What Do We Know About Hair Growth Induced by Wounding and Its Therapeutic Applications?

BACKGROUND Many studies have reported the role of hair follicles (HFs) in the wound healing response, and vice versa, the creation of superficial injuries may stimulate hair growth, which has encouraged new treatments for hair loss. OBJECTIVE To review the phenomenon of wound-induced hair growth and the usefulness of therapeutic procedures based on skin wounding in androgenetic alopecia (AGA). METHODS A literature search was conducted to review cases of localized hypertrichosis induced by wounds and the role of microneedling, fractional laser, and scalp threading as monotherapy for AGA. RESULTS Localized hypertrichosis has been extensively reported after bone fractures, burn injury, chronic venous ulcer, etc. Only 2 cases of wound-induced hair neogenesis in humans have been reported. As monotherapy for AGA, 1 of 3 studies of microneedling, 4 of 6 of fractional lasers, and 2 of 3 studies of scalp threading show good efficacy. CONCLUSION Certain types of wounds seem to stimulate localized hair growth in humans, but the underlying mechanism is unclear. Reports on wound-induced HF neogenesis in humans are anecdotal and questions remain as to whether this is a true phenomenon in humans. Further clinical studies are needed before recommending wound-induced hair growth procedures as therapies for AGA.