Minimum Essential Medium (MEM), developed by Harry Eagle, is one of the most widely used of all synthetic cell culture media. Early attempts to cultivate normal mammalian fibroblasts and certain subtypes of HeLa cells revealed that they had specific nutritional requirements that could not be met by Eagle's Basal Medium (BME). Subsequent studies using these and other cells in culture indicated that additions to BME could be made to aid growth of a wider variety of fastidious cells. MEM, which incorporates these modifications, includes higher concentrations of amino acids so that the medium more closely approximates the protein composition of mammalian cells. MEM has been used for cultivation of a wide variety of cells grown in mono-layers. Optional supplementation of non-essential amino acids to the formulations that incorporate either Hanks' or Eagles' salts has broadened the usefulness of this medium. The formulation has been further modified by optional elimination of calcium to permit the growth of cells in suspension.

The following table contains a large selection of MEM formulations. Selection of the most appropriate formulation for your application requires an understanding of the way these formulations are constructed and offered.

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Product #	Product Name	Description	Application
M 2279	Minimum Essential Medium Eagle	Liquid With Earle's salts and sodium bicarbonate Without L-glutamine, supplement with 0.292 gm/L of L-glutamine Sterile-filtered Endotoxin tested Cell culture tested	Essentially the same as the original formula. Generally used to grow attached cell lines, such as fibroblasts, in the presence of FBS, calf or horse sera.
M 4655	Minimum Essential Medium Eagle	Liquid With Earle's salts, L-glutamine and sodium bicarbonate Sterile-filtered Endotoxin tested Cell culture tested	Essentially the same as the original formula. Generally used to grow attached cell lines, such as fibroblasts, in the presence of FBS, calf or horse sera.
M 0275	Minimum Essential Medium Eagle (10x)	Liquid With Earle's salts Without L-glutamine and sodium bicarbonate Supplement with 0.292 gm/L of L-glutamine and 2.2 gm/L of sodium bicarbonate at 1x pH 5.1-5.5 at 10x Sterile-filtered Endotoxin tested Cell culture tested	Essentially the same as the original formula. Generally used to grow attached cell lines, such as fibroblasts, in the presence of FBS, calf or horse sera. The L-glutamine and sodium bicarbonate are added to the medium after dilution to 1x and pH adjustment.
M 0268	Minimum Essential Medium Eagle	Powder With Earle's salts and L-glutamine Without sodium bicarbonate, supplement with 2.2 gm/L sodium bicarbonate Formulated at 9.6 grams of powder per liter of medium Cell culture tested	Essentially the same as the original formula, except it is provided as a powder. Generally used to grow attached cell lines, such as fibroblasts, in the presence of FBS, calf or horse sera.
M 5650	Minimum Essential Medium Eagle	Liquid With Earle's salts, non-essential amino acids and sodium bicarbonate Without L-glutamine, supplement with 0.292 gm/L of L-glutamine Sterile-filtered Endotoxin tested Cell culture tested	Same as M 2279, with one major difference. It contains 19 amino acids. The essential amino acids and the non-essential amino acids: L-ala; L-asn; L-asp; L-glu; L-gly; L-pro and L-ser. May be preferred for growth of adherent cells in the presence of reduced serum or as a base for development of a serum free medium.
M 0643	Minimum Essential Medium Eagle	Powder With Earle's salts, L-glutamine and non-essential amino acids Without sodium bicarbonate, supplement with 2.2 gm/L sodium bicarbonate Formulated at 9.7 grams of powder per liter of medium Cell culture tested	Offered as powder form of M 5650 It contains 19 amino acids. The essential amino acids and the non-essential amino acids: L-ala; L-asn; L-asp; L-glu; L-gly; L-pro and L-ser. May be preferred for growth of adherent cells in the presence of reduced serum or as a base for development of a serum free medium.
M 3024	Minimum Essential Medium Eagle Modified	Powder With Earle's salts and non-essential amino acids Without L-glutamine, phenol red, and sodium bicarbonate. Supplement with 0.292 gm/L L-glutamine; with 2.2 gm/L of sodium bicarbonate Formulated at 9.4 grams of powder per liter of medium Cell culture tested	It contains 19 amino acids. The essential amino acids and the non-essential amino acids: L-ala; L-asn; L-asp; L-glu; L-gly; L-pro and L-ser. May be preferred for growth of adherent cells in the presence of reduced serum or as a base for development of a serum free medium. Same as M 0643, except that L-glutamine may be added at time of use.
