Why do skin grafts fail?

Fibrin is shown to be the agent responsible for the adherence of biological dressings and of autografts to wounds. Its presence is associated with graft success, and its absence with graft failure. The results suggest that the deposition of fibrin provides the basis for the anti-bacterial actions of biological dressings and for the sterilization of the wound under adherent autografts. The total number of bacteria per gram of tissue in the wound, though important, is not critical to the result of skin grafting. The mechanism by which different organisms cause grafts to fail is by the production of plasmin and proteolytic enzymes which dissolve the important fibrin scaffold--thus ensuring their own survival. Thus, it is the levels of these (and the numbers of organisms efficient in producing them) which cause success or failure of applied skin grafts.