Reduced Elastin Fibers and Melanocyte Loss in Vitiliginous Skin Are Restored after Repigmentation by Phototherapy and/or Autologous Minigraft Transplantation.

Vitiligo is a hypopigmentation disease characterized by melanocyte death in the human epidermis. However, the mechanism of vitiligo development and repigmentation is largely unknown. Dermal fiber components might play an important role in vitiligo development and repigmentation. Indeed, our preliminary study demonstrated that elastin fibers were decreased in vitiliginous skin, suggesting that the elastin fiber is one of the factors involved in vitiligo development and repigmentation. To confirm our hypothesis, we investigated whether elastin fibers can be restored after treatment using phototherapy and/or autologous skin transplantation. Punch biopsies from 14 patients of stable nonsegmental vitiligo vulgaris were collected from nonlesional, lesional, and repigmented skin, and processed to dopa and combined dopa-premelanin reactions. Melanocytes positive to the dopa reaction and melanoblasts/melanocytes positive to the combined dopa-premelanin reaction were surveyed. Moreover, elastin fibers were detected by Victoria blue staining. Numerous melanocytes and melanoblasts were observed in the epidermis of repigmented skin after the treatment. Moreover, in the dermis of repigmented skin, elastin fibers were completely recovered or even upregulated. These results suggest that melanocyte loss in the vitiliginous skin, as well as melanocyte differentiation in repigmented skin, may be at least in part regulated by elastin fibers in the dermis.

The human melanocyte and melanoblast populations per unit area of epidermis in the rete ridge are greater than in the inter-rete ridge.

OBJECTIVE: In human skin, melanocytes and melanoblasts are mostly located in the epidermis in addition to hair follicles. In hairy skin such as mouse skin, the inter-follicular epidermis is generally flat. In contrast, in human skin, the epidermis is wavy and possesses well-developed rete ridges. It is not well understood what difference exists in cell function between melanocytes present in the inter-rete ridge and those in the rete ridge. To clarify this problem, we first tried to determine the melanocyte and melanoblast populations per unit area of epidermis both in the rete ridge and inter-rete ridge epidermis. METHODS: Thirty-eight samples from normal skin sites of 28 patients (14 males and 14 females) aged from 5 to 76 years were fixed and processed to dopa and combined dopa-premelanin reactions. The numbers of cells positive to the dopa (melanocytes) and combined dopa-premelanin (melanoblasts and melanocytes) reactions were scored. RESULTS: The average melanocyte population/0.1 mm2 of the inter-rete ridge was 74 cells, whereas that of the rete ridge was 147 cells. Moreover, the average melanoblast population/0.1 mm2 in the inter-rete ridge was 43 cells, whereas that of the rete ridge was 131 cells. The melanoblast population in the rete ridge differed between female and male, but the melanocyte populations in the rete ridge and inter-rete ridge and the melanoblast population in the inter-rete ridge did not differ between female and male. However, no age difference in the melanocyte and melanoblast populations was observed between the rete ridge and inter-rete ridge. CONCLUSION: Human epidermal melanocytes and melanoblasts in the rete ridge exist more numerously than in the inter-rete ridge.

