Name: use of a rat model to study ventral abdominal hernia repair
Uploaded: 2017-10-02T12:30:00.000+00:00
Duration: 5 min 47 s
Description: Watch this Scientific Journal Video about Use of a Rat Model to Study Ventral Abdominal Hernia Repair at JoVE.com

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 veterinarian or manager can direct the investigator to appropriate sources. Rats of approximately 250 g body weight are suitable for this procedure.</li>
	<li>One day prior to surgery, examine the animals to be used to ensure that they are clinically healthy. In this regard, weigh the animal and assess the body condition; note any abnormality in respiration, the presence of any open wounds or masses, and the general activity level of the animal. Note any abnormality in the surgical record and consider such observations as potential exclusion criteria.</li>
</ol>
2. Anesthesia and Preparation of Animal for Aseptic Surgery
<ol>
	<li>For analgesia, administer 1.1 - 1.2 mg/kg of sustained release buprenorphine, subcutaneously to the rat 2 h&#160;before surgery.&#160;Apply ophthalmic ointment to both eyes, and administer 2 mL of warmed sterile physiologic saline subcutaneously.</li>
	<li>Anesthetize the rat with an intraperitoneal dose of ketamine hydrochloride (90 mg/kg) and xylazine (10 mg/kg). Apply a small amount of ocular lubricant to each eye to prevent corneal dessication. Once the animal&#8217;s respiration is steady and there is no longer any response to a firm toe pinch, the rat has reached a level of anesthesia sufficient for surgery. An acceptable level of anesthesia can be further confirmed by the presence of deep, regular respiration, and normal color of the eye (versus pallor, which might suggest inadequate cardiovascular perfusion).</li>
	<li>Shave the ventral abdomen with a commercial clippers from the pubis to the sternum and from the lateral margins on the ventrum. Remove the clipped hair by applying a moist paper towel to the area.</li>
	<li>Scrub the shaved area with an iodophor antiseptic followed by a wipe with 70% ethanol. Apply surgical drapes so that a window for the incision can be isolated from potential contamination.</li>
	<li>Don a sterile surgical gown, a face mask, and a hair bonnet. Thoroughly wash and scrub hands with soap and don sterile surgical gloves.</li>
</ol>
3. Creation and Repair of the Ventral Abdominal Hernia
<ol>
	<li>Prior to surgery, sterilize surgical instruments by autoclave.</li>
	<li>Using a scalpel, make an approximately 3 - 4 cm vertical incision along the ventral midline down to the level of the abdominal musculature. Lift the abdominal wall gently with a forceps and create a small opening through the linea alba. To protect the underlying viscera, insert a forceps through the hole and into the abdominal cavity to serve as a protective guide as the muscle wall is incised to create an approximately 2 cm x 2 cm full thickness defect, cutting approximately 1 cm lateral from each side of the midline on both ends of the linea alba incision.</li>
	<li>Lay a pre-cut 2 cm x 2 cm section of mechanical bridging material, 4-layer SIS in this case (Figure 1), over the defect. 
	Note: Alternatively, an underlay approach can be used in which the section of material is placed into the abdominal cavity to cover the defect from the interior aspect.</li>
	<li>Suture the four corners of the bridging material to the abdominal wall muscle using 4-0 silk or nylon in a simple interrupted suture pattern. 
	Note: The use of non-absorbable suture allows easy identification of the implanted material upon harvest versus absorbable suture material.</li>
	<li>Secure each edge of the material with three additional sutures spaced equally. Examine the entire circumferential edge to ensure that significant gaps do not exist that might allow passage of viscera through the abdominal wall; and, if such gaps exist, place additional sutures to further secure the margin.</li>
	<li>Close the subcutaneous tissue with 4-0 absorbable suture in a simple interrupted pattern. Close the skin with surgical staples, though suture applied in a simple interrupted pattern may also be used.</li>
	<li>Do not leave the animal unattended until it has regained sufficient consciousness to regain sternal recumbency; and do not return an animal that has undergone surgery to the company of other animals until it has fully recovered from anesthesia. During this time, keep the animal in a warm area to prevent hypothermia.</li>
	<li>Examine animals daily that have undergone this procedure to ensure full recovery and normal healing. Remove skin staples with a staple remover 7 - 10 days following surgery.</li>
</ol>
4. Harvest of the Implanted Material
<ol>
	<li>Consistent with the needs of the study, euthanize, with carbon dioxide overdose administered at a chamber fill rate of 10 to 30%, the animals at a pre-determined time, often 21 - 28 days following surgery.</li>
	<li>Using standard necropsy tools, open the skin and abdominal wall and expose the area of the implant. 
	Note: If non-absorbable sutures were used to secure the implant, the material can be identified by the original sutures (Figure 2).</li>
	<li>Observe any gross pathological observations including any adverse reactions (e.g., wound dehiscence, abscess, seroma, hematoma) and adhesion extent and tenacity to the underlying viscera.</li>
	<li>Remove the implant site by cutting a wide section of tissue that includes the implant. Place the sample in a fixative, such as 10% neutral buffered formalin, in preparation for processing for histological examination and characterization.</li>
</ol>

