Name: patch angioplasty in the rat aorta or inferior vena cava
Uploaded: 2017-02-27T15:00:00.000+00:00
Duration: 6 min 4 s
Description: Watch this Scientific Journal Video about Patch Angioplasty in the Rat Aorta or Inferior Vena Cava at JoVE.com

This work was supported in part by the National Institutes of Health Grants R56-HL095498,&#160;R01-HL-095498 (to AD),&#160;R01-HL128406, the Merit Review Award I01-BX002336 from the United States Department of Veterans Affairs Biomedical Laboratory Research and Development Program (to AD), a Yale Department of Surgery Ohse award (to AD), a Sarnoff Cardiovascular Foundation Fellowship (to JMS), and through the resources and the use of facilities at the Veterans Affairs Connecticut Healthcare System (West Haven, CT). Bovine pericardial patches were generously provided by LeMaitre Vascular Inc. (Burlington, MA).

Approval by the appropriate Institutional Animal Care and Use Committee must be obtained, indicating that your protocol follows the guidelines of your institution&#39;s animal research ethics committee.
1. Anesthesia and Pre-operative Procedures
<ol>
	<li>Anesthetize male Wistar rats, weighing around 200 g, with vaporized 3% isoflurane and 1 L/min oxygen administered into an acrylic induction chamber.</li>
	<li>Confirm adequate anesthesia through a lack of reaction to a toe and tail pinch. Place ointment on the eyes to prevent dryness while the animals are under anesthesia. Position the each rat supine on the plastic operation plate and position a silicone mask to deliver vaporized 2 - 3% isoflurane by continuous inhalation. Do not leave an animal unattended until it has regained sufficient consciousness to maintain sternal recumbency.</li>
	<li>While wearing sterile gloves, remove the ventral abdomen hair using a hair remover. Buprenorphine, either subcutaneously or intraperitoneally, is frequently given at this point.</li>
</ol>
2. Operative Procedures
<ol>
	<li>Patch venoplasty
	<ol>
		<li>Before the surgery, trim the bovine pericardial patch using a microscissor to a 3 mm x 1.5 mm x 0.6 mm size. Soak the patch in 10 mL of sterilized saline for 5 min in a cell culture dish.</li>
		<li>Prepare the incision site with a topical antiseptic according to your institutional protocol and apply a surgical drape. Use sterile gloves and instruments to maintain aseptic technique throughout the surgery. &#160;Local anesthesia can be injected into the site of the planned skin incision.</li>
		<li>Using a scalpel, make a midline abdominal incision extending from the level of the xiphoid to just above the pubis.</li>
		<li>Insert a retractor and eviscerate all bowels from the abdominal cavity towards the right side. Wrap the bowels in gauze soaked with saline.</li>
		<li>Expose the infrarenal vena cava (IVC). The site of patch implantation is approximately 2 mm below the level of the origin of the renal veins; dissect the IVC free at this site. Ligate and divide all lumbar and tributary veins at this level using 6-0 nylon sutures.</li>
		<li>Place two microsurgery clips across both the proximal and distal infarenal IVC. Perform a venotomy with a 25 G needle by puncturing the anterior wall of the IVC, and then extend it to around 3 mm using scissors (Figure 1A).</li>
		<li>Close the venotomy with the patch using running or interrupted 10-0 nylon sutures (Figure 1B).</li>
		<li>Complete the venoplasty closure. Remove the distal clamp first to vent the patch and then remove the proximal clamp to restore blood flow to the IVC.</li>
		<li>Confirm hemostasis by observing for 30 s without compression. Return the bowels to their natural position. Close the abdomen with a running suture according to approved animal protocols.</li>
	</ol>
	</li>
	<li>Patch arterioplasty
	<ol>
		<li>Before the surgery, trim the bovine pericardial patch using a microscissor to a 3 mm x 1.5 mm x 0.6 mm size. Soak it in sterilized saline.</li>
		<li>Prepare the incision site with a topical antiseptic and apply a surgical drape. Use sterile gloves and instruments to maintain aseptic technique throughout the surgery.</li>
		<li>Using a scalpel, make a midline abdominal incision extending from the level of the xiphoid to just above the pubis.</li>
		<li>Insert a retractor and eviscerate all bowels from the abdominal cavity towards the right side. Wrap the bowels in gauze soaked with saline.</li>
		<li>Expose the aorta. The site of patch implantation is approximately 2 mm below the level of the origin of the renal arteries; dissect the aorta free at this site. Ligate and divide all lumbar arteries at this level using 6-0 nylon sutures.</li>
