Polypropylene and polypropylene/polyglecaprone (Ultrapro®) meshes in the repair of incisional hernia in rats

COMPARATIVE ANALYSIS OF TISSULAR RESPONSE AFTER ABDOMINAL WALL REPAIR USING POLYPROPYLENE MESH AND BOVINE PERICARDIUM MESH

BACKGROUND

The use of polypropylene meshes for surgical repair of the abdominal wall contributes to a reduction of the of recurrence rates of hernias or defects. However, its intra-abdominal use comes along with the formation of adhesions and several complications. The study and the search for alternative materials, including bovine pericardium, have been regarded as an option for the correction and treatment of resulting hernias with better adaptations and effectiveness.

AIM

Evaluating the inflammatory process of the bovine pericardium in comparison with the inflammatory process of synthetic polypropylene mesh.

METHOD

Bovine pericardium mesh and polypropylene mesh were placed, both on the same animal. The first group had the mesh removed for analysis on day 20, and the second group on day 40. The variables congestion, granulation, giant cells, necrosis, acute inflammation, chronic inflammation and collagen were analyzed.

RESULTS

All variables were found in greater numbers as a response to the polypropylene mesh, except for the collagen, which, on day 40, was greater in response to the bovine pericardium mesh.

CONCLUSION

The data in this study suggest that there is less inflammatory reaction in response to bovine pericardium mesh when compared to polypropylene mesh.

Evaluation of In Vivo Adhesion Properties of New Generation Polyglactin, Oxidized Regenerated Cellulose and Chitosan-Based Meshes for Hernia Surgery

Introduction

Composite meshes coated with anti-adhesive barriers have been developed by taking advantage of the robustness of polypropylene meshes for use in hernia repair. We aimed to evaluate the effects of composite meshes containing polyglactin, polycaprolactone, oxidized regenerated cellulose and chitosan on the adhesion formation.

Methods

Forty-two Sprague Dawley male rats were divided into six groups of seven rats according to the content of the meshes used. A defect was created on the right abdominal wall of the rats and an oval composite mesh of 2 cm in diameter was placed over the defect and fixed. The rats were sacrificed under anesthesia on the 7th postoperative day. Macroscopic and histopathological examination was performed and the incorporation of the mesh with the abdominal wall and the presence of intraabdominal adhesions were evaluated.

Results

When the macroscopic findings of the rats were evaluated, there was a statistically significant difference between the rat groups in terms of the distribution of peritoneal adhesion scores (p<0.05). There was no statistically significant difference between the rat groups in terms of the distribution of inflammation, fibrosis and macrophage levels (p>0.05).

Conclusion

It was evaluated that the development of intraabdominal adhesion and the strength of adhesion decreased when biocompatible adhesion barriers with anti-adhesive properties such as oxidized regenerated cellulose and chitosan were used in the structure of composite meshes used in hernia repair. Hemostatic and antibacterial properties of these substances are promising to create the ideal mesh.

Evaluating tissue-engineered repair material for pelvic floor dysfunction: a comparison of in vivo response to meshes implanted in rats

INTRODUCTION AND HYPOTHESIS

Achieving better anatomic restoration and decreasing the associated complications are necessary for material repair of pelvic floor dysfunction (PFD). This study was aimed to investigate host response to tissue-engineered repair material (TERM) in rat models by comparing different materials and study the changes in biomechanical properties over time.

METHODS

TERM was constructed by seeding adipose-derived stem cells (ADSCs) on electrospun poly(L-lactide)-trimethylene carbonate-glycolide (PLTG) terpolymers. The TERM, PLTG, porcine small intestine submucosa mesh (SIS), and polypropylene (PP) (n = 6 / group per time point) were implanted in rats for 7, 30, 60, and 90 days. Hematoxylin-eosin and Masson's trichrome staining were used to assess the host response, and mechanical testing was used to evaluate the changes in biomechanical properties.

RESULTS

In vivo imaging showed that the ADSCs were confined to the abdominal wall and did not migrate to other organs or tissues. The TERM was encapsulated by a thicker layer of connective tissue and was associated with less reduced inflammatory scores compared with PLTG and PP over time. The vascularization of the TERM was greater than that with PP and PLTG over time (p < 0.05) and was greater than that with SIS on day 90. The ultimate tensile strain and Young's modulus of the PP group showed the greatest increases, and the TERM group followed on day 90.

CONCLUSIONS

This TERM achieved better host integration in rat models and better biomechanical properties, and it may be an alternative material for PFD.

