| amelanotic melanocytes of outer root sheath in hair follicle have great influence to hair pigment. As one of the clinical familiar hair pigment disorder, canities can not give rise to serious system disease, but in view of hair play an important role in social communication, premature hair graying or canities has significant adverse effects on the specious, self-esteem and social-cultural acceptance of the affected individualAs rhythm of life accelerating and social stress increasing, the origination age of canities not only presents younger, incidence of canities also show a rising trend.[1]As standard of living and the requipment of self image improving,more and more people look for a more effective way to reverse hair greying.The most usual type of canities is age-induce hair greying and premature greying.hair dye is used to pigment white hair, but it injure hair color and may be associated with an increasing risk of developing certain cancers.[2] As we all known, hair pigment depends on the number and type of melanin secreted by melanosome. Lack of hair bulb melanocytes (PDMCs)and dysfunction lead to hair greying. [3]The precursor cells of melanocytes called melanoblasts, stem from the neural crest in vertebrates. During embryogenesis phase,the melanoblasts migrate away from the neuroepithelium in an particular journey with cycles of migration and proliferation to finally locate the skin and the hair follicle(HF).During the embryogenesis of mice, from E10.5 to E13.5(embryonic day), the melanoblasts appear upward through the development into the epidermis, at E14.5, they enter the newly developing hair follicle and only locate in the HFs after brith.In the HF from E17.5 to P0, the melanoblasts are differentiated into two populations:one locates in hair matrix where the melanoblasts are differentiated into completely mature melanocytes; and the other colonizes the bulge region, where the melanoblasts are restricted in a resting status to become the melanocyte stem cells(McSCs).(11)In adult human, in the onset of a new anagen, the active phase of the hair cycle, the McSCs proliferate, and lead to melanocyte progenitor cells. These transient amplifying cells are proliferative progenitor cells locate in the outer root sheath.The melanocyte progenitors then differentiate to yield mature melanocytes presented in hair bulb. Hair follicle melanocytes are made up of two morphologically and functionally different types:(ⅰ) the pigmented melanocytes (PDMC)is big, intensely pigmented, dendritic and dopa-positive, presenting in the hair infundibulum and bulb; and (ⅱ) AMMC is lathy, bipolar, non-dendritic and dopa-negative,locating in the ORS of the middle and lower hair follicle. AMMC proliferate well in culture, but the intensely pigmented hair follicle melanocytes do not. The ultrastructure of PDMC is characterized by four-stage melanosomes.StageⅠpre-melanosomes correspond to maturing multivesicular endosomes are characterized by rich planar bilayered clathrin coats. Specific sorting and processing events promote the formation of striated stageⅡ pre-melanosomes. Melanin synthesis begins in stageⅢ melanosomes with melanin deposits obvious on internal striations. StageⅣ melanosomes are mature, instenly pigmented, and ready to be transferred into keratinocytes.in AMMC,there are stagel and Ⅱ melanosomes, and some stageⅢ melanosomes without stageⅣ melanosomes in cytoplasm.PDMC is authenticated by Dct+、Kit+、Mitf+、Pax3+、Sox10+、tyr+、 Mclr+; AMMC keep in low standard of differetation and melanogenesis, do not express tyr+、Mclr+; McSC only express Dc+、Pax+、Sox10+。One principal difference between these two pigmentary processes is that epidermal pigmentation is around-the-rock,while hair pigmentation is matched with the hair cycle. The hair cycle, first described in, consists of phases of anagen, catagen and telogen, which are controlled in part by apoptotic processes.McSCs differenate into two cell types during early anagen,locate in two compartments of the hair follicle:in the anagen hair bulb, where they transfer pigment to cells which will form the hair cortex, and in the outer root sheath (ORS). ORS melanocytes are sparsely presented in the basal layer of the epithelium along the length of the follicle that are non-melanized. However, recent studies suggest that grey hair follicles lack of melanocytes in the hair bulb while retaining those in the ORS. Hair bulb melanocytes may be recruited from the ORS melanocyte population at the initiate of anagen. Tyrosinase activity becomes apparently during anagen Ⅲ, pigment transfer from hair bulb melanocytes to keratinocytes is initiated during anagen IV and actived melanogenesis continues throughout anagen V and VI, stoping with the onset of catagen.The average length of human scalp hair cycle is about 3.5 years,and the average time before hair greying starts is about 35-40 years, suggesting about 10 hair cycles before the initiation of greying.after almost 10 hair cycles, each new cycle shows a certain loss of active melanogenesis, resulting in increasing numbers of hair shafts with grey hairs, or with a total lack of pigment deposition.This topic research mainly includes two aspects1, Explored A More Optimization Method Of Almelanotic Melanocytes CultivationDue to hair follicles are easy to obtain, and contain many stem cells nearly 12% of all, in regenerative medicine, hair follicles provide somatic cell therapy to treat burns patients, the repigment of vitiligo, and promote the healing of chronic ulcers and even playing an important role in nerve regeneration. Hair follicle melanocytes differenate into two types:PDMC in the hair bulb, where they transfer pigment to cells which will form the hair cortex, and AMMC in the outer root sheath (ORS). PDMC has highly differentiation,the ability of proliferation is limited, AMMC of outer root sheat is low differentiation, has apparent proliferation potential, therefore, the mode of AMMC culture in vitro can be used as a foundation to study white hair, the pathogenesis of vitiligo and other pigment disorder, can also be used for screening drugs and methods for treatment of these diseases.The mainmind of this research is to explore a more optimization method of almelanotic melanocytes cultivation. AMMC cultivation in vitro is roughly divided into direct extraction and enzyme digestion.the first step, the process of traditional enzyme digestion is complex, in order to optimize process of obtaining hair follicle, combined with FUE technology, speak enzyme digestion from three steps to two steps. The second step, in the foundation of FUE to obtain hair follicles, grope for optimum enzyme digestion time, compare the time and rate of cell emigration. The third step, compared direct extraction, enzyme digestion method and FUE+enzyme digestion: the same batch of hair follicles, use three different ways to obtain, placed in the same culture conditions, is concluded FUE+enzyme digestion, cultivation of hair follicle cells migration rate and time than traditional direct extraction method and enzyme digestion. Conclusion, combining FUE and enzyme digestion, can be greatly optimized cultutive of AMMC in vitro.2, observe AMMC morphological change in vitro cultivation, and the low oxygen intervention effects on AMMC.Hair follicle melanocytes are made up of two morphologically and functionally different types:(i) the pigmented melanocytes (PDMC)is big, intensely pigmented, dendritic and dopa-positive, presenting in the hair infundibulum and bulb; and (ii) AMMC is lathy, bipolar, non-dendritic and dopa-negative,locating in the ORS of the middle and lower hair follicle. During culture process in vitro, AMMC morphological changes, PO-P4 cells mainly by bipolar cells, dendritic cell content increasing, in P6 cells,dendritic cell type are mostly, and proliferation decrease.In indicates the change of differentiation and function. Low oxygen has important function to maintance morphology and function of precursor cells,avoiding precursor cells over differention. P3 AMMC_scratch test first,then respectively culture in the ordinary incubator and oxygen content 5% of hypoxic incubator intervention for 24 hours, low oxygen intervention AMMC migration and multiplication up regluate significantly. Conclusion, AMMC will further mature and lost its original characteristics in vitro, low oxygen plays an important role in to maintain cell properties. |
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