This study is supported by the American Venous Forum (AVF) 2023 Basic Science research grant and Surmodics, Inc.

The following protocol follows the University of Michigan (UMICH) Institutional Animal Care and Use Committee (IACUC) policies and guidelines, the U.S. Government Principles for the Utilization and Care of Vertebrate Animals Used in Testing, Research, and Training, and the ARRIVE guidelines 2.0. The UMICH Animal Welfare Assurance agreement is compliant with OLAW and USDA and is fully accredited by AAALAC International. This protocol was approved with the ID number PRO00010841. Male outbred Sprague Dawley rats from Charles River Laboratories, weighing 450 g and 15 weeks of age, were used.
1. Rat anesthesia
<ol>
	<li>Remove animals from their cage and place them in an anesthetic pre-operative induction gas chamber at 5% isoflurane and 100% oxygen at a flow rate of 0.8 to 1 L/min (vaporizer-controlled) to induce general anesthesia.</li>
	<li>Sedate rats in the anesthetic induction chamber, remove them from the chamber, weigh, lubricate their eyes with sterile ophthalmic ointment, and then place them in dorsal recumbency on a warm water circulating heating device. Confirm adequate depth of anesthesia using pedal reflex (firm toe pinch).</li>
	<li>Shave the ventral abdomen with electric clippers. Maintain general anesthesia at 2.5% isoflurane and 100% oxygen at 0.8 to 1 L/min with a non-rebreathing circuit through a nosecone.</li>
</ol>
2. Rat ultrasound scanning
<ol>
	<li>Monitor physiological assessments, including respiratory rate, heart rate, and temperature, during imaging.</li>
	<li>For abdominal imaging of the Inferior Vena Cava (IVC), apply conducting gel and orient the transducer in a transverse position. While presetting the peripheral vascular, use two-dimensional imaging mode or B-mode, lower the linear probe (10 MHz) on the center of the abdomen, adjusting depth with pressure until the abdominal vessels come into view.</li>
	<li>Differentiate IVC from the abdominal aorta by assessing compressibility and by assessing flow using both color and pulsed-wave Doppler mode with a high-frequency linear probe (10 mHz).
	<ol>
		<li>When applying compression with the ultrasound probe, differentiate the two as the IVC is compressible, whereas the aorta maintains its shape and patency.</li>
	</ol>
	</li>
	<li>Assess the direction and velocity of blood flow by using both color and pulsed-wave Doppler. The color Doppler window represents the flow toward the probe in red and flows away from the probe in blue. Switch the instrument to pulse-wave Doppler mode (Duplex mode) to assess blood flow direction and velocity over time. Acquire necessary flow images by using the ultrasound machine&#39;s automated image capture tool (The exact specifications for image acquisition may vary between ultrasound systems).
	<ol>
		<li>Use the following assessment method: the aorta has blood flow toward the probe and a triphasic waveform, whereas the IVC has spontaneous flow away from the probe with a much lower amplitude.</li>
		<li>If the proximal IVC displays a normal waveform, yet a nonphasic or absent (flat) waveform is detected distally, explore the possibility of a venous obstruction between these points of examination.</li>
	</ol>
	</li>
	<li>Once the IVC is located, identify the mid-section, which is in the middle third portion, inferior to the renal veins and superior to the IVC bifurcation, most likely where the lumbar veins are located.</li>
	<li>Measure at the mid-section IVC the wall-to-wall diameter in the transverse view using the cross-sectional B-mode image, recording the widest diameter of the vessel. Imaging acquisition may vary in different ultrasound machines. Store data using compact disks (CDs) in DICOM files.</li>
</ol>
3. Rat micro-surgery and recovery
<ol>
	<li>Clean the abdomen with gauze-soaked chlorhexidine scrub and chlorhexidine solution 3x to ensure an aseptic surgical condition. Administer buprenorphine extended-release injectable suspension, 0.65 mg/kg subcutaneous (SC), as an analgesic for rats since it does not interfere with the biomarker panels of inflammatory molecules for protein analysis.</li>
	<li>Place sterilized cling film as a surgical wrap to cover the rat thorax and abdominal area, microscope knobs (magnification and focus), and eyepiece.</li>
	<li>Make a ventral midline incision (3 cm) approximately 2 cm below the xiphoid process with iris scissors through the skin and abdominal wall, exposing the abdominal contents. Use sterile saline-soaked 2 inch x 2 inch gauze to reflect the intestines to the animal&#39;s right side.</li>
