This study was supported by a grant from the Dutch Kidney Foundation (KJPB 08.0003). 
Carolien Rothuizen is acknowledged for her contribution to the study. Hoang Pham is acknowledged for his assistance with the pathology work-up.

All experiments were approved by the committee on animal welfare of the Leiden University Medical Center.
1. Animal Preparation and Anaesthesia
<ol>
	<li>Anesthetize the mouse (1-3 months old) in a continuous anaesthetic induction chamber filled with 3-4% isoflurane.</li>
	<li>Shave the ventral side of the neck and the inside part of the left upper leg using an electrical razor and use a piece of tape to remove the hair.</li>
	<li>Apply ocular ointment on both eyes.</li>
	<li>Position the animal on the heating blanket on which the nose ventilation mask is fixed. Fixate the head to the nose mask using adhesive tape.
	<ol>
		<li>Deliver isoflurane at a concentration of 1.5-2.0% using oxygen enriched air set at the following flow: air 0.3 L/min, 100% oxygen 0.2 L/min. Pinch the skin between the toes to assess the depth of anaesthesia and adjust the concentration of isoflurane if needed.</li>
	</ol>
	</li>
	<li>Fixate the animal to the heating blanket with adhesive tape on all the limbs that is set at approximately 37 &#176;C in a supine position.</li>
	<li>Inject buprenorphine dissolved in sodium chloride (NaCl) 0.9% at a dosage of 0.1 mg/kg together with 0.5 ml&#160;of sterile NaCl 0.9% subcutaneously in the flank of the animal.</li>
	<li>Apply chlorhexidine tincture 0.5% to the prepared area.</li>
</ol>
2. Skin Incision
<ol>
	<li>Position the animal under the microscope with its head towards the surgeon.</li>
	<li>Make a longitudinal incision of approximately 1.5 cm in the midline of the ventral neck using a micro scissor.</li>
	<li>Grab the salivary glands with forceps and displace the right salivary gland cranially until it is partly outside the wound.</li>
</ol>
3. Dissecting and Preparing the Vein

