EVALUATION OF THE WOUND HEALING PROCESS BY IMMUNOHISTOCHEMISTRY AND PICROSIRIUS RED STAINING

Abstract

Non-healing wounds, also known as chronic wounds, are defined as wounds that do not show improvement in healing within four weeks. Chronic wounds affect millions of people around the world and health care expenses in the United States can cost more than one billion dollars. Chronic wound healing is a complicated process with different pathologies depending on the patients’ condition. Four highly integrated and overlapping phases compose the wound healing process: hemostasis, inflammation, proliferation, and tissue remodeling. Occurrence of chronic wounds is usually due to unsuccessful progression through the normal stages of healing, and frequently enters a state of pathologic inflammation. Several cell types are involved in the wound healing process. Platelets initiate the coagulation cascade to stop the bleeding. Keratinocytes are able to restore the epidermis after injury. Vascular endothelial cells form the new blood vessels. Neutrophils and macrophages are responsible for phagocytosis and the release of growth factors and cytokines. Fibroblasts secrete collagen to fill the wound gap. Skin or tissue grafting is one of the many ways to treat non-healing wounds. Currently available skin substitutes have been proven successful in clinical trials, but they have room for improvement. Long-term culturing for cellularized scaffolds, risk of transferring disease from allogeneic or xenogeneic sources, and mismatching mechanical properties limit current skin substitutes in clinical applications. Given the disadvantages of those skin substitutes, plant protein can be a potent and attractive replacement material. Plant proteins can be extracted from renewable resources in abundance. Compared to skin substitutes from porcine or bovine sources, plant protein scaffolds do not have issues with immune rejection and can be formed into gels, films, or fibers with good bio-compatibility. Amongst the many plant proteins, soy protein is one of the ideal materials to make skin substitute scaffolds. Soy protein has been confirmed to be bio-active in vivo and in vitro. In this study, soy protein-based tissue scaffolds (SPS) were applied in full thickness excisional wounds in a porcine model. Immunohistochemistry (IHC) analysis was performed for macrophage invasion, newly formed vessel formation, and picrosirius red staining of collagen deposition. Results from IHC analysis show that SPS can accelerate the wound healing process.