Name: porcine model of infrarenal abdominal aortic aneurysm
Uploaded: 2019-11-21T13:00:00
Description: Watch this Scientific Journal Video about Porcine Model of Infrarenal Abdominal Aortic Aneurysm at JoVE.com

We thank Anthony Herring and Cindy Dodson for their knowledge and technical expertise.
Sources of Funding: 
Funding for this study was provided by the National Heart, Lung, and Blood Institute of the National Institute of Health under Award No. T32HL007849 and Grant Nos. R01HL081629-07 (G.R.U.) and R01HL124131-01 (G.R.U.).

Animal protocols were approved by the University of Virginia Institutional Animal Care and Use Committee (No. 3848).
NOTE: This model has been previously published by Cullen et al. and is a modified protocol described by Hynecek et al.8,15.
1. Animals
<ol>
	<li>Use non-castrated male swine weighing 20-30 kg for the experiments.</li>
	<li>In order to maximize the proportion of weight-based doses of BAPN ing...

<ol>
	<li>. Leading Causes of Death Reports, National and Regional, 1999 - 2016 Available from: <a target="_blank" href="https://webappa.cdc.gov/sasweb/ncipc/leadcause.html">https://webappa.cdc.gov/sasweb/ncipc/leadcause.html</a> (2018)</li><li>Erbel, R., 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=Diagnosis+and+management+of+aortic+dissection.">Diagnosis and management of aortic dissection.</a> European Heart Journal. 22 (18), 1642-1681 (2001).</li><li>Cameron, J., Cameron, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Current Surgical Therapy 11th edition. 11, 777-783 (2014).</li><li>. 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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=The+creation+of+an+infrarenal+aneurysm+within+the+native+abdominal+aorta+of+swine.">The creation of an infrarenal aneurysm within the native abdominal aorta of swine.</a> Surgery. 142 (2), 143-149 (2007).</li><li>Lu, 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=A+novel+chronic+advanced+stage+abdominal+aortic+aneurysm+murine+model.">A novel chronic advanced stage abdominal aortic aneurysm murine model.</a> Journal of Vascular Surgery. 66 (1), 232-242 (2017).</li><li>Barrow, M. V., Simpson, C. F., Miller, E. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lathyrism:+a+review.">Lathyrism: a review.</a> The Quarterly Review of Biology. 49 (2), 101-128 (1974).</li><li>Coulson, W. F., Linker, A., Bottcher, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lathyrism+in+swine.">Lathyrism in swine.</a> Archives of Pathology &amp; Laboratory Medicine. 87 (4), 411-417 (1969).</li><li>McCallum, H. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experimental+Lathyrism+in+Mice.">Experimental Lathyrism in Mice.</a> The Journal of Pathology and Bacteriology. 89, 625-636 (1965).</li><li>Behmoaras, J., 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=Differential+expression+of+lysyl+oxidases+LOXL1+and+LOX+during+growth+and+aging+suggests+specific+roles+in+elastin+and+collagen+fiber+remodeling+in+rat+aorta.">Differential expression of lysyl oxidases LOXL1 and LOX during growth and aging suggests specific roles in elastin and collagen fiber remodeling in rat aorta.</a> Rejuvenation Research. 11 (5), 883-889 (2008).</li><li>Davies, I., Schofield, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Connective+tissue+ageing:+the+influence+of+a+lathyrogen+(beta-aminopropionitrile)+on+the+life+span+of+female+C57BL/Icrfat+mice.">Connective tissue ageing: the influence of a lathyrogen (beta-aminopropionitrile) on the life span of female C57BL/Icrfat mice.</a> Experimental Gerontology. 15 (5), 487-494 (1980).</li><li>Cullen, 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=A+novel+swine+model+of+abdominal+aortic+aneurysm.">A novel swine model of abdominal aortic aneurysm.</a> Journal of Vascular Surgery. , (2018).</li><li>Marinov, G. R., 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=Can+the+infusion+of+elastase+in+the+abdominal+aorta+of+the+Yucatan+miniature+swine+consistently+produce+experimental+aneurysms.">Can the infusion of elastase in the abdominal aorta of the Yucatan miniature swine consistently produce experimental aneurysms.</a> Journal of Investigative Surgery. 10 (3), 129-150 (1997).</li><li>Pope, N. H., 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=Interleukin-6+Receptor+Inhibition+Prevents+Descending+Thoracic+Aortic+Aneurysm+Formation.">Interleukin-6 Receptor Inhibition Prevents Descending Thoracic Aortic Aneurysm Formation.</a> Annals of Thoracic Surgery. 100 (5), 1620-1626 (2015).</li><li>Johnston, W. F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetic+and+pharmacologic+disruption+of+interleukin-1beta+signaling+inhibits+experimental+aortic+aneurysm+formation.">Genetic and pharmacologic disruption of interleukin-1beta signaling inhibits experimental aortic aneurysm formation.</a> Arteriosclerosis, Thrombosis, and Vascular Biology. 33 (2), 294-304 (2013).</li><li>Johnston, W. F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inhibition+of+interleukin-1beta+decreases+aneurysm+formation+and+progression+in+a+novel+model+of+thoracic+aortic+aneurysms.">Inhibition of interleukin-1beta decreases aneurysm formation and progression in a novel model of thoracic aortic aneurysms.</a> Circulation. 130 (11), 51-59 (2014).</li><li>Ruddy, J. M., Jones, J. A., Spinale, F. G., Ikonomidis, J. 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A novel model of infrarenal AAA in swine was created using a combination of balloon angioplasty, perfusion and topical elastase, and dietary as BAPN. Using this model, aortic dilation of &#62;100% was achieved with gross and histologic characteristics of chronic human aneurysmal disease. This model provides a gateway to further understand the complex pathophysiology of AAA and translate potential therapies to human disease.
Prior models of AAA in swine have been achieved with modest success. M...

