Name: isolated lung perfusion system in the rabbit model
Uploaded: 2021-07-15T14:30:00
Description: The isolated lung perfusion system has been widely used in pulmonary research, contributing to elucidate the lungs&#39; inner workings, both micro and ...

The authors would like to thank Ph.D. Bettina Sommer Cervantes for her support in the writing of this manuscript, and Kitzia Elena Lara Safont for her support with the illustrations.

The isolated perfusion system in the rabbit model has been widely used in the Bronchial Hyperresponsiveness Laboratory at the Instituto Nacional de Enfermedades Respiratorias. The protocol includes New Zealand rabbits with an approximate weight of 2.5-3 kg. All animals were kept in standard vivarium conditions and ad libitum feeding in compliance with the official Mexican guidelines for laboratory animals (NOM 062-ZOO-1999) and under the Guide for the Care and Use of Laboratory Animals (8th edition, 2...

<ol>
	<li>Dixon, W. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Contributions+to+the+physiology+of+the+lungs:+Part+I.+The+bronchial+muscles,+their+innervation,+and+the+action+of+drugs+upon+them.">Contributions to the physiology of the lungs: Part I. The bronchial muscles, their innervation, and the action of drugs upon them.</a> The Journal of Physiology. 29 (2), 97-173 (1903).</li><li>Nelson, K., 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=Animal+models+of+ex+vivo+lung+perfusion+as+a+platform+for+transplantation+research.">Animal models of ex vivo lung perfusion as a platform for transplantation research.</a> World Journal of Experimental Medicine. 4 (2), 7-15 (2014).</li><li>Roman, M. A., Nair, S., Tsui, S., Dunning, J., Parmar, J. S. <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+lung+perfusion:+a+comprehensive+review+of+the+development+and+exploration+of+future+trends.">Ex vivo lung perfusion: a comprehensive review of the development and exploration of future trends.</a> Transplantation. 96 (6), 509-518 (2013).</li><li>Delaunois, A., Gustin, P., Ansay, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multiple+muscarinic+receptor+subtypes+mediating+pulmonary+oedema+in+the+rabbit.">Multiple muscarinic receptor subtypes mediating pulmonary oedema in the rabbit.</a> Pulmonary Pharmacology. 7 (3), 185-193 (1994).</li><li>Delaunois, A., Gustin, P., Vargas, M., Ansay, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Protective+effect+of+various+antagonists+of+inflammatory+mediators+against+paraoxon-induced+pulmonary+edema+in+the+rabbit.">Protective effect of various antagonists of inflammatory mediators against paraoxon-induced pulmonary edema in the rabbit.</a> Toxicology and Applied Pharmacology. 132 (2), 343-345 (1995).</li><li>Barr, H. A., Nicholas, T. E., Power, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Control+of+alveolar+surfactant+in+rats+at+rest+and+during+prolonged+hyperpnoea:+pharmacological+evidence+for+two+tissue+pools+of+surfactant.">Control of alveolar surfactant in rats at rest and during prolonged hyperpnoea: pharmacological evidence for two tissue pools of surfactant.</a> British Journal of Pharmacology. 93 (3), 473-482 (1988).</li><li>Machuca, T. N., Cypel, M. <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+lung+perfusion.">Ex vivo lung perfusion.</a> Journal of Thoracic Disease. 6 (8), 1054-1062 (2014).</li><li>Steen, 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=First+human+transplantation+of+a+nonacceptable+donor+lung+after+reconditioning+ex+vivo.">First human transplantation of a nonacceptable donor lung after reconditioning ex vivo.</a> The Annals of Thoracic Surgery. 83 (6), 2191-2194 (2007).</li><li>Cypel, 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=Technique+for+prolonged+normothermic+ex+vivo+lung+perfusion.">Technique for prolonged normothermic ex vivo lung perfusion.</a> The Journal of Heart and Lung Transplantation: The Official Publication of the International Society for Heart and Lung Transplantation. 27 (12), 1319-1325 (2008).</li><li>Cypel, 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=Normothermic+ex+vivo+lung+perfusion+in+clinical+lung+transplantation.">Normothermic ex vivo lung perfusion in clinical lung transplantation.</a> New England Journal of Medicine. 364 (15), 1431-1440 (2011).</li><li>Kao, C. C., Parulekar, A. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Is+perfusate+exchange+during.">Is perfusate exchange during.</a> Annals of Translational Medicine. 8 (3), 43 (2020).</li><li>Alquicira-Mireles, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Participaci&#243;n de la serotonina en los cambios de permeabilidad vascular en la preservaci&#243;n pulmonar en conejo. , (2013).</li><li>Arreola-Ram&#237;rez, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Papel de la liberaci&#243;n de acetilcolina y sustancia P en el deterioro de la funci&#243;n pulmonar en un modelo experimental de preservaci&#243;n pulmonar en conejo. , (2009).</li><li>Isolated lung perfusion systems for small to large animal models. Harvard Apparatus. Hugo Sachs Elektronik (HSE) Available from: <a target="_blank" href="https://www.harvardapparatus.com/media/harvard/pdf/Isolated%20Lung%20Perfusion%20Systems%20Brochure.pdf">https://www.harvardapparatus.com/media/harvard/pdf/Isolated%20Lung%20Perfusion%20Systems%20Brochure.pdf</a> (2021)</li><li>Jiao, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evolving+trend+of+EVLP:+Advancements+and+emerging+pathways.">Evolving trend of EVLP: Advancements and emerging pathways.</a> SN Comprehensive Clinical Medicine. 1 (4), 287-303 (2019).</li><li>Mordant, 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=Mesenchymal+stem+cell+treatment+is+associated+with+decreased+perfusate+concentration+of+interleukin-8+during+ex+vivo+perfusion+of+donor+lungs+after+18-hour+preservation.">Mesenchymal stem cell treatment is associated with decreased perfusate concentration of interleukin-8 during ex vivo perfusion of donor lungs after 18-hour preservation.</a> The Journal of Heart and Lung Transplantation: The Official Publication of the International Society for Heart and Lung Transplantation. 35 (10), 1245-1254 (2016).</li><li>Cowan, P. J., Hawthorne, W. J., Nottle, M. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Xenogeneic+transplantation+and+tolerance+in+the+era+of+CRISPR-Cas9.">Xenogeneic transplantation and tolerance in the era of CRISPR-Cas9.</a> Current Opinion in Organ Transplantation. 24 (1), 5-11 (2019).</li><li>Collaborators, G. C. R. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prevalence+and+attributable+health+burden+of+chronic+respiratory+diseases,+1990-2017:+a+systematic+analysis+for+the+Global+Burden+of+Disease+Study+2017.">Prevalence and attributable health burden of chronic respiratory diseases, 1990-2017: a systematic analysis for the Global Burden of Disease Study 2017.</a> The Lancet Respiratory Medicine. 8 (6), 585-596 (2020).</li><li>Bravo-Reyna, C. C., Torres-Villalobos, G., Aguilar-Blas, N., Fr&#237;as-Guill&#233;n, J., Guerra-Mora, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparative+study+of+capillary+filtration+coefficient+(Kfc)+determination+by+a+manual+and+automatic+perfusion+system.+Step+by+step+technique+review.">Comparative study of capillary filtration coefficient (Kfc) determination by a manual and automatic perfusion system. Step by step technique review.</a> Physiological Research. 68 (6), 901-908 (2019).</li><li>Pereira, M. R., 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=COVID-19+in+solid+organ+transplant+recipients:+Initial+report+from+the+US+epicenter.">COVID-19 in solid organ transplant recipients: Initial report from the US epicenter.</a> American Journal of Transplantation. 20 (7), 1800-1808 (2020).</li></ol>

