Vellus-to-Terminal Hair Follicle Reconversion in Male Pattern Balding in a New Humanized Mouse Model of Androgenetic Alopecia and Its Promotion by Minoxidil and PRP

This study challenges the claim that fully miniaturized vellus (V) hair follicles (HFs) in androgenetic alopecia (AGA) cannot reconvert to terminal (T) HFs, even with therapy. Using a novel humanized AGA mouse model, biopsies from 10 male AGA patients were transplanted onto SCID/beige mice, which were then treated with either 5% topical minoxidil (MXL) or intradermal platelet-rich plasma (PRP) for 4 months. Quantitative histomorphometry showed a significant decrease in V and intermediate HFs and an increase in T HFs in treated transplants compared to donor scalp skin (p<0.05, p<0.01). This suggests that V-T reconversion is possible in long-standing AGA, promoted by both MXL and PRP, although intermediate HFs may be more responsive to reconversion than fully miniaturized V HFs, highlighting the importance of early intervention in AGA management.