MELANOGENESIS BY HUMAN UVEAL MELANOCYTES IN-VITRO

Purpose. To study melanogenesis by cultured human uveal melanocytes, a nd the relationship between melanin production by uveal melanocytes in vitro with the degree of iris pigmentation in vivo. Methods. Melanin content, melanin production, and tyrosinase activity of cultured uveal melanocytes derived from eyes of various iris color were measured at different stages of cultivation. Results. Cultured weal melanocytes ma intained a constant level of melanin content, expressed tyrosinase act ivity, and produced measurable amounts of melanin in vitro. Melanosome s in different stages were seen ultrastructurally. Melanin production correlated directly with the degree of iris pigmentation of the eyes f rom which the uveal melanocytes were isolated. u Tyrosinase activity o f cultured uveal melanocytes from black versus white donors was signif icantly different, but, among white donors, there was no correlation w ith iris pigmentation or with melanin production in vitro. Conclusion. Cultured uveal melanocytes can produce melanin in vitro. Cultured uve al melanocytes isolated from eyes of different iris color maintained t heir inherent capacity for malano-genesis. Therefore, cultured uveal m elanocytes are an excellent model system for studying melanogenesis in uveal melanocytes in vitro.