		<li>Clamp the infrarenal aorta. Use a 25 G needle to perform an arteriotomy by puncturing the anterior wall of the aorta, and then extend it to around 3 mm using scissors (Figure 1C).</li>
		<li>Close the arteriotomy with the patch using running 10-0 nylon sutures (Figure 1D). Complete the arterioplasty closure. Remove the distal clamp first to vent the patch and then remove the proximal clamp to restore blood flow to the aorta.</li>
		<li>Confirm hemostasis by observing for 30 s without compression. Return the bowels to their natural position. Close the abdomen with a running suture according to approved animal protocols.</li>
	</ol>
	</li>
</ol>
3. Post-operative Procedures
<ol>
	<li>After the closure of the abdomen, discontinue the anesthesia. Apply post-operative care, including analgesia and wound care, in accordance with instructions recommended by the Institutional Animal Care and Use Committee.</li>
	<li>For analgesia, use buprenorphine at 0.1 mg/kg intramuscularly no less than every 12 h for 24 h following the surgical procedures. Check the status of the animal every day in the animal room, ensuring proper recovery from the peri-operative period as well as adequate treatment of post-surgical pain. Do not return an animal that has undergone surgery to the company of other animals until it has fully recovered.</li>
</ol>
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<ol>
	<li>Muto, A., Nishibe, T., Dardik, H., Dardik, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Patches+for+carotid+artery+endarterectomy:+current+materials+and+prospects.">Patches for carotid artery endarterectomy: current materials and prospects.</a> J Vasc Surg. 50 (1), 206-213 (2009).</li><li>Li, X., 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=Current+usage+and+future+directions+for+the+bovine+pericardial+patch.">Current usage and future directions for the bovine pericardial patch.</a> Ann Vasc Surg. 25 (4), 561-568 (2011).</li><li>Biasi, G. M., Sternjakob, S., Mingazzini, P. M., Ferrari, S. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nine-year+experience+of+bovine+pericardium+patch+angioplasty+during+carotid+endarterectomy.">Nine-year experience of bovine pericardium patch angioplasty during carotid endarterectomy.</a> J Vasc Surg. 36 (2), 271-277 (2002).</li><li>Papakostas, J. 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=Use+of+the+vascu-guard+bovine+pericardium+patch+for+arteriotomy+closure+in+carotid+endarterectomy.+Early+and+long-term+results.">Use of the vascu-guard bovine pericardium patch for arteriotomy closure in carotid endarterectomy. Early and long-term results.</a> Ann Vasc Surg. 28 (5), 1213-1218 (2014).</li><li>Ohwada, 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=Glutaraldehyde-fixed+heterologous+pericardium+for+vena+cava+grafting+following+hepatectomy.">Glutaraldehyde-fixed heterologous pericardium for vena cava grafting following hepatectomy.</a> Hepatogastroenterology. 46 (26), 855-858 (1999).</li><li>Mori, 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=Standard+hepatic+vein+reconstruction+with+patch+plasty+using+the+native+portal+vein+in+adult+living+donor+liver+transplantation.">Standard hepatic vein reconstruction with patch plasty using the native portal vein in adult living donor liver transplantation.</a> Liver Transpl. 18 (5), 602-607 (2012).</li><li>Bai, 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=Pericardial+patch+venoplasty+heals+via+attraction+of+venous+progenitor+cells.">Pericardial patch venoplasty heals via attraction of venous progenitor cells.</a> Physiological Reports. 4 (12), (2016).</li><li>Li, X., 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=Pericardial+patch+angioplasty+heals+via+an+Ephrin-B2+and+CD34+positive+cell+mediated+mechanism.">Pericardial patch angioplasty heals via an Ephrin-B2 and CD34 positive cell mediated mechanism.</a> PLoS One. 7 (6), 38844 (2012).</li><li>Bai, 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=Pretreatment+of+pericardial+patches+with+antibiotics+does+not+alter+patch+healing+in+vivo.">Pretreatment of pericardial patches with antibiotics does not alter patch healing in vivo.</a> J Vasc Surg. 63 (4), 1063-1073 (2016).</li><li>Muto, 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=Eph-B4+prevents+venous+adaptive+remodeling+in+the+adult+arterial+environment.">Eph-B4 prevents venous adaptive remodeling in the adult arterial environment.</a> J Exp Med. 208 (3), 561-575 (2011).</li></ol>

The authors have nothing to disclose.

