Elsevier

The Lancet

Volume 358, Issue 9291, 27 October 2001, Pages 1445-1448
The Lancet

Hypothesis
Hair follicle dermal sheath cells: unsung participants in wound healing

https://doi.org/10.1016/S0140-6736(01)06532-1Get rights and content

Summary

The dermal sheath that surrounds the outside of the hair follicle contains progenitor cells that maintain and regenerate the dermal papilla, a key component for hair growth. Our contention is that dermal sheath cells have other roles. We believe that they can become wound healing fibroblasts and perform an important function in the repair of skin dermis after injury. The dermal sheath has close developmental and anatomical parallels with follicle outer root sheath, the epithelial component that contains the stem cells responsible for replacing skin epidermis. Dermal sheath cells also have a myofibroblast or wound healing phenotype, and in animals with high follicle densities differences in wound healing are observed in conjunction with changes in the hair growth cycle. Similarly, in human beings there are apparent differences in wound healing responses between hairy and non-hairy body sites. Moreover, clinical and experimental data suggest that the involvement of follicle-derived dermal cells results in qualitatively improved dermal repair. Therefore, in a therapeutic context, hair follicle dermal cells provide an accessible option for the creation of dermal or full skin equivalents that could both improve wound healing and reduce scarring. Indeed, given the inductive properties of adult hair follicle dermal cells, it is reasonable to envisage a tissue engineering approach for the production of a skin equivalent that will grow hair follicles when grafted.

Section snippets

Supporting evidence

This idea originates in part from the striking developmental and structural parallels between the hair follicle epithelial outer root sheath and the dermal sheath. These segregate from interfollicular epidermis and dermis during early follicle development, and assume characteristic morphological and molecular phenotypes. Anatomically, both are contiguous with their equivalent tissues in skin, the outer root sheath with the epidermis, the dermal sheath with the upper or papillary dermis. The two

Testing of the hypothesis, and its significance for surgery/clinical dermatology

We suggest that the relative lack of large hair follicles over most areas of human skin contributes to inferior dermal repair and scar formation, but what are the clinical and practical implications of our hypothesis? Over the past two decades there have been significant improvements in the treatment of skin loss after burns or other injury and skin has become one of the main targets for tissue engineering projects. Of the two main tissues comprising skin, the epidermis is more readily

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