A critical review of biologic mesh use in ventral hernia repairs under contaminated conditions

Department of Surgery, University of California, 513 Parnassus Avenue, S-301, San Francisco, CA, 94143-0104, USA.
Hernia (Impact Factor: 2.09). 01/2013; 17(1). DOI: 10.1007/s10029-012-1037-8
Source: PubMed

ABSTRACT PURPOSE: We used an evidence-based approach to determine whether the promotions and claims of superiority of biologic mesh over synthetic mesh use in ventral hernia repairs (VHRs) under contaminated conditions were sound and valid. METHODS: We searched the Medline database to specifically identify review articles relating to biologic mesh and VHR and critically reviewed these studies using an evidence-based approach. RESULTS: For the past 45 years, four clinical reviews and one systematic review have included biologic meshes as part of a larger discussion on available prosthetics for VHR. All reviews supported biologic mesh use, especially in the setting of contaminated fields. Yet, the primary literature included in these reviews and served as the basis for these conclusions consisted entirely of case series and case reports, which have the lowest level of evidence in determining scientific validity. Furthermore, the FDA has neither cleared nor approved this particular use. CONCLUSIONS: The cumulative data regarding biologic mesh use in VHRs under contaminated conditions does not support the claim that it is better than synthetic mesh used under the same conditions. The highly promoted and at least moderately utilized practice of placing biologic mesh in contamination is being done outside of the original intended use, and a re-evaluation of or possible moratorium on biologic mesh use in hernia surgery is seriously warranted. Alternatively, an industry-sponsored national registry of patients in whom ventral hernia repairs involved biologic mesh would substantively add to our understanding regarding how these intriguing biomaterials are being used and their overall clinical efficacy.

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    ABSTRACT: Background Macrophages play an important role in the reaction to biomaterials, which sometimes have to be used in a surgical field at risk of contamination. The macrophage phenotype in reaction to biomaterials in an inflammatory 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 proinflammatory M1 macrophages) and CD206 (marker for anti-inflammatory 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 fibres 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 of M1 cytokines in an inflammatory environment. Macrophages on the PET+COL biomaterial also had a high M1/M2 index. Conclusion Macrophages in an inflammatory 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. Surgical relevance Biomaterials in an environment at risk of contamination are often not tolerated owing to a high risk of postoperative infection, which may ultimately lead to removal of the biomaterial. An in vitro model with primary human macrophages was used to provide insight into the acute reaction of macrophages to a biomaterial in an inflammatory environment simulated with lipopolysaccharide and interferon γ. The reaction of macrophages in such an inflammatory environment was still biomaterial-dependent. This in vitro model can be used to study the reaction of macrophages to different biomaterials in an inflammatory environment in more detail, and thereby help to select biomaterials that are tolerated best in a surgical environment at risk of contamination.
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    ABSTRACT: Biologic meshes are being used with increasing frequency to repair contaminated abdominal wall defects despite high long-term recurrence and infection rates associated with their use. Recent clinical reports describing the success of lightweight, macroporous synthetic meshes in contaminated ventral hernia repairs have led some surgeons to challenge the belief that synthetics are contraindicated in contaminated fields. We aimed to determine whether a frequently used biologic mesh (Strattice(TM)) is more resistant to bacterial colonization than macroporous synthetic mesh (Parietex(TM) Progrip(TM)) after inoculation with two common pathogens.
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    ABSTRACT: Surgical treatment of incisional hernia includes implantation of a mesh. The use of synthetic grafts in contaminated fields results in an increased risk of infection. In these cases a potential advantage is described for biological repair material. Evidence for this problem is lacking; therefore, we initiated a survey among surgeons in Germany concerning this question.