MicroRNA-370-5p inhibits pigmentation and cell proliferation by downregulating mitogen-activated protein kinase kinase kinase 8 expression in sheep melanocytes

In mammals,microRNAs(miRNAs)play key roles in multiple biological processes by regulating the expression of target genes.Studies have found that the levels of miR-370-5p expression differ significantly in the skins of sheep with different hair colors;however,its function remains unclear.In this study,we investigated the roles of miR-370-5p in sheep melanocytes and found that the overexpression of miR-370-5p significantly inhibited cell proliferation(P<0.01),tyrosinase activity(P=0.001)and significantly reduced(P<0.001)melanin production.Functional prediction revealed that the 3′-untranslated region(UTR)of MAP3K8 has a putative miR-370-5p binding site,and the interaction between these two molecules was confirmed using luciferase reporter assays.In situ hybridization assays revealed that MAP3K8 is expressed in the cytoplasm of melanocytes.The results of quantitative RT-PCR and Western blotting analyses revealed that overexpression of miR-370-5p in melanocytes significantly inhibits(P<0.01)MAP3K8 expression via direct targeting of its 3′UTR.Inhibition of MAP3K8 expression by siRNA-MAP3K8 transfection induced a significant inhibition(P<0.01)of melanocyte proliferation and significant reduction(P<0.001)in melanin production,which is consistent with our observations for miR-370-5p.Target gene rescue experiments indicated that the expression of MAP3K8 in melanocytes co-transfected with miR-370-5p and MAP3K8-cDNA(containing sites for the targeted binding to miR-370-5p)was significantly rescued(P≤0.001),which subsequently promoted significant increases in cell proliferation(P<0.001)and melanin production(P<0.01).Collectively,these findings indicate that miR-370-5p plays a functional role in inhibiting sheep melanocyte proliferation and melanogenesis by downregulating the expression of MAP3K8.

Not Follicular but Dermal Melanocyte Precursors Are Histopathologically Retained in Vitiligo

Although perifollicular repigmentation in the vitiligo lesions is owing to activation of follicular melanocyte stem cells and/or precursor cells followed by supplying matured melanocytes, the underlying mechanism of diffuse repigmentation on the whole vitiligo surface remains still unknown. In addition to the presence of remaining melanocytes, it is conceivable that dermal melanocyte precursor cells contribute to induce diffuse repigmentation after treatment. Therefore, we investigated here whether dermal and follicular melanocyte precursor cells were reduced or not in vitiligo lesions. We performed an immunostaining for Nestin and p75NGFR as dermal melanocyte precursor cells and MITF/Fzd4 as follicular melanocyte precursor cells and compared the positive cells number between lesions and non-lesions (n = 11). Although MITF+/Fzd4+ cells in the hair follicle were significantly decreased in number in the lesions, Nestin+ and p75NGFR+ cells were not. This result indicates that dermal precursor cells could be retained in the vitiligo lesions but be disturbed to differentiate into matured melanocytes.

Direct Transplant of Melanocytes from Normal Donor Area into Vitiligenous Recipient Area by Intralesional Injection of Melanocytes Using Spade Like Needle Technique