<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>

One of the authors (CJ) is employed by Cook Biotech, Inc., the manufacturer of medical grade SIS.

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

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Research

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Bioengineering

9.2K Views.  University of Minnesota. 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.

Video: Use of a Rat Model to Study Ventral Abdominal Hernia Repair

Mouse Model of Surgically-induced Endometriosis by Auto-transplantation of Uterine Tissue

Endometriosis is a chronic, painful disease whose etiology remains unknown. Furthermore, treatment of endometriosis can require laparoscopic removal of lesions, and/or chronic pharmaceutical management of pain and infertility symptoms. The cost associated with endometriosis has been estimated at 22 billion dollars per year in the United States1. To further our understanding of mechanisms underlying this enigmatic disease, animal models have been employed. Primates spontaneously develop endometriosis and therefore primate models most closely resemble the disease in women. Rodent models, however, are more cost effective and readily available2. The model that we describe here involves an autologous transfer of uterine tissue to the intestinal mesentery (Figure 1) and was first developed in the rat3 and later transferred to the mouse4. The goal of the autologous rodent model of surgically-induced endometriosis is to mimic the disease in women. We and others have previously shown that the altered gene expression pattern observed in endometriotic lesions from mice or rats mirrors that observed in women with the disease5,6. One advantage of performing the surgery in the mouse is that the abundance of transgenic mouse strains available can aid researchers in determining the role of specific components important in the establishment and growth of endometriosis. An alternative model in which excised human endometrial fragments are introduced to the peritoneum of immunocompromised mice is also widely used but is limited by the lack of a normal immune system which is thought to be important in endometriosis2,7. Importantly, the mouse model of surgically induced endometriosis is a versatile model that has been used to study how the immune system8, hormones9,10 and environmental factors11,12 affect endometriosis as well as the effects of endometriosis on fertility13 and pain14.

A description of the surgical induction of endometriosis in mice and rats by auto-transplantation of uterine tissue to the arterial cascade of the intestinal mesentery.

Endometriosis is a chronic, painful disease whose etiology remains unknown. Furthermore, treatment of endometriosis can require laparoscopic removal of ...

Medicine

The Helsinki Rat Microsurgical Sidewall Aneurysm Model

Experimental saccular aneurysm models are necessary for testing novel surgical and endovascular treatment options and devices before they are introduced into clinical practice. Furthermore, experimental models are needed to elucidate the complex aneurysm biology leading to rupture of saccular aneurysms.
Several different kinds of experimental models for saccular aneurysms have been established in different species. Many of them, however, require special skills, expensive equipment, or special environments, which limits their widespread use. A simple, robust, and inexpensive experimental model is needed as a standardized tool that can be used in a standardized manner in various institutions.
The microsurgical rat abdominal aortic sidewall aneurysm model combines the possibility to study both novel endovascular treatment strategies and the molecular basis of aneurysm biology in a standardized and inexpensive manner. Standardized grafts by means of shape, size, and geometry are harvested from a donor rat&#39;s descending thoracic aorta and then transplanted to a syngenic recipient rat. The aneurysms are sutured end-to-side with continuous or interrupted 9-0 nylon sutures to the infrarenal abdominal aorta.
We present step-by-step procedural instructions, information on necessary equipment, and discuss important anatomical and surgical details for successful microsurgical creation of an abdominal aortic sidewall aneurysm in the rat.

Microsurgical sidewall aneurysms in rats are created by end-to-side anastomosis of an aortic graft to the abdominal aorta. We present step-by-step instructions and discuss anatomical and surgical details for successful experimental saccular aneurysm creation.

Experimental saccular aneurysm models are necessary for testing novel surgical and endovascular treatment options and devices before they are introduced ...

