Name: Advanced Abdominal Aortic Aneurysm Modeling in Mice by Combination of Topical Elastase and Oral ß-aminopropionitrile (Video) | JoVE Journal
Uploaded: 2024-07-26T13:30:00.000+00:00
Duration: 7 min 42 s
Description: Learn an advanced abdominal aortic aneurysm modeling method using topical elastase and oral BAPN in mice. This technique enables reliable study of aneurysm growth and rupture mechanisms.

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This investigation was supported by the National Heart Lung and Blood Institute (NHLBI) of the National Institutes of Health (NIH) under 1R01HL149404-01A1 (BL), and the Ruth L. Kirschstein National Research Service Award T32 HL 007936 to the University of Wisconsin-Madison Cardiovascular Research Center (JB). Figures were created or edited with Biorender.com. Statistical analysis was performed using GraphPad Prism 10 software.

Abdominal Aortic Aneurysm Development in Mice Using the Elastase and BAPN Method

<ol><li>Kent, K. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Clinical+practice.+Abdominal+aortic+aneurysms%5BTitle%5D)+AND+%22New+Engl+J+Med%22%5BJournal%5D)">Clinical practice. Abdominal aortic aneurysms.</a> New Engl J Med. 371 (22), 2101-2208 (2014).</li>
<li>Wanhainen, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((European+Society+for+Vascular+Surgery+Guidelines+on+the+management+of+aorto-iliac+abdominal+aortic+aneurysms%5BTitle%5D)+AND+%22Eur+J+Vasc+Endocasc+Surg%22%5BJournal%5D)">European Society for Vascular Surgery Guidelines on the management of aorto-iliac abdominal aortic aneurysms.</a> Eur J Vasc Endocasc Surg. 57 (1), 8-93 (2019).</li>
<li>Shimizu, K., Mitchell, R. N., Libby, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Inflammation+and+cellular+immune+responses+in+abdominal+aortic+aneurysms%5BTitle%5D)+AND+%22Arterioscler+Thromb+Vasc+Biol%22%5BJournal%5D)">Inflammation and cellular immune responses in abdominal aortic aneurysms.</a> Arterioscler Thromb Vasc Biol. 26 (5), 987-994 (2006).</li>
<li>Shen, Y. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Aortic+aneurysms+and+dissections+series%5BTitle%5D)+AND+%22ArteriosclerThromb+Vasc+Biol%22%5BJournal%5D)">Aortic aneurysms and dissections series.</a> ArteriosclerThromb Vasc Biol. 40 (3), e37-e46 (2020).</li>
<li>Stanley, J. C., Veith, F., Wakefield, T. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Current+Therapy+in+Vascular+and+Endovascular+Surgery+E-Book%5BTitle%5D)+AND+%22Elsevier+Health+Sciences%22%5BJournal%5D)">Current Therapy in Vascular and Endovascular Surgery E-Book.</a> Elsevier Health Sciences. , (2014).</li>
<li>Morgan, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Identifying+novel+mechanisms+of+abdominal+aortic+aneurysm+via+unbiased+proteomics+and+systems+biology%5BTitle%5D)+AND+%22Front+Cardiovasc+Med%22%5BJournal%5D)">Identifying novel mechanisms of abdominal aortic aneurysm via unbiased proteomics and systems biology.</a> Front Cardiovasc Med. 9, 889994(2022).</li>
<li>Yin, L., Kent, E. W., Wang, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Progress+in+murine+models+of+ruptured+abdominal+aortic+aneurysm%5BTitle%5D)+AND+%22Front+Cardiovasc+Med%22%5BJournal%5D)">Progress in murine models of ruptured abdominal aortic aneurysm.</a> Front Cardiovasc Med. 9, 950018(2022).</li>
<li>Lu, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((A+novel+chronic+advanced+stage+abdominal+aortic+aneurysm+murine+model%5BTitle%5D)+AND+%22J+Vasc+Surg%22%5BJournal%5D)">A novel chronic advanced stage abdominal aortic aneurysm murine model.</a> J Vasc Surg. 66 (1), 232-242 (2017).</li>
<li>Berman, A. G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Experimental+aortic+aneurysm+severity+and+growth+depend+on+topical+elastase+concentration+and+lysyl+oxidase+inhibition%5BTitle%5D)+AND+%22Sci+Rep%22%5BJournal%5D)">Experimental aortic aneurysm severity and growth depend on topical elastase concentration and lysyl oxidase inhibition.</a> Sci Rep. 12 (1), 99(2022).</li>
<li>Deaths, percent of total deaths, and death rates for the 15 leading causes of death in 5-year age groups, by race, and sex. Centers for Disease Control and Prevention. , Available from: 
 <a target="_blank" href="https://www.cdc.gov/nchs/nvss/mortality/lcwk1.htm">https://www.cdc.gov/nchs/nvss/mortality/lcwk1.htm</a> (2015).</li>
<li>Dansey, K. D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Epidemiology+of+endovascular+and+open+repair+for+abdominal+aortic+aneurysms+in+the+United+States+from+2004+to+2015+and+implications+for+screening%5BTitle%5D)+AND+%22J+Vasc+Surg%22%5BJournal%5D)">Epidemiology of endovascular and open repair for abdominal aortic aneurysms in the United States from 2004 to 2015 and implications for screening.</a> J Vasc Surg. 74 (2), 414-424 (2021).</li>
<li>Daugherty, A., Cassis, L. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Mouse+models+of+abdominal+aortic+aneurysms%5BTitle%5D)+AND+%22Arterioscler+Thromb+Vasc+Biol%22%5BJournal%5D)">Mouse models of abdominal aortic aneurysms.</a> Arterioscler Thromb Vasc Biol. 24 (3), 429-434 (2004).</li>
<li>Busch, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Translating+mouse+models+of+abdominal+aortic+aneurysm+to+the+translational+needs+of+vascular+surgery%5BTitle%5D)+AND+%22JVS+Vasc+Sci%22%5BJournal%5D)">Translating mouse models of abdominal aortic aneurysm to the translational needs of vascular surgery.</a> JVS Vasc Sci. 2, 219-234 (2021).</li>
<li>Anidjar, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Elastase-induced+experimental+aneurysms+in+rats%5BTitle%5D)+AND+%22Circulation%22%5BJournal%5D)">Elastase-induced experimental aneurysms in rats.</a> Circulation. 82 (3), 973-981 (1990).</li>
<li>Bhamidipati, C. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Development+of+a+novel+murine+model+of+aortic+aneurysms+using+peri-adventitial+elastase%5BTitle%5D)+AND+%22Surgery%22%5BJournal%5D)">Development of a novel murine model of aortic aneurysms using peri-adventitial elastase.</a> Surgery. 152 (2), 238-246 (2012).</li>
<li>Xue, C., Zhao, G., Zhao, Y., Chen, Y. E., Zhang, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Mouse+abdominal+aortic+aneurysm+model+induced+by+perivascular+application+of+elastase%5BTitle%5D)+AND+%22J+Vis+Exp%22%5BJournal%5D)">Mouse abdominal aortic aneurysm model induced by perivascular application of elastase.</a> J Vis Exp. (180), e63608(2022).</li>
</ol>

