Melanocytes and Langerhans Cells in Aged Versus Young Skin Before and After Transplantation onto Nude Mice

Previous studies have demonstrated decreased numbers of melanocytes and Langerhans cells (LC) in aged skin. In the present study, we employed dopa and indirect immunoperoxidase techniques in epidermal sheets to determine the fate of melanocytes and LC of aged versus young donors after skin transplantations onto nude mice. The detection of positive homologous leucocytic antibody reaction of degeneration (HLA-DR) of LC indicates an age-associated reduction in sun-protected thigh skin in aged versus young subjects (263 ± 63 versus 589.25 ± 142.643, p < 0.001). The mean number of LC four weeks after transplanation remained almost constant. Prior to skin engraftment, a decreased number of melanocytes was found in aged versus young epidermis (160.77 ± 51.7 versus 255.83 ± 81.2, respectively, p < 0.05). A significantly increased number of melanocytes was noted four weeks following engraftment in epidermis from aged (307.44 ± 174, p <0.05) and young human donors (402.16 ± l39,p < 0.02). The marked increase in density of dopa-positive melanocytes following engraftment onto nude mice may indicate the existence of circulating factors in nude mice that perhaps both stimulates and enhances proliferation and activity of these cells

Erythropoietin Improves the Survival of Fat Tissue after Its Transplantation in Nude Mice

Background: Autologous transplanted fat has a high resorption rate, providing a clinical challenge for the means to reduce it. Erythropoietin (EPO) has non-hematopoietic targets, and we hypothesized that EPO may improve long-term fat graft survival because it has both pro-angiogenic and anti-apoptotic properties. We aimed to determine the effect of EPO on the survival of human fat tissue after its transplantation in nude mice. Methodology/Principal Findings: Human fat tissue was injected subcutaneously into immunologically-compromised nude mice, and the grafts were then treated with either 20 IU or 100 IU EPO. At the end of the 15-week study period, the extent of angiogenesis, apoptosis, and histology were assessed in the fat grafts. The results were compared to vascular endothelial growth factor (VEGF)-treated and phosphate-buffered saline (PBS)-treated fat grafts. The weight and volume of the EPOtreated grafts were higher than those of the PBS-treated grafts, whose weights and volumes were not different from those of the VEGF-treated grafts. EPO treatment also increased the expression of angiogenic factors and microvascular density, and reduced inflammation and apoptosis in a dose-dependent manner in the fat grafts. Conclusions/Significance: Our data suggest that stimulation of angiogenesis by a cluster of angiogenic factors and decreased fat cell apoptosis account for potential mechanisms that underlie the improved long-term survival of fa

A new humanized mouse model for alopecia areata.

Although alopecia areata (AA) is not life threatening, it may lead to severe psychological disturbances, reducing the quality of life in all ages. Thus, a new animal model is needed for shedding more light onto the pathogenesis of this cell-mediated, organ-specific autoimmune disease to identify more effective therapeutic strategies. Recently, we succeeded in developing a new humanized mouse model of AA, which includes transplantation of healthy human scalp skin obtained from normal volunteers on to severe-combined immunodeficient mice. This is followed by intradermal injection of either autologous or allogeneic peripheral blood mononuclear cells, which had been cultured with high dose of IL-2 and enriched for natural killer group 2D–positive (NKG2D+) and CD56+ cells. This protocol leads to rapid and predictable development of focal hair loss, with all the characteristic clinical, histological, and immunohistochemical features of AA. This humanized mouse AA model underscores the functional importance of NKG2D+ and CD56+ cells in AA pathogenesis and promises to be instrumental for identifying novel AA treatment strategies

Alopecia Areata

To the Editor: In their review article on alopecia areata, Gilhar et al. (April 19 issue) 1 do not mention psoralen–ultraviolet A (PUVA) photochemotherapy. This was probably because there have been no published controlled studies of this local immunosuppressive treatment for extensive alopecia areata. 2 However, reported response rates are typically as good as those for contact immunotherapy, which is supported by only slightly better evidence, with half-scalp comparative studies confirming an effect. 3 Contact immunotherapy involves the discomfort of a medically induced dermatitis every week; PUVA only rarely causes localized phototoxic responses. In terms of long-term risks, whole-body PUVA treatment increases the . .