Silver ions, delivered to a wound surface appear to decrease excess surface and matrixs metallo protease (MMP’s) activity. Excess proteinase activity is now considered to be a major cause of impaired healing by destroying new tissue and growth factors. There is an increased expression of MMP’s in a burn wound. This response may well be the mechanism for the clinical observation that pure silver delivery decreases inflammation and wound surface exudate. A silver induced decrease in wound Zinc which is required for MMP activity as well as oxidation of sulfur bonds, would decrease MMP activity. The decrease in zinc is likely due to the silver induced increase in wound metallo thionein, a known binder of zinc.

The control of inflammation and MMP’s is essential as the proteases not only degrade new tissue but also denature growth factors. Natural tissue inhibitors of MMP’s are present but often do not increase sufficiently to counteract an increase in MMP’s. The result is impaired healing.

Silver could be looked at as a form of tissue proteinase inhibitor. In addition, silver increases surface calcium ions possibly via a calmodulin effect. Increased wound calcium increases the rate of wound epithelial proliferation and migration.

The metalloproteinases (MMP’s) are a family of proteases present in wounds for the purpose of breaking down damaged tissue (gelatin is denatured collagen)