The authors of this manuscript have no conflicts of interest to declare.

Understanding the complex pathophysiology of AAA is critical for improving the management of aortic aneurysm disease. While newer strategies are actively developed to improve surgical outcomes, AAAs remain prevalent in our aging society and aneurysm rupture remains a leading cause of death in the United States10. Therefore, the unmet needs in AAA detection, prevention, and treatment strategies warrant further foundational aneurysm research11.
Animal models that accurately and efficiently recapitulate the features and behaviors of human AAAs are essential for mechanistic studies of aneurysm pathophysiology and identifying potential therapeutic targets. While current animal models can mimic the major aspects of the aneurysmal changes that occur in human disease, no single model fully represents the true complexity of human AAAs. Currently, mice are the most widely accepted species for animal AAA modeling. Researchers should consider the various strengths and weaknesses of each murine model for their particular aneurysm study, such as those expertly described in reviews by Daugherty et al. and Busch et al.12,13.
The use of elastase to induce AAA in rodents was first described by Anidjar et al. in 199014. Perfusing the aorta with porcine pancreatic elastase using a syringe pump creates an initial dilation roughly between 50% and 70%, and the dilated segments favorably demonstrate similar pathologic features of human AAAs, such as medial degeneration and adventitial inflammation. The classic perfusion model, however, is arguably the most technically challenging aneurysm model, and the aneurysms that are typically formed by the second week begin to gradually resolve thereafter. Bhamidipati et al. in 2012 then demonstrated that adventitial application of elastase could also successfully induce similar aneurysms that are more reproducible in size15. A far less challenging model, the topical elastase model became widely adopted in aneurysm research. Additional methodology and advantages of the topical elastase model are discussed in the methods paper by Xue and colleagues16.
The elastase/BAPN model of murine AAA was developed by Lu and colleagues in 20178. Introducing 0.2% BAPN drinking water improved upon many of the critiques of the classic topical elastase model, now producing aneurysms that continually expand to the point of AAA rupture. In their 2017 study, they demonstrated mice in the elastase/BAPN-treated group had significantly higher AAA formation rates compared to the elastase group (93% vs 65%, P &#60; 0.01), which were also more advanced-staged AAAs. Over a 100-day study period, AAAs in the elastase/BAPN group continued to dilate to &#62;800% baseline diameter and formed intraluminal thrombus (53.8%), and 46.2% spontaneously ruptured before the end of the experiment. This model has allowed researchers to investigate factors that may impact aneurysm progression and stability over time.
Berman et al. further explored the elastase/BAPN model by varying the concentration of topical elastase, study duration, timing of BAPN administration, and the impact of animal sex9. Treatment with 5 &#181;L of higher concentrated elastase (5 mg/mL or 10 mg/mL) produced larger aneurysms than 2.5 mg/mL over 56 days. The prevalence of intraluminal thrombus formation also depended on the elastase concentration, which occurred in 28.6% of the 5 mg/mL-treated mice, and 62.5% of the 10 mg/mL-treated mice. They also demonstrated the elastase/BAPN model could induce aneurysms in female mice. Although only a few female mice were studied (n=5), they found the aneurysms in females were more prone to rupture (2 of 5 mice) and were significantly larger than male AAAs at 56 days.
In this paper, we aim to provide a method to address one of the largest limitations of surgical modeling, which is the variation in the surgical procedure. Without a clear consensus on the degree of dissection and the area of the aorta treated with elastase, the results of this model could vary dramatically between animals, investigators, and institutions. We have observed numerous anatomical variations between mice, including the number and size of lumbar arteries and veins, and the location of the IMA, takeoff of the left gonadal vein, among others, which can be limiting when attempting to treat only a portion or specific segment of the infrarenal aorta. Here, we demonstrate that circumferentially dissecting the entire length of the infrarenal aorta from the left renal artery proximally to the aortic bifurcation distally helps to provide reproducible degrees of aortic exposure despite anatomical differences