Non-skin mesenchymal cell types support epidermal regeneration in a mesenchymal stem cell or myofibroblast phenotype-independent manner.

Skin-derived fibroblasts, preadipocytes and adipocytes, and non-skin-derived bone marrow stromal cells support epidermal regeneration. It remains unclear, however, whether various organ-derived mesenchymal cell (MC) types other than the aforementioned counterparts affect epidermal regeneration. Using a skin reconstruction model, it is shown here that heart-, spleen-, lung-, liver- and kidney-derived MC support epidermal regeneration by keratinocytes. Immunohistochemistry showed that these MC types described here allowed keratinocytes to express cytokeratin (CK) 10, CK14 and involucrin in a normal fashion, and to retain the epidermal progenitor cell marker, p63, within the basal layer. MC types constantly expressed vimentin, but they were heterogeneous in their expression of the mesenchymal stem cell markers, stage-specific embryonic antigen-4, CD105, CD90 and CD44, and the myofibroblast marker, alpha-smooth muscle actin. The MC types expressed keratinocyte growth factor, stromal-derived factor-1 and interleukin-6, which are all critical for dermal fibroblast-keratinocyte interaction. These results indicate that vimentin-positive MC originating from the heart, spleen, lung, liver and kidney can support epidermal regeneration without the involvement of mesenchymal stem cell and myofibroblast phenotypes of MC.