Lack of identifiable biologic behavior in a series of porcine mesh explants

Abstract

Biologic matrices used in abdominal wall reconstruction are purported to undergo remodeling into connective tissue resembling native collagen. Key steps in that process include inflammatory response at the mesh/tissue interface, cellular penetration, and neovascularization of the matrix, followed by fibroblast proliferation and collagen deposition. We aimed to examine the concept of biologic mesh remodeling/regeneration in a series of explanted porcine biologic meshes. A cohort of patients who underwent removal of porcine biologic mesh was identified in a prospective database. Mesh/tissue samples were analyzed using standard hematoxylin/eosin and Masson's trichrome staining. Main outcome measures included: inflammatory response at the mesh/tissue interface, foreign body reaction (FBR), cellular penetration, neovascularization, and new collagen deposition. All evaluations were performed by a blinded senior pathologist using established grading scales. A total of 14 cases with implant time ranging from 4 to 33 months were identified and analyzed. All meshes were placed as intraperitoneal underlay. There were 7 non-cross-linked and 7 cross-linked grafts. Cross-linked grafts were associated with mild FBR and moderate fibrous capsule formation. Similarly, non-cross-linked grafts had mild-to-moderate FBR and encapsulation. Furthermore, non-cross-linked grafts were associated with no neovascularization and minimal peripheral mesh neocellularization. Cross-linked grafts demonstrated neither neovascularization nor neocellularization. Although no grafts were associated with any quantifiable new collagen deposition within the porcine biologic matrix, minimal biodegradation/remodeling was observed at the periphery of the non-cross-linked grafts only. The biologic behavior of porcine meshes is predicated on their ability to undergo mesh remodeling with resorption and new collagen deposition. In the largest series of human biologic explants, we detected no evidence of xenograft remodeling, especially in the cross-linked group. Although underlay mesh placement and other patient factors may have contributed to our findings, the concept of porcine biologic mesh regeneration does not seem to be prevalent in the clinical setting.