	<li>For IVC exposure, perform a blunt dissection using a sterile cotton-tipped applicator. Place a wire speculum in the incision, allowing IVC visualization.</li>
	<li>Cauterize all IVC lumbar branches using a low-temperature fine tip cautery, from the renal veins to the iliac bifurcation, and ligate side branches with 7-0 non-absorbable polypropylene sutures.</li>
	<li>Place a proximal curved vascular micro-clip on the IVC, which is separated from the aorta and just inferior to the renal veins. Place a straight microclip on the distal IVC, which is separated from the aorta and superior to the IVC bifurcation.</li>
	<li>Place an 8-0 nylon U stitch suture caudal to the left renal vein centered on the anterior surface of the IVC.</li>
	<li>Insert a 0.014 mm sharpened guidewire with the venoplasty balloon backloaded, retrograde to blood flow into the infrarenal IVC, caudal to the curved micro-clip.</li>
	<li>Advance the balloon into the mid-IVC using the Seldinger technique. Remove the sharpened guidewire and inflate the venoplasty balloon for 3 min with a 10% to 15% IVC overstretch using a 20 mL inflation syringe to generate positive pressure over a range of 0-30 Atm. Flush all systems with sterile saline before IVC canulation to avoid air embolism. 
	NOTE: A 2.8 mm IVC would undergo venoplasty to 3.22 mm (15% overstretch). The required inflation pressure to reach the desired overstretch is determined by the characteristics of the balloon and is available on the manufacturer&#39;s packaging.</li>
	<li>Tighten the U stitch upon venoplasty balloon deflation and removal. Remove the micro-clips.</li>
	<li>Close the laparotomy site in a two-layer fashion. Use a 5-0 polyglactin absorbable synthetic suture in a continuous pattern to close both the abdominal wall and skin.</li>
	<li>Recover rats in an individual cage, observe post-operatively (30 min) under a heating lamp (minimum distance - 24 inch away from the cage), and then return to their original housing units.</li>
	<li>For sham animals from each experimental group, perform only the dissection, without the IVC branches ligation, cauterization, and cannulation.</li>
	<li>For post-thrombotic conditions, place a proximal straight vascular micro-clip on the IVC, which is separated from the aorta, just inferior to the renal veins, for 24 h. Use the same dissection and closing techniques.
	<ol>
		<li>Check for the ultrasound signs of IVC occlusion, which include the visualization of the IVC clip, confirmation of distal IVC without flow, and common iliac veins distended. Follow-up timepoints can be customized to fit the study&#39;s specifications.</li>
		<li>To observe the physiologic changes that are being modeled, select timepoints in the first 72 h for early thrombi formation and from 3 to 7 days postprocedural for later thrombi resolution. Later timepoints tested in this model include 7 to 28 days5,13.</li>
	</ol>
	</li>
	<li>Use the techniques in steps 3.5-3.9 for post-thrombotic balloon venoplasty with the following caveats: A higher insufflator pressure might be required to achieve the desired overstretch since the IVC diameter increases in post-thrombotic conditions.</li>
	<li>Perform euthanasia under the recommendations set forth by the current American Veterinary Medical Association Guidelines on Euthanasia for rodents by performing two confirmatory methods (blood removal and vital organ removal) to ensure the animal will not revive.</li>
</ol>
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/66820/66820fig01.jpg" /> 
Figure 1:&#160;Distribution of transabdominal duplex measures of transverse IVC (mid-infrarenal section) diameter. The measurement was done by animal weight. No significant correlation was found between the weight and the IVC diameter. <a href="https://www.jove.com/files/ftp_upload/66820/66820fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
4. Sample preparation
<ol>
	<li>Perform confirmatory tissue transfer of drug-coated venoplasty balloons using high-performance liquid chromatography (HPLC) assay technique.</li>
	<li>Dissect the IVC and aorta and remove en bloc for formalin-fixed paraffin embedding and histological analysis.</li>
	<li>For protein analysis, use RIPA buffer in a diluting concentration of 60,000 &#181;g/g of sample, process with a tissue homogenizer in low-temperature room settings at 4 &#176;C, and store at -80 &#176;C after processing.</li>
</ol>

