Analysis and Characterization of Biologic Implants

Overview

The purpose of this study is to investigate what happens to biologic mesh in the body over time on a molecular level. To date, it is not known what agents, enzymes, or proteins are interacting at the implantation site that contributes to mesh remodeling and/or degradation. Investigators on this project will identify patients with previously placed mesh who are needing reoperation on the same site and take a biopsy of the mesh during the normal course of surgery. Basic data surrounding the surgical procedure will be collected. The mesh samples will be analyzed for enzymes and proteins and examined histologically for processes that signify remodeling and/or degradation. Control patients will undergo biopsy of abdominal fascia at laparoscopic trocar sites in a manner that will not affect the outcome(s) of their procedure or other risk to the incision site.

Several such biologic meshes have now been developed and marketed for use in hernia repair and soft tissue reconstruction. These biologics include one product derived from porcine intestinal submucosa (SurgisisTM, Cook Medical), another derived from porcine dermis (CollaMendTM, C.R. Bard Inc.) and several others derived from decellularized human dermis, such as AlloDermTM (LifeCell Corp.), AlloMaxTM (C.R. Bard Inc.), and FlexHDTM (Musculoskeletal Transplant Foundation). Although similar in concept and design, each of these biologic meshes is produced in a distinct, proprietary fashion, and different techniques are used by each company in the processing and storage of their respective products. Given that these processing steps are protected industrial intellectual property, rigorous comparison of the performance of each mesh is very difficult. It is expected that certain methods, such as employing or avoiding chemical cross-linking of the ECM proteins, would lead to significant differences in cell migration into, and biochemical remodeling of each individual mesh. These differences may be of particular importance in the scenario of laparoscopic ventral hernia repair, where the mesh is placed in direct apposition to the parietal peritoneum. In this case, if the biologic were to remodel and take on more of the properties of the distensible peritoneum rather than that of the stronger abdominal wall fascia, this could have a significant impact on the long-term strength and durability of the hernia repair. A similar situation could also be foreseen to occur at the esophageal hiatus and/or the site of an intestinal stoma. We feel that it is thus important to study the remodeling processes that these meshes undergo over time and determine if differences in product processing or anatomical position have any effect on mesh incorporation and hernia integrity. Many of these meshes have already been used in human subjects, yet a certain number of these patients are known have suffered hernia recurrences requiring reoperation and removal of some or all of the original mesh prostheses. It is our belief that these biologic explants represent an excellent source of material to study the remodeling process over numerous given time points and at various anatomic locations. We feel it is also important to compare the explanted biologic meshes to "control" tissues, to examine how successfully the biologic meshes are mimicking native tissue at the molecular and histologic level. To eliminate confounding factors, explanted meshes will be compared to biopsies of abdominal wall fascia from patients undergoing non-hernia related surgical procedures.