Use of a Rat Model to Study Ventral Abdominal Hernia Repair

Summary

This manuscript describes methods associated with creation and repair of a ventral abdominal wall defect (hernia). This model can be used to study repair strategies such as those that use implanted materials. In this manuscript, repair of the experimental hernia with porcine small intestinal submucosa is presented as an example.

Abstract

Ventral abdominal hernia is a relatively common clinical condition that sometimes requires herniorraphy (surgical repair). The repair of ventral abdominal hernia typically requires implantation of a material to serve as a mechanical bridge across the defect in the abdominal wall. Biomaterials, such as porcine small intestinal submucosa (SIS), also serve as a lattice for cell growth into the implant and can naturally incorporate into the host tissue. Development of such repair materials benefits from use of animal models in which experimental abdominal wall defects are easily created and are amenable to repair in a reproducible fashion. The method offered here describes surgical creation and repair of ventral abdominal hernia in a rat model. When SIS is used to repair an experimental ventral abdominal hernia in this model, it is rapidly incorporated into host tissue within 28 days of implantation. Histologically, incorporation of their implanted material into host tissue is characterized by a robust fibrovascular response. Future refinements and applications of the rat abdominal hernia model may likely involve diabetic and/or obese animals as a means to more closely mimic common co-morbidities of man.

Introduction

Abdominal wall hernia is a commonly encountered clinical issue which may occur as a result of congenital defect, traumatic injury, or failed closure of surgical wounds involving the abdominal wall. Repair commonly involves using an implant to reinforce the abdominal wall, with a reduced rate of recurrence noted in patients treated with an implant compared to those in whom the abdominal wall is simply closed with suture.¹

Surgical hernia repair often requires mechanical bridging of the defect with an implanted material. In this regard, both synthetic and natural materials have been used for hernia repair. Many synthet....

Protocol

The use of animals in this protocol was approved by the University of Notre Dame Institutional Animal Care and Use Committee, followed all regulatory requirements and guidelines, and was conducted in a facility that is accredited by the Association for Assessment and Accreditation of Laboratory Animal Care (AAALAC), International.

1. Selection of Animals

1. Acquire pathogen-free Sprague Dawley rats from a reputable vendor or breeding colony.
   Note: Often, the facility veterinarian or manager can direct the investigator to appropriate sources. Rats of approximately 250 g body weight are suitable for this procedure.
2. O....

Results

By 28 days after implantation, SIS typically demonstrates good incorporation into host tissue (Figure 2). In most cases, there is residual SIS apparent, though the tissue must often be explored to identify the implanted material. Histological analyses confirmed the gross pathological observations, illustrating good tissue incorporation with primarily fibrovascular tissue and very little residual SIS noted (Figure 3). These results demonstrate the utility .......

Discussion

Materials for the repair of ventral abdominal hernia are of great interest, particularly those that provide an initial mechanical bridge and are then able to incorporate into host tissue. In this regard, a variety of materials have been investigated, including SIS, porcine acellular dermal matrix, and porcine pericardium.^6,7 These materials represent the extracellular matrices of those tissues and act as scaffolds into which cells can migrate and proliferate, thu.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Isoflurane (Isoflo)	Henry Schine Animal Health	17579	gas anesthetic
Optixcare Eye Lubricant	Henry Schine Animal Health	OPX4240	Ocular lubricant
Oster clippers	Henry Schine Animal Health	6092	hair clippers
Betadine surgical scrub	Henry Schine Animal Health	1618	antiseptic iodophor
Sterile scalpel	Henry Schine Animal Health	329	#10 scalpel
9" x 12" disposable surgical drape	Braintree Scientific, Inc.	SP-RPS	Surgical drape
4-0 nylon suture	Braintree Scientific, Inc.	SUT 812	Suture material
4-0 Absorbable Suture	Henry Schine Animal Health	29242	Synthetic absorbable suture
9 mm Autoclips and applier	Braintree Scientific, Inc.	ACS KIT	Surgical staples for closure of skin incision
Torbugesic/analgesic	Henry Schein Animal Health	12084	Butorphanol tartarate for post-operative analgesia
Small intestinal submucosa (SIS)	Cook Biotech, Inc.		Implant material for bridging experimental abdominal wall defect
Rats	Harlan, Inc.	Sprague Dawley	Animal for hernia modeling