<ol>
	<li>Identify and bluntly dissect the dorsomedial branch of the right external jugular vein completely from its perivascular tissue by spreading just alongside and in the direction of the blood vessel.</li>
	<li>Place a loop (10.0 suture) around the dissected vein and apply one knot without locking it.</li>
</ol>
4. Removing the Sternocleidomastoid Muscle
<ol>
	<li>Using forceps, bluntly dissect the right sternocleidomastoid muscle from its surroundings by spreading along its border. Place a pair of open forceps under the isolated muscle and ligate it proximally and distally with a 6.0 suture. Subsequently, excise the muscle using a cauterizer.</li>
</ol>
5. Dissecting and Preparing the Common Carotid Artery
<ol>
	<li>Identify and dissect the right common carotid artery using forceps. Place a 6.0 suture thread around the artery to aid in the manipulation of the artery.</li>
	<li>Apply vascular clamps as distally and proximally as possible.</li>
	<li>Make a longitudinal incision in the middle of the artery of approximately 1 mm using the specialised micro scissor.</li>
	<li>Rinse the artery with a heparin solution [100 IU/ml] until the vessel is clear of blood.</li>
	<li>Measure and adjust the length of the incision if necessary to match the width the vascular clamp [1.1 mm].</li>
</ol>
6. Ligation of the Vein
<ol>
	<li>Apply a vascular clamp proximally of the already prepared vein and place a suture thread around the vein.</li>
	<li>Apply gentle caudal traction to the vein using a haemostat that is placed on the suture thread and ligate the vein as distally as possible using the 10.0 suture that was placed earlier.</li>
	<li>Cut the vein using a scissor just proximally to the ligation.</li>
	<li>Using vascular forceps, gently open the lumen of the vein and rinse it with a heparin solution [100 IU/ml].</li>
</ol>
7. Creation of Anastomosis Part 1
<ol>
	<li>Connect the vein to the artery with an interrupted suture (10.0) using 2 square knots at the twelve o&#39;clock position followed by a suture at the six o&#39;clock position. Make sure to connect the vein to the artery without allowing it to rotate around its own axis. Rotate the animal in order to improve the surgical exposure.</li>
	<li>Position a suture thread around the vein and apply gentle lateral traction using a haemostat.</li>
	<li>Using the same interrupted sutures, complete the anastomosis by placing approximately 3-4 additional sutures at the visible ventral side of the anastomosis.</li>
</ol>
8. Heparin Administration
<ol>
	<li>Rotate heating blanket 180&#176; and focus the microscope on the left upper leg.</li>
	<li>Identify the femoral vein/artery/nerve bundle by looking for a vascular structure that runs longitudinally in the medial part of the upper leg and can be seen through the skin. Make an incision with the micro scissor of approximately 1 cm directly above the femoral vein in a lengthwise manner.</li>
	<li>Carefully dissect the perivascular tissue of femoral vein and inject heparin at a dose of 0.2 IU/g bodyweight in the femoral vein.</li>
</ol>
9. Creation of Anastomosis Part 2
<ol>
	<li>Return to the neck area and remove the suture thread that was placed around the vein.</li>
	<li>Place a suture thread (6.0) that subsequently passes below the carotid artery, over the vein and again below the carotid artery. (Figure 1L)</li>
	<li>Remove the venous vascular clamp.</li>
	<li>Next, twist the half completed arteriovenous fistula 180&#176; along the axis of the carotid artery in a clockwise manner by simultaneously twisting both the vascular clamps and apply medial traction to the ends of the suture thread.</li>
	<li>Complete the anastomosis in the same fashion as is described in step 7.2.</li>
</ol>
10. Vascular Clamp Removal
<ol>
	<li>Remove the suture thread and rotate the vascular clamps 180&#176; counter clockwise.</li>
	<li>Remove the distal vascular clamp followed by the proximal vascular clamp.</li>
	<li>Assess the patency of the anastomosis by gently occluding the venous outflow tract with the vascular forceps. In case of a patent anastomosis, the pre-occluding venous section will expand in a pulsatile fashion. Relocate the right salivary gland to its original anatomical position using forceps.</li>
</ol>
11. Skin Closure and Postoperative Care
<ol>
	<li>Close the skin of the upper leg with an uninterrupted suture (6.0).</li>
	<li>Close the skin of the neck with an uninterrupted suture (6.0).</li>
	<li>Remove the animal from the heating blanket and inject 0.5 ml NaCl 0.9% subcutaneously.</li>
	<li>Place the animal in a darkened cage that is heated with a heating lamp and let it recover fully. When an animal does not recover fully, make sure it does not suffer from a hemodynamic shock due to bleeding in the surgical area. Look for signs such as a swollen neck and the leakage of blood.</li>
	<li>After approximately 6 hr&#160;after the first injection of buprenorphine, inject a single dose of a sustained-release formulation of buprenorphine subcutaneously in a dose that is recommended by the manufacturer, in order to provide adequate analgesia for an additional 72 hr.&#160; &#160;</li>
</ol>
12. Tissue Harvesting
<ol>
	<li>Anesthetize the animal with an anesthetic-mixture containing midazolam (5 mg/kg), medetomidine (0.5 mg/kg) and fentanyl (0.05 mg/kg) administered intraperitoneally.</li>
	<li>Fixate the animal in a supine position by inserting needles through its paws and cheeks into a non-heated silicon mat.</li>
	<li>Make an incision of approximately 1.5-2.0 cm over the scar in the neck with the micro scissor.</li>
	<li>Dissect the AVF, and place suture threads (6.0) around the proximal-, distal artery and venous outflow tract for easy identification.</li>
	<li>Assess the patency of the AVF as is described in section 10.3 of the protocol.</li>
	<li>Open the peritoneal cavity by performing a medial laparotomy using the micro scissor.
	<ol>
		<li>Cut through the left and right ventral rib cage using a pair of scissors starting caudally in the midclavicular line. Using a micro scissor, transect the diaphragm that is attached to the middle part of the ventral rib cage and subsequently displace this section cranially using forceps.</li>
		<li>Locate the inferior caval vein and transect it with a micro scissor.</li>
	</ol>
	</li>
	<li>Insert a needle 23 gauge needle in the left ventricle and perfuse with PBS at a pressure of approximately 100 mmHg until the intravasal fluid is nearly clear.</li>
	<li>Without removing the needle, now perfuse with 4% formalin for 10 min at a pressure of approximately 100 mmHg.</li>
	<li>Excise the AVF by transecting both the arteries and vein with the micro scissor and submerge it in a 4% formalin solution O/N.</li>
</ol>
13. Tissue Embedding and Sectioning
<ol>
	<li>Process the tissue to paraffin according to the manufacture&#39;s protocol. The protocol applied consisted of the following:
	<ol>
		<li>Immerse in Ethanol 70% for 1 hr at RT. Repeat 2x.</li>
		<li>Immerse in Ethanol 96% for 1 hr at RT. Repeat 2x.</li>
		<li>Immerse in Ethanol 99.5% for 1 hr at RT. Repeat once.</li>
		<li>Immerse in Ethanol 99.5% for 1.5 hr at RT.</li>
		<li>Immerse in xylene 100% for 1 hr at RT. Repeat once.</li>
		<li>Immerse in Parafin for 1 hr at 62 &#176;C. Repeat 2x.</li>
	</ol>
	</li>
	<li>Embed the AVF in paraffin so that the venous outflow tract is orientated perpendicular to the embedding cassette.</li>
	<li>Using a microtome, create 12 serial sections each consisting of 30 sections with a 5 &#181;m thickness. Then of each serial section, place one section on a single mounting glass starting from position one up to twelve in an orderly fashion starting with the area closest to the anastomosis.</li>
</ol>

