Name: the left pneumonectomy combined with monocrotaline or sugen as a model of pulmonary hypertension in rats
Uploaded: 2019-03-08T14:30:00
Description: Watch this Scientific Journal Video about The Left Pneumonectomy Combined with Monocrotaline or Sugen as a Model of Pulmonary Hypertension in Rats at JoVE.com

This manuscript was supported by NIH grant 7R01 HL083078-10 grants from the American Heart Association AHA-17SDG33370112 and from the National Institutes of Health NIH K01 HL135474 to Y.S. and from the National Institutes of Health R01 HL133554 to L.H.

The procedures described below have been approved by the Institutional Animal Care and Use Committee (IACUC) of the Icahn School of Medicine at Mount Sinai. All rats received humane care in compliance with the Mount Sinai &#8220;Guide for the Care and Use of Laboratory Animals&#8221;.
1. Preparation for Surgery
<ol>
	<li>Autoclave Cooley-Mayo curved scissors (large scissors), straight Iris scissors (small scissors), McPherson-Vannas Iris scissors (back scissors), Wangensteen tissue forceps (...

<ol>
	<li>Leopold, J., Maron, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+Mechanisms+of+Pulmonary+Vascular+Remodeling+in+Pulmonary+Arterial+Hypertension.">Molecular Mechanisms of Pulmonary Vascular Remodeling in Pulmonary Arterial Hypertension.</a> International Journal of Molecular Sciences. 17 (5), 761 (2016).</li><li>Gomez-Arroyo, J. 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=The+monocrotaline+model+of+pulmonary+hypertension+in+perspective.">The monocrotaline model of pulmonary hypertension in perspective.</a> American Journal of Physiology-Lung Cellular and Molecular Physiology. 302 (4), L363-L369 (2012).</li><li>van Albada, M. E., 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+role+of+increased+pulmonary+blood+flow+in+pulmonary+arterial+hypertension.">The role of increased pulmonary blood flow in pulmonary arterial hypertension.</a> European Respiratory Journal. 26 (3), 487-493 (2005).</li><li>Dickinson, M. G., Bartelds, B., Borgdorff, M. A. J., Berger, R. M. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+disturbed+blood+flow+in+the+development+of+pulmonary+arterial+hypertension:+lessons+from+preclinical+animal+models.">The role of disturbed blood flow in the development of pulmonary arterial hypertension: lessons from preclinical animal models.</a> American Journal of Physiology-Lung Cellular and Molecular Physiology. 305 (1), L1-L14 (2013).</li><li>Stenmark, K. R., Meyrick, B., Galie, N., Mooi, W. 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J., 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=Plexiform-like+lesions+and+increased+tissue+factor+expression+in+a+rat+model+of+severe+pulmonary+arterial+hypertension.">Plexiform-like lesions and increased tissue factor expression in a rat model of severe pulmonary arterial hypertension.</a> American Journal of Physiology-Lung Cellular and Molecular Physiology. 293 (3), L583-L590 (2007).</li><li>Samson, N., Paulin, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Epigenetics,+inflammation+and+metabolism+in+right+heart+failure+associated+with+pulmonary+hypertension.">Epigenetics, inflammation and metabolism in right heart failure associated with pulmonary hypertension.</a> Pulmonary Circulation. 7 (3), 572-587 (2017).</li></ol>

In PAH-affected lungs, vascular proliferation with neointimal formation and obliteration of the pulmonary arteries result in severe hemodynamic changes, right ventricular failure and early mortality7,8. The changes to the vessel walls increase resistance to blood flow, increasing arterial and right ventricular pressure. In the early stages of PAH, usually 3 weeks after administering MCT or Sugen, rats developed nonspecific histological changes like medial hypertr...

