Macrophages Contribute to the Cyclic Activation of Adult Hair Follicle Stem Cells

December 2014 in “ PLoS Biology ”

Donatello Castellana, Ralf Paus, Mirna Pérez‐Moreno

macrophages hair follicle stem cells apoptosis Wnt transcription telogen perifollicular macrophages skin epithelial stem cells

Studysummary This study found that macrophages near hair follicles contribute to the activation of skin epithelial stem cells in mice, suggesting a novel role for macrophages in regulating hair growth.

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The study demonstrated that skin-resident macrophages played a role in the activation of hair follicle stem cells during the murine hair cycle by undergoing apoptosis before stem cell activation. This process was associated with changes in gene expression, including Wnt transcription. By inducing macrophage apoptosis in early telogen, researchers identified macrophages as contributors to stem cell activation in vivo. Additionally, inhibiting macrophage-specific Wnt production delayed hair follicle growth, suggesting that perifollicular macrophages provided a novel regulatory cue for the regenerative activity of skin epithelial stem cells. These findings had potential implications for skin repair, inflammatory skin diseases, and cancer.

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