Name: a new murine model of endovascular aortic aneurysm repair
Uploaded: 2013-07-07T14:00:00
Description: Watch this Scientific Journal Video about A New Murine Model of Endovascular Aortic Aneurysm Repair at JoVE.com

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 dis...

<ol>
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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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A., 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=Association+of+intraluminal+thrombus+in+abdominal+aortic+aneurysm+with+local+hypoxia+and+wall+weakening.">Association of intraluminal thrombus in abdominal aortic aneurysm with local hypoxia and wall weakening.</a> J. Vasc. Surg. 34, 291-299 (2001).</li><li>Kazi, 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=Influence+of+intraluminal+thrombus+on+structural+and+cellular+composition+of+abdominal+aortic+aneurysm+wall.">Influence of intraluminal thrombus on structural and cellular composition of abdominal aortic aneurysm wall.</a> J. Vasc. Surg. 38, 1283-1292 (2003).</li><li>Kuijper, P. 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Pathol. 168, 1022-1030 (2006).</li><li>Fontaine, V., 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=Role+of+leukocyte+elastase+in+preventing+cellular+re-colonization+of+the+mural+thrombus.">Role of leukocyte elastase in preventing cellular re-colonization of the mural thrombus.</a> Am. J. Pathol. 164, 2077-2087 (2004).</li><li>Sakalihasan, N., Delvenne, P., Nusgens, B. V., Limet, R., Lapiere, C. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Activated+forms+of+MMP2+and+MMP9+in+abdominal+aortic+aneurysms.">Activated forms of MMP2 and MMP9 in abdominal aortic aneurysms.</a> J. Vasc. Surg. 24, 127-133 (1996).</li><li>Alsac, J. 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=The+significance+of+endoleaks+in+thoracic+endovascular+aneurysm+repair.">The significance of endoleaks in thoracic endovascular aneurysm repair.</a> Ann. Vasc. Surg. 25, 345-351 (2011).</li><li>Buth, J., Harris, P. L., van Marrewijk, C., Fransen, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+significance+and+management+of+different+types+of+endoleaks.">The significance and management of different types of endoleaks.</a> Semin. Vasc. Surg. 16, 95-102 (2003).</li><li>Fransen, G. A., 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=Rupture+of+infra-renal+aortic+aneurysm+after+endovascular+repair:+a+series+from+EUROSTAR+registry.">Rupture of infra-renal aortic aneurysm after endovascular repair: a series from EUROSTAR registry.</a> Eur. J. Vasc. Endovasc. Surg. 26, 487-493 (2003).</li><li>van der Vaart, M. G., 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=Application+of+PET/SPECT+imaging+in+vascular+disease.">Application of PET/SPECT imaging in vascular disease.</a> Eur. J. Vasc. Endovasc. Surg. 35, 507-513 (2008).</li><li>Close, B., 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=Recommendations+for+euthanasia+of+experimental+animals:+Part+2.+DGXT+of+the+European+Commission.">Recommendations for euthanasia of experimental animals: Part 2. DGXT of the European Commission.</a> Lab. Anim. 31, 1-32 (1997).</li><li>Allaire, E., Guettier, C., Bruneval, P., Plissonnier, D., Michel, J. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell-free+arterial+grafts:+morphologic+characteristics+of+aortic+isografts,+allografts,+and+xenografts+in+rats.">Cell-free arterial grafts: morphologic characteristics of aortic isografts, allografts, and xenografts in rats.</a> J. Vasc. Surg. 19, 446-456 (1994).</li><li>Gawenda, M., Jaschke, G., Winter, S., Wassmer, G., Brunkwall, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endotension+as+a+result+of+pressure+transmission+through+the+graft+following+endovascular+aneurysm+repair--an+in+vitro+study.">Endotension as a result of pressure transmission through the graft following endovascular aneurysm repair--an in vitro study.</a> Eur. J. Vasc. Endovasc. Surg. 26, 501-505 (2003).</li><li>Delbosc, 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=Porphyromonas+gingivalis+Participates+in+Pathogenesis+of+Human+Abdominal+Aortic+Aneurysm+by+Neutrophil+Activation.+Proof+of+Concept+in+Rats.">Porphyromonas gingivalis Participates in Pathogenesis of Human Abdominal Aortic Aneurysm by Neutrophil Activation. Proof of Concept in Rats.</a> PLoS One. 6, e18679 (2011).</li><li>Trollope, A., Moxon, J. V., Moran, C. S., Golledge, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Animal+models+of+abdominal+aortic+aneurysm+and+their+role+in+furthering+management+of+human+disease.">Animal models of abdominal aortic aneurysm and their role in furthering management of human disease.</a> Cardiovasc Pathol. 20, 114-123 (2011).</li><li>Yamaguchi, T., 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=Factors+influencing+mortality+in+the+rat+elastase-induced-aneurysm+model.">Factors influencing mortality in the rat elastase-induced-aneurysm model.</a> J. Surg. Res. 94, 81-83 (2000).</li><li>von Bruhl, M. L., 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=Monocytes,+neutrophils,+and+platelets+cooperate+to+initiate+and+propagate+venous+thrombosis+in+mice+in+vivo.">Monocytes, neutrophils, and platelets cooperate to initiate and propagate venous thrombosis in mice in vivo.</a> J. Exp. Med. 209, 819-835 (2012).</li><li>Smith, P. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neutrophil+activation+and+mediators+of+inflammation+in+chronic+venous+insufficiency.">Neutrophil activation and mediators of inflammation in chronic venous insufficiency.</a> J. Vasc. Res. 36, 24-36 (1999).</li><li>Zaragoza, C., 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=Animal+models+of+cardiovascular+diseases.">Animal models of cardiovascular diseases.</a> J. Biomed. Biotechnol. 2011, 497841 (2011).</li><li>Kuivaniemi, H., Elmore, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Opportunities+in+abdominal+aortic+aneurysm+research:+epidemiology,+genetics,+and+pathophysiology.">Opportunities in abdominal aortic aneurysm research: epidemiology, genetics, and pathophysiology.</a> Ann. Vasc. Surg. 26 (12), 862-870 (2012).</li><li>Schanzer, A., 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=Predictors+of+abdominal+aortic+aneurysm+sac+enlargement+after+endovascular+repair.">Predictors of abdominal aortic aneurysm sac enlargement after endovascular repair.</a> Circulation. 123, 2848-2855 (2011).</li></ol>

