Name: establishment and evaluation of a porcine vein graft disease model
Uploaded: 2022-07-25T14:00:00.000+00:00
Duration: 8 min 50 s
Description: Watch this Scientific Journal Video about Establishment and Evaluation of a Porcine Vein Graft Disease Model at JoVE.com

The authors thank Guangdong Laboratory Animals Monitoring Institute for technical support, animal care, and sample collection. They also thank Shenzhen Mindray Bio-Medical Electronics Co., Ltd, for technical support in the ultrasonic examination. This work was supported by Guangdong Science and Technology Program, China, and Jinan University Central Universities Basic Scientific Research Business Expenses Project (2017A020215076, 2008A08003, and 21621409).

The procedures for the care and use of laboratory animals were approved by the Institutional Animal Care and Use Committee of the Guangdong Laboratory Animals Monitoring Institute. All experiments were conducted in accordance with the Guide for the Care and Use of Laboratory Animals (8th Ed., 2011, National Research Council, USA). The surgical procedure is shown in Figure 1.
1. Preoperative preparation of animals
<ol>
	<li>Randomly divide 10 3-month-old male minipigs weighing 30-35 kg into the sham group (n = 5) and VGD group (n = 5).</li>
	<li>Evaluate the preoperative and postoperative health conditions of the pigs using the body mass index (BMI). Calculate the BMI as follows: 
	BMI = body weight (kg)/(body length [cm] &#215; body length [cm]) 
	NOTE: Body length is measured from the pig&#39;s nose to the base of the tail.</li>
	<li>Fast the animals for 12 h before surgery to avoid aspiration after anesthesia. Prepare anesthesia appliances and surgical instruments, including an anesthesia machine, gas, anesthetic drugs, an anesthesia pipeline, a special laryngoscope, and surgical instruments, a rib retainer, sutures, a thyroid retractor, surgical forceps, etc. Sterilize all instruments to be used in the surgery.</li>
</ol>
2. Preparing the animals for surgery
<ol>
	<li>Weigh the animals and calculate the anesthetic dose. Administer intramuscularly the anesthetic mixture comprising&#160;2 mg/kg of 1:1 Tiletamine and Zolazepam, 0.2 mg/kg diazepam, and 0.02 mg/kg atropine17.&#160;Use fentanyl (50 mg/kg) for intraoperative pain relief30.</li>
	<li>Ensure that a proper anesthetic plane is achieved and insert an indwelling venous catheter (20G) into the marginal ear vein to establish ear access. Transfer the pig onto the operation table and place it in the supine position. Immobilize the limbs with bandages and elevate the head with a sterile drape. 
	NOTE: The state of anesthesia was monitored by central fixation of the eyeball, miosis, loss of pupillary reflex, and loss of pain reflex.&#160; The heart rate and blood pressure were maintained at a lower level than the baseline. The surgeon should monitor HR, BP, and other parameters under paralysis and increase the anesthetic dose if HR increases &#62; 20% above baseline.</li>
	<li>Expose the epiglottis and glottis using a veterinary laryngoscope. Perform tracheal intubation with a 7.0-7.5Fr tube and connect it to the anesthesia breathing circuit. 
	NOTE: The ventilator is used for continuous positive pressure ventilation with tidal volume 280 mL, inspiratory/expiratory ratio 1:2, respiratory rate 20 times/min, and positive end-expiratory pressure (5 cm H2O).</li>
	<li>Intravenously inject vecuronium bromide (0.1 mg/kg) to relax the muscles during the surgical procedures and use 2% isoflurane to maintain anesthesia at a respiratory rate of 16-20 bpm and a tidal volume of 10 mL/kg. 
	NOTE: Vecuronium is given to ensure adequate depth of anesthesia in paralyzed animals, especially since the dose of induction drug and isoflurane is on the lower end of recommended.</li>
	<li>Use vet ointment on the pig&#39;s eyes to prevent dryness while under anesthesia. Use electric blankets to maintain the pig&#39;s body temperature at 38 &#176;C &#177; 5 &#176;C.</li>
	<li>Use an electrocardiogram to monitor heart rate, blood oxygen levels, and body temperature.</li>
</ol>
3. Surgical procedures
<ol>