Pulmonary arterial hypertension (PAH) is a progressive and fatal disease characterized by an increase in pulmonary blood flow, increased vascular resistance, inflammation, and remodeling of small pulmonary blood vessels1. This remodeling usually results in vascular lesions that obstruct and obliterate small pulmonary arteries, causing vasoconstriction and increasing right ventricle afterload2. Few successful pharmacological treatments of PAH exist; as a consequence, PAH-related mortality remains high. Recently, the focus of research on the pathobiology of pulmonary hypertension has moved towards a mechanism of angio-proliferation in which the role of increased pulmonary blood flow is considered as an important trigger in the development of pulmonary vascular remodeling3,4.
Animal models of pulmonary hypertension have provided critical insights that help to explain the pathophysiology of the disease and have served as a platform for drug, cell, gene, and protein delivery. Traditionally, the chronic hypoxia-induced pulmonary hypertension model and the MCT lung injury model have been the main models used to study PAH pathophysiology5. However, they are not sufficient to produce increased pulmonary blood flow and neointimal pattern of remodeling compared to alterations described in human patients. The chronic-hypoxia model in rodents results in thickening of vessel walls with hypoxic vasoconstriction without angio-obliteration of small pulmonary vessels6. Additionally, the hypoxia condition is reversible. Thus, the hypoxia model is also not sufficient to produce severe PAH. The MCT lung injury model does elicit some endothelial dysfunction but the complex vascular obliterative lesions found in humans with severe primary PAH do not develop in the rats2. Additionally, MCT-treated rats tend to die from MCT-induced lung toxicity, veno-occlusive liver disease and myocarditis rather than from PAH2. Finally, the pneumonectomy alone is not sufficient to produce neointimal lesions in the small pulmonary vessels in a short period of time. After the pneumonectomy, there is minimal elevation in pulmonary arterial pressure7. In humans, the pneumonectomy is well tolerated when the contralateral lung is healthy7.
However, the left pneumonectomy procedure combined with MCT or Sugen is advantageous since it mimics increased pulmonary blood flow and results in pulmonary vascular remodeling comparable to severe clinical PAH. The pneumonectomy is performed on the left lung, which has only 1 lobe, rather than on the right, which has four lobes. If the right lung was removed, the animal would be unable to compensate for the respiratory insufficiency. In the pneumonectomy-MCT model, neointimal pattern of remodeling develops in over 90% of operated-animals treated7. Similarly, the combination of Sugen and pneumonectomy results in severe PAH, characterized by angio-obliterative vascular lesions, proliferation, apoptosis, and RV dysfunction8. The left pneumonectomy procedure is also advantageous compared to other surgical procedures to induce PAH. Previously described models in rats to increase pulmonary blood flow to the lungs include the aorto-caval shunt or subclavian-pulmonary artery anastomosis. These models are extremely complicated7,9,10,11. To perform an aorto-caval shunt, the animal&#39;s abdomen has to be opened. The shunt is placed in the abdominal aorta, which increases blood flow to all abdominal organs instead of just the lungs, thus, PAH takes much longer to develop. Additionally, it is difficult to determine the blood flow through the shunt, whereas with the pneumonectomy the blood flow to the remaining lung doubles. The subclavian-pulmonary artery anastomosis also has many complications. The flow of arterial blood into the vein can lead to thrombosis of anastomosis and bleeding. Like the aorto-caval shunt, it is difficult to determine the blood flow through the anastomosis. Furthermore, it is an expensive and difficult technique that requires vascular surgical skills. The unilateral left pneumonectomy doubles blood flow and shear stress in the contralateral lung and, in combination with MCT or Sugen, causes the typical hemodynamic and histopathological findings of PAH which is endothelial cell damage8,12.
The novelty of this manuscript is presented in the very detailed and comprehensive surgical protocol of the left pneumonectomy in rats and in the discussion of the technical and physiological challenges of these models. Because this protocol is not currently available, many investigators believe the model is too difficult use. Investigators who have performed the left pneumonectomy have faced high mortality and morbidity rates associated with the unnecessary loss of animals, compromising scientific assessment. Instead, many will use classical models such as MCT injection, chronic-hypoxia, or just the pneumonectomy to create PAH. However, these models are much less effective than the combination of MCT or Sugen with the left pneumonectomy. The primary purpose of this article is to provide the first detailed and reproducible surgical protocol for the left unilateral pneumonectomy in rats and provide the best surgical model of PAH. Combining this protocol for left unilateral pneumonectomy with MCT or SU5416 will allow investigators to create a far more effective and clinically relevant model of severe PAH to study the pathogenesis of this fatal disease.