Rodent Venoplasty Balloon Model for Deep Vein Treatment Studies

<ol>
	<li>Prandoni, P., 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+long-term+clinical+course+of+acute+deep+venous+thrombosis.">The long-term clinical course of acute deep venous thrombosis.</a> Ann Inter Med. 125 (1), 1-7 (1996).</li><li>Prandoni, P., Kahn, S. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Post-thrombotic+syndrome:+prevalence,+prognostication+and+need+for+progress.">Post-thrombotic syndrome: prevalence, prognostication and need for progress.</a> Br J Haematol. 145 (3), 286-295 (2009).</li><li>Gloviczki, P., 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+2023+Society+for+Vascular+Surgery,+American+Venous+Forum,+and+American+Vein+and+Lymphatic+Society+clinical+practice+guidelines+for+the+management+of+varicose+veins+of+the+lower+extremities.+Part+II.">The 2023 Society for Vascular Surgery, American Venous Forum, and American Vein and Lymphatic Society clinical practice guidelines for the management of varicose veins of the lower extremities. Part II.</a> J Vas Surg Venous Lymph Diso. 12 (1), 101670 (2024).</li><li>Henke, P., Sharma, S., Wakefield, T., Myers, D., Obi, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Insights+from+experimental+post-thrombotic+syndrome+and+potential+for+novel+therapies.">Insights from experimental post-thrombotic syndrome and potential for novel therapies.</a> Transl Res. 225, 95-104 (2020).</li><li>Diaz, J. 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=Choosing+a+mouse+model+of+venous+thrombosis:+A+consensus+assessment+of+utility+and+application.">Choosing a mouse model of venous thrombosis: A consensus assessment of utility and application.</a> Arterioscl Thrombo Vasc Biol. 39 (3), 311-318 (2019).</li><li>Lee, Y. U., Lee, A. Y., Humphrey, J. D., Rausch, M. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Histological+and+biomechanical+changes+in+a+mouse+model+of+venous+thrombus+remodeling.">Histological and biomechanical changes in a mouse model of venous thrombus remodeling.</a> Biorheology. 52 (3), 235-245 (2015).</li><li>Xie, 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=Correspondence+of+ultrasound+elasticity+imaging+to+direct+mechanical+measurement+in+aging+DVT+in+rats.">Correspondence of ultrasound elasticity imaging to direct mechanical measurement in aging DVT in rats.</a> Ultrasound Med Biol. 31 (10), 1351-1359 (2005).</li><li>Moini, 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=Venoplasty+and+stenting+in+post-thrombotic+syndrome+and+non-thrombotic+iliac+vein+lesion.">Venoplasty and stenting in post-thrombotic syndrome and non-thrombotic iliac vein lesion.</a> Minim Invasive Ther Allied Technol. 29 (1), 35-41 (2020).</li><li>Chaitidis, N., 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=Management+of+post-thrombotic+syndrome:+A+comprehensive+review.">Management of post-thrombotic syndrome: A comprehensive review.</a> Curr Pharma Des. 28 (7), 550-559 (2022).</li><li>Dangas, G. 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=In-stent+restenosis+in+the+drug-eluting+stent+era.">In-stent restenosis in the drug-eluting stent era.</a> J Am Coll Cardiol. 56 (23), 1897-1907 (2010).</li><li>Negl&#233;n, P., Berry, M. A., Raju, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endovascular+surgery+in+the+treatment+of+chronic+primary+and+post-thrombotic+iliac+vein+obstruction.">Endovascular surgery in the treatment of chronic primary and post-thrombotic iliac vein obstruction.</a> Euro J Vas Endovas Surg. 20 (6), 560-571 (2000).</li><li>Sharifi, M., Mehdipour, M., Bay, C., Smith, G., Sharifi, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endovenous+therapy+for+deep+venous+thrombosis:+The+TORPEDO+trial.">Endovenous therapy for deep venous thrombosis: The TORPEDO trial.</a> Catheter Cardiovasc Interv. 76 (3), 316-325 (2010).</li><li>Nicklas, J. M., Gordon, A. E., Henke, P. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Resolution+of+deep+venous+thrombosis:+Proposed+immune+paradigms.">Resolution of deep venous thrombosis: Proposed immune paradigms.</a> Int J Mol Sci. 21 (6), 2080 (2020).</li><li>Li, J., Kim, S. G., Blenis, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapamycin:+One+drug,+many+effects.">Rapamycin: One drug, many effects.</a> Cell Metabol. 19 (3), 373-379 (2014).</li><li>Chen, 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=Rapamycin+regulates+Akt+and+ERK+phosphorylation+through+mTORC1+and+mTORC2+signaling+pathways.">Rapamycin regulates Akt and ERK phosphorylation through mTORC1 and mTORC2 signaling pathways.</a> Mol Carcinogen. 49 (6), 603-610 (2010).</li><li>Diaz, J. A., Farris, D. M., Wrobleski, S. K., Myers, D. D., Wakefield, T. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inferior+vena+cava+branch+variations+in+C57BL/6+mice+have+an+impact+on+thrombus+size+in+an+IVC+ligation+(stasis)+model.">Inferior vena cava branch variations in C57BL/6 mice have an impact on thrombus size in an IVC ligation (stasis) model.</a> J Thromb Haemo. 13 (4), 660-664 (2015).</li><li>Sch&#246;nfelder, T., J&#228;ckel, S., Wenzel, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mouse+models+of+deep+vein+thrombosis.">Mouse models of deep vein thrombosis.</a> Gef&#228;sschirurgie. 22 (1), 28-33 (2017).</li><li>de Barros, R. S. 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=Morphometric+analysis+of+rat+femoral+vessels+under+a+video+magnification+system.">Morphometric analysis of rat femoral vessels under a video magnification system.</a> J Vasc Bras. 16 (1), 73-76 (2017).</li></ol>

