This work was supported by a grant B2021-0991 from the Chonnam National University Hospital Biomedical Research Institute and NRF-2020R1F1A1073921 from the National Research Foundation of Korea

The ethical committee of the Laboratory Animal Research Center of Chonnam National University Hospital (approval no. CNU IACUC - H - 2022-36) approved all the animal experiments. Male Sprague-Dawley rats (350-450 g), used in this study received care in compliance with the guidelines for the care and use of the laboratory animals. The rats were housed in temperature-controlled rooms with a 12 h light-dark cycle, with standard food and water available.
1. Preparation
<p class=...

<ol>
	<li>Langmuur, S. J. 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=Normothermic+ex-situ+heart+perfusion+with+the+organ+care+system+for+cardiac+transplantation:+A+meta-analysis.">Normothermic ex-situ heart perfusion with the organ care system for cardiac transplantation: A meta-analysis.</a> Transplantation. 106 (9), 1745-1753 (2022).</li><li>Ardehali, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ex-vivo+perfusion+of+donor+hearts+for+human+heart+transplantation+(PROCEED+II):+a+prospective,+open-label,+multicentre,+randomized+non-inferiority+trial.">Ex-vivo perfusion of donor hearts for human heart transplantation (PROCEED II): a prospective, open-label, multicentre, randomized non-inferiority trial.</a> Lancet. 385 (9987), 2577-2584 (2015).</li><li>Dang Van, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ex+vivo+perfusion+of+the+donor+heart:+Preliminary+experience+in+high-risk+transplantations.">Ex vivo perfusion of the donor heart: Preliminary experience in high-risk transplantations.</a> Archives of Cardiovascular Diseases. 114 (11), 715-726 (2021).</li><li>Zhou, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Donor+heart+preservation+with+hypoxic-conditioned+medium-derived+from+bone+marrow+mesenchymal+stem+cells+improves+cardiac+function+in+a+heart+transplantation+model.">Donor heart preservation with hypoxic-conditioned medium-derived from bone marrow mesenchymal stem cells improves cardiac function in a heart transplantation model.</a> Stem Cell Research and Therapy. 12 (1), 5f6 (2021).</li><li>Messer, S., Large, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Resuscitating+heart+transplantation:+the+donation+after+circulatory+determined+death+donor.European.">Resuscitating heart transplantation: the donation after circulatory determined death donor.European.</a> Journal of Cardio-Thoracic Surgery. 49 (1), 1-4 (2016).</li><li>Trahanas, J. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Achieving+12+hour+normothermic+ex+situ+heart+perfusion:+an+experience+of+40+porcine+hearts.">Achieving 12 hour normothermic ex situ heart perfusion: an experience of 40 porcine hearts.</a> ASAIO Journal. 62 (4), 470-476 (2016).</li><li>Yang, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Keeping+donor+hearts+in+completely+beating+status+with+normothermicblood+perfusion+for+transplants.">Keeping donor hearts in completely beating status with normothermicblood perfusion for transplants.</a> The Annals of Thoracic Surgery. 95 (6), 2028-2034 (2013).</li><li>Van Caenegem, O., 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=Hypothermic+continuous+machine+perfusion+enables+preservation+of+energy+charge+and+functional+recovery+of+heart+grafts+in+an+ex+vivo+model+of+donation+following+circulatory+death.">Hypothermic continuous machine perfusion enables preservation of energy charge and functional recovery of heart grafts in an ex vivo model of donation following circulatory death.</a> European Journal of Cardiothoracic Surgery. 49 (5), 1348-1353 (2016).</li><li>Lu, 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=Normothermic+ex+vivo+heart+perfusion+combined+with+melatonin+enhances+myocardial+protection+in+rat+donation+after+circulatory+death+hearts+via+inhibiting+NLRP3+inflammasome-mediated+pyroptosis.">Normothermic ex vivo heart perfusion combined with melatonin enhances myocardial protection in rat donation after circulatory death hearts via inhibiting NLRP3 inflammasome-mediated pyroptosis.</a> Frontiers in Cell and Developmental Biology. 9, 733183 (2021).</li><li>Pinnelas, R., Kobashigawa, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ex+vivo+normothermic+perfusion+in+heart+transplantation:+a+review+of+the+TransMedics+Organ+Care+System.">Ex vivo normothermic perfusion in heart transplantation: a review of the TransMedics Organ Care System.</a> Future Cardiology. 18 (1), 5-15 (2022).