The authors wish to thank Valerie Schroeder for her assistance with technical aspects of this work. Work related to development of this model was supported by Cook Biotech, Inc. (West Lafayette, IN USA).

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
<ol>
	<li>Acquire pathogen-free Sprague Dawley rats from a reputable vendor or breeding colony. 
	Note: Often, the facility veterinari...

<ol>
	<li>Poussier, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+review+of+available+prosthetic+material+for+abdominal+wall+repair.">A review of available prosthetic material for abdominal wall repair.</a> J. Visc. Surg. 150 (1), 52-59 (2013).</li><li>Hjort, H., Mathisen, T., Alves, A., Clermont, G., Boutrand, J. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Three-year+results+from+a+preclinical+implantation+study+of+a+long-term+resorbable+surgical+mesh+with+time-dependent+mechanical+characteristics.">Three-year results from a preclinical implantation study of a long-term resorbable surgical mesh with time-dependent mechanical characteristics.</a> Hernia. 16 (2), 191-197 (2012).</li><li>Ko, R., Kazacos, E. A., Snyder, S., Ernst, D. M. J., Lantz, G. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tensile+strength+comparison+of+small+intestinal+submucosa+body+wall+repair.">Tensile strength comparison of small intestinal submucosa body wall repair.</a> J. Surg. Res. 135 (1), 9-17 (2006).</li><li>Garcia-Moreno, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparing+the+host+tissue+response+and+peritoneal+behavior+of+composite+meshes+used+for+ventral+hernia+repair.">Comparing the host tissue response and peritoneal behavior of composite meshes used for ventral hernia repair.</a> J. Surg. Res. 193 (1), 470-482 (2015).</li><li>Soiderer, E. E., Lantz, G. C., Kazacos, E. A., Hodde, J. P., Wiegand, R. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Morphologic+study+of+three+collagen+materials+for+body+wall+repair.">Morphologic study of three collagen materials for body wall repair.</a> J. Surg. Res. 118 (2), 161-175 (2004).</li><li>Liu, Z., Tang, R., Zhou, Z., Song, Z., Wang, H., Gu, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+two+porcine-derived+materials+for+repairing+abdominal+wall+defect+in+rats.">Comparison of two porcine-derived materials for repairing abdominal wall defect in rats.</a> PLOS One. 6 (5), e20520 (2011).</li><li>Zhang, J., Wang, G. Y., Xiao, Y. P., Fan, L. Y., Wang, Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+biomechanical+behavior+and+host+response+to+porcine-derived+small+intestine+submucosa,+pericardium+and+dermal+matrix+acellular+grafts+in+a+rat+abdominal+defect+model.">The biomechanical behavior and host response to porcine-derived small intestine submucosa, pericardium and dermal matrix acellular grafts in a rat abdominal defect model.</a> Biomaterials. 32 (29), 7086-7095 (2011).</li><li>Ma, J., Sahoo, S., Baker, A. R., Derwin, K. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Investigating+muscle+regeneration+with+a+dermis/small+intestinal+submucosa+scaffold+in+a+rat+full-thickness+abdominal+wall+defect+model.">Investigating muscle regeneration with a dermis/small intestinal submucosa scaffold in a rat full-thickness abdominal wall defect model.</a> J.Biomed.Mater.Res.Part B. 103 (2), 355-364 (2015).</li><li>Greca, F. H., Souza-Filho, Z. A., Giovanni, A., Rubin, M. R., Kuenzer, R. F., Reese, F. B., Araujo, L. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+influence+of+porosity+on+the+integration+histology+of+two+polypropylene+meshes+for+the+treatment+of+abdominal+wall+defects+in+dogs.">The influence of porosity on the integration histology of two polypropylene meshes for the treatment of abdominal wall defects in dogs.</a> Hernia. 12 (1), 45-49 (2008).</li><li>Hiles, M., Record-Ritchie, R. D., Altizer, A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Are+biologic+grafts+effective+for+hernia+repair?+A+systematic+review+of+the+literature.">Are biologic grafts effective for hernia repair? A systematic review of the literature.</a> Surg. Innov. 16 (1), 26-37 (2009).</li><li>Helton, W. S., Fisichella, P. M., Berger, R., Horgan, S., Espat, N. J., Abcarian, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Short-term+outcomes+with+small+intestinal+submucosa+for+ventral+abdominal+hernia.">Short-term outcomes with small intestinal submucosa for ventral abdominal hernia.</a> Arch. Surg. 140 (6), 560-562 (2005).</li><li>Franklin, M. E., Trevino, J. M., Portillo, G., Vela, I., Glass, J. L., Gonzalez, J. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+use+of+porcine+small+intestinal+submucosa+as+a+prosthetic+material+for+laparascopic+hernia+repair+in+infected+and+potentially+contaminated+fields:+long-term+follow-up.">The use of porcine small intestinal submucosa as a prosthetic material for laparascopic hernia repair in infected and potentially contaminated fields: long-term follow-up.</a> Surg. Endosc. 22 (9), 1941-1946 (2008).</li><li>Clarke, K. M., Lantz, G. C., Salisbury, S. K., Badylak, S. F., Hiles, M. C., Voytik, S. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intestine+submucosa+and+polypropylene+mesh+for+abdominal+wall+repair+in+dogs.">Intestine submucosa and polypropylene mesh for abdominal wall repair in dogs.</a> J. Surg. Res. 60 (1), 107-114 (1996).</li><li>Sarikava, A., Record, R., Wu, C. C., Tullius, B., Badylak, S. F., Ladisch, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Antimicrobial+activity+associated+with+extracellular+matrices.">Antimicrobial activity associated with extracellular matrices.</a> Tissue Eng. 8 (1), 63-71 (2002).</li><li>Serra, R., Grande, R., Butrico, L., Rossi, A., Settimio, U. F., Caroleo, B., Amato, B., Gallelli, L., de Franciscis, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chronic+wound+infections:+the+role+of+Pseudomonas+aeruginosa+and+Staphylococcus+aureus.">Chronic wound infections: the role of Pseudomonas aeruginosa and Staphylococcus aureus.</a> Expert Rev. Anti. Infect. Ther. 13 (5), 605-613 (2015).</li></ol>

