Epidermal sheets spread centrifugally postinjury from the hair follicle infundibulum to reepithelialize the wound bed. Healing progresses faster in skin areas rich in terminal hair follicles. These observations are consistent with the role of the hair follicle as a major reservoir for progenitor cells. To evaluate the feasibility and potential healing capacity of autologous scalp follicular grafts transplanted into the wound bed of chronic leg ulcers, 10 patients with ulcers of an average 36.8 cm(2) size and a 10.5-year duration were included in this pilot study. Within each ulcer we randomly assigned a 2 × 2 cm "experimental" square to receive 20 hair grafts and a nongrafted "control" square of equal size. The procedure seemed to be safe, although major unrelated complications occurred in two patients. At the 18-week end point, we observed a 27.1% ulcer area reduction in the experimental square as compared with 6.5% in the control square (p = 0.046) with a maximum 33.5% vs. 9.7% reduction at week 4 (p = 0.007). Histological analyses showed enhanced epithelialization, neovascularization, and dermal reorganization. We conclude that terminal hair follicle grafting into wound beds is feasible in an outpatient setting and represents a promising therapeutic alternative for nonhealing chronic leg ulcers.
The pilosebaceous unit (PSU) and the eccrine sweat gland (ESG) are classically described as completely independent skin appendages. However, careful inspection of scalp follicular units reveals that the secretory segment of the ESG spatially approximates the hair follicle in a position below the sebaceous gland and the insertion of the arrector pili muscle. Therefore, we propose here that, contrary to conventional wisdom, the PSU and the ESG should not be viewed in isolation, and may form instead, along with the arrector pili muscle and the apocrine gland (where present),one functional unit. For this, we suggest the more inclusive term of 'Hair Cluster' (HC). If confirmed, e.g. by 3D imaging techniques, the novel concept of a functional HC, whose individual components may communicate via secreted molecules and may share selected progenitor cell populations for HC repair/ regeneration, has major physiological and pathological implications, which are briefly discussed.
Background. Expression of human CD133 (human prominin-1) in cancer cells has been postulated to be a marker of stemness and is considered as a putative marker of cancer stem cells (CSCs). We designed a study to describe the expression pattern of CD133 in normal skin and in epithelial cutaneous neoplasms. Methods. The CD133 immunohistochemical expression of forty-three eccrine and apocrine tumors was compared to that observed in other epithelial tumors of the skin. In addition, flow cytometry was used to detect the CD133 expression of four epithelial skin neoplasms, including one porocarcinoma. Results. CD133 immunoreactivity at the apical or at the apicolateral surface of cells forming glandular structures was observed. Cells from solid areas of benign or malignant tumors were not stained. The porocarcinoma derived culture cells showed a 22% of CD133 positive cells using flow cytometry, while squamous cell carcinoma cultures contained less than 0.1%. Conclusions. These observations indicate that CD133 is a specific marker of glandular differentiation that could be included in the diagnostic panel of cutaneous tumors with possible eccrine or apocrine differentiation. However, the use of CD133 expression as a marker of CSCs should be interpreted with caution in experiments of skin.
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