</li><li>Fuchs, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Does+the+heart+transplant+have+a+future.">Does the heart transplant have a future.</a> European Journal of Cardiothoracic Surgery. 55, i38-i48 (2019).</li><li>Pahuja, M., Case, B. C., Molina, E. J., Waksman, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Overview+of+the+FDA's+circulatory+system+devices+panel+virtual+meeting+on+the+TransMedics+Organ+Care+System+(OCS)+Heart+-+portable+extracorporeal+heart+perfusion+and+monitoring+system.">Overview of the FDA's circulatory system devices panel virtual meeting on the TransMedics Organ Care System (OCS) Heart - portable extracorporeal heart perfusion and monitoring system.</a> American Heart Journal. 247, 90-99 (2022).</li><li>Jawitz, O. K., Devore, A. D., Patel, C. B., Bryner, B. S., Schroder, J. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Expanding+the+donor+pool:+quantifying+the+potential+impact+of+a+portable+organ-care+system+for+expanded+criteria+heart+donation.">Expanding the donor pool: quantifying the potential impact of a portable organ-care system for expanded criteria heart donation.</a> Journal of Cardiac Failure. 27 (12), 1462-1465 (2021).</li><li>van Suylen, V., 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=Ex+situ+perfusion+of+hearts+donated+after+euthanasia:+a+promising+contribution+to+heart+transplantation.">Ex situ perfusion of hearts donated after euthanasia: a promising contribution to heart transplantation.</a> Transplantation Direct. 7 (3), e676 (2021).</li><li>Westhofen, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+heterotopic+heart+transplantation+in+mice+as+a+small+animal+model+to+study+mechanical+unloading+-+Establishment+of+the+procedure,+perioperative+management+and+postoperative+scoring.">The heterotopic heart transplantation in mice as a small animal model to study mechanical unloading - Establishment of the procedure, perioperative management and postoperative scoring.</a> PLoS One. 14 (4), e0214513 (2019).</li><li>Qin, G., Jernryd, T., Sjoberg, S., Steen, S., Nilsson, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Machine+perfusion+for+human+heart+preservation:+A+systematic+review.">Machine perfusion for human heart preservation: A systematic review.</a> Transplant International. 35, 10258 (2022).</li><li>Dang Van, S., Brunet, D., Akamkam, A., Decante, B., Guihaire, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+assessment+of+the+donor+heart+during+ex+situ+perfusion:+insights+from+pressure-volume+loops+and+surface+echocardiography.">Functional assessment of the donor heart during ex situ perfusion: insights from pressure-volume loops and surface echocardiography.</a> Journal of Visual Experiments. (188), e63945 (2022).</li><li>Fu, X., Segiser, A., Carrel, T. P., Tevaearai Stahel, H. T., Most, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rat+heterotopic+heart+transplantation+model+to+investigate+unloading-induced+myocardial+remodeling.">Rat heterotopic heart transplantation model to investigate unloading-induced myocardial remodeling.</a> Frontiers in Cardiovascular Medicine. 3, 34 (2016).</li><li>Niimi, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+technique+for+heterotopic+cardiac+transplantation+in+mice:+experience+of+3000+operations+by+one+surgeon.">The technique for heterotopic cardiac transplantation in mice: experience of 3000 operations by one surgeon.</a> The Journal of Heart and Lung Transplantation. 20 (10), 1123-1128 (2001).</li><li>Qi, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+evaluation+of+constant+coronary+artery+flow+versus+constant+coronary+perfusion+pressure+during+normothermic+ex-situ+heart+perfusion.">The evaluation of constant coronary artery flow versus constant coronary perfusion pressure during normothermic ex-situ heart perfusion.</a> The Journal of Heart and Lung Transplantation. 41 (12), 1738-1750 (2022).</li><li>Okahara, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+blood+viscosity+estimation+method+based+on+pressure-flow+characteristics+of+an+oxygenator+during+cardiopulmonary+bypass.">A novel blood viscosity estimation method based on pressure-flow characteristics of an oxygenator during cardiopulmonary bypass.</a> Artificial Organs. 41 (3), 262-266 (2017).</li><li>Quader, M., Torrado, J. F., Mangino, M. J., Toldo, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Temperature+and+flow+rate+limit+the+optimal+ex-vivo+perfusion+of+the+heart+-+an+experimental+study.">Temperature and flow rate limit the optimal ex-vivo perfusion of the heart - an experimental study.</a> Journal of Cardiothoracic Surgery. 15 (1), 180 (2020).</li></ol>

The authors have no conflicts of interest.

