This work was supported by US National Institute of Health (NIH) Grant R01-HL128406; the United States Department of Veterans Affairs Biomedical Laboratory Research and Development Program Merit Review Award I01-BX002336; as well as with the resources and the use of facilities at the VA Connecticut Healthcare System, West Haven, CT.

All experiments were performed with approval from the Yale University Institutional Animal Care and Use Committee (IACUC).
1. Anesthesia and pre-operative procedures
<ol>
	<li>Sterilize all surgical instruments and materials by autoclaving. Turn on the thermal support device to be certain it is warm (40&#8211;42 &#176;C).</li>
	<li>Place a 9&#8211;11-week old C57BL/6 mouse into an acrylic induction chamber and anesthetize it with vaporized 2.5% isoflurane and 0.8 L/min oxygen. Anesthesia induction takes about 3 min.</li>
	<li>Remove the mouse from the chamber. Confirm a deep plane of anesthesia by a toe pinch, an ear pinch and a tail pinch. Place the mouse in supine position on the surgical area and deliver 2.5% isoflurane using silicone mask. Provide buprenorphine at 0.1 mg/kg analgesic and apply ophthalmic ointment to the eyes.</li>
	<li>Remove fur from the ventral side of the neck to the lower abdomen using Nair, a hair remover.</li>
	<li>Cleanse and disinfect the surgical site by using a two-step scrub with 10% povidone-iodine and 70% isopropanol. Apply a surgical drape.</li>
</ol>
2. Operative procedures
<ol>
	<li>Exposure of the clamp and puncture sites
	<ol>
		<li>Prepare sterile instruments and wear sterile gloves to maintain sterility throughout the surgery.</li>
		<li>Make a skin-deep midline abdominal incision with a scalpel from the level of the lower liver edge to just above the pubis. Cut through the musculature with scissors to open the abdominal cavity.</li>
		<li>Insert a retractor into the abdomen and pull out the bowels to the right side. Keep them moist by wrapping in a saline-soaked gauze. Retreive the bladder and the seminal vesicles (in male mice) and pull them out to the caudal side. Dissect the mesentery between the rectum and retroperitoneum with a micro-needle holder to obtain a full view of the aorta and IVC.</li>
		<li>Dissect the infra-renal aorta and IVC en bloc from the lateral and dorsal surrounding retroperitoneal tissues with a micro-needle holder to cross-clamp them together.</li>
		<li>Dissect the surrounding tissues to expose the aortic puncture site at approximately three-quarters of the distance from the left renal vein to the aortic bifurcation.</li>
	</ol>
	</li>
	<li>IVC dissection
	<ol>
		<li>Dissect between the infra-renal IVC and aorta immediately distal to the left renal vein. Extend the dissection distally to the halfway between the left renal vein and the aortic bifurcation, so that the infra-renal IVC, both upstream and downstream to the stenosis, can be observed postoperatively. 
		NOTE: Blunt dissection between the IVC and aorta should be performed from immediately distal to the left renal vein where the connective tissue between the IVC and the aorta is relatively loose.</li>
		<li>Make a window to separate the IVC from the aorta at that level and dissect the IVC from the surrounding tissue. Place an 8-0 polyamide monofilament suture firstly beneath the IVC and aorta (Figure 1A), then position the suture beneath only the IVC (Figure 1B) by pulling the suture end through the window. 
		NOTE: Since the IVC is fragile, dissecting along the aortic adventitia is useful to make a window to prevent the IVC as well as small IVC or aortic branches from being damaged. If bleeding occurs, it is likely to be uncontrollable. If the IVC has distinct side branches, place an 8-0 suture distally to the branches.</li>
	</ol>
	</li>
	<li>AVF creation
	<ol>
		<li>Bend a 25 G needle to a 45&#8211;60&#176; angle at a point ~4 mm from the needle tip.</li>
		<li>Clamp the infra-renal aorta and IVC by applying a microsurgical clip.</li>
		<li>Rotate the aorta medially and caudally by grasping the connective tissue surrounding the bifurcation to expose the puncture site of the aorta stretched it slightly to the ventral side.</li>
		<li>Holding the aorta in a suitable position, puncture through the aorta into the IVC using the prepared 25 G needle (Figure 1C).</li>
		<li>Release the aorta and cover the puncture site with the surrounding tissue pulling up from the left side of the aorta. Take out the needle and press the puncture site gently using a cotton-tipped swab for hemostasis.</li>
	</ol>
	</li>
	<li>Creation of the IVC stenosis 
	<ol>
		<li>Place a tip of a 22 G IV catheter (see the Table of Materials) onto the IVC longitudinally. Ligate the IV catheter and IVC together with an 8-0 suture (Figure 1D), and then remove the IV catheter.</li>
		<li>Confirm primary hemostasis (Figure 1E) and then unclamp the aorta and IVC. Cover the puncture site 1 min more to ensure hemostasis. 
		NOTE: Do not clamp for too long so as to avoid IVC thrombosis distal to the stenosis.</li>
		<li>Return organs to their original positions and close the abdomen with 6-0 sutures.</li>
	</ol>
	</li>
</ol>
3. Post-operative procedures
<ol>
	<li>After closure of the abdominal wound, discontinue isoflurane inhalation. Put the mouse into an individual bedding-free cage and place the cage on a thermal support device to prevent hypothermia. 
	NOTE: The mouse is observed until they achieve and maintain sternal recumbency. Apply post-operative care including analgesia and wound care in accordance with recommendations of the local IACUC. For analgesia we use buprenorphine at 0.1 mg/kg intrasmuscularly every 12 h for 48&#160;h following the surgical procedures and thereafter as needed.</li>
	<li>Confirm the AVF patency postoperatively by using Doppler ultrasound (see the Table of Materials). In addition, measure other vessel and flow characteristics as required.</li>
</ol>

