Methods. Diabetic mice (C57BKS.Cg-m +/+ Leprdb female mice) with 1 cm × 1 cm excisional wounds were intradermally injected with 60 g of plasmid DNA encoding TGF-1 gene. The wound closure was measured up to 14 days postwounding. At days 7 and 14 postwounding, sections of skin were taken for hematoxylin and eosin and Masson's trichome staining to examine the morphology and collagen deposition. The cell proliferation and TGF-1 gene expression were studied using immunohistochemical stainings for 5-bromo-2-deoxy-uridine and for TGF-1.

Results. A higher cell proliferation rate and a denser and more organized new extracellular matrix were observed in the treated wound site. Complete wound closure was detected as early as 7 days for TGF-1-treated group in comparison with 11-14 days for the untreated, control plasmid DNA- and PBS-treated groups.

Conclusion. A single intradermal injection of TGF-1 plasmid DNA was sufficient to enhance wound healing. This approach represents a new strategy that may be applied to the treatment of excisional wounds in human diabetic patients.