In Vivo Evaluation of a Pectin-Honey Hydrogel Coating on Polypropylene Mesh in a Rat Model of Acute Hernia

Investigations about ventral hernia repair are focused on improving the quality, resistance, and biocompatibility of mesh. This study compared plain polypropylene mesh with a pectin-honey hydrogel-coated polypropylene mesh in an acute hernia model in rats. Forty Wistar rats, randomly assigned to two groups, were submitted to laparotomy, and a 1 cm × 2 cm fascial defect was created, centered on the midline. Uncoated (group C) or coated mesh (group T) was inserted in an inlay fashion to repair the defect. After 30 days, the rats were euthanized, and the presence of adhesions to the mesh was macroscopically evaluated. Histology and measurement of COX-2 as tissue inflammation markers were used to assess fascia tissue healing. Grades of adhesion were not different between groups. Histological score and COX-2 expression were not significantly different between groups, except for the higher inflammatory response demonstrated in group T. The pectin-hydrogel coated mesh could not reduce adhesion formation compared to uncoated polypropylene mesh but improved peritoneal regeneration and tissue healing.

Comparative study of peritoneal adhesions after intraperitoneal implantation in rats of meshes of polypropylene versus polypropylene/polyglecaprone versus polyester/porcine collagen

PURPOSE

To Compare the extent and intensity of adhesions formed between the intra-abdominal organs and the intraperitoneal implants of polypropylene mesh versus polypropylene/polyglecaprone versus polyester/porcine collagen used for correction of abdominal wall defect in rats.

METHODS

After the defect in the abdominal wall, thirty Wistar rats were placed in three groups (ten animals each) for intraperitoneal mesh implant: polypropylene group, polypropylene/polyglecaprone group, and polyester/porcine collagen group. The macroscopic evaluation of the extent and intensity of adhesions was performed 21 days after the implant.

RESULTS

The polypropylene group had a higher statistically significant impairment due to visceral adhesions (p value = 0.002) and a higher degree of intense adherence in relation to polypropylene/polyglecaprone and polyester/porcine collagen groups (p value<0.001). The polyester/porcine collagen group showed more intense adhesions than the polypropylene/polyglecaprone group (p value=0.035).

CONCLUSIONS

The intraperitoneal implantation of polypropylene meshes to correct defects of the abdominal wall caused the appearance of extensive and firm adhesions to intra-abdominal structures. The use of polypropylene/polyglecaprone or polyester/porcine collagen tissue-separating meshes reduces the number and degree of adhesions formed.

Sublay repair results in superior mesh incorporation and histological fibrogenesis in comparison to onlay and primary suture in an experimental rat model

PURPOSE

To compare adhesion scores, repair strength and histological findings among sublay, onlay and primary repair incisional hernioplasty techniques. Surgical repairs were employed directly on healthy animals, without previous hernia induction, to avoid confounding factors related to hernia development.

METHODS

Forty Wistar rats were divided into four groups, control, simulation, onlay and sublay. After 42 days, adhesion intensity, tensile strength of the abdominal wall and anatomopathological histological substrate were compared.

RESULTS

SL group presented greater adhesion scores (p < 0.0001), higher tensiometric (p < 0.0001), and was characterized by more histiocytes, mononuclear cells, macrovacuolar granulomas and type I collagen on histological analysis. Pearson correlation between adhesions and tensiometry, and between tensiometry and neocollagenization showed a strong positive association (r = 0.8905 and 0.6757, respectively in SL group, p < 0.05).

CONCLUSION

Mesh positioning in sublay compartment was followed by increased adhesion development and provides a stronger mesh-tissue attachment, in addition, resulted in a different histological profile of the inflammation/repair substrate. The intensity of these findings was directly correlated, suggesting they could be the result of a common biological phenomenon. Our findings indicate that mesh placement following the retromuscular technique generates a superior repair response, and give clues to a better understanding of the superiority of sublay repair in achieving lower recurrence rates. Characterization of the cellular and molecular elements responsible for the superiority of this technique is in our view an essential prerequisite aiming for improvements in the therapeutic options for the treatment of this disease.

Pro - inflammatory cytokines and metalloproteinase activation in polypropylene mesh implant in rat subcutaneous tissue

AIMS AND OBJECTIVES

Polypropylene meshes have been increasingly adopted for correction of pelvic organ prolapse due to its lower recurrence rate when compared to surgeries without meshes. The study of the interaction of these materials with the host tissue may contribute to the development of materials with best biocompatibility and, consequently, less complication rates.