M 4144	Minimum Essential Medium Eagle Modified	Powder With Earle's salts Without phenol red, L-glutamine and sodium bicarbonate. Supplement with 0.292 gm/L L-glutamine; with 2.2 gm/L of sodium bicarbonate Formulated at 9.3 grams of powder per liter of medium Cell culture tested	Essentially the same as the original formula, except it is provided as a powder and without phenol red. Generally used to grow attached cell lines, such as fibroblasts, in the presence of FBS, calf or horse sera. Media without phenol red is often preferred for work with stem cells and in cell cloning.
M 7278	Minimum Essential Medium Eagle HEPES Modification	Liquid With Earle's salts, 25 mM HEPES and sodium bicarbonate Without L-glutamine; supplement with 0.292 gm/L of L-glutamine Sterile-filtered Endotoxin tested Cell culture tested	Same as M 2279, except that it is supplemented with 25 mM HEPES. HEPES increases the buffer strength of the medium and raises the maximum buffering range. Recommended for cells that grow better at a pH above 7.2.
M 2645	Minimum Essential Medium Eagle HEPES Modification	Powder With Earle's salts, L-glutamine and HEPES Without sodium bicarbonate; supplement with 2.2 gm/L sodium bicarbonate Formulated at 14.2 grams of powder per liter of medium Cell culture tested	Similar to M 7278, except that it is a powder without sodium bicarbonate. HEPES increases the buffer strength of the medium and raises the maximum buffer range. Leaving the bicarbonate out gives the investigator greater control over the buffer system. Recommended for cells that grow better at a pH above 7.2.
M 8042	Minimum Essential Medium Eagle Alpha Modification	Liquid With ribonucleosides and deoxyribonucleosides and sodium bicarbonate Without L-glutamine, supplement with 0.292 gm/L of L-glutamine Sterile-filtered Endotoxin tested Cell culture tested	This is the most enriched variation of the MEM formulation offered. It contains all 21 normal amino acids, some at increased concentrations. In addition, it contains 5 additional vitamins. See formulation for details. Often used in cytogenetic analysis when supplemented with FBS.
M 4526	Minimum Essential Medium Eagle Alpha Modification	Liquid With sodium bicarbonate Without L-glutamine, supplement with 0.292 gm/L of L-glutamine Without ribonucleosides and deoxyribonucleosides Sterile-filtered Endotoxin tested Cell culture tested	Same as M 8042, except that it lacks the ribonucleosides and deoxyribonucleosides. This is the most enriched variation of the MEM formulation offered. It contains all 21 normal amino acids, some at increased concentrations. In addition, it contains 5 additional vitamins.
M 0644	Minimum Essential Medium Eagle Alpha Modification	Powder With L-glutamine, ribonucleosides and deoxyribonucleosides. Without sodium bicarbonate; supplement with 2.2 gm/L sodium bicarbonate Formulated at 10.2 grams of powder per liter of medium Cell culture tested	This is the most enriched variation of the MEM formulation offered. It contains all 21 normal amino acids, some at increased concentrations. In addition, it contains 5 additional vitamins. Often used in cytogenetic analysis when supplemented with FBS. Offered as a powder form of M 8042.
M 0894	Minimum Essential Medium Eagle Alpha Modification	Powder With L-glutamine Without ribonucleosides, deoxyribonucleosides and sodium bicarbonate; supplement with 2.2 gm/L sodium bicarbonate Formulated at 10.1 grams of powder per liter of medium Cell culture tested	This is the most enriched variation of the MEM formulation offered. It contains all 21 normal amino acids, some at increased concentrations. In addition, it contains 5 additional vitamins. Offered as a powder form of M 4526.
M 2414	Minimum Essential Medium Eagle Modified	Liquid With Earle's salts and reduced sodium bicarbonate Without L-glutamine; supplement with 0.292 gm/L of L-glutamine Sterile-filtered Endotoxin tested Cell culture tested	Same as M 2279, except that the sodium bicarbonate concentration is reduced to 0.85 gm/L. Recommended for use in a carbon dioxide-free culture system. May also be supplemented with HEPES to raise the buffering range.
