Name: vein interposition model: a suitable model to study bypass graft patency
Uploaded: 2017-01-15T13:00:00
Description: Watch this Scientific Journal Video about Vein Interposition Model: A Suitable Model to Study Bypass Graft Patency at JoVE.com

The authors thank Christiane Pahrmann for her technical assistance. This study was funded by the Deutsche Stiftung fuer Herzforschung (F/28/14). D.W. was supported by the travel award from the International Society for Heart and Lung Transplantation. T.D. received the Else Kro&#776;ner Excellence Stipend from the Else-Kro&#776;ner-Fresenius-Stiftung (2012_EKES.04). S.S. received research grants from the Deutsche Forschungsgemeinschaft (DFG; DE2133/2-1, T.D.&#160; and SCHR992/3- 1, SCHR992/4-1, S.S.).

Animals received humane care in compliance with the Guide for the Principles of Laboratory Animals, prepared by the Institute of Laboratory Animal Resources and published by the National Institutes of Health. All animal protocols were approved by the responsible local authority (&#34;Amt f&#252;r Gesundheit und Verbraucherschutz, Hansestadt (Office for Health and Consumer Protection) Hamburg&#34;).
1. Animal Care
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This video demonstrates a rat vein interposition model to investigate vein graft loss and to allow for the exploration of the underlying pathological processes and the testing of new drugs or therapeutic options.
Anesthesia is a crucial aspect of surgical procedures. A continuous inhalative anesthesia system is recommended, as this is a safe and easy method, especially during prolonged operations. This can be of great importance during the training phase, when the operation takes more than 1 h...

Coronary artery diseases and their complications are among the leading causes of death worldwide. Current therapeutic strategies focus on re-establishing the blood flow, either by dilating the narrowed vessel or by creating a bypass. Coronary artery bypass grafting (CABG) using vein autografts was first described in 1968 and has been refined over the years. Apart from the revascularization of the left anterior descending coronary artery, saphenous vein conduits are most commonly used1. However, graft patency remains the Achilles heel of saphenous vein grafts (SVG). One year after surgery, graft patency is 85%, dropping to 61% after ten years2,3. Unveiling the pathophysiological mechanisms and causes of SVG patency loss is therefore an important task.
This video demonstrates a rat vein interposition model to investigate vein graft loss. The overall goals of this method are to explore the underlying pathobiological and -physiological processes during disease progression and to develop a suitable model for drug or therapeutic option testing. By transplanting the superficial epigastric vein into the arterial system, this model closely mimics the clinical setting of coronary artery bypass grafting. Surgical trauma, ischemia, and wall stress are important triggers of pathological vascular changes and are imitated in the model described.
Different models and species are available to investigate vein graft patency loss. Large animal models, such as pigs4, sheep5, dogs6, and monkeys7, resemble human vessel and anatomical structures and thus enable complex therapeutic strategies, such as bypass stenting or new surgical techniques, to be tested8. However, special housing, equipment, and staff are required. In addition, high costs and the need for an additional anesthetist during surgery impede their broader application. Small animals, including rats, are easy to handle, do not require special housing, and have manageable costs. Compared to mouse models9,10, rat models have the advantage of better operability and therefore less variability in the outcome. Rats are physiologically and genetically more similar to humans than mice11,12. In addition, most wild-type mice only develop limited myointima13, which make mouse models prone to type II errors. The histology of the main mouse veins, such as the inferior vena cava, only consists of a few cell layers and renders early evaluation difficult13. A further disadvantage is the small amount of tissue available for subsequent analysis after graft recovery.
The model described in this video is reproducible, inexpensive, and easy to perform, and it can be established quickly and reliably. It is especially suitable for evaluating expensive experimental therapeutic agents, such as viral vectors for gene therapy, in an economical fashion.