	<li>Shave the left chest wall and apply three alternating rounds of 0.7% iodine and 75% alcohol to aseptically prepare the surgical area up to the left mandibular angle, down to the umbilical cord, left to the posterior axillary line, and right to the axillary front. Place a sterile surgical drape around the surgical area.</li>
	<li>Make a 7-10 cm transverse incision with an electric knife in the third left intercostal space and separate the subcutaneous tissues layer by layer (Figure 2A). Remove a 5-6 cm segment of the third rib with bone scissors and expose the internal mammary vein by a retractor after exposing the third rib-sternal joint (Figure 2B).</li>
	<li>Locate the internal mammary vein along with the left internal mammary artery on the left side of the sternum. Perform a blunt dissection of the internal mammary vein with vascular forceps.</li>
	<li>Perform hemostasis by electrocoagulation of the branches of the left internal mammary vein with an electric knife. If hemostasis is incomplete, use cotton thread ligation for hemostasis. Ligate and mark the two ends of the vein while it is being harvested (Figure 2C).</li>
	<li>Prepare heparin normal saline by adding 2 mL of heparin sodium solution and 98 mL of normal saline. After removing the vein, inject heparin normal saline into the vein for pretreatment (Figure 2D). Then, put the vein into normal saline and keep it for backup.</li>
	<li>Make a similar incision as described above and remove the internal mammary vein in the sham group. Open the pericardium, then close the chest wall in the sham group. Use the internal mammary vein of the sham group for pathological control without coronary artery bypass grafting.</li>
	<li>Make a ~7 cm incision with an electric knife on the pericardium to expose the right coronary artery trunk. Suspend the pericardium and sew on the skin on the ipsilateral side with the 1-0 surgical sutures (Figure 2E). Separate the right coronary artery trunk from the surrounding tissues (Figure 2E).</li>
	<li>Bypass the blocking band under the proximal end of the isolated right coronary artery near the aorta with a wire hook and treat the myocardium with three cycles of 2 min ischemia and 5 min reperfusion by tightening and relaxing the blocking band (Figure 2F). Monitor the heart&#39;s electrical activity with the electrocardiogram monitor during the ischemia/reperfusion preconditioning (Figure 2G). 
	NOTE: When the right coronary artery is blocked, the electrocardiogram shows an increased heart rate and ST-segment elevation.</li>
	<li>Tighten the band to block the right coronary blood flow. Cut the epicardium covering the blood vessels. Expose the coronary artery wall, and cut longitudinally with the tip of a surgical blade against the center of the anterior wall of the blood vessels.</li>
	<li>After cutting the lumen, enlarge the incision with scissors and place a coronary shunt. Insert one end of the shunt with a coil into the distal coronary artery through the tear. Shunt the blood in the coronary arteries into the hollow coronary shunt to ensure a clear operative field (Figure 2H).</li>
	<li>Perform an end-to-side continuous suture between the internal mammary vein and the right coronary trunk with the 7-0 polypropylene suture (Figure 2I). In the middle of the ascending aorta, occlude the left anterolateral wall of the ascending aorta with a semi-occlusion clamp.</li>
	<li>Use a surgical blade to make a small incision in the aortic wall where the adventitia has been cut, insert the head end of the sliding shaft at the head end of the punch into the aortic cavity through this incision, contract the sliding shaft outward, and the circular knife above it cuts off a piece of the arterial wall. The tissue block cut out by the punch is about 3 mm in diameter (Figure 2J).</li>
	<li>Pull out the shunt. Perform an end-to-side continuous suture between the internal mammary vein and the the aortic wall with the 6-0 polypropylene suture (Figure 2K). Open the semi-occlusion clamp.</li>
	<li>Record the bypass flow of the right coronary artery trunk proximal to the anastomosis site using ultrasound. Monitor the heart&#39;s electrical activity using the electrocardiogram (Figure 2L).</li>
