Oral communication, CS6 / C20

Official XXIst International Pigment Cell Conference website - 21-24 Sept 2011, Bordeaux - France | updated: September 04 2011

Human hair pigmentation characteristics revealed by melanin determination in human eumelanic hairs of various ethnic origins

Studies carried out in human hair follicle revealed intriguing findings with regard to melanogenic enzyme expression in relation to eumelanin and pheomelanin synthesis, and pointed out unexpected hair-type particularities. Changes with age in human hair have also been revealed. More specifically, the loss of hair pigment leading to the visual greying of hair stems from a gradual and specific depletion of the pool of melanocyte progenitors hosted in each hair follicle. From a chemical point of view, however, data remains scarce regarding human hair pigmentation characteristics. Systematic melanin determination in human hair should give insights for understanding molecular controls of melanin synthesis and melanocyte phenotype within human hair bulbs. In an attempt to bring clues to this objective, we examined the quantity and quality of melanin in eumelanic hair in humans in relation to gender, to ancestry origins, and to age, in 168 individuals among African-American, East Asian, and Caucasian. We evidenced differences in melanin composition and content in relation to ethnic origins. Furthermore, our results gave evidence of an age-dependent increase in the pyrrole-2,3-dicarboxylic acid (PDCA) / pyrrole-2,3,5-tricarboxylic acid (PTCA) ratio in African-American and Caucasian hairs, suggesting a chronological evolution of hair follicle melanocyte phenotype (e.g. decrease in dopachrome tautomerase expression with age). In conclusion, we show, for the first time, clear evidence of age-dependent changes in the quantity and quality of eumelanin in pigmented human hairs. Furthermore, our results reveal differences in melanin composition in relation to ethnic origins in eumelanic human hairs.

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