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Background: Currently, absorbable meshes are used as temporary closure in case of laparostoma. Unfortunately the multifilament polyglycolic acid (PG) meshes with small pores reveal little elasticity acting rather as a fluid barrier than permitting drainage of intra-abdominal fluids. Therefore, a new mesh was constructed of absorbable polydioxanon monofilaments (PDS) with increased porosity and longer degradation time., Material and Methods: For evaluation of the tissue response the new PDS mesh was implanted as abdominal wall replacement in each five rats for 7, 21, or 90 days, respectively, and compared to a PG mesh. Histological analysis included HE staining with measurement of the size of the granuloma and immunoshistochemistry for TUNEL, Ki67, TNF-R2, MMP-2, YB1, FVIII, gas6, AXL. Parameters for neovascularization and nerve ingrowth were analyzed., Results: The inflammatory and fibrotic tissue reaction is attenuated with PDS in comparison to PG, e.g., the size of the granuloma was smaller with less cell turnover, and less remodeling as represented by, e.g., reduction of apoptosis, expression of MMP-2, or TNF-R2. The number of ingrowing nerves and vessels explored via AXL, gas6, and factor VIII was increased in the PDS mesh., Conclusion: The results from the present investigation showed that a mesh can be constructed of monofilament PDS that induce significant less inflammatory and fibrotic reaction, however permits fluid drainage and preserves elasticity.

Placement of mesh is involved in 75-80% of hernia operations. It is known that an exaggerated foreign body reaction leads to clinical complications. To further improve patients outcome using biotechnological agents targeted against tumor necrosis factor-alpha (TNF-alpha) or interleukin-6 (IL-6), a study was conducted investigating the impact of cytokine knockout on mesh integration. Sixty mice were used: C57BL/6 wild type control, C57BL/6-IL-6 interleukin-6 knockout, C57BL/6-Tnfrsf1a knockout of TNF-alpha receptor 1, and C57BL/6-Tnfrsf1b knockout of TNF-alpha receptor 2. Standard polypropylene mesh was implanted subcutaneously for 7, 21, and 90 days. The inflammatory and connective tissue formation was characterized by diameter of inner cellular infiltrate and outer fibrous capsule of the foreign body granuloma, and by quantity (collagen/protein ratio) and quality (collagen type I/III ratio) of collagen formation. Microscopic investigation of the mesh/host-tissue interface showed typical formation of foreign body granulomas. Ninety days after implantation none of the knockout strains showed significant differences compared to the control group investigating amount of inflammatory and connective tissue formation. Analyzing the quantity of filamentary collagen deposition the C57BL/6-IL-6 group showed significant lowered values compared to the control group 90 days after implantation. In all groups collagen type I/III ratio increased over time as an indicator for maturation of the surrounding collagen formation. However, no difference was found comparing strains at the end of the observation period. The results support the notion that wound healing is affected by cytokine deficiency. However, a desirable reduced amount of inflammatory tissue formation as well as an increased collagen type I/III ratio due to cytokine knockout could not be observed.