Modulation of the Differentiated Phenotype of Keratinocytes of the Hair Follicle and Epidermis

The study reviewed the differentiation capacity of epithelial cells from the epidermis, hair follicle outer root sheath, and hair matrix cells, focusing on their modulation by cell-cell and cell-matrix interactions. It was found that while these cells could form stratified and keratinizing epithelia in vitro, their differentiation levels varied, with hair matrix cells showing the least differentiation, especially in the presence of dermal papilla cells. The research demonstrated that skin and appendage-keratinocytes maintained their ability to reconstitute a squamous epithelium, indicating a common embryonic origin. However, achieving hair follicle-specific characteristics required more complex interactions, which had not been successfully replicated in vitro.