	<li>Indwell a temporary drainage tube (Fr: 16) into the chest cavity to allow the blood and fluids to drain. Sew the pericardium incision using a 1-0 cotton thread and close the chest layer by layer (from the inside to the outside: Pleura layer, muscle layer, subcutaneous tissue layer, skin layer) while placing penicillin (about 0.5 g) powder onto each layer. Remove the drainage tube after sewing the skin incision using a 1-0 cotton thread.</li>
</ol>
4. Post-surgery care
<ol>
	<li>Remove the endotracheal tube after the animals returned to spontaneous breathing. The anesthesiologist should assess the animal&#8217;s vitals (e.g., respiratory rate, heart rate, oxygen saturation, etc.) and remove the ECG after the animals wake up and return to spontaneous activity. Send the animals back to the feeding room and place the sham animals in another pen in the breeding room. Keep the animals warm with an electric blanket. Observe the animals every hour after surgery (at least 4 times).</li>
	<li>Feed the animal the day after surgery. Add aspirin (200 mg) 2x daily for 7 days to the animal feed to prevent post-operative thrombosis and reduce wound pain. 
	NOTE: Avoid feeding animals on the day of surgery to prevent aspiration.&#160;</li>
	<li>Administer the animal with an intramuscular injection of penicillin 1x daily for 7 consecutive days to prevent post-operative infection (14,000 units per kg).</li>
</ol>
5. Ultrasonic examination
<ol>
	<li>After CABG surgery, use a sterile ultrasonic probe sleeve to wrap the high-frequency linear array probe. Place the probe on the surface of the venous graft.</li>
	<li>Display the outline of the graft in the two-dimensional ultrasound mode, then shift to the color Doppler mode to detect blood flow in the graft.</li>
</ol>
6. Venous graft tissue collection
<ol>
	<li>Collect 10 mL of blood sample from the venous circuit of the ear vein for biochemical testing. (Table 1). Centrifuge the blood sample at 1,000 x g for 5 min and perform biochemical tests with an automatic biochemical analyzer.</li>
	<li>Anesthetize the animal as described earlier. Upon confirmation of anesthesia depth, inject 10% potassium chloride 0.5mL/kg body weight from the ear marginal vein or forelimb vein. Then, make a 10 cm median sternal incision with an electric knife to harvest the vein graft 30 days after surgery. Fix the body position as in step 2.2., and after sterilization and placement of a drape, make a median sternum incision to split the sternum. During the separation, avoid the main blood vessels and the heart, and separate the grafted blood vessels layer by layer.</li>
	<li>Quickly cut off the large blood vessels connecting to the heart, place the heart and ascending aorta on ice chips, and remove the graft vascular bridge, the connected aorta, and the right coronary artery. Rinse all the samples with normal saline at 4 &#176;C.</li>
	<li>Take the entire graft vessel of about 3-4 cm in size, divide it into 4-5 equal parts, and transfer to cryopreservation tubes. Quickly put the tubes into liquid nitrogen to flash freeze and move to a &#8722;80 &#176;C ultra-low temperature freezer for storage.</li>
	<li>For analysis, rinse the graft with ice-cold 0.9% saline and fix it in 4% paraformaldehyde solution. Maintain a ratio of tissue block size to fixative solution of 1:10 and fix the tissue for more than 12 h.</li>
	<li>Stain the sections in 50 mL of aqueous solution of hematoxylin for 3 min. Separate the sections by washing with 50 mL of 0.5% hydrochloric acid ethanol and 50 mL of 0.2% ammonia water for 10 s each.</li>
	<li>Rinse with running water for 1 h and then clean in distilled water by soaking for 3 min. Dehydrate in 70% and 90% ethanol for 10 min each. Place in 50 mL of 0.5% alcohol eosin staining solution for 2-3 min.</li>
	<li>Dehydrate the stained sections with pure ethanol for 10 min and then soak in pure xylene for 10 min to make the samples transparent. Drip the transparent sections with neutral glue and cover with a coverslip. Observe pathological sections under a light microscope at 40x magnification.</li>
</ol>