<ol>
	<li>Rotmans, J. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Animal+Models+for+Studying+Pathophysiology+of+Hemodialysis+Access.">Animal Models for Studying Pathophysiology of Hemodialysis Access.</a> The Open Urology &amp; Nephrology Journal. 7, 14-21 (2014).</li><li>Kwei, 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=Early+adaptive+responses+of+the+vascular+wall+during+venous+arterialization+in+mice.">Early adaptive responses of the vascular wall during venous arterialization in mice.</a> Am.J.Pathol. 164 (1), 81-89 (2004).</li><li>Castier, Y., 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=Characterization+of+neointima+lesions+associated+with+arteriovenous+fistulas+in+a+mouse+model.">Characterization of neointima lesions associated with arteriovenous fistulas in a mouse model.</a> Kidney Int. 70 (2), 315-320 (2006).</li><li>Krishnamoorthy, M. 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=Hemodynamic+wall+shear+stress+profiles+influence+the+magnitude+and+pattern+of+stenosis+in+a+pig+AV+fistula.">Hemodynamic wall shear stress profiles influence the magnitude and pattern of stenosis in a pig AV fistula.</a> Kidney Int. 74 (11), 1410-1419 (2008).</li><li>Ene-Iordache, B., Cattaneo, L., Dubini, G., 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=Effect+of+anastomosis+angle+on+the+localization+of+disturbed+flow+in+'side-to-end'+fistulae+for+haemodialysis+access.">Effect of anastomosis angle on the localization of disturbed flow in 'side-to-end' fistulae for haemodialysis access.</a> Nephrol. Dial. Transplant. 28 (4), 997-1005 (2013).</li><li>Wong, C. Y., 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=Vascular+remodeling+and+intimal+hyperplasia+in+a+novel+murine+model+of+arteriovenous+fistula+failure.">Vascular remodeling and intimal hyperplasia in a novel murine model of arteriovenous fistula failure.</a> J.Vasc.Surg. 59 (1), 192-201 (2014).</li><li>Rekhter, M., Nicholls, S., Ferguson, M., Gordon, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+proliferation+in+human+arteriovenous+fistulas+used+for+hemodialysis.">Cell proliferation in human arteriovenous fistulas used for hemodialysis.</a> Arterioscler. 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The authors have nothing to disclose.&#160;

