No description available.

No description available.

No description available.

Neuronal models for Alzheimer's disease research frequently have limitations as a result of their nonhuman origin and/or transformed state. Here we examined the potential of readily accessible neural crest-derived human epidermal melanocytes isolated from elderly individuals as a model system for Alzheimer's disease research. The amyloidogenic isoforms of amyloid precursor protein (APP; isoforms APP751/770) and amyloid beta (A¿)1¿40 were detected in epidermal melanocytes using immunocytochemistry and western blotting. Incubation of epidermal melanocytes with aggregated A¿1¿40 peptide caused a concentration-dependent reduction in cell viability, whereas age-matched dermal fibroblasts remained unaffected. These findings suggest that epidermal melanocytes from elderly donors are capable of amyloidogenesis and are sensitive to A¿1¿40 cytotoxicity. Thus, these cells may provide a readily accessible human cell model for Alzheimer's disease research.

No / Human skin is a local source of corticotropin-releasing hormone (CRH) and expresses CRH and CRH receptors (CRH-R) at mRNA and protein levels. Epidermal melanocytes respond to CRH by induction of cAMP with up-regulation of pro-opiomelanocortin gene expression and subsequent production of adrenocorticotropin hormone. However, the role of CRH/CRH-R in melanocyte biology is complicated by the significant heterogeneity of cutaneous melanocyte subpopulations, from continuously active and UV-responsive melanocytes in epidermis to UV nonresponsive, hair growth cycle-coupled melanogenesis in hair follicles. In the present study we report that normal human scalp hair follicle melanocytes express CRH at the mRNA level. Furthermore, CRH, urocortin and CRH-R 1 and 2 were differentially expressed in follicular melanocytes, fibroblasts, and keratinocytes depending on anatomic location and differentiation status in situ and in vitro. Stimulation of follicular melanocytes with CRH and CRH peptides, modified for selectivity for CRH-R1 and/or CRH-R2, variably induced cell melanogenesis, dendricity, and proliferation. CRH-peptides also stimulated the expression and activity of Tyrosinase, and expression of Tyrosinase-related protein-1 and-2. However, a modified urocortin peptide highly selective for CRH-R2 down-regulated melanocyte differentiation phenotype. This study indicates that CRH peptides can differentially influence hair follicle melanocyte behavior not only via CRH-R1 signaling but also by complex cross-talk between CRH-R1 and CRH-R2.¿Kauser, S., Slominski, A., Wei, E. T., Tobin, D. J. Modulation of the human hair follicle pigmentary unit by corticotropin-releasing hormone and urocortin peptides.

No / Skin pigmentation is a multistep process of melanin synthesis by melanocytes, its transfer to recipient keratinocytes and its degradation. As dyspigmentation is a prominent marker of skin ageing, novel effective agents that modulate pigmentation safely are being sought for both clinical and cosmetic use. Here, a number of plant extracts were examined for their effect on melanogenesis (by melanin assay and Western blotting) and melanin transfer (by confocal immunomicroscopy of gp100-positive melanin granules in cocultures and by SEM analysis of filopodia), in human melanocytes and in cocultures with phototype-matched normal adult epidermal keratinocytes. Mulberry, Kiwi and Sophora extracts were assessed against isobutylmethylxanthine, hydroquinone, vitamin C and niacinamide. Compared with unstimulated control, all extracts significantly reduced melanogenesis in human melanoma cells and normal adult epidermal melanocytes. These extracts also reduced melanin transfer and reduced filopodia expression on melanocytes, similar to hydroquinone and niacinamide, indicating their effectiveness as multimode pigmentation actives.