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			<td height="22" style="height:22px;width:223px;">Surgical Blade</td>
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			<td style="width:153px;">371215</td>
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			<td style="width:153px;">NDC 10019-360-40</td>
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			<td height="21" style="height:21px;width:223px;">BD Angiocath 16 G</td>
			<td style="width:111px;">BD</td>
			<td style="width:153px;">381157</td>
			<td>intubation tube, chest tube</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:223px;">BD 1 mL Insulin Syringe</td>
			<td style="width:111px;">BD</td>
			<td style="width:153px;">329652</td>
			<td>administer buprinex post-operatively</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:223px;">Biogel Surgeons Surgical Gloves</td>
			<td style="width:111px;">Biogel</td>
			<td style="width:153px;">30460-01</td>
			<td>sterile surgical gloves</td>
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		<tr height="42">
			<td height="42" style="height:42px;width:223px;">Wahl BravMini+ Trimmer</td>
			<td style="width:111px;">Braintree Scientific</td>
			<td style="width:153px;">CLP-41590 P</td>
			<td>shave surgical site</td>
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		<tr height="42">
			<td height="42" style="height:42px;width:223px;">SU5416</td>
			<td style="width:111px;">Cayman Chemical</td>
			<td style="width:153px;">13342</td>
			<td>Sugen&#160;</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:223px;">Fiber Optic Illuminator</td>
			<td style="width:111px;">Cole-Parmer</td>
			<td style="width:153px;">EW-41723-02</td>
			<td>light for intubation</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:223px;">Surgipro II 4-0 Suture</td>
			<td style="width:111px;">Covidien</td>
			<td style="width:153px;">VP831X</td>
			<td>Closing intercostal muscles</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:223px;">Polysorb 5-0 Suture</td>
			<td style="width:111px;">Covidien</td>
			<td style="width:153px;">GL-885</td>
			<td>Closing skin</td>
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		<tr height="42">
			<td height="42" style="height:42px;width:223px;">Medium Slide Top Induction Chamber</td>
			<td style="width:111px;">DRE Veterinary</td>
			<td style="width:153px;">12570</td>
			<td>oxygen &#38; isoflurane delivery</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:223px;">DRE Compact 150 Rodent Anesthesia Machine</td>
			<td style="width:111px;">DRE Veterinary</td>
			<td style="width:153px;">373</td>
			<td>oxygen &#38; isoflurane delivery</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:223px;">Small Vessel Cauterizer Kit</td>
			<td style="width:111px;">Fine Science Tools</td>
			<td style="width:153px;">18000-00</td>
			<td>cauterizer to minimize bleeding</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:223px;">VentElite Small Animal Ventilator</td>
			<td style="width:111px;">Harvard Apparatus</td>
			<td style="width:153px;">55-7040</td>
			<td>ventilator</td>
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		<tr height="42">
			<td height="42" style="height:42px;width:223px;">MouseSTAT Jr</td>
			<td style="width:111px;">Kent Scientific</td>
			<td style="width:153px;">MSTAT-JR</td>
			<td style="width:252px;">pulse oximeter &#38; heart rate monitor</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:223px;">Mouse Paw Pulse Oximeter Sensor</td>
			<td style="width:111px;">Kent Scientific</td>
			<td style="width:153px;">SPO2-MSE</td>
			<td style="width:252px;">pulse oximeter &#38; heart rate paw sensor</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:223px;">PhysioSuite RightTemp</td>
			<td style="width:111px;">Kent Scientific</td>
			<td style="width:153px;">PS-02</td>
			<td>temperature pad</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:223px;">PVP Prep Solution</td>
			<td style="width:111px;">Medline</td>
			<td style="width:153px;">MDS093944</td>
			<td>Cleaning surgical site</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:223px;">Poly-lined Drape</td>
			<td style="width:111px;">Medline</td>
			<td style="width:153px;">NON21002Z</td>
			<td>cover animal</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:223px;">3 mL syringe</td>
			<td style="width:111px;">Medline</td>
			<td style="width:153px;">SYR103010</td>
			<td>administer fluids post-operatively</td>
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		<tr height="83">
			<td height="83" style="height:83px;width:223px;">Microsurgical Kits, Integra&#160;</td>
			<td style="width:111px;">Miltex</td>
			<td style="width:153px;">95042-540</td>
			<td style="width:252px;">surgical tools: plain wire speculum, double-ended probe, McPherson-Vannas Iris scissors straight, straight iris scissors</td>
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		<tr height="42">
			<td height="42" style="height:42px;width:223px;">Hemostatic forceps - Micro-Jacobson-Mosquito</td>
			<td style="width:111px;">Miltex</td>
			<td style="width:153px;">17-2602</td>
			<td>mosquito</td>
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		<tr height="42">
			<td height="42" style="height:42px;width:223px;">Buprenorphrine HCl 0.3 mg/mL</td>
			<td style="width:111px;">Par Pharmaceutical</td>
			<td style="width:153px;">NDC 42023-179-01</td>
			<td>Pain relief</td>
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			<td height="21" style="height:21px;width:223px;">Cooley-Mayo curved scissors</td>
			<td style="width:111px;">Pilling</td>
			<td style="width:153px;">352090</td>
			<td>Large scissors</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:223px;">Gerald Tissue forceps</td>
			<td style="width:111px;">Pilling</td>
			<td style="width:153px;">351900</td>
			<td>forceps</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:223px;">Wangesnsteen Tissue Forceps</td>
			<td style="width:111px;">Pilling</td>
			<td style="width:153px;">342929</td>
			<td>atraumatic forceps</td>
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		<tr height="42">
			<td height="42" style="height:42px;width:223px;">Pilling Thin Vascular Needle Holder</td>
			<td style="width:111px;">Pilling</td>
			<td style="width:153px;">354962DG</td>
			<td>needle holder</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:223px;">Crotaline</td>
			<td style="width:111px;">Sigma-Aldrich</td>
			<td style="width:153px;">C2401-1G</td>
			<td>MCT</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:223px;">Surflash 20 G IV Catheter</td>
			<td style="width:111px;">Terumo</td>
			<td style="width:153px;">SR*FF2051</td>
			<td style="width:252px;">For pressure reading during organ harvest</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:223px;">ADVantage PV System with 1.2 Fr Catheter</td>
			<td style="width:111px;">Transonic Inc</td>
			<td style="width:153px;">ADV500</td>
			<td style="width:252px;">Record pulmonary artery and right ventricle pressure</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:223px;">Medium Hemoclip</td>
			<td style="width:111px;">Weck</td>
			<td style="width:153px;">523700</td>
			<td>ligate vessels</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:223px;">Open Ligating Clip Applicator; Medium, curved</td>
			<td style="width:111px;">Weck Horizon</td>
			<td style="width:153px;">237081</td>
			<td>hemoclip applicator</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:223px;">Surgical Microscope</td>
			<td style="width:111px;">Zeiss OPMI MD</td>
			<td style="width:153px;">1808</td>
			<td>magnification</td>
		</tr>
	</tbody>
</table>

