Regeneration: Hope for new hair

Adult mice can regenerate hair follicles and hair. The results help resolve a 50-year-long debate and may aid in the design of new treatments for wounds, hair loss and other degenerative skin disorders.
For half a century, most people believed that mammalian hair follicles form only during development, and that loss of adult follicles is permanent. George Cotsarelis and colleagues now show this is not the case, at least for adult mice with skin wounds. Wounding, they report, triggers new hair-producing follicles to form. Exposure to Wnt signalling — a genetic pathway involved in normal hair follicle development and cycling — following wounding increases the number of regenerated hair follicles. And Wnt signalling inhibition after regrowth of the epithelium prevents new follicles from forming.
The results suggest that mammalian skin can respond to wounding with plasticity and a much greater regenerative capacity than was previously believed. It's thought that wounding triggers an embryonic-like state in the skin which provides a window for hair follicle regeneration via the Wnt signalling pathway.
CONTACT
George Cotsarelis (University of Pennsylvania School of Medicine, Philadelphia, PA, USA)
Tel: +1 215 898 9967; E-mail: cotsarel@mail.med.upenn.edu

Cheng-Ming Chuong (University of Southern California, Los Angeles, CA, USA) N&V author
Tel: +1 323 442 1296; E-mail: chuong@pathfinder.usc.edu