<ol>
	<li>Dember, L. 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=Effect+of+clopidogrel+on+early+failure+of+arteriovenous+fistulas+for+hemodialysis:+a+randomized+controlled+trial.">Effect of clopidogrel on early failure of arteriovenous fistulas for hemodialysis: a randomized controlled trial.</a> JAMA. 299 (18), 2164-2171 (2008).</li><li>Dixon, B. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Why+don't+fistulas+mature?.">Why don't fistulas mature?.</a> Kidney International. 70 (8), 1413-1422 (2006).</li><li>Wilmink, T., Hollingworth, L., Powers, S., Allen, C., Dasgupta, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Natural+History+of+Common+Autologous+Arteriovenous+Fistulae:+Consequences+for+Planning+of+Dialysis.">Natural History of Common Autologous Arteriovenous Fistulae: Consequences for Planning of Dialysis.</a> European Journal of Vascular and Endovascular Surgery. 51 (1), 134-140 (2016).</li><li>Al-Jaishi, A. 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=Patency+rates+of+the+arteriovenous+fistula+for+hemodialysis:+a+systematic+review+and+meta-analysis.">Patency rates of the arteriovenous fistula for hemodialysis: a systematic review and meta-analysis.</a> American Journal of Kidney Diseases. 63 (3), 464-478 (2014).</li><li>Rocco, M. V., Bleyer, A. J., Burkart, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Utilization+of+inpatient+and+outpatient+resources+for+the+management+of+hemodialysis+access+complications.">Utilization of inpatient and outpatient resources for the management of hemodialysis access complications.</a> American Journal of Kidney Diseases. 28 (2), 250-256 (1996).</li><li>Roy-Chaudhury, P., Sukhatme, V. P., Cheung, A. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hemodialysis+vascular+access+dysfunction:+a+cellular+and+molecular+viewpoint.">Hemodialysis vascular access dysfunction: a cellular and molecular viewpoint.</a> Journal of the American Society of Nephrology. 17 (4), 1112-1127 (2006).</li><li>Quencer, K. B., Arici, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Arteriovenous+Fistulas+and+Their+Characteristic+Sites+of+Stenosis.">Arteriovenous Fistulas and Their Characteristic Sites of Stenosis.</a> AJR: American Journal of Roentgenology. 205 (4), 726-734 (2015).</li><li>Kian, K., Asif, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cephalic+arch+stenosis.">Cephalic arch stenosis.</a> Semin Dial. 21 (1), 78-82 (2008).</li><li>Agarwal, A. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Central+vein+stenosis.">Central vein stenosis.</a> American Journal of Kidney Diseases. 61 (6), 1001-1015 (2013).</li><li>Glanz, 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=Axillary+and+subclavian+vein+stenosis:+percutaneous+angioplasty.">Axillary and subclavian vein stenosis: percutaneous angioplasty.</a> Radiology. 168 (2), 371-373 (1988).