the left pneumonectomy combined with monocrotaline or sugen as a model of pulmonary hypertension in rats

In this protocol, we detail the correct procedural steps and necessary precautions to successfully perform a left pneumonectomy and induce PAH in rats with the additional administration of monocrotaline (MCT) or SU5416 (Sugen). We also compare these two models to other PAH models commonly used in research. In the last few years, the focus of animal PAH models has moved towards studying the mechanism of angioproliferation of plexiform lesions, in which the role of increased pulmonary blood flow is considered as an important trigger in the development of severe pulmonary vascular remodeling. One of the most promising rodent models of increased pulmonary flow is the unilateral left pneumonectomy combined with a "second hit" of MCT or Sugen. The removal of the left lung leads to increased and turbulent pulmonary blood flow and vascular remodeling. Currently, there is no detailed procedure of the pneumonectomy surgery in rats. This article details a step-by-step protocol of the pneumonectomy surgical procedure and post-operative care in male Sprague-Dawley rats. Briefly, the animal is anesthetized and the chest is opened. Once the left pulmonary artery, pulmonary vein, and bronchus are visualized, they are ligated and the left lung is removed. The chest then closed and the animal recovered. Blood is forced to circulate only on the right lung. This increased vascular pressure leads to a progressive remodeling and occlusion of small pulmonary arteries. The second hit of MCT or Sugen is used one week post-surgery to induce endothelial dysfunction. The combination of increased blood flow in the lung and endothelial dysfunction produces severe PAH. The primary limitation of this procedure is that it requires general surgical skills.

According to the accepted classification system, pulmonary hypertension is characterized by a mean pulmonary artery pressure (mPAP) exceeding the upper limits of normal pulmonary artery pressure (i.e., 25 mm Hg). In the pneumonectomy + MCT group, severe PAH developed by day 21 with an increased mPAP (Figure 1). The mPAP is calculated by the formula:
<img alt="Equation" src="/files/ftp_upload/59050/5...

Watch this Scientific Journal Video about The Left Pneumonectomy Combined with Monocrotaline or Sugen as a Model of Pulmonary Hypertension in Rats at JoVE.com

The Left Pneumonectomy Combined with Monocrotaline or Sugen as a Model of Pulmonary Hypertension in Rats

The rodent left pneumonectomy is a valuable technique in pulmonary hypertension research. Here, we present a protocol to describe the rat pneumonectomy procedure and postoperative care to ensure minimal morbidity and mortality.

In this protocol, we detail the correct procedural steps and necessary precautions to successfully perform a left pneumonectomy and induce PAH in rats ...