We describe a patch angioplasty model in the rat that can be used in either veins or arteries, creating a patch venoplasty or patch arterioplasty, respectively. Using this pericardial patch model, we showed aggressive and stable neointimal hyperplasia in the rat IVC venoplasty compared to the aortic arterioplasty (Figure 2)7,8.
Several technical aspects are notable. In the aortic arterioplasty, it is important that the sutures are tight and adequate in number and/or spacing to prevent leakage of blood in the higher pressure of the arterial environment. In the IVC venoplasty, it is important to perform all of the operative maneuvers with particular care and gentleness, as the IVC wall is extremely thin and fragile. In addition, lumbar and small tributary veins around the implantation site must be carefully dissected and ligated to prevent bleeding. In both arterial and venous procedures, the distal clamp is removed first to vent any luminal air and to avoid a pulmonary air embolism. The proximal clamp is then removed to restore the distal blood flow.&#160;Lastly, when puncturing the aorta or IVC wall, do not puncture the posterior wall; if the posterior wall is punctured, a 10-0 suture should be used to close the hole.
A disadvantage of the patch angioplasty in the aorta is the development of pseudoaneurysms at later times (e.g., post-operative day 30). However, there were rarely any pseudoaneurysms observed on post-operative days 7 or 14, suggesting the utility of this model during the first 2 weeks after the procedure to study neointimal formation in either the venous or the arterial environment7,9.
Small-animal patch angioplasty has several advantages compared to interposition graft models. First, the host vessel does not need to be transected, as only an anterior wall incision is made; this reduces surgical time and minimizes the risk of bleeding. Second, the interposition graft requires two anastomoses, increasing the operative time and risk for complications, as well as extending the learning curve. Patch angioplasty requires only a single anastomosis, reducing the operative time and the risk of complications. Third, patch angioplasty intrinsically reduces the risk of stenosis at the anastomotic site, potentially allowing an increased time for postoperative observation10.
In conclusion, we describe a method to perform patch angioplasty that uses pericardial patches to close small-diameter vessels; the procedure is equally applicable to both veins and arteries. Pericardial patch venoplasty shows more aggressive neointimal formation compared to the arterioplasty model at early postoperative times. This result suggests the utility of this model in determining the differences in interactions between the venous and the arterial environments with implantable biomaterials. In addition, different types of patch compositions can be examined to test the response to these different materials.

Vascular surgeons commonly close blood vessels with pericardial patches, either bovine or porcine, to reduce the risk of restenosis1,2. In arterial surgery, pericardial patch angioplasty reduces the rate of restenosis compared to a primary closure3,4. Patch venoplasty is also similarly performed to close veins, although less frequently when compared to arterial procedures5,6. Patches typically develop neointimal hyperplasia on their luminal surfaces; however, the mechanism of neointimal formation remains unclear, especially in the comparison of differences in neointimal formation between the arterial and venous environments. We previously showed that pericardial patches attract progenitor cells in both the arterial and the venous environments and that venous patch angioplasty shows more aggressive neointimal formation as compared to the arterial patches7,8.
In this study, we describe the rat model of pericardial patch angioplasty that is common to closing both veins and arteries and that may be used to study neointimal formation; this method is a small-animal model of an operative technique commonly used in human patients. The rat model has a larger diameter than the mouse model, facilitating technical aspects of the surgery and improving the learning curve for the model.

