In vitro and in vivo characterization of a fully resorbable and composite surgical mesh

Abstract

Fully resorbable and composite synthetic meshes are intended to provide advantages over nonabsorbable synthetic meshes, such as minimization of visceral adhesions and improved biocompatibility, but the inflammatory response to these materials has not previously been fully characterized. We compared resorbable and composite synthetic meshes using in vitro characterization and evaluated the host response in a nonhuman primate acute abdominal wall defect. After a 2-week in vitro incubation, resorbable synthetic mesh mechanical strength decreased to 0.12 ± 0.09 N (0.25% of initial strength), which preceded acidification and a fractured morphology at 1 month. The composite synthetic mesh strength decreased to 10.0 ± 3.2 N (41.1% of initial strength), coincident with morphological changes. In vivo, resorbable synthetic mesh elicited an intense yet transient foreign-body response, with macrophages and myofibroblasts persisting through 3 months of implantation. At 6 months, resorbable synthetic mesh was undetectable and the mesh–host tissue interface strength (14.7 ± 7.9 N) was equivalent to that of primary repair (21.4 ± 4.9 N). The composite synthetic mesh elicited a significant foreign-body response following 1 month of implantation. By 3 months, the composite synthetic mesh resorbable films had fully degraded, with foreign-body reaction localized to polypropylene fibers. By 6 months, macrophages had surrounded these polypropylene fibers, with a myofibroblast-positive capsule encircling a macrophage-rich layer. Resorbable and composite synthetic meshes may ultimately not be the most ideal biomaterials in situations where the biological response is expected to lead to a regeneration of host soft tissues.