The authors would like to thank Christine Guesdon (Abbott) for the gifts of the Stentgrafts.

Methods
The protocol has been approved by the Bichat-Debr&eacute; Ethic committee (N&deg; 2012-15/698-0074).
The elastase perfusion model has been first described by Anidjar in 19901: abdominal aortic aneurysm is induced by elastase perfusion in male Wistar rats, aged 8 to 9 weeks, 250-300 g. Two to 4 weeks later, a re-laparotomy is performed, and a 3 mm diameter covered coronary stentgraft is used to exclude the aneurysm. The graft, inserted through a distal aortotomy, is deployed under magnified vision. Two weeks later, stentgraft patency is confirmed with an aortography by the left common carotid artery before sacrifice. The whole stented aorta and surrounding tissues are then harvested and conditioned for analysis.
Protocol
1. Step 1 : Abdominal Aortic Aneurysm Induction (Day 0)
<ol>
 <li>Anesthetize the animal with isoflurane, and perform an intra peritoneal penthobarbital injection. 0.1 ml/100 g of penthobarbitol is diluted in 0.1 ml of saline/100 g of animal weight. Anesthesia is adequate for the procedure.</li>
 <li>Shave the abdomen, and clean the skin with alcohol. </li>
 <li>Make Xypho pubic skin incision with a blade. Abdominal muscles layer then peritoneum, avoiding internal organs, are open with scissors. Place the spreaders and wrap the intestines in a wet compress on the left side of the animal.</li>
 <li>Open the posterior peritoneum directly above the aorta, without tearing it. The goal is to prevent future bowel adhesions by economic dissection. </li>
 <li>Ligate all collaterals from the left renal vein to the iliac bifurcation with only one ligature, at the origin of the aorta. If the aorta is stuck to the bowels or the vena cava, there's a high risk of bleeding during the second intervention; this is often fatal for the rat. </li>
 <li>Pass a 4-0 silk twice around the aorta, 15 mm below the left renal vein. It's important to entirely dissect the aorta, approx. 15 mm below the left renal vein and just proximal to the iliac bifurcation to allow insertion of the Gilbert approximator clamps. </li>
 <li>After clamping the aorta proximally just below the left renal vein, and distally just above the iliac bifurcation, remove the adventitia, and perform a small aortotomy as proximal as possible to the distal clamp. The aorta has to be carefully flushed with saline and an angulated canula and all remaining blood washed to avoid clot embolization when declamping.</li>
 <li>Introduce heat-tapered polyethylene tubing (PE 10) smoothly inside the aorta, and pass the 4-0 silk around the aorta (at step 1.6) and tie up to secure the tube and avoid pressure expulsion. </li>
 <li>Inject elastase into a 10 to 13 mm length of aorta (from the proximal clamp to the silk). </li>
 <li>Infuse 725 &mu;l of the elastase solution is d at constant speed-rate in 30 min. It is important to carefully survey the injection: during infusion, the aorta should expand by 140-150% of its normal diameter. </li>
 <li>At the end of the infusion, remove the catheter, flush the elastase with saline, cut the silk and close the aortotomy with about 3 stitches of 10-0 Prolene. Remove the clamps: distal then proximal. Care has to be taken to avoid trans-aortic suture. With a few practice and considering the small length of the aortotomy, aorta thrombosis is extremely rare. </li>
 <li>Close abdominal wall with a continuous absorbable suture, and the skin with interrupted non absorbable sutures. Inject a 5 mg/kg dose of Carprofen subcutaneously to prevent pain. Return the rats to their cage and give the standard rat laboratory chow and water ad libidum. </li>
</ol>
2. Step 2 : Abdominal Aortic Aneurysm Exclusion with a Coronary PTFE (Polytetrafluoroethylene) Covered Stentgraft (Day 15-30)
<ol>
 <li>Prior to the operation, dilute Aspirin 1,000 mg in 1 L of water. Daily water intake was estimated of 10-12 ml/100 g/ of body weight a day. </li>
 <li>After anesthesia as previously described, perform a re-laparotomy, carefully avoiding potential internal organs adherent to the abdominal wall. Aneurysm was defined by an increase of 50% at least of the aorta compared to proximal aorta diameter measured under direct vision. Based on our experience, the success rate is 90%, including early deaths, mostly due to aorta burst (unpublished data) </li>
 <li>Dissect the aorta at the aortic bifurcation and also at the proximal neck. The aneurysm should arise a few millimeters below the left renal vein; this allows a satisfactory length between the distal neck and the distal clamp to insert the catheter, and suture the aorta. 
 Stentgraft length depends on the aneurysm size. Both proximal and distal necks should be covered by at least 2 millimeters. </li>
 <li>Wrap a double loop silk around the proximal neck. Clamp the proximal aorta above the aneurysm and below the left renal artery, and distally above the aortic bifurcation. </li>
 <li>Perform a large aortotomy just above the previous aortotomy to avoid tearing the aortic wall when introducing the stentgraft. Do not rinse the aorta to preserve integrity of the thrombus. Push the stentgraft towards the proximal clamp. Remove the clamp is and control the tension of the silk to allow graft progression. Adapt the tension around the delivering catheter to allow stentgraft progression until the proximal edge of the stentgraft reaches the proximal neck, but also this will prevent massive hemorrhage after proximal clamp removal. The balloon and the proximal end of the delivering catheter may cover the renal arteries, but not the stentgraft which has to be deployed below the renal arteries. </li>
 <li>Deploy the stentgraft under direct visual control using an inflator syringe at 8 atm pressure. Deflate the balloon whilst tightening the silk and remove the balloon shaft. </li>
 <li>Wash the stentgraft with saline. Place a clamp just below the distal part of the aneurysm, and close aorta with interrupted 10-0 Prolene sutures. </li>
 <li>Close the wound, inject Carprofen subcutaneously and let the animals return to their cage. Give the standard laboratory chow and water ad libidum. </li>
</ol>
3. Step 3 : Control of Stentgraft Patency (Day 30)
15 days after stentgraft insertion, perform an arteriography to control graft patency 
<ol>
 <li>After anesthesia, perform a transverse elbow to elbow incision. The left common carotid artery is located beneath the submandibular and sublingual glands and beneath the sternomastoid muscle. 2 cm length exposure is recommended. </li>
 <li>Ligate the artery distally with a silk 4-0. After proximal clamping, insert an 18G catheter retrogradely and secure with a silk 4-0 passed twice around the carotid artery and tied. A sufficient length allows insertion and securing the catheter before proximal clamp is removed. If it's hard to expose 2cm of artery, the tube, clamped after filled with saline can be pushed proximally whilst removing the proximal clamp.</li>
 <li>Inject contrast through the catheter under direct fluoroscopy. Perform a stentgraft angiographic control to both confirm the absence of endoleak which could result of an inappropriate deployment of the stentgraft, and confirm stentgraft patency. This step is important because the high numbers of collaterals vessels allow adequate leg perfusion even with a thrombosed stentgraft. We didn't try to perform Duplex ultrasonography: we postulate that stentgraft steel structure prevents correct assessment of stentgraft patency and endoleaks. </li>
 <li>Sacrifice the rat by exsanguination according to the recommendations18, and the aneurysm, stentgraft, thrombus and aortic wall are harvested for histological or biochemical studies. </li>
</ol>