This work displays a general view of the isolated lung perfusion system, an essential technique in pulmonary physiology research. The isolated lung perfusion system offers a great degree of versatility in its uses and allows the evaluation of several parameters relevant in the testing of a wide range of hypotheses15. An isolated lung system is a tool with worldwide presence that, in the last decade, has further established its relevance for organ-specific evaluations and also expanded its usefulne...

Brodie and Dixon first described the ex-vivo lung perfusion system in 1903 1. Since then, it has become a gold standard tool for studying the physiology, pharmacology, toxicology, and biochemistry of the lungs2,3. The technique offers a consistent and reproducible way to evaluate the viability of lung transplants, and to determine the effect of inflammatory mediators such as histamine, arachidonic acid metabolites, and substance P, among others, as well as their interactions during pulmonary phenomena such as bronchoconstriction, atelectasis, and pulmonary edema. The isolated lung system has been a key technique in unveiling the important role of the lungs in the elimination of biogenic amines from general circulation4,5. Additionally, the system has been used to evaluate the biochemistry of pulmonary surfactant6. Over the last few decades, the ex-vivo lung perfusion system has become an ideal platform for lung transplantation research7. In 2001 a team lead by Stig Steen described the first clinical application of the ex-vivo lung perfusion system by using it to recondition the lungs of a 19-year-old donor, who was initially rejected by transplantation centers due to its injuries. The left lung was harvested and perfused for 65 min; afterward, it was successfully transplanted into a 70-year-old man with COPD8. Further research into lung reconditioning using the ex-vivo perfusion led to developing the Toronto technique for extended lung perfusion to assess and treat injured donor lungs9,10. Clinically, the ex-vivo lung perfusion system has shown to be a safe strategy to increase donor pools by treating and reconditioning sub-standard donor lungs, presenting no significant difference in risks or outcomes against standard criteria donors10. 
The main advantage of the isolated lung perfusion system is that the experimental parameters can be evaluated in a complete functional organ that preserves its physiological function under an artificial laboratory setup. Furthermore, it allows the measurement and manipulation of pulmonary mechanical ventilation to analyze the components of pulmonary physiology such as airway resistance, total vascular resistance, gas exchange, and edema formation, which to date cannot be measured precisely in vivo on lab animals2. Notably, the composition of the solution with which the lung is perfused can be fully controlled, enabling the addition of substances to evaluate their effects in real-time and sample collection from perfusion for further study11. Researchers working with the isolated lung system should bear in mind that mechanical ventilation causes decay of the pulmonary tissue shortening its useful time. This progressive fall in mechanical parameters can be significantly delayed by hyperinflating the lungs occasionally during the time of the experiment4. Still, the preparation cannot usually last more than eight hours. Another consideration for the ex-vivo lung perfusion system is the absence of central nervous regulation and lymphatic drainage. The effects of their absence are not yet fully understood and could potentially be a source of bias in certain experiments. 