According to the Center for Disease Control (CDC), aortic aneurysms (AA) are a leading cause of death in the United States and represent a significant disease burden1. An aortic aneurysm is defined as a dilation of a discrete portion of the vessel lumen by over 50%2. A subset of AA in the abdomen, referred to as abdominal aortic aneurysms (AAA) are a growing concern. AAA remain clinically silent until impending rupture or dissection, with acute onset, severe abdominal pain generally being the only presenting symptom3,4. Rupture of AAA is almost always fatal with a mortality rate of 90%5. Open or endovascular surgery is the only therapeutic option for patients, and can be a highly morbid procedure. Importantly, AAA are one of the few cardiovascular diseases with no medical therapy for cure.
To date, much of the research on AAA pathogenesis has focused on rodent models, using elastase, which is an enzyme that degrades elastin found within the aortic media, to induce aneurysms.6,7 However, the clinical translatability of small animal models to human aneurysmal disease is restricted, as evaluation of structural changes in the aorta, and altered hemodynamics are limited due to size. Because of anatomical and size similarity, the porcine circulatory system correlates better with human biology than rodents8. Large animal models allow further understanding of cellular mechanisms of the disease process, can be used develop novel treatments at therapeutic doses for large mammals, and test mechanical repair devices, which would not be feasible in small animal models. Additionally, the acute nature of rodent models does not replicate the chronicity and pathologic characteristics of human aneurysmal disease.
The combination of elastase and a compound called &#946;-aminopropionitrile (BAPN) has revolutionized murine AAA models, by creating aneurysms that are larger and contain sequela of chronic aneurysmal disease, including mural thrombus, dissection, and rupture9. BAPN is an inhibitor of lysyl oxidase, which is essential for collagen crosslinking, a crucial component of the aortic wall10,11,12. Lysyl oxidase activity decreases with aging and given the association of age and the chronic nature of complicated AA, BAPN has great potential to experimentally mimic the effects of aging9,13,14. The use of BAPN and its ability to replicate chronic disease in a subacute setting offers a novel advantage over alternative large animal models of AAA. Compared to other established porcine AAA models, this model creates the largest aneurysms with hallmarks of end-stage disease, and the results have been previously published8,11,15.
While conferring certain advantages, significant resources and investment are required to successfully complete this model that may deter some investigators. Among these resources include access to operating rooms, qualified surgeons and anesthesia providers, animal housing, and veterinary staff to assist with post-operative care. Additionally, the cost of BAPN may be prohibitively expensive for some labs.
Few large animal models exist to study the complex pathophysiology of AAA formation and translate to human disease. Large animal models of AAA are critical to help assess the viability of novel technologies and treatments for human disease. Therefore, the purpose of this study was to create a reproducible model of advanced stage infrarenal AAA in swine. The rationale for the use of BAPN and elastase swine model is to better understand the pathophysiology of AAA by mimicking the chronic nature and sequela of human aneurysmal disease in an acute or subacute setting, as well as to test novel therapies and devices for AAA treatment.