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			<td height="17" style="height:17px;width:236px;">Rat LEW/Crl</td>
			<td style="width:183px;">Charles River</td>
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			<td height="51" style="height:51px;width:236px;">Rat LEW-Tg(Gt(ROSA)26Sor- 1 
			luc)11Jmsk</td>
			<td style="width:183px;">Institute of laboratory animals, Kyoto University, Japan</td>
			<td style="width:145px;">NBPR rat number 0299</td>
			<td style="width:156px;">http://www.anim.med.kyoto-u.ac.jp/NBR/</td>
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			<td height="17" style="height:17px;">PFA 4%</td>
			<td>Electron Microscopy Sciences</td>
			<td>#157135S</td>
			<td align="right">20%</td>
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			<td height="17" style="height:17px;">microsurgical clamp</td>
			<td>Fine Science Tools</td>
			<td>18055-04</td>
			<td>Micro-Serrefine - 4mm</td>
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			<td>Fine Science Tools</td>
			<td>18056-14</td>
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			<td height="17" style="height:17px;">hair removal creme</td>
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			<td height="17" style="height:17px;">Povidone-Iodine</td>
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			<td height="17" style="height:17px;">10-0 Ethilon suture</td>
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			<td>Ratiopharm</td>
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			<td>Metamizole</td>
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			<td>AstraZeneca</td>
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			<td height="38" style="height:38px;">EVICEL</td>
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			<td>fibrin glue</td>
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			<td height="37" style="height:37px;">NaCl 0,9%</td>
			<td>B.Braun</td>
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			<td height="34" style="height:34px;width:236px;">Vevo 770 high-resolution in vivo micro-imaging system</td>
			<td>VisualSonics</td>
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			<td>duplex sonography</td>
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			<td height="17" style="height:17px;">Ecogel 100 ultrasound gel</td>
			<td>Eco-med</td>
			<td>30GB</td>
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			<td>Biosynth</td>
			<td>L-8220</td>
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			<td height="17" style="height:17px;">PBS pH 7,4</td>
			<td>Gibco</td>
			<td>10010023</td>
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		<tr height="17">
			<td height="17" style="height:17px;">Xenogen Ivis 200</td>
			<td>Perkin Elmer</td>
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			<td>bioluminescence imaging</td>
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		<tr height="17">
			<td height="17" style="height:17px;">Weigerts iron hematoxylin Kit</td>
			<td>Merck</td>
			<td>1.15973.0002</td>
			<td>Trichrome staining</td>
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		<tr height="17">
			<td height="17" style="height:17px;">Resorcine-Fuchsine Weigert</td>
			<td>Waldeck</td>
			<td>2.00E-30</td>
			<td>Trichrome staining</td>
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			<td height="17" style="height:17px;">Acid Fuchsin</td>
			<td>Sigma-Aldrich</td>
			<td>F8129-25G</td>
			<td>Trichrome staining</td>
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			<td height="17" style="height:17px;">Ponceau S solution</td>
			<td>Serva Electrophoresis</td>
			<td>33427</td>
			<td>Trichrome staining</td>
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			<td height="17" style="height:17px;">Azophloxin</td>
			<td>Waldeck</td>
			<td>1B-103</td>
			<td>Trichrome staining</td>
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		<tr height="17">
			<td height="17" style="height:17px;width:236px;">Molybdatophosphoric acid hydrate</td>
			<td>Merck</td>
			<td>1.00532.0100</td>
			<td>Trichrome staining</td>
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		<tr height="17">
			<td height="17" style="height:17px;">Orange G</td>
			<td>Waldeck</td>
			<td>1B-221</td>
			<td>Trichrome staining</td>
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		<tr height="17">
			<td height="17" style="height:17px;">Light Green SF</td>
			<td>Waldeck</td>
			<td>1B-211</td>
			<td>Trichrome staining</td>
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			<td height="17" style="height:17px;">Vitro-Clud</td>
			<td>Langenbrinck</td>
			<td>04-0001</td>
			<td></td>
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			<td height="17" style="height:17px;">Glacial Acetic Acid</td>
			<td>Sigma-Aldrich</td>
			<td align="right">537020</td>
			<td></td>
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			<td height="17" style="height:17px;">37% HCl</td>
			<td>Sigma-Aldrich</td>
			<td>H1758</td>
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			<td height="17" style="height:17px;">Xylene</td>
			<td>Th. Geyer</td>
			<td align="right">3410</td>
			<td></td>
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		<tr height="17">
			<td height="17" style="height:17px;">Paraffin</td>
			<td>Leica biosystems</td>
			<td>REF 39602004</td>
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			<td height="17" style="height:17px;">Ethanol absolute</td>
			<td>Th. Geyer</td>
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			<td></td>
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			<td height="17" style="height:17px;">Ethanol 96%</td>
			<td>Th. Geyer</td>
			<td align="right">2295</td>
			<td></td>
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		<tr height="17">
			<td height="17" style="height:17px;">Ethanol 70%</td>
			<td>Th. Geyer</td>
			<td align="right">2270</td>
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			<td height="17" style="height:17px;">Slide Rack</td>
			<td>Ted Pella</td>
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			<td height="17" style="height:17px;">Bepanthen Eye and Nose ointment</td>
			<td>Bayer</td>
			<td align="right">1578675</td>
			<td>Eye ointment</td>
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vein interposition model: a suitable model to study bypass graft patency