<ol>
	<li>Anidjar, S., 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=Elastase-induced+experimental+aneurysms+in+rats.">Elastase-induced experimental aneurysms in rats.</a> Circulation. 82, 973-981 (1990).</li><li>Azuma, J., Asagami, T., Dalman, R., Tsao, P. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Creation+of+murine+experimental+abdominal+aortic+aneurysms+with+elastase.">Creation of murine experimental abdominal aortic aneurysms with elastase.</a> J. Vis. Exp. (29), e1280 (2009).</li><li>Parodi, J. C., Palmaz, J. C., Barone, H. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transfemoral+intraluminal+graft+implantation+for+abdominal+aortic+aneurysms.">Transfemoral intraluminal graft implantation for abdominal aortic aneurysms.</a> Ann. Vasc. Surg. 5, 491-499 (1991).</li><li>Lees, T., Stansby, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> The nationalvascular database report, 2009. , (2012).</li><li>Sakalihasan, N., Limet, R., Defawe, O. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Abdominal+aortic+aneurysm.">Abdominal aortic aneurysm.</a> Lancet. 365, 1577-1589 (2005).</li><li>Busuttil, R. W., Abou-Zamzam, A. M., Machleder, H. 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I have nothing to disclose.

Two models of AAA have been already described in our lab: xenograft19 and elastase induced models.1 Elastase model is the most similar to human aortic aneurysms: a large circumferential intraluminal thrombus is then excluded by endovascular aneurysm repair. 
Endoleaks are a usual complication of EVAR14,15. Lots of questions remain unsolved: AAA rupture have been described with low endoleaks, and sometimes without aneurysm sac enlargement16. Endoleak ...