while increasing the success of aneurysm induction and providing clear boundaries for the operator. Additionally, the size and more anterior position of the IVC tends to cover a majority of the aorta, which can affect the amount of aorta treated if not isolated from the IVC. While it is necessary to remove the retroperitoneal fascia to expose the aorta, it is important to not fully dissect the connective tissue of the adventitia off the aorta and expose any of the media layers, as this typically results in rupture during the 5 min elastase incubation period. This could serve as an additional internal control to the degree of the dissection with this model yet can be a frustrating learning curve when adopting this model. Operators will additionally learn higher risk areas (Figure 4) that can be easily injured during surgery and lead to uncontrollable hemorrhage.
While it is important that the procedural steps of this model are consistent, the duration of the study and timing of interval ultrasonography can vary depending on the goal of the research. Aortic dilation begins immediately with elastase application, yet studies using this model commonly follow mice for 28 days post surgery7, as in this example experiment. Extending the study duration should be considered when studying advanced AAAs, long-term growth, intraluminal thrombus formation, or rupture.
Additional perioperative measures, such as maintaining animal body temperature and hydration status can help to improve animal survival of this invasive procedure. The use of a heating pad during surgery and placement in a warm recovery cage can help avoid hypothermia. Saline should be warmed before it is used to irrigate the abdominal cavity. A subcutaneous fluid bolus directly following surgery can account for insensible fluid losses during the operation, and help the animal maintain adequate hydration during the immediate recovery phase. With careful tissue handling and a consistent methodical approach, the elastase/BAPN model can be performed by an experienced operator between 30 min and 45 min per mouse and reliably produce AAA with very low perioperative complications.
Our results demonstrate that the combination of BAPN in addition to circumferential dissection of the infrarenal aorta prior to elastase application produces large, continually expanding AAAs, with larger diameters and rupture incidence at shorter periods. In this experiment, AAAs were successfully induced in all male (6 of 6) and female (6 of 6) mice treated with active elastase. Elastase exposure for 5 min resulted in an immediate increase in aortic diameter by roughly 30-40%, which is helpful in confirming successful and consistent elastase application among treatment groups. Similar to Berman et al., we have shown that this model can induce AAAs in female mice, which also have a greater rupture response than males. Half of the female mice (3 of 6) ruptured within 28 days, compared to 0 of 6 of the males, however, female mice weigh less than males. Male mice demonstrated an increase in AAA diameter by 257% compared to -4% of male controls, while the surviving females showed a 417% diameter increase, compared to -16% of female controls. Aortic diameters were not significantly different between the surviving male and female treated mice at 28 days due to the higher number of ruptures in the female group. We speculate the sham mice exhibit smaller aortic diameters by the end of the study as the aorta tends to dilate slightly during the initial dissection and then, forms scar tissue by 28 days.
The elastase/BAPN model possesses certain limitations. Circumferential dissection of the aorta requires fine surgical skills yet helps improve replicability and the degree of aneurysm induction. Similar to the topical elastase model, there is also a batch effect in elastase enzyme activity, which as mentioned earlier, is therefore important to utilize the same bottle of elastase for all animals in a given experiment. While the incidence of AAA intraluminal thrombus and rupture increases with time and aneurysm severity, these are not guaranteed nor fully predictable in this model.
In summary, the elastase/BAPN model produces large, true infrarenal AAAs in both male and female mice, which progressively expand over time, form intraluminal thrombus, and are capable of rupture. These strengths of this murine model help to better recapitulate some of the behaviors and characteristics of aneurysms in humans. Although technically difficult, careful and thorough dissection of the aorta can augment the aneurysmal response. Currently, the elastase/BAPN method is an advanced model for studying infrarenal abdominal aortic aneurysms.

