Nail stem cell discovery could lead to tissue regeneration of severe skin injuries and more

Researchers at University of Southern California have identified a new nail stem cell population, which can self-renew or undergo specialization into different tissues.

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Scientists found these stem cells by attaching visible labels, including fluorescent proteins, to mouse nail cells. In doing so, they detected a yet unreported population of quiescent cells within the basal layer of the nail proximal fold. The cells appear in a ring-like configuration around the nail root, according to the study’s abstract.

While many of the cells divided repeatedly, a few in the nail base’s soft tissue either did not divide or divided slowly. The slow-dividing stem cells, the researchers learned, can perform dual roles. The stem cells normally contribute to the growth of the nails and adjacent skin. But, if the nail is injured or lost, the bone morphogenic protein, or BMP, signals a shift in stem cell function and focus to nail repair, according to a USC press release.

"That was very surprising discovery, since the dual characteristic of these nail stem cells to regenerate both the nail and skin under certain physiological conditions is quite unique and different from other skin stem cells, such as those of the hair follicle or sweat gland," Krzysztof Kobielak, M.D., Ph.D., the study’s principal investigator and assistant professor of pathology at USC, says in a press release.

The question remains about whether or not the right signals or environmental cues could induce these nail stem cells to generate other tissue types.

“Collectively, we demonstrate the plasticity of these stem cells: bifunctional under normal homeostasis, but adaptive in response to wounding. Such principles may exist in the interface between other ectodermal organs and skin,” the authors write.

The study was published online October 2, 2014, in the Proceedings of the National Academy of Sciences.

Leung Y, Kandyba E, Chen YB, Ruffins S, Chuong CM, Kobielak K. Bifunctional ectodermal stem cells around the nail display dual fate homeostasis and adaptive wounding response toward nail regeneration. Proc Natl Acad Sci U S A. 2014 Oct 21; 111(42):15114-9.

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