Our focus in establishing this model was to replicate normothermic human heart transplantation. Non-ejecting models are the commonly preferred technique for preserving the donor heart in an ex situ environment16. While ejecting models offer many advantages in assessing cardiac function during ex situ perfusion17, they are not suitable for heterotopic transplantation models. In heterotopic transplantation, the implanted donor heart needs to overcome systoli...

An erratum was issued for:&#160;<a href="https://www.jove.com/t/64954">Rat Model of Normothermic Ex-Situ Perfused Heterotopic Heart Transplantation</a>. The Protocol section was updated.
Section 4 of the Protocol was updated from:
4. Implantation
<ol>
	<li>Preparation of recipient
	<ol>
		<li>Begin the recipient preparation 30 min before the cessation of ex situ perfusion.</li>
		<li>Anesthetize the recipient animal using the same method as mentioned in step 2.2.</li>
		<li>Place the rat in a supine position on the heating pad and insert the temperature probe into the rectum to maintain the body temperature at 37 &#176;C.</li>
		<li>Apply eye lubricant, shave the pubic to the epigastric area, and cleanse the area with an iodine-based scrub and 70% alcohol.</li>
	</ol>
	</li>
	<li>Medications
	<ol>
		<li>Inject 2 mL of warm saline subcutaneously to compensate for the fluid lost during the surgery. Inject 200 IU of heparin subcutaneously.</li>
		<li>Administer antibiotic prophylaxis by injecting 10 mg/kg cefazolin dissolved in 0.3 mL of saline subcutaneously or intramuscularly.</li>
		<li>Administer pain control by injecting 20 mg/kg of diclofenac subcutaneously.</li>
	</ol>
	</li>
	<li>Perform the mid-line laparotomy and insert a retractor to widen the abdominal cavity. Mobilize the abdominal organs to the left side of the recipient using cotton swabs to make space for the procedure.</li>
	<li>Prevent dehydration by wrapping the abdominal organs with warm and wet gauze. Intermittingly spread warm saline with a 50 mL syringe during the surgery.</li>
	<li>Utilizing a surgical microscope with a 10x magnification, mobilize the duodenum and proximal jejunum by blunt dissection with cotton swabs to expose the Abd. A. and IVC. Prepare the Abd. A and IVC for anastomosis and systematically implant the donor heart, in accordance with Figure 3 or previously documented methods15. 
	NOTE: Do not separate the Abd. A. and IVC.
	<ol>
		<li>Assuming vascular anastomosis to be placed infrarenal, prepare a sufficient portion of the aorta and IVC for clamping.</li>
		<li>Perform blunt preparation using cotton swabs or sharp-serrated forceps to remove the fats and fascia around the vessels.</li>
		<li>Place 5-0 silk ligatures to the mesenteric branches and both the cranial and caudal sides of the major vessels. Elevate the abdominal vessels and coagulate or ligate the lumbar branches with 5-0 silk sutures. Remember to spare the testicular arteries and veins and do not clamp them.</li>
		<li>Use ligatures to lift the vessels and position the micro-clamps to the mesenteric branches, caudal, and cranial sides of the major vessels to stop the blood flow at the anastomosis site. Be sure to switch off the heating pad before placing the clamps, as excess heating can exacerbate limb ischemia.</li>
		<li>Puncture the aorta using a 27 G needle and elongate the incision with micro scissors to a length equal to or slightly larger than the opening of the donor ascending aorta (Asc. A), which is approximately 5 mm.</li>
		<li>Make a longitudinal incision on the IVC in the same way as the aortotomy, but make it 3 mm closer to the caudal side compared to the aorta incision.</li>
		<li>Starting the anastomoses, placed the donor heart on the right side of the recipient&#39;s abdomen and attach the donor Asc. A to the recipient&#39;s Abd. A with one simple interrupted stitch (9-0 polypropylene) at the cranial corner of the longitudinal incision.</li>
		<li>Move the heart to the left side of the recipient abdomen and perform anastomosis of the donor&#39;s Asc. A with the recipient&#39;s Abd. A using a running 9-0 polypropylene suture.</li>
		<li>Fixate the donor pulmonary artery to the IVC with two interrupted sutures (9-0 polypropylene) at the caudal and cranial corners of the longitudinal incision.</li>
		<li>Perform the first half of the venous anastomosis from the intraluminal side of the vessel and complete the second half from the extraluminal side of the vessel. Before tightening the knots, flush the field with saline to prevent air embolism.</li>
	</ol>
	</li>
	<li>De-airing and de-clamping
	<ol>
		<li>Remove the mesenteric vein clamp first after completing the anastomosis to allow the right side of the heart to fill with venous blood.</li>
		<li>Remove the air in the coronary circuit and Asc. A. by applying retrograde coronary perfusion for several seconds.</li>
		<li>Place a piece of gauze on both sides of the vessels and remove the caudal clamp and the cranial clamp.</li>
		<li>Apply gentle compression with cotton swabs for 1-2 min. After ensuring adequate hemostasis, remove the swabs and wash the anastomoses with warm saline. 
		NOTE: The heart should begin beating within the first minute of reperfusion. If the recipient rat&#39;s body temperature is below 35 &#176;C, the heart rhythm will normalize after the temperature reaches 36 &#176;C.</li>
	</ol>
	</li>
	<li>Replace the abdominal organs in a meander-like manner and close the layers of the abdominal incision using continuous 5-0 polypropylene sutures.</li>
</ol>
to:
4. Implantation
<ol>
	<li>Preparation of recipient
	<ol>