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The authors have no conflicts of interest to disclose.

In this study, we described in detail the protocol for animal selection, instrument preparation, surgical procedures, and post-operative evaluation when developing a CABG-induced VGD model. We performed ultrasonic examination of the venous graft before and after CABG surgery and histological examination of the graft 30 days after the surgery. The blood flow in the internal mammary vein was normal before the CABG surgery, while retrograde flow was observed in the graft of the internal mammary vein. Compared with the sham ...

Although coronary heart disease mortality has declined significantly in recent years, half of middle-aged adults in the United States develop ischemic heart-related symptoms each year, and one-third of older adults die from coronary heart disease1. Coronary artery bypass grafting (CABG) is an effective surgical modality to improve myocardial ischemia, and more importantly, it is an irreplaceable surgical modality for the treatment of multivessel coronary artery disease2. Over time, however, vascular grafts develop inflammation, intimal hyperplasia, and progressive atherosclerosis, which is known to lead to vein graft failure or vein graft disease (VGD)3. In patients after CABG, if restenosis occurs, only the diseased blood vessel can be replaced in some cases2. Older patients and added comorbidities make redoing coronary artery bypass grafting quite challenging. Delaying or controlling the pathological problems associated with grafted blood vessels is an urgent problem to be solved. Large animal models of CABG-VGD are needed for the investigation of disease mechanisms and the development of therapeutic strategies. Researchers have successfully established animal VGD models in small and large animals such as mice4, rats5, rabbits6, and pigs7. Compared with small animals, large animals such as pigs have anatomical structures and physiological characteristics similar to humans and have longer lifespans8,9. Thus, large animals are more suitable for exploring long-term pathological changes in venous graft disease and for preclinical testing of drugs or devices. We and our collaborating team have successfully applied surgical techniques to establish a porcine heart failure model and described the cardiac pathological changes in this model10.
CABG surgery has been standardized in clinical practice, but when it is applied to the establishment of VGD animal models, the differences between species, the acquisition of animal equipment and facilities, animal surgical operations, and animal feeding and nursing are huge challenges for researchers. As in clinical practice, the approaches for CABG surgery used to establish VGD animal models include midline sternotomy11 and left lateral thoracotomy12. Midline sternotomy is more commonly used13,14. However, this approach has high risks for both humans and animals. In the study reported by Thankam et al., two of the six pigs used for modeling died during surgery15. High model mortality increases study costs and affects the accuracy of results. A study showed earlier that a left chest wall incision was feasible to establish CABG-induced VGD in pigs11. Here, this study aims to describe a step-by-step protocol to establish a reproducible surgery for a CABG-induced VGD model in minipigs and to evaluate the phenotype of this model. The experimental protocol was jointly designed by the cardiac surgery and anesthesia teams. The surgical approach for the left third intercostal space was determined according to the cadavers of other minipigs in the laboratory before surgery, and the anesthesia method was performed according to the method used at the center16. Blood biochemical tests, ultrasonic examination, and histology examination were conducted to evaluate animal models.

