Pheomelanin content of cultured human melanocytes from lightly and darkly pigmented skin: A pyrolysis-gas chromatography/tandem mass spectrometry study

The diverse susceptibility of human skin with various degree of constitutive pigmentation to UV-induced damage, including carcinogenesis, may result from the differences in both total melanin content and the pigment composition, in particular the proportion of potentially harmful pheomelanin. The aim of this study was to compare a pheomelanin content of human epidermal melanocytes derived from lightly and darkly pigmented neonatal skin, using the previously developed method based on the thermal degradation of the pigment. Melanin was isolated from the cultured cells and pyrolysed at 500 degrees C with a microfurnace-type device. The obtained pyrolysates were analyzed for the presence of the marker degradation products using a gas chromatography/tandem mass spectrometry system operating in a multiple reaction monitoring mode. The pheomelanin content was calculated from a calibration curve, generated with the use of a series of synthetic melanin pigments with known percentages of incorporated pheomelanin. We have found that the pheomelanin content of human epidermal melanocytes from neonatal skin does not exceed 10 pg per cell, and depends on the degree of constitutive pigmentation. Heavily pigmented melanocytes derived from dark skin produce approximately four times as much pheomelanin as the cells from light skinned donors. (C) 2017 Elsevier B.V. All rights reserved.