The reconstruction of skin equivalents with hair follicle dermal sheath cells

Abstract

The skin consists of two main layers, the epidermis and dermis, which are separated by the basement membrane. Epidermal-dermal communication is important for skin homeostasis, and dermal factors play a key role in regulating the growth and differentiation of the epidermis. Several studies have demonstrated that hair follicle dermal sheath cells (DSCs) synthesize more soluble factors than dermal fibroblasts. The aim of this study is to investigate the effects of DSCs upon the evolution of skin equivalents (SEs). In this study, human keratinocytes were seeded on two different dermal substitutes. In addition, the effects of ascorbic acid were evaluated. Histologically, thick epidermis was observed in DSC-derived models. Immunohistochemical staining showed similar pattern of involucrin in both DSC- and fibroblast-derived models, but filaggrin was expressed much stronger in DSC models. The number of PCNA positive cells was lower in the DSC model than in the fibroblast model especially in the presence of ascorbic acid. However, integrin a6 was strongly expressed in DSC models and in the presence of ascorbic acid supplementation. These findings suggest that DSCs secrete or synthesize factors, which affect the epidermalization of the skin, and that ascorbic acid is an important supplement in the reconstruction of human epidermis. In addition, transmission electron microscopy of SEs was performed and a well-developed intercellular junction was observed in the DSC models. Our results suggest that dermal compartment-related epidermis modifications are important in the processes of differentiation and proliferation in SEs.