Activation and control of complement, inflammation, and infection associated with the use of biomedical polymers

It is generally acknowledged that artificial biomaterials are much less imm unologically active than transplants or tissue derived biomaterials. Howeve r, activation of both the coagulation cascade and the complement system is a common occurrence when human blood is exposed to biomaterial surfaces dur ing extracorporeal procedures, such as renal hemodialysis or cardiopulmonar y bypass. Both individual and collective activation of these cascades often produce local and systemic effects. A number of complement activation prod ucts function as the mediators of inflammation. They serve as ligands for s pecific receptors on polymorphonuclear leukocytes, monocytes, macrophages, mast cells, and other cells. Such an interaction leads to induction of cell ular responses in adhered cells, including release of oxidative products, l ysosomal enzymes, or both, which often contribute to a number of pathologic conditions. Most pathogens invading the human body are attacked by the imm une system directly following entry, especially when they are in contact wi th blood. However, bacteria and parasites have developed a large number of specific strategies to overcome immune defense among others by avoiding eit her recognition or eradication by complement. In this aspect, of concern ar e several microorganisms responsible for formation of antibiotic resistant biofilms on biomaterial surfaces, namely Staphylococcus epidermidis, Staphy lococcus aureus, and Pseudomonas aeruginosa.