Tissue factor as a link between wounding and tissue repair

The initial phase of wound repair involves inflammation, induction of tissue factor (TF), formation of a fibrin matrix, and growth of new smooth muscle actin (alpha-SMA)-positive vessels. In diabetes, TF induction in response to cutaneous wounding, which ordinarily precedes increased expression of vascular endothelial growth factor (VEGF) and alpha-SMA transcription, is diminished, though not to a degree causing excessive local bleeding. Enhanced TF expression in wounds of diabetic mice caused by somatic TF gene transfer increased VEGF transcription and translation and, subsequently, enhanced formation of new blood vessels and elevated blood flow. Furthermore, increased levels of TF in wounds of diabetic mice enhanced wound healing; the time to achieve 50% wound closure was reduced from 5.5 days in untreated diabetic mice to 4.1 days in animals undergoing TF gene transfer (this was not statistically different from wound closure in nondiabetic mice). Thus, cutaneous wounds in diabetic mice display a relative deficiency of TF compared with nondiabetic controls, and this contributes to delayed wound repair. These data establish TF expression as an important link between the early inflammatory response to cutaneous wounding and reparative processes.