The apparent need of an autologous cell source for tissue engineering applications has led researchers to explore the presence of cells with stem cell plasticity in several human tissues. Dermal fibroblasts (FBs) are easy to harvest, expand in vitro and store, rendering them plausible candidates for cell-based therapies. The aim of the present study was to observe the effects of adipogenic, chondrogenic and osteogenic induction media on the phenotype of human FBs. Human preadipocytes obtained from fat tissue have been proposed as an adult stem cell source with suitable characteristics, and were used as control cells in regard to their differentiation potential. Routine staining, immunohistochemical analysis and alkaline phosphatase assay were employed, in order to study the phenotypic shift. FBs were shown to possess multilineage potential, giving rise to fat-, cartilage- and bone-like cells. To exclude contaminant progenitor cells or cell fusion giving rise to tissue with adipocyte-, chondrocyte- and osteoblast-like cells, single-cell cloning was performed. Single-cell-cloned FBs (sccFBs) displayed a similar differentiation potential as primary-culture FBs. The presence of ‘stem-cell-specific’ surface antigens was analyzed using flow cytometry. The results reveal that sccFBs have several of the markers associated with cells exhibiting stem cell plasticity. The findings presented here are corroborated by the findings of other groups, and suggest the use of human dermal FBs in cell-based therapies for the reconstruction of fat, cartilage and bone.

Using the freeze-thaw method, optimal preparation of PL with regard to the concentration of growth factors was achieved at Cycles 3 to 5. Based on our findings, the clinical significance of using a greater number of cycles is likely limited.

Persistent and impaired inflammation impedes tissue healing and is a characteristic of chronic wounds. A better understanding of the mechanisms controlling wound inflammation is needed. In this study, we show that in human wound-edge keratinocytes, the expressions of microRNA (miR)-17, miR-18a, miR-19a, miR-19b, and miR-20a, which all belong to the miR-17w92 cluster, are upregulated during wound repair. However, their levels are lower in chronic ulcers than in acute wounds at the proliferative phase. Conditional knockout of miR-17w92 in keratinocytes as well as injection of miR-19a/b and miR-20a antisense inhibitors into wound edges enhanced inflammation and delayed wound closure in mice. In contrast, conditional overexpression of the miR-17w92 cluster or miR-19b alone in mice keratinocytes accelerated wound closure in vivo. Mechanistically, miR-19a/b and miR-20a decreased TLR3-mediated NF-kB activation by targeting SHCBP1 and SEMA7A, respectively, reducing the production of inflammatory chemokines and cytokines by keratinocytes. Thus, miR-19a/b and miR-20a being crucial regulators of wound inflammation, the lack thereof may contribute to sustained inflammation and impaired healing in chronic wounds. In line with this, we show that a combinatory treatment with miR-19b and miR-20a improved wound healing in a mouse model of type 2 diabetes.

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