The AVF is considered to be the Achilles&#39; heel in hemodialysis treatment. Unfortunately, the AVF still suffers from a high number of failure8-10. Despite extensive research on the underlying mechanisms, the exact pathophysiology remains unknown. Numerous murine models for AVF failure have already been described in literature2,3,11,12. However, none of these models incorporate a venous end to arterial side anastomosis configuration that is most used in the clinical situation. This is very relevan...

A functional vascular access conduit is of vital importance for patients with renal failure that depend on chronic hemodialysis to stay alive. The construction of an arteriovenous fistula (AVF) is currently the preferred choice for vascular access. However, AVF related complications constitute a major cause of morbidity for patients on chronic hemodialysis. Despite extensive scientific efforts, none of the novel approaches to reduce AVF access-related complications did result in substantial improvement of AVF durability. Part of this disappointing progress relates to incomplete understanding of the underlying pathophysiology of hemodialysis access failure.
To unravel the pathophysiology of AV access failure, animal models that closely mimic human pathology are of utmost importance. In this respect, not only the animal species but also the anastomotic site, the required anti-coagulatory therapy and the duration of follow up after surgery should be taken into account1. While large animals are the most suitable for intervention studies aimed to develop new therapeutic strategies, murine models have the greatest potential to gain more insight in the molecular mechanisms underlying AV access failure due to the availability of transgenic mice. In addition, a large number of mice can be used for this purpose at lower costs compared to larger animal use.
The first murine model of AVF failure was described in 2004 by Kwei and et al.2 In this model, AVFs were constructed using the carotid artery and the jugular vein in an end-to-end manner using an intravascular catheter. This model could be useful to study early venous adaptation in AVFs although the end-to-end configuration and the presence of an intravascular catheter limit the validity of this model for human AVFs. An improved AVF model was introduced by Castier and et al.3 in which the end of the carotid artery is connected to the side of the jugular vein. However, AVFs in hemodialysis patients are usually constructed by anatomizing the end of a vein to the side of an artery. The exact configuration of the AVF is a crucial characteristic of an AV access model since it determines the hemodynamic profile within the conduit4. The latter is an important contributor to endothelial dysfunction and subsequent development of intimal hyperplasia (IH)5.
A novel murine model was recently developed with an identical anatomical configuration as is utilized in humans6. In this model, AVF are created in C57BL/6 mice by anastomosing the end of a branch of the external jugular vein to the side of the common carotid artery with interrupted sutures. In the present paper, we focus on the microsurgical procedure of this model in order to facilitate the widespread use of this murine model, aimed to unravel the complex pathophysiology of hemodialysis access failure.

