Characterization of adipose tissue macrophages and adipose-derived stem cells in critical wounds

Background. Subcutaneous adipose tissue is a rich source of adipose tissue macrophages and adipose-derived stem cells which both play a key role in wound repair. While macrophages can be divided into the classically-activated M1 and the alternatively-activated M2 phenotype, ASCs are characterized by the expression of specific stem cell markers. Methods. In the present study, we have investigated the expression of common macrophage polarization and stem cell markers in acutely inflamed adipose tissue. Subcutaneous adipose tissue adjacent to acutely inflamed wounds of 20 patients and 20 healthy subjects were harvested and underwent qPCR and flow cytometry analysis. Results. Expression levels of the Ml-specific markers CD80, iNOS, and IL-lb were significantly elevated in inflammatory adipose tissue when compared to healthy adipose tissue, whereas the M2-specific markers CD163 and TGF-beta were decreased. By flow cytometry, a significant shift of adipose tissue macrophage 1populations tow ards the M1 phenotype was confirmed. Furthermore, a decrease in the mesenchymai stem cell markers CD29, CD34, and CD105 was observed whereas CD73 and CD90 remained unchanged. Discussion. This is the first report describing the predominance pf M1 adipose tissue macrophages and the reduction of stem cell marker expression in acutely inflamed, non-healing wounds.