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...

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 synthetic materials are typically non-absorbable and include polypropylene, polyethylene terephthalate polyester, and expanded polytetrafluoroethylene, while other synthetic implants combine one of the non-absorbable materials with an absorbable polymer such as polygalactine.1 In contrast, natural material implants are generally derived from either animal or human cadaveric sources. Natural materials used for hernia repair are typically rich in collagen and act as a scaffold for ingrowth and integration of host tissue.
The desire to develop and optimize new materials for ventral abdominal hernia repair requires an appropriate animal model for evaluation of candidate materials. Studies have been conducted in a variety of species, including sheep,2 pigs,3 rabbits,4 rats,5,6,7,8 and dogs.9&#160; The advantage of using rats for such studies is that they offer an easily handled model available in a variety of inbred strains to allow for control of genetic variability. In addition, the smaller overall body surface area of the rat compared to the other species listed above permit evaluation of materials that may be experimental in nature and, therefore, not abundant.&#160; Further, reduced costs associated with rats versus other species allow for relatively increased ability to screen candidate materials for use in repair of ventral abdominal hernia.&#160; Considerations for materials typically include ease of handling by the surgeon, strength, ability to incorporate into host tissue, biocompatibility, and resistance to infection.
As an example, porcine small intestinal submucosa (SIS) is a natural biomaterial that has been used for a wide variety of tissue repair indications, including repair of ventral abdominal, inguinal, and diaphragmatic hernias.10,11,12 SIS is rapidly incorporated into host tissue and has been found to be generally resistant to infection and so the material has particular utility in contaminated fields.13,14&#160; In the rat model, SIS has demonstrated ease of handling, good tensile strength as determined by the&#160; uniaxial tensile failure test, and promotion of tissue ingrowth in terms of collagen deposition and neovascularization.6,7
Accurate surgical bridging of the defect is an essential feature of productive modeling when evaluating candidate repair materials. The animal must be sufficiently anesthetized and aseptic technique strictly followed. Further, an abdominal wall defect of standard size must be carefully created and then bridged in a manner that sufficiently secures the material to the margins of the defect.8 This protocol provides a standard method to be followed for surgical creation, and repair of, a ventral abdominal hernia using SIS as an example bridging material in a rat.

<table border="0" cellpadding="0" cellspacing="0" width="573">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="84">
			<td height="84" style="height:84px;width:216px;">Isoflurane (Isoflo)</td>
			<td style="width:71px;">Henry Schine Animal Health</td>
			<td align="right" style="width:119px;">17579</td>
			<td style="width:167px;">gas anesthetic</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:216px;">Optixcare Eye Lubricant</td>
			<td style="width:71px;">Henry Schine Animal Health</td>
			<td style="width:119px;">OPX4240</td>
			<td>Ocular lubricant</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:216px;">Oster clippers</td>
			<td style="width:71px;">Henry Schine Animal Health</td>
			<td align="right" style="width:119px;">6092</td>
			<td>hair clippers</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:216px;">Betadine surgical scrub</td>
			<td style="width:71px;">Henry Schine Animal Health</td>
			<td align="right" style="width:119px;">1618</td>
			<td>antiseptic iodophor</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:216px;">Sterile scalpel</td>
			<td style="width:71px;">Henry Schine Animal Health</td>
			<td align="right" style="width:119px;">329</td>
			<td>#10 scalpel</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">9&#34; x 12&#34; disposable surgical drape</td>
			<td style="width:71px;">Braintree Scientific, Inc.</td>
			<td style="width:119px;">SP-RPS</td>
			<td>Surgical drape</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">4-0 nylon suture</td>
			<td style="width:71px;">Braintree Scientific, Inc.</td>
			<td style="width:119px;">SUT 812</td>
			<td>Suture material</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:216px;">4-0 Absorbable Suture</td>
			<td style="width:71px;">Henry Schine Animal Health</td>
			<td align="right" style="width:119px;">29242</td>
			<td>Synthetic absorbable suture</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">9 mm Autoclips and applier</td>
			<td style="width:71px;">Braintree Scientific, Inc.</td>
			<td style="width:119px;">ACS KIT</td>
			<td>Surgical staples for closure of skin incision</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:216px;">Torbugesic/analgesic</td>
			<td style="width:71px;">Henry Schine Animal Health</td>
			<td align="right" style="width:119px;">12084</td>
			<td>Butorphanol tartarate for post-operative analgesia</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Small intestinal submucosa (SIS)</td>
			<td style="width:71px;">Cook Biotech, Inc.</td>
			<td style="width:119px;"></td>
			<td>Implant material for bridging experimental abdominal wall defect</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Rats</td>
			<td style="width:71px;">Harlan, Inc.</td>
			<td style="width:119px;">Sprague Dawley</td>
			<td>Animal for hernia modeling</td>
		</tr>
	</tbody>
</table>