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			<td height="21" style="height:21px;width:216px;">Arrow Ergo Pack System</td>
			<td style="width:141px;">Arrow</td>
			<td style="width:119px;">CDC-21242-X1A</td>
			<td style="width:317px;">Just need 7 Fr dilator</td>
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			<td height="42" style="height:42px;width:216px;">Atlas PTA Balloon dilation catheter</td>
			<td style="width:141px;">Bard</td>
			<td style="width:119px;">AT-120184</td>
			<td>16 mm x 4 cm x 120 cm</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Bovie electrocautery</td>
			<td style="width:141px;">Bovie Medical</td>
			<td style="width:119px;">A2350</td>
			<td></td>
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			<td height="21" style="height:21px;width:216px;">Collagenase Type 1 (5 gm)</td>
			<td style="width:141px;">Worthington</td>
			<td style="width:119px;">LS004196</td>
			<td></td>
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			<td height="21" style="height:21px;width:216px;">Crile Needle drviers</td>
			<td style="width:141px;">MFI medical</td>
			<td style="width:119px;">61-2201</td>
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			<td height="21" style="height:21px;width:216px;">DeBakey Atraumatic Forceps</td>
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			<td style="width:119px;">52-4977</td>
			<td></td>
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			<td height="42" style="height:42px;width:216px;">DeBakey Peripheral Vascular Clamp</td>
			<td style="width:141px;">Medline</td>
			<td style="width:119px;">MDS1318119</td>
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			<td height="63" style="height:63px;width:216px;">Glidewire</td>
			<td style="width:141px;">Terumo Interventional Systems</td>
			<td style="width:119px;">GS3506</td>
			<td>outer Wire diameter 0.035 mm, Length 150 cm</td>
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			<td height="44" style="height:45px;">GraphPad Prism 6</td>
			<td style="width:141px;">GraphPad Software Inc. La Jolla, Calif)</td>
			<td style="width:119px;"></td>
			<td>statistical software</td>
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			<td height="21" style="height:21px;width:216px;">Metzenbaum Scissors</td>
			<td style="width:141px;">MFI medical</td>
			<td style="width:119px;">61-0004</td>
			<td></td>
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		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Mayo-Hegar Needle Holder</td>
			<td style="width:141px;">tiger medical</td>
			<td style="width:119px;">N407322</td>
			<td></td>
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			<td height="21" style="height:21px;width:216px;">Micropuncture Introducer Set</td>
			<td style="width:141px;">Cook</td>
			<td style="width:119px;">G47946</td>
			<td></td>
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			<td height="42" style="height:42px;width:216px;">Mixter Forceps, Standard Grade, Right angle</td>
			<td style="width:141px;">Cole-Parmer</td>
			<td style="width:119px;">UX-10818-16</td>
			<td></td>
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			<td height="21" style="height:21px;width:216px;">Monocryl suture</td>
			<td style="width:141px;">Ethicon</td>
			<td style="width:119px;">Y496G-BX</td>
			<td>4-0 monocryl</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:216px;">PDS II suture</td>
			<td style="width:141px;">Ethicon</td>
			<td style="width:119px;">D8926</td>
			<td>Number 1 looped</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Porcine Pancreatic Elastase</td>
			<td style="width:141px;">Sigma-Aldrich</td>
			<td style="width:119px;">E0258-50 MG</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Satinsky Vascular Clamps</td>
			<td style="width:141px;">Medline</td>
			<td style="width:119px;">MDs5632515</td>
			<td></td>
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		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Suction canister</td>
			<td style="width:141px;">Cardinal Health</td>
			<td style="width:119px;">65651212</td>
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			<td height="21" style="height:21px;width:216px;">Schuco Aspirator</td>
			<td style="width:141px;">MFI medical</td>
			<td style="width:119px;">S430A</td>
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			<td height="21" style="height:21px;width:216px;">Vicryl suture</td>
			<td style="width:141px;">Ethicon</td>
			<td style="width:119px;">J789D-SD</td>
			<td>2-0 vicryl</td>
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			<td height="21" style="height:21px;width:216px;">Yankauer Suction tube</td>
			<td style="width:141px;">Sklarcorp</td>
			<td style="width:119px;">07-1801</td>
			<td></td>
		</tr>
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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;

