Hair Growth on Nude Mice Due to Cyclosporin A

The study investigated the effects of cyclosporin A (CsA) on hair growth in nude mice, revealing that CsA induced dose-dependent hair growth when administered orally, topically, or subcutaneously. Hair growth began 7 days after treatment and was evident after 3 weeks, with the pattern following the natural hair growth of the mice. No hair growth was observed in control mice treated with olive oil alone. Histological analysis showed no structural differences in skin and hair between treated and control mice, and the number of hair follicles did not significantly increase. Hair growth ceased after stopping CsA treatment but resumed with retreatment. However, older mice (9 months) did not exhibit hair growth after a 4-week CsA treatment.