</li><li>Yamamoto, K., 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+mouse+aortocaval+fistula+recapitulates+human+arteriovenous+fistula+maturation.">The mouse aortocaval fistula recapitulates human arteriovenous fistula maturation.</a> American Journal of Physiology: Heart and Circulatory Physiology. 305 (12), H1718-H1725 (2013).</li><li>North American Symptomatic Carotid Endarterectomy Trial. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Methods,+patient+characteristics,+and+progress.">Methods, patient characteristics, and progress.</a> Stroke. 22 (6), 711-720 (1991).</li><li>Kuwahara, 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=CD44+Promotes+Inflammation+and+Extracellular+Matrix+Production+During+Arteriovenous+Fistula+Maturation.">CD44 Promotes Inflammation and Extracellular Matrix Production During Arteriovenous Fistula Maturation.</a> Arteriosclerosis, Thrombosis, and Vascular Biology. 37 (6), 1147-1156 (2017).</li><li>Protack, C. D., 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+regulates+adaptive+venous+remodeling+to+improve+arteriovenous+fistula+patency.">Eph-B4 regulates adaptive venous remodeling to improve arteriovenous fistula patency.</a> Scientific Reports. 7 (1), 15386 (2017).</li><li>Payne, H., Brill, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stenosis+of+the+Inferior+Vena+Cava:+A+Murine+Model+of+Deep+Vein+Thrombosis.">Stenosis of the Inferior Vena Cava: A Murine Model of Deep Vein Thrombosis.</a> J Vis Exp. (130), (2017).</li><li>Nam, D., 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=Partial+carotid+ligation+is+a+model+of+acutely+induced+disturbed+flow,+leading+to+rapid+endothelial+dysfunction+and+atherosclerosis.">Partial carotid ligation is a model of acutely induced disturbed flow, leading to rapid endothelial dysfunction and atherosclerosis.</a> American Journal of Physiology: Heart and Circulatory Physiology. 297 (4), H1535-H1543 (2009).</li><li>Ene-Iordache, B., Remuzzi, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Disturbed+flow+in+radial-cephalic+arteriovenous+fistulae+for+haemodialysis:+low+and+oscillating+shear+stress+locates+the+sites+of+stenosis.">Disturbed flow in radial-cephalic arteriovenous fistulae for haemodialysis: low and oscillating shear stress locates the sites of stenosis.</a> Nephrology, Dialysis, Transplantation. 27 (1), 358-368 (2012).</li><li>Yamamoto, K., 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=Disturbed+shear+stress+reduces+Klf2+expression+in+arterial-venous+fistulae+in+vivo.">Disturbed shear stress reduces Klf2 expression in arterial-venous fistulae in vivo.</a> Physiological reports. 3, (2015).</li><li>Remuzzi, A., Ene-Iordache, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Novel+paradigms+for+dialysis+vascular+access:+upstream+hemodynamics+and+vascular+remodeling+in+dialysis+access+stenosis.">Novel paradigms for dialysis vascular access: upstream hemodynamics and vascular remodeling in dialysis access stenosis.</a> Clinical Journal of the American Society of Nephrology. 8 (12), 2186-2193 (2013).</li></ol>

