Discussion: Adipose Tissue–Derived Stem Cells Enhance Bioprosthetic Mesh Repair of Ventral Hernias

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Rather than evaluate the entire article as is customary, I will take the liberty to analyze and discuss the first paragraph of the introduction. The mantra chanted in practically every article on bioprosthetic meshes is the concept that synthetic meshes cause adhesions, infections, and enterocutaneous fistulas. The implied message is that they should be avoided. An article over 20 years old is cited as the reference to these complications. As a point of academic discussion, how valid is this with modern-day meshes and techniques?Historically, Stone and Fabian described the use of prosthetics for the reconstruction of problematic full-thickness defects of the abdominal wall. Over a 20-year period, a large number of patients in dire situations were closed with polypropylene synthetic meshes to prevent postoperative evisceration. These were patients with open abdomens, sepsis, distention, trauma, and large tumor excisions. Not surprisingly, placing synthetics on swollen bowel was associated with extrusions, infections, and adhesions. Fistulas were noted in 13 of 165 cases, and there was an overall mortality rate of 39 percent. After granulation had grown through the pores of the mesh, the synthetics were covered with skin grafts or flaps. Prolene (Ethicon, Somerville, N.J.) mesh was recommended over the weave associated with Marlex (Bard, Cranston, R.I.) mesh for its “pliability.” Full-thickness flaps were recommended as cover rather than skin grafts.1 In a similar series of patients with bowel swelling and a 50 percent fistula rate, Voyles et al. stressed the avoidance of skin grafts on granulated polypropylene and the need to avoid prolonged dressing changes.2 These reports represent the worst possible results using mesh—large sheets of mesh used in inflamed and contaminated fields with bowel injury and without adequate soft-tissue cover.3An excellent comparison article by Vrijland et al. in 2000 reported on patients treated from 1982 to 1998. They used polypropylene to repair hernias rather than to reconstruct the abdominal wall in the prevention of evisceration. There were no fistulas in 136 patients with a 34-month follow-up despite mesh being placed directly on bowel. In the same article, their meta-analysis of six articles with 567 patients reported a fistula rate of 0.5 percent and an infection rate of 6 percent, again despite mesh being placed directly on bowel.4 The difference in their results from those of Stone et al. and Voyles et al. is no doubt patient selection—the mesh in these cases was placed electively in the absence of contamination and inflammation, and with adequate overlying soft-tissue cover.Potential improvements in prosthetic mesh and the development of bioprosthetic meshes have led to a bewildering number of studies comparing one product to its competitor. These investigations were driven, no doubt, by the development of laparoscopic hernia repair that requires mesh to be placed directly on the bowel. Returning to the central question initially raised by the 1980 articles, can these materials with or without special coatings be placed on bowel without causing unacceptable adhesions, infections, extrusions, and fistulas? If not, are bioprosthetic meshes then the solution? I will break the studies down into various analyses of the meshes.ADHESION FORMATIONProsthetic mesh has been shown to incite a fibroblastic response. Typically, the percentage surface area of the mesh with adherent omentum or bowel in test animals is measured a standard time after implantation. Comparisons between different types of mesh imply that standard polypropylene (Marlex) incited significantly more adhesions than did mid-weight polypropylene (Proceed; Ethicon) or expanded polytetrafluoroethylene (DualMesh; W. L. Gore and Associates, Flagstaff, Ariz.).

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