Creation of a Rodent Model of Abdominal Aortic Aneurysm by Blocking Adventitial Vasa Vasorum Perfusion

The adventitial vasa vasorum (VV) provides oxygen and nourishment to the aortic wall. Hypoxia in the aortic wall can cause enlarged abdominal aortic aneurysms (AAAs). This article introduces and describes a standard protocol used to induce AAAs through adventitial VV hypoperfusion created with a combination of polyurethane catheter insertion into the aortic lumen and suture ligation of the infrarenal abdominal aorta.
The protocol involves the use of male rats weighing 300-400 g, which are provided food and water ad libitum. After laparotomy with a ventral midline abdominal incision, exfoliation of the aorta is performed, which blocks blood flow from the perivascular tissue. Aortotomy involving a small incision adjacent to the renal artery branches is performed, and a polyurethane catheter is inserted using an 18-gauge indwelling needle. After repairing the incision, tight ligation of the aorta over the catheter blocks VV blood flow from the proximal direction through the aortic wall without disturbing the aortic blood flow. This technique can induce an AAA with progressive aortic dilatation.
The greatest benefit of this model is that VV hypoperfusion causes tissue hypoxia and the development of an infrarenal AAA, which has morphological and pathological characteristics similar to those of a human AAA.

Polyurethane catheter insertion into the aortic lumen and suture ligation of the aorta induce chronic hypoxia due to hypoperfusion of the adventitial vasa vasorum. This article describes a novel animal model of abdominal aortic aneurysm (AAA) with characteristics similar to those of AAA in humans.

The adventitial vasa vasorum (VV) provides oxygen and nourishment to the aortic wall. Hypoxia in the aortic wall can cause enlarged abdominal aortic ...

Rat Mesentery Exteriorization: A Model for Investigating the Cellular Dynamics Involved in Angiogenesis

Microvacular network growth and remodeling are critical aspects of wound healing, inflammation, diabetic retinopathy, tumor growth and other disease conditions1, 2. Network growth is commonly attributed to angiogenesis, defined as the growth of new vessels from pre-existing vessels. The angiogenic process is also directly linked to arteriogenesis, defined as the capillary acquisition of a perivascular cell coating and vessel enlargement. Needless to say, angiogenesis is complex and involves multiple players at the cellular and molecular level3. Understanding how a microvascular network grows requires identifying the spatial and temporal dynamics along the hierarchy of a network over the time course of angiogenesis. This information is critical for the development of therapies aimed at manipulating vessel growth.
The exteriorization model described in this article represents a simple, reproducible model for stimulating angiogenesis in the rat mesentery. It was adapted from wound-healing models in the rat mesentery4-7, and is an alternative to stimulate angiogenesis in the mesentery via i.p. injections of pro-angiogenic agents8, 9. The exteriorization model is attractive because it requires minimal surgical intervention and produces dramatic, reproducible increases in capillary sprouts, vascular area and vascular density over a relatively short time course in a tissue that allows for the two-dimensional visualization of entire microvascular networks down to single cell level. The stimulated growth reflects natural angiogenic responses in a physiological environment without interference of foreign angiogenic molecules. Using immunohistochemical labeling methods, this model has been proven extremely useful in identifying novel cellular events involved in angiogenesis. Investigators can readily correlate the angiogenic metrics during the time course of remodeling with time specific dynamics, such as cellular phenotypic changes or cellular interactions4, 5, 7, 10, 11.

This article describes a simple model for stimulating angiogenesis in the rat mesentery. The model produces dramatic increases in capillary sprouting, vascular area and vascular density over a relatively short time course in a tissue that allows en face visualization of entire microvascular networks down to the single cell level.

Microvacular network growth and remodeling are critical aspects of wound healing, inflammation, diabetic retinopathy, tumor growth and other disease ...

