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>
 <td></td>
 </tr>
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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 ...

a-new-murine-model-of-endovascular-aortic-aneurysm-repair

Research

JoVE Journal

Medicine

14.3K vues.  Hôpital X. Bichat, AP-HP, Paris. Modifications histologiques et biochimiques après anévrisme exclusion d'endoprothèse sont encore mal connues. Nous décrivons un nouveau modèle d'implantation d'une endoprothèse anévrisme murin. Grâce à l'analyse thrombus avec et sans circulation persistante interface de flux sanguin, et nouvelle évaluation des biomatériaux endovasculaire, ce modèle permettra de mieux comprendre endovasculaire anévrisme exclusion pathobiology.

Vidéo: A New Murine Model of Endovascular Aortic Aneurysm Repair

Microsurgical Venous Pouch Arterial-Bifurcation Aneurysms in the Rabbit Model: Technical Aspects

For ruptured human cerebral aneurysms endovascular embolization has become an equivalent alternative to aneurysm clipping.1 However, large clinical trials have shown disappointing long-term results with unacceptable high rates of aneurysm recanalization and delayed aneurysm rupture.2 To overcome these problems, animal experimental studies are crucial for the development of better endovascular devices.3-5
Several animal models in rats, rabbits, canines and swine are available.6-8 Comparisons of the different animal models showed the superiority of the rabbit model with regard to hemodynamics and comparability of the coagulation system and cost-effectiveness.9-11 
The venous pouch arterial bifurcation model in rabbits is formed by a venous pouch sutured into an artificially created true bifurcation of both common carotid arteries (CCA). The main advantage of this model are true bifurcational hemodynamics.12 The major drawbacks are the sofar high microsurgical technical demands and high morbidity and mortality rates of up to 50%.13 These limitations have resulted in less frequent use of this aneurysm model in the recent years. These shortcomings could be overcome with improved surgical procedures and modified peri- and postoperative analgetic management and anticoagulation.14-16 Our techniques reported in this paper demonstrate this optimized technique for microsurgical creation of arterial bifurcation aneurysms.

An optimized technique for the microsurgical creation of arterial bifurcation aneurysms mimicking bifurcation human cerebral aneurysms is described. A venous pouch is sutured into an artificially created true bifurcation of both common carotid arteries. Facilitated microsurgical techniques and aggressive postoperative anticoagulation and analgesia lead to minimized morbidity rates and high aneurysm patency rates.

For ruptured human cerebral aneurysms endovascular embolization has become an equivalent alternative to aneurysm clipping.1 However, large clinical trials ...

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 ...

Murine Model of Femoral Artery Wire Injury with Implantation of a Perivascular Drug Delivery Patch

Percutaneous interventions including balloon angioplasty and stenting have been used to restore blood flow in vessels with occlusive vascular disease. While these therapies lead to the rapid restoration of blood flow, these technologies remain limited by restenosis in the case of bare metal stents and angioplasty, or reduced healing and possibly enhanced risk of thrombosis in the case of drug eluting stents. A key pathophysiological mechanism in the formation of restenosis is intimal hyperplasia caused by the activation of vascular smooth muscle cells and inflammation due to arterial stretch and injury. Surgeries that induce arterial injury in genetically modified mice are useful for the mechanistic study of the vascular response to injury but are often technically challenging to perform in mouse models due to the their small size and lack of appropriate sized devices. We describe two approaches for a surgical technique that induces endothelial denudation and arterial stretch in the femoral artery of mice to produce robust neointimal hyperplasia. The first approach creates an arteriotomy in the muscular branch of the femoral artery to obtain vascular access. Following wire injury this arterial branch is ligated to close the arteriotomy. A second approach creates an arteriotomy in the main femoral artery that is later closed through localized cautery. This method allows for vascular access through a larger vessel and, consequently, provides a less technically demanding procedure that can be used in smaller mice. Following either method of arterial injury, a degradable drug delivery patch can be placed over or around the injured artery to deliver therapeutic agents.

We describe a surgical technique that produces wire injury in the femoral artery of mice to induce neointimal hyperplasia to serve as a model testing system for the perivascular delivery of therapeutic compounds for the inhibition of restenosis.

Percutaneous interventions including balloon angioplasty and stenting have been used to restore blood flow in vessels with occlusive vascular disease. ...

