First published online February 20, 2008
Journal of Cell Science 121, 501e (2008)
© The Company of Biologists Limited
A new home for epidermal stem cells
Because it is continually renewed, the mammalian epidermis is rich in multipotent stem cells, which can differentiate into the hair-follicle, the sebaceous-gland or the interfollicular-epidermis lineages. In the mouse, a major population of epidermal stem cells – which primarily gives rise to hair follicle cells – resides in the bulge region of the hair follicle, but from where are other differentiated cell types generated? On page 609, David Owens and colleagues identify a likely population of stem cells, which reside in the upper isthmus (UI) of the hair follicle. The authors show that the UI cell population, which expresses 
6 integrin at a low level and does not express CD34 or stem cell antigen-1, can be isolated by flow cytometry. They go on to show that the purified cells cycle actively and are clonogenic. Moreover, the cells differentiate into various epidermal cell types and stimulate hair growth when implanted into the skin of nude mice. Using microarray analysis, the authors demonstrate that UI cells and bulge stem cells have distinct gene-expression profiles. The authors propose, therefore, that the UI cell population constitutes an additional reservoir of stem or progenitor cells within the mouse epidermis.
Related articles in JCS:
- A distinct population of clonogenic and multipotent murine follicular keratinocytes residing in the upper isthmus
- Uffe Birk Jensen, Xiaohong Yan, Charlotte Triel, Seung-Hyun Woo, Rikke Christensen, and David M. Owens
JCS 2008 121: 609-617.
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