The extracellular matrix (ECM) is the largest component of the dermal skin layer and the synthesis of ECM is a key feature of wound healing, especially when there has been a significant loss of tissue that precludes closure by primary intention. This article discusses the proteins contained in the ECM of normal skin that are important in the healing of acute and chronic wounds. In addition, the theory that the high levels of proteases found in chronic wounds impair healing by degrading essential components of the ECM is discussed using data from cell culture experiments and immunohistochemical analyses of wound biopsies.
As a consequence of this theory new dressings have been developed that are designed to reduce protease levels in wound fluids by providing a competitive substrate (collagen) for the proteases and thereby reducing proteolytic destruction of essential ECM components (fibronectin) and platelet-derived growth factors (PDGFs). Other new approaches include the topical treatment of chronic wounds with agents that reduce the synthesis of matrix metalloproteinases (MMPs), such as a mixture of metal cations, and treatment with unique proteins (amelogenin) to replace the corrupted ECM.