Background: Vitiligo is a common autoimmune inflammatory skin disease, where there are different surgical techniques for treatment of stable patches of vitiligo .Objective: To find non-costly, minimally invasive, simple technique by direct melanocytes transplant by spade needle technique in treatment of vitiligo. Patients and Methods: This interventional, therapeutic, comparative study was done in Department of Dermatology, Baghdad Teaching Hospital, Baghdad, Iraq from April 2014-March 2015. Twenty patients with localized, generalized and segmental vitiligo were included. Full history and examination for each patient was done with 4 (20%) males and 16 (80%) females and their ages ranged from 9 - 40 (23.15 ± 11.44) years. Forty one patches in 20 patients treated by spade grafting technique and the donor and recipient sites were demarcated and anesthesia done by xylocaine 2% with adrenalin 1:100,000. Transplantation was started by using disposable needle gauge 18 (the sharp end of needle was cut by a scissor to make it a spade like) with medical syringe 5 ml supplied with normal saline. The micro-pieces were taken from donor site and transplanted directly, easily and rapidly into dermis of recipient site and followed by pushing normal saline and the procedure was repeated to cover all recipient sites with 5 mm distance between injection points. The surface area of the lesions was calculated and the reduction rate was estimated every month till the end of the 4th month period of the treatment. Results: Including 41 patches in 20 patients with the surface area of the patches ranged from 1.5 - 90 cm2 (13.78 ± 17.57) cm2. The mean ±SD of surface area of lesions was decreased from 13.78 ± 17.57 cm2 at baseline visit to 13.61 ± 17.48 cm2 at the second visit (after 2 weeks ) which was statistically significant (p value ≤ 0.001). The mean surface area continued to be reduced till reaching 12.20 ± 15.68 cm2 at the third visit and 12.01 ± 15.55 cm2 at the fourth visit. All were statistically significant when compared to baseline visit. There was reduction in surface area 1.1% at two weeks, 9.93%, and 12.5% at the 2nd, 4th months respectively. Conclusions: Intradermal injection of melanocytes in patients with vitiligo by spade like needle was very quick and simple non-costly technique, and gave 12.5% reduction which could be repeated at different times until satisfactory re-pigmentation of vitiligenous skin is achieved.

Follicle and melanocyte stem cells, and their application in neuroscience A Web of Science-based literature analysis

OBJECTIVE： To identify global research trends of follicle and melanocyte stem cells, and their application in neuroscience. DATA RETRIEVAL： We performed a bibliometric analysis of studies from 2002 to 2011 on follicle and melanocyte stem cells, and their application in neuroscience, which were retrieved from the Web of Science, using the key words follicle stem cell or melanocyte stem cell, and neural, neuro or nerve. SELECTION CRITERIA： Inclusion criteria： （a） peer-reviewed published articles on follicle and melanocyte stem cells, and their application in neuroscience, which were indexed in the Web of Science; （b） original research articles, reviews, meeting abstracts, proceedings papers, book chapters, editorial material, and news items. Exclusion criteria： （a） articles that required manual searching or telephone access; （b） documents that were not published in the public domain; and （c） a number of corrected papers from the total number of articles. MAIN OUTCOME MEASURES： （1） Distribution of publications on follicle and melanocyte stem cells by years, journals, countries, institutions, institutions in China, and most cited papers. （2） Distribution of publications on the application of follicle and melanocyte stem cells in neuroscience by years, journals, countries, institutions, and most cited papers. RESULTS： Of the 348 publications from 2002 to 2011 on follicle and melanocyte stem cells, which were retrieved from the Web of Science, more than half were from American authors and institutes. The most prolific institutions in China for publication of papers on follicle and melanocyte stem cells were the Fourth Military Medical University and Third Military Medical University. The most prolific journals for publication of papers on follicle and melanocyte stem cells were the Journal of Investigative Dermatology, Pigment Cell ＆ Melanoma Research. Of the 63 publications from 2002 to 2011 on the application of follicle and melanocyte stem cells in neuroscience, which were retrieved from the Web of Science, more than half were from American authors and institutes, and no papers were from Chinese authors and institutes. The most prolific journals for publication of papers on the application of follicle and melanocyte stem cells in neuroscience were the Journal of Investigative Dermatology, Pigment Cell ＆ Melanoma Research. CONCLUSION： Based on our analysis of the literature and research trends, we found that follicle stem cells might offer further benefits in neural regenerative medicine.

