EARLIER STUDIES have shown that incubated mixtures of autologous whole blood and either trypsin or pancreatic enzymes contain a highly toxic digestion product.1, 2 Local injections of this material cause intense inflammatory responses regardless of the tissue involved.
Enzyme-digested blood appears to exert its necrotizing properties by producing severe vasculitis.1 Smaller arteries and veins are involved in an intense inflammatory reaction which appears to originate in the external layers and progress through the vessel wall. The adventitia undergoes coagulation necrosis; muscular fibers of the media are separated by edema fluid and infiltrated with inflammatory cells. The internal elastic membrane is swollen and often disrupted, and endothelial cells become pyknotic. Thrombi develop in the venous circulation, and the continuity of smaller vessels may be destroyed. These vascular changes are accompanied by an extensive loss of serosanguineous fluid into the intercellular spaces. Involved vessels are surrounded by a halo