The ventral proximal nail fold: stem cell niche of the nail and equivalent to the follicular bulge – a study on developing human skin
Article first published online: 16 JUL 2012
Copyright © 2012 John Wiley & Sons A/S
Journal of Cutaneous Pathology
Volume 39, Issue 9, pages 835–843, September 2012
How to Cite
The ventral proximal nail fold: stem cell niche of the nail and equivalent to the follicular bulge – a study on developing human skin, .
- Issue published online: 21 AUG 2012
- Article first published online: 16 JUL 2012
- Accepted manuscript online: 22 JUN 2012 12:03PM EST
- Manuscript Revised: 17 JUN 2012
- Manuscript Accepted: 17 JUN 2012
- Manuscript Received: 13 MAY 2012
- stem cells
Although the bulge is well characterized as a stem cell niche of the hair follicle, comparatively little is known about the location of stem cells in the nail. Herein, we describe the spatiotemporal expression pattern of six stem cell markers in the developing human nail and compared it with the embryonic and fetal human hair follicle. The areas of proliferative activity were additionally examined using labeling with Ki-67.
We examined immunohistochemically samples from embryonic and fetal human nail, hair and skin for the expression of cytokeratin 15 (CK15, two clones), cytokeratin 19 (CK19), PHLDA1, CD200, nestin and Ki-67 using standard techniques.
CK15 (clone LHK15), CK19 and PHLDA1 are negative in the nail and hair matrix but positive in the ventral proximal nail fold and in the follicular bulge. Over the course of embryogenesis they display a highly specific spatiotemporal expression pattern both in the nail and in the hair follicle.
We propose that at least during embryogenesis the proximal ventral nail fold represents the niche for the nail stem cells. In contrast to animal experiments, autoradiographic pulse-chasing studies cannot be performed in human, and immunohistochemical studies are a valid alternative although they have their limitations. Further studies on adult human nail units are suggested.