<table><tbody><tr><td>Aortic Punch</td><td>Medtronic Inc. , America</td><td>3.0mm, 3.5mm, 4.0mm</td><td>Used for proximal coronary bridge anastomosis</td></tr><tr><td>Automatic biochemical analyzer</td><td>IDEXX Laboratories, Inc. America</td><td>Catalyst One</td><td></td></tr><tr><td>Cardiac coronary artery bypass grafting instrument kit</td><td>LANDANGER, France</td><td></td><td></td></tr><tr><td>Cardiogram monitor</td><td>Shenzhen Mindray Bio-Medical Electronics Co, Ltd</td><td>MEC-1000</td><td></td></tr><tr><td>Coronary Shunt</td><td>AXIUS&amp;nbsp;</td><td>OF-1500, OF-2500, OF-3000</td><td>The product temporarily blocks the coronary artery during arteriotomy to reduce the amount of bleeding in the surgical field and provide blood flow to the distal end during anastomosis.&amp;nbsp; The Axius shunt plug is not an implant and should be removed prior to completion of the anastomosis.&amp;nbsp;&amp;nbsp;</td></tr><tr><td>Defibrillator</td><td>MEDIANA</td><td>Mediana D500</td><td></td></tr><tr><td>Diazepam</td><td>Nanguo pharmaceutical Co. LTD, Guangdong, China</td><td>H37023039&amp;nbsp;</td><td>Narcotic inducer</td></tr><tr><td>Disposable manual electric knife</td><td>Covidien, America</td><td>E2516H</td><td></td></tr><tr><td>Electric negative pressure suction machine</td><td>Shanghai Baojia Medical Instrument Co, Ltd</td><td>YX932D</td><td></td></tr><tr><td>Esmolol</td><td>Guangzhou Wanzheng Pharmaceutical Co. LTD</td><td>H20055990</td><td>Emergency drugs</td></tr><tr><td>Ice machine&amp;nbsp;</td><td>Local suppliers, Guangzhou, China</td><td></td><td></td></tr><tr><td>Lidocaine&amp;nbsp;</td><td>Chengdu First Pharmaceutical Co. LTD</td><td>H51021662</td><td>Emergency drugs</td></tr><tr><td>Luxtec headlight system</td><td>Luxtec, America</td><td>AX-1375-BIF</td><td>Used for lighting fine parts during operation</td></tr><tr><td>Medical operation magnifier (glasses)</td><td>Germany Lista co, LTD</td><td>SuperVu Galilean 3.5&amp;times;</td><td>Used for fine site operation during operation</td></tr><tr><td>Multi-function high-frequency electrotome</td><td>Shanghai Hutong Electronics Co, Ltd</td><td>GD350-B</td><td></td></tr><tr><td>Nitrogen canister</td><td>Local suppliers, Guangzhou, China</td><td></td><td></td></tr><tr><td>Nonabsorbable surgical suture (polypropylene suture)</td><td>Johnson &amp;amp; Johnson, America</td><td>6-0, 7-0</td><td>Used to suture blood vessels.</td></tr><tr><td>Nonabsorbable suture (cotton thread)</td><td>Covidien, America</td><td>1-0</td><td>Used for skin and muscle tissue tugging</td></tr><tr><td>Open heart surgery instrument kit</td><td>Shanghai Medical Instrument (Group) Co., LTD</td><td></td><td></td></tr><tr><td>Propofol injection</td><td>Xi &#039;an Libang Pharmaceutical Co. LTD</td><td>H19990282</td><td>Anesthetic sedative</td></tr><tr><td>Refrigerator</td><td>Local suppliers, Guangzhou, China</td><td></td><td></td></tr><tr><td>Respiratory anesthesia machine for animal</td><td>Shenzhen Reward Life Technology Co, Ltd, China</td><td>R620-S1</td><td></td></tr><tr><td>Semi-occlusion clamp</td><td>Xinhua Surgical Instrument Co., Ltd.</td><td>ZL1701RB</td><td>Temporarily cut off the aortic flow</td></tr><tr><td>vecuronium bromide</td><td>Richter, Hungary&amp;nbsp;</td><td>JX20090127</td><td>Muscle relaxant</td></tr><tr><td>Veterinary ultrasound system&amp;nbsp;</td><td>Royal Philips, Netherlands</td><td>CX50</td><td></td></tr><tr><td>Zoletil</td><td>Virbac, France</td><td>Zoletil 50&amp;nbsp;</td><td>Animal narcotic</td></tr></tbody></table>

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.

BMI and serum biochemical indices 
The BMI between the sham and VGD groups was not significantly different (sham vs. VGD, 22.05 kg/cm2 &#177; 0.46 kg/cm2 vs. 21.14 kg/cm2 &#177; 0.39 kg/cm2, p = 0.46). The serum biochemical results&#160;are listed in Table 1. Statistically significant changes between the groups were found in four biochemical indexes, including aspartate aminotransferase (AST, sham vs. VGD, 25.25 IU/L &#177; 1.88 I...

Watch this Scientific Journal Video about Establishment and Evaluation of a Porcine Vein Graft Disease Model at JoVE.com

Establishment and Evaluation of a Porcine Vein Graft Disease 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 ...

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1.6K Views.  the First Affiliated Hospital of Jinan University. 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.