<table><tbody><tr><td>Bovine pericardial patch</td><td>LeMaitre Vascular</td><td></td><td></td></tr><tr><td>Vascular clamp</td><td>Roboz Surgical Instrument Co.</td><td>RS-5424</td><td></td></tr><tr><td>Clamp applying forceps</td><td>Roboz Surgical Instrument Co</td><td>RS-5410</td><td></td></tr><tr><td>10-0 Prolene suture</td><td>Arosurgical Co.</td><td>T05A10N10-13</td><td></td></tr></tbody></table>

patch angioplasty in the rat aorta or inferior vena cava

Pericardial patches are commonly used in vascular surgery to close vessels. To facilitate studies of the neointimal hyperplasia that forms on the patch, we developed a rat model of patch angioplasty that can be used in either a vein or an artery, creating a patch venoplasty or a patch arterioplasty, respectively. Technical aspects of this model are discussed. The infra-renal IVC or aorta are dissected and then clamped proximally and distally. A 3 mm venotomy or arteriotomy is performed in the infrarenal inferior vena cava or aorta of 6 to 8 week-old Wistar rats. A bovine pericardial patch (3 mm x 1.5 mm x 0.6 mm) is then used to close the site using a 10-0 nylon suture. Compared to arterial patches, venous patches show increased neointimal thickness on postoperative day 7. This novel model of pericardial patch angioplasty can be used to examine neointimal hyperplasia on vascular biomaterials, as well as to compare the differences between the arterial and venous environments.

After the patch angioplasty, there was no thrombosis in either the venous (n = 42) or arterial (n = 24) patch groups. Survival at day 7 was 100% in both groups with either a venous or arterial patch.
The patches were harvested on day 7 and stained with hematoxylin and eosin, and the neointimal thickness was compared as previously described7. Because of the distinct morphological difference between the patch and the neointima, it is very easy to discriminate the neointima. In the venous patch, there was a distinct layer of thick neointima on the luminal side of the patch, with more cells accumulated in the neointima (Figure 2A, 2C); in the arterial patch, there was a much thinner neointimal layer, with only a few cells attached to the luminal side of the patch (Figure 2B, 2D). The neointima was significantly thicker in the venous patch compared to the artery patch (Figure 2E). Similar results were obtained on day 14 (data not shown). These results show that the patch venoplasty model is superior over other models to acquire a thick neointima in a short period of time.
<img alt="Figure 1" src="/files/ftp_upload/55253/55253fig1.jpg" /> 
Figure 1: Rat Pericardial Patch Angioplasty. (A) Representative photograph showing the IVC venotomy. (B) Representative photograph showing the IVC after patch placement. (C) Representative photograph showing the aortic arteriotomy. (D) Representative photograph showing the aorta after patch placement. A, aorta; IVC, inferior vena cava; P, pericardial patch; *, posterior intima of IVC or aorta; ruler markings are 1 mm. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55253/55253fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" src="/files/ftp_upload/55253/55253fig2.jpg" /> 
Figure 2: Aggressive Neointimal Hyperplasia in Patch Venoplasty Compared to Patch Arterioplasty at Day 7. 
(A) Representative lower-power photograph showing the patch venoplasty on day 7, which was stained with H&#38;E. (B) Representative lower-power photograph showing the patch angioplasty at day 7, which was stained with H&#38;E. (C) Representative high-power photograph showing the neointimal formation on the patch venoplasty. (D) Representative high-power photograph showing the neointimal formation on the patch arterioplasty. Scale bar = 0.5 mm; high power = 100 &#181;m. P, patch; L, IVC or aorta lumen; N, neointima. (E) Bar graph showing increased neointimal thickness in the venoplasty compared to arterioplasty. The error bar denotes the SEM; *P = 0.0015, t-test; n = 4. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55253/55253fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about Patch Angioplasty in the Rat Aorta or Inferior Vena Cava at JoVE.com

Patch Angioplasty in the Rat Aorta or Inferior Vena Cava

We have established a model of pericardial patch angioplasty that can be used in either small-diameter veins or arteries. This model can be used to compare venous and arterial neointimal hyperplasia formation.

Pericardial patches are commonly used in vascular surgery to close vessels. To facilitate studies of the neointimal hyperplasia that forms on the patch, ...

patch-angioplasty-in-the-rat-aorta-or-inferior-vena-cava

Nanyang Technological University

Research

JoVE Journal

Medicine

10.5K Views.  Yale University. We have established a model of pericardial patch angioplasty that can be used in either small-diameter veins or arteries. This model can be used to compare venous and arterial neointimal hyperplasia formation.