Endovascular skills have progressed since the first endovascular aortic aneurysm repair (EVAR) by Parodi in 19913, almost half of all abdominal aneurysms are now treated by EVAR4. Unlike surgery, EVAR leaves the thrombus, excluding it from systemic bloodstream. Aneurysms are characterized by a hemoglobin rich multi layered thrombus, a thin media, and a fibrosed and inflamed adventitia. The crucial role of proteolysis5 in aneurysm progression has been demonstrated thirty years ago6, 7: aneurysm sac thrombus is associated with a thin aortic wall, lysis of elastin, low density of smooth muscle cells in the media, and a high level of immuno-inflammatory adventitial reaction8,9. These changes suggest that proteolytic enzymatic activity occurs within the thrombus, rather than directly in the aortic wall.
In addition, the luminal layer of the thrombus is rich in agglutinated red blood cells releasing hemoglobin. They are primarily involved in fibrin formation, platelet activation and induce thrombin formation. Finally, thrombus also induces t-PA and plasminogen retention, which are involved in fibrinolysis and recruiting leukocytes, mainly neutrophils. These are 12 times more important in the thrombus than in the blood stream10. Their presence is associated with a high rate of matrix metalloproteinase type 8 (MMP-8), MMP-9 and elastase: they release granular serine proteases and pro oxidative agents leading to degradation of the fibrillar matrix, and ultimately aortic wall rupture9,11-13. 
Elective aneurysm intervention aims to prevent rupture. EVAR leaves both aneurysm wall and thrombus intact. Thus, aneurysm perfusion by aortic collaterals (lumbar arteries, inferior mesenteric artery&#x2026;), is named endoleak, and is a specific complication of endovascular treatment14,15, sometimes leading to rupture even with low pressure endoleaks. Moreover, in certain patients, there is no increase in aneurysm diameter16. Interaction between circulating blood and aneurysmal wall maintains the mentioned intra luminal thrombus biological activity. Hence, Type V endoleaks, defined as expansion of the aneurysm sac without identified endoleak, could be explained by enzymatic activity inside the aneurysm thrombus.
Neither radiological imaging (18FDG-PET scan, platelet activation scintigraphy, iron oxyde contrast MRI17) nor peripheral blood sampling (MMP-9, platelet derived microparticles, plasmin/anti-plasmin complex) used to explore the endovascular impact on aortic aneurysms in humans directly evaluate biochemical pathways.
In our knowledge, there is no any reproducible and cheap experimental aneurysm exclusion animal models. This one allows pre and post aneurysm exclusion biological and histological modifications to be explored.

