Melanoblasts, the precursors to melanocytes, originate in the neural crest. Some melanoblasts can travel to the hair follicle and further differentiate into pigment melanin-producing melanocytes. Hair follicles contain a pool of undifferentiated melanocyte stem cells (MSCs), which are sources of differentiated melanocytes, and functional melanocytes exhist in the hair bulb. The volume, life, and activity of melanocytes in a hair follicle is closely related with the growth cycle of follicle. Appearance of gray hair gray results from incomplete MSCs maintenance.
Aging ; physiology ; Cell Differentiation ; Hair Follicle ; cytology ; physiology ; Humans ; Melanocytes ; physiology ; Stem Cells ; physiology

The pattern and morphology of cellular infiltration of iris melanocytes implanted into the corneal stroma were studied with a rabbit corneal model. Iris melanocytes are transformed into fibroblast-like cells with a loss of pigment granules, which may reflect the in vivo characteristics of iris melanocytes under pathologic conditions. The metaplastic chararter of iris melanocytes appears to be related to the formation of retrocorneal pigmentation and fibrous membrane.
Animals ; Cell Division ; Cornea/*cytology/pathology/surgery ; Iris/*cytology ; Melanocytes/*cytology/physiology/transplantation ; Metaplasia/pathology ; Rabbits

Melanosome is a cellular organelle that is composed of a melanosomal matrix and a brown biochrome, melanin which is formed by tyrosine-tyrosinase reactions. The melanosome is formed within the melanocyte and transferred to the surrounding keratinocytes through dendritic processes. Human skin color is related to the number, size, type and distribution of melanosomes, and the major role of melanosomes is to prevent skin from injurious nonionizing ultraviolet radiation. Controlled NaOH hydrolysis and centrifugation of human hair make it possible to isolate large amounts of melanosomes which are synthesized within the follicular melanocytes and transferred to hair matrix cells. In this study, the sun protection factors of topically applied melanosomes isolated from human hair were evaluated using ultraviolet B phototesting. Topically applied melanosomes increased the minimal erythemal doses. And the sun protection factors of each 50% and 25% melanosomal preparation were 12.3 +/- 5.5 and 3.1 +/- 1.3 respectively, and these ultraviolet B protection effects showed statistically significant differences from 10%, 5% and 1% melanosomal preparations and vehicle. Form these results, the dose-related photoprotective role of melanosomes was confirmed.
Human ; Male ; Melanocytes/*physiology ; Skin/*radiation effects ; Support, Non-U.S. Gov't ; Ultraviolet Rays/*adverse effects

Antigens, CD34 ; metabolism ; Biomarkers ; metabolism ; Cell Differentiation ; physiology ; Hair Follicle ; cytology ; Humans ; Intramolecular Oxidoreductases ; metabolism ; Keratinocytes ; metabolism ; Melanins ; metabolism ; Melanocytes ; metabolism ; PAX3 Transcription Factor ; metabolism ; Stem Cells ; metabolism

Pigmentation may result from melanocyte proliferation, melanogenesis, migration or increases in dendricity. Recently, it has been reported that secreted phospholipase A2(sPLA2) known as a component of bee venom (BV), stimulates melanocyte dendricity and pigmentation. BV has been used clinically to control rheumatoid arthritis and to ameliorate pain via its anti-inflammatory and antinociceptive properties. Moreover, after treatment with BV, pigmentation around the injection sites was occasionally observed and the pigmentation lasted a few months. However, no study has been done about the effect of BV on melanocytes. Thus, in the present study, we examined the effect of BV on the proliferation, melanogenesis, dendricity and migration in normal human melanocytes and its signal transduction. BV increased the number of melanocytes dose and time dependently through PKA, ERK, and PI3K/Akt activation. The level of cAMP was also increased by BV treatment. Moreover, BV induced melanogenesis through increased tyrosinase expression. Furthermore, BV induced melanocyte dendricity and migration through PLA2activation. Overall, in this study, we demonstrated that BV may have an effect on the melanocyte proliferation, melanogenesis, dendricity and migration through complex signaling pathways in vitro, responsible for the pigmentation. Thus, our study suggests a possibility that BV may be developed as a therapeutic drug for inducing repigmentation in vitiligo skin.
Animals ; Base Sequence ; Bee Venoms/*pharmacology ; Cell Movement/drug effects ; Cell Proliferation/drug effects ; Cells, Cultured ; Cyclic AMP/metabolism ; DNA Primers/genetics ; Forskolin/pharmacology ; Gene Expression/drug effects ; Humans ; Melanins/biosynthesis ; Melanocytes/cytology/*drug effects/physiology ; Microphthalmia-Associated Transcription Factor/biosynthesis/genetics ; Monophenol Monooxygenase/biosynthesis/genetics ; Signal Transduction/drug effects