All statistical analyses were performed using Fisher exact test or chi squared test as appropriate. Data values are reported as mean aortic dilation (%) &#177; standard deviation (%). Statistical significance was set P &#60; 0.05. The combination of BAPN and surgery providing elastase treatment (surgery/elastase) creates more robust and reproducible AAA in swine at day 28 compared to those treated with surgery and elastase alone (mean aortic dilation (%) &#177; standard deviation (%): 113.5% &#177; 30.2% (n = 8) versus 5...

Watch this Scientific Journal Video about Porcine Model of Infrarenal Abdominal Aortic Aneurysm at JoVE.com

Porcine Model of Infrarenal Abdominal Aortic Aneurysm

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 ...

Few large animal models exist to study abdominal aortic aneurysms, but these models are critical to assessing the viability of novel technologies and treatments for human disease. The combination of elastase and a compound called BAPN creates aneurysms that are large and contain sequelae of chronic aneurysmal disease, such as thrombi, dissections, and ruptures. Demonstrating the procedure with me will be Doctors Jolian Dahl and Erik Scott, fellow surgical residents.Seven days before the surgery, provide 20 to 30 kilogram non-castrated male swine with standard chow supplemented with BAPN given in weight-based dose and mixed in whole milk plain yogurt. On the day of the procedure, confirm an appropriate level of sedation and drape the pig in the standard fashion. Ensure all of the necessary instruments are organized and ready on a sterile draped table.This includes the instrument tray, micropuncture introducer kit, 025-millimeter Glidewire, saline flushed tested 16-millimeter percutaneous transluminal angioplasty balloon, and connected pressure syringe. Using electrocautery, perform a midline laparotomy to enter the abdominal cavity taking care to stay to the right of the penis and its shaft to avoid injury. Tuck one side of a saline soaked sterile blue towel into the left paracolic gutter, and then use it to cover the bowel to avoid desiccation before displacing the abdominal viscera to the pig's left exposing the retroperitoneum.While one operator retracts the sigmoid colon and rectum to the left, the other surgeon palpates for the aortic pulse to identify the appropriate site to incise the retroperitoneum. Tent the retroperitoneum and use electrocautery to incise and enter the retroperitoneum, facilitating access to the inferior vena cava and infrarenal abdominal aorta. Circumferentially dissect approximately three centimeters of the aorta at the midpoint between the right renal artery and aortic trifurcation to allow for baseline measurement of the aorta before full dissection causes aortic spasm.Take care to avoid injury to the right ureter. Once a short segment of the aorta has been exposed, use calipers to measure its diameter. After measurement, complete the circumferential dissection of the entire infrarenal aorta.Identify the caudal mesenteric artery on the anterior portion of the infrarenal aorta, which usually lies a few centimeters proximal to the aortic trifurcation and dissect.Clamp. And transect this artery. Administer 100 units per kilogram of unfractionated heparin sulfate intravenously.Use a 018-inch stainless steel wire guide from a micropuncture introducer set to cannulate the caudal mesenteric artery. Serially dilate the artery over the wire first with a 5 French micropuncture introducer, followed by a 7 French dilator. Leaving the 7 French introducer in place, replace the 018-inch wire with a 035-inch guidewire and remove the 7 French dilator, ensuring hemostasis by pinching or placing a finger over the cannulation site.Advance the 035-inch guidewire until approximately 30 centimeters of wire remains or resistance is encountered. Insert a 16-millimeter percutaneous transluminal angioplasty balloon over the wire into the infrarenal aorta. Once the balloon is inside the aorta, remove the guidewire and place a finger over the wire port of the balloon to prevent hemorrhage.Inflate the balloon while intermittently measuring the diameter of the dilated aorta with calipers until maximal dilation is approximately 80%greater than the baseline measurement. Deflate and adjust the depth of the balloon catheter before fully inflating to ensure that the dilated segment is at the midpoint of the dissected aorta. Once the desired dilation is achieved, turn the three-way stopcock between the pressure syringe and balloon catheter to off towards the balloon and leave the aorta dilated for 10 minutes.Replace the guidewire and then deflate and exchange the balloon for 7 French dilator, before removing the wire, and allowing for 10 minutes of reperfusion. Be sure to confirm the aortic pulse distal to the balloon dilated segment. At the end of the reperfusion, identify and clamp the previously dissected lumbar vessels to isolate the infrarenal aorta from systemic circulation to avoid systemic perfusion of the elastase.Cross clamp the aorta just distal to the renal vessels and proximal to the aortic trifurcation. Potts tourniquet the portion of aorta containing the 7 French dilator just proximal to the cannulation site with a vessel loop. Remove the wire and flush the isolated aortic segment with saline confirming no leakage of fluid.Connect 500 units of elastase and 8, 000 units of collagenase solution to the introducer. Perfuse the entire 30 milliliters of solution into the isolated aorta under constant manual pressure for 10 minutes. After 10 minutes, irrigate the solution from the aortic lumen with saline.And remove the introducer. Ligate the caudal mesenteric artery stump or place a 5-0 prolene repair suture if the stump was destroyed. And release the lumbar clamps, the distal clamp and the proximal clamp.Soak a two-by-five centimeter piece of surgical gauze with 20 milliliters of undiluted elastase and wrap the gauze around the intervened aorta for 10 minutes. After measuring the aorta with a caliper, irrigate the abdomen with saline. Replace the bowel.And close the fascia, deep dermal layer, and skin in three layers. Then inject 0.2 milligrams per kilogram of long-acting buprenorphine intramuscularly into the left thigh for postoperative analgesia. The combination of the BAPN and surgery providing elastase treatment creates a more robust and reproducible abdominal aortic aneurysm in swine at day 28 compared to animals treated with surgery and elastase alone.Abdominal aortic aneurysm grows progressively larger as time progresses, and evidence of chronic aneurysmal disease is evident in animals treated with BAPN and surgery with elastase, including intraluminal thrombus and atherosclerosis. Further, histologic evaluation demonstrates a significantly increased elastin fragmentation in BAPN-treated swine abdominal aortic aneurysm than in animals treated with surgery and elastase alone, as well as an increased collagen alteration. The induction of abdominal aortic aneurysms via laparotomy can be daunting for non-surgically trained investigators, and a team effort is required for this model to be successful.Remember that the sharp instruments used during this procedure can cause actual harm to the operators and to exercise caution when sharp needles or instruments are on the surgical field.