<table border="1">
<tbody>
 <tr>
 <td></td>
 <td></td>
 <td></td>
 <td>Animals </td>
 </tr>
 <tr>
 <td>Wistar rats</td>
 <td></td>
 <td></td>
 <td>aged from 8 to 9 weeks. Weight range from 350 to 400 g</td>
 </tr>
 <tr>
 <td></td>
 <td></td>
 <td></td>
 <td>Instruments</td>
 </tr>
 <tr>
 <td>Isoflurane anesthesic system</td>
 <td></td>
 <td></td>
 <td>4,5% at the beginning, then 2%</td>
 </tr>
 <tr>
 <td>Penthobarbital</td>
 <td>Ceva sante animale, Libourne, France</td>
 <td></td>
 <td></td>
 </tr>
 <tr>
 <td>Dissection stereomicroscope</td>
 <td></td>
 <td></td>
 <td></td>
 </tr>
 <tr>
 <td>Steriles gloves</td>
 <td></td>
 <td></td>
 <td></td>
 </tr>
 <tr>
 <td>Microsurgical Steriles instruments</td>
 <td>Moria, Antony, France</td>
 <td></td>
 <td>Needle holder,	Forceps, Scissors,Gilbert approximator
o	3 Micro clamps</td>
 </tr>
 <tr>
 <td>N&deg;40 Silk string</td>
 <td></td>
 <td></td>
 <td></td>
 </tr>
 <tr>
 <td>Prolen 9-0 and 10-0</td>
 <td>Ethicon, Johnson &amp; Johnson, Auneau, France</td>
 <td></td>
 <td></td>
 </tr>
 <tr>
 <td>Heat-tapered polyethylene tubing</td>
 <td>PE 10</td>
 <td></td>
 <td></td>
 </tr>
 <tr>
 <td>Syringe infusion pump</td>
 <td></td>
 <td></td>
 <td></td>
 </tr>
 <tr>
 <td>Porcine pancreatic elastase</td>
 <td>Sigma, St. Louis, Mo., USA</td>
 <td></td>
 <td>550 &mu;l of salin is mixed with 175 &mu;l of elastase</td>
 </tr>
 <tr>
 <td>Indeflator</td>
 <td></td>
 <td></td>
 <td></td>
 </tr>
 <tr>
 <td>9 to 16 mm length, 3 mm diameter coronary PTFE covered stentgraft</td>
 <td>Abbott, Abbott Park, Illinois, USA</td>
 <td></td>
 <td></td>
 </tr>
 <tr>
 <td>C-Arm OEC 9800</td>
 <td>GE Medical Systems, Milwaukee, WI</td>
 <td></td>
 <td></td>
 </tr>
 <tr>
 <td>Aspegic 1000 mg</td>
 <td>Aspirin, Sanofi-Aventis, Paris, France</td>
 <td></td>
 <td></td>
 </tr>
 <tr>
 <td></td>
 <td></td>
 <td></td>
 <td>Reagent</td>
 </tr>
 <tr>
 <td>Aerane isoflurane 100ML</td>
 <td>Baxter</td>
 <td>Aerane</td>
 <td></td>
 </tr>
 <tr>
 <td>Penthobarbital</td>
 <td>Centravet</td>
 <td>053pen203</td>
 <td></td>
 </tr>
 <tr>
 <td>Silk Suture 4-0</td>
 <td>Fine Science</td>
 <td>18020-40</td>
 <td></td>
 </tr>
 <tr>
 <td>Microsurgical steriles instruments</td>
 <td>Moria</td>
 <td>9980-9983-9987-204/A-204/D-8148-4877A-4878A</td>
 <td></td>
 </tr>
 <tr>
 <td>Prolen 9-0 and 10-0</td>
 <td>Ethicon</td>
 <td>W2829 &ndash; NS2850</td>
 <td></td>
 </tr>
 <tr>
 <td>Heat tapered Polyethylene tubing : PE 10</td>
 <td>Bioseb</td>
 <td>MRE-010</td>
 <td></td>
 </tr>
 <tr>
 <td>Infusion pump</td>
 <td>World precision instrument</td>
 <td>AL-1000</td>
 <td></td>
 </tr>
 <tr>
 <td>Porcine pancreatic elastase</td>
 <td>Sigma</td>
 <td>E1250-100MG</td>
 <td></td>
 </tr>
 <tr>
 <td>Indeflator</td>
 <td>Longreal</td>
 <td>KY025 25 100</td>
 <td></td>
 </tr>
 <tr>
 <td>Aspegic 1000mg (Aspirin)</td>
 <td>Sanofi-Aventis</td>
 <td>3400931898191</td>
 <td></td>
 </tr>
 <tr>
 <td>C-Arm OEC 9800</td>
 <td>General electric.</td>
 <td>OEC 9800</td>
 <td></td>
 </tr>
 <tr>
 <td>Stentgraft : Jostent</td>
 <td>Abbott</td>
 <td>210CG1230 
 210CG1630</td>
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a new murine model of endovascular aortic aneurysm repair

Endovascular aneurysm exclusion is a validated technique to prevent aneurysm rupture. Long-term results highlight technique limitations and new aspects of Abdominal aortic aneurysm (AAA) pathophysiology. There is no abdominal aortic aneurysm endograft exclusion model cheap and reproducible, which would allow deep investigations of AAA before and after treatment. We hereby describe how to induce, and then to exclude with a covered coronary stentgraft an abdominal aortic aneurysm in a rat. The well known elastase induced AAA model was first reported in 19901 in a rat, then described in mice2. Elastin degradation leads to dilation of the aorta with inflammatory infiltration of the abdominal wall and intra luminal thrombus, matching with human AAA. Endovascular exclusion with small covered stentgraft is then performed, excluding any interactions between circulating blood and the aneurysm thrombus. Appropriate exclusion and stentgraft patency is confirmed before euthanasia by an angiography thought the left carotid artery. Partial control of elastase diffusion makes aneurysm shape different for each animal. It is difficult to create an aneurysm, which will allow an appropriate length of aorta below the aneurysm for an easy stentgraft introduction, and with adequate proximal and distal neck to prevent endoleaks. Lots of failure can result to stentgraft introduction which sometimes lead to aorta tear with pain and troubles to stitch it, and endothelial damage with post op aorta thrombosis. Giving aspirin to rats before stentgraft implantation decreases failure rate without major hemorrhage. Clamping time activates neutrophils, endothelium and platelets, and may interfere with biological analysis.

