Inhibited morphological terminal differentiation and enhanced proliferation of cultured mouse epidermal cells at different concentrations of dimethyl sulphoxide

Dimethyl sulphoxide (DMSO), at concentrations of 1-2%, induces terminal differentiation in several different cell types in vitro and enhances the growth of newborn mouse epidermal cells in primary culture under conditions that also permit terminal differentiation. We have found that DMSO concentrations approaching 4% reversibly inhibited (with little overt toxicity) terminal differentiation of normal epidermal cells from newborn SENCAR mice. Cells cultured in medium containing 4% DMSO and calcium in excess of 1 mM did not stratify extensively or slough large amounts of keratinized debris into the medium as occurred in control cultures, nor did they form large numbers of squamous cells or keratin bundles, as revealed by light and electron microscopy. The number of detergent-insoluble cornified envelopes was similarly reduced. Long-term growth of epidermal colonies in secondary culture was optimum in 1% DMSO, this concentration also permitting normal terminal differentiation of these cells. Since DMSO had these effects on epidermal cells in vitro, it may also affect epidermal cell proliferation and terminal differentiation in vivo, an important consideration should DMSO ever be approved for topical use in the US.