EFFECTS OF BU GU ZHI(PSORALEA CORYLIFOLIA L) AND BAI ZHI(DAHURIAN ANGELICA ROOT) EXTRACTS ON MELANOCYTE ADHESION AND MIGRATION

Objective To find direct effect of Chinese herbs Bu Gu Zhi (Psoralea corylifolia L) and Bai Zhi (Dahurian angelica root) Extracts on melanocyte adhesion and migration in vitro. Methods Ethanol extracts obtained from two kind of Chinese medicinable herbs were tested. Human melanocytes were obtained from neonatal foreskins and 48-well culture dish covered with fibronectin were used to perform melanocyte adhesion assay; Motility was assessed using the micropore filter method. Results: The extracts of Bu Gu Zhi(Psoralea corylifolia L), Bai Zhi(Dahurian angelica root) obviously showed an effect in increasing of human melanocyte adhesion and migration on fibronectin. Conclusion It is suggested that Buguzhi(Fructus Psoraleae) and Baizhi(Radix Angelicae Dahuricae) might induce melanocyte adhesion and/or migration in the treatment of vitiligo.

Effect of Malytea Scurfpea Fruit on Adhesion and Migration of Melanocyte

Objective: To investigate the effect of Malytea Scurfpea fruit (MSF) on adhesion and migration of melanocyte. Methods: Human epidermal melanocytes were treated with MSF and examined for its adhesion to bovine serum fibronectin-coated culture plate and for its migration into micropore filters, which were then compared with those of untreated control. Results: Compared with the control, MSF treated melanocytes were easier to adhere to the dishes and move into the filters in a dose-dependent manner, but when the dose of MSF was higher than 150 μg/ml, the adhesion and migration could not be significantly increased. And it was noticed that when the concentrations of MSF was 10μg/ml, significant statistical difference did show between the migration of the treated and untreated melanocytes ( P<0.05) though the adhesion was not increased significantly. Conclusion: MSF had the ability to affect melanocyte adhesion and migration. This could explain, in part, the mechanism of MSF in curing vitiligo lesions.

Depigmentory Effects of Keishibukuryogankayokuinin in Human Epidermal Melanocytes

Keishibukuryogankayokuinin (KBY) is a traditional Japanese herbal medicine widely used to treat skin pigmentation. The scientific basis for its use is, however, unclear, and studies evaluating its mechanism and effectiveness are sparse. In this study, we compared the tyrosinase inhibitory effects of KBY and Keishibukuryogan (KB, which has the same composition of KBY, except Coix Seed [CS]) and CS under exposure to UV radiation as well as under non-exposure conditions. Neonatal human epidermal melanocytes obtained from a darkly pigmented donor were used. These cells were cultured in a final concentration of 500 μg/ml or 1000 μg/ml, to which KBY, KB, and CS were added. After incubation for 72 h, cells were stained with Fontana-Masson stain and counted. Tyrosinase activity was measured by its dopa oxidase activity, and tyrosinase expression was estimated using real-time PCR. For UV radiation, cells were exposed to UVB radiation for 90 s per day for 3 days. Under non-exposure conditions, tyrosinase activity significantly increased with both KBY and KB but significantly decreased with CS, regardless of the concentration. In addition, tyrosinase expression significantly decreased but only with KBY at both concentrations. Under UV radiation exposure, tyrosinase activity significantly increased with KBY and KB at both concentrations while tyrosinase expression significantly decreased with KBY and KB;a significant increase was, however, observed with CS at both concentrations. These results suggest that taking KBY after sunburn is effective against skin pigmentation, and the combination of KB and CS is useful for skin depigmentation.