The isolated lung perfusion system technique can be performed in the rabbit model with a high degree of consistency and reproducibility. This work describes the technical and surgical procedures for the implementation of the ex-vivo isolated lung perfusion technique as developed for the rabbit model at Instituto Nacional de Enfermedades Respiratorias in Mexico City, intending to share the insights and provide a clear guide on key steps in the application of this experimental model.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>2-Stop Tygon E-Lab Tubing, 3.17 mm ID, 12/pack, Black/White</td>
			<td>Hugo Sachs Elektronik (HSE)</td>
			<td>73-1864</td>
			<td></td>
		</tr>
		<tr>
			<td>Adapter for Positive Pressure Ventilation on IPL-4</td>
			<td>Hugo Sachs Elektronik (HSE)</td>
			<td>73-4312</td>
			<td></td>
		</tr>
		<tr>
			<td>Adapter for Positive Pressure Ventilation on IPL-4</td>
			<td>Hugo Sachs Elektronik (HSE)</td>
			<td>73-4312</td>
			<td></td>
		</tr>
		<tr>
			<td>Alternative Pressure-Free Gas Supply for IPL-4: To supply the trachea with gas mixture different from room air during negative ventilation</td>
			<td>Hugo Sachs Elektronik (HSE)</td>
			<td>73-4309</td>
			<td></td>
		</tr>
		<tr>
			<td>Base Unit for the Rabbit to Fetal Pig Isolated Perfused Lung</td>
			<td>Hugo Sachs Elektronik (HSE)</td>
			<td>73-4138</td>
			<td></td>
		</tr>
		<tr>
			<td>Bovine serum A2:D41albumin lyophilized powder</td>
			<td>sigma</td>
			<td>3912</td>
			<td>500 g</td>
		</tr>
		<tr>
			<td>Calcium chloride, CaCl2&#183;2H2O.</td>
			<td>JT Baker</td>
			<td>10035-04-8</td>
			<td></td>
		</tr>
		<tr>
			<td>Cryogenic vials</td>
			<td>Corning</td>
			<td>430659</td>
			<td>2 mL</td>
		</tr>
		<tr>
			<td>D-glucosa, C6H12O6.</td>
			<td>sigma</td>
			<td>G5767</td>
			<td></td>
		</tr>
		<tr>
			<td>Differential Low Pressure Transducer DLP2.5, Range +- 2.5 cmH2O, HSE Connector</td>
			<td>Hugo Sachs Elektronik (HSE)</td>
			<td>73-3882</td>
			<td></td>
		</tr>
		<tr>
			<td>Differential Pressure Transducer MPX, Range +- 100 cmH2O, HSE Connector</td>
			<td>Hugo Sachs Elektronik (HSE)</td>
			<td>73-0064</td>
			<td></td>
		</tr>
		<tr>
			<td>Eppendorf tubes</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol absolute HPLC grade</td>
			<td>Caledon</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Falcon tubes</td>
			<td></td>
			<td></td>
			<td>14 mL</td>
		</tr>
		<tr>
			<td>Harvard Peristaltic Pump P-230 (Complete with Control Box and P-230 Motor Drive)</td>
			<td>Hugo Sachs Elektronik (HSE)</td>
			<td>70-7001</td>
			<td></td>
		</tr>
		<tr>
			<td>Heated Linear Pneumotachometer 0 to 10 L/min flow range</td>
			<td>Hugo Sachs Elektronik (HSE)</td>
			<td>59-9349</td>
			<td></td>
		</tr>
		<tr>
			<td>Heater Controller for Single Pneumotachometer 230 VAC, 50 Hz</td>
			<td>Hugo Sachs Elektronik (HSE)</td>
			<td>59-9703</td>
			<td></td>
		</tr>
		<tr>
			<td>Heparin</td>
			<td>PISA</td>
			<td></td>
			<td>5000 UI</td>
		</tr>
		<tr>
			<td>HPLC Column (C18 100A 5U)</td>
			<td>Alltech</td>
			<td>98121213</td>
			<td>150 mm x 4.6 mm</td>
		</tr>
		<tr>
			<td>Hydrophilic Syringe Filter</td>
			<td>Millex</td>
			<td>SLLGR04NL</td>
			<td>4 mm</td>
		</tr>
		<tr>
			<td>IPL-4 Core System for Isolated Rabbit to Fetal Pig Lung, 230</td>
			<td>Hugo Sachs Elektronik (HSE)</td>
			<td>73-4296</td>
			<td></td>
		</tr>
		<tr>
			<td>IPL-4 Core System for Isolated Rabbit to Fetal Pig Lung, 230 V</td>