		<li>Begin the recipient preparation 30 min before the cessation of ex situ perfusion.</li>
		<li>Anesthetize the recipient animal using the same method as mentioned in step 2.2.</li>
		<li>Place the rat in a supine position on the heating pad and insert the temperature probe into the rectum to maintain the body temperature at 37 &#176;C.</li>
		<li>Apply eye lubricant, shave the pubic to the epigastric area, and cleanse the area with an iodine-based scrub and 70% alcohol.</li>
	</ol>
	</li>
	<li>Medications
	<ol>
		<li>Inject 2 mL of warm saline subcutaneously to compensate for the fluid lost during the surgery. Inject 200 IU of heparin subcutaneously.</li>
		<li>Administer antibiotic prophylaxis by injecting 10 mg/kg cefazolin dissolved in 0.3 mL of saline subcutaneously or intramuscularly.</li>
		<li>Administer pain control by injecting 20 mg/kg of diclofenac subcutaneously.</li>
	</ol>
	</li>
	<li>Perform the mid-line laparotomy and insert a retractor to widen the abdominal cavity. Mobilize the abdominal organs to the left side of the recipient using cotton swabs to make space for the procedure.</li>
	<li>Prevent dehydration by wrapping the abdominal organs with warm and wet gauze. Intermittingly spread warm saline with a 50 mL syringe during the surgery.</li>
	<li>Utilizing a surgical microscope with a 10x magnification, mobilize the duodenum and proximal jejunum by blunt dissection with cotton swabs to expose the Abd. A. and IVC. Prepare the Abd. A and IVC for anastomosis and systematically implant the donor heart, in accordance with Figure 3 or previously documented methods15. 
	NOTE: Do not separate the Abd. A. and IVC.
	<ol>
		<li>Assuming vascular anastomosis to be placed infrarenal, prepare a sufficient portion of the aorta and IVC for clamping.</li>
		<li>Perform blunt preparation using cotton swabs or sharp-serrated forceps to remove the fats and fascia around the vessels.</li>
		<li>Place 5-0 silk ligatures to the mesenteric branches and both the cranial and caudal sides of the major vessels. Elevate the abdominal vessels and coagulate or ligate the lumbar branches with 5-0 silk sutures. Remember to spare the testicular arteries and veins and do not clamp them.</li>
		<li>Use ligatures to lift the vessels and position the micro-clamps to the mesenteric branches, caudal, and cranial sides of the major vessels to stop the blood flow at the anastomosis site. Switch off the heating pad before placing the clamps, as excess heating can exacerbate limb ischemia. Ensure to switch on the heating pad after de-clamping the vessels to avoid hypothermia.</li>
		<li>Puncture the aorta using a 27 G needle and elongate the incision with micro scissors to a length equal to or slightly larger than the opening of the donor ascending aorta (Asc. A), which is approximately 5 mm.</li>
		<li>Make a longitudinal incision on the IVC in the same way as the aortotomy, but make it 3 mm closer to the caudal side compared to the aorta incision.</li>
		<li>Starting the anastomoses, placed the donor heart on the right side of the recipient&#39;s abdomen and attach the donor Asc. A to the recipient&#39;s Abd. A with one simple interrupted stitch (9-0 polypropylene) at the cranial corner of the longitudinal incision.</li>
		<li>Move the heart to the left side of the recipient abdomen and perform anastomosis of the donor&#39;s Asc. A with the recipient&#39;s Abd. A using a running 9-0 polypropylene suture.</li>
		<li>Fixate the donor pulmonary artery to the IVC with two interrupted sutures (9-0 polypropylene) at the caudal and cranial corners of the longitudinal incision.</li>
		<li>Perform the first half of the venous anastomosis from the intraluminal side of the vessel and complete the second half from the extraluminal side of the vessel. Before tightening the knots, flush the field with saline to prevent air embolism.</li>
	</ol>
	</li>
	<li>De-airing and de-clamping
	<ol>
		<li>Remove the mesenteric vein clamp first after completing the anastomosis to allow the right side of the heart to fill with venous blood.</li>
		<li>Remove the air in the coronary circuit and Asc. A. by applying retrograde coronary perfusion for several seconds.</li>
		<li>Place a piece of gauze on both sides of the vessels and remove the caudal clamp and the cranial clamp.</li>
		<li>Apply gentle compression with cotton swabs for 1-2 min. After ensuring adequate hemostasis, remove the swabs and wash the anastomoses with warm saline. 
		NOTE: The heart should begin beating within the first minute of reperfusion. If the recipient rat&#39;s body temperature is below 35 &#176;C, the heart rhythm will normalize after the temperature reaches 36 &#176;C.</li>
	</ol>
	</li>
	<li>Replace the abdominal organs in a meander-like manner and close the layers of the abdominal incision using continuous 5-0 polypropylene sutures.</li>
	<li>After the surgery, place the anesthetized animal on a clean area over a heating pad until the body temperature reaches 37&#176;C.&#160; 
	NOTE: Do not initiate the postoperative examinations till the body temperature reaches 37&#176;C. Maintain anesthesia at 2-2.5% isoflurane until the end of the experiments.</li>
	<li>Monitor ECG of the transplanted donor heart for 3 h. Then, excise the heart under deep anesthesia for histological studies. 
	NOTE: Confirm anesthesia depth via lack of pedal reflex before excising the heart. The surgical procedure and the ECG monitoring take less than 6 h. Diclofenac, administered perioperatively (step 4.2.3.), enables pain management for the entire duration of this procedure. The analgesia regimen can be adjusted per the institutional animal use guidelines.</li>
</ol>