Ultrastructure of Amelanotic Melanocytes from Human Hair Follicles

To investigate the ultra structure of amelanotic melanocytes （AMMC）. Methods： The hair follicles obtained from normal human scalp by 0.50% collagenase type V treatment were washed with 0.1 mol/L phosphate buffer salt （PBS）. Hair-follicle cell suspensions were prepared by trypsin treatment and cultured in melanocyte medium. Remaining keratinocytes were removed by differential trypsinization. 100μg/ml geneticin was used to eliminate the contaminating fibroblasts. At third passage, the cells were trypsinized, and then washed in phosphate-buffered saline and processed for transmission electron microscopy. Results： Under transmission electron microscope, the cultured cells showed round or oval shape, with single large nuclear and the karyotheca were double deck. There were obvious euchromosome within the nucleus, and sparse heterochromosome. There were various organelles in the cytoplasm, including plentiful melanosomes with nearly similar size, mitochondria, rough endoplasmic reticule （RER） and ribosome. The electron density granules in most of the melanosomes disposed along concentric circularities. Golgi apparatus in the cells was inconspicuous. Conclusion： The ultra structure of AMMC from human hair follicles is different from that of epidermal melanocytes, and these characteristics determine the functional immature of AMMC.

THE EFFECT OF Ge-132 ON ULTRASTRUCTURE OF CULTURED MELANOCYTES

Objective To elucidate the effect of Ge 132 on the growth of melanocytes.Methods Melanocyes from epidermis were cultured and purified;the second generation of the cell was used for study;the cells were divided into two groups randomly,to group A, Ge 132 was added to the media at 0.04mg/L;to group B,common culturing method was used without Ge 132.After 5d, the cells were seperated by digestion for study by transmission electronic microscope.Results Compared to group B, the vaculoes of the cells were increased,mitochondria distended, endoplasmic reticulum dilated and the number of melanosome declined in the group A.Conclusion Ge 132 can inhibit the melanocytes growth at a certain concentration and might be used for treating pigmented diseases.

Treatment of Gray Hair in Vitiligo Patients by Direct Melanocytes Transplant Using Needling Micrografting and Dermabrasion Techniques

Background: Melanocytes transplant for treatment of vitiligo is a common therapy using different surgical procedures. But there was no interest in repigmentation of grayness of hair in the treated vitiliginous area. Objective: To do melanocytes transplant from donor area into the recipient vitiliginous area with associated gray hair. Patient and Methods: This is a case interventional study was done in Department of Dermatology/Baghdad Teaching Hospital from February 2011-March 2012. Eleven patients were enrolled in this study, six males and five females with vitiligo in association of gray hair. Their ages ranged from 8 - 35 years with a mean ±SD of 20.90 ± 7.006. Melanocytes transplant in patients with vitiligo using needling micrografting technique for twelve patches and direct melanocytes transplant from normal donor area into vitiliginous recipient area by dermabrasion technique for eleven patches. Dressing was applied and patients were seen every two weeks for the first month and monthly for one year. Results: Repigmentation of the vitiliginous area was started after two weeks and was obvious at one month that progressed over time. The repigmentation of hair appeared usually after few months and was obvious after four months and the repigmentation of gray hair was quicker in patients with micrografting technique than those with dermabrasion technique. The mean rate of repigmentation was 18.3% at six months and 37.5% at twelve months in micrografting technique while the mean rate of repigmentation was 9.15% at six months and 18.55 at twelve months in dermabrasion technique. Conclusions: Direct transplant of melanocytes from normal donor area into recipient vitiliginous area with associated white hair is an effective procedure to induce repigmentation of gray hair.

Direct Melanocytes Transplant from Normal Donor Area into Vitiliginous Recipient Area by Dermabrasion Technique