Bypass grafting is an established treatment method for coronary artery disease. Graft patency continues to be the Achilles heel of saphenous vein grafts. Research models for bypass graft failure are essential for a better understanding of pathobiological and pathophysiological processes during graft patency loss. Large animal models, such as pigs or sheep, resemble human anatomical structures but require special facilities and equipment. This video describes a rat vein interposition model to investigate vein graft patency loss. Rats are inexpensive and easy to handle. Compared to mouse models, the convenient size of rats permits better operability and enables a sufficient amount of material to be obtained for further diverse analysis. In brief, the inferior epigastric vein of a donor rat is harvested and used to replace a segment of the femoral artery. Anastomosis is conducted via single stitches and sealed with fibrin glue. Graft patency can be monitored non-invasively using duplex sonography. Myointimal hyperplasia, which is the main cause for graft patency loss, develops progressively over time and can be calculated from histological cross sections.

The rat vein interposition model is suitable to study the development of myointima hyperplasia and vein graft failure. Animals recover well from the surgery and show excellent physical condition post-operation. Figure 1 shows the key surgical steps. After the skin incision along the linea inguinalis, the epigastric superficial vein and femoral artery are identified (Figure 1A). Harvesting of the graft should be performed carefully, without damaging the graft (Figure 1B),...

Watch this Scientific Journal Video about Vein Interposition Model: A Suitable Model to Study Bypass Graft Patency at JoVE.com

Vein Interposition Model: A Suitable Model to Study Bypass Graft Patency

This video demonstrates a model to study the development of myointimal hyperplasia after venous interposition surgery in rats.

Bypass grafting is an established treatment method for coronary artery disease. Graft patency continues to be the Achilles heel of saphenous vein grafts. ...

