FETAL HUMAN MELANOCYTES - IN-SITU DETECTION, IN-VITRO CULTURE AND DIFFERENTIATION CHARACTERISTICS AT 6-11 WEEKS EGA

In vivo, melanocytes were detected in epidermis from human tissue of 6 .5 weeks estimated gestinational age (EGA) and older. We have successf ully established melanocyte monocultures from tissue of 9 to 10 weeks EGA. To our knowledge, this is the first report on physiology of human foetal melanocytes in monoculture. In culture, such melanocytes retai ned foetal characteristics. Proliferation rates noted were markedly hi gher (approximately 2.7-fold) when compared to those in cultures of ne onatal melanocytes. Moreover, when analyzing cellular phenotypes by ma rkers for cells of the melanocytic lineage, foetal cells isolated from tissue of 9 weeks EGA reproducibly showed expression of the high mole cular weight (HMW) antigen and c-kit to an extent intermediate to that found in neonatal melanocytes and M14 melanoma cells. Such differenti al expression was not observed if cells were isolated from tissue of 1 0 weeks EGA, indicating that the foetal environment provides essential differentiation stimuli during the 10th week of gestation. Moreover, these results are supportive of the theory that malignant transformati on involves a process of dedifferentiation. In all, human foetal melan ocyte culture provides a useful model to investigate pigment cell diff erentiation.