MATERIALS AND METHODS

The present study compares the inflammatory reaction of standard-weight (SW) and lightweight (LW) meshes (72 g/m216g/m2 respectively), implanted in the abdomen of 20 adult rats, which were euthanized in four or 30 days. Quantification of pro-inflammatory markers, IL-1 and TNF-α, and of metalloproteinases, MMP2 and MMP3, were carried out through immunohistochemistry with AxioVision ® software.

RESULTS

There were no significant differences in the quantification of IL-1 and TNF-α in LW versus SW meshes. However, IL-1 quantification increased along time (30 days >4 days, p=0.0269). Also, MMP-2 quantification was similar to SW and LW and both presented a significant increase along time (30 days >4 days, p < 0.0001). MMP-3 quantification also showed no difference between the SW and LW groups, but increased along time (30 days >4 days, p=0.02).

CONCLUSIONS

Mesh's density did not influence the quantification of pro-inflammatory cytokines IL-1 and TNF-α and metalloproteinases 2 and 3. The increased expression of IL-1, MMP-2 and MMP-3 over time could represent a longstanding inflammatory response after PP mesh implantation. Possibly, the occurrence of adverse events following PP prosthetic implants can be influenced by other factors, not solely related to the amount of implanted material.

Comparative study of Polypropylene versus Parietex composite®, Vicryl® and Ultrapro® meshes, regarding the formation of intraperitoneal adhesions

PURPOSE

To compare the polypropylene mesh (Marlex®) to Vicryl®, Parietex composite® and Ultrapro® meshes to assess the occurrence of adhesions in the intraperitoneal implantation.

METHODS

Sixty Wistar rats were allocated into three groups: PP+V, in which all the animals received a polypropylene and a Vicryl® mesh; PP+PC, with the implantation of polypropylene and Parietex composite® meshes and PP+UP, in which there was implantation of polypropylene and Ultrapro®. Macroscopic analysis was performed 28 days later to assess the percentage of mesh area affected by adhesion.

RESULTS

in the PP+ V group, the Vicryl® mesh showed lower adhesion formation (p=0.013). In the PP+PC, there were no differences between polypropylene and Parietex composite® (p=0.765). In the PP+UP group, Ultrapro® and polypropylene meshes were equivalent (p=0.198) .

CONCLUSION

All the four meshes led to adhesions, with the Vicryl® mesh showing the least potential for its formation.

Ventral abdominal wall defect correction in rats with contaminated meshes

PURPOSE:

To investigate whether there is a difference between Marlex(r) and Dynamesh PP-light Marlex(r) meshes, in the abdominal wall defect correction, on rats in contaminated surgical site.

METHODS:

Twenty-eight Wistar rats were divided into two groups of 14, and four subgroups of seven animals. All subgroups underwent similar surgical procedure. One group received the mesh Marlex(r) and the other Dynamesh PP-light(r) for correction of the defect. Before implanting, the meshes went through a contamination process, on which was used standard solution containing 10 UFC of Escherichia coli. Fragments of the animal's abdominal wall received macroscopic, microscopic and microbiological analysis.

RESULTS:

There was no statistical significance in the analysis of macroscopic variables. Accentuated inflammatory process was shown in all subgroups. The foreign body type reaction was mild in all subgroups, except Dynamesh(r)-14, which was moderate with no statistical significance. The microbiological analysis of the meshes was also similar between the subgroups.

CONCLUSION:

There was no difference between the meshes of Marlex(r) and Dynamesh PP-light(r) in the ventral abdominal wall defect correction on rats in contaminated surgical site.

In vivo response to polypropylene following implantation in animal models: a review of biocompatibility

INTRODUCTION AND HYPOTHESIS

Polypropylene is a material that is commonly used to treat pelvic floor conditions such as pelvic organ prolapse (POP) and stress urinary incontinence (SUI). Owing to the nature of complications experienced by some patients implanted with either incontinence or prolapse meshes, the biocompatibility of polypropylene has recently been questioned. This literature review considers the in vivo response to polypropylene following implantation in animal models. The specific areas explored in this review are material selection, impact of anatomical location, and the structure, weight and size of polypropylene mesh types.

METHODS

All relevant abstracts from original articles investigating the host response of mesh in vivo were reviewed. Papers were obtained and categorised into various mesh material types: polypropylene, polypropylene composites, and other synthetic and biologically derived mesh.

RESULTS

Polypropylene mesh fared well in comparison with other material types in terms of host response. It was found that a lightweight, large-pore mesh is the most appropriate structure.

CONCLUSION

The evidence reviewed shows that polypropylene evokes a less inflammatory or similar host response when compared with other materials used in mesh devices.