Background: Vitiligo is an autoimmune pigmentory disorder, that affects all age group that is treated by many medical treatments but some of them might need surgical therapy. Objective: To evaluate the dermabrasion technique in the treatment of vitiligo by direct transfer of melanocytes from the dermabraded normal donor area to the vitiliginous recipient area. Patients and Methods: This is a case interventional study was done in Department of Dermatology/Baghdad Teaching Hospital from February 2011-March 2012. Nine Patients with vitiligo were enrolled in this study with different clinical types of vitiligo including 5 segmental, 2 generalized and 2 localized. The donor and recipient areas were anesthetized at the same time with xylocain alone. Dermabrasion of recipient area was done first by manual abrader and left for few minutes until the oozing was stopped. Then the donor area was similarly dermabraded and the dermabraded tissue including the epidermis and superficial epidermis was immediately transferred into the recipient area and dressing was applied. Removal of the dressing was done after 10 - 14 days from the operative time. Follow up was done every 2 weeks in the first month then monthly for six months to record the result of implantation and repigmentation. Results: The re-pigmentation started one month after the operation as small macules and this increased gradually over time: the mean rate of re-pigmentation was 13% at 2 months, 27.8% at 4 months and 36.78% at 6 months. In addition, sun light exposure was applied to enhance re-pigmentation. The pigmentation was diffuse and not follicular in shape. Conclusion: Direct transfer of melanocytes from normal donor area into vitiliginous recipient area by dermabrasion technique was easy, rapid and non-costly and gave 36.78% mean rate of pigmentation at 6 months follow up and without complications.

In Vitro Evaluation of the Potential Antioxidant of Bidens segetum Mart. ex Colla (Asteraceae) in Melanocyte and Melanoma Cells

Bidens segetum Martius ex Colla known as the “pic&atilde;o do mato”, is an herbaceous plant that occurs in the Cerrado biome of some Brazilian states. Among the species of Bidens, we highlight B. pilosa known as “pic&atilde;o preto”, of which several activities are reported as antioxidant and antibacterial. Ethanolic extract from Bidens segetum (EEBs) showed an-tioxidant potential when analyzed by free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and antifungal activity against Cladosporium cladosporiodes and C. sphareospermum fungi. PFFR3.3 subfraction from EEBs has 81.5% of 5-O caffeoylquinic acid (5-CQA) and potential antioxidant (DPPH). However, PFFR3.3 did not decrease superoxide anion in metastatic melanoma cells by dihydroeth-idium assay (DHE). PP4 subfraction is a mixture of polyacetylenes that has antifungal (Cladosporium) and antioxidant activity, since reduced superoxide anion amount in melanoma cells after 5 min of treatment. However, no dose-response and time-response curve were observed, not even with the authentic standard (5-CQA). Complementary chemical studies will be performed to confirm the polyacetylenes and 5-CQA structures present in the EEBs from B. segetum and new methodologies should be performed to confirm the antioxidant activity of these com-pounds and the effects on melanocytes and melanomas.

SFRP5 inhibits melanin synthesis of melanocytes in vitiligo by suppressing the Wnt/b-catenin signaling

Secreted frizzled-related protein 5(SFRP5)plays a pivotal role in regulating the development of many tissues and organs,however,as an inhibitor of Wnt signaling,the role of SFRP5 in vitiligo remains unknown.Hence,we speculated that SFRP5 might be associated with melanogenesis in melanocytes by regulating Wnt signaling in vitiligo.In this study,we found that SFRP5 was overexpressed in the skin lesions of patients with vitiligo.Compared with that in normal epidermal melanocytes(PIG1),the expression of SFRP5 was increased in vitiligo melanocytes(PIG3V).To investigate the effect of SFRP5 on melanin synthesis,PIG1 cells were infected with recombinant SFRP5 adenovirus(AdSFRP5),and PIG3V cells were infected with recombinant siSFRP5 adenovirus(AdsiSFRP5).The results showed that SFRP5 overexpression inhibited melanin synthesis in PIG1 cells through downregulation of microphthalmia-associated transcription factor(MITF)and its target proteins via suppression of the Wnt/b-catenin signaling pathway.Accordingly,SFRP5 silencing increased melanin synthesis and activated the Wnt signaling pathway in PIG3V cells.Moreover,SFRP5 overexpression also downregulated the transcriptional activity of T cell factor/lymphoid enhancer factor(TCF/LEF)in PIG1 cells.Furthermore,this inhibitory effect of SFRP5 on melanin synthesis was reversed by treatment with the b-catenin agonist,SKL2001.The inhibitory action of SFRP5 in pigmentation was further confirmed in vivo using a nude mouse model.Hence,our results indicate that SFRP5 can inhibit melanogenesis in melanocytes.Additionally,our findings showed that SFRP5 plays a vital role in the development of vitiligo,and thus may serve as a potential therapeutic target for vitiligo.