Aneurysm is fixed in a paraformaldehyde 4% solution during 24 hr, then into a phosphate buffered saline solution until fixation in a resin bloc. We use a HPS (Hematoxylin Phloxin Safran) (Figure 1) staining, showing healing proliferative cells around the PTFE (Figure 2). Mesenchymal cells are then characterized by &alpha;-actin staining (Figure 3).
<img src="/files/ftp_upload/50740/50740fig1.jpg" alt="Figu...

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A New Murine Model of Endovascular Aortic Aneurysm Repair

Histological and biochemical modifications after aneurysm endograft exclusion are still unclear. We describe a new model of endograft implantation on a murine aneurysm. Through thrombus analysis with and without persistant circulating blood stream interface, and new endovascular biomaterials evaluation, this model will help to better understand endovascular aneurysm exclusion pathobiology.

Endovascular aneurysm exclusion is a validated technique to prevent aneurysm rupture. Long-term results highlight technique limitations and new aspects of ...

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14.3K Views.  Hôpital X. Bichat, AP-HP, Paris. Histological and biochemical modifications after aneurysm endograft exclusion are still unclear. We describe a new model of endograft implantation on a murine aneurysm. Through thrombus analysis with and without persistant circulating blood stream interface, and new endovascular biomaterials evaluation, this model will help to better understand endovascular aneurysm exclusion pathobiology.

Video: A New Murine Model of Endovascular Aortic Aneurysm Repair

Reproducable Paraplegia by Thoracic Aortic Occlusion in a Murine Model of Spinal Cord Ischemia-reperfusion

Background 
Lower extremity paralysis continues to complicate aortic interventions. The lack of understanding of the underlying pathology has hindered advancements to decrease the occurrence this injury.&#160;The current model demonstrates reproducible lower&#160;extremity paralysis following thoracic aortic occlusion.
Methods 
Adult male C57BL6 mice were anesthetized with isoflurane. Through a cervicosternal incision the aorta was exposed. The descending thoracic aorta and left subclavian arteries were identified without entrance into pleural space. Skeletonization of these arteries was followed by immediate closure (Sham) or occlusion for 4 min (moderate ischemia) or 8 min (prolonged ischemia). The sternotomy and skin were closed and the mouse was transferred to warming bed for recovery.&#160; Following recovery, functional analysis was obtained at 12 hr intervals until 48 hr.
Results 
Mice that underwent sham surgery showed no observable hind&#160;limb deficit. Mice subjected to moderate ischemia for 4 min had minimal functional deficit at 12 hr followed by progression to complete paralysis at 48 hr. Mice subjected to prolonged ischemia had an immediate paralysis with no observable hind-limb movement at any point in the postoperative period. There was no observed intraoperative or post&#160;operative mortality.
Conclusion 
Reproducible lower extremity paralysis whether immediate or delayed can be achieved in a murine model. Additionally, by using a median sternotomy and careful dissection, high survival rates, and reproducibility can be achieved.

The lack of mechanistic understanding of spinal cord ischemia-reperfusion injury has hindered further adjuncts to prevent paraplegia following high risk aortic operations. Thus, the development of animal models is imperative. This manuscript demonstrates reproducible lower extremity paralysis following thoracic aortic occlusion in a murine model.

Background
Lower extremity paralysis continues to complicate aortic interventions. The lack of understanding of the underlying pathology has hindered ...

Open Tracheostomy Gastric Acid Aspiration Murine Model of Acute Lung Injury Results in Maximal Acute Nonlethal Lung Injury