OBJECTIF: dans la peau humaine, les mélanocytes et les mélanoblastes sont principalement situés dans l'épiderme ainsi que dans les follicules pileux. Dans la peau poilue, comme la peau de souris, l'épiderme interfolliculaire est généralement plat. En revanche, dans la peau humaine, l'épiderme a un aspect ondulé et possède des crêtes épidermiques bien développées. On ne comprend pas bien la différence entre la fonction cellulaire des mélanocytes présents dans la crête inter-épidermique et celle des mélanocytes présents dans la crête épidermique. Afin de clarifier ce problème, nous avons d'abord essayé de déterminer les populations mélanocytaires et mélanoblastiques par unité de surface de l'épiderme, à la fois dans l'épiderme de la crête épidermique et dans celui de la crête inter-épidermique. MÉTHODES: trente-huit échantillons provenant de sites cutanés normaux de 28 patients (14 hommes et 14 femmes), âgés de 5 à 76 ans, ont été fixés et traités pour des réactions à la dopa et à l'association dopa-prémélanine. Le nombre de cellules positives aux réactions à la dopa (mélanocytes) et à l'association dopa-prémélanine (mélanoblastes et mélanocytes) a été évalué. RÉSULTATS: la population mélanocytaire moyenne/0,1 mm2 de la crête inter-épidermique était de 74 cellules, alors que celle de la crête épidermique était de 147 cellules. De plus, la population mélanoblastique moyenne/0,1 mm2 de la crête inter-épidermique était de 43 cellules, alors que celle de la crête épidermique était de 131 cellules. La population mélanoblastique dans la crête épidermique était différente entre les femmes et les hommes, mais les populations mélanocytaires dans la crête épidermique et la crête inter-épidermique, ainsi que la population mélanoblastique dans la crête inter-épidermique, n'étaient pas différentes entre les femmes et les hommes. Cependant, aucune différence liée à l'âge n'a été observée entre la crête épidermique et la crête inter-épidermique dans les populations mélanocytaires et mélanoblastiques. CONCLUSION: chez l'homme, les mélanocytes et les mélanoblastes épidermiques sont plus nombreux dans la crête épidermique que dans la crête inter-épidermique.

Histochemical study of the distribution of epidermal melanoblasts and melanocytes in Asian human skin.

INTRODUCTION: The classical study revealed the melanocyte density in the epidermis of many skin sites of humans. However, these data were obtained by counting melanocytes using dihydroxyphenylalanine (dopa)-treated epidermal sheets. Since rete ridges are developed well in human epidermis, there is a concern about the accuracy of these data. The accurate counting of the melanocyte density in the epidermis including the rete ridges should be performed using histological sections after the dopa treatment. Moreover, it is not known well how many melanoblasts are present in Asian epidermis. The aim of this study was to count the accurate number of melanocytes and melanoblasts. METHODS: Normal skin sites of 9- to 77-year-old patients were fixed with buffered formalin and processed to the dopa and combined dopa-premelanin reactions. The numbers of cells positive to the dopa reaction (melanocytes) and to the combined dopa-premelanin reaction (melanoblasts and melanocytes) were scored. RESULTS: In the skin of arms, legs, back, and belly, similar density (approximately 110-120 cells/0.1 mm2 ) of melanocytes was observed, whereas in the skin of scalp, melanocyte density was much lower (approximately 70 cells/0.1 mm2 ). By contrast, the melanoblast density did not differ between skin sites (approximately 100 cells/0.1 mm2 ). CONCLUSIONS: These results suggest that the melanocyte density does not differ between skin sites except the scalp skin, and a certain number of melanoblasts are present in each skin site of Asian. Melanoblasts seem to be required for producing new melanocytes required to maintain epidermal homeostasis.

Activation of melanoblasts and melanocytes after treatment with monochromatic excimer light and narrowband-ultraviolet B of skin of vitiligo patients.

BACKGROUND: Vitiligo is a hypopigmentation disease characterized by achromatic or hypochromatic macules in several sites of human skin. Although monochromatic excimer light (MEL) and narrowband-ultraviolet B (NB-UVB) have recently been used for efficacious treatment of vitiligo, the repigmentation process and role of melanocytes/melanoblasts are not well known. METHODS: White macules of 28 vitiligo patients were repeatedly exposed with MEL/NB-UVB. After the exposures, punch biopsies of the center and edge of the lesional skin in addition to normal skin were fixed and processed to dopa and combined dopa-premelanin reactions. Melanocytes positive to the dopa reaction and melanoblasts/melanocytes positive to the combined dopa-premelanin reaction were surveyed. RESULTS: Two repigmentation patterns were observed; one was "marginal" and the other was "perifollicular." Although the frequency of the former pattern was much lower than that of the latter pattern, no differences were observed in average percentage of repigmentation and the number of melanocytes and melanoblasts observed at the center and edge of the lesional epidermis. CONCLUSIONS: These results suggest that exposures with MEL/NB-UVB induce the marginal or perifollicular repigmentation pattern in the white macules, though the two patterns produce no differences in the distribution and density of melanoblasts/melanocytes in the lesional epidermis.