use of a rat model to study ventral abdominal hernia repair

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.

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 ...

Watch this Scientific Journal Video about Use of a Rat Model to Study Ventral Abdominal Hernia Repair at JoVE.com

Use of a Rat Model to Study Ventral Abdominal Hernia Repair

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.

Ventral abdominal hernia is a relatively common clinical condition that sometimes requires herniorraphy (surgical repair). The repair of ventral abdominal ...

The overall goal of this ventral abdominal hernia repair model is to facilitate the assessment of potential hernia repair biomaterials. This method can help answer key questions in the surgical biomaterials field about the suitability and biocompatibility of candidate materials for ventral abdominal hernia repair. The main advantage of this technique is that it utilizes a rat model, thereby allowing the evaluation of hernia repair materials that may be of limited supply.After confirming the appropriate level of anesthesia of a healthy 250 gram adult rat by toe pinch, apply lubricant to the animal's eyes and subcutaneously administer sterile saline. Use a pair of clippers to shave the ventral abdomen from the pubis to the sternum and from the lateral margins on the ventrum. Apply a moist paper towel to the shaved area to remove the clipped hair, and scrub the exposed skin with an iodoform antiseptic and a 70%ethanol wipe.After donning the appropriate personal protective equipment, thoroughly scrub both hands with soap and don a pair of sterile surgical gloves. Next, drape the animal. And use a scalpel to make an approximately three to four centimeter vertical incision down the ventral midline to abdominal musculature.Using forceps, gently lift the abdominal wall and create a small opening through the linea alba. Then, to protect the underlying viscera, insert another forceps through the hole into the abdominal cavity to create an approximately two by two centimeter full thickness defect, cutting approximately one centimeter lateral from each side of the midline on both ends of the linea alba incision. Next, lay a precut two by two centimeter section of implant material over the defect.Because the abdominal wall will retract laterally upon incision, it is important to establish the general anatomical boundaries, ensuring the creation of a defect in the tissue wall that corresponds to the size of the implant. And use a 4-0 nylon suture to suture the four corners of the bridging material to the abdominal wall in a simple interrupted suture pattern. Secure each edge of the material with three additional equally spaced sutures.Then examine the entire circumferential edge to ensure significant gaps do not exist. Any unsecured implant margins present an opening through which the abdominal viscera can potentially herniate. Therefore it is essential to make sure that all of the edges are anchored to the body wall.When the implant is secure, close the skin with surgical staples. Seven to 10 days after the surgery, remove the skin staples. 21 to 28 days after the surgery, the rat is euthanized.Open the skin and abdominal wall to expose the area of the implant. Note any gross pathological observations, including any adverse reactions and adhesion extent and tenacity to the underlying viscera. Then harvest a wide section of tissue that includes the implant and place the implant site sample into the appropriate fixative for the desired downstream processing procedure if the sample is to be used for histopathological examination.By 28 days after implantation, the small intestinal submucosa or SIS typically demonstrates a good incorporation into the host tissue. In most cases, residual SIS is apparent, although the tissue must often be explored to identify the implanted material. Histological analysis further confirms the gross pathological observations, illustrating a good tissue incorporation with primarily fibrovascular tissue and very little notable residual SIS in demonstrating the utility of the rat ventral abdominal hernia model.Once mastered, this technique can be completed in 30 minutes if it is performed properly. While attempting this procedure, it's important to remember to provide adequate postoperative analgesia to the animal. Following euthanasia and harvest of the implant, other methods like mechanical strength testing can be performed to answer additional questions like, is the reparative abdominal defect sufficiently strong?After watching this video, you should have a good understanding of how to surgically create a ventral abdominal hernia in the rat.

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9.1K visualizações.  University of Minnesota. The overall goal of this ventral abdominal hernia repair model is to facilitate the assessment of potential hernia repair biomaterials. This method can help answer key questions in the surgical biomaterials field about the suitability and biocompatibility of candidate materials for ventral abdominal hernia repair. The main advantage of this technique is that it utilizes a rat model, thereby allowing the evaluation of hernia repair materials that may be of limited supply.After confirmin...