<table border="0" cellpadding="0" cellspacing="0" width="697">
	<tbody>
		<tr height="17">
			<td height="17" style="height:17px;width:247px;">Dissecting microsocpe</td>
			<td style="width:219px;">Leica</td>
			<td style="width:117px;">M80</td>
			<td style="width:115px;"></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Forceps</td>
			<td>Medicon</td>
			<td>07.61.25</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Vascular forceps</td>
			<td>S&#38;T</td>
			<td>JFL-3D.2</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Vascular forceps</td>
			<td>S&#38;T</td>
			<td>D-5a.2</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Forceps</td>
			<td>Roboz</td>
			<td>SS/45</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Micro scissor 5 mm blade</td>
			<td>Fine science tools</td>
			<td>15000-08</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Micro scissor 2 mm blade</td>
			<td>Fine science tools</td>
			<td>15000-03</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Scissor</td>
			<td>Medicon</td>
			<td>05.12.21</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Clip applier 1</td>
			<td>S&#38;T</td>
			<td>CAF-4</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Vascular clamp 1</td>
			<td>S&#38;T</td>
			<td>B-1V</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Clip applier 2</td>
			<td>BBraun</td>
			<td>FE572K</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Vascular clamp 2</td>
			<td>BBraun</td>
			<td>FE740K</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Hemostatic forceps</td>
			<td>BBraun</td>
			<td>BH110</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">10.0 sutures</td>
			<td>BBraun</td>
			<td>G1117041</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">6.0 sutures</td>
			<td>BBraun</td>
			<td>768464</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Cauterizer</td>
			<td>Fine science tools</td>
			<td>18010-00</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Needle holder</td>
			<td>Medicon</td>
			<td>11.82.18</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Ocular ointment</td>
			<td>Pharmachemie</td>
			<td>41821101</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Chlorhexidine tincture 0,5%</td>
			<td>Leiden University Medical Center</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Heparin</td>
			<td>Leo Pharma</td>
			<td>012866-08</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Buprenorphin</td>
			<td>RB Pharmaceuticals&#160;</td>
			<td>283732</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Isoflurane</td>
			<td>Pharmachemie</td>
			<td>45,112,110</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Anesthesia mask</td>
			<td>Maastricht university</td>
			<td>custom made</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Midazolam</td>
			<td>Actavis</td>
			<td>AAAC6877</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Dexmedetomidine</td>
			<td>Orion</td>
			<td>141-267</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Fentanyl</td>
			<td>Bipharma</td>
			<td>15923002</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Continuous anaesthetic induction chamber</td>
			<td>Vet-tech solutions</td>
			<td>AN010R</td>
			<td></td>
		</tr>
	</tbody>
</table>

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.

After the creation of the anastomosis (Figure 1), the patency should be assessed by shortly occluding the venous outflow tract with a vascular forceps. When the anastomosis is patent, the vascular tract proximal to the occlusion should clearly expand in a pulsatile manner. In addition, the patency is confirmed by using near infrared fluoroscopy (NIRF) that effectively functions as an angiography (Figure 2). A failure in the surgical procedure can lead to an occlusion of the anastomosis a...

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

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 ...

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12.9K Views.  Leiden University Medical Center. 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.

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

A Novel Surgical Approach for Intratracheal Administration of Bioactive Agents in a Fetal Mouse Model

Prenatal pulmonary delivery of cells, genes or pharmacologic agents could provide the basis for new therapeutic strategies for a variety of genetic and acquired diseases. Apart from congenital or inherited abnormalities with the requirement for long-term expression of the delivered gene, several non-inherited perinatal conditions, where short-term gene expression or pharmacological intervention is sufficient to achieve therapeutic effects, are considered as potential future indications for this kind of approach. Candidate diseases for the application of short-term prenatal therapy could be the transient neonatal deficiency of surfactant protein B causing neonatal respiratory distress syndrome1,2 or hyperoxic injuries of the neonatal lung3. Candidate diseases for permanent therapeutic correction are Cystic Fibrosis (CF)4, genetic variants of surfactant deficiencies5 and &alpha;1-antitrypsin deficiency6.
Generally, an important advantage of prenatal gene therapy is the ability to start therapeutic intervention early in development, at or even prior to clinical manifestations in the patient, thus preventing irreparable damage to the individual. In addition, fetal organs have an increased cell proliferation rate as compared to adult organs, which could allow a more efficient gene or stem cell transfer into the fetus. Furthermore, in utero gene delivery is performed when the individual's immune system is not completely mature. Therefore, transplantation of heterologous cells or supplementation of a non-functional or absent protein with a correct version should not cause immune sensitization to the cell, vector or transgene product, which has recently been proven to be the case with both cellular and genetic therapies7.
In the present study, we investigated the potential to directly target the fetal trachea in a mouse model. This procedure is in use in larger animal models such as rabbits and sheep8, and even in a clinical setting9, but has to date not been performed before in a mouse model. When studying the potential of fetal gene therapy for genetic diseases such as CF, the mouse model is very useful as a first proof-of-concept because of the wide availability of different transgenic mouse strains, the well documented embryogenesis and fetal development, less stringent ethical regulations, short gestation and the large litter size.
Different access routes have been described to target the fetal rodent lung, including intra-amniotic injection10-12, (ultrasound-guided) intrapulmonary injection13,14 and intravenous administration into the yolk sac vessels15,16 or umbilical vein17. Our novel surgical procedure enables researchers to inject the agent of choice directly into the fetal mouse trachea which allows for a more efficient delivery to the airways than existing techniques18.