The authors have nothing to disclose.

The murine AVF model has been used to study the basic mechanisms and molecular events leading to AVF maturation13,14. In this study, we modified an established murine AVF model to create a novel murine aortocaval fistula model with an IVC stenosis in the outflow tract of the fistula. Our ligation model is similar to several previously described murine models that use vascular ligation. A murine model of deep vein thrombosis was created using partial IVC ligation ...

Arteriovenous fistulae (AVF) are the most common accesses for hemodialysis, with superior patency and reduced infection compared to other accesses such as grafts or central venous catheters. However, up to 60% of AVF fail to mature1,2,3; a recent systematic review reported that primary patency rates at 1 year were only 60%4. Stenosis along the venous outflow predominantly causes failure of AVF maturation5,6. There are certain characteristic locations prone to stenosis proximal to the fistula: the juxtaanastomotic swing segment for the radiocephalic fistula, the cephalic arch region for the brachiocephalic fistula and the central vein for the fistula with previously placed ipsilateral subclavian or internal jugular vein catheters7,8.
Central venous stenosis is often asymptomatic in patients without an AVF, but can cause ipsilateral extremity edema by venous hypertension as well as failure of fistula maturation when challenged by fistula flow9. The pathophysiology of central venous stenosis is most likely related to inflammation and the activated coagulation cascade after device placement. Furthermore, constant movement of the catheter tip as well as increased flow from the fistula can alter shear stress, resulting in platelet deposition and venous wall thickening10. To understand the basic mechanisms underlying AVF failure caused by central venous stenosis, an animal model mimicking central venous stenosis with an AVF is required.
We have established a murine aortocaval fistula model that is easy to perform and master and recapitulates the clinical course of human AVF.11 We applied the concepts and technique of several previously established murine models to create a novel murine AVF model with venous stenosis. We introduce a murine aortocaval fistula model with an IVC stenosis in the outflow fistula that can be used for the study of central venous stenosis.

<table>
	<tbody>
		<tr>
			<td>20-60 Mhz scan head</td>
			<td>VisualSonics Inc.</td>
			<td>RMV-704</td>
			<td></td>
		</tr>
		<tr>
			<td>8-0 Sterile Micro Suture, 6mm (140 &#181;), 3/8 Circle, TAP Point Needle</td>
			<td>AROSuture</td>
			<td>T06A08N14-13</td>
			<td>polyamide monofilament sutures</td>
		</tr>
		<tr>
			<td>Induction Chamber, 2 Liter 
			3.75&#34;W x 9.00&#34;D x 3.75&#34;H</td>
			<td>VetEquip</td>
			<td>941444</td>
			<td></td>
		</tr>
		<tr>
			<td>Isoflo, Isoflurane liquid</td>
			<td>Zoetis</td>
			<td>26675-46-7</td>
			<td></td>
		</tr>
		<tr>
			<td>Mice, C57BL/6J</td>
			<td>The Jackson Laboratory</td>
			<td>664</td>
			<td></td>
		</tr>
		<tr>
			<td>Pet Bed Microwave Heating Pad</td>
			<td>Snuggle Safe</td>
			<td>6250</td>
			<td></td>
		</tr>
		<tr>
			<td>PrecisionGlide Needle 25G</td>
			<td>BD</td>
			<td>305122</td>
			<td></td>
		</tr>
		<tr>
			<td>Surflo I.V. Catheter 22G</td>
			<td>Terumo</td>
			<td>SR-OX2225CA</td>
			<td>0.85mm outer diameter</td>
		</tr>
		<tr>
			<td>Vascular clamp</td>
			<td>Roboz Surgical Instrument</td>
			<td>RS-5424</td>
			<td></td>
		</tr>
		<tr>
			<td>Vevo770 High Resolution Imaging System</td>
			<td>VisualSonics Inc.</td>
			<td>770</td>
			<td></td>
		</tr>
	</tbody>
</table>

murine model of central venous stenosis using aortocaval fistula with an outflow stenosis

Central venous stenosis is an important entity contributing to arteriovenous fistula (AVF) failure. A murine AVF model was modified to create a partial ligation of the inferior vena cava (IVC) in the outflow of the fistula, mimicking central venous stenosis. Technical aspects of this model are introduced. The aorta and IVC are exposed, following an abdominal incision. The infra-renal aorta and IVC are dissected for proximal clamping, and the distal aorta is exposed for puncture. The IVC at the midpoint between the left renal vein and the aortic bifurcation is carefully dissected to place an 8-0 suture beneath the IVC. After clamping the aorta and IVC, an AVF is created by puncturing the infra-renal aorta through both walls into the IVC with a 25 G needle, followed by ligating a 22 G intra-venous (IV) catheter and IVC together. The catheter is then removed, creating a reproducible venous stenosis without occlusion. The aorta and IVC are unclamped after confirming primary hemostasis. This novel model of central vein stenosis is easy to perform, reproducible, and will facilitate studies on AVF failure.