The overall goal of this procedure is to study bypass graft patency in a rat vein interposition model. This method can help answer key questions in the bypass surgery field, such as underlying path of biological and physiological processes during bypass occlusion. The main advantage of this technique is that the surgical procedure is easy and fast, which can be used to study novel therapeutics and tracts in vivo.Demonstrating the technique will be Grigol Tediashvili, a micro-surgeon from our laboratory. Before the surgery, check for a sufficient depth of anesthesia by pinching the rat's hind feet and verifying an absence of reflexes. Then, apply some vet ointment to the eyes to prevent dryness while under anesthesia.Next, spread the hind legs and fix their position using tape. Then, shave the inguinal hair with a hair trimmer, followed by disinfecting the area widely using povidone-iodine followed by 80%alcohol. Repeat these alternating scrubs a total of three times.Now under a microscope, perform a vertical incision along the linea inguinalis. Next, use two forceps to gently separate the subcutaneous tissues, and expose the superficial epigastric vein up to its origin on the femoral vein. Do this very carefully, as the vein is fragile.Next, stop the blood flow through the superficial epigastric vein using two clamps. Now, harvest a segment of the vein. Carefully lift the isolated vein and cut through the vessel using micro-scissors.Then, place the vein segment on sterile gauze. There, carefully glide a 30-gauge needle into one end and flush the vein with heparin. Then, transfer the vein into 1%lidocaine, and keep it on ice to prevent spasms.Now, euthanize the donor rat by increasing the anesthesia to 5%isoflurane. Next, in preparation for the anastamoses, prepare the recipient rat in the same way as the donor rat up to the shaving step. After two to three minutes of 5%isoflurane, open the donor rat's abdomen along the linea alba, cut through the diaphragm, and remove the heart to stop circulation.Continue preparing the recipient rat for surgery. Shave the medial side of the legs with a hair trimmer and disinfect the skin with three alternating scrubs of povidone-iodine and 80%ethanol. Before proceeding further, perform another toe pinch to monitor the anesthesia.Now, perform a median femoral incision from the knee to the inguinal fold. Under the microscope, use two forceps to separate the femoral artery from its surroundings. Then, use two micro clamps to stop the blood flow, placing the proximal clamp first.Next, cut out a short segment of the clamped femoral artery and discard it. Shorten the remaining arterial stump to leave a gap that is one to two millimeters larger than the vein graft. Then, flush the arterial stump with heparin from a 30-gauge needle.If the adventitia protrudes slightly beyond the vessel stump, use forceps to pull the adventitia slightly over the end of the vessel, and then, remove a piece of adventitia. Now, place the harvested vein segment between the arterial stumps in the correct orientation, and adjust the gap size for a good fit. Now, perform the proximal anastomosis first using 10-0 prolene suture.Start with suturing each lateral side, then add three more sutures to the ventral side. Finish with three stitches on the dorsal side. Next, connect the distal vessels using the same technique, starting with a suture on each lateral side, followed by three sutures on the ventral side, and then finishing on the dorsal side.After completing the anastomoses, load two one-milliliter syringes with the fibrin glue components. Then, carefully lift the graft with forceps, and apply approximately 100 microliters of component one under the graft, followed by 100 microliters of component two. The two components must always be added in the same volumes.Now, place the graft back in its position, and apply 100 microliters of each component over the graft to completely cover the graft and the anastomosis. This prevents anastomotic insufficiency and overdistention of the vein graft. Now, carefully open the clamps starting with the distal clamp.Then, confirm a successful surgery by checking for a visible pulse in the transplanted vein and distal artery of the graft. Before closing the skin, remove any excessive glue that could impede closure. Then, close the skin layers using 5-0 prolene sutures.Before the rat wakes up, inject four to five milligrams of carprofen per kilogram subcutaneously. Keep an eye on the animal until it has regained sufficient consciousness to maintain sternal recumbency. Then, give the rat a home cage without other animals.For the next three days, provide metamizole in the drinking water, and check the rat's recovery daily. Once fully recovered, the rat can be housed with other rats. Animals recover well from the surgery and showed excellent physical condition post-operation.Successful integration of the vein into the femoral artery and graft patency after transplantation was confirmed noninvasively using duplex sonography. By transplanting the vein of a luke-positive rat to a luke-negative rat, bioluminescence imaging was used to monitor the graft's presence. It was found that myointimal hyperplasia develops progressively in the graft over time.Histological staining with Masson's trichrome demonstrates myointimal formation inside the internal elastic lamina. To confirm that the model reproduces the dynamics of myointimal hyperplasia, luminal obliteration was measured. A gradual loss of graft patency was noted from seven days to 28 days post-surgery, which fits the model nicely.Once mastered, this technique can be done in 20 minutes if it is performed properly. Thank you for watching, and good luck with your experiments.

vein-interposition-model-suitable-model-to-study-bypass-graft

Research

JoVE Journal

Medicine

Training a Sophisticated Microsurgical Technique: Interposition of External Jugular Vein Graft in the Common Carotid Artery in Rats

Neointimal hyperplasia is one the primary causes of stenosis in arterialized veins that are of great importance in arterial coronary bypass surgery, in peripheral arterial bypass surgery as well as in arteriovenous fistulas.1-5 The experimental procedure of vein graft interposition in the common carotid artery by using the cuff-technique has been applied in several research projects to examine the aetiology of neointimal hyperplasia and therapeutic options to address it. 6-8 The cuff prevents vessel anastomotic remodeling and induces turbulence within the graft and thereby the development of neointimal hyperplasia.
Using the superior caval vein graft is an established small-animal model for venous arterialization experiment.9-11 This current protocol refers to an established jugular vein graft interposition technique first described by Zou et al., 9 as well as others.12-14 Nevertheless, these cited small animal protocols are complicated.
To simplify the procedure and to minimize the number of experimental animals needed, a detailed operation protocol by video training is presented. This video should help the novice surgeon to learn both the cuff-technique and the vein graft interposition. Hereby, the right external jugular vein was grafted in cuff-technique in the common carotid artery of 21 female Sprague Dawley rats categorized in three equal groups that were sacrificed on day 21, 42 and 84, respectively. Notably, no donor animals were needed, because auto-transplantations were performed. The survival rate was 100 % at the time point of sacrifice. In addition, the graft patency rate was 60 % for the first 10 operated animals and 82 % for the remaining 11 animals. The blood flow at the time of sacrifice was 8&plusmn;3 ml/min. In conclusion, this surgical protocol considerably simplifies, optimizes and standardizes this complicated procedure. It gives novice surgeons easy, step-by-step instruction, explaining possible pitfalls, thereby helping them to gain expertise fast and avoid useless sacrifice of experimental animals.