No / The development of hair follicle organ culture techniques is a significant milestone in cutaneous biology research. The hair follicle, or more accurately the "pilo-sebaceous unit", encapsulates all the important physiologic processes found in the human body; controlled cell growth/death, interactions between cells of different histologic type, cell differentiation and migration, and hormone responsitivity to name a few. Thus, the value of the hair follicle as a model for biological scientific research goes way beyond its scope for cutaneous biology or dermatology alone. Indeed, the recent and dramatic upturn in interest in hair follicle biology has focused principally on the pursuit of two of biology's holy grails; post-embryonic morphogenesis and control of cyclical tissue activity. The hair follicle organ culture model, pioneered by Philpott and colleagues, ushered in an exceptionally accessible way to assess how cells of epithelial (e.g., keratinocytes), mesenchymal (e.g., fibroblasts), and neuroectodermal (e.g., melanocytes) origin interact in a three-dimensional manner. Moreover, this assay system allows us to assess how various natural and pharmacologic agents affect complex tissues for growth modulation. In this article, I focus on the culture of the human hair follicle mini-organ, discussing both the practical issues involved and some possible research applications of this assay.

No / Although we have made significant progress in understanding the regulation of the UVR-exposed epidermal-melanin unit, we know relatively little about how human hair follicle pigmentation is regulated. Progress has been hampered by gaps in our knowledge of the hair growth cycle’s controls, to which hair pigmentation appears tightly coupled. However, pigment cell researchers may have overly focused on the follicular melanocytes of the nocturnal and UVR-shy mouse as a proxy for human epidermal melanocytes. Here, I emphasize the epidermis-follicular melanocyte pluralism of human skin, as research models for vitiligo, alopecia areata and melanoma, personal care/cosmetics innovation. Further motivation could be in finding answers to why hair follicle and epidermal pigmentary units remain broadly distinct? Why melanomas tend to originate from epidermal rather than follicular melanocytes? Why multiple follicular melanocyte sub-populations exist? Why follicular melanocytes are more sensitive to aging influences? In this perspective, I attempt to raise the status of the human hair follicle melanocyte and highlight some species-specific issues involved which the general reader of the pigmentation literature (with its substantial mouse-based data) may not fully appreciate.

A legislação brasileira para cosméticos exige que os apelos mercadológicos desses produtos sejam comprovados. Os testes in vivo utilizando animais para avaliação desta categoria de produtos ou os princípios ativos nela contidos são, atualmente, bastante criticados. O presente trabalho teve como objetivo desenvolver um modelo de cultura de pele humana e avaliar a viabilidade dos melanócitos durante o período de 7 dias. A manutenção do tecido foi avaliada pela observação microscópica após coloração com HE e Masson, os melanócitos ativos pela reação de DOPA e a melanina pela coloração Fontana-Masson. Fragmentos de pele com 2mm2 mantidos em meio de Leibovitz à temperatura ambiente e atmosfera com 95% de ar e 5% de CO2, sofreram menos alterações morfológicas comparados aos mantidos em DMEM à temperatura de 37°C, 5% de CO2, 40% de O2 e 55% de N2. Fragmentos com 20mm2 mantidos em Leibovitz apresentaram alterações semelhantes aos de 2mm2. Células em divisão foram observadas em amostras de pele mantidas em Leibovitz enriquecido com SFB e ácido retinóico. A presença de melanina foi verificada durante todo o período de cultura, bem como a dos melanócitos, que se mostraram DOPA reativos. A radiação UVA/UVB, empregada com a finalidade de verificar se os melanócitos sofriam alguma alteração na atividade e morfologia, não provocou qualquer mudança nestas células, por outro lado induziu uma redistribuição da melanina nos queratinócitos dos fragmentos irradiados. Os resultados obtidos mostraram que é possível manter pele humana em cultura por 7dias, bem como a viabilidade dos melanócitos e sugere ser possível a aplicação do modelo estudado em futuros ensaios de eficácia e segurança de produtos tópicos. / The Brazilian law for cosmetics demands that the marketing of these products should be proofed. The tests in vivo utilizing animals for evaluation of this category of products or the active components in it, are very criticized nowadays. The present work had as an objective to develop a model of culture of human skin, and evaluate the viability of the melanocytes during a period of 7 days. The maintenance of the tissue was evaluated by the microscopic observation after coloring with HE and Masson, the active melanocytes by the DOPA reaction and the melanin by coloring of Fontana-Masson. Fragments of skin with 2mm2 kept in Leibovitz at room temperature and atmosphere with 95 % of air and 5 % of CO2, presented less morphologic alterations than the ones kept in DMEM at the temperature of 37, 5% of CO2, 40% of O2 and 55% of N2. Fragments with 20mm2 kept in Leibovitz presented similar alterations to the 2mm2. Mitotic cells were observed in samples of skin kept in enriched Leibovitz with FBS and retinoic acid. The presence of melanin was verified through all of the period of culture as well as the melanocytes that were DOPA-reactive. The radiation UVA/UVB, used with the aim of verifying if the melanocytes presented any alteration in the activity and morphology, didn\'t provoke any changes in the cells, on the other hand it induced a redistribution of the melanin in the keratinocytes of the irradiated fragments. The results obtained showed that it is possible to keep the human skin in culture for 7 days as well as the viability of melanocytes, and suggests the possibility of application of the studied model in future research on the efficacy and the safety of topic products.

