Extracellular magnesium and in vitro cell differentiation: different behaviour of different cells.

The contribution of magnesium to cell differentiation is not clear. Some studies indicate that low extracellular magnesium promotes cell differentiation, while others reach opposite conclusions. We evaluated the effects of different concentrations of extracellular magnesium on the differentiation of three in vitro experimental models: human endothelial cells seeded onto Matrigel; phorbol ester-treated myeloid leukemia U937 cells; and 3T3-L1 pre-adipocytes exposed to a hormonal cocktail containing dexamethasone and insulin. The differentiation of endothelial cells and pre-adipocytes seems to be independent of extracellular Mg concentration. Conversely, magnesium deficiency retards, while high extracellular magnesium accelerates phorbol ester-induced U937 cell differentiation, probably by interfering with calcium homeostasis or with the activity of kinases. We conclude that the extracellular magnesium concentration affects the differentiation of various cell types.