Exp Dermatol. 2019 Mar 28. doi: 10.1111/exd.13924. [Epub ahead of print]

Injury modifies the fate of hair follicle dermal stem cell progeny in a hair-cycle dependent manner.

Abbasi S¹, Biernaskie J^1,2,3.

Abstract

The dermal papilla (DP) is one of two principal mesenchymal compartments of the hair follicle (HF). We previously reported that a population of HF dermal stem cells (hfDSCs) function to regenerate the dermal sheath (DS), but intriguingly also contribute new cells to the adult DP at the onset of anagen hair growth to maintain normal cycling of HFs and support the production of large hair fibers. Here, we asked whether injury altered the behavior of hfDSCs and their progeny in order to support wound-induced hair growth (WIHG) and if the response was modulated by hair cycle stage. αSMACreER^{T 2} :ROSA^YFP mice received tamoxifen to label the DS, including hfDSCs. Full-thickness excisions were made on the dorsal skin during various stages of the hair cycle. The skin was harvested at the subsequent anagen. Interestingly, there was an increase in the magnitude of recruitment of hfDSC progeny into the DP after injury compared to follicles entering natural second anagen. This bias toward a DP fate only occurred when a wound was induced during certain stages of the HC. In summary, injury modifies the fate of hfDSCs progeny, biasing them toward recruitment into the DP, with the hair cycle stage also influencing this response. This article is protected by copyright. All rights reserved.