Page 273 - Prevention and Treatment of Incisional Hernia- New Techniques and Materials

Macrophages in a contaminated environment
Results
Macrophage phenotype in vivo
The PP biomaterial was well integrated in the surrounding tissues 28 days after implantation into the contaminated abdominal wall of rats. On histological examination, all samples displayed dense tissue surrounding the bres of the biomaterial, with many multinucleated CD206-positive giant cells. iNOS and CD206-positive cells were also observed in this dense layer. In addition, many blood vessels were observed in the connective tissue surrounding the biomaterial (Figure 2).
To investigate the in uence of a biomaterial, samples of abdominal wall tissue from control rats with contamination but without implanted biomaterial were also stained with haematoxylin and eosin, CD68, CD206 and iNOS at 28 days. These samples had no in ltration of lymphocytes and only a few macrophages, some of which were iNOS- or CD206-positive (Figure 2).
Biomaterial-dependent e ect on macrophage phenotype in an in vitro model
LPS and IFN-γ were chosen to simulate bacterial infection in the in vitro model. LPS is a bacterial wall fragment and IFN-γ is known to activate the immune system and macrophages following bacterial infection22. To investigate how macrophages react on biomaterials in this simulated in ammatory environment in vitro, production of IL-1β, IL-6, TNF-α, MCP-3, MIP-1α, IL-1RA, RANTES, MDC and CCL18 was measured. The production of these proteins in an in ammatory environment was compared with that in a non-stimulated environment. Although the in ammatory environment increased the production of most proin ammatory proteins by macrophages, there were still di erences in relation to the tested biomaterials (Figure 3). Macrophages on PET biomaterial induced the biggest increase in proin ammatory proteins. The stimulated versus non-stimulated ratio for anti-in ammatory proteins was approximately 1, indicating no increase in the production of these proteins in an in ammatory environment, except for RANTES, which was produced in greater amounts by macrophages on PET biomaterial in an in ammatory environment (Figure 4).
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