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Medicine

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.

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 ...

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 ...

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.

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 ...

Isometric Contractility Measurement of the Mouse Mesenteric Artery Using Wire Myography

The wire myograph technique is used to assess the contractility of vascular smooth muscles in response to depolarization, GPCR agonists/inhibitors and drugs. It is widely used in many studies on the physiological functions of vascular smooth muscle, the pathogenesis of vascular diseases such as hypertension, and the development of smooth muscle relaxant drugs. The mouse is a widely used model animal with a large pool of disease models and genetically modified strains. We introduced this method to measure the isometric contraction of mouse mesenteric artery in detail. A 1.4-mm segment of mouse mesenteric resistance artery was isolated and mounted on a myograph chamber by passing two steel wires through its lumen. After equilibration and normalization steps, the vessel segment was potentiated by a high-K+ solution twice prior to the contraction assay. As an example of the application of this method in drug development, we measured the relaxant effect of a novel natural substance, neoliensinine, isolated from a Chinese herb, embryos of the lotus seed (Nelumbo nucifera Gaertn.) on mouse mesenteric arteries. The vessel segments mounted on the myograph chamber were stimulated with a high-K+ solution. When the force tension reached a stable sustained phase, cumulative doses of neoliensinine were added to the chamber. We found that neoliensinine had a dose-dependent relaxant effect on smooth muscle contraction, thus suggesting that it bears potential activity against hypertension. In addition, as the vessel segment can survive at least 4 hours after mounting and maintain contractility induced by the high-K+ solution for many times, we suggest that the wire myograph system may be used for the time-consuming process of drug screening.

