Overexpression of thioredoxin-1 enhances angiogenesis and survival in a mouse ischemic skin flap model.

BACKGROUND Ischemia is a complication that can lead to failure of skin flap reconstruction. Thioredoxin-1, a redox protein, enhances recovery in ischemic models of myocardial infarction, peripheral vascular disease, and full-thickness wounds. This study examined the survival effect of thioredoxin-1 overexpression on an ischemic skin flap. METHODS A 3-sided 1.25 × 2.25 cm dorsal ischemic skin flap was made in B6 wild-type mice and transgenic mice overexpressing thioredoxin-1 (Trx-1Tg/+). A silicone sheet was placed under the flap to promote healing from the proximal end of the skin flap, creating an ischemic gradient. Images were taken on postoperative days 4, 8, and 12 to assess tissue viability and perfusion. Mice were killed on postoperative day 12, and skin flaps were collected and processed for histopathologic and immunohistochemical analysis. Immunofluorescence analysis was performed to determine the mechanism of wound healing mediated by thioredoxin-1. RESULTS Skin flap survivability was significantly improved in Trx-1Tg/+ mice compared with wild-type mice on postoperative days 4, 8, and 12. Doppler analysis showed enhanced perfusion of the distal skin flaps of Trx-1Tg/+ mice compared with wild-type mice. PHD1 and TXNIP expression by immunofluorescence analysis was decreased, whereas thioredoxin-1, vascular endothelial growth factor, Bcl-2, HO-1, and HIF1α expression was increased in the Trx-1Tg/+ mice compared with wild-type mice. Increased vessel density was observed in the skin flap by CD31 staining in Trx-1Tg/+ mice compared with wild-type mice. CONCLUSION Overexpression of thioredoxin-1 improves skin flap survivability by promoting angiogenesis, reducing oxidative stress, and preventing apoptosis by inhibiting prolyl hydroxylase 1. In the future, thioredoxin-1 treatment may be used in reconstructive procedures such as local tissue rearrangement and split- or full-thickness skin grafts.