Biology

A Rat Model of Orthotopic Liver Transplantation Using a Novel Magnetic Anastomosis Technique for Suprahepatic Vena Cava Reconstruction

The rat model of orthotopic liver transplantation (OLT) is essential for transplant research. It is a very sophisticated animal model and requires a steep learning curve. The introduction of the cuff technique for anastomosis of the portal vein (PV) and infrahepatic vena cava (IHVC) has significantly simplified the transplant procedure in rats. However, due to the short anterior wall of the recipients' suprahepatic vena cava (SHVC), the cuff technique is very difficult to use for the reconstruction of the SHVC. Most researchers in this field still use the hand-suture technique for SHVC reconstruction, which makes it the bottleneck step in rat orthotopic liver transplantation. The magnetic anastomosis technique (i.e., magnamosis) is a method of connecting two vessels using the attractive force between two magnets. Our recent study has shown that the magnetic anastomosis technique is superior to the hand-suture technique for SHVC reconstruction in rats. In this article, we show a step-by-step protocol for SHVC reconstruction in rats using the novel magnetic anastomosis technique. In this model, the reconstruction of the PV and IHVC was performed by the standard cuff technique, while the reconstruction of the bile duct (BD) was performed by a stent technique. The hepatic re-arterialization was not performed. The magnetic anastomosis technique made SHVC reconstruction much easier and significantly shortened the anphepatic phase. After a reasonable learning curve, even researchers without advanced microsurgical skills can produce reliable and reproducible results using this rat model of OLT.

The reconstruction of the suprahepatic vena cava (SHVC) remains a difficult step in rat orthotopic liver transplantation. In this article, we show a step-by-step protocol for SHVC reconstruction in rats using a novel magnetic anastomosis technique.

The rat model of orthotopic liver transplantation (OLT) is essential for transplant research. It is a very sophisticated animal model and requires a steep ...

Creation of Colonic Anastomosis in Mice

Intestinal anastomoses are commonly performed in both elective and emergent operations. Even so, anastomotic leaks are a highly feared complications of colonic surgeries and can occur in up to 26% of surgical anastomoses, with mortality being up to 39% for patients with such a leak. Currently, there remains a paucity of data detailing the cellular mechanisms of anastomotic healing. Devising preventative strategies and treatment modalities for anastomotic leak could be greatly potentiated by a better understanding of appropriate anastomotic healing.
A murine model is ideal as previous studies have shown that the murine anastomosis is the most clinically similar to the human case as compared with other animal models. We offer an easily reproducible murine model of colonic anastomosis in mice that will allow for further illustration of anastomotic healing.

Anastomotic leak or breakdown after surgery is a major cause of postoperative morbidity and mortality. Our surgery for creating a colonic anastomosis is a reliable and reproducible method for studying the healing mechanisms of anastomoses.

Intestinal anastomoses are commonly performed in both elective and emergent operations. Even so, anastomotic leaks are a highly feared complications of ...

A Pre-clinical Rat Model for the Study of Ischemia-reperfusion Injury in Reconstructive Microsurgery

Ischemia-reperfusion injury is the main cause of flap failure in reconstructive microsurgery. The rat is the preferred preclinical animal model in many areas of biomedical research due to its cost-effectiveness and its translation to humans. This protocol describes a method to create a preclinical free skin flap model in rats with ischemia-reperfusion injury. The described 3 cm x 6 cm rat free skin flap model is easily obtained after the placement of several vascular ligatures and the section of the vascular pedicle. Then, 8 h after the ischemic insult and completion of the microsurgical anastomosis, the free skin flap develops the tissue damage. These ischemia-reperfusion injury-related damages can be studied in this model, making it a suitable model for evaluating therapeutic agents to address this pathophysiological process. Furthermore, two main monitoring techniques are described in the protocol for the assessment of this animal model: transit-time ultrasound technology and laser speckle contrast analysis.

Here, we describe a pre-clinical animal model for studying the pathophysiology of ischemia-reperfusion injury in reconstructive microsurgery. This free skin flap model based on the superficial caudal epigastric vessels in the rat may also allow for the evaluation of different therapies and compounds to counteract ischemia-reperfusion injury-related damage.

Ischemia-reperfusion injury is the main cause of flap failure in reconstructive microsurgery. The rat is the preferred preclinical animal model in many ...