Male mice underwent the operation mentioned above to create both an AVF and an IVC stenosis. Control mice underwent only laparotomy and dissection of the tissues surrounding the IVC, e.g., a sham procedure, or only creation of an IVC stenosis without simultaneous creation of an AVF.
The IVC was observed with Doppler ultrasound on day 7 after the surgical procedure (Figure 2). The fistula and stenosi...

Watch this Scientific Journal Video about Murine Model of Central Venous Stenosis using Aortocaval Fistula with an Outflow Stenosis at JoVE.com

Murine Model of Central Venous Stenosis using Aortocaval Fistula with an Outflow Stenosis

An aortocaval fistula was created by puncturing the murine infra-renal aorta through both walls into the inferior vena cava and was followed by creation of a stenosis in its outflow via partial ligation of the inferior vena cava. This reproducible model can be used to study central venous stenosis.

Central venous stenosis is an important entity contributing to arteriovenous fistula (AVF) failure. A murine AVF model was modified to create a partial ...

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7.2K Views.  Yale University. An aortocaval fistula was created by puncturing the murine infra-renal aorta through both walls into the inferior vena cava and was followed by creation of a stenosis in its outflow via partial ligation of the inferior vena cava. This reproducible model can be used to study central venous stenosis.

Video: Murine Model of Central Venous Stenosis using Aortocaval Fistula with an Outflow Stenosis

Surgical Management of Meatal Stenosis with Meatoplasty

Meatal stenosis is a common urologic complication after circumcision. Children present to their primary care physicians with complaints of deviated urinary stream, difficult-to-aim, painful urination, and urinary frequency. Clinical exam reveals a pinpoint meatus and if the child is asked to urinate, he will usually have an upward, thin, occasionally forceful urinary stream with incomplete bladder emptying. The mainstay of management is meatoplasty (reconstruction of the distal urethra /meatus). This educational video will demonstrate how this is performed.

Meatoplasty, surgical management of meatal stenosis.

Meatal stenosis is a common urologic complication after circumcision.  Children present to their primary care physicians with complaints of deviated ...

Using Quantitative Real-time PCR to Determine Donor Cell Engraftment in a Competitive Murine Bone Marrow Transplantation Model

Murine bone marrow transplantation models provide an important tool in measuring hematopoietic stem cell (HSC) functions and determining genes/molecules that regulate HSCs. In these transplant model systems, the function of HSCs is determined by the ability of these cells to engraft and reconstitute lethally irradiated recipient mice. Commonly, the donor cell contribution/engraftment is measured by antibodies to donor- specific cell surface proteins using flow cytometry. However, this method heavily depends on the specificity and the ability of the cell surface marker to differentiate donor-derived cells from recipient-originated cells, which may not be available for all mouse strains. Considering the various backgrounds of genetically modified mouse strains in the market, this cell surface/ flow cytometry-based method has significant limitations especially in mouse strains that lack well-defined surface markers to separate donor cells from congenic recipient cells. Here, we reported a PCR-based technique to determine donor cell engraftment/contribution in transplant recipient mice. We transplanted male donor bone marrow HSCs to lethally irradiated congenic female mice. Peripheral blood samples were collected at different time points post transplantation. Bone marrow samples were obtained at the end of the experiments. Genomic DNA was isolated and the Y chromosome specific gene, Zfy1, was amplified using quantitative Real time PCR. The engraftment of male donor-derived cells in the female recipient mice was calculated against standard curve with known percentage of male vs. female DNAs. Bcl2 was used as a reference gene to normalize the total DNA amount. Our data suggested that this approach reliably determines donor cell engraftment and provides a useful, yet simple method in measuring hematopoietic cell reconstitution in murine bone marrow transplantation models. Our method can be routinely performed in most laboratories because no costly equipment such as flow cytometry is required.

Determining donor cell engraftment presents a challenge in mouse bone marrow transplant models that lack well-defined phenotypical markers. We described a methodology to quantify male donor cell engraftment in female transplant recipient mice. This method can be used in all mouse strains for the study of HSC functions.

Murine bone marrow transplantation models provide an important tool in measuring hematopoietic stem cell (HSC) functions and determining genes/molecules ...