We developed a novel surgical approach for intratracheal administration of bioactive agents into the mouse fetus. The delivery route is more efficient in targeting the fetal mouse lungs than the commonly used intra-amniotic injection. This procedure has to date not been described in a mouse model.

Prenatal pulmonary delivery of cells, genes or pharmacologic agents could provide the basis for new therapeutic strategies for a variety of genetic and ...

Murine Model of Wound Healing

Wound healing and repair are the most complex biological processes that occur in human life. After injury, multiple biological pathways become activated. Impaired wound healing, which occurs in diabetic patients for example, can lead to severe unfavorable outcomes such as amputation. There is, therefore, an increasing impetus to develop novel agents that promote wound repair. The testing of these has been limited to large animal models such as swine, which are often impractical. Mice represent the ideal preclinical model, as they are economical and amenable to genetic manipulation, which allows for mechanistic investigation. However, wound healing in a mouse is fundamentally different to that of humans as it primarily occurs via contraction. Our murine model overcomes this by incorporating a splint around the wound. By splinting the wound, the repair process is then dependent on epithelialization, cellular proliferation and angiogenesis, which closely mirror the biological processes of human wound healing. Whilst requiring consistency and care, this murine model does not involve complicated surgical techniques and allows for the robust testing of promising agents that may, for example, promote angiogenesis or inhibit inflammation. Furthermore, each mouse acts as its own control as two wounds are prepared, enabling the application of both the test compound and the vehicle control on the same animal. In conclusion, we demonstrate a practical, easy-to-learn, and robust model of wound healing, which is comparable to that of humans.

A murine model of cutaneous wound healing that can be used to assess therapeutic compounds in physiological and pathophysiological settings.

Wound healing and repair are the most complex biological processes that occur in human life. After injury, multiple biological pathways become activated. ...

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 Surgical Procedure for Resecting the Mouse Rib: A Model for Large-Scale Long Bone Repair

This protocol introduces researchers to a new model for large-scale bone repair utilizing the mouse rib. The procedure details the following: preparation of the animal for surgery, opening the thoracic body wall, exposing the desired rib from the surrounding intercostal muscles, excising the desired section of rib without inducing a pneumothorax, and closing the incisions. Compared to the bones of the appendicular skeleton, the ribs are highly accessible. In addition, no internal or external fixator is necessary since the adjacent ribs provide a natural fixation. The surgery uses commercially available supplies, is straightforward to learn, and well-tolerated by the animal. The procedure can be carried out with or without removing the surrounding periosteum, and therefore the contribution of the periosteum to repair can be assessed. Results indicate that if the periosteum is retained, robust repair occurs in 1 - 2 months. We expect that use of this protocol will stimulate research into rib repair and that the findings will facilitate the development of new ways to stimulate bone repair in other locations around the body.

The overall goal of this procedure is to successfully resect a portion of bone from the rib of a mouse. The procedure was developed as a model to study large-scale long bone repair.

This protocol introduces researchers to a new model for large-scale bone repair utilizing the mouse rib. The procedure details the following: preparation ...

