Melanogenesis In Cultures Research Articles

Effect of keratinocytes on regulation of melanogenesis in culture of melanocytes

Melanocytes are the melanin-producing cells by melanogenesis, and the pigment melanin is primarily responsible for the color of skin. These cells contain dendrites that are in close contact with neighboring keratinocytes. Keratinocytes produce and secrete factors that regulate the proliferation and melanogenesis of melanocytes in vitro. Therefore, adopting only melanocyte pure culture may not clearly reflect the skin physiology in vivo. In this study, we applied a two-culture model using melanocytes and keratinocytes from human skin, such as melanocyte pure culture and melanocyte co-culture with keratinocyte. And then, there was compared the responses of melanocytes under different culture conditions (treatment with arbutin, MSH-α and UV-B irradiation). The results show that there was no significant difference in melanocyte proliferation and melanogenesis between arbutin and MSH-α treatment. However, the co-culture model was more stable than the pure culture model in terms of melanocyte proliferation and melanogenesis upon UV-B irradiation. Therefore, the co-culture model was superior to the pure culture as a useful method for the study of melanocytes and epidermal melanin unit.

Effects of endothelin antagonist on melanogenesis of cultured B16 murine melanoma cells.

Objective To evaluate the biological effect of endothelin (ET) antagonist on cultured B16 murine melanoma cells. Methods B16 murine melanoma cells were cultured in the presence of various concentrations (31.25, 62.5, 125, 250, 500 μg/mL) of ET antagonist or licoflavone. Then, melanoma cells were harvested for the detection of tyrosinase activity and melanin content. The proliferation rate of melanoma cells was measured with MTT method. The effect of ET antagonist was compared with that of licoflavone. Results Licoflavone had a concentration-dependent inhibition on melanogenesis. The ET antagonist selectively suppressed the ET-induced stimulation of tyrosinase and cell differentiation of B16 cells, but had no direct inhibitory effect on melanogenesis in culture, and little influence on melanocyte viability. The addition of ET antagonist at 200 μg/mL could significantly inhibit ET (0.5 μg/mL)-induced melanogenesis in Bl6 cells. The cytotoxity of the antagonist was relatively lower than that of licoflavone. Conclusions The results suggest that the ET antagonist is a safe skin-whitening ingredient, and may have a wide application perspective in the prevention of endothelin-induced skin pigmentation after UVB irradiation. Key words: Licoflavoue; Endothelins; Monophenol monooxygenase

Substratum effects on cell dispersal, morphology, and differentiation in cultures of avian neural crest cells

Adhesive extracellular matrix (ECM) molecules appear to play roles in the migration of neural crest cells, and may also provide cues for differentiation of these cells into a variety of phenotypes. We are studying the influences of specific ECM components on crest differentiation at the levels of both individual cells and cell populations. We report here that the glycoproteins fibronectin and laminin differentially affect melanogenesis in cultures of avian neural crest-derived cells. Clusters of neural crest cells were allowed to form on explanted neural tubes for 24 and 48 hr, and then subcultured on uncoated glass coverslips or coverslips coated with fibronectin or laminin. The morphology of cells varied on the three substrata, as did patterns of cell dispersal. Crest cells dispersed most rapidly and extensively on fibronectin. In contrast, cells on laminin dispersed initially, but then assumed a stellate morphology and rapidly formed small aggregates. Cell dispersal was minimal on glass substrata, resulting in a uniformly dense distribution. These patterns of dispersal were similar in subcultures of both 24- and 48-hr clusters, although dispersal of cells from older clusters was less extensive. The rate and extent of melanogenesis correlated with patterns of cell dispersal. Cells from 24-hr clusters underwent melanogenesis significantly more slowly on fibronectin than on the other two substrata. Pigment cells began to differentiate by 2 days of subculture in the cell aggregates on laminin and in the dense centers of cultures on untreated glass. By 5 days, there was significantly more melanogenesis in cultures on laminin and glass than on fibronectin substrata. Melanogenesis in cultures of 48-hr clusters was more rapid and extensive on control (glass) substrata than on fibronectin or laminin, correlating with reduced cell dispersal. We conclude that fibronectin and laminin, which are found along neural crest migratory pathways in vivo, can affect melanogenesis in vitro by regulating patterns of cell dispersal.

Interferon inhibits melanogenesis in b-16 mouse melanoma cells

Summary Mouse L-cell interferon (IF) (0.03–30 units/ml) produces a concentration-dependent inhibition of both spontaneous and melanocyte hormone stimulated (MSH) melanogenesis in cultures of murine B-16 melanoma cells. This inhibition is synergistic with that produced by the tumor promoter 12-0-tetradecanoylphorbol-13 acetate (TPA). Both TPA and IF also inhibit the expression of tyrosinase activity. These and previous results suggest that the antitumor effects of IF may be due to modulation of cellular differentiation.

Melanogenesis in cultures of peripheral nervous tissue: I. The origin and prospective fate of cells giving rise to melanocytes

Chick embryo spinal ganglia, peripheral nerves, and connective tissue usually associated with ganglia were cultured separately using several combinations of media and substrata. Melanocytes appear in cultures of both ganglia and peripheral nerves. The only cell type common to both the ganglion and peripheral nerve that could account for the observed pigment cells was the population of small cells with intensely staining nuclei that normally associates closely with nerve cell bodies and fibers. These cells could be distinguished morphologically from fibroblastic cells, which originated in the connective tissue capsule and did not undergo melanogenesis. We conclude that these small cells are supportive (Schwann, satellite, and perineurial) cell precursors and are one source of melanocytes in cultured peripheral nervous tissue.

Melanogenesis in cultures of peripheral nervous tissue: II. Environmental factors determining the fate of pigment-forming cells

Spinal ganglia from 4- to 7-day [Stage 23–30; Hamburger and Hamilton (1951) J. Morphol. 88, 49–92 ] chicken embryos were cultured in vitro to investigate the effect of various environmental conditions on cell differentiation. Culture morphology (i.e., degree of dispersion of the explanted ganglia, survival of neurons, and outgrowth of axons) was observed to depend upon several factors including: (1) the age of the explanted ganglia, (2) the presence or absence of nerve growth factor (NGF), and (3) the nature of the substratum on which the cultured tissue resides. These observations enabled us to disturb the association of neurons with the other cells in ganglion cultures and thereby modulate the differentiation of adventitious melanocytes. Thus, in medium permissive for melanogenesis, melanocytes appear when the association between neurons and small stellate nonneuronal cells in the ganglion is disrupted. This disruption is most extensive (1) when young (Stage 26–27, 5-day) ganglia are explanted on plastic substrata, in the initial absence of NGF, and (2) when cells from enzyme-dissociated ganglia are cultured on plastic substrata. In comparable media, pigment cell differentiation is not observed when the association between neurons and small stellate cells is preserved. Such associations tend to endure (1) in developmentally older (Stage 30+, 7- to 8-day) ganglia or (2) when ganglia are cultured on agar or fibroblast substrata. We conclude that loss of association between neurons and the nonneuronal cells in young ganglia is necessary for the latter to undergo melanogenesis in vitro.