Prostaglandin induces the expression of matrix metalloproteinase-1 in ciliary melanocytes

Background Latanoprost, a prostaglandin F2α analog, has been shown to be an effective intraocular pressure lowering agent which acts by inducing ciliary muscle cells to synthesise matrix metalloproteinases. However, the response of ciliary melanocytes to latanoprost has never been reported. This research has investigated the ability of latanoprost to induce matrix metalloproteinase-1 expression in human ciliary melanocytes, and thereby advance the understanding of the mechanism of PGF2α in decreasing intraocular pressure. Methods In vitro human ciliary melanocytes were treated for 48 hours with five different concentrations of latanoprost （100, 150, 200, 500, and 1000 nmol/L）. Ciliary melanocytes treated with 0.01% ethanol （vehicle） were used as a control. The expression of matrix metalloproteinase-1 in ciliary melanocytes was determined by Western blotting and immunofluorescent staining. Results Western blotting showed that the expression of matrix metalloproteinase-1 in ciliary melanocytes was induced by latanoprost, and the level of expression was dependent on the concentration of latanoprost in the culture medium. Immunofluorescent staining showed that matrix metalloproteinase-1 was confined to the ciliary melanocyte cytoplasm. Conclusions Latanoprost induced the expression of matrix metalloproteinase-1 in human ciliary melanocytes in a dose-dependent manner. Ciliary melanocytes, as well as ciliary muscle cells, may also play an important role in uveoscleral outflow modulation.

Effect of Q-switched Alexandrite laser irradiation on epidermal melanocytes in treatment of Nevus of Ota

To investigate injury to epidermal melanocyte by Q-switched Alexandrite laser Methods Multiple biopsies were performed on 5 patients with nevus of Ota from before irradiation to 1 year after irradiation Fourteen specimens were obtained for light microscopy, and 17 for transmission electron microscopy Results Melanosomes in epidermal melanocytes were both smaller in size and fewer in number than those in dermal melanocytes Immediately after irradiation, focal extracellular vacuoles of the basal layer could be observed under light microscopy Most epidermal melanocytes underwent mild or moderate injury in the form of vacuolated melanosomes, swollen mitochondria, dilation of endoplasmic reticulum, and expansion of extracellular space, retaining intact cell membranes Normal structures were restored 5 months to 1 year after irradiation, with no depigmentation or hyperpigmentation as seen by light microscopy Conclusion Injury of melanosomes in epidermal melanocytes is reversible

Paraneoplastic retinopathies: an update on pathogenesis, diagnosis and management

The paraneoplastic retinopathies are a heterogeneous group of disorders with significant visual consequences occuring in the setting of a systemic malignancy.These conditions may be characterized by the presence of antiretinal antibodies and may predate or follow the diagnosis of an underlying malignancy.Herein I review the clinical findings,pathophysiology,laboratory testing and management of the paraneoplastic retinopathies:cancer-associated retinopathy(CAR),melanoma-associated retinopathy(MAR),bilateral diffuse uveal melanocytic proliferation(BDUMP)and paraneoplastic vitelliform maculopathy(PVM).The pathophysiology of the paraneoplastic retinopathies varies from molecular mimicry resulting in anti-retinal antibody production(CAR,MAR)to relases of soluble factors either by the primary tumor(BDUMP)and/or immune system in response to the primary tumor(PVM)which result in retinal and/or retinal pigment epithelium dysfunction.For each condition,structural and functional multimodal retinal testing can be helpful in establishing the diagnosis.Treatment for the paraneoplastic retinopathies involves a combination of treating the underlying malignancy plus additional local and/or systemic immunosuppressive agents though no systemic therapeutic protocols exist.Despite these interventions,the retinopathy may be progressive or the retinopathy may be a harbinger of poor survival.Nevertheless,prompt diagnosis may help identify an underlying malignancy earlier and may thus improve cancer-related survival.