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>
</tbody>
</table>

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...

Watch this Scientific Journal Video about A New Murine Model of Endovascular Aortic Aneurysm Repair at JoVE.com

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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Research

JoVE Journal

Medicine

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 ...

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 ...

A Mouse Fetal Skin Model of Scarless Wound Repair

Early in utero, but not in postnatal life, cutaneous wounds undergo regeneration and heal without formation of a scar. Scarless fetal wound healing occurs across species but is age dependent. The transition from a scarless to scarring phenotype occurs in the third trimester of pregnancy in humans and around embryonic day 18 (E18) in mice. However, this varies with the size of the wound with larger defects generating a scar at an earlier gestational age. The emergence of lineage tracing and other genetic tools in the mouse has opened promising new avenues for investigation of fetal scarless wound healing. However, given the inherently high rates of morbidity and premature uterine contraction associated with fetal surgery, investigations of fetal scarless wound healing in vivo require a precise and reproducible surgical model. Here we detail a reliable model of fetal scarless wound healing in the dorsum of E16.5 (scarless) and E18.5 (scarring) mouse embryos.

During mammalian development, early gestational skin wounds heal without a scar. Here we detail a reliable and reproducible model of fetal scarless wound healing in the cutaneous dorsum of E16.5 (scarless) and E18.5 (scarring) mouse embryos.

Early in utero, but not in postnatal life, cutaneous wounds undergo regeneration and heal without formation of a scar. Scarless fetal wound healing occurs ...

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 ...