No conflicts of interest were declared.

The VBM can be performed on rats &#8805; 250 g using balloons in the 2.5-3.5 mm range. For rats exceeding 750 g, the technique is limited by a higher amount of adipose tissue in the abdominal cavity and organ size rather than changes in IVC diameter. From our experience, we have found that 10 or more animals per group are needed to obtain statistical significance between the groups for vein wall protein analysis or activity assays and histology. Periodic temperature control and respiration rate surveillance during surgic...

Deep vein obstructions from unresolved thrombi are a common consequence of deep vein thrombosis (DVT) and are one of the causes of post-thrombotic syndrome (PTS), costing billions of dollars in healthcare and significantly impacting the quality of life1,2,3. PTS is a unique inflammatory pathology with consequent vein wall fibrosis4 not fully captured in small animal DVT models5,6,7, and more importantly, previous models cannot evaluate the response to therapeutic interventions. Thrombotic venous obstructions are often treated by stenting and balloon venoplasty8,9; such interventions are hampered by a high reintervention rate due to restenosis and occlusion10,11,12.
Despite the availability of drug-coated balloons to address arterial-specific stenosis/occlusions, none exist for deep veins. The molecular mechanism behind restenosis is poorly understood in veins and has no direct therapy4. Therefore, our goal is to present an animal model that can test locally delivered therapeutics via venoplasty balloons simulating deep vein post-thrombotic obstructions. This model reproduces the post-thrombotic condition and evaluates how different types of venoplasty balloons affect the vein wall in vivo.