An erratum was issued for:&#160;<a href="https://www.jove.com/t/64954">Rat Model of Normothermic Ex-Situ Perfused Heterotopic Heart Transplantation</a>. The Protocol section was updated.

Erratum: Rat Model of Normothermic Ex-Situ Perfused Heterotopic Heart Transplantation

Heart transplantation remains the sole viable therapy for refractory heart failure1,2,3,4. Despite a steady rise in the number of patients in need of heart transplantation, a proportional increase in the availability of donor organs has not been observed5. To address this issue, novel approaches for preserving donor hearts have been developed with the goal of improving the challenges and increasing the availability of donors6,7,8,9.
Normothermic ex situ heart perfusion (NESHP) using organ care system (OCS) machines has emerged as a clinical intervention1,3. This technique has been deemed a suitable alternative to the conventional static cold storage (SCS) method2,9. NESHP effectively reduces the duration of cold ischemia, diminishes metabolic demand, and facilitates optimal nutritional supply and oxygenation during the transportation of donor organs10,11. Despite the clear potential of this method to improve donor organ preservation, its clinical application and further investigation have been constrained by high costs. Therefore, preclinical animal models of NESHP are crucial for identifying key technical challenges associated with this technique12,13. Pigs and rats are the preferred animal models for preclinical studies due to their ischemic tolerance9. Although the porcine model is ideal for basic and translational research, it is limited by its high cost and the intensive labor required for care and maintenance. In contrast, rat models are less expensive and easier to handle14.
In this study, we introduce a simplified rat model of NESHP, followed by heterotopic heart transplantation, to evaluate the impact of the preservation technique on graft condition post-implantation. This model is straightforward, cost-effective, and can be executed by a single experimenter. Figure 1 shows the schematics of the procedure.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>AES active evacuation system</td>
			<td>Smiths medical</td>
			<td>PC-6769-51A</td>
			<td>Utilize CO2 and excess isoflurane</td>
		</tr>
		<tr>
			<td>Anesthesia machine</td>
			<td>Smiths medical</td>
			<td>PC-8801-01A</td>
			<td>Mixes isoflurane and oxyegn and delivers to animal</td>
		</tr>
		<tr>
			<td>B20 patient monitor</td>
			<td>GE medical systems</td>
			<td>B20</td>
			<td>to observe mean aortic pressure and temperature</td>
		</tr>
		<tr>
			<td>Homeothermic Monitoring System</td>
			<td>Harvard apparatus</td>
			<td>55-7020</td>
			<td>To monitor and maintain animal&#39;s temperature</td>
		</tr>
		<tr>
			<td>Micro-1 Rat oxygenator</td>
			<td>Dongguan Kewei medical instruments</td>
			<td>Micro-MO</td>
			<td>For gas exchange in the langendorff circuit</td>
		</tr>
		<tr>
			<td>Micropuncture introducer Set</td>
			<td>COOK medical</td>
			<td>G48007</td>
			<td>for delivering cardioplegic solution to the arch through the abdominal aorta</td>
		</tr>
		<tr>
			<td>Microscope</td>
			<td>Amscope</td>
			<td>MU1403</td>
			<td>For zooming surgical field (Recipient)</td>
		</tr>
		<tr>
			<td>Surgical loupe</td>
			<td>SurgiTel</td>
			<td>L2S09</td>
			<td>For zooming surgical field (Donor)</td>
		</tr>
		<tr>
			<td>Syringe pump</td>
			<td>AMP all</td>
			<td>SP-8800</td>
			<td>To deliver cardioplegic solution</td>
		</tr>
		<tr>
			<td>Transonic flow sensor</td>
			<td>Transonic</td>
			<td>ME3PXL-M5</td>
			<td>Perfusion circuit flow sensor</td>
		</tr>
		<tr>
			<td>Transonic tubing flow module</td>
			<td>Transonic</td>
			<td>TS410</td>
			<td>flow acquiring system</td>
		</tr>
		<tr>
			<td>Watson - Marlow pumps</td>
			<td>Harvard apparatus</td>
			<td>010.6131.DAO</td>
			<td>Peristaltic pump used for recirculate perfusate</td>
		</tr>
		<tr>
			<td>WBC-1510A</td>
			<td>JEIO TECH</td>
			<td>E03056D</td>
			<td>Heating bath</td>
		</tr>
		<tr>
			<td>Sprague-Dawley rats</td>
			<td>Samtako Bio Korea Co., Ltd., Osan City Korea</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Medications</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>BioHAnce Gel Eye Drops</td>
			<td>SENTRIX Animal care</td>
			<td></td>
			<td>wet ointments for eye</td>
		</tr>
		<tr>
			<td>Cefazolin</td>
			<td>JW pharmaceutical</td>
			<td></td>
			<td>For prophilaxis</td>
		</tr>
		<tr>
			<td>Custodiol</td>
			<td>DR, FRANZ KOHLER CHEMIE GMBH</td>
			<td></td>
			<td>For heart harvesting</td>
		</tr>
		<tr>
			<td>Diclofenac</td>
			<td>Myungmoon Pharm. Co. Ltd</td>
			<td></td>
			<td>For pain control</td>
		</tr>
		<tr>
			<td>Heparin</td>
			<td>JW pharmaceutical</td>
			<td></td>
			<td>Anticoagulant</td>
		</tr>
		<tr>
			<td>Insulin</td>
			<td>JW pharmaceutical</td>
			<td></td>
			<td>hormon therapy</td>
		</tr>
		<tr>
			<td>Saline</td>
			<td>JW pharmaceutical</td>
			<td></td>
			<td>For hydration therapy</td>
		</tr>
	</tbody>
</table>

