Thrombospondin-1 Plays a Critical Role in the Induction of Hair Follicle Involution and Vascular Regression During the Catagen Phase

The study explored the role of thrombospondin-1 (TSP-1) in hair follicle cycling, particularly during the catagen phase, using transgenic mice. TSP-1 expression increased during catagen, acting as an antiangiogenic factor that induced vascular regression and hair follicle involution. Mice overexpressing TSP-1 experienced delayed and reduced hair regrowth due to decreased perifollicular vascularization, while TSP-1 deficient mice had prolonged anagen phases with increased vascularization. These findings indicated that TSP-1 played a critical role in initiating follicle regression by inhibiting angiogenesis, suggesting its potential as a target for hair growth modulation therapies.