Characterization of cultured nail matrix cells

[Hand and endocrine diseases]

The whole of hormones likely influence state of hands, modifying colouring and trophicity of the skin and having influence on its muscular, tendineous, osseous, articular components. Thus state of the hands contributes to the recognition of the endocrine diseases: hot and moist hands of the Graves' disease, dry, cold and infiltrated hands in myxoedema, pale and fine hands of hypopituitarism, broad and thick hand of acromegaly, brachymetacarpia in the pseudohypoparathyroidism… Diabetes exposes particularly to tendineous and articular retractions, to whitlows and ungual mycosis.

Nail biology and nail science

The nail plate is the permanent product of the nail matrix. Its normal appearance and growth depend on the integrity of several components: the surrounding tissues or perionychium and the bony phalanx that are contributing to the nail apparatus or nail unit. The nail is inserted proximally in an invagination practically parallel to the upper surface of the skin and laterally in the lateral nail grooves. This pocket-like invagination has a roof, the proximal nail fold and a floor, the matrix from which the nail is derived. The germinal matrix forms the bulk of the nail plate. The proximal element forms the superficial third of the nail whereas the distal element provides its inferior two-thirds. The ventral surface of the proximal nail fold adheres closely to the nail for a short distance and forms a gradually desquamating tissue, the cuticle, made of the stratum corneum of both the dorsal and the ventral side of the proximal nail fold. The cuticle seals and therefore protects the ungual cul-de-sac. The nail plate is bordered by the proximal nail fold which is continuous with the similarly structured lateral nail fold on each side. The nail bed extends from the lunula to the hyponychium. It presents with parallel longitudinal rete ridges. This area, by contrast to the matrix has a firm attachment to the nail plate and nail avulsion produces a denudation of the nail bed. Colourless, but translucent, the highly vascular connective tissue containing glomus organs transmits a pink colour through the nail. Among its multiple functions, the nail provides counterpressure to the pulp that is essential to the tactile sensation involving the fingers and to the prevention of the hypertrophy of the distal wall tissue, produced after nail loss of the great toe nail.

Onycholysis Associated with Capecitabine in Patients with Breast Cancer

Background:

Onycholysis, which is separation of the nail plate from the nail bed at its distal and lateral attachments, can cause pain and impair function and is a well-known side effect of traditional chemotherapeutic agents.

Objectives:

We present two cases of onycholysis associated with capecitabine in women with advanced breast cancer, who were initially referred for evaluation of onychomycosis and review the literature on capecitabine.

Conclusion:

Owing to the increased frequency of use of capecitabine for different cancers, physicians should be aware of this side effect.

Immunology of the Human Nail Apparatus: The Nail Matrix Is a Site of Relative Immune Privilege

The nail apparatus is constantly exposed to environmental damage. It requires effective immune responses to combat infection, while avoiding the loss of nail production and regeneration by autoaggressive immunity. By immunohistology, we define here previously unknown characteristics of the normal human nail immune system (NIS). Compared with other regions of nail epithelium, human leukocyte antigen (HLA)-A/B/C expression is prominently down regulated on both keratinocytes and melanocytes of the proximal nail matrix (PNM), whereas HLA-G(+) is upregulated here. Together with the expression of macrophage migration inhibitory factor in PNM, this may serve to inhibit an natural killer (NK) cell attack on major histocompatibility complex (MHC) class Ia-negative PNM. PNM also displays strong immunoreactivity for potent, locally generated immunosuppressants such as transforming growth factor-beta1, alpha-melanocyte stimulating hormone, insulin-like growth factor-1, and adrenocorticotropic hormone, exhibits unusually few CD1a(+), CD4(+), or CD8(+), NK, and mast cells. Finally, MHC class II and CD 209 expression on CD1a(+) cells in and around the PNM is reduced, indicating diminished antigen-presenting capacity. Thus, the NIS strikingly differs from the skin immune system, but shows intriguing similarities to the hair follicle immune system, including the establishment of an area of relative immune privilege in the PNM. This nail immune privilege may offer a relative safeguard against autoimmunity. But, the localized intraepithelial defect of innate and adaptive immunity in the PNM revealed here also may impede effective anti-infection defense.

Serial cultivation of human nail matrix cells under serum-free conditions

We have established serial cultures of human nail matrix cells (NMCs) under serum-free conditions. We cultured NMCs using two different methods depending upon the volume of nail matrix obtained. When a sufficient amount of nail matrix was obtained, they were minced and treated with 0.25% trypsin and 0.03% EDTA. The NMCs were transferred directly as a dispersed cell culture into KGM medium. Because a sufficient amount of matrix was rarely obtained, we developed a method by which NMCs were cultured primarily as implanted small matrices in Eagle's MEM (high Ca+ medium) supplemented with 15% fetal bovine serum for the first 4 to 5 days; during this time, the NMCs expanded from the matrices and formed colonies around them. NMCs then were cultured with KGM. In both methods, KGM medium supported the growth of NMCs without a biological feeder layer. These cells could be cultivated serially for at least seven passages. Half of the cells were positively stained with a monoclonal antibody against hair (hard) keratin which is expressed in nail matrix in vivo, indicating that the cells originated from the nail matrix. These methods will now permit investigations of nail matrix cells that previously were unfeasible because of the relative lack of cells and difficulties with propagation.