This protocol is significant because it produces the best possible model for pulmonary arterial hypertension. No other model produces the plexiform lesions found in human PAH patients. The main advantage is that we double the flow of blood in the right lung and pulmonary artery, causing endothelial damage and forcing the lungs to work twice as hard.Our group has developed a highly efficient model of pulmonary arterial hypertension to develop therapeutics. Besides pulmonary artery hypertension, this method could be helpful in regenerative medicine and could give insight to other diseases with increased pulmonary flow like congenital heart defects or post-pneumonectomy patients. For someone who has never performed this technique, my advice is to follow the protocol exactly and to make sure the surgeon can see exactly what they are doing.After anesthetizing the rat with 4%isoflurane, the animal is intubated using a fiber optic gooselight to illuminate the trachea. Insert a 16-gauge catheter into the larynx, and use a cold mirror to observe the condensation of the humidity in the exhaled breath from the catheter to confirm the intubation. Connect the rat to the ventilator and place the rat under the microscope in the right decubitus position on a 37 degree Celsius heating pad.Secure the forelimbs with tape, and use clippers to shave the left thorax from behind the front leg to the end of the ribcage. Clean the exposed skin with three sequential 10%povidone iodine solution and 70%ethanol wipes, and place a pulse-oximeter onto the rat's foot to monitor the heart rate and oxygen saturation throughout the surgery. Now, adjust the microscope and bring the surgical view into focus.Then, place a sterile drape over the rat's body and the instrument tray to create a sterile environment. And finally, place sterile instruments on the sterile instrument tray. To perform a left pneumonectomy, use Cooley-Mayo scissors and Gerald tissue forceps to cut a two to three centimeter hole in the surgical drape, and use a surgical blade to make a two centimeter-long lateral incision in the left thorax.Use Cooley-Mayo scissors to cut each layer of tissue until the ribs and intercostal muscles are exposed. Use a mosquito to make a hole through the muscle of the third intercostal space. Using a double-ended probe, move the lung to visualize the pulmonary artery, and use McPherson-Vannas Iris scissors to open the intercostal muscles to an about one to two centimeter width.Place a small self-retaining retractor into the left pleura to hold the ribs and muscles open, and move the left lung lower in the abdomen to allow access to the pulmonary artery and bronchus. For ligation of the left main bronchus and pulmonary artery, first, load a medium Hemoclip into a ligating clip applicator and use the Wangensteen atraumatic forceps to carefully lift the upper portion of the left lung to expose the pulmonary artery. Close the clip and applicator around the artery, taking care not to close or rupture the left azygos vein.And open the incision further using the tonsil to separate the muscle fibers. After loading another medium Hemoclip into the ligating clip applicator, use the atraumatic forceps and standard tissue forceps to lift the lower portion of the lung out of the incision until the left main bronchus and left pulmonary vein are visualized. Carefully ligate the left main bronchus and pulmonary vein together with the second Hemoclip, and use scissors to remove the lung without cutting or tearing the clip.Then, use a small piece of sterile gauze to absorb any blood and to stem any bleeding. Use the needle holder and a 4-0 prolene suture to close the ribs and intercostal muscles. Before closing the intercostal muscles, insert a 16-gauge catheter into the thoracic cavity away from the surgical incision and into the seventh intercostal space, and immediately remove the needle, leaving the catheter in place.Place a 5-0 suture into the skin and around the chest tube so that when the chest tube is removed, the hole will be tied shut, and tie the sutures to close the ribs. Close the skin and subcutaneous space with a running 5-0 suture, and use a three milliliter syringe to evacuate the air from the pleural cavity through the catheter to restore the normal negative pressure in the thorax. Use a needle holder to immediately clamp the catheter to prevent air from going back into the thoracic cavity.Remove the catheter and tie the suture to close the hole. In the pneumonectomy and monocrotaline group, severe pulmonary hypertension develops by day 21, as evidenced by an increase in mean pulmonary artery pressure compared to control untreated sham animals. In the pneumonectomy plus Sugen group, the mean pulmonary artery pressure is three times higher than in the control group.The right ventricular systolic pressure is also much higher in both the monocrotaline-and Sugen-treated animals, compared to the control group. In hematoxylin and eosin stained normal rat lung tissue sections, spaces between the alveoli and the alveolar structures are apparent, and the vessels are clear and of a normal thickness. In the pulmonary artery hypertension lung, there is evidence of remodeling, thickening of the vessel walls, severe constriction of the vessels, and inflammation and focal pulmonary arteritis.The animal has to compensate for losing a lung, so it's important to be patient during the recovery period. Monitor the vital signs and give additional oxygen or lung volume as necessary. Sugen creates endothelial apoptosis which is clinical relevant sign of pulmonary arterial hypertension.The left pneumonectomy model in rodents has paved the way for scientists to study flow abnormalities and develop novel treatments for pulmonary arterial hypertension. Due to the use of isoflurane, Sugen, and/or MCT in this model, personal protective equipment must be worn at all times.

the-left-pneumonectomy-combined-with-monocrotaline-or-sugen-as-model

Research

JoVE Journal

Medicine

Increasing Pulmonary Artery Pulsatile Flow Improves Hypoxic Pulmonary Hypertension in Piglets

Pulmonary arterial hypertension (PAH) is a disease affecting distal pulmonary arteries (PA). These arteries are deformed, leading to right ventricular failure. Current treatments are limited. Physiologically, pulsatile blood flow is detrimental to the vasculature. In response to sustained pulsatile stress, vessels release nitric oxide (NO) to induce vasodilation for self-protection. Based on this observation, this study developed a protocol to assess whether an artificial pulmonary pulsatile blood flow could induce an NO-dependent decrease in pulmonary artery pressure. One group of piglets was exposed to chronic hypoxia for 3 weeks and compared to a control group of piglets. Once a week, the piglets underwent echocardiography to assess PAH severity. At the end of hypoxia exposure, the piglets were subjected to a pulsatile protocol using a pulsatile catheter. After being anesthetized and prepared for surgery, the jugular vein of the piglet was isolated and the catheter was introduced through the right atrium, the right ventricle and the pulmonary artery, under radioscopic control. Pulmonary artery pressure (PAP) was measured before (T0), immediately after (T1) and 30 min after (T2) the pulsatile protocol. It was demonstrated that this pulsatile protocol is a safe and efficient method of inducing a significant reduction in mean PAP via an NO-dependent mechanism. These data open up new avenues for the clinical management of PAH.