Development of a Uterosacral Ligament Suspension Rat Model

Pelvic organ prolapse (POP) is a common pelvic floor disorder (PFD) with the potential to significantly impact a woman's quality of life. Approximately 10%-20% of women undergo pelvic floor repair surgery to treat prolapse in the United States. PFD cases result in an overall $26.3 billion annual cost in the United States alone. This multifactorial condition has a negative impact on the quality of life and yet the treatment options have only dwindled in the recent past. One common surgical option is uterosacral ligament suspension (USLS), which is typically performed by affixing the vaginal vault to the uterosacral ligament in the pelvis. This repair has a lower incidence of complications compared to those with mesh augmentation, but is notable for a relatively high failure rate of up to 40%. Considering the lack of standard animal models to study pelvic floor dysfunction, there is an urgent clinical need for innovation in this field with a focus on developing cost-effective and accessible animal models. In this manuscript, we describe a rat model of USLS involving a complete hysterectomy followed by fixation of the remaining vaginal vault to the uterosacral ligament. The goal of this model is to mimic the procedure performed on women to be able to use the model to then investigate reparative strategies that improve the mechanical integrity of the ligament attachment. Importantly, we also describe the development of an in situ tensile testing procedure to characterize interface integrity at chosen time points following surgical intervention. Overall, this model will be a useful tool for future studies that investigate treatment options for POP repair via USLS.

Pelvic organ prolapse affects millions of women worldwide and yet some common surgical interventions have failure rates as high as 40%. The lack of standard animal models to investigate this condition impedes progress. We propose the following protocol as a model for uterosacral ligament suspension and in vivo tensile testing.

Pelvic organ prolapse (POP) is a common pelvic floor disorder (PFD) with the potential to significantly impact a woman's quality of life. Approximately ...

Urethral Stricture Induction Followed by Buccal Mucosa Graft Urethroplasty in a Rat Model

Urethral reconstruction is an important area of expertise for urologists. The buccal mucosa is considered the best option when urethral grafting is necessary, although in some cases, it is inappropriate or needs to be optimized to repair a given stricture. Therefore, developing innovative procedures and evaluating their putative success in experimental models is crucial to fit the clinical need. With this goal, this study describes a protocol in which urethral stricture was induced by electrocautery in Wistar rats. Urethral reconstruction was performed 1 week later with a buccal mucosa graft, harvested from the lower lip, and placed in a ventral onlay fashion. A retrograde urethrogram showed a significant improvement in urethral diameter after urethroplasty compared to the respective value after stricture induction. Additionally, the graft placement was assessed by blood perfusion analysis using laser Doppler. As expected, a dark blue area corresponded to the non-vascularized buccal mucosa graft. This procedure can successfully simulate the normal pathophysiological process of urethral injury and tissue modulation, as well as urethral reconstruction using a buccal mucosa graft in a reproducible manner, and serve as the basis for future research based on tissue engineering or urethral grafts.

In the present protocol, a urethral stricture induction was developed in Wistar rats, followed by urethral reconstruction with a buccal mucosa graft. A retrograde urethrogram and laser Doppler assessment were performed, validating urethral reconstruction (after stricture formation) and graft placement.

Urethral reconstruction is an important area of expertise for urologists. The buccal mucosa is considered the best option when urethral grafting is ...

Experimental Rat Model of Pouchitis for Studying Ulcerative Colitis Pathogenesis and Treatment

A Rat Model of Pouchitis Following Proctocolectomy and Ileal Pouch-Anal Anastomosis Using Dextran Sulfate Sodium

Ulcerative colitis (UC) is a chronic immune-mediated disease that affects the entire colon and rectum with a relapsing and remitting course, causing lifelong morbidity. When medical treatment is ineffective, especially in cases of massive gastrointestinal bleeding, perforation, toxic megacolon, or carcinogenesis, surgery becomes the last line of defense to cure UC. Total colorectal resection and ileal pouch-anal anastomosis (IPAA) offer the best chance for long-term treatment. Pouchitis is the most common and troublesome postoperative complication. In this investigation, microsurgery is employed to create an ileal pouch model in experimental rats via IPAA surgery. Subsequently, a sustained rat model of pouchitis is established by inducing inflammation of the ileal pouch with dextran sulfate sodium (DSS). The successful establishment of rat pouchitis is validated through analysis of postoperative general status, weight, food and water intake, fecal data, as well as pouch tissue pathology, immunohistochemistry, and inflammatory factor analysis. This experimental animal model of pouchitis provides a foundation for studying the pathogenesis and treatment of the condition.

Author Spotlight: Developing a Rat Model for Pouchitis Research and Treatment

This protocol describes the method for establishing a rat model of pouchitis. The ileal pouch model was created by performing ileal pouch-anal anastomosis (IPAA) surgery using microsurgical techniques. After the surgery, the rat was treated with 4% dextran sulfate sodium (DSS) for 4 days.

Ulcerative colitis (UC) is a chronic immune-mediated disease that affects the entire colon and rectum with a relapsing and remitting course, causing ...