

1. Serum-containing media - basal media supplemented with undefined biological materials such as serum or cell extracts.
2. Serum-free, animal component-containing media - basal medium supplemented with defined proteins, growth factors, and cytokines from animal sources;
3. Serum-free, xeno-free medium - basal media supplemented with defined proteins, growth factors, and cytokines from human origin only.
4. Animal component-free, chemically defined medium - basal medium composed of material from chemically defined sources.

Cell culture medium provides nutrients and growth factors necessary for cell proliferation. A typical basal cell culture medium is composed of amino acids, carbohydrates, vitamins, inorganic salts, glucose, trace elements, and a buffer system to maintain a stable pH. Traditionally, animal-derived serum is used to supplement basal media to provide a source of growth factors. Now, serum-free, chemically defined formulations are highly favored.

Serum-free media are media designed to grow cells in the absence of animal-derived serum. Serum-free media include chemically defined media, which are free of any animal components or hydrolysates.

Serum-free media allows cell culture to be performed under a defined set of conditions, limiting batch-to-batch variability. It also simplifies purification and downstream processing.

Xeno, derived from the Greek word “xenos”, means “foreigner.” A xeno-free media is a culture medium with a formulation that only contains human-derived components and not any other species such as bovine or porcine.

Serum-free media are free from any serum (from all animal species) but can include other animal components (such as HSA and BSA), while xeno-free is free of components from non-human animal species but can include human serum.

Each medium should be stored according to the manufactured protocols and recommendations. The typical expiration date is within 12-18 months of manufacture. When open and supplemented with other components under sterile conditions, media can generally be stored for 1-4 weeks, at 2-8°C, and protected from light. Classical media supplemented with serum antibiotics can be kept at 4°C for up to 4 weeks; serum-free media can be kept for up to 2 weeks.

Bleach should be added to unused media at ≥10% final concentration to treat any microorganism present before disposal.