Fetal Epidermal Keratinocytes (FEK)

The epidermal layer of the skin provides an essential function as a protective barrier against insults from the external environment. The predominant cell type in the epidermis is keratinocytes and they are located in the stratified squamous epithelia.Progenitors of keratinocytes reside and divide in the basal layer of the epidermis. They then differentiate, migrate towards the surface of epidermis, and eventually withdraw from the cell cycle permanently. Researches suggest that the majority of calcium-binding proteins (CaBPs)  in amniotic fluid consist of two distinct S100 proteins, calcium-binding protein in amniotic fluid-1(CAAF1) and CAAF2, which are produced by fetal epidermal keratinocytes.