Histologic Study of the Regeneration Process of Human Hair Follicles Grafted onto SCID Mice after Bulb Amputation

Abstract

This study examines histologically the degeneration and subsequent regeneration processes of human hair follicles whose bulb is severely damaged. Human scalp hair follicles were isolated and grafted onto immunodeficient mice after their bulb was amputated. On day 14, thickening and corrugation of the vitreous membrane, apoptosis of follicular keratinocytes, and regression of the lower portion of the follicles were observed. By day 20, mesenchymal cells had accumulated around the lower end of the follicles. From day 14 through 50, the follicular regression and apoptosis continued, and between days 30 and 40 the follicles became maximally shortened, and the vitreous membrane disappeared. By day 50 the lower end of the follicles had become cup-shaped, and the cup surrounded an aggregate of mesenchymal cells that corresponded to the dermal papilla. By day 60, all the grafted follicles had developed into anagen VI follicles, and the apoptosis had ceased. These results indicate that human scalp hair follicles whose bulb is completely destroyed enter into dystrophic telogen after restoration of the dermal papilla, then into anagen, and that the duration of the dystrophic telogen is shorter than that of the normal hair cycle.

Cultured Peribulbar Dermal Sheath Cells Can Induce Hair Follicle Development and Contribute to the Dermal Sheath and Dermal Papilla

“…Surgical implantation of microdissected follicular DS to amputated rodent vibrissae promoted the formation of new DP and hair ¢ber . Various combinations of di¡erentiated DS tissue implanted in association with di¡erentiated, epidermalderived hair follicle cells permit the redevelopment of DP and formation of hair-follicle-like structures (Oliver, 1967a;Kobayashi and Nishimura, 1989;Reynolds and Jahoda, 1991;Matsuzaki et al, 1996;Hashimoto et al, 2000Hashimoto et al, , 2001. A recent report involving transgender implantation of microdissected human DP and DS indicated DS successfully induced hair follicle formation (Reynolds et al, 1999).…”

Hair Regeneration from Transected Follicles in Duplicative Surgery

“…The most widely used technique for hair transplantation is the implantation of individual hair follicle units (FUs), although the availability of donor hairs limits it. Attempts to create hairlines using bisected hair follicles have been previously reported 1–5 . This method is based on the transection of one FU into two growing follicles to regenerate new hairs.…”

“…Attempts to create hairlines using bisected hair follicles have been previously reported. [1][2][3][4][5] This method is based on the transection of one FU into two growing follicles to regenerate new hairs. The general consensus shows 50% to 70% of success using this procedure, 1 but the biological basis of the capacity of each half to regenerate the entire hair has not been elucidated.…”

Versican targeting by RNA interference suppresses aggregative growth of dermal papilla cells

“…It was previously found that dermal sheath cells could gather to form DPs and induce HF formation after the HF bulbar zone was removed 26,27 . During the process of HF embryo bud formation, hypodermal cells aggregate and form DPs, which promote the development of HFs 28 .…”