Page 266 - Prevention and Treatment of Incisional Hernia- New Techniques and Materials

Chapter 13
Abstract
Background
Macrophages play an important role in the reaction to biomaterials, which sometimes have to be used in a surgical eld at risk of contamination. The macrophage phenotype in reaction to
biomaterials in an in ammatory environment was evaluated in both an in vivo and in vitro setting.
Methods
In the in vivo setting, polypropylene (PP) biomaterial was implanted for 28 days in the contaminated abdominal wall of rats, and upon removal analysed by routine histology as well as immunohistochemistry for CD68 (marker for macrophages), inducible nitric oxide synthase (iNOS – a marker for proin ammatory M1 macrophages) and CD206 (marker for anti-in ammatory M2 macrophages). For the in vitro model, human peripheral blood monocytes were cultured for 3 days on biomaterials made from PP, collagen (COL), polyethylene terephthalate (PET) and PET coated with collagen (PET+COL). These experiments were performed both with and without lipopolysaccharide and interferon γ stimulation. Secretion of both M1- and M2-related proteins was measured, and a relative M1/M2 index was calculated.
Results
In vivo, iNOS- and CD206-positive cells were found around the bers of the implanted PP biomaterial. In vitro, macrophages on both PP and COL biomaterial had a relatively low M1/M2 index. Macrophages on the PET biomaterial had a high M1/M2 index, with the highest increase ofM1 cytokines in an in ammatory environment. Macrophages on the PET+COL biomaterial also had a high M1/M2 index.
Conclusion
Macrophages in an in ammatory environment in vitro still react in a biomaterial-dependent manner. This model can help to select biomaterials that are tolerated best in a surgical environment at risk of contamination.
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