An aneurysm is defined as a pathologic dilation of a blood vessel greater than 50% of the healthy vessel diameter1. Despite abdominal aortic aneurysms (AAA) being a commonly encountered condition in the aging population, with an incidence of roughly &#62;5% of males &#62; 65 years of age, there are no directed therapeutic strategies for treating AAA1. Current management of AAA is limited to risk factor reduction and surgical repair with either open or endovascular surgery based on aortic diameter or growth rate2. The greatest danger of AAA is aneurysm rupture, which is fatal if untreated, and repair in this emergent setting can carry mortality risks upwards of 90%1.
The pathophysiology of AAA is complicated, multifactorial, and not fully understood3. Features of human AAA include true aneurysmal dilation of the aortic wall with an infiltration of inflammatory cells, the presence of intraluminal thrombus, and progressive dilation that leads to eventual rupture3,4. Additionally, AAAs are associated with advanced age, have a 9:1 male:female sex predominance, and most commonly occur in the infrarenal aorta5. Modeling all features and behaviors of human AAAs in animals remains an ongoing challenge6.
Current AAA modeling is primarily conducted in mice, and aneurysms are commonly induced using one of three methods-by angiotensin II (AngII) infusion via a subcutaneously implanted osmotic pump, and by direct application of calcium chloride (CaCl2) or elastase to the aorta7. In the latter method, porcine pancreatic elastase (PPE) is applied to a segment of the infrarenal aorta and causes enzymatic degradation of elastin fibers within the elastic lamella of the tunica media. This structural damage results in the weakening of the aortic wall and outward aneurysmal dilation. The use of topical elastase alone, however, produces relatively small infrarenal aneurysms, which fail to progressively enlarge or rupture over time. More recently, Lu et al. improved upon this model by additionally administering &#946;-aminopropionitrile (BAPN), an irreversible inhibitor of lysyl oxidase, to their elastase-treated mice8. By preventing the crosslinking of elastin and collagen fibers, BAPN supplementation causes elastase-damaged aortas to progressively dilate to the point of rupture. The elastase/BAPN model additionally has a higher incidence rate of AAA than the topical elastase model, and the aneurysms produced are also larger and contain intraluminal thrombus8.
In the elastase/BAPN model, the degree of surgical dissection and exposure of the aorta to elastase can impact the success and replicability of this model. In this manuscript, we describe that co-administration of BAPN drinking water and topical elastase application to the aorta following circumferential isolation of the entire infrarenal aortic segment improves replicability, accounts for anatomical differences between animals, and results in a greater AAA induction rate, aneurysm sizes and rupture incidence. In this article, we will describe a standardized approach to reliably inducing advanced abdominal aortic aneurysms in mice using a combination of topical elastase- and BAPN-supplemented water.

