The aging epidermal skin niche

Abstract Skin stem cells have been identified at various locations in the epithelium including the interfollicular epidermis, hair follicles and sweat glands given that this compartment of the skin undergoes rapid renewal continuously. In contrast, the stem cells of the underlying dermis or connective tissue of the skin, remain poorly defined, although the ability of subpopulations of dermal fibroblasts to give rise to lineages not normally derived from these cells in the skin such as bone, cartilage and fat have been investigated. The dermis acts as a mesenchymal niche for the epidermis secreting adhesive and growth promoting factors required for epidermal renewal. The dermis has been well studied in the context of aging given the obvious macroscopic changes it accumulates. This review focusses on our current understanding of how the observed changes in the dermis may impact on the homeostatic renewal of the interfollicular epidermis of the skin with aging.