Acid pneumonitis is a major cause of sterile acute lung injury (ALI) in humans. Acid pneumonitis spans the clinical spectrum from asymptomatic to acute respiratory distress syndrome (ARDS), characterized by neutrophilic alveolitis, and injury to both alveolar epithelium and vascular endothelium. Clinically, ARDS is defined by acute onset of hypoxemia, bilateral patchy pulmonary infiltrates and non-cardiogenic pulmonary edema. Human studies have provided us with valuable information about the physiological and inflammatory changes in the lung caused by ARDS, which has led to various hypotheses about the underling mechanisms. Unfortunately, difficulties determining the etiology of ARDS, as well as a wide range of pathophysiology have resulted in a lack of critical information that could be useful in developing therapeutic strategies.
Translational animal models are valuable when their pathogenesis and pathophysiology accurately reproduce a concept proven in both in vitro and clinical settings. Although large animal models (e.g., sheep) share characteristics of the anatomy of human trachea-bronchial tree, murine models provide a host of other advantages including: low cost; short reproductive cycle lending itself to greater data acquisition; a well understood immunologic system; and a well characterized genome leading to the availability of a variety of gene deletion and transgenic strains. A robust model of low pH induced ARDS requires a murine ALI that targets mainly the alveolar epithelium, secondarily the vascular endothelium, as well as the small airways leading to the alveoli. Furthermore, a reproducible injury with wide differences between different injurious and non-injurious insults is important.
The murine gastric acid aspiration model presented here using hydrochloric acid employs an open tracheostomy and recreates a pathogenic scenario that reproduces the low pH pneumonitis injury in humans. Additionally, this model can be used to examine interaction of a low pH insult with other pulmonary injurious entities (e.g., food particles, pathogenic bacteria).

This protocol induces acute lung injury in a mouse that has close fidelity to the pathogenesis of acid pneumonitis observed in humans. We generate a maximal acute nonlethal low pH lung injury and account for differences in rodent-human anatomic respiratory structure using an open tracheostomy coupled with circumferential pressure release.

Acid pneumonitis is a major cause of sterile acute lung injury (ALI) in humans. Acid pneumonitis spans the clinical spectrum from asymptomatic to acute ...

Reproducible Arterial Denudation Injury by Infrarenal Abdominal Aortic Clamping in a Murine Model

Percutaneous vascular interventions uniformly result in arterial denudation injuries that subsequently lead to thrombosis and restenosis. These complications can be attributed to impairments in re-endothelialization within the wound margins. Yet, the cellular and molecular mechanisms of re-endothelialization remain to be defined. While several animal models to study re-endothelialization after arterial denudation are available, few are performed in the mouse because of surgical limitations. This undermines the opportunity to exploit transgenic mouse lines and investigate the contribution of specific genes to the process of re-endothelialization. Here, we present a step-by-step protocol for creating a highly reproducible murine model of arterial denudation injury in the infrarenal abdominal aorta using external vascular clamping. Immunocytochemical staining of injured aortas for fibrinogen and &#946;-catenin demonstrate the exposure of a pro-thrombotic surface and the border of intact endothelium, respectively. The method presented here has the advantages of speed, excellent overall survival rate, and relative technical ease, creating a uniquely practical tool for imposing arterial denudation injury in transgenic mouse models. Using this method, investigators may elucidate the mechanisms of re-endothelialization under normal or pathological conditions.

Understanding the cellular and molecular mechanisms of re-endothelialization following arterial denudation injury is of paramount importance in preventing thrombosis and restenosis of arteries. Here we describe a protocol for reproducible arterial denudation injury of the infrarenal abdominal aorta. The procedure was developed to investigate the underlying mechanisms that regulate endothelial regeneration using mouse models.

Percutaneous vascular interventions uniformly result in arterial denudation injuries that subsequently lead to thrombosis and restenosis. These ...

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 ...

Quantitative Micro-CT Analysis of Aortopathy in a Mouse Model of &#946;-aminopropionitrile-induced Aortic Aneurysm and Dissection

Aortic aneurysm and dissection is associated with significant morbidity and mortality in the population and can be highly lethal. While animal models of aortic disease exist, in vivo imaging of the vasculature has been limited. In recent years, micro-computerized tomography (micro-CT) has emerged as a preferred modality for imaging both large and small vessels both in vivo and ex vivo. In conjunction with a method of vascular casting, we have successfully used micro-CT to characterize the frequency and distribution of aortic pathology in &#946;-aminopropionitrile-treated C57/Bl6 mice. Technical limitations of this method include variations in the quality of the perfusion introduced by poor animal preparation, the application of proper methodologies for vessel size quantification, and the non-survivability of this procedure. This article details a methodology for the intravascular perfusion of a lead-based radiopaque silicone rubber for the quantitative characterization of aortopathy in a mouse model of aneurysm and dissection. In addition to visualizing aortic pathology, this method may be used for examining other vascular beds in vivo or vascular beds removed post-mortem.

Quantitative Micro-CT Analysis of Aortopathy in a Mouse Model of &amp;#946;-aminopropionitrile-induced Aortic Aneurysm and Dissection

This article describes a detailed methodology of using a radiopaque lead-based silicone rubber to perfuse the murine vasculature for aortic diameter quantification in a mouse model of aortic aneurysm and dissection.

