Hair follicle dermal sheath cells: unsung participants in wound healing

The dermal sheath that surrounds the outside of the hair follicle contains progenitor cells that maintain and regenerate the dermal papilla, a key com ponent for hair growth. Our contention is that dermal sheath cells have oth er roles. We believe that they can become wound healing fibroblasts and per form an important function in the repair of skin dermis after injury. The d ermal sheath has close developmental and anatomical parallels with follicle outer root sheath, the epithelial component that contains the stem cells r esponsible for replacing skin epidermis. Dermal sheath cells also have a my ofibroblast or wound healing phenotype, and in animals with high follicle d ensities differences in wound healing are observed in conjunction with chan ges in the hair growth cycle. Similarly, in human beings there are apparent differences in wound healing responses between hairy and non-hairy body si tes. Moreover, clinical and experimental data suggest that the involvement of follicle-derived dermal cells results in qualitatively Improved dermal r epair. Therefore, in a therapeutic context, hair follicle dermal cells prov ide an accessible option for the creation of dermal or full skin equivalent s that could both improve wound healing and reduce scarring. Indeed, given the inductive properties of adult hair follicle dermal cells, it is reasona ble to envisage a tissue engineering approach for the production of a skin equivalent that will grow hair follicles when grafted.