Neointimal hyperplasia is the primary cause of stenosis in arterialized veins. We propose a new protocol whereby the right external jugular vein is grafted using the cuff technique in the common carotid artery of Sprague Dawley rats. The survival rate was 100 % at the time point of sacrifice.

Neointimal hyperplasia is one the primary causes of stenosis in arterialized veins that are of great importance in arterial coronary bypass surgery, in ...

A Human Ex Vivo Atherosclerotic Plaque Model to Study Lesion Biology

Atherosclerosis is a chronic inflammatory disease of the vasculature. There are various methods to study the inflammatory compound in atherosclerotic lesions. Mouse models are an important tool to investigate inflammatory processes in atherogenesis, but these models suffer from the phenotypic and functional differences between the murine and human immune system. In vitro cell experiments are used to specifically evaluate cell type-dependent changes caused by a substance of interest, but culture-dependent variations and the inability to analyze the influence of specific molecules in the context of the inflammatory compound in atherosclerotic lesions limit the impact of the results. In addition, measuring levels of a molecule of interest in human blood helps to further investigate its clinical relevance, but this represents systemic and not local inflammation. Therefore, we here describe a plaque culture model to study human atherosclerotic lesion biology ex vivo. In short, fresh plaques are obtained from patients undergoing endarterectomy or coronary artery bypass grafting and stored in RPMI medium on ice until usage. The specimens are cut into small pieces followed by random distribution into a 48-well plate, containing RPMI medium in addition to a substance of interest such as cytokines or chemokines alone or in combination for defined periods of time. After incubation, the plaque pieces can be shock frozen for mRNA isolation, embedded in Paraffin or OCT for immunohistochemistry staining or smashed and lysed for western blotting. Furthermore, cells may be isolated from the plaque for flow cytometry analysis. In addition, supernatants can be collected for protein measurement by ELISA. In conclusion, the presented ex vivo model opens the possibility to further study inflammatory lesional biology, which may result in identification of novel disease mechanisms and therapeutic targets.

A Human Ex Vivo Atherosclerotic Plaque Model to Study Lesion Biology

Atherosclerosis is a chronic inflammatory process. This manuscript illustrates an easy to use ex vivo model to investigate fresh carotid or coronary artery plaques. The ex vivo model allows for the investigation of potential substances on the inflammatory milieu in human atherosclerotic lesions and results can be analyzed by various methods.

Atherosclerosis is a chronic inflammatory disease of the vasculature. There are various methods to study the inflammatory compound in atherosclerotic ...

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. ...

Cardiopulmonary Bypass in a Mouse Model: A Novel Approach

As prolonged cardiopulmonary bypass becomes more essential during cardiac interventions, an increasing clinical demand arises for procedure optimization and for minimizing organ damage resulting from prolonged extracorporal circulation. The goal of this paper was to demonstrate a fully functional and clinically relevant model of cardiopulmonary bypass in a mouse. We report on the device design, perfusion circuit optimization, and microsurgical techniques. This model is an acute model, which is not compatible with survival due to the need for multiple blood drawings. Because of the range of tools available for mice (e.g., markers, knockouts, etc.), this model will facilitate investigation into the molecular mechanisms of organ damage and the effect of cardiopulmonary bypass in relation to other comorbidities.

This paper describes how to perform cardiopulmonary bypass in mice. This novel model will facilitate the investigation of the molecular mechanisms involved in organ damage.

As prolonged cardiopulmonary bypass becomes more essential during cardiac interventions, an increasing clinical demand arises for procedure optimization ...