			<td>Hugo Sachs Elektronik (HSE)</td>
			<td>73-4296</td>
			<td></td>
		</tr>
		<tr>
			<td>Jacketed Glass Reservoir for Buffer Solution, with Frit and Tubing, 6.0 L</td>
			<td>Hugo Sachs Elektronik (HSE)</td>
			<td>73-0322</td>
			<td></td>
		</tr>
		<tr>
			<td>Lauda Thermostatic Circulator, Type E-103, 230 V/50 Hz, 3 L Bath Volume, Temperature Range 20 to 150&#176;C</td>
			<td>Hugo Sachs Elektronik (HSE)</td>
			<td>73-0125</td>
			<td></td>
		</tr>
		<tr>
			<td>Left Atrium Cannula for Rabbit with Basket, OD 5.9 mm</td>
			<td>Hugo Sachs Elektronik (HSE)</td>
			<td>73-4162</td>
			<td></td>
		</tr>
		<tr>
			<td>Low Range Blood Pressure Transducer P75 for PLUGSYS Module</td>
			<td>Hugo Sachs Elektronik (HSE)</td>
			<td>73-0020</td>
			<td></td>
		</tr>
		<tr>
			<td>Magnesium sulfate heptahydrate, MgSO4&#183;7H2O</td>
			<td>JT Baker</td>
			<td>10034-99-8</td>
			<td></td>
		</tr>
		<tr>
			<td>Microcentrifuge Tube</td>
			<td>Corning</td>
			<td>430909</td>
			<td></td>
		</tr>
		<tr>
			<td>Negative Pressure Ventilation Control Option with Pressure Regulator for IPL-4</td>
			<td>Hugo Sachs Elektronik (HSE)</td>
			<td>73-4298</td>
			<td></td>
		</tr>
		<tr>
			<td>New Zeland rabbits</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>PISABENTAL (Pentobarbital sodium)</td>
			<td>PISA</td>
			<td>Q-7833-215</td>
			<td></td>
		</tr>
		<tr>
			<td>PLUGSYS Case, Type 603* 7</td>
			<td>Hugo Sachs Elektronik (HSE)</td>
			<td>73-0045</td>
			<td></td>
		</tr>
		<tr>
			<td>PLUGSYS TCM Time Counter Module</td>
			<td>Hugo Sachs Elektronik (HSE)</td>
			<td>73-1750</td>
			<td></td>
		</tr>
		<tr>
			<td>PLUGSYS Transducer Amplifier Module (TAM-A)</td>
			<td>Hugo Sachs Elektronik (HSE)</td>
			<td>73-0065</td>
			<td></td>
		</tr>
		<tr>
			<td>PLUGSYS Transducer Amplifier Module (TAM-D)</td>
			<td>Hugo Sachs Elektronik (HSE)</td>
			<td>73-1793</td>
			<td></td>
		</tr>
		<tr>
			<td>PLUGSYS VCM-4R Ventilation Control Module with Pressure Regulator</td>
			<td>Hugo Sachs Elektronik (HSE)</td>
			<td>73-1755</td>
			<td></td>
		</tr>
		<tr>
			<td>Potassium chloride, KCl.</td>
			<td>JT Baker</td>
			<td>3040-01</td>
			<td></td>
		</tr>
		<tr>
			<td>Potassium dihydrogen phosphate, KH2PO4</td>
			<td>JT Baker</td>
			<td>7778-77-0</td>
			<td></td>
		</tr>
		<tr>
			<td>PROCIN (Xylacine clorhydrate)</td>
			<td>PISA</td>
			<td>Q-7833-099</td>
			<td></td>
		</tr>
		<tr>
			<td>Pulmonary Artery Cannula for Rabbit with Basket, OD 4.6 mm</td>
			<td>Hugo Sachs Elektronik (HSE)</td>
			<td>73-4161</td>
			<td></td>
		</tr>
		<tr>
			<td>Scalpel knife</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Serotonin 5-HT</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Servo Controller for Perfusion (SCP</td>
			<td>Hugo Sachs Elektronik (HSE)</td>
			<td>73-2806</td>
			<td></td>
		</tr>
		<tr>
			<td>Snap Cap Microcentrifuge Tube</td>
			<td>Costar</td>
			<td>3620</td>
			<td>1.7 mL</td>
		</tr>
		<tr>
			<td>Sodium bicarbonate, NaHCO3</td>
			<td>sigma</td>
			<td>S6014</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium chloride, NaCl.</td>
			<td>sigma</td>
			<td>S9888</td>
			<td></td>
		</tr>
		<tr>
			<td>Surgical gloves No. 7 1/2</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Surgical gloves No. 8</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Taygon tubes</td>
			<td>Masterflex</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Tracheal Cannula for Rabbit, OD 5.0 mm</td>
			<td>Hugo Sachs Elektronik (HSE)</td>
			<td>73-4163</td>
			<td></td>
		</tr>
	</tbody>
</table>