A Murine Model of Arterial Restenosis: Technical Aspects of Femoral Wire Injury

Cardiovascular disease caused by atherosclerosis is the leading cause of death in the developed world. Narrowing of the vessel lumen, due to atherosclerotic plaque development or the rupturing of established plaques, interrupts normal blood flow leading to various morbidities such as myocardial infarction and stroke. In the clinic endovascular procedures such as angioplasty are commonly performed to reopen the lumen. However, these treatments inevitably damage the vessel wall as well as the vascular endothelium, triggering an excessive healing response and the development of a neointimal plaque that extends into the lumen causing vessel restenosis (re-narrowing). Restenosis remains a major cause of failure of endovascular treatments for atherosclerosis. Thus, preclinical animal models of restenosis are vitally important for investigating the pathophysiological mechanisms as well as translational approaches to vascular interventions. Among several murine experimental models, femoral artery wire injury is widely accepted as the most suitable for studies of post-angioplasty restenosis because it closely resembles the angioplasty procedure that injures both endothelium and vessel wall. However, many researchers have difficulty utilizing this model due to its high degree of technical difficulty. This is primarily because a metal wire needs to be inserted into the femoral artery, which is approximately three times thinner than the wire, to generate sufficient injury to induce prominent neointima. Here, we describe the essential surgical details to effectively overcome the major technical difficulties of this model. By following the presented procedures, performing the mouse femoral artery wire injury becomes easier. Once familiarized, the whole procedure can be completed within 20 min.

The mouse femoral artery wire injury model of restenosis is technically challenging. In this protocol we show the key technical details essential for successfully performing wire injury to induce consistent&#160;neointima for studies of restenosis.

Cardiovascular disease caused by atherosclerosis is the leading cause of death in the developed world. Narrowing of the vessel lumen, due to ...

A Novel Murine Model of Arteriovenous Fistula Failure: The Surgical Procedure in Detail

The arteriovenous fistula (AVF) still suffers from a high number of failures caused by insufficient remodeling and intimal hyperplasia from which the exact pathophysiology remains unknown. In order to unravel the pathophysiology a murine model of AVF-failure was developed in which the configuration of the anastomosis resembles the preferred situation in the clinical setting. A model was described in which an AVF is created by connecting the venous end of the branch of the external jugular vein to the side of the common carotid artery using interrupted sutures. At a histological level, we observed progressive stenotic intimal lesions in the venous outflow tract that is also seen in failed human AVFs. Although this procedure can be technically challenging due to the small dimensions of the animal, we were able to achieve a surgical success rate of 97% after sufficient training. The key advantage of a murine model is the availability of transgenic animals. In view of the different proposed mechanisms that are responsible for AVF failure, disabling genes that might play a role in vascular remodeling can help us to unravel the complex pathophysiology of AVF failure.

Here we present a murine model of arteriovenous fistula (AVF) failure in which a clinically relevant anastomotic configuration is incorporated. This model can be used to study the pathophysiology and to test possible therapeutic interventions.

The arteriovenous fistula (AVF) still suffers from a high number of failures caused by insufficient remodeling and intimal hyperplasia from which the ...

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 ...

Arterial Pouch Microsurgical Bifurcation Aneurysm Model in the Rabbit

Endovascular treatment for intracranial aneurysms gained importance over the past decades, consequently there is an increased need of testing endovascular devices. Animal models respecting rheological, hemodynamic and aneurysm wall conditions are highly warranted. Therefore, the aim of the present study was to design a novel standardized and reproducible surgical technique to create autologous arterial pouch bifurcation aneurysms with non-modified and modified wall conditions in rabbits.
Bifurcation aneurysms were created by end-to-side anastomosis of the right on the left common carotid artery, both serving as parent arteries for the arterial pouch, which was microsurgically sewn on. Grafts were taken from the proximal right common carotid artery, either for the control (n = 7, immediate autologous re-implantation) or modified (n = 7, incubated with 100 international units elastase for 20 minutes before autologous re-implantation) group. Pouch and parent artery patency were controlled by fluorescence angiography immediately after creation. At follow-up (28 days), all rabbits underwent contrast enhanced magnetic resonance angiography and fluorescence angiography followed by aneurysm harvesting, macroscopic and histological evaluation.
A total of 16 female New Zealand White rabbits were operated upon. Two animals died prematurely. At follow-up, 85.72% of all aneurysms remained patent. Both groups revealed an increase in aneurysm size over time; this was more pronounced in the control group (6.48 &#177; 1.81 mm3 at time of creation vs. 19.85 &#177; 6.40 mm3 at follow-up, p = 0.037) than in the modified group (8.03 &#177; 1.08 mm3 at time of creation vs. 20.29 &#177; 6.16 mm3 at follow-up, p = 0.054).
Our findings demonstrate the adequacy of this new rabbit model which allows for the creation of bifurcation aneurysms with different wall conditions in a microsurgical approach. Given the excellent long-term patency and the property of aneurysm growth over time, this model may serve as an important tool for preclinical evaluation of novel endovascular therapies.

Developing and testing endovascular devices for intracranial aneurysm treatment is still of great importance. Most aneurysm models used today miss either the important characteristics of an arterial degenerated wall or the hemodynamics of a true bifurcation. Therefore, we aimed to design a novel arterial pouch bifurcation model in rabbits.

Endovascular treatment for intracranial aneurysms gained importance over the past decades, consequently there is an increased need of testing endovascular ...

Neuroscience

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 ...