Video: Patch Angioplasty in the Rat Aorta or Inferior Vena Cava

Orthotopic Aortic Transplantation: A Rat Model to Study the Development of Chronic Vasculopathy

Research models of chronic rejection are essential to investigate pathobiological and pathophysiological processes during the development of transplant vasculopathy (TVP).
The commonly used animal model for cardiovascular chronic rejection studies is the heterotopic heart transplant model performed in laboratory rodents. This model is used widely in experiments since Ono and Lindsey (3) published their technique. To analyze the findings in the blood vessels, the heart has to be sectioned and all vessels have to be measured.
Another method to investigate chronic rejection in cardiovascular questionings is the aortic transplant model (1, 2). In the orthotopic aortic transplant model, the aorta can easily be histologically evaluated (2). The PVG-to-ACI model is especially useful for CAV studies, since acute vascular rejection is not a major confounding factor and Cyclosporin A (CsA) treatment does not prevent the development of CAV, similar to what we find in the clinical setting (4). A7-day period of CsA is required in this model to prevent acute rejection and to achieve long-term survival with the development of TVP.
This model can also be used to investigate acute cellular rejection and media necrosis in xenogeneic models (5).

This video demonstrates the orthotopic aortic transplant model as a simple model to study the development of transplant vasculopathy (TVP) in rats.

Research models of chronic rejection are essential to investigate pathobiological and pathophysiological processes during the development of transplant ...

Angiogenesis in the Ischemic Rat Lung

The adult lung is perfused by both the systemic bronchial artery and the entire venous return flowing through the pulmonary arteries. In most lung pathologies, it is the smaller systemic vasculature that responds to a need for enhanced lung perfusion and shows robust neovascularization. Pulmonary vascular ischemia induced by pulmonary artery obstruction has been shown to result in rapid systemic arterial angiogenesis in man as well as in several animal models. Although the histologic assessment of the time course of bronchial artery proliferation in rats was carefully described by Weibel 1, mechanisms responsible for this organized growth of new vessels are not clear. We provide surgical details of inducing left pulmonary artery ischemia in the rat that leads to bronchial neovascularization. Quantification of the extent of angiogenesis presents an additional challenge due to the presence of the two vascular beds within the lung. Methods to determine functional angiogenesis based on labeled microsphere injections are provided.

The lung is perfused by both the systemic bronchial artery and pulmonary arteries. In most lung pathologies, it is the smaller systemic vasculature that shows robust neovascularization. Cessation of pulmonary blood flow promotes brisk bronchial angiogenesis. We provide surgical details of inducing left pulmonary artery ischemia that promotes bronchial neovascularization.

The  adult lung is perfused by both the systemic bronchial artery and the entire  venous return flowing through the pulmonary arteries. In most lung ...

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 ...

Imaging In-Stent Restenosis: An Inexpensive, Reliable, and Rapid Preclinical Model

Preclinical models of restenosis are essential to unravel the pathophysiological processes that lead to in-stent restenosis and to optimize existing and future drug-eluting stents.
A variety of antibodies and transgenic and knockout strains are available in rats. Consequently, a model for in-stent restenosis in the rat would be convenient for pathobiological and pathophysiological studies. 
In this video, we present the full procedure and pit-falls of a rat stent model suitable for high throughput stent research. We will show the surgical procedure of stent deployment, and the assessment of in-stent restenosis using the most elegant technique of OCT (Optical Coherence Tomography). This technique provides high accuracy in assessing plaque CSAs (cross section areas) and correlates well with histological sections, which require special and time consuming embedding and sectioning techniques. OCT imaging further allows longitudinal monitoring of the development of in-stent restenosis within the same animal compared to one-time snapshots using histology.

This video demonstrates how to use a preclinical inexpensive and reliable model to study pathobiological and pathophysiological processes of in-stent restenosis development. Longitudinal in vivo monitoring using OCT (Optical Coherence Tomography) and analysis of OCT images are also demonstrated.

Preclinical models of restenosis are essential to unravel the pathophysiological processes that lead to in-stent restenosis and to optimize existing and ...