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	<tbody>
		<tr>
			<td>3-0 DemeCRYL</td>
			<td>DemeTech</td>
			<td>G183019F4P</td>
			<td>12 per box</td>
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			<td>5-0 DemeCRYL</td>
			<td>DemeTech</td>
			<td>G285017B0P</td>
			<td>12 per box</td>
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		<tr>
			<td>7-0 DemeLENE</td>
			<td>DemeTech</td>
			<td>PM197011F13M</td>
			<td>12 per box</td>
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		<tr>
			<td>8-0 DemeLON</td>
			<td>DemeTech</td>
			<td>NL868007C7P</td>
			<td>12 per box</td>
		</tr>
		<tr>
			<td>Angled Clip Applier</td>
			<td>SCANLAN</td>
			<td>3795-01A</td>
			<td>7-1/4&#8243; (18.5 cm)</td>
		</tr>
		<tr>
			<td>Baxter 0.9% Sodium Chloride Irrigation Bottle</td>
			<td>Baxter</td>
			<td>SKU: 195-7124</td>
			<td>1000mL Bottle</td>
		</tr>
		<tr>
			<td>Bovie Cautery Low Temperature Fine Tip</td>
			<td>Symmetry Surgical Inc</td>
			<td>AA00</td>
			<td>10/bx</td>
		</tr>
		<tr>
			<td>Buprenorphine</td>
			<td>Fidelis Animal Health</td>
			<td>SKU- 099114</td>
			<td>1.3mg/mL, 3mL</td>
		</tr>
		<tr>
			<td>CD (Sprague Dawley) Rats</td>
			<td>Charles River</td>
			<td>Strain Code 001</td>
			<td>Male, 400 gm</td>
		</tr>
		<tr>
			<td>Clip-It Traceable Timer</td>
			<td>TRACEABLE PRODUCTS</td>
			<td>Cat. No. 5046</td>
			<td></td>
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			<td>Cotton-Tip Applicator 3&#34;</td>
			<td>Dukal Corporation</td>
			<td>922-00037BX100</td>
			<td>1000/BOX</td>
		</tr>
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			<td>Enzymatic Surgical Instrument Detergent and Presoak</td>
			<td>Medline</td>
			<td>MDS88000B9</td>
			<td>1 Gal</td>
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			<td>Eye Lube</td>
			<td>Optixcare</td>
			<td>SKU-065441</td>
			<td>20gm&#160;</td>
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			<td>Gaymar T/Pump Stryker Localized Warming/Cooling Therapy System</td>
			<td>Stryker</td>
			<td>TP700</td>
			<td></td>
		</tr>
		<tr>
			<td>Heifetz Microclips 12mmx2.25mm</td>
			<td>SCANLAN</td>
			<td>3795-20</td>
			<td>Straight</td>
		</tr>
		<tr>
			<td>Heifetz Microclips 12mmx2.25mm</td>
			<td>SCANLAN</td>
			<td>3795-28</td>
			<td>Curved</td>
		</tr>
		<tr>
			<td>Heifetz Microclips 8mmx1.75mm&#160;</td>
			<td>SCANLAN</td>
			<td>3795-14</td>
			<td>Straight</td>
		</tr>
		<tr>
			<td>Heifetz Microclips 8mmx1.75mm&#160;</td>
			<td>SCANLAN</td>
			<td>3795-18</td>
			<td>Curved</td>
		</tr>
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			<td>Inflation device&#160;</td>
			<td>Merit Medical</td>
			<td>IN4130</td>
			<td>BasixCOMPAK with Analog Display</td>
		</tr>
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			<td>Isoflurane</td>
			<td>MFR VETONE</td>
			<td>SKU-501017</td>
			<td>100mL, Liquid for Inhalation</td>
		</tr>
		<tr>
			<td>Microsurgery kit containing tweezers and forceps</td>
			<td>Customized</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Oxygen, E-tank</td>
			<td>Medline</td>
			<td>MDM1630</td>
			<td></td>
		</tr>
		<tr>
			<td>Sharpened Guidewire</td>
			<td>Customized</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Sterile Glad Press-n-Seal</td>
			<td>Glad</td>
			<td>SKU # PSS-140</td>
			<td>ETO Exposed</td>
		</tr>
		<tr>
			<td>Sterile Nonwoven Gauze Sponges 2s 4ply 4x4&#160;</td>
			<td>Medline</td>
			<td>SKU PRM21444H</td>
			<td>100Ct</td>
		</tr>
		<tr>
			<td>Surgical microscope&#160;</td>
			<td>Zeiss</td>
			<td>S100 / OPMI pico</td>
			<td></td>
		</tr>
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			<td>Surgical Scrub &#38; Handwash</td>
			<td>Vetoquinol</td>
			<td>NDC: 17030-003-16</td>
			<td>16 oz</td>
		</tr>
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			<td>Ultrasound Gel</td>
			<td>Medline</td>
			<td>CTR001305</td>
			<td>8.5 oz, 12/CS</td>
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			<td>Ultrasound system</td>
			<td>Siemens</td>
			<td>ACUSON Antares</td>
			<td>3-D, Color, Continuous wave (CW), Pulsed wave (PW), Power CW/CW Spectral</td>
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		<tr>
			<td>Venoplasty Balloon</td>
			<td>Customized</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

