FluxMPS™ Ham's F-10 Nutrient Mixture

About Ham's F-10 Nutrient Mixture

Ham's F-10 and Ham's F-12 are chemically defined, nutrient-rich cell culture media developed by Richard G. Ham at the University of Colorado to support the clonal growth of single Chinese hamster ovary (CHO) cells, an objective that required sustaining individual cells at very low densities under defined conditions, without reliance on serum or undefined biological extracts. They belong to a larger family of sequentially numbered formulations (the "F" series) developed by Ham in the late 1950s-1960s, each iteration tested against clonal growth efficiency as the quantitative readout. F-12 is a direct development of F-10, retaining the same qualitative amino acid and vitamin profiles but with substantially altered concentrations of several components, most notably an approximately 30-fold higher zinc sulfate level, along with the addition of putrescine and linoleic acid, thereby rendering it effective for low-density, protein-free CHO culture.

Both media share the same inorganic salt framework, the same 10-vitamin panel (including biotin and vitamin B12, which are absent from DMEM), the same nucleoside/nucleotide precursors (hypoxanthine and thymidine), and the same organic supplements (lipoic acid and sodium pyruvate). The key structural differences are the trace-element concentrations (especially zinc), the addition of putrescine and linoleic acid in F-12, the MgSO4 to MgCl2 salt change, and markedly higher concentrations of several amino acids and two vitamins (choline, myo-inositol) in F-12.

Origins and Development: Richard G. Ham and the Serum-Free Cloning Problem

By the late 1950s, growing a single mammalian cell into a clone essential for genetic analysis, mutagenesis, and selection of stable lines still depended on high serum concentrations or feeder cells. Ham recognized that the barrier was not a single missing factor but an incompletely defined nutrient environment whose inadequacies were masked by the serum's complex activity.

Working with near-diploid Chinese hamster (CHO) cells, the line initiated by Theodore T. Puck at the University of Colorado in 1957, Ham systematically developed a series of nutrient mixtures using single-cell plating efficiency (the fraction of individually plated cells that formed visible colonies) as his quantitative endpoint. Each formulation number marked an iteration in this optimization. Making clonal growth efficiency the disciplined, reproducible assay replaced subjective visual assessments of growth.

Ham's F-10 (1963)

Ham, R.G. (1963). "An improved nutrient solution for diploid Chinese hamster and human cell lines." Experimental Cell Research, 29: 515-526. PMID: 13952250. F-10 enabled consistent single-cell cloning of Chinese hamster cells under low-serum conditions, and serum-free growth in the presence of defined proteins (serum albumin and fetuin). Its notable features over earlier formulations were:

• One of the first defined media to incorporate copper (CuSO4) and zinc (ZnSO4) as trace elements (joining iron, already present in Eagle's media)
• A selective amino acid profile: very high arginine (211 mg/L), very low tryptophan (0.6 mg/L), low tyrosine (2.61 mg/L), and low branched-chain amino acids (isoleucine 2.6, valine 3.5)
• Inclusion of hypoxanthine (purine precursor), thymidine (deoxyribonucleoside), and lipoic acid (a cofactor)
• A dual-phosphate salt system (KH2PO4 + Na2HPO4) providing both mono- and dibasic phosphate

F-10 was also found to support human diploid cells, chromosome analysis of white blood cells, primary explants of rat, rabbit, and chicken tissues, and chick embryo cells.

Ham's F-12 (1965) — Direct Descendant of F-10

Ham, R.G. (1965). "Clonal growth of mammalian cells in a chemically defined, synthetic medium." Proceedings of the National Academy of Sciences USA, 53(2): 288-293. PMID: 14283412. F-12 was developed from F-10 (1963-1965) to achieve true protein-free clonal growth of CHO cells. In the 1965 PNAS paper, Ham demonstrated for the first time that single CHO cells could proliferate into clones in a fully chemically defined, protein-free medium.

• Zinc sulfate increased approximately 30-fold — from 0.029 mg/L (ZnSO4 * 7H2O) in F-10 to 0.863 mg/L in F-12, the single change most associated with improved plating efficiency and reproducibility for protein-free CHO cloning
• Addition of putrescine * 2HCl (0.161 mg/L), a polyamine precursor required for proliferation, found to substitute for a poorly defined serum activity
• Addition of linoleic acid (0.084 mg/L), an essential omega-6 fatty acid absent from F-10, providing a lipid source under serum-free conditions
• Large increases in several amino acids — proline (11.5 to 34.5), threonine (3.57 to 11.9), tryptophan (0.6 to 2.04), tyrosine (2.61 to 7.81), valine (3.5 to 11.7), isoleucine (2.6 to 3.94), lysine (29.3 to 36.5); arginine is essentially unchanged (211 to 210.7)
• Increases in two vitamins — choline chloride (0.698 to 13.96) and myo-inositol (0.541 to 18.0); several other vitamins (including thiamine, 1.0 to 0.34) actually decreased in F-12
• Magnesium source changed from MgSO4 (F-10) to MgCl2 (F-12), eliminating excess sulfate from the salt balance
• Iron and calcium are unchanged between F-10 and F-12 — both use ferrous sulfate heptahydrate (FeSO4 * 7H2O, 0.834 mg/L) and CaCl2 * 2H2O (44.1 mg/L)

F-12 became a medium of choice for myeloma and hybridoma cloning, primary rat hepatocytes, rat prostate epithelial cells, clonal toxicity assays, and the base of the widely used DMEM/F-12 hybrid. A tribute to Ham notes that F-12 became the starting medium for the systematic definition of individual growth-factor requirements across cell types, the platform from which the MCDB series grew.

Side-by-Side Composition Comparison

Ham's F-12 is provided here for reference and comparison; it is a distinct, separately formulated product from the F-10 family sold above.

Key Structural Differences Explained

The zinc difference is the defining feature. The approximately 30-fold increase in ZnSO4 * 7H2O from F-10 (0.029) to F-12 (0.863 mg/L) was the single most important change enabling protein-free CHO cloning. Zinc is required for numerous metalloenzymes, receptors, and transcription factors; at very low cell densities, the per-volume zinc requirement is not met by trace contamination, so it must be supplied at a defined, elevated concentration.

Putrescine supports polyamine-dependent proliferation. Putrescine (0.161 mg/L) is the diamine precursor to spermidine and spermine, essential for DNA synthesis, ribosome function, and cell division, partially bypassing the polyamine supply that serum normally provides.

Linoleic acid is an essential fatty acid. Linoleic acid (0.084 mg/L, free fatty acid) supplies the essential omega-6 fatty acid for membrane phospholipid synthesis that serum albumin-bound fatty acids would otherwise provide; cells cannot synthesize it de novo.

myo-Inositol is 33x higher in F-12 (18.0 vs 0.541 mg/L). Inositol is a component of phosphatidylinositol, a key membrane phospholipid and signaling intermediate whose requirement rises sharply in single-cell cultures.

Choline is 20x higher in F-12 (13.96 vs 0.698 mg/L), supporting phosphatidylcholine synthesis and the higher membrane biosynthetic demand of rapidly proliferating single-cell clones under protein-free conditions.