rat model of normothermic ex-situ perfused heterotopic heart transplantation

Heart transplantation is the most effective therapy for end-stage heart failure. Despite the improvements in therapeutic approaches and interventions, the number of heart failure patients waiting for transplantation is still increasing. The normothermic ex situ preservation technique has been established as a comparable method to the conventional static cold storage technique. The main advantage of this technique is that donor hearts can be preserved for up to 12 h in a physiologic condition. Moreover, this technique allows resuscitation of the donor hearts after circulatory death and applies required pharmacologic interventions to improve donor function after implantation. Numerous animal models have been established to improve normothermic ex situ preservation techniques and eliminate preservation-related complications. Although large animal models are easy to handle compared to small animal models, it is costly and challenging. We present a rat model of normothermic ex situ donor heart preservation followed by heterotopic abdominal transplantation. This model is relatively cheap and can be accomplished by a single experimenter.

Figure 1 illustrates the experimental design used in a small animal model. Figure 2 displays the modified Langendorff perfusion apparatus, which includes a small animal oxygenator. The order of anastomosis for heterotopic abdominal implantation is presented in Figure 3.
Figure 4 shows the parameters used to assess the viability of the heart during ex situ perfusion, ...

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Rat Model of Normothermic Ex-Situ Perfused Heterotopic Heart Transplantation

Here, we present an assessment protocol of a heterotopically implanted heart after normothermic ex situ preservation in the rat model.

Heart transplantation is the most effective therapy for end-stage heart failure. Despite the improvements in therapeutic approaches and interventions, the ...

