Page 281 - Prevention and Treatment of Incisional Hernia- New Techniques and Materials

Macrophages in a contaminated environment
the thin collagen layer(22). A proin ammatory reaction was induced by the macrophages on PET+COL, even in a non-stimulated environment. When this environment was compared with an in ammatory environment in vitro, only a slight further increase in proin ammatory protein production was observed. This indicates that the PET+COL material itself has a great in uence on the reaction of macrophages.
In a previous study16, the M1/M2 index in a sterile environment was analysed in vitro. Most interestingly, the present data indicate that the macrophage response remains biomaterial-speci c even in an environment with simulated contamination. When comparing sterile and contaminated environments, the largest di erences were observed for TNF-α production. TNF-α is an acute-phase protein, and reacts quickly in the present in vitro system. However, this does not indicate that the fourfold increases in MCP-3 or the threefold increases in IL-6 are less relevant, as these factors might have a di erent potency or kinetics.
In vivo there is a great di erence between multi lament and mono lament biomaterials, as the former allow for more cells to attach and ll the biomaterial. Mono lament biomaterials are less prone to infection because they provide fewer niches for bacterial in ltratration2,3. In the present study, mono lament biomaterials were not tested in the in vitro system owing to the low number of macrophages attaching to these in comparison with multi lament biomaterials.
The variation between macrophages isolated from di erent donors is not unexpected because it is known from clinical practice that patients respond di erently to biomaterials. However, variations between the samples from one donor were also observed, which can be explained by the fact that monocytes are a heterogeneous population with di erent sensitivities to biomaterials or cytokines. However, taken together, distinct di erences in macrophage reactions to biomaterials were observed.
The present study describes the very acute reaction to biomaterials, with analysis after 3 days of culture. The acute reaction is indicative of the subsequent outcome. It is obvious that the in vivo conditions are more complex than the in vitro situation. Most importantly, this study shows that an in vitro model system can be used to evaluate and simulate the foreign body reaction in an in ammatory environment, which can aid in selecting and developing new biomaterials that are well tolerated under conditions with a high risk of postoperative biomaterial infection.
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