Dissecting the bulge in hair regeneration
Peggy Myung, Mayumi Ito
Peggy Myung, Mayumi Ito
Published February 1, 2012
Citation Information: J Clin Invest. 2012;122(2):448-454. https://doi.org/10.1172/JCI57414.
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Review Series

Dissecting the bulge in hair regeneration

Abstract

The adult hair follicle houses stem cells that govern the cyclical growth and differentiation of multiple cell types that collectively produce a pigmented hair. Recent studies have revealed that hair follicle stem cells are heterogeneous and dynamic throughout the hair cycle. Moreover, interactions between heterologous stem cells, including both epithelial and melanocyte stem cells, within the hair follicle are just now being explored. This review will describe how recent findings have expanded our understanding of the development, organization, and regeneration of hair follicle stem cells. At a basic level, this review is intended to help construct a reference point to integrate the surge of studies on the molecular mechanisms that regulate these cells.

Authors

Peggy Myung, Mayumi Ito

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Figure 4

The geography of stem cells within the hair follicle.

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The geography of stem cells within the hair follicle. Several distinct a...
Several distinct and overlapping populations of cells have been identified within the telogen hair follicle. The cells that serve as a reservoir for the anagen hair follicle, including McSCs, reside in the sHG and bulge. The sHG sits above the DP during telogen and expresses specific markers (e.g., P-cadherin), while the cells of the bulge upregulate bulge-specific markers (e.g., CD34, Nfatc1, S100A4). Some markers are expressed in both the sHG and bulge in an overlapping manner (e.g., K15, Lgr5). In the isthmus region (between the bulge and opening of the sebaceous gland into the pilary canal), there are other stem cell populations that maintain the sebaceous gland and/or epidermis. Lgr6 and Lrig1 are expressed in isthmus cells and give rise to the sebaceous gland and epidermis. In adult mouse hair follicles, Blimp1 cells are located near or at the opening of the sebaceous gland to the hair canal and appear to act as unipotent sebaceous gland progenitors.