Thymosin β4 increases hair growth by activation of hair follicle stem cells

SPECIFIC AIMSWe have explored the ability of thymosin β4 to promote hair growth in normal rats and mice and determined the mechanism by which thymosin β4 acts to promote hair growth by examining its effects on follicle stem cell growth, migration, differentiation, and protease production.PRINCIPAL FINDINGS1. Thymosin β4 promotes hair growth in normal rats and miceWhile studying wound healing in rat skin, we unexpectedly observed at the histological level increased hair growth at the wound margins 7 days after topical treatment with thymosin β4. We shaved the skin of healthy rats and applied thymosin β4 topically on one side of the shaved area and the control vehicle on the opposing lateral side of the same animal. After 7 days of treatment, we observed an increased number of anagen-phase hair follicles in skin areas treated with thymosin β4 (Fig. 1⤻ a, d). The number of anagen follicles was ∼twofold greater than in rats treated with vehicle alone. The increased number of hairs in anagen phase was retained...