Pulmonary hypertension is associated with a significant reduction in pulmonary artery pulsatility, contractility and elasticity, contributing to an increase in pulmonary artery pressure and pulmonary resistance. Using a hypoxic piglet model, this study demonstrated that improving pulmonary artery plasticity using a newly developed pulsatile catheter improves hypoxic pulmonary hypertension.

Pulmonary arterial hypertension (PAH) is a disease affecting distal pulmonary arteries (PA). These arteries are deformed, leading to right ventricular ...

Scleral Cross-linking Using Riboflavin and Ultraviolet-A Radiation for Prevention of Axial Myopia in a Rabbit Model

Myopic individuals, especially those with severe myopia, are at higher-than-normal risk of cataract, glaucoma, retinal detachment and chorioretinal abnormalities. In addition, pathological myopia is a common irreversible cause of visual impairment and blindness1-3. Our study demonstrates the effect of scleral crosslinking using riboflavin and ultraviolet-A radiation on the development of axial myopia in a rabbit model. The axial length of the eyeball was measured by A-scan ultrasound in New Zealand white rabbits aged 13 days (male and female). The eye then underwent 360&#176; conjunctival peritomy with scleral crosslinking, followed by tarsorrhaphy. Axial elongation was induced in 13 day-old New Zealand rabbits by suturing their right eye eyelids (tarsorrhaphy). The eyes were divided into quadrants, and every quadrant had two scleral irradiation zones, each with an area of 0.2 cm&#178; and a radius of 4 mm. Crosslinking was performed by dropping 0.1% dextran-free riboflavin-5-phosphate onto the irradiation zones 20 sec before ultraviolet-A irradiation and every 20 sec during the 200 sec irradiation time. UVA radiation (370 nm) was applied perpendicular to the sclera at 57 mW/cm&#178; (total UVA light dose, 57 J/cm&#178;). Tarsorrhaphies were removed on day 55, followed by repeated axial length measurements. This study demonstrates that scleral crosslinking with riboflavin and ultraviolet-A radiation effectively prevents occlusion-induced axial elongation in a rabbit model.

We demonstrate the effect of scleral crosslinking with riboflavin and UVA on an axial elongation rabbit eye. Axial elongation was induced in 13 day-old New Zealand rabbits (male and female) by suturing their right eye eyelids (tarsorrhaphy).

Myopic individuals, especially those with severe myopia, are at higher-than-normal risk of cataract, glaucoma, retinal detachment and chorioretinal ...

A Model of Cardiac Remodeling Through Constriction of the Abdominal Aorta in Rats

Heart failure is one of the leading causes of death worldwide. It is a complex clinical syndromethat includes fatigue, dyspnea, exercise intolerance, and fluid retention. Changes in myocardial structure, electrical conduction, and energy metabolism develop with heart failure, leading to contractile dysfunction, increased risk of arrhythmias, and sudden death. Hypertensive heart disease is one of the key contributing factors of cardiac remodeling associated with heart failure. The most commonly-used animal model mimicking hypertensive heart disease is created via surgical interventions, such as by narrowing the aorta. Abdominal aortic constriction is a useful experimental technique to induce a pressure overload, which leads to heart failure. The surgery can be easily performed, without the need for chest opening or mechanical ventilation. Abdominal aortic constriction-induced cardiac pathology progresses gradually, making this model relevant to clinical hypertensive heart failure. Cardiac injury and remodeling can be observed 10 weeks after the surgery. The method described here provides a simple and effective approach to produce a hypertensive heart disease animal model that is suitable for studying disease mechanisms and for testing novel therapeutics.

A rat model of abdominal aortic constriction that induces cardiac hypertrophy and remodeling is described. An efficient, highly-reproducible, and minimally-invasive method is used to provide a simple yet useful platform for research in myocardial hypertrophy and dysfunction.

Heart failure is one of the leading causes of death worldwide. It is a complex clinical syndromethat includes fatigue, dyspnea, exercise intolerance, and ...