Aortic aneurysm and dissection is associated with significant morbidity and mortality in the population and can be highly lethal. While animal models of ...

Murine Cervical Aortic Transplantation Model using a Modified Non-Suture Cuff Technique

With the introduction of powerful immunosuppressive protocols, distinct advances are possible in the prevention and therapy of acute rejection episodes. However, only minor improvement in the long-term results of transplanted solid organs could be observed over the past decades. In this context, chronic allograft vasculopathy (CAV) still represents the leading cause of late organ failure in cardiac, renal and pulmonary transplantation.
Thus far, the underlying pathogenesis of CAV development remains unclear, explaining why effective treatment strategies are presently missing and emphasizing a need for relevant experimental models in order to study the underlying pathophysiology leading to CAV formation. The following protocol describes a murine heterotopic cervical aortic transplantation model using a modified non-suture cuff technique. In this technique, a segment of the thoracic aorta is interpositioned in the right common carotid artery. With the use of the non-suture cuff technique, an easy to learn and reproducible model can be established, minimizing the possible heterogeneity of sutured vascular micro anastomoses.

Here, we present a protocol of heterotopic aortic transplantation in mice using the non-suture cuff technique in a cervical murine model. This model can be used to study the underlying pathology of chronic allograft vasculopathy (CAV) and can help evaluate new therapeutic agents in order to prevent its formation.

With the introduction of powerful immunosuppressive protocols, distinct advances are possible in the prevention and therapy of acute rejection episodes. ...

Murine Surgical Model of Topical Elastase Induced Descending Thoracic Aortic Aneurysm

According to the Center for Disease Control, aortic aneurysms (AAs) were considered a leading cause of death in all races and both sexes from 1999-2016. An aneurysm forms as a result of progressive weakening and eventual dilation of the aorta, which can rupture or tear once it reaches a critical diameter. Aneurysms of the descending aorta in the chest, called descending thoracic aortic aneurysms (dTAA), make up a large proportion of aneurysm cases in the United States. Uncontained dTAA rupture is almost universally lethal, and elective repair has a high rate of morbidity and mortality. The purpose of our model is to study dTAA specifically, to elucidate the pathophysiology of dTAA and to search for molecular targets to halt the growth or reduce the size of dTAA. By having a murine model to study thoracic pathology precisely, targeted therapies can be developed to specifically test dTAA. The method is based on the placement of porcine pancreatic elastase (PPE) directly on the outer murine aortic wall after surgical exposure. This creates a destructive and inflammatory reaction, which weakens the aortic wall and allows for aneurysm formation over weeks to months. Though murine models possess limitations, our dTAA model produces robust aneurysms of predictable size. Furthermore, this model can be used to test genetic and pharmaceutical targets which may arrest dTAA growth or prevent rupture. In human patients, interventions such as these could help avoid aneurysm rupture, and difficult surgical intervention.

We describe a surgical protocol to consistently induce robust descending thoracic aortic aneurysms in mice. The procedure involves left thoracotomy, thoracic aorta exposure, and placement of a sponge soaked in porcine pancreatic elastase on the aortic wall.

According to the Center for Disease Control, aortic aneurysms (AAs) were considered a leading cause of death in all races and both sexes from 1999-2016. ...

Porcine Model of Infrarenal Abdominal Aortic Aneurysm

Large animal models to study abdominal aortic aneurysms are sparse. The purpose of this model is to create reproducible, clinically significant infrarenal abdominal aortic aneurysms (AAA) in swine. To achieve this, we use a combination of balloon angioplasty, elastase and collagenase, and a lysyl oxidase inhibitor, called &#946;-aminopropionitrile (BAPN), to create clinically significant infrarenal aortic aneurysms, analogous to human disease.
Noncastrated male swine are fed BAPN for 7 days prior to surgery to achieve a steady state in the blood. A midline laparotomy is performed and the infrarenal aorta is circumferentially dissected. An initial measurement is recorded prior to aneurysm induction with a combination of balloon angioplasty, elastase (500 units)/collagenase (8000 units) perfusion, and topical elastase application. Swine are fed BAPN daily until terminal procedure on either postoperative day 7, 14, or 28, at which time the aneurysm is measured, and tissue procured. BAPN + surgery pigs are compared to pigs that underwent surgery alone.
Swine treated with BAPN and surgery had a mean aortic dilation of 89.9% &#177; 47.4% at day 7, 105.4% &#177; 58.1% at day 14, and 113.5% &#177; 30.2% at day 28. Pigs treated with surgery alone had significantly smaller aneurysms compared to BAPN + surgery animals at day 28 (p &#60; 0.0003). The BAPN + surgery group had macroscopic and immunohistochemical evidence of end stage aneurysmal disease.
Clinically significant infrarenal AAA can be induced using balloon angioplasty, elastase/collagenase perfusion and topical application, supplemented with oral BAPN. This model creates large, clinically significant AAA with hallmarks of human disease. This has important implications for the elucidation of AAA pathogenesis and testing of novel therapies and devices for the treatment of AAA. Limitations of the model include variation in BAPN ingested by swine, quality of elastase perfusion, and cost of BAPN.&#160;

