Optimization of the method for the culture of melanocyte precursors from hair follicles and their activation by 1,25-dihydroxyvitamin D3

The study optimized the method for culturing melanocyte precursors (MPs) from the outer root sheath of hair follicles, which are crucial for understanding vitiligo repigmentation. The cultured MPs initially showed no significant tyrosinase (TYR) activity or melanin synthesis, resembling their in vivo state. However, treatment with 1,25-dihydroxyvitamin D3 (VID) significantly promoted MP differentiation, as evidenced by increased dendritic morphology, positive DOPA staining, and the appearance of stage III and IV melanosomes. VID also enhanced the expression of microphthalmia-associated transcription factor (MITF), TYR, and tyrosinase-related protein-1 (TRP-1), leading to increased TYR activity and melanin levels, although these were still lower compared to cultured epidermal melanocytes. This research provided insights into the activation of MPs by VID, contributing to the understanding of its role in vitiligo treatment.