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

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

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

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

Murine Echocardiography of Left Atrium, Aorta, and Pulmonary Artery

The present methodology teaches the investigator how to measure and use the LAV as a surrogate of chronic elevations in Left Ventricular diastolic pressure through echocardiography, as well as to obtain measurements of the Aorta and PA diameter in mice.
Mice older than 10 d of age can be analyzed using the present technique. The technique is composed of 3 main steps: set-up, image acquisition, and image analysis. The set-up step consists of getting the mouse anesthetized with 1% isoflurane, shaving it, and taping it in a supine position to a heated EKG board where the image acquisition will take place. The image acquisition step consists of learning to identify the cardiac structures and obtaining all the required images with its correspondent probe and axis in order to be able to calculate volumes and diameters. The image analysis step consists of measuring the previously acquired images with the aid of computer software.
Advantages of the proposed technique include a fast (15 min) procedure that would allow the researcher to evaluate interventions in a non-invasive, non-terminal approach and therefore follow the same mouse over time; each mouse can be used as its own control. This fact plus having the same operator perform all the acquisition and analysis for the entire experiment minimizes the limitation of operator-dependency. The present methodology is useful for mouse researchers in cardiovascular and pulmonary medicine.

The following protocol describes the methodology for the acquisition and analysis of echocardiographic images used to obtain the Left Atrial Volume (LAV), Aorta (Ao) diameter, and Pulmonary Artery (PA) diameter in mice. This technique is a non-invasive, non-terminal procedure that allows assessment of the cardiopulmonary function.

The present methodology teaches the investigator how to measure and use the LAV as a surrogate of chronic elevations in Left Ventricular diastolic ...

Induction and Phenotyping of Acute Right Heart Failure in a Large Animal Model of Chronic Thromboembolic Pulmonary Hypertension

The development of acute right heart failure (ARHF) in the context of chronic pulmonary hypertension (PH) is associated with poor short-term outcomes. The morphological and functional phenotyping of the right ventricle is of particular importance in the context of hemodynamic compromise in patients with ARHF. Here, we describe a method to induce ARHF in a previously described large animal model of chronic PH, and to phenotype, dynamically, right ventricular function using the gold standard method (i.e., pressure-volume PV loops) and with a non-invasive clinically available method (i.e., echocardiography). Chronic PH is first induced in pigs by left pulmonary artery ligation and right lower lobe embolism with biological glue once a week for 5 weeks. After 16 weeks, ARHF is induced by successive volume loading using saline followed by iterative pulmonary embolism until the ratio of the systolic pulmonary pressure over systemic pressure reaches 0.9 or until the systolic systemic pressure decreases below 90 mmHg. Hemodynamics are restored with dobutamine infusion (from 2.5 &#181;g/kg/min to 7.5 &#181;g/kg/min). PV-loops and echocardiography are performed during each condition. Each condition requires around 40 minutes for induction, hemodynamic stabilization and data acquisition. Out of 9 animals, 2 died immediately after pulmonary embolism and 7 completed the protocol, which illustrates the learning curve of the model. The model induced a 3-fold increase in mean pulmonary artery pressure. The PV-loop analysis showed that ventriculo-arterial coupling was preserved after volume loading, decreased after acute pulmonary embolism and was restored with dobutamine. Echocardiographic acquisitions allowed to quantify right ventricular parameters of morphology and function with good quality. We identified right ventricular ischemic lesions in the model. The model can be used to compare different treatments or to validate non-invasive parameters of right ventricular morphology and function in the context of ARHF.

We present a protocol to induce and phenotype an acute right heart failure in a large animal model with chronic pulmonary hypertension. This model can be used to test therapeutic interventions, to develop right heart metrics&#160;or to improve the understanding of acute right heart failure pathophysiology.

The development of acute right heart failure (ARHF) in the context of chronic pulmonary hypertension (PH) is associated with poor short-term outcomes. The ...

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 ...

Induction and Characterization of Pulmonary Hypertension in Mice using the Hypoxia/SU5416 Model

Pulmonary Hypertension (PH) is a pathophysiological condition, defined by a mean pulmonary arterial pressure exceeding 25 mm Hg at rest, as assessed by right heart&#160;catheterization. A broad spectrum of diseases can lead to PH, differing in their etiology, histopathology, clinical presentation, prognosis, and response to&#160;treatment. Despite significant progress in the last years, PH remains an uncured disease. Understanding the underlying mechanisms can pave the way for the development of new therapies. Animal models are important research tools to achieve this goal. Currently, there are several models available for recapitulating PH. This protocol describes a two-hit mouse PH model. The stimuli for PH development are hypoxia and the injection of SU5416, a vascular endothelial growth factor (VEGF) receptor antagonist. Three weeks after initiation of Hypoxia/SU5416, animals develop pulmonary vascular remodeling imitating the histopathological changes observed in human PH (predominantly Group 1). Vascular remodeling in the pulmonary circulation results in the remodeling of the right&#160;ventricle (RV). The procedures for measuring RV pressures (using the open chest method), the morphometrical analyses of the RV (by dissecting and weighing both cardiac ventricles) and the histological assessments of the remodeling (both pulmonary by assessing vascular remodeling and cardiac by assessing RV cardiomyocyte hypertrophy and fibrosis) are described in detail. The advantages of this protocol are the possibility of the application both in wild type and in genetically modified mice, the relatively easy and low-cost implementation, and the quick development of the disease of interest (3 weeks). Limitations of this method are that mice do not develop a severe phenotype and PH is reversible upon return to normoxia. Prevention, as well as therapy studies, can easily be implemented in this model, without the necessity of advanced skills (as opposed to surgical rodent models).

