Page 268 - Prevention and Treatment of Incisional Hernia- New Techniques and Materials

Chapter 13
cannot phagocytose this synthetic biomaterial, leading to the formation of giant cells situated at the biomaterial surface10.
In a contaminated environment macrophages adapt to an M1 phenotype(9), needed for control of the acute infection by phagocytosis. However, prolonged M1 phenotype of macrophages can lead to tissue damage, and may compromise the integration of the material in the body by the release of in ammatory cytokines(10). Therefore, the foreign body reaction is altered in a contaminated environment.
New biomaterials should be developed for use in an environment where the risk of contamination of the biomaterial is high. Biological materials, such as collagen-based biomaterials processed from human or porcine dermis, are thought to be tolerated in an environment at high risk of contamination and have a low postoperative complication rate(11, 12). Biomaterials with low actual surface area, such as mono lament biomaterials, were well tolerated in a contaminated eld in an experimental study2, and in several clinical studies have been associated with fewer postoperative infections(13, 14). However, there is no consensus yet, and only a few comparative studies13,14 are available. In a recent study15 employing an experimental rat model, the foreign body reaction in rats was biomaterial-dependent in a contaminated environment. Some biomaterials had poor incorporation into the abdominal wall with a high infection rate, whereas others, such as mono lament polypropylene biomaterials, had good incorporation into the abdominal wall and a low in ammatory reaction(15).
The aim of this study was to investigate the reaction of macrophages to biomaterials in an environment at risk of contamination. First, the phenotype of macrophages surrounding a mono lament polypropylene biomaterial was analysed in vivo, as this material has been shown previously to induce the mildest foreign body reaction(15). Second, the macrophage phenotype and reaction were characterized in more detail in an in vitro model. In this model bacterial contamination was simulated, thereby permitting comparison of the macrophage reaction in a contaminated and a clean environment. Contamination was simulated using a combination of lipopolysaccharide (LPS) and interferon (IFN) γ, and the macrophage reaction was studied by measuring a panel of proteins indicative of the macrophage phenotype.
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