Intraluminal Drug Delivery to the Mouse Arteriovenous Fistula Endothelium

Delivery of therapeutic agents to enhance arteriovenous fistula (AVF) maturation can be administered either via intraluminal or external routes. The simple murine AVF model was combined with intraluminal administration of drug solution to the venous endothelium at the same time as fistula creation. Technical aspects of this model are discussed. Under general anesthesia, an abdominal incision is made and the aorta and inferior vena cava (IVC) are exposed. The infra-renal aorta and IVC are dissected for clamping. After proximal and distal clamping, the puncture site is exposed and a 25 G needle is used to puncture both walls of the aorta and into the IVC. Immediately after the puncture, a reporter gene-expressing viral vector was infused in the IVC via the same needle, followed by 15 min of incubation. The intraluminal administration method enabled more robust viral gene delivery to the venous endothelium compared to administration by the external route. This novel method of delivery will facilitate studies that explore the role of the endothelium in AVF maturation and enable intraluminal drug delivery at the time of surgical operation.

After puncturing the aorta through the inferior vena cava (IVC) to create an aorto-caval fistula in the mouse, solution containing a drug is infused into the IVC via the same needle, followed by incubation. This method enables more robust drug delivery to the venous endothelium compared to the external route.

Delivery of therapeutic agents to enhance arteriovenous fistula (AVF) maturation can be administered either via intraluminal or external routes. The ...

A Rat Model of Orthotopic Liver Transplantation Using a Novel Magnetic Anastomosis Technique for Suprahepatic Vena Cava Reconstruction

The rat model of orthotopic liver transplantation (OLT) is essential for transplant research. It is a very sophisticated animal model and requires a steep learning curve. The introduction of the cuff technique for anastomosis of the portal vein (PV) and infrahepatic vena cava (IHVC) has significantly simplified the transplant procedure in rats. However, due to the short anterior wall of the recipients' suprahepatic vena cava (SHVC), the cuff technique is very difficult to use for the reconstruction of the SHVC. Most researchers in this field still use the hand-suture technique for SHVC reconstruction, which makes it the bottleneck step in rat orthotopic liver transplantation. The magnetic anastomosis technique (i.e., magnamosis) is a method of connecting two vessels using the attractive force between two magnets. Our recent study has shown that the magnetic anastomosis technique is superior to the hand-suture technique for SHVC reconstruction in rats. In this article, we show a step-by-step protocol for SHVC reconstruction in rats using the novel magnetic anastomosis technique. In this model, the reconstruction of the PV and IHVC was performed by the standard cuff technique, while the reconstruction of the bile duct (BD) was performed by a stent technique. The hepatic re-arterialization was not performed. The magnetic anastomosis technique made SHVC reconstruction much easier and significantly shortened the anphepatic phase. After a reasonable learning curve, even researchers without advanced microsurgical skills can produce reliable and reproducible results using this rat model of OLT.

The reconstruction of the suprahepatic vena cava (SHVC) remains a difficult step in rat orthotopic liver transplantation. In this article, we show a step-by-step protocol for SHVC reconstruction in rats using a novel magnetic anastomosis technique.

The rat model of orthotopic liver transplantation (OLT) is essential for transplant research. It is a very sophisticated animal model and requires a steep ...