We have developed a model to reduce complications associated with normothermic ex-situ perfusion and increase the safe preservation time for donor hearts. Compared to the alternative animal models, this model is simple and cost-effective, and can be executed by a single experimenter. This model can be useful in testing the long-term effectiveness of pharmacologic and genetic interventions on the donor hearts after transplantations.The surgical procedure requires microsurgical skill. The key factor in achieving success in this model is to practice and focus on the critical steps outlined in the manuscript. To begin, assemble the Langendorff apparatus, including the oxygenator, pump, and perfusion lines.Fill the perfusion circuit with 20 milliliters of saline solution, and circulate it until it is primed with autologous blood. On the anesthetized donor rat, make a 7-centimeter mid-line abdominal incision, and then bilateral incisions measuring 3 centimeters from the xiphoid process to the mid-clavicle. Remove the pelt from the thoracic region.Inject 1, 000 international unit heparin dissolved in 0.3 milliliters of isotonic saline through the inferior vena cava using a 1-milliliter syringe Stop any bleeding from the needle hole by gently compressing it with a cotton swab. Insert a 5-French femoral catheter into the abdominal aorta. Ensure that the catheter tip reaches the aortic arch, and confirm the catheter location by assessing the approximate length of the inserted part of the catheter.Collect around 10 milliliters of blood via the catheter inserted in the abdominal aorta. Connect the cardioplegic solution perfusion line to the abdominal catheter, and start the cardioplegic solution administration with the syringe pump at a rate of 800 milliliters per hour. Open the thoracic cavity from the diaphragm, and cut the inferior vena cava close to the diaphragm to prevent ventricular distension.Cut the ribs bilaterally along the thoracic spine up to the thoracic inlet. Reflect the mobilized ventral chest wall superiorly with mosquito forceps. After administering all the cardioplegic solution, isolate the aortic arch from the surrounding tissues, and carefully dissect it just below the left subclavian artery.Transect the brachiocephalic and left common carotid arteries at a distant position, leaving the longer stumps of the aortic arch for easy handling during aorta cannulation. Then transect the main pulmonary artery as close as possible to the bifurcation. Carefully ligate the superior vena cava and inferior vena cava with 5-0 silk sutures, preventing the obstruction of the right atrium and coronary sinus.Cover the left margins of the thorax with wet gauze, place the heart onto it, and gently retract the superior vena cava and inferior vena cava ligatures to expose the hilum. Ligate the pulmonary and azygos veins together with a 5-0 silk suture. Sever the tissue dorsal to the ligature and extract the heart.Weigh the heart after examining it for any injury. Replace the saline-primed circuit with blood priming, and start the perfusion at a flow rate of two to three milliliters per minute, allowing the perfusate to leak from the cannulation site to remove any air bubbles. After placing the permanent ligature, ensure the heart begins to contract within a few seconds, and reaches a normal rhythm in 60 seconds.A mean perfusion pressure of 55 to 65 millimeters of mercury with a coronary flow rate of three to four milliliters at 37 degrees Celsius indicates adequate perfusion. Collect 0.15 milliliters of blood from the reservoir, and check the blood gas analysis at the beginning of perfusion and every 20 minutes thereafter. After 120 minutes of perfusion, administer three milliliters of Custodiol through the syringe pump at a rate of 250 milliliters per hour to arrest the heart.Perform the mid-line laparotomy and insert a retractor to widen the abdominal cavity. Mobilize the abdominal organs to the left side of the recipient using cotton swabs to make space for the procedure. Utilizing a surgical microscope with a 10x magnification, mobilize the duodenum and proximal jejunum by