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advanced abdominal aortic aneurysm modeling in mice by combination of topical elastase and oral &#223;-aminopropionitrile

Advanced Abdominal Aortic Aneurysm Modeling in Mice by Combination of Topical Elastase and Oral &#223;-aminopropionitrile

The topical elastase murine model of abdominal aortic aneurysm (AAA) is enhanced when combined with &#223;-aminopropionitrile (BAPN)-supplemented drinking water to reliably produce true infrarenal aneurysms with behaviors that mimic human AAAs. Topically applying elastase to the adventitia of the infrarenal aorta causes structural damage to the elastic layers of the aortic wall and initiates aneurysmal dilation. Co-administering BAPN, a lysyl oxidase inhibitor, promotes sustained wall degeneration by reducing collagen and elastin crosslinking. This combination results in large AAAs that progressively expand, form intraluminal thrombus, and are capable of rupture. Refining surgical techniques, such as circumferentially isolating the entire infrarenal aortic segment, can help standardize the procedure for a consistent and thorough application of porcine pancreatic elastase despite different operators and anatomic variations between mice. Therefore, the elastase/BAPN model is a refined approach to surgically inducing AAA in mice, which may better recapitulate human aneurysms and provide additional opportunities to study aneurysm growth and rupture risk.

Male and female C57BL/6J mice ages 22-24 weeks were used in this study. Infrarenal aortas were treated with 5 µL of elastase enzyme (6.9 mg protein/mL, 6 units/mg protein) or denatured elastase for 5 min. Elastase-treated male mice demonstrated a 43.4% increase in aortic diameter after 5 min exposure to elastase compared to untreated baseline aortic diameters, while treated female aortas increased by 33.6% (P = 0.0342). Aortic diameters of shams exhibited relatively no change over 5 min exposure to denatured elastase (males 0.5%; females -2.8%). There were no surgically related deaths among the 12 treated and 6 sham mice. Data for the 28-day study is demonstrated in Table 1. Of the female treated mice, 3 of 6 died from AAA rupture; one on postoperative day 20 and two on day 25 (Figure 6). There were no AAA ruptures among treated males. AAAs (defined as an increase &gt;50% of the baseline aorta diameter or death by AAA rupture) were successfully induced in all treated mice (12 of 12). At 28 days, the average AAA diameter of treated males was 2.86 ± 0.31 mm, with an average change percent change of 257 ± 54%, while AAA diameters of the surviving treated female mice were 3.60 ± 1.87 mm, with an average percent change of 417 ± 286% (Figure 7). Sham mice exhibited relatively no change in aortic diameters.
<img alt="Survival analysis graph with B6 mouse cross-section showing day 28 organ development comparison." class="xfigimg" src="/files/ftp_upload/66812/66812fig06.jpg" data-altupdatedat="1788304762000" data-alt="Figure 6"> 