M 3786	Minimum Essential Medium Eagle	Liquid With Earle's salts, sodium bicarbonate and L-glutamine Without sodium phosphate; supplement with 0.122 gm/L of sodium phosphate monobasic (anhydrous) Sterile-filtered Endotoxin tested Cell culture tested	Same as M 2279, except that sodium phosphate has been left out of the formulation. Recommended for investigators who want to use a formulation that is totally buffered by sodium bicarbonate.
M 8028	Minimum Essential Medium Eagle Joklik Modification	Liquid With sodium bicarbonate Without calcium chloride and L-glutamine, supplement with 0.292 gm/L of L-glutamine Sterile-filtered Endotoxin tested Cell culture tested	Calcium and magnesium support cell adhesion. Calcium has been removed from this formulation. However, it still contains magnesium chloride. Recommended for suspension cultures.
M 0518	Minimum Essential Medium Eagle Joklik Modification	Powder With L-glutamine Without calcium chloride and sodium bicarbonate, supplement with 2.0 gm/L sodium bicarbonate Formulated at 11.2 grams of powder per liter of medium Cell culture tested	Calcium and magnesium support cell adhesion. Calcium has been removed from this formulation. However, it still contains magnesium chloride. Recommended for suspension cultures. Offered as the powder form of M 8028
M 8167	Minimum Essential Medium Eagle Spinner Modification (S-MEM)	Liquid With Earle's salts and sodium bicarbonate Without calcium chloride and L-glutamine; supplement with 0.292 gm/L of L-glutamine Sterile-filtered Endotoxin tested Cell culture tested	Calcium and magnesium support cell adhesion. Calcium has been removed from this formulation. However, it still contains magnesium sulfate. Recommended for suspension cultures.
M 4767	Minimum Essential Medium Eagle Spinner Modification (S-MEM)	Powder With L-glutamine Without calcium chloride and sodium bicarbonate Formulated at 10.4 grams of powder per liter of medium Cell culture tested	Calcium and magnesium support cell adhesion. Calcium has been removed from this formulation. However, it still contains magnesium sulfate. Recommended for suspension cultures Offered as the powder form of M 8167
M 7395	Minimum Essential Medium Eagle D-Valine Modification	Powder With Earle's salts, L-glutamine and D-valine substituted for L-valine. Without sodium bicarbonate; supplement with 2.2 gm/L sodium bicarbonate. Formulated at 9.6 grams of powder per liter of medium Cell culture tested	Same formulation as M 2279 except that D-valine has been substituted for L-valine. Recommended for the preferential selection and growth of cells possessing D-amino acid oxidase, such as epithelial and Schwann cells.
M 7270	Minimum Essential Medium Eagle	Powder With Earle's salts and L-glutamine. Without L-leucine, L-lysine, L-methionine and sodium bicarbonate Supplement with 0.052 gm/L of L-leucine; 0.0725 gm/L of L-lysine; 0.015 gm/L of L-methionine and 2.2 gm/L of sodium bicarbonate. Formulated at 9.4 grams of powder per liter of medium Cell culture tested	Same as M 0268, except that 3 essential amino acids are not included in the powder. This base formulation is particularly suitable for studies of cell protein metabolism and label-tagged amino acid studies. Offered as the powder form of M 2289
M 3911	Minimum Essential Medium Eagle	Liquid With Earle's salts, sodium bicarbonate and L-glutamine Without L-methionine; supplement with 0.015 gm/L L-methionine Sterile-filtered Endotoxin tested Cell culture tested	Same as M 4655, except that L-methionine is not included. Useful for studies of methionine metabolism.
M 2289	Minimum Essential Medium Eagle Modified	Liquid With Earle's salts and sodium bicarbonate Without L-methionine, L-cystine, and L-glutamine Supplement with 0.313 gm/L of L-cystine dihydrochloride; 0.292 gm/L of L-glutamine and 0.015 gm/L of L-methionine. Sterile-filtered Endotoxin tested Cell culture tested	Same as M 2279, except that 3 essential amino acids are not included. This base formulation is particularly suitable for studies of cell protein metabolism and label-tagged amino acid studies.
M 0769	Minimum Essential Medium Eagle Auto-Mod^TM	Powder Modified for autoclaving With Earle's salts Without L-glutamine and sodium bicarbonate. Supplement with 0.292 gm/L L-glutamine; with 2.2 gm/L of sodium bicarbonate Formulated at 9.4 grams of powder per liter of medium Cell culture tested	Modification of the original MEM formulation. Contains a succinate buffering system. See formulations table for specific information. Medium may be autoclaved.
