Biphasic Effects of Minoxidil on the Proliferation and Differentiation of Normal Human Keratinocytes

This 25-year-old study explored the effects of minoxidil on the proliferation and differentiation of normal human keratinocytes. The study found that minoxidil had biphasic effects on the proliferation and differentiation of NHK, stimulating proliferation at micromolar doses while antiproliferative, pro-differentiative, and partially cytotoxic effects were observed with millimolar concentrations. The authors hypothesize that minoxidil's hypertrichotic activity in vivo is possibly mediated by the maintenance of proliferative potential in follicular keratinocytes precociously committed to differentiation. The study provides insight into the pharmacological activity of minoxidil and its target cells in hair follicles.