blunt dissection with cotton swabs.to expose the abdominal aorta and inferior vena cava. Place 5-0 silk ligatures on the mesenteric branches of both the cranial and caudal sides of the major vessels. Elevate the abdominal vessels and coagulate or ligate the lumbar branches with 5-0 silk sutures.Remember to spare the testicular arteries and veins, and do not clamp them. Use ligatures to lift the vessels and position the micro-clamps to the mesenteric branches, caudal, and cranial sides of the major vessels to stop the blood flow at the anastomosis site. Puncture the aorta using a 27-gauge needle, and elongate the incision with micro scissors to a length equal to or slightly larger than the opening of the donor ascending aorta.Make a longitudinal incision of the inferior vena cava in the same way as the aortotomy, but make it three millimeters closer to the caudal side compared to the aorta incision. Starting the anastomoses, place the donor heart on the right side of the recipient's abdomen, and attach the donor ascending aorta to the recipient's abdominal aorta with one simple interrupted stitch at the cranial corner of the longitudinal incision. Move the heart to the left side of the recipient's abdomen, and perform anastomosis of the donor's ascending aorta with the recipient's abdominal aorta, using a running 9-0 polypropylene suture.Fixate the donor pulmonary artery to the inferior vena cava with two interrupted sutures at the caudal and cranial corners of the longitudinal incision. After completion of the anastomosis, remove the caudal clamp and the cranial clamp. Insuring adequate hemostasis, replace the abdominal organs in a meander-like manner, and close the layers of the abdominal incision using continuous 5-0 polypropylene sutures.The parameters used to assess the viability of the heart during ex-situ perfusion, such as lactate, potassium, and mean aortic pressure are shown in this figure. Here, the use of normothermic ex-situ preservation decreased the total ischemic time of six successful cases to 46.2 plus-minus 4.7 minutes, while the total out-of-body time was 166.2 plus-minus 4.7 minutes. The extraction of the heart from the donor and preparation for ex-situ perfusion and heterotopic transplantation required was 5.8 plus-minus 1.3 minutes.The overall success rate of the surgery was 70%and the mean anastomosis time of the six successful cases was 38.4 plus-minus 3.4 minutes. The electrophysiologic performance of the donor heart before procurement and after implantation is presented in this figure. In all the experiments, the heart rate significantly decreased immediately after implantation, but it eventually recovered over time.The macroscopic and microscopic appearance of the donor heart before normothermic ex-situ preservation, after normothermic ex-situ preservation, and after two hours of heterotopic implantation are shown here. When doing this procedure, it's important to take enough blood for perfusion, carefully cut the aorta without damaging the ascending part, and closely watch the physiological parameters during preservation. Following this procedure, we can test the effectiveness of novel preservation solutions and the recipient's immune response to newly-introduced preservation methods.With the combination of ex-situ perfusion and heterotopic transplantation, we are able to investigate novel techniques through elongate preservation time, and observe the long-term impact on the recipient immune response.

rat-model-normothermic-ex-situ-perfused-heterotopic-heart

Research

JoVE Journal

Medicine

885 Aufrufe.  Chonnam National University Graduate School. Wir haben ein Modell entwickelt, um Komplikationen im Zusammenhang mit der normothermen Ex-situ-Perfusion zu reduzieren und die sichere Konservierungszeit für Spenderherzen zu erhöhen. Im Vergleich zu den alternativen Tiermodellen ist dieses Modell einfach und kostengünstig und kann von einem einzigen Versuchsleiter durchgeführt werden. Dieses Modell kann nützlich sein, um die langfristige Wirksamkeit pharmakologischer und genetischer Interventionen an den Spenderherzen nach Transplantat...