rodent inferior vena cava venoplasty balloon model

Balloon venoplasty is a commonly used clinical technique to treat deep vein stenosis and occlusion as a consequence of trauma, congenital anatomic abnormalities, acute deep vein thrombosis (DVT), or stenting. Chronic deep venous obstruction is histopathologically characterized by thrombosis, fibrosis, or both. Currently, no direct treatment is available to target these pathological processes. Therefore, a reliable in vivo animal model to test novel interventions is necessary. The rodent survival inferior vena cava (IVC) venoplasty balloon model (VBM) allows the study of balloon venoplasty in non-thrombotic and post-thrombotic conditions across multiple time points. The local and systemic effect of coated and uncoated venoplasty balloons can be quantified via tissue, thrombus, and blood assays such as real-time polymerase chain reaction (RT-PCR), western blot, enzyme-linked immunosorbent assay (ELISA), zymography, vein wall and thrombus cellular analysis, whole blood and plasma assays, and histological analysis. The VBM is reproducible, replicates surgical human interventions, can identify local vein wall-thrombi protein changes, and allows multiple analyses from the same sample, decreasing the number of animals required per group.

The VBM is a model that evaluates the effect of venoplasty balloons in complete hemostasis control. First, we quantified the IVC (mid-infrarenal section) diameter, as shown in Figure 1, for correct balloon sizing. Second, the developed step-by-step microsurgical technique is illustrated in Figure 2, and we also show examples of the critical steps in Figure 3. Notice the retrograde approach used for the IVC canulation with the sharpe...

Author Spotlight: Utilizing Venoplasty Balloon Model in Rodents to Simulate Surgical Interventions for Deep Veins

The protocol presents a survival rodent model to test venoplasty balloon (VB) interventions in non-thrombotic, thrombotic, and post-thrombotic deep veins.

Rodent Inferior Vena Cava Venoplasty Balloon Model

Balloon venoplasty is a commonly used clinical technique to treat deep vein stenosis and occlusion as a consequence of trauma, congenital anatomic ...

In our laboratory, led by Dr.Andrea Obi, we study a type of abnormal blood clotting, venous thrombosis. In fact, we're one of the very few laboratories in the world working in this promising discovery area. Our goal is to take our findings and translate them into new, safer, more effective approaches to treat venous thrombosis.Our work has led us to look more closely at the role of the immune system, including the presence of infection in thrombus formation, as well as the pathways leading to clot resolution, venous fibrosis, including vein wall scarring and post-thrombotic syndrome. No previous animal model has been able to replicate the complex immune interactions that occur in venous thromboembolism in humans. Additionally, no model has been able to characterize the response to endovascular treatments followed by ultrasound.We are making important contributions to understand how different types of immune cells interact with environment around a blood clot, and how those interactions can lead to changes in the expression of cell's genetics code, a process now as epigenetic regulation. We believe that Inferior Vena Cava Venoplasty Balloon Model will accelerate the development of novel balloon angioplasty prototypes for the treatment of venous thrombosis, and the possibility for prevention of post-thrombotic syndrome.

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Research

JoVE Journal

Medicine

410 Views.  University of Michigan. In our laboratory, led by Dr.Andrea Obi, we study a type of abnormal blood clotting, venous thrombosis. In fact, we're one of the very few laboratories in the world working in this promising discovery area. Our goal is to take our findings and translate them into new, safer, more effective approaches to treat venous thrombosis.Our work has led us to look more closely at the role of the immune system, including the presence of infection in thrombus formation, as well as the pathways lea...

Video: Author Spotlight: Utilizing Venoplasty Balloon Model in Rodents to Simulate Surgical Interventions for Deep Veins

Electrolytic Inferior Vena Cava Model (EIM) of Venous Thrombosis

Animal models serve a vital role in deep venous thrombosis (DVT) research in order to study thrombus formation, thrombus resolution and to test potential therapeutic compounds (1). New compounds to be utilized in the treatment and prevention of DVT are currently being developed. The delivery of potential therapeutic antagonist compounds to an affected thrombosed vein has been problematic. In the context of therapeutic applications, a model that uses partial stasis and consistently generates thrombi within a major vein has been recently established. The Electrolytic Inferior vena cava Model (EIM) is mouse model of DVT that permits thrombus formation in the presence of continuous blood flow. This model allows therapeutic agents to be in contact with the thrombus in a dynamic fashion, and is more sensitive than other models of DVT (1). In addition, this thrombosis model closely simulates clinical situations of thrombus formation and is ideal to study venous endothelial cell activation, leukocyte migration, venous thrombogenesis, and to test therapeutic applications (1). The EIM model is technically simple, easily reproducible, creates consistent thrombi sizes and allows for a large sample (i.e. thrombus and vein wall) which is required for analytical purposes.

