Bald scalp in men with androgenetic alopecia retains hair follicle stem cells but lacks CD200-rich and CD34-positive hair follicle progenitor cells
Luis A. Garza, … , John W. Tobias, George Cotsarelis
Luis A. Garza, … , John W. Tobias, George Cotsarelis
Published January 4, 2011
Citation Information: J Clin Invest. 2011;121(2):613-622. https://doi.org/10.1172/JCI44478.
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Research Article Dermatology

Bald scalp in men with androgenetic alopecia retains hair follicle stem cells but lacks CD200-rich and CD34-positive hair follicle progenitor cells

Abstract

Androgenetic alopecia (AGA), also known as common baldness, is characterized by a marked decrease in hair follicle size, which could be related to the loss of hair follicle stem or progenitor cells. To test this hypothesis, we analyzed bald and non-bald scalp from AGA individuals for the presence of hair follicle stem and progenitor cells. Cells expressing cytokeratin15 (KRT15), CD200, CD34, and integrin, α6 (ITGA6) were quantitated via flow cytometry. High levels of KRT15 expression correlated with stem cell properties of small cell size and quiescence. These KRT15hi stem cells were maintained in bald scalp samples. However, CD200hiITGA6hi and CD34hi cell populations — which both possessed a progenitor phenotype, in that they localized closely to the stem cell–rich bulge area but were larger and more proliferative than the KRT15hi stem cells — were markedly diminished. In functional assays, analogous CD200hiItga6hi cells from murine hair follicles were multipotent and generated new hair follicles in skin reconstitution assays. These findings support the notion that a defect in conversion of hair follicle stem cells to progenitor cells plays a role in the pathogenesis of AGA.

Authors

Luis A. Garza, Chao-Chun Yang, Tailun Zhao, Hanz B. Blatt, Michelle Lee, Helen He, David C. Stanton, Lee Carrasco, Jeffrey H. Spiegel, John W. Tobias, George Cotsarelis

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Figure 4

CD200hiITGA6hi cells localize to the hair follicle bulge and to the secondary germ.

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CD200hiITGA6hi cells localize to the hair follicle bulge and to the seco...
(A) Gated population of CD200hiITGA6hi used for analysis in B, C, F, and G. (B and C) The majority of CD200+ cells were positive for the bulge markers KRT15 (B) and FST (C). (D–F) Ber-EP4 expression marked the secondary germ (D), and CD200 expression overlapped with Ber-Ep4 by double immunofluorescence (E) and flow cytometry (F). (E) Higher numbers of CD200+ cells were present in the upper (left) than in the lower (right) secondary hair germ. (G) As assessed by qPCR, sorted CD200hiITGA6hi cells were enriched in LGR5, a marker for activated bulge/secondary hair germ cells (n = 3). (H) Consistent with this enrichment, LGR5 expression was markedly reduced in bald scalp, whereas KRT15 was maintained, when tested by qPCR (n = 4). *P < 0.01. Scale bars: 100 μm. Numbers within dot plots indicate percent cells in the respective gate or quadrant.