Video: Establishment and Evaluation of a Porcine Vein Graft Disease Model

A Modified Heterotopic Swine Hind Limb Transplant Model for Translational Vascularized Composite Allotransplantation (VCA) Research

Vascularized Composite Allotransplantation (VCA) such as hand and face transplants represent a viable treatment option for complex musculoskeletal trauma and devastating tissue loss. Despite favorable and highly encouraging early and intermediate functional outcomes, rejection of the highly immunogenic skin component of a VCA and potential adverse effects of chronic multi-drug immunosuppression continue to hamper widespread clinical application of VCA. Therefore, research in this novel field needs to focus on translational studies related to unique immunologic features of VCA and to develop novel immunomodulatory strategies for immunomodulation and tolerance induction following VCA without the need for long term immunosuppression.
This article describes a reliable and reproducible translational large animal model of VCA that is comprised of an osteomyocutaneous flap in a MHC-defined swine heterotopic hind limb allotransplantation. Briefly, a well-vascularized skin paddle is identified in the anteromedial thigh region using near infrared laser angiography. The underlying muscles, knee joint, distal femur, and proximal tibia are harvested on a femoral vascular pedicle. This allograft can be considered both a VCA and a vascularized bone marrow transplant with its unique immune privileged features. The graft is transplanted to a subcutaneous abdominal pocket in the recipient animal with a skin component exteriorized to the dorsolateral region for immune monitoring.
Three surgical teams work simultaneously in a well-coordinated manner to reduce anesthesia and ischemia times, thereby improving efficiency of this model and reducing potential confounders in experimental protocols. This model serves as the groundwork for future therapeutic strategies aimed at reducing and potentially eliminating the need for chronic multi-drug immunosuppression in VCA.

A Modified Heterotopic Swine Hind Limb Transplant Model for Translational Vascularized Composite Allotransplantation VCA Research

Vascularized Composite Allotransplantations (VCA) have become a clinical reality. However, broad clinical application of VCA is limited by chronic multi-drug immunosuppression. The authors present a reliable and reproducible large animal model to translate novel immunomodulatory strategies that can minimize or potentially eliminate the need of immunosuppression in VCA.

Vascularized Composite Allotransplantation (VCA) such as hand and face transplants represent a viable treatment option for complex musculoskeletal trauma ...

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. ...

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.

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. ...

Surgical Angiogenesis in Porcine Tibial Allotransplantation: A New Large Animal Bone Vascularized Composite Allotransplantation Model

Segmental bone loss resulting from trauma, infection malignancy and congenital anomaly remains a major reconstructive challenge. Current therapeutic options have significant risk of failure and substantial morbidity.
Use of bone vascularized composite allotransplantation (VCA) would offer both a close match of resected bone size and shape and the healing and remodeling potential of living bone. At present, life-long drug immunosuppression (IS) is required. Organ toxicity, opportunistic infection and neoplasm risks are of concern to treat such non-lethal indications.
We have previously demonstrated that bone and joint VCA viability may be maintained in rats and rabbits without the need of long-term-immunosuppression by implantation of recipient derived vessels within the VCA. It generates an autogenous, neoangiogenic circulation with measurable flow and active bone remodeling, requiring only 2 weeks of IS. As small animals differ from man substantially in anatomy, bone physiology and immunology, we have developed a porcine bone VCA model to evaluate this technique before clinical application is undertaken. Miniature swine are currently widely used for allotransplantation research, given their immunologic, anatomic, physiologic and size similarities to man. Here, we describe a new porcine orthotopic tibial bone VCA model to test the role of autogenous surgical angiogenesis to maintain VCA viability.
The model reconstructs segmental tibial bone defects using size- and shape-matched allogeneic tibial bone segments, transplanted across a major swine leukocyte antigen (SLA) mismatch in Yucatan miniature swine. Nutrient vessel repair and implantation of recipient derived autogenous vessels into the medullary canal of allogeneic tibial bone segments is performed in combination with simultaneous short-term IS. This permits a neoangiogenic autogenous circulation to develop from the implanted tissue, maintaining flow through the allogeneic nutrient vessels for a short time. Once established, the new autogenous circulation maintains bone viability following cessation of drug therapy and subsequent nutrient vessel thrombosis.

Currently any kind of vascularized composite allotransplantation depends on long-term-immunosuppression, difficult to support for non-life-critical indications. We present a new porcine tibial VCA model that can be used to study bone VCA and demonstrate the use of surgical angiogenesis to maintain bone viability without the need of long-term immune-modulation.

