Minimum Essential Medium Eagle

Preparation Method: Add 5% less distilled water than the desired total volume to a mixing container just large enough to hold the final media volume. Add powdered medium to room temperature (20 -30°C) water with gentle stirring. Do not heat water. Rinse inside of pouch to remove all traces of powder. Adding 2000 mg of NaHCO3 per L of medium will adjust the pH to between 7.0 - 8.0. Closely monitor the pH while adding NaHCO3 until pH is in this range. MP Biomedicals catalog number 091688349 is a ready-to-use 7.5% solution of Sodium Bicarbonate. This solution can be used to adjust the pH by adding 0.27 mL per L of media. Dilute the medium to the desired volume with distilled water and stir until dissolved. Do not overmix. Adjust the pH to 0.2 to 0.3 units below the desired final working pH by slowly adding, with stirring, either 1N NaOH or 1N HCl. The pH will usually rise between 0.1 - 0.3 units upon filtration. Keep the container closed until the medium is filtered. Process the medium immediately into sterile containers by membrane filtration using a 0.2μm filter. We recommend using a positive pressure system.

Nutritional needs of normal mammalian fibroblasts and certain HeLa cell subtypes could not be met by Eagle’s earlier medium Basal Medium Eagle (BME). This led to the development of MEM incorporating specific modifications such as higher amino acid concentrations for the cultivation of fastidious cells.

Minimum Essential Medium Eagle (Modified), with Earle's Salts and L-Glutamine, without Sodium Bicarbonate has demonstrated the ability to support a variety of normal and transformed cells in culture and contains Earle’s Balanced Salts, which makes it suitable for use in atmospheres charged with CO2 gas. It may be used to support the growth of a variety of suspension or adherent mammalian cells, including HeLa, BHK-21, 293, HEP-2, HT-1080, MCF-7, SP2/0, CHO. fibroblasts and primary rat astrocytes, with proper supplementation. MEM serves as a general use medium ideal for the growth and maintenance of a wide range of mammalian cell types.

Minimum Essential Medium Eagle (Modified), with Earle's Salts and L-Glutamine, without Sodium Bicarbonate was originally prepared by Harry Eagle and is one of the most popular cell culture media. The formulation differs from the original in that the concentrations of some of the vitamins have been increased slightly; in some, the amino acids differ by decimal amounts. In some formulation, the MgSO4 concentration differs from that of Eagle but agrees with that quoted by Parker (Parker quotes 200.00 mg/liter MgSO4.7H2O).