Background: Large or deteriorated skin defects are sometimes life threatening. There is increasing evidence that adult stem cells are useful for tissue regeneration. Human mesenchymal stem cells (hMSCs) are self-renewing and are potent in differentiating into multiple cells and tissues.
Objectives: To investigate the effects of hMSCs in cutaneous wound healing.
Methods: Wound healing was studied in an hMSC-populated porcine skin substitute, using a nude rat model to minimize immune reactions. Full-thickness skin and soft tissue defects of 1.5 x 1.5 cm in size, including the panniculus carnosus, were excised and covered with hMSCs and basic fibroblast growth factor (bFGF)-soaked skin substitutes and an evaluation was made of wound size, histology and protein expression at 3, 7 and 42 days after injury.
Results: The wound size was significantly smaller in the hMSC-treated groups (P < 0.01) and any dose of bFGF (1, 10, 100 microg) enhanced the healing (P < 0.01). The re-epithelialization markers integrin alpha3 and skin-derived antileucoproteinase were remarkably increased with the presence of bFGF in a dose-dependent manner, while the mesenchymal cell surface markers CD29 and CD44 were downregulated in a time-dependent manner. Human pancytokeratin, which does not cross-react with rat antigens, was observed by Western blotting at 38 kDa and 42 kDa from the hMSC-treated tissues on day 7. The expression levels were elevated by 10 microg bFGF (P < 0.01). The immunohistochemical expression of human pancytokeratin was only observed in the hMSC-treated groups.
Conclusions: These data suggest that hMSCs together with bFGF in a skin defect model accelerate cutaneous wound healing as the hMSCs transdifferentiate into the epithelium.