Electrolytic Inferior Vena Cava Model EIM of Venous Thrombosis

The electrolytic induction of endothelial activation to the internal surface of the Inferior Vena Cava results in venous type thrombus formation due to endothelial activation and partial blood stasis, two components of Virchow's triad.

Animal models serve a vital role in deep venous thrombosis (DVT) research in order to study thrombus formation, thrombus resolution and to test potential ...

Mouse Complete Stasis Model of Inferior Vena Cava Thrombosis

Venous thromboembolism (VTE) includes both deep vein thrombosis (DVT) and pulmonary embolism (PE). In the United States (U.S.), the high morbidity and mortality rates make VTE a serious health concern 1-2. After heart disease and stroke, VTE is the third most common vascular disease 3. In the U.S. alone, there is an estimated 900,000 people affected each year, with 300,000 deaths occurring annually 3. A reliable in vivo animal model to study the mechanisms of this disease is necessary.
The advantages of using the mouse complete stasis model of inferior vena cava thrombosis are several. The mouse model allows for the administration of very small volumes of limited availability test agents, reducing costs dramatically. Most promising is the potential for mice with gene knockouts that allow specific inflammatory and coagulation factor functions to be delineated. Current molecular assays allow for the quantitation of vein wall, thrombus, whole blood, and plasma for assays. However, a major concern involving this model is the operative size constraints and the friability of the vessels. Also, due to the small IVC sample weight (mean 0.005 grams) it is necessary to increase animal numbers for accurate statistical analysis for tissue, thrombus, and blood assays such as real-time polymerase chain reaction (RT-PCR), western blot, enzyme-linked immunosorbent (ELISA), zymography, vein wall and thrombus cellular analysis, and whole blood and plasma assays 4-8.
The major disadvantage with the stasis model is that the lack of blood flow inhibits the maximal effect of administered systemic therapeutic agents on the thrombus and vein wall.

The mouse complete stasis model of inferior vena cava thrombosis yields quantifiable amounts of vein wall tissue and thrombus. It has proven useful for evaluating interactions between the vein wall and the occlusive thrombus and in assessing the progression from acute to chronic inflammation.

Venous thromboembolism (VTE) includes both deep vein thrombosis (DVT) and pulmonary embolism (PE).  In the United States (U.S.), the high morbidity and ...

Implantation of Inferior Vena Cava Interposition Graft in Mouse Model

Biodegradable scaffolds seeded with bone marrow mononuclear cells (BMCs) are often used for reconstructive surgery to treat congenital cardiac anomalies. The long-term clinical results showed excellent patency rates, however, with significant incidence of stenosis. To investigate the cellular and molecular mechanisms of vascular neotissue formation and prevent stenosis development in tissue engineered vascular grafts (TEVGs), we developed a mouse model of the graft with approximately 1 mm internal diameter. First, the TEVGs were assembled from biodegradable tubular scaffolds fabricated from a polyglycolic acid nonwoven felt mesh coated with &#949;-caprolactone and L-lactide copolymer. The scaffolds were then placed in a lyophilizer, vacuumed for 24 hr, and stored in a desiccator until cell seeding. Second, bone marrow was collected from donor mice and mononuclear cells were isolated by density gradient centrifugation. Third, approximately one million cells were seeded on a scaffold and incubated O/N. Finally, the seeded scaffolds were then implanted as infrarenal vena cava interposition grafts in C57BL/6 mice. The implanted grafts demonstrated excellent patency (&#62;90%) without evidence of thromboembolic complications or aneurysmal formation. This murine model will aid us in understanding and quantifying the cellular and molecular mechanisms of neotissue formation in the TEVG.

To improve our knowledge of cellular and molecular neotissue formation, a murine model of the TEVG was recently developed. The grafts were implanted as infrarenal vena cava interposition grafts in C57BL/6 mice. This model achieves similar results to those achieved in our clinical investigation, but over a far shortened time-course.