isolated lung perfusion system in the rabbit model

The isolated lung perfusion system has been widely used in pulmonary research, contributing to elucidate the lungs&#39; inner workings, both micro and macroscopically. This technique is useful in the characterization of pulmonary physiology and pathology by measuring metabolic activities and respiratory functions, including interactions between circulatory substances and the effects of inhaled or perfused substances, as in drug testing. While in vitro methods involve the slicing and culturing of tissues, the isolated ex vivo lung perfusion system allows to work with a complete functional organ making possible the study of a continuous physiological function while recreating ventilation and perfusion. However, it should be noted that the effects of the absence of central innervation and lymphatic drainage still have to be fully assessed. This protocol aims to describe the assembly of the isolated lung apparatus, followed by the surgical extraction and cannulation of lungs and heart from experimental lab animals, as well as to display the perfusion technique and signal processing of data. The average viability of the isolated lung ranges between 5-8 h; during this period, the pulmonary capillary permeability increases, causing edema and lung injury. The functionality of preserved pulmonary tissue is measured by the capillary filtration coefficient (Kfc), used to determine the extent of pulmonary edema through time.

The isolated lung perfusion system allows organ manipulation for biopsy, sample collection from perfusion, and real-time data collection of physiological parameters. The isolated system can be used to test many hypotheses involving different functions and lung phenomena, from metabolic and enzymatic activity to edema formation and preservation periods for lung transplants.
Figure 1&#160;displays a diagram of the fully assembled isolated lung perfusion system along...

The isolated rabbit lung preparation is a gold standard tool in pulmonary research. This publication aims to describe the technique as developed for the study of physiological and pathological mechanisms involved in airway reactivity, lung preservation, and preclinical research in lung transplantation and pulmonary edema.

