Dermatology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA.
Program in Epithelial Biology, Stanford University School of Medicine, Stanford, California, USA.
J Invest Dermatol. 2013 Oct;133(10):2324-2331. doi: 10.1038/jid.2013.167. Epub 2013 Apr 4.
The perivascular microenvironment helps in maintaining stem cells in many tissues. We sought to determine whether there is a perivascular niche for hair follicle stem cells. The association of vessels and follicle progenitor cells began by embryonic day 14.5, when nascent hair placodes had blood vessels approaching them. By birth, a vascular annulus stereotypically surrounded the keratin 15 negative (K15-) stem cells in the upper bulge and remained associated with the K15- upper bulge throughout the hair cycle. The angiogenic factor Egfl6 was expressed by the K15- bulge and was localized adjacent to the vascular annulus, which comprised post-capillary venules. Although denervation altered the phenotype of upper bulge stem cells, the vascular annulus persisted in surgically denervated mouse skin. The importance of the perivascular niche was further suggested by the fact that vascular annuli formed around the upper bulge of de novo-reconstituted hair follicles before their innervation. Together, these findings demonstrate that the upper bulge is associated with a perivascular niche during the establishment and maintenance of this specialized region of hair follicle stem cells.
血管周微环境有助于维持许多组织中的干细胞。我们试图确定毛囊干细胞是否存在血管周龛位。血管与毛囊祖细胞的关联始于胚胎第 14.5 天，此时新生的毛囊有血管接近它们。出生时，血管环典型地围绕着在上部隆起处的角蛋白 15 阴性（K15-）干细胞，并在整个毛发周期中与 K15- 上部隆起保持关联。血管生成因子 Egfl6 由 K15- 隆起表达，并定位于包含后微静脉的血管环附近。尽管去神经支配改变了上部隆起干细胞的表型，但血管环在手术去神经支配的小鼠皮肤中仍然存在。血管周龛位的重要性进一步表明，在新形成的毛囊的上部隆起被神经支配之前，血管环就已经围绕着它们形成了。这些发现共同表明，在上部隆起处形成了一个血管周龛位，以维持毛囊干细胞的这一特定区域。
