The role of silver in wound healing - Part 3: Matrix metalloproteinases innormal and impaired wound healing: A potential role of nanocrystalline silver

Matrix metalloproteinases (MMP) are part of a group of proteolytic enzymes that are important in various repair and inflammatory processes. Dysregulat ion of MMPs and other proteinases has been linked to a number of pathologic processes, including such chronic inflammatory disorders as rheumatoid art hritis, periodontal disease, and chronic wounds. Of the proteolytic enzymes , MMPs have received the most attention with regard to wound healing. MMPs appear to be important in acute wound healing. Differences exist between th e amounts, timing, and distribution of MMPs and their inhibitors (tissue in hibitor of metalloproteinases [TIMPs]) in acute and chronic wounds. This su ggests that this imbalance may be important in the development and duration of chronic wounds. In fact, alteration of the MMP/TIMP ratio changes with the healing of chronic wounds. Therapies used to treat chronic wounds may i mpact upon MMPs and their inhibitors, and attention to alterations of MMPs with therapy may be an important endpoint. Among those therapies that likel y impact MMPs is the use of nanocystalline silver dressings. Animal studies have shown that nanocystalline silver dressings alter MMP expression. In t his paper we will review MMPs, the role of MMPs in wound healing, and prese nt preliminary data of the ability to alter MMP expression in chronic human wounds.