Regeneration of a New Hair Follicle from the Upper Half of a Human Hair Follicle in a Nude Mouse

In a study from 2002, researchers investigated the regenerative capacity of human hair follicles (HFs) by transplanting different segments of transected HFs onto athymic nude mice. The HFs were obtained from patients undergoing hair transplantation and were cut into different segments before being transplanted. A total of 12 HFs were transplanted for each group. After 16 weeks, only one upper portion of a bisected human HF was able to regenerate a completely new, pigmented hair that was 10 mm long and about 2.5 times smaller in diameter than a normal human anagen hair. Histologic analysis confirmed the presence of a completely reformed follicle with all follicular structures. However, the overall success rate of graft survival was very low, with no visible hair fiber reproduced in other HF implants. The study concluded that the upper half of a human HF can regenerate a complete new HF in a nude mouse, and the success rate of grafting might be improved by modifying the implantation technique. This work was supported by the International Society of Hair Restoration Surgery.