Segmental bone loss resulting from trauma, infection malignancy and congenital anomaly remains a major reconstructive challenge. Current therapeutic ...

A Reliable Porcine Fascio-Cutaneous Flap Model for Vascularized Composite Allografts Bioengineering Studies

Vascularized Composite Allografts (VCA) such as hand, face, or penile transplant represents the cutting-edge treatment for devastating skin defects, failed by the first steps of the reconstructive ladder. Despite promising aesthetic and functional outcomes, the main limiting factor remains the need for a drastically applied lifelong immunosuppression and its well-known medical risks, preventing broader indications. Therefore, lifting the immune barrier in VCA is essential to tip the ethical scale and improve patients&#39; quality of life using the most advanced surgical techniques. De novo creation of a patient-specific graft is the upcoming breakthrough in reconstructive transplantation. Using tissue engineering techniques, VCAs can be freed of donor cells and customized for the recipient through perfusion-decellularization-recellularization. To develop these new technologies, a large-scale animal VCA model is necessary. Hence, swine fascio-cutaneous flaps, composed of skin, fat, fascia, and vessels, represent an ideal model for preliminary studies in VCA. Nevertheless, most VCA models described in the literature include muscle and bone. This work reports&#160;a reliable and reproducible technique for saphenous fascio-cutaneous flap harvest in swine, a practical tool for various research fields, especially vascularized composite tissue engineering.

The present protocol describes the porcine fascio-cutaneous flap model and its potential use in vascularized composite tissue research.

Vascularized Composite Allografts (VCA) such as hand, face, or penile transplant represents the cutting-edge treatment for devastating skin defects, ...

Bioengineering

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, ...

Porcine As a Training Module for Head and Neck Microvascular Reconstruction

Live models that resemble surgical conditions of humans are needed for training free-flap harvesting and anastomosis. Animal models for training purposes have been available for years in many surgical fields. We used the female (because they are easy to handle for the procedure) Yorkshire pigs for the head and neck reconstruction by harvesting the deep inferior epigastric artery perforator or the superior epigastric artery perforator flap. The anastomosis site (neck skin defect or tracheal wall defect) was prepared via the dissection of the common carotid artery and the internal jugular vein, in which 3.5&#215; loupe magnification was used for anastomosis as we use on human cases in real life. This procedure demonstrates a new training method using a reliable learning model and provides a detailed anatomy in a live scenario. We focused on the ischemia time, harvesting, vessel anastomosis, and designing the flap to fit the defect site. This model improves tissue handling and with the use of proper instruments can be repeated many times so that the surgeon is fully confident before starting the surgery on humans.

Here we present a protocol for the use of the pig superior epigastric artery perforator flap as a learning module for head and neck microvascular reconstruction.

Live models that resemble surgical conditions of humans are needed for training free-flap harvesting and anastomosis. Animal models for training purposes ...

A Pre-Clinical Porcine Model of Orthotopic Heart Transplantation

Fifty-years following the first successful report, cardiac transplantation remains the gold-standard treatment for eligible patients with advanced heart failure. Multiple small-animal models of heart transplantation have been used to study the acute and long-term effects of novel therapies. However, few are tested and demonstrated success in clinical trials. It is of critical importance to evaluate new therapies in a clinically relevant large-animal model for efficient and reliable translation of basic studies&#39;&#160;findings. Here, we describe a pre-clinical large-animal (porcine) model of orthotopic heart transplantation that has been firmly established and previously used to investigate novel cardioprotective strategies. This procedure focuses on acute ischemia-reperfusion injury and is a reliable method to investigate novel interventions which have been tested and validated in smaller experimental models, such as the murine model. We demonstrate its usefulness in assessing cardiac performance during the early post-transplantation period and other potential possibilities enabled by the model.

Here, we describe a pre-clinical large-animal (porcine) model of orthotopic heart transplantation that has been firmly established and utilized to investigate novel cardioprotective strategies.

Fifty-years following the first successful report, cardiac transplantation remains the gold-standard treatment for eligible patients with advanced heart ...

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 ...

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 ...