The wire myograph technique is used to investigate vascular smooth muscle functions and screen new drugs. We report a detailed protocol for measuring the isometric contractility of the mouse mesenteric artery and for screening new relaxants of vascular smooth muscle.

The wire myograph technique is used to assess the contractility of vascular smooth muscles in response to depolarization, GPCR agonists/inhibitors and ...

Ultrasound Imaging of the Thoracic and Abdominal Aorta in Mice to Determine Aneurysm Dimensions

Contemporary high-resolution ultrasound instruments have sufficient resolution to facilitate the measurement of mouse aortas. These instruments have been widely used to measure aortic dimensions in mouse models of aortic aneurysms. Aortic aneurysms are defined as permanent dilations of the aorta, which occur most frequently in the ascending and abdominal regions. Sequential measurements of aortic dimensions by ultrasound are the principal approach for assessing the development and progression of aortic aneurysms in vivo. Although many reported studies used ultrasound imaging to measure aortic diameters as a primary endpoint, there are confounding factors, such as probe position and cardiac cycle, that may impact the accuracy of data acquisition, analysis, and interpretation. The purpose of this protocol is to provide a practical guide on the use of ultrasound to measure the aortic diameter in a reliable and reproducible manner. This protocol introduces the preparation of mice and instruments, the acquisition of appropriate ultrasound images, and data analysis.

Ultrasound imaging has become a common modality to determine the luminal dimensions of thoracic and abdominal aortic aneurysms in mice. This protocol describes the procedure to acquire reliable and reproducible two-dimensional ultrasound images of the ascending and abdominal aorta in mice.

Contemporary high-resolution ultrasound instruments have sufficient resolution to facilitate the measurement of mouse aortas. These instruments have been ...

A Pre-Clinical Porcine Model of Orthotopic Heart Transplantation

Fifty-years following the first successful report, cardiac transplantation remains the gold-standard treatment for eligible patients with advanced heart failure. Multiple small-animal models of heart transplantation have been used to study the acute and long-term effects of novel therapies. However, few are tested and demonstrated success in clinical trials. It is of critical importance to evaluate new therapies in a clinically relevant large-animal model for efficient and reliable translation of basic studies&#39;&#160;findings. Here, we describe a pre-clinical large-animal (porcine) model of orthotopic heart transplantation that has been firmly established and previously used to investigate novel cardioprotective strategies. This procedure focuses on acute ischemia-reperfusion injury and is a reliable method to investigate novel interventions which have been tested and validated in smaller experimental models, such as the murine model. We demonstrate its usefulness in assessing cardiac performance during the early post-transplantation period and other potential possibilities enabled by the model.

Here, we describe a pre-clinical large-animal (porcine) model of orthotopic heart transplantation that has been firmly established and utilized to investigate novel cardioprotective strategies.

Fifty-years following the first successful report, cardiac transplantation remains the gold-standard treatment for eligible patients with advanced heart ...

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. ...

Establishment and Evaluation of a Porcine Vein Graft Disease Model

Venous graft disease (VGD) is the leading cause of coronary artery bypass graft (CABG) failure. Large animal models of CABG-VGD are needed for the investigation of disease mechanisms and the development of therapeutic strategies. 
To perform the surgery, we enter the cardiac chamber through the third intercostal space and carefully dissect the internal mammary vein and immerse it in normal saline. The right main coronary artery is then treated for ischemia. The target vessel is incised, a shunt plug is placed, and the distal end of the graft vein is anastomosed. The ascending aorta is partially blocked, and the proximal end of the graft vein is anastomosed after perforation. The graft vein is checked for patency, and the proximal right coronary artery is ligated. 
CABG surgery is performed in minipigs to harvest the left internal mammary vein for its use as a vascular graft. Serum biochemical tests are used to evaluate the physiological status of the animals after surgery. Ultrasound examination shows that the proximal, middle, and distal end of the graft vessel are unobstructed. In the surgical model, turbulent blood flow in the graft is observed upon histological examination after the CABG surgery, and venous graft stenosis associated with intimal hyperplasia is observed in the graft. The study here provides detailed surgical procedures for the establishment of a repeatable CABG-induced VGD model.

In this protocol, novel pig vein bypass grafting was performed through a small incision in the left chest wall without cardiopulmonary bypass. A postoperative pathology study was done, which showed intimal thickening.