Amniotic Membrane-Coated Polypropylene Mesh for the Repair of Incisional Hernia: An Experimental Study In a Rat Model of Abdominal Wall Defect

Background: Incisional hernia repairs are among common abdominal wall surgeries, can be primarily required or being reconstructed using a synthetic or biological material. Objectives: This study aimed at evaluating intra-abdominal adhesions and incisional site healing after the repair of abdominal wall by fresh amniotic membrane-coated polypropylene mesh in comparison to only polypropylene mesh in an experimental rat study. Methods: The study protocol was approved by Cumhuriyet University Institutional Ethics Committee for Animal Experiments (Sivas-Turkiye, date 24/06/2015). Sixteen pregnant female Wistar-Albino rats (mean weight, 275 g) were anesthetized on the 21st day of pregnancy and a 1-cm area of the abdominal wall was excised. The pregnancy was terminated, emerging amniotic membranes were dissected, and eight pieces of the 1-cm(2) polypropylene mesh were coated with these amniotic membranes without using any suture or adhesive. The polypropylene meshes were sutured on the abdominal wall of eight rats (control group), selected by simple random sampling. For the remaining eight rats, the same procedure was applied with the amniotic membrane-coated polypropylene meshes (experimental group). On the 28th postoperative day, the anterior abdominal wall was opened, and intra-abdominal adhesions were assessed macroscopically by Nair's adhesion scoring system. Strip-shaped biopsy samples were taken from incision lines for histopathological examination. Results: The experimental group had significantly less intra-abdominal adhesions (i.e. Nair's score of 2 to 4) compared to the control group (two and six rats, respectively; P= 0.046), and had significantly lower mean score for polymorphonuclear leukocyte infiltration (P = 0.039), hyperemia (P= 0.039), and epithelialization (P= 0.039). The score for increase in connective tissue (P = 0.018) was significantly higher in the experimental group, and the scores for edema (P= 0.590) and macrophage infiltration (P= 0.590) were similar between the two groups. Conclusions: The use of polypropylene mesh coated with fresh amniotic membrane provides advantage of decreasing postoperative intra-abdominal adhesions along with less inflammation and higher epithelialization after abdominal wall repair surgery.