Scientists have discovered a group of stem cells in mice that can repopulate and maintain all cell types of the hair follicle, reports a study online in Nature Genetics. This work reverses previously held assumptions about the identity of hair follicle stem cells.
Mouse hair follicle stem cells have been thought to reside in the 'bulge' region of the hair follicle, and a group of non-dividing cells known as 'label retaining cells' have been proposed as the key contributors to hair follicle growth.
Rune Toftgard and colleagues previously showed that a group of cells in the intestine and colon that express the protein Lgr5 have stem cell properties in those tissues. They now report that Lgr5-expressing cells exist in mouse hair follicles, and that such cells proliferate during hair follicle growth. Isolated Lgr5-expressing cells can then regenerate complete hair follicles when transplanted onto the backs of nude mice.
The authors suggest that the label retaining cells may serve as a reserve stem cell population activated after there has been tissue damage. During normal conditions, however, a dividing cell population expressing Lgr5 maintains the hair follicle through its normal cycle of growth and death.
Rune Toftgard (Karolinska Institute, Huddinge, Sweden)
Abstract available online.
(C) Nature Genetics press release.
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