The Effects of Pectin-Honey Hydrogel in a Contaminated Chronic Hernia Model in Rats

Abstract

Incisional hernia is a frequent complication after abdominal surgery. A previous study on rats evaluated the use of a Pectin-Honey Hydrogel (PHH)-coated polypropylene (PP) mesh for the healing of acute hernias. However, there are no studies investigating the use of PHH in association with PP mesh in chronic contaminated hernia. The aims of this study are to assess the effectiveness of PHH in promoting abdominal hernia repaired with PP mesh and in counteracting infection. Twenty Sprague Dawley male rats were enrolled and a full thickness defect was made in the abdominal wall. The defect was repaired after 28 days using a PP mesh, and a culture medium (Tryptone Soy Broth, Oxoid) was spread onto the mesh to contaminate wounds in both groups. The rats were randomly assigned to a treated or untreated group. In the treated group, a PHH was applied on the mesh before skin closure. At euthanasia-14 days after surgery-macroscopical, microbiological and histopathological evaluations were performed, with a score attributed for signs of inflammation. An immunohistochemical investigation against COX-2 was also performed. Adhesions were more severe (p = 0.0014) and extended (p = 0.0021) in the untreated group. Bacteriological results were not significantly different between groups. Both groups showed moderate to severe values (score > 2) in terms of reparative and inflammatory reactions at histopathological levels. The use of PHH in association with PP mesh could reduce adhesion formation, extension and severity compared to PP mesh alone. No differences in terms of wound healing, contamination and grade of inflammation were reported between groups.

Keywords: adhesion; bacterial contamination; hernia healing; pectin–honey-hydrogel; polypropylene mesh; rats.

Figure 1

Details related to the percentage of adhesions reported in Group T and in Group C.

Figure 2

Presence of adhesions between linea alba and organs in three rats from Group C. The first figure on the left depicts the adhesion between the linea alba and the bladder. In the middle figure, the adhesion between the linea alba and intestine is reported, while the last figure shows the adhesion between the abdominal wall and the liver.

Figure 3

Rat abdominal wall tissues histological section. Multifocal granulomas (asterisk) are present (inflammatory response score 2) and thin layer of fibrosis (arrow-tissue maturation score 2). Hematoxylin–eosin staining; 40× magnification.

Figure 4

Rat abdominal wall tissue histological sections. Arrow indicates dense granular tissue with fibroblasts and inflammatory infiltrates (score 3 of inflammatory reaction in host tissue). Hematoxylin–eosin staining; 40× magnification.

Figure 5

Rat abdominal wall tissue histological sections. Mass of inflammatory cells without permeating connective tissue in host tissue (score 4). Hematoxylin–eosin staining; 40× magnification.

Figure 6

Abdominal wall tissue immunohistochemical staining against COX-2. a: 25–50% of COX-2 immunopositive inflammatory cells (score 2) with a moderate intensity (score 2), 400× magnification; b: 51–100% of COX-2 immunopositive cells (score 3) with a strong intensity (score 3), 200× magnification. DAB chromogen, hematoxylin counterstain.

Figure 7

Abdominal wall tissue immunohistochemical staining against COX-2. There are 51–100% of COX-2 immunopositive inflammatory cells (score 3) with a strong intensity (score 3), 200× magnification. DAB chromogen, hematoxylin counterstain.

Figure 8

Creation of abdominal defect on skin, linea alba and peritoneum.

Figure 9

(A): PP mesh inserted on the linea alba to ensure the hernia repair; (B): contamination of the PP mesh with 0.1 mL of bacteria broth; (C): PHH inserted on the PP mesh before skin closure in Group T; (D): skin closure with skin staples.

Figure 10

Presence of hernial defect evaluated before reparative surgery, left lateral view.