Cultured human dermal papilla cells secrete a chemotactic factor for melanocytes.

Large numbers of pigmented melanocytes are located in human hair follicles, predominantly around the dermal papillae, and the number of melanocytes and the melanogenic activity of the hair follicles are closely related to the hair cycle. We found that cultured human dermal papilla cells secreted a melanocyte chemoattractant into the medium. Skin fibroblasts also showed weak chemoattraction of melanocytes, while skin keratinocytes and melanocytes did not. Since this chemotactic activity was heat-and protease-sensitive and was present in the relatively high molecular weight fraction (130-200 kDa), it may be due to extracellular matrix (ECM) that proteins secreted from the cultured dermal papilla cells. This chemotactic signal between dermal papillae and melanocytes may control the localization and migration of hair melanocytes in vivo.