Doxycycline impacts hernia repair outcomes

Background: Incisional hernias occur commonly in up to 20% of all abdominal operations. Incisional hernia formation has been associated with increased levels of matrix metalloproteinases (MMPs), reduced collagen 1, and increased collagen 3 expression. Doxycycline, a nonspecific inhibitor of MMPs, has been shown to beneficially reduce MMP levels in both cancer and aneurysm models. This study evaluates the impact of doxycycline upon MMP expression, collagen subtypes, and hernia repair distraction forces in an animal model of incisional hernia repair. Materials and methods: Twenty-four Sprague Dawley rats underwent incisional hernia creation and subsequent repair with polypropylene mesh. Animals were administered doxycycline or saline daily beginning 1 d prior to hernia repair and survived for 1, 2, or 4 wk. Serum and tissue were evaluated for MMP content and collagen subtyping utilizing enzyme-linked immunosorbent assay and Western blot. Tensiometric properties of the native abdominal wall after hernia repair were measured with an Instron Corp. (Canton, MA) mechanical testing system. Results: There were no differences in control and experimental groups 1 and 2 wk following hernia repair; 4 wk following hernia repair, doxycycline treated animals demonstrated reduced serum MMP-2 and MMP-9 levels, reduced tissue levels of MMP-2, MMP-3, and MMP-9, and increased collagen 1 to 3 ratios. Distraction forces required to disrupt the hernia repair were increased in the doxycycline treated group compared with controls. Conclusions: Doxycycline administration is associated with improved hernia repair strength with concomitant reduction of MMP levels with increased collagen 1 deposition. Longer term studies are required to better understand the impact of this treatment.