Surgical Swine Model of Chronic Cardiac Ischemia Treated by Off-Pump Coronary Artery Bypass Graft Surgery

Chronic cardiac ischemia that impairs cardiac function, but does not result in infarct, is termed hibernating myocardium (HM). A large clinical subset of coronary artery disease (CAD) patients have HM, which in addition to causing impaired function, puts them at higher risk for arrhythmia and future cardiac events. The standard treatment for this condition is revascularization, but this has been shown to be an imperfect therapy. The majority of pre-clinical cardiac research focuses on infarct models of cardiac ischemia, leaving this subset of chronic ischemia patients largely underserved. To address this gap in research, we have developed a well-characterized and highly reproducible model of hibernating myocardium in swine, as swine are ideal translational models for human heart disease. In addition to creating this unique disease model, we have optimized a clinically relevant treatment model of coronary artery bypass surgery in swine. This allows us to accurately study the effects of bypass surgery on heart disease, as well as investigate additional or alternate therapies. This model surgically induces single vessel stenosis by implanting a constrictor on the left anterior descending (LAD) artery in a young pig. As the pig grows, the constrictor creates a gradual stenosis, resulting in chronic ischemia with impaired regional function, but preserving tissue viability. Following the establishment of the hibernating myocardium phenotype, we perform off-pump coronary artery bypass graft surgery to revascularize the ischemic region, mimicking the gold-standard treatment for patients in the clinic.

This protocol presents a surgical large animal model of chronic, single vessel ischemia that results in regional abnormalities but does not create infarct, known as hibernating myocardium. Following establishment of chronic ischemia, animals are treated with off-pump LIMA-LAD coronary artery bypass graft surgery to revascularize the ischemic tissue.

Chronic cardiac ischemia that impairs cardiac function, but does not result in infarct, is termed hibernating myocardium (HM). A large clinical subset of ...

A Rabbit Model of Durable Transgene Expression in Jugular Vein to Common Carotid Artery Interposition Grafts

Vein graft bypass surgery is a common treatment for occlusive arterial disease; however, long-term success is limited by graft failure due to thrombosis, intimal hyperplasia, and atherosclerosis. The goal of this article is to demonstrate a method for placing bilateral venous interposition grafts in a rabbit, then transducing the grafts with a gene transfer vector that achieves durable transgene expression. The method allows the investigation of the biological roles of genes and their protein products in normal vein graft homeostasis. It also allows the testing of transgenes for the activities that could prevent vein graft failure, e.g., whether the expression of a transgene prevents the neointimal growth, reduces the vascular inflammation, or reduces atherosclerosis in rabbits fed with a high-fat diet. During an initial survival surgery, the segments of right and left external jugular vein are excised and placed bilaterally as reversed end-to-side common carotid artery interposition grafts. During a second survival surgery, performed 28 days later, each of the grafts is isolated from the circulation with vascular clips and the lumens are filled (via an arteriotomy) with a solution containing a helper-dependent adenoviral (HDAd) vector. After a 20-min incubation, the vector solution is aspirated, the arteriotomy is repaired, and flow is restored. The veins are harvested at time points dictated by individual experimental protocols. The 28-day delay between the graft placement and the transduction is necessary to ensure the adaptation of the vein graft to the arterial circulation. This adaptation avoids rapid loss of transgene expression that occurs in vein grafts transduced before or immediately after grafting. The method is unique in its ability to achieve durable, stable transgene expression in grafted veins. Compared to other large animal vein graft models, rabbits have advantages of low cost and easy handling. Compared to rodent vein graft models, rabbits have larger and easier-to-manipulate blood vessels that provide abundant tissue for analysis.

This method describes the placement of interposition vein grafts in rabbits, the transduction of the grafts, and the achievement of durable transgene expression. This allows the investigation of physiological and pathological roles of transgenes and their protein products in grafted veins, and testing of gene therapies for vein graft disease.

Vein graft bypass surgery is a common treatment for occlusive arterial disease; however, long-term success is limited by graft failure due to thrombosis, ...

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 ...

A Rabbit Venous Interposition Model Mimicking Revascularization Surgery using Vein Grafts to Assess Intimal Hyperplasia under Arterial Blood Pressure

Although vein grafts have been commonly used as autologous grafts in revascularization surgeries for ischemic diseases, the long-term patency remains poor because of the acceleration of intimal hyperplasia due to the exposure to arterial blood pressure. The present protocol is designed for the establishment of experimental venous intimal hyperplasia by interposing rabbit jugular veins to the ipsilateral carotid arteries. The protocol does not require surgical procedures deep in the body trunk and the extent of the incision is limited, which is less invasive for the animals, allowing long-term observation after implantation. This simple procedure enables researchers to investigate strategies to attenuate the progression of intimal hyperplasia of the implanted vein grafts. Using this protocol, we reported the effects transduction of microRNA-145 (miR-145), which is known to control the phenotype of vascular smooth muscle cells (VSMCs) from the proliferative to the contractile state, into harvested vein grafts. We confirmed the attenuation of intimal hyperplasia of vein grafts by transducing miR-145 before implantation surgery through the phenotype change of the VSMCs. Here we report a less invasive experimental platform to investigate the strategies that can be used to attenuate intimal hyperplasia of vein grafts in revascularization surgeries.