Biodegradable scaffolds seeded with bone marrow mononuclear cells (BMCs) are often used for reconstructive surgery to treat congenital cardiac anomalies. ...

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 ...

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.

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, ...

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 ...

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 ...

An Intact Pericardium Ischemic Rodent Model

This protocol has shown that the pericardium and its contents play an essential anti-fibrotic role in the ischemic rodent model (coronary ligation to induce myocardial injury). The majority of pre-clinical myocardial infarction models require the disruption of pericardial integrity with loss of the homeostatic cellular milieu. However, recently a methodology has been developed by us to induce myocardial infarction, which minimizes pericardial damage and retains the heart&#39;s resident immune cell population. An improved cardiac functional recovery in mice with an intact pericardial space following coronary ligation has been observed. This method provides an opportunity to study inflammatory responses in the pericardial space following myocardial infarction. Further development of the labeling techniques can be combined with this model to understand the fate and function of pericardial immune cells in regulating the inflammatory mechanisms that drive remodeling in the heart, including fibrosis.

This protocol outlines the steps for inducing myocardial infarction in mice while preserving the pericardium and its contents.

This protocol has shown that the pericardium and its contents play an essential anti-fibrotic role in the ischemic rodent model (coronary ligation to ...

Image Acquisition Method for the Sonographic Assessment of the Inferior Vena Cava

Over the past several decades, clinicians have incorporated several applications of diagnostic point-of-care ultrasound (POCUS) into medical decision-making. Among the applications of POCUS, imaging the inferior vena cava (IVC) is practiced by a wide variety of specialties, such as nephrology, emergency medicine, internal medicine, critical care, anesthesiology, pulmonology, and cardiology. Although each specialty uses IVC data in slightly different ways, most medical specialties, at minimum, attempt to use IVC data to make predictions about intravascular volume status. While the relationship between IVC sonographic data and intravascular volume status is complex and highly context-dependent, all clinicians should collect the sonographic data in standardized ways to ensure repeatability. This paper describes standardized IVC image acquisition including patient positioning, transducer selection, probe placement, image optimization, and the pitfalls and limitations of IVC sonographic imaging.&#160;This paper also describes the commonly performed anterior IVC long-axis view and three other views of the IVC that can each provide helpful diagnostic information when the anterior long-axis view is difficult to obtain or interpret.

Point-of-care ultrasound evaluation of the inferior vena cava (IVC) is commonly utilized to identify, among other things, the volume status. Imaging should be performed systematically to ensure repeatability. This manuscript reviews the methods and pitfalls of sonographic IVC examination.

Over the past several decades, clinicians have incorporated several applications of diagnostic point-of-care ultrasound (POCUS) into medical ...

Strategies for Efficient Vascular Anastomosis in Mouse Liver Transplantation

Vascular Reconstruction with the Cuff Technique in Mouse Orthotopic Liver Transplantation

Mouse orthotopic liver transplantation is an effective methodology for investigating the underlying mechanisms of liver ischemia and reperfusion injury. However, the technical challenges pose a barrier to utilizing this valuable experimental model and passing on these skills to the next generation. The most challenging aspect of this procedure is vascular reconstruction, including the portal vein (PV), infrahepatic inferior vena cava (IHIVC), and suprahepatic inferior vena cava. The use of plastic cuffs, rather than sutures, allows for smoother PV and IHIVC reconstruction. Vessels are reconstructed by attaching a cuff made from an intravenous catheter to the tip of the graft vessel and interposing the cuff into the recipient vessel. The two most crucial aspects are properly visualizing the inner lumen of the vessel and avoiding the use of excessive force. Our aim is to provide a technical overview of vascular reconstructions using the cuff technique in recipient surgery. These technical tips for the cuff technique are expected to help microsurgeons facilitate vascular reconstruction and advance their research.

Author Spotlight: Exploring Cold Ischemia and Warm Reperfusion Injury in Fatty Liver Transplantation

This protocol provides technical information for vessel reconstruction using the cuff technique in mouse orthotopic liver transplantation.

Mouse orthotopic liver transplantation is an effective methodology for investigating the underlying mechanisms of liver ischemia and reperfusion injury. ...