Biology

Vascular Balloon Injury and Intraluminal Administration in Rat Carotid Artery

The carotid artery balloon injury model in rats has been well established for over two decades. It remains an important method to study the molecular and cellular mechanisms involved in vascular smooth muscle dedifferentiation, neointima formation and vascular remodeling. Male Sprague-Dawley rats are the most frequently employed animals for this model. Female rats are not preferred as female hormones are protective against vascular diseases and thus introduce a variation into this procedure. The left carotid is typically injured with the right carotid serving as a negative control. Left carotid injury is caused by the inflated balloon that denudes the endothelium and distends the vessel wall. Following injury, potential therapeutic strategies such as the use of pharmacological compounds and either gene or shRNA transfer can be evaluated. Typically for gene or shRNA transfer, the injured section of the vessel lumen is locally transduced for 30 min with viral particles encoding either a protein or shRNA for delivery and expression in the injured vessel wall. Neointimal thickening representing proliferative vascular smooth muscle cells usually peaks at 2 weeks after injury. Vessels are mostly harvested at this time point for cellular and molecular analysis of cell signaling pathways as well as gene and protein expression. Vessels can also be harvested at earlier time points to determine the onset of expression and/or activation of a specific protein or pathway, depending on the experimental aims intended. Vessels can be characterized and evaluated using histological staining, immunohistochemistry, protein/mRNA assays, and activity assays. The intact right carotid artery from the same animal is an ideal internal control. Injury-induced changes in molecular and cellular parameters can be evaluated by comparing the injured artery to the internal right control artery. Likewise, therapeutic modalities can be evaluated by comparing the injured and treated artery to the control injured only artery.

This protocol uses a balloon catheter to cause an intraluminal injury on the rat carotid artery and henceforth elicit neointimal hyperplasia. This is a well-established model for studying the mechanisms of vascular remodeling in response to injury. It is also widely used to determine the validity of potential therapeutic approaches.

The carotid artery balloon injury model in rats has been well established for over two decades. It remains an important method to study the molecular and ...

A Rat Carotid Balloon Injury Model to Test Anti-vascular Remodeling Therapeutics

The rat carotid balloon injury is a well-established surgical model that has been used to study arterial remodeling and vascular cell proliferation. It is also a valuable model system to test, and to evaluate therapeutics and drugs that negate maladaptive remodeling in the vessel. The injury, or barotrauma, in the vessel lumen caused by an inflated balloon via an inserted catheter induces subsequent neointimal growth, often leading to hyperplasia or thickening of the vessel wall that narrows, or obstructs the lumen. The method described here is sufficiently sensitive, and the results can be obtained in relatively short time (2 weeks after the surgery). The efficacy of the drug or therapeutic against the induced-remodeling can be evaluated either by the post-mortem pathological and histomorphological analysis, or by ultrasound sonography in live animals. In addition, this model system has also been used to determine the therapeutic window or the time course of the administered drug. These studies can leadto the development of a better administrative strategy and a better therapeutic outcome. The procedure described here provides a tool for translational studies that bring drug and therapeutic candidates from bench research to clinical applications.

The rat carotid balloon injury model described below allows researchers to evaluate drugs or therapeutics that negate injury-induced arterial hyperplasia. Detailed pre-surgical preparation, surgical procedure, and post-surgical cares of the animal are described.

The rat carotid balloon injury is a well-established surgical model that has been used to study arterial remodeling and vascular cell proliferation. It is ...

Shunt Surgery, Right Heart Catheterization, and Vascular Morphometry in a Rat Model for Flow-induced Pulmonary Arterial Hypertension

In this protocol, PAH is induced by combining a 60 mg/kg monocrotalin (MCT) injection with increased pulmonary blood flow through an aorto-caval shunt (MCT+Flow). The shunt is created by inserting an 18-G needle from the abdominal aorta into the adjacent caval vein. Increased pulmonary flow has been demonstrated as an essential trigger for a severe form of PAH with distinct phases of disease progression, characterized by early medial hypertrophy followed by neointimal lesions and the progressive occlusion of the small pulmonary vessels. To measure the right heart and pulmonary hemodynamics in this model, right heart catheterization is performed by inserting a rigid cannula containing a flexible ball-tip catheter via the right jugular vein into the right ventricle. The catheter is then advanced into the main and the more distal pulmonary arteries. The histopathology of the pulmonary vasculature is assessed qualitatively, by scoring the pre- and intra-acinar vessels on the degree of muscularization and the presence of a neointima, and quantitatively, by measuring the wall thickness, the wall-lumen ratios, and the occlusion score.