Murine Distal Colostomy, A Novel Model of Diversion Colitis in C57BL/6 Mice

Diversion colitis (DC) is a frequent clinical condition occurring in patients with bowel segments excluded from the fecal stream as a result of a diverting enterostomy. The etiology of this disease remains ill-defined but appears to differ from that of classical inflammatory bowel diseases such as Crohn's disease and ulcerative colitis. Research aimed to decipher the pathophysiological mechanisms leading to the development of this disease has been severely hampered by the lack of an appropriate murine model. This protocol generates a murine model of DC that facilitates the study of the immune system's role and its interaction with the microbiome in the development of DC. In this model using C57BL/6 animals, distal parts of the colon are excluded from the fecal stream by creating a distal colostomy, triggering the development of mild to moderate inflammation in the excluded bowel segments and reproducing the hallmark lesions of human DC with a moderate systemic inflammatory response. In contrast to the rat model, a large number of genetically-modified murine models on the C57BL/6 background are available. The combination of these animals with our model allows the potential roles of individual cytokines, chemokines, or receptors of bioactive molecules (e.g., interleukin (IL)-17; IL-10, chemokine CXCL13, chemokine receptors CXCR5 and CCR7, and the sphingosine-1-phosphate receptor 4) to be assessed in the pathogenesis of DC. The availability of congenic mouse strains on the C57BL/6 background largely facilitates transfer experiments to establish the roles of distinct cell types involved in the etiology of DC. Finally, the model offers the opportunity to assess the influences of local interventions (e.g., modification of the local microbiome or local anti-inflammatory therapy) on mucosal immunity in affected and non-affected bowel segments and the on systemic immune homeostasis.

Murine distal colostomy provides a murine model for human diversion colitis, a predominantly lymphocytic colitis in colon segment excluded from the fecal stream.

Diversion colitis (DC) is a frequent clinical condition occurring in patients with bowel segments excluded from the fecal stream as a result of a ...

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.

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 ...

Murine Surgical Model of Topical Elastase Induced Descending Thoracic Aortic Aneurysm

According to the Center for Disease Control, aortic aneurysms (AAs) were considered a leading cause of death in all races and both sexes from 1999-2016. An aneurysm forms as a result of progressive weakening and eventual dilation of the aorta, which can rupture or tear once it reaches a critical diameter. Aneurysms of the descending aorta in the chest, called descending thoracic aortic aneurysms (dTAA), make up a large proportion of aneurysm cases in the United States. Uncontained dTAA rupture is almost universally lethal, and elective repair has a high rate of morbidity and mortality. The purpose of our model is to study dTAA specifically, to elucidate the pathophysiology of dTAA and to search for molecular targets to halt the growth or reduce the size of dTAA. By having a murine model to study thoracic pathology precisely, targeted therapies can be developed to specifically test dTAA. The method is based on the placement of porcine pancreatic elastase (PPE) directly on the outer murine aortic wall after surgical exposure. This creates a destructive and inflammatory reaction, which weakens the aortic wall and allows for aneurysm formation over weeks to months. Though murine models possess limitations, our dTAA model produces robust aneurysms of predictable size. Furthermore, this model can be used to test genetic and pharmaceutical targets which may arrest dTAA growth or prevent rupture. In human patients, interventions such as these could help avoid aneurysm rupture, and difficult surgical intervention.

We describe a surgical protocol to consistently induce robust descending thoracic aortic aneurysms in mice. The procedure involves left thoracotomy, thoracic aorta exposure, and placement of a sponge soaked in porcine pancreatic elastase on the aortic wall.

According to the Center for Disease Control, aortic aneurysms (AAs) were considered a leading cause of death in all races and both sexes from 1999-2016. ...

Creating Radio-cephalic Arteriovenous Fistula in the Forearm with a Modified No-Touch Technique

Autologous arteriovenous fistula (AVF) is the primary and best option to obtain vascular access for hemodialysis treatment; other options are arteriovenous graft (AVG) and central venous catheterization (CVC). The implementation of radio-cephalic autologous arteriovenous fistula (RC-AVF) in the forearm was preferred among patients with superior vascular conditions. However, there is a high rate of early fistula failure. The chosen surgical method is understood to have an effect on the maturation of the fistula. New surgical procedures such as radial artery deviation and reimplantation (RADAR) have been significantly improved for juxta-anastomotic stenosis. Nevertheless, new problems such as stenosis of arteries and narrowing of surgical indication were also found. In this report, we presented a modified no-touch technique (MNTT) to create an RC-AVF, in which the venous and arterial wall avoid devascularization and the radial artery does not sever.

We present a modified no-touch technique (MNTT) to create a radio-cephalic arteriovenous fistula (RC-AVF) in which the venous and arterial wall avoid devascularization and the radial artery does not sever.