Observações feitas pelo próprio autor sugerem potencial ação do Líquido da Castanha de Caju (LCC) na pigmentação da pele, ação esta semelhante a da hidroquinona. O LCC é um líquido contido na casca da castanha de caju, possui característica de resina líquida, bastante viscosa e de odor forte, sua coloração varia de marrom claro, escuro a preto, dependendo do método de extração utilizado, podendo ser denominado de Natural ou Técnico. Este estudo propôs cultivar melanócitos e queratinócitos em cocultura e posteriormente tratálos com LCC. A L-DOPA, agente estimulador da melanogênese, via da produção de melanina, responsável pela pigmentação da pele, foi utilizada na cocultura para avaliar a ação do LCC. A hidroquinona, conhecido inibidor desta via, foi utilizada na cocultura como controle positivo para o LCC, visto que este poderia apresentar ação semelhante a da hidroquinona. Para a utilização do LCC na cocultura, testes de solubilidade do mesmo para posterior dispersão no meio de cultura, foram necessários, bem como a identificação de seu potencial cito e fototóxico in vitro. Para a realização do teste de fototoxicidade foi construída uma câmara específica, atendendo as normas exigidas pelos guias ©ECVAM DB-ALM: INVITTOX protocol e OECD TG-432, sendo esta qualificada por método validado. Os testes realizados com o LCC (natural e técnico) indicaram potencial ação destes na pigmentação da pele, estimulando a proliferação de melanócitos em cocultura. Este perfil apresentado, pelos extratos de LCC, é contrário ao da hidroquinona, e ao esperado inicialmente, sendo necessário aprofundar estes estudos. No entanto, estes resultados são promissores, sugerindo a descoberta de um novo tratamento para hipocromias. / Observations, made by the author, suggest potential action of Cashew Nut Shell Liquid (CNSL) in skin pigmentation, action similar to hydroquinone. The CNSL is a liquid contained inside the shell of the cashew nut, it has features of liquid resin, quite viscous and strong smell. Its color varies from clear or dark brown, to black, depending on the extraction method used, which may be called Natural or Technical. This study aimed to cultivate melanocytes and keratinocytes in co-culture and thus treat them with CNSL. The L-DOPA, stimulating agent of melanogenesis, melanin production pathway, responsible for skin pigmentation, was used to assess the CNSL action in the co-culture. Hydroquinone, known inhibitor of this pathway, was used as positive control for CNSL in the co-culture, since this could provide a similar action to hydroquinone. For use of CNSL in the co-culture, solubility tests, for subsequent dispersion in the culture medium, were necessary, as well as the identification of its cytototoxic and phototoxic potential in vitro. To achievement of the phototoxicity tests a specific chamber was built according to the standards required by the guides ©ECVAM DB-ALM: INVITTOX protocol and OECD TG-432, being qualified by validated method. Tests conducted with the CNSL (natural and technical) indicated their potential actions in skin pigmentation, stimulating the proliferation of melanocytes in co-culture. This behavior presented by the CNSL extracts, is opposite to the hydroquinone, and to the initially expected, being required further studies. However, these results are promising, suggesting the discovery of a new treatment for hypochromia.