This protocol describes a surgical procedure to create a model for flow-induced pulmonary arterial hypertension (PAH) in rats and the procedures to analyze the principle hemodynamic and histological end-points in this model.

In this protocol, PAH is induced by combining a 60 mg/kg monocrotalin (MCT) injection with increased pulmonary blood flow through an aorto-caval shunt ...

Biodegradable Magnesium Stent Treatment of Saccular Aneurysms in a Rat Model - Introduction of the Surgical Technique

The steady progess in the armamentarium of techniques available for endovascular treatment of intracranial aneurysms requires affordable and reproducable experimental animal models to test novel embolization materials such as stents and flow diverters. The aim of the present project was to design a safe, fast, and standardized surgical technique for stent assisted embolization of saccular aneurysms in a rat animal model.
Saccular aneurysms were created from an arterial graft from the descending aorta.The aneurysms were microsurgically transplanted through end-to-side anastomosis to the infrarenal abdominal aorta of a syngenic male Wistar rat weighing &#62;500 g. Following aneurysm anastomosis, aneurysm embolization was performed using balloon expandable magnesium stents (2.5 mm x 6 mm). The stent system was retrograde introduced from the lower abdominal aorta using a modified Seldinger technique.
Following a pilot series of 6 animals, a total of 67 rats were operated according to established standard operating procedures. Mean surgery time, mean anastomosis time, and mean suturing time of the artery puncture site were 167 &#177; 22 min, 26 &#177; 6 min and 11 &#177; 5 min, respectively. The mortality rate was 6% (n=4). The morbidity rate was 7.5% (n=5), and in-stent thrombosis was found in 4 cases (n=2 early, n=2 late in stent thrombosis).
The results demonstrate the feasibility of standardized stent occlusion of saccular sidewall aneurysms in rats - with low rates of morbidity and mortality. This stent embolization procedure combines the opportunity to study novel concepts of stent or flow diverter based devices as well as the molecular aspects of healing.

Reproducable experimental animal models are needed for the testing of novel embolization materials, which have been designed to treat endovascular occlusion of intracranial aneurysms (IA). The present study aims to develop a safe and standardized surgical technique for stent assisted embolization of saccular aneurysms in a rat animal model.

The steady progess in the armamentarium of techniques available for endovascular treatment of intracranial aneurysms requires affordable and reproducable ...

Neuroscience

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 ...

A Rat Carotid Artery Pressure-Controlled Segmental Balloon Injury with Periadventitial Therapeutic Application

Cardiovascular disease remains the leading cause of death and disability worldwide, in part due to atherosclerosis. Atherosclerotic plaque narrows the luminal surface area in arteries thereby reducing adequate blood flow to organs and distal tissues. Clinically, revascularization procedures such as balloon angioplasty with or without stent placement aim to restore blood flow. Although these procedures reestablish blood flow by reducing plaque burden, they damage the vessel wall, which initiates the arterial healing response. The prolonged healing response causes arterial restenosis, or re-narrowing, ultimately limiting the long-term success of these revascularization procedures. Therefore, preclinical animal models are integral for analyzing the pathophysiological mechanisms driving restenosis, and provide the opportunity to test novel therapeutic strategies. Murine models are cheaper and easier to operate on than large animal models. Balloon or wire injury are the two commonly accepted injury modalities used in murine models. Balloon injury models in particular mimic the clinical angioplasty procedure and cause adequate damage to the artery for the development of restenosis. Herein we describe the surgical details for performing and histologically analyzing the modified, pressure-controlled rat carotid artery balloon injury model. Additionally, this protocol highlights how local periadventitial application of therapeutics can be used to inhibit neointimal hyperplasia. Lastly, we present light sheet fluorescence microscopy as a novel approach for imaging and visualizing the arterial injury in three-dimensions.

The rat carotid artery balloon injury mimics the clinical angioplasty procedure performed to restore blood flow in atherosclerotic vessels. This model induces the arterial injury response by distending the arterial wall, and denuding the intimal layer of endothelial cells, ultimately causing remodeling and an intimal hyperplastic response.

Cardiovascular disease remains the leading cause of death and disability worldwide, in part due to atherosclerosis. Atherosclerotic plaque narrows the ...

Patch Angioplasty in the Rat Aorta or Inferior Vena Cava

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