Differences in Subcellular Distribution of Catechol-O-Methyltransferase and Tyrosinase in Malignant Melanoma

Some aspects of melanin formation of melanocytes cultured on collagen-coated microcarrier beads

Melanocytes cultured on collagen-coated Cytodex 3 microcarrier Sephadex beads caused remarkable pigmentation of the beads during the period of culture when optimal density was reached. Electron microscopy of melanocytes on the microcarriers revealed that the cells and their dendrites invaginate into the microcarrier surface layer. Removal of the cells by trypsinization showed that some pigment granules were left on the carrier surface and within the cavities present on the microcarrier surface. In order to investigate whether the pigmentation of the microcarriers could be a result of indole intermediates of melanogenesis present in the culture medium, extracts were studied by gas chromatography/mass spectrometry for the presence of these compounds. Two compounds (5,6-dihydroxyindole-2-carboxylic acid and 6-hydroxy-5-methoxyindole-2-carboxylic acid) so far have been identified in the medium extracts. Results indicate that microcarrier culture of melanocytes can serve as an interesting model for electron microscopy studies of melanocytes with regard to pigmentation and cell attachment.