This protocol describes the induction of pulmonary hypertension (PH) in mice based on the exposure to hypoxia and the injection of a VEGF receptor antagonist. The animals develop PH and right ventricular (RV) hypertrophy 3 weeks after the initiation of the protocol. The functional and morphometrical characterization of the model is also presented.

Pulmonary Hypertension (PH) is a pathophysiological condition, defined by a mean pulmonary arterial pressure exceeding 25 mm Hg at rest, as assessed by ...

A Model of Reverse Vascular Remodeling in Pulmonary Hypertension Due to Left Heart Disease by Aortic Debanding in Rats

Pulmonary hypertension due to left heart disease (PH-LHD) is the most common form of PH, yet its pathophysiology is poorly characterized than pulmonary arterial hypertension (PAH). As a result, approved therapeutic interventions for the treatment or prevention of PH-LHD are missing. Medications used to treat PH in PAH patients are not recommended for treatment of PH-LHD, as reduced pulmonary vascular resistance (PVR) and increased pulmonary blood flow in the presence of increased left-sided filling pressures may cause left heart decompensation and pulmonary edema. New strategies need to be developed to reverse PH in LHD patients. In contrast to PAH, PH-LHD develops due to increased mechanical load caused by congestion of blood into the lung circulation during left heart failure. Clinically, mechanical unloading of the left ventricle (LV) by aortic valve replacement in aortic stenosis patients or by implantation of LV assist devices in end-stage heart failure patients normalizes not only pulmonary arterial and right ventricular (RV) pressures but also PVR, thus providing indirect evidence for reverse remodeling in the pulmonary vasculature. Using an established rat model of PH-LHD due to left heart failure triggered by pressure overload with subsequent development of PH, a model is developed to study the molecular and cellular mechanisms of this physiological reverse remodeling process. Specifically, an aortic debanding surgery was performed, which resulted in reverse remodeling of the LV myocardium and its unloading. In parallel, complete normalization of RV systolic pressure and significant but incomplete reversal of RV hypertrophy was detectable. This model may present a valuable tool to study the mechanisms of physiological reverse remodeling in the pulmonary circulation and the RV, aiming to develop therapeutic strategies for treating PH-LHD and other forms of PH.

The present protocol describes a surgical procedure to remove ascending-aortic banding in a rat model of pulmonary hypertension due to left heart disease. This technique studies endogenous mechanisms of reverse remodeling in the pulmonary circulation and the right heart, thus informing strategies to reverse pulmonary hypertension and/or right ventricular dysfunction.

Pulmonary hypertension due to left heart disease (PH-LHD) is the most common form of PH, yet its pathophysiology is poorly characterized than pulmonary ...

Multiple Intravenous Bolus Dosing and Invasive Hemodynamic Assessment in a Hypoxia-Induced Mouse Pulmonary Artery Hypertension Model

Pulmonary arterial hypertension (PAH) is a progressive life-threatening disease, primarily affecting small pulmonary arterioles of the lung. Currently, there is no cure for PAH. It is important to discover new compounds that can be used to treat PAH. The mouse hypoxia-induced PAH model is a widely used model for PAH research. This model recapitulates human clinical manifestations of PAH Group 3 disease and is an important research tool to evaluate the effectiveness of new experimental therapies for PAH. Research using this model often requires the administration of compounds in mice. For a compound that needs to be given directly into the bloodstream, optimizing intravenous (IV) administration is a key part of the experimental procedures. Ideally, the IV injection system should permit multiple injections over a set time course. Although the mouse hypoxia-induced PAH model is very popular in many laboratories, it is technically challenging to perform multiple IV bolus dosing and invasive hemodynamic assessment in this model. In this protocol, we present step-by-step instructions on how to carry out multiple IV bolus dosing via mouse jugular vein and perform arterial and right ventricle catheterization for hemodynamic assessment in mouse hypoxia-induced PAH model.

This protocol provides a step-by-step procedure for executing multiple intravenous bolus dose administration and invasive hemodynamic monitoring in mice. Investigators can use this protocol for future therapeutic compound screening for pulmonary artery hypertension.

Pulmonary arterial hypertension (PAH) is a progressive life-threatening disease, primarily affecting small pulmonary arterioles of the lung. Currently, ...