The present protocol aims to experimentally create venous intimal hyperplasia by subjecting veins to arterial blood pressure for developing strategies to attenuate venous intimal hyperplasia following revascularization surgery using vein grafts.

Although vein grafts have been commonly used as autologous grafts in revascularization surgeries for ischemic diseases, the long-term patency remains poor ...

Establishment and Evaluation of a Porcine Vein Graft Disease Model

Venous graft disease (VGD) is the leading cause of coronary artery bypass graft (CABG) failure. Large animal models of CABG-VGD are needed for the investigation of disease mechanisms and the development of therapeutic strategies. 
To perform the surgery, we enter the cardiac chamber through the third intercostal space and carefully dissect the internal mammary vein and immerse it in normal saline. The right main coronary artery is then treated for ischemia. The target vessel is incised, a shunt plug is placed, and the distal end of the graft vein is anastomosed. The ascending aorta is partially blocked, and the proximal end of the graft vein is anastomosed after perforation. The graft vein is checked for patency, and the proximal right coronary artery is ligated. 
CABG surgery is performed in minipigs to harvest the left internal mammary vein for its use as a vascular graft. Serum biochemical tests are used to evaluate the physiological status of the animals after surgery. Ultrasound examination shows that the proximal, middle, and distal end of the graft vessel are unobstructed. In the surgical model, turbulent blood flow in the graft is observed upon histological examination after the CABG surgery, and venous graft stenosis associated with intimal hyperplasia is observed in the graft. The study here provides detailed surgical procedures for the establishment of a repeatable CABG-induced VGD model.

In this protocol, novel pig vein bypass grafting was performed through a small incision in the left chest wall without cardiopulmonary bypass. A postoperative pathology study was done, which showed intimal thickening.

Venous graft disease (VGD) is the leading cause of coronary artery bypass graft (CABG) failure. Large animal models of CABG-VGD are needed for the ...

Porcine Liver Transplantation Without Veno-Venous Bypass As an Extended Criteria Donor Model

Liver transplantation is regarded as the gold standard for the treatment of a variety of fatal hepatic diseases. However, unsolved issues of chronic graft failure, ongoing organ donor shortages, and the increased use of marginal grafts call for the improvement of current concepts, such as the implementation of organ machine perfusion. In order to evaluate new methods of graft reconditioning and modulation, translational models are required. With respect to anatomical and physiological similarities to humans and recent progress in the field of xenotransplantation, pigs have become the main large animal species used in transplantation models. After the initial introduction of a porcine orthotopic liver transplant model by Garnier et al. in 1965, several modifications have been published over the past 60 years.
Due to specifies-specific anatomical traits, a veno-venous bypass during the anhepatic phase is regarded as a necessity to reduce intestinal congestion and ischemia resulting in hemodynamic instability and perioperative mortality. However, the implementation of a bypass increases the technical and logistical complexity of the procedure. Furthermore, associated complications such as air embolism, hemorrhage, and the need for a simultaneous splenectomy have been reported previously.
In this protocol, we describe a model of porcine orthotopic liver transplantation without the use of a veno-venous bypass. The engraftment of donor livers after static cold storage of 20 h - simulating extended criteria donor conditions - demonstrates that this simplified approach can be performed without significant hemodynamic alterations or intraoperative mortality and with regular uptake of liver function (as defined by bile production and liver-specific CYP1A2 metabolism). The success of this approach is ensured by an optimized surgical technique and a sophisticated anesthesiologic volume and vasopressor management.
This model should be of special interest for workgroups focusing on the immediate postoperative course, ischemia-reperfusion injury, associated immunological mechanisms, and the reconditioning of extended criteria donor organs.

In this protocol, a model of porcine orthotopic liver transplantation after static cold storage of donor organs for 20 h without the use of a veno-venous bypass during engraftment is described. The approach uses a simplified surgical technique with minimization of the anhepatic phase and sophisticated volume and vasopressor management.

Liver transplantation is regarded as the gold standard for the treatment of a variety of fatal hepatic diseases. However, unsolved issues of chronic graft ...