[Effect of minoxidil on DNA synthesis in cultured fibroblasts from healthy skin or keloids].

A potential therapeutic role of minoxidil in fibrotic or sclerotic conditions, such as keloids, has been suggested on the basis of its reported ability to inhibit the proliferation of human dermal fibroblasts. We have studied the effect of minoxidil on 3H-deoxythymidine uptake in cultures of human dermal fibroblasts derived from lesional and non-lesional skin from patients with keloids. The effect of the addition of fetal bovine serum, plasma and growth factors (insulin, EGF, PDGF, FGF and beta-TGF) to the medium has also been studied. Minoxidil, at concentrations ranging from 500 to 1,000 microM., caused an increase in DNA synthesis, which was proportional to the initial degree of fibroblast activation. Concentrations higher than 1,000 microM. caused a cytotoxic effect. Some reservations arise on the potential therapeutic use of minoxidil in conditions characterized by increased fibroblast proliferation, given the narrow margin between activation of DNA synthesis and cytotoxicity we have found in our experimental model.