Technical Aspects of the Mouse Aortocaval Fistula

Technical aspects of creating an arteriovenous fistula in the mouse are discussed. Under general anesthesia, an abdominal incision is made, and the aorta and inferior vena cava (IVC) are exposed. The proximal infrarenal aorta and the distal aorta are dissected for clamp placement and needle puncture, respectively. Special attention is paid to avoid dissection between the aorta and the IVC. After clamping the aorta, a 25 G needle is used to puncture both walls of the aorta into the IVC. The surrounding connective tissue is used for hemostatic compression. Successful creation of the AVF will show pulsatile arterial blood flow in the IVC. Further confirmation of successful AVF can be achieved by post-operative Doppler ultrasound.

The goal is to produce an arteriovenous fistula that is simple and reproducible. This method does not use sutures or glue adhesive. Therefore the samples can be used with the least amount of foreign materials for analysis.

Technical aspects of creating an arteriovenous fistula in the mouse are discussed. Under general anesthesia, an abdominal incision is made, and the aorta ...

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

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

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

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

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 ...

Left Atrial Stenosis Induced Pulmonary Venous Arterialization and Group 2 Pulmonary Hypertension in Rat

The mechanism of mitral stenosis-induced pulmonary venous arterialization and group 2 pulmonary hypertension (PH) is unclear. There is no rodent model of group 2 PH, due to mitral stenosis (MS), to facilitate the investigation of disease mechanisms and potential therapeutic strategies. We present a novel rat model of pulmonary venous congestion-induced pulmonary venous arterialization and group 2 PH caused by left atrial stenosis (LAS). LAS is achieved by constricting the left atrium using a half-closed titanium clip. After the LAS surgery, a rat model with a transmitral inflow velocity greater than or equal to 2.0 m/s on echocardiography gradually develops pulmonary venous arterialization and group 2 PH over an 8- to 10-week period. In this protocol, we provide the step-by-step procedure of how to perform the LAS surgery. The presented LAS rat model mimics MS in humans and is useful for studying the underlying molecular mechanism of pulmonary venous arterialization and for the preclinical evaluation of therapies for group 2 PH.

Left atrial stenosis (LAS) is a novel surgical technique used for studying group 2 pulmonary hypertension (PH) and mechanisms underlying pulmonary venous arterialization. Here, we present a protocol to constrict the left atrium using a titanium clip to cause pulmonary venous arterialization and moderate PH in a rat.

The mechanism of mitral stenosis-induced pulmonary venous arterialization and group 2 pulmonary hypertension (PH) is unclear. There is no rodent model of ...

A Modified Two Kidney One Clip Mouse Model of Renin Regulation in Renal Artery Stenosis

Renal artery stenosis is a common condition in patients with coronary or peripheral vascular disease where the renin angiotensin aldosterone system (RAAS) is overactivated. In this context, there is a narrowing of the renal arteries that stimulate an increase in the expression and release of renin, the rate-limiting protease in RAAS. The resulting rise in renin expression is a known driver of renovascular hypertension, frequently associated with kidney injury and end organ damage. Thus, there is a great interest in developing novel treatments for this condition. The molecular and cellular mechanism of renin control in renal artery stenosis is not fully understood and warrants further investigation. To induce renal artery stenosis in mice, a modified 2 kidney 1 clip (2K1C) Goldblatt mouse model was developed. The right kidney was stenosed in wild type mice and sham operated mice were used as control. After renal artery stenosis, we determined renin expression and kidney injury. Kidneys were harvested, and fresh cortices were used to determine protein and mRNA expression of renin. This animal model is reproducible and can be used to study pathophysiological responses, molecular and cellular pathways involved in renovascular hypertension and kidney injury.

A modified 2 kidney 1 clip (2K1C) Goldblatt mouse model was developed using polyurethane tubing to initiate renal artery stenosis, inducing an increase in renin expression and kidney injury. Here, we describe a detailed procedure of preparing and placing the cuff onto the renal artery to generate a reproducible and consistent 2K1C mouse model.

Renal artery stenosis is a common condition in patients with coronary or peripheral vascular disease where the renin angiotensin aldosterone system (RAAS) ...