M 5775	Minimum Essential Medium Eagle	Liquid With Hanks' salts and sodium bicarbonate Without L-glutamine, supplement with 0.292 gm/L of L-glutamine Sterile-filtered Endotoxin tested Cell culture tested	Modification of the original MEM formulation. Earle's salts have been replaced with Hanks' salts. Since the bicarbonate concentration is substantially lower, this medium has a substantially reduced buffering capacity. Same as M 4780, except that the L-glutamine may be added at time of use.
M 4780	Minimum Essential Medium Eagle	Liquid With Hanks' salts, L-glutamine and sodium bicarbonate Sterile-filtered Endotoxin tested Cell culture tested	Modification of the original MEM formulation. Earle's salts have been replaced with Hanks' salts. Since the bicarbonate concentration is substantially lower, this medium has a substantially reduced buffering capacity.
M 9288	Minimum Essential Medium Eagle (10x)	Liquid With Hanks' salts Without L-glutamine and sodium bicarbonate Supplement with 0.292 gm/L of L-glutamine and 0.35 gm/L of sodium bicarbonate at 1x pH 5.2-5.4 at 10x Sterile-filtered Endotoxin tested Cell culture tested	This is the 10x concentrated version of M 5775 and M 4780. L-glutamine and sodium bicarbonate are added after the medium has been diluted to 1x and the pH has been adjusted.
M 4642	Minimum Essential Medium Eagle	Powder With Hanks' salts and L-glutamine. Without sodium bicarbonate; supplement with 0.35 gm/L sodium bicarbonate Formulated at 10.7 grams of powder per liter of medium Cell culture tested	Modification of the original MEM formulation. Earle's salts have been replaced with Hanks' salts. Since the bicarbonate concentration is substantially lower, this medium has a substantially reduced buffering capacity.
M 3149	Minimum Essential Medium Eagle Modified	Powder With Hanks' salts and non-essential amino acids Without L-glutamine, phenol red and sodium bicarbonate Supplement with 0.292 gm/L of L-glutamine Formulated at 10.5 grams of powder per liter of medium Cell culture tested	Modification of the original MEM formulation. Earle's salts have been replaced with Hanks' salts. Since the bicarbonate concentration is substantially lower, this medium has a substantially reduced buffering capacity. It contains 19 amino acids. The essential amino acids and the non-essential amino acids: L-ala; L-asn; L-asp; L-glu; L-gly; L-pro and L-ser. May be preferred for growth of adherent cells in the presence of reduced serum or as a base for development of a serum free medium.
M 1018	Minimum Essential Medium Eagle	Powder With Hanks' salts, L-glutamine and non-essential amino acids Without sodium bicarbonate; supplement with 0.35 gm/L sodium bicarbonate Formulated at 10.8 grams of powder per liter of medium Cell culture tested	Modification of the original MEM formulation. Earle's salts have been replaced with Hanks' salts. Since the bicarbonate concentration is substantially lower, this medium has a substantially reduced buffering capacity. It contains 19 amino acids. The essential amino acids and the non-essential amino acids: L-ala; L-asn; L-asp; L-glu; L-gly; L-pro and L-ser. May be preferred for growth of adherent cells in the presence of reduced serum or as a base for development of a serum free medium.

Medium Selection Information

Most formulations are offered in both a powder and a liquid form. In addition, most formulations are offered as a complete medium or in deficient variations that allow the user to supplement with common components such as bicarbonate, glutamine or calcium. These variations provide more flexibility and control over the ultimate use and suitability of the medium.

Most of the formulations offered contain the original Earle's salts. However, a number of formulations contain Hanks' salts. Both of these phosphate and bicarbonate buffered saline solutions contain the same ions: calcium; magnesium; potassium; sodium,and phosphate. They differ in the concentrations of calcium, sodium and in the buffer component. Hanks' buffered salts solution contains a substantially lower concentration of sodium bicarbonate than does Earle's buffered salts.

The original MEM formulation contained Earle's salts and a group of amino acids generally referred to as essential amino acids. They were considered essential because the cells for which the medium was developed would not grow in their absence. The 12 essential amino acids are: L-arginine; L-cystine; L-glutamine; L-histidine; L-isoleucine; L-leucine; L-methionine; L-phenylalanine; L-threonine; L-tryptophan; L-tyrosine; and L-valine.

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