Role of gap junctions between keratinocyte and melanocyte in melanogenesis

The process ofmelanogenesis in melanocytes and the transport of melanin in the form ofmelanosomes to the neighboring keratinocytes are the key steps in human skin pigmentation. Keratinocytes and melanocytes interact in intricate manner to maintain the homeostasis. The present study was designed to understand the role of cell-cell interaction through the gap junctions between melanocytes and keratinocytes on melanogenesis. We show that, inhibition of the gap junctional activity between human keratinocytes and melanocytes in a coculture system using gap junction blocker lowers the expression of key regulatory genes of melanogenesis such as tyrosinase and microphthalmia- associated transcription factor （MITF）. This was followed by concurrent decrease in tyrosinase protein levels and activity. Our results show the preliminary evidence for the regulation of melanogenesis in melanocytes through direct gap junctional communication by keratinocytes. Deciphering the mechanism and factors involved in the process would uncover the significance of gap junctions in melanogenesis.

THE RECOGNITION OF UV-IRRADITION MELANOCYTE WITH HMB-45 MONOCLONAL ANTIBODY

Monnclonal antibody HMB-45 was previously thought to be melanoma specific antibody and was taken recently as a marker for melanocyte proliferation or activation. A single UV-irradiation system which may induce a functional activity change in melanocytes was used to test the irradiated epidermal melanocyte for expression of HMB-45.Melanocytes, in the epidermis of the biopsies taken 7 days after a single UV exposure, showed markedly stained HMB-45,accompanied by morphological changes such as enlarged size,rich cytoplasma and elongated dendrites. We conclude that since morphological changes in irradiated melanocytes may be interpreted as signs of functional activity changes, melanocytes are exposed to sthnulatory factors induced by UV light and get into a functional activating state to produce melanosome and HMB-45 antigen. Besides, the presence of HMB-45 in a single UV exposed epidermal melanocyte may support the hypothesis that its expression is inducible and is closely related to the functional activity

Effect of Q-switched alexandrite laser irradiation on dermal melanocytes of nevus of Ota

OBJECTIVE: To investigate the effect of Q-switched alexandrite laser irradiation on dermal melanocytes of nevus of Ota. METHODS: Multiple biopsies were carried out on 4 patients with nevus of Ota before and after laser irradiation. Altogether 11 samples were examined under light microscope and 14 under transmission electron microscope. RESULTS: Immediately after laser irradiation, the dermal melanocytes were destroyed, the melanosomes were degenerated with central vesicle formation within most of them, and intradermal round vacuoles appeared. The epidermis remained intact. Three months to 1 year after irradiation, the degenerated melanosomes and cell debris were scavenged mainly by macrophages. Dermal melanocytes gradually decreased. No fibrosis was found. CONCLUSION: Q-switched alexandrite laser can selectively destroy dermal melanocytes of nevus of Ota and treat the disease safely.

Mobilization of Melanocytes During NB-UVB Treatment of Vitiligo

Vitiligo,a common skin depigmentation disorder,is the result of complex interactions of genetic,immunological,environmental,and biochemical events.Treatments for vitiligo include drugs,phototherapy,surgical transplantation,and so on.Among them,the efficacy of narrow band-ultraviolet B has been confirmed.By inducing keratinocytederived factors and signalings,narrow band-ultraviolet B can trigger and/or promote the mobilization of melanocytes which migrate to lesional epidermis ultimately,leads to the repigmentation of white patches.The mobilization of melanocytes includes stages of activation,migration,proliferation,and differentiation.Elucidating processes that enable the specific mobilization of melanocytes and the signaling pathways and factors involved,will help the development of new drugs and methods for the treatment of vitiligo.