A Rabbit Aortic Valve Stenosis Model Induced by Direct Balloon Injury

Animal models are emerging as an important tool to understand the pathologic mechanisms underlying aortic valve stenosis (AVS) because of the lack of access to reliable sources of diseased human aortic valves. Among the various animal models, AVS rabbit models are one of the most commonly used in large animal studies. However, traditional AVS rabbit models require a long-term period of dietary supplementation and genetic manipulation to induce significant stenosis in the aortic valve, limiting their use in experimental studies. To address these limitations, a new AVS rabbit model is proposed, in which stenosis is induced by a direct balloon injury to the aortic valve. The present protocol describes a successful technique for inducing AVS in New Zealand white (NZW) rabbits, with step-by-step procedures for the preparation, the surgical procedure, and the post-operative care. This simple and reproducible model offers a promising approach for studying the initiation and progression of AVS and provides a valuable tool for investigating the underlying pathological mechanisms of the disease.

An appropriate animal model is needed to understand the pathologic mechanisms underlying aortic valve stenosis (AVS) and to evaluate the efficacy of therapeutic interventions. The present protocol describes a new procedure for developing the AVS rabbit model via a direct balloon injury in vivo.

Animal models are emerging as an important tool to understand the pathologic mechanisms underlying aortic valve stenosis (AVS) because of the lack of ...

Development of an Effective Mice Model for Studying Oronasal Fistulas

Establishment of an Oronasal Fistula Mice Model

This study presents a method utilizing heated ophthalmologic cautery to develop a viable model for investigating oronasal fistulas. C57BL/6 mice were used to establish the oronasal fistula (ONF) model. To create the ONF, the mice were anesthetized, immobilized, and their hard palates were exposed. During the surgical procedure, a 2.0 x 1.5 mm full-thickness mucosal injury was induced in the midline of the hard palate using ophthalmologic cautery. It was crucial to control the size of the ONF and minimize bleeding in order to ensure the success of the experiment. Verification of the ONF model's effectiveness was conducted on the 7th-day post-operation, encompassing both anatomical and functional assessments. The presence of the nasal septum within the oral cavity and the outflow of sterile water from the nostrils upon injection into the oral cavity confirmed the successful establishment of the ONF model. The model demonstrated a practical and successful oronasal fistula, characterized by a low mortality rate, significant weight changes, and minimal variation in ONF size. Future studies may consider adopting this methodology to elucidate the mechanisms of palate wound healing and explore novel treatments for oronasal fistulas.

Author Spotlight: Investigating Wound Healing in Mice Models of Oronasal Fistulas 

This article outlines a step-by-step procedure for establishing a mice model with an oronasal fistula. The oronasal fistula was created by employing heated ophthalmologic cautery to damage the midline portion of the hard palate, resulting in the formation of an opening between the oral and nasal cavities.

This study presents a method utilizing heated ophthalmologic cautery to develop a viable model for investigating oronasal fistulas. C57BL/6 mice were used ...

Ascending Aortic Banding for Studying Pressure-Overload Induced Heart Failure

A Minimally Invasive Model of Aortic Stenosis in Swine

Large animal models of heart failure play an essential role in the development of new therapeutic interventions due to their size and physiological similarities to humans. Efforts have been dedicated to creating a model of pressure-overload induced heart failure, and ascending aortic banding while still supra-coronary and not a perfect mimic of aortic stenosis in humans, closely resembling the human condition.
The purpose of this study is to demonstrate a minimally invasive approach to induce left ventricular pressure overload by placing an aortic band, precisely calibrated with percutaneously introduced high-fidelity pressure sensors. This method represents a refinement of the surgical procedure (3Rs), resulting in homogenous trans-stenotic gradients and reduced intragroup variability. Additionally, it enables swift and uneventful animal recovery, leading to minimal mortality rates. Throughout the study, animals were followed for up to 2 months after surgery, employing transthoracic echocardiography and pressure-volume loop analysis. However, longer follow-up periods can be achieved if desired. This large animal model proves valuable for testing new drugs, particularly those targeting hypertrophy and the structural and functional alterations associated with left ventricular pressure overload.

Author Spotlight: Development of a Minimally Invasive Large-Animal Model for Reliable and Reproducible Cardiovascular Research 

This protocol describes a minimally invasive surgical procedure for ascending aortic banding in swine.

Large animal models of heart failure play an essential role in the development of new therapeutic interventions due to their size and physiological ...