Figure 6: Survival of male and female B6 mice during a 28-day elastase/BAPN model of AAA. (A) AAA rupture occurred in 3 of the 6 treated female mice, (one mouse at 20 days, then two mice at 25 days) while there were no ruptures among the 6 treated male mice at 28 days. (B) Representative images at necropsy of a female mouse that died from AAA rupture. AAA rupture is demonstrated by a large retroperitoneal hematoma (left) and presence of an infrarenal AAA with a wall defect (right). Abbreviations: BAPN = ß-aminopropionitrile; AAA = abdominal aortic aneurysm. <a href="https://www.jove.com/files/ftp_upload/66812/66812fig06large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Aortic diameter results; bar graph and dissected samples; SHAM vs. ELASTASE/BAPN treatment comparison." class="xfigimg" src="/files/ftp_upload/66812/66812fig07.jpg" data-altupdatedat="1788304762000" data-alt="Figure 7"> 
Figure 7: Maximal aortic diameters of elastase/BAPN and sham male and female B6 mice at 28 days. (A) Treated mice exhibit significantly larger infrarenal diameters at 28 days compared to shams. (B) The combination of elastase and BAPN successfully produces large infrarenal AAAs in both male and female B6 mice. Abbreviations: BAPN = ß-aminopropionitrile; AAA = abdominal aortic aneurysm. <a href="https://www.jove.com/files/ftp_upload/66812/66812fig07large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td colspan="3"></td>
			<td>B6 male Sham</td>
			<td>B6 female Sham</td>
			<td>B6 male Elastase/BAPN</td>
			<td>B6 female Elastase/BAPN</td>
		</tr>
		<tr>
			<td colspan="3">Number of mice</td>
			<td>3</td>
			<td>3</td>
			<td>6</td>
			<td>6</td>
		</tr>
		<tr>
			<td colspan="3">Age (weeks)</td>
			<td>22.3 ± 0.0</td>
			<td>22.7 ± 0.7</td>
			<td>23.1 ± 0.2</td>
			<td>23.2 ± 0.2</td>
		</tr>
		<tr>
			<td colspan="3">Weight (g; at surgery)</td>
			<td>36.3 ± 2.5</td>
			<td>23.7 ± 1.2</td>
			<td>32.8 ± 1.7*</td>
			<td>23.7 ± 0.8</td>
		</tr>
		<tr>
			<td colspan="3">Pre-treatment aortic diameter (mm)</td>
			<td>0.89 ± 0.02</td>
			<td>0.75 ± 0.04</td>
			<td>0.81 ± 0.07</td>
			<td>0.73 ± 0.09</td>
		</tr>
		<tr>
			<td colspan="3">Post-treatment aortic diameter (mm)</td>
			<td>0.90 ± 0.03</td>
			<td>0.73 ± 0.01</td>
			<td>1.15 ± 0.03**</td>
			<td>0.98 ± 0.12**</td>
		</tr>
		<tr>
			<td colspan="3">Percent change post 5 min treatment (%)</td>
			<td>0.5 ± 4.4</td>
			<td>-2.8 ± 5.3</td>
			<td>43.4 ± 10.2***</td>
			<td>33.6 ± 4.5***</td>
		</tr>
		<tr>
			<td colspan="3">AAA incidence (%)</td>
			<td>0 / 3</td>
			<td>0 / 3</td>
			<td>6 / 6</td>
			<td>6 / 6</td>
		</tr>
		<tr>
			<td colspan="3">AAA ruptures by 28 days</td>
			<td>0 / 3</td>
			<td>0 / 3</td>
			<td>0 / 6</td>
			<td>3 / 6</td>
		</tr>
		<tr>
			<td colspan="3">Survival to 28 days</td>
			<td>3 / 3</td>
			<td>3 / 3</td>
			<td>6 / 6</td>
			<td>3 / 6</td>
		</tr>
		<tr>
			<td colspan="3">Maximal aortic diameter at 28 days (mm)</td>
			<td>0.85 ± 0.01</td>
			<td>0.64 ± 0.01</td>
			<td>2.86 ± 0.31*</td>
			<td>3.60 ± 1.87**</td>
		</tr>
		<tr>
			<td colspan="3">Percent change aortic diameter at 28 days (%)</td>
			<td>-4 ± 2</td>
			<td>-16 ± 2</td>
			<td>257 ± 54*</td>
			<td>417 ± 286**</td>
		</tr>
	</tbody>
</table>
Table 1: Results of a 28-day model of the elastase/BAPN murine model of AAA. Data are mean ± SD. *P&lt;0.05, **P&lt;0.005, ***P&lt;0.0001 compared to sham of the same sex via one-way ANOVA Fischer's test. Abbreviations: BAPN = ß-aminopropionitrile; AAA = abdominal aortic aneurysm.