This novel model creates robust infrarenal abdominal aortic aneurysms in swine using a combination of balloon angioplasty, elastase/collagenase perfusion, topical elastase application, and oral compound &#946;-aminopropionitrile administration, which interferes with collagen cross-linking.

Large animal models to study abdominal aortic aneurysms are sparse. The purpose of this model is to create reproducible, clinically significant infrarenal ...

A Murine Model of Hemodialysis Access-Related Hand Dysfunction

Chronic kidney disease is a major public health problem, and the prevalence of end-stage renal disease (ESRD) requiring chronic renal replacement therapies such as hemodialysis continues to increase. Autogenous arteriovenous fistula (AVF) placement remains a primary vascular access option for ESRD patients. Unfortunately, approximately half of the hemodialysis patients experience dialysis access-related hand dysfunction (ARHD), ranging from subtle paresthesia to digital gangrene. Notably, the underlying biologic drivers responsible for ARHD are poorly understood, and no adequate animal model exists to elucidate the mechanisms and/or develop novel therapeutics for the prevention/treatment of ARHD. Herein, we describe a new mouse model in which an AVF is created between the left common iliac artery and vein, thereby facilitating the assessment of limb pathophysiology. The microsurgery includes vessel isolation, longitudinal venotomy, creation of arteriovenous anastomosis, and venous reconstruction. Sham surgeries include all the critical steps except for AVF creation. Iliac AVF placement results in clinically relevant alterations in central hemodynamics, peripheral ischemia, and impairments in hindlimb neuromotor performance. This novel preclinical AVF model provides a useful platform that recapitulates common neuromotor perturbations reported by hemodialysis patients, allowing researchers to investigate the mechanisms of ARHD pathophysiology and test potential therapeutics.

This protocol details the surgical steps of murine common iliac arteriovenous fistula creation. We developed this model to study hemodialysis access-related limb pathophysiology.

Chronic kidney disease is a major public health problem, and the prevalence of end-stage renal disease (ESRD) requiring chronic renal replacement ...

Drug Treatment by Central Venous Catheter in a Mouse Model of Angiotensin II Induced Abdominal Aortic Aneurysm and Monitoring by 3D Ultrasound

Since pharmaceutical treatment options are lacking in the clinical management of abdominal aortic aneurysm (AAA), animal models, in particular mouse models, are applied to advance the understanding of the disease pathogenesis and to identify potential therapeutic targets. Testing novel drug candidates to block AAA growth in these models generally requires repeated drug administration during the time course of the experiment. Here, we describe a compiled protocol for AAA induction, insertion of an intravenous catheter to facilitate prolonged therapy, and serial AAA monitoring by 3D ultrasound. Aneurysms are induced in apolipoprotein E (ApoE) deficient mice by angiotensin II release over 28 days from osmotic mini-pumps implanted subcutaneously into the mouse back. Subsequently, the surgical procedure for external jugular vein catheterization is conducted to allow for daily intravenous drug treatment or repeated blood sampling via a subcutaneous vascular access button. Despite the two dorsal implants, the monitoring of AAA development is readily facilitated by sequential semi-automated 3D ultrasound analysis, which yields comprehensive information on the expansion of aortic diameter and volume and on aneurysm morphology, as illustrated by experimental examples.

This protocol describes the consecutive implantation of an osmotic pump to induce abdominal aortic aneurysm by angiotensin II release in apolipoprotein E (ApoE) deficient mice and of a vascular access port with a jugular vein catheter for repeated drug treatment. Monitoring of aneurysm development by 3D ultrasound is effectively conducted despite dorsal implants.

Since pharmaceutical treatment options are lacking in the clinical management of abdominal aortic aneurysm (AAA), animal models, in particular mouse ...