Stem cells in nail unit of mammalians

Abstract

The review analyzes the current state of experimental studies on the ability to obtain and cultivate stem cells from the nail organ and their possible involvement in the regeneration of a limb. It has been known that the nail unit consists of a pool of undifferentiated cells which provide sustained growth and nail repair throughout life. But, nowadays the issue of stem cell niche localization in the nail organ remains unresolved. Also, researchers demonstrated involvement of these cells in the restoration of amputated limbs, in particular, through activation of certain signaling pathways (Wnt, BMP, Notch), and epithelial-mesenchymal interactions, but the detailed mechanism of this process is poorly understood. It is supposed that the nail organ has two sources of undifferentiated cells of different origin: the proximal nail fold and the dorsal part of the nail matrix (K15+, K19+, PHLDA1+); and onychodermis (CD10+, CD34–). However, these markers are not generally accepted, so the search for markers combinations for exhaustive and complete characterization of stem cells from the nail organ continues.

The Potential of Nail Mini-Organ Stem Cells in Skin, Nail and Digit Tips Regeneration

“…Moreover, Sellheyer and Nelson’s complementary studies [ 18 ] focused on characterizing a slowly proliferating nail cells population within the NPF. During the embryogenesis, these cells expressed the same markers as the well-known hair follicle stem cells: keratin 15 (K15), keratin 19 (K19) and pleckstrin homology like domain, family A, member 1 protein (PHLDA1) [ 19 ] (Figure 3). Thus, in the beginning, the similarity between both cell types suggested further the existence of LRCs in the nail organ, however, localized rather in the ventral proximal fold instead of the previously proposed nail matrix.…”

Morphological and functional characteristics of cell culture derived from the mouse nail unit

“…The nail organ is a complex structural functional unit [4] located on the dorsal side of the distal phalanx and composed of many types of cells, most of which are of epithelial origin -epitheliocytes (hyponychium, cuticle), keratinocytes (ventral nail matrix), melanocytes, Merkel cells, immune cells (Langerhans cells) [5], onychofibroblasts [6,7], stem cells of the nail [8]. The protective function of the nail organ is ensured by the formation of a highly keratinized nail plate that grows throughout life.…”