All Melanocytes, derived from iPSC, are available in 4 human phototypes:
Caucasian, Asian, African and Albino.
Melanocytes are cells that synthesis melanin, a pigment responsible for skin colour and UV protection. Depending on their location : skin, hair, or eye, we distinguish three kinds of melanocytes. We will focus on the one present inside the skin, more precisely at the epidermis bottom, in what we call the basement membrane. Melanocytes are the second biggest cell population in epidermis. Tanning can be summarized easily. Melanocytes are the producer of melanin and keratinocytes are the user of this UV protective pigment. The transfer of melanin from melanocytes to keratinocytes is ensured by melanosomes: vesicle secreted by melanocytes, and carrying melanin. There are two kinds of melanin: eumelanin for brown colour and pheomelanin for yellow/red colour. The process of melanin production is called melanogenesis and differ in the last stages between eumelanin and pheomelanin. Everyone has a different ratio of these two melanins, which will determine six different phototypes (Table - The Fitzpatrick classification). Each phototypes will react differently to sun’s UV depending on their melanin content.
Scientific data show that for each phototypes, while there is roughly the same number of melanocytes per skin surface, the differences observed come from melanosomes. For instance, the melanosome’s shape, size, organisation, or transfer is completely different for type I and type VI. Such results emphasize the importance of working with melanocytes of the right phototype when developing new ingredients or formula, as pigmented cells from Caucasian, Asian or African skins will not display the same behaviour.