gms | German Medical Science

Objectives/Interrogation: Perfect reconstruction of impaired limb is the ultimate goal of plastic and reconstructive surgery. Comparing to axolotls who can completely regenerate the whole limb, the regeneration ability in mammals are greatly limited. Fingertip is the only compound tissue which can regenerate in human and mice. Regeneration of mouse digit tip requires nail stem cells and their differentiation, suggesting that the nail organ can provide key factors that stimulate digit regeneration. However, the identity and differentiation of human nail stem cells is largely unknown.

Methods: Discarded human fingertip specimens in plastic surgery of congenital polydactyly were used to obtain the nail organ. Immunohistochemistry was applied to detect specific markers and locate different cell types in the nail organ. Immunofluorescence of single-cell preparations of the nail organ was performed to determine the percentage of specific cell populations.

Results and Conclusions: Epithelial cell markers, KRT14 and KRT17, expressed in human nail fold and along the nail bed. At the nail fold, a small cell population positive for KRT17 expressed Ki67 as well. Immunofluorescence of single cell preparation of the nail fold tissue indicated 5% Ki67/KRT17 double positive cells, suggesting a potential stem cell population. Ki67 positive cells were not present in distal nail bed as indicated by both immunohistochemistry and immunofluorescence of the cell suspensions. In conclusion, we identified a potential human nail stem cell population that located at the nail fold and co-expressed KRT17 and Ki67. Single-cell sequencing of the nail fold tissue could be a ideal method to further delineate the identity and the differentiation process of human nail stem cells.