Ischemic Non-Healing Skin Wound Model: Cell Death and Wound Healing Mechanisms

The aim of the study was to develop an ischemic skin flap model in laboratory mice with the description of necrotic and apoptotic processes in time course, and demonstrate the regenerative characteristics of non-healing skin wound under the conditions of a formed flap. Materials and Methods. The study involved 20 BALB/c mice. The first experimental stage describes an ischemic flap on day 1, 2, 3, and 5 after flap formation using histology, immunofluorescence, morphometry, and TUNEL. At the second stage a non-healing wound was modeled on the flap, and its pathogenesis was histologically compared with an acute wound. Results. A formed flap showed such histological ischemic features as blood-filled vessels, micro blood clots in blood vessels, coagulation necrosis, migration of inflammatory cells, as well as extravasation, true skin edema and hyperproliferation of epithelial cells. Maximum pathological changes were found on the third postoperative day, and by day 5 the wound partially healed. Morphometry demonstrated a significant increase in blood-filled vessels and the tendency for epithelial layer reduction in a skin flap of experimental animals compared to the control ones. Apoptotic cells were observed on days 1, 2, 3, and 5 of a formed flap. Some areas showed cell clusters around hair follicles. No apoptotic cells were revealed in control animals. By the moment of complete regeneration of acute wounds, non-healing wounds exhibited no epithelialization and a formed mature cicatrix that enables to interpret the difference in wound healing as significant. Conclusion. Ischemia causes major pathological skin changes, as well as results in delayed wound healing. A developed non-healing wound model can be used to study wound healing mechanisms and the ways to influence them.