This protocol describes a methodical surgical approach to modeling advanced abdominal aortic aneurysms in mice by a combination of directly applying elastase to the infrarenal aorta and administering &#223;-aminopropionitrile through drinking water.

The topical elastase murine model of abdominal aortic aneurysm (AAA) is enhanced when combined with &#223;-aminopropionitrile (BAPN)-supplemented drinking ...

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Research

JoVE Journal

Biology

This video shows how to induce abdominal aortic aneurysms (AAA) in mice via transient intraluminal infusion of porcine pancreatic elastase into the infrarenal segment of the abdominal aorta. The model has the ability to add broad insight into the pathobiology of AAA due to the emergence of numerous transgenic and gene knockout mice.

Creation of Murine Experimental Abdominal Aortic Aneurysms with Elastase 

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.

Murine Surgical Model of Topical Elastase Induced Descending Thoracic 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 β-aminopropionitrile administration, which interferes with collagen cross-linking.

Porcine Model of Infrarenal Abdominal Aortic Aneurysm

The present protocol describes a standardized surgical method for the elastase-induced AAA model through the direct application of elastase to the adventitia of infrarenal abdominal aorta in mice.

Mouse Abdominal Aortic Aneurysm Model Induced by Perivascular Application of Elastase

This manuscript presents a protocol for establishing a mouse abdominal aortic aneurysm model using calcium chloride and elastase, combining the advantages of previous modeling methods. This model can be utilized to investigate the pathophysiological mechanisms underlying abdominal aortic aneurysms.

A Mouse Abdominal Aortic Aneurysm Model by Periadventitial Calcium Chloride and Elastase Infiltration

This protocol provides a repeatable and reliable method for inducing abdominal aortic aneurysms (AAAs) in C57BL/6 mice using elastin sensitization and perivascular elastase application, as an AAA model that incorporates an immune-sensitization component.

Reliable Creation of a Murine Abdominal Aortic Aneurysm Model Using Elastin Sensitization and Perivascular Elastase

Transverse aortic constriction (TAC) in the mouse is a commonly used experimental model to study mechanisms underlying cardiac hypertrophy and heart failure development. Here, we describe procedures to constrict the aorta to create a reproducible degree of cardiac hypertrophy in mice.

Transverse Aortic Constriction in Mice

An efficient genome-wide single gene mutation method has been established using Streptococcus sanguinis as a model organism. This method has achieved via high throughput recombinant PCRs and transformations.

Genome-wide Gene Deletions in Streptococcus sanguinis by High Throughput PCR

Intravital microscopy is a powerful tool that enables imaging various biological processes in live animals. In this article, we present a detailed method for imaging the dynamics of subcellular structures, such as the secretory granules, in the salivary glands of live mice.

Intravital Microscopy for Imaging Subcellular Structures in Live Mice Expressing Fluorescent Proteins

The nature of the interactions between hematopoietic stem and progenitor cells (HSPCs) and bone marrow niches is poorly understood. Custom hardware modifications and a multi-step acquisition protocol allow the use of two-photon and confocal microscopy to image ex vivo labeled HSPCs homed within bone marrow areas, tracking interactions and movement.

In Vivo 4-Dimensional Tracking of Hematopoietic Stem and Progenitor Cells in Adult Mouse Calvarial Bone Marrow

Learn an advanced abdominal aortic aneurysm modeling method using topical elastase and oral BAPN in mice. This technique enables reliable study of aneurysm growth and rupture mechanisms.

Advanced Abdominal Aortic Aneurysm Modeling in Mice by Combination of Topical Elastase and Oral ß-aminopropionitrile

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