Isolated Lung Perfusion System in the Rabbit Model

The isolated lung perfusion system has been widely used in pulmonary research, contributing to elucidate the lungs&#39; inner workings, both micro and ...

This technique is useful in the characterization of pulmonary physiology and pathology by measuring metabolic activities and respiratory function. Isolated lung perfusion system allows to work with a complete functional organ making possible the study of a continuous physiological function while recreating ventilation and perfusion. This method could provide insight into the characterization of the non-respiratory capabilities of the pulmonary tissues, such as metabolic activity and the activities of various components like alveolar macrophage and endothelial tissue.To begin with, assemble the working apparatus, ensuring that it contains the main steel column mounted on a base plate holding the artificial thorax with the pneumotachometer and weight transducer located above the column and behind the preheating coil with a bubble trap. Connect all the transducers to the central electronics unit and prepare the ventilation system besides the apparatus. After shaving the surgical site of the anesthetized rabbit, make a ventral median line incision of three to five centimeters from the sternum manubrium up to the neck.Use the operating scissors to cut the anterior 2/3 of the trachea between the cartilage rings. Insert a five millimeter tracheal cannula through the tracheal fibrous membrane and fix the cannula carefully with a 4-0 silk suture. Place the forceps or tweezers underneath the trachea to ensure the cannula does not bend against the trachea.Connect the respiration pump to the tracheal cannula, set the tidal volume at 10 milliliters per kilogram and initiate the ventilation quickly after the tracheotomy and before the thorax is opened to maintain positive pressure in the lungs for preventing lung collapse during the surgery. To access the thoracic cavity, use a scalpel or scissors to open the thorax wall and perform a medial sternotomy up to the upper third of the thorax. Hold the thorax halves open with two retractors.Localize the superior and inferior vena cava and tag them with threads. Before the exsanguination of the animal, identify the right ventricle and inject 1, 000 international units per kilogram of heparin. Immediately after the injection, ligate the superior and inferior vena cava with the pre-looped thread.Cut through the manubrium sterni to extend the medial sternotomy towards the tracheal cannula, releasing the trachea on both sides from connecting tissue. Now resect the trachea above the tracheal cannula and gently pull up the cannula in a cranial/caudal axis. After exsanguination for harvesting the cardiopulmonary block, use direct digital dissection or spring scissors to separate the connective tissue and remove the lungs from the thorax.Next, dissect the vasculature and esophagus. Lift the isolated lungs out of the thorax and carefully place the lungs over a sterile gauze on a Petri dish. To prevent atelectasis, ventilate the lungs using positive pressure ventilation with positive end expiratory pressure set at two centimeters of water column.Cut the ventricles off the heart at the level of the atrioventricular groove. After opening the two ventricles, introduce the pulmonary artery cannula through the right pulmonary artery and the left atrium cannula through the mitral valve into the left atrium. Fix the cannulae with a 4-0 silk suture including the surrounding tissues in the ligatures of the pulmonary artery and left atrium to avoid structural distension.Inject 250 milliliters of saline isotonic solution through the arterial cannula to flush the remaining blood from the vascular bed. For the perfusion setup, place the isolated lungs carefully into the lung chamber. Attach the trachea to the transductor on the chamber cover and connect the cannulated vessels to the perfusion system, then close and secure the chamber with the rotary lock.Next, attach the chamber lid and switch over the stopcock to shift from positive to negative pressure ventilation. Perfuse the lungs with 200 milliliters of artificial blood-free perfusate starting with the flow at three milliliters per minute per kilogram, then slowly step up the flow over five minutes to five milliliters per minute per kilogram. And for the next five minutes, allow the flow to reach eight milliliters per minute per kilogram, followed by a maximum flux of 10 milliliters per minute per kilogram for five minutes.Ventilate the lungs with humidified air at a frequency of 30 beats per minute, a tidal volume of 10 milliliters per kilogram and an end expiratory pressure of two centimeters of water column. To achieve zone three conditions, wait for 10 to 15 minutes to obtain an equilibrium characterized by an ISO gravimetric state, ensuring that the venous pressure is stable throughout the registry. Ensure that the weight of the lung remains constant and the arterial and left atrial pressures are stable to achieve zone three conditions to open up a maximum number of pulmonary vessels and maintain the microvascular bed content during the experiment.For the electronic control and signal processing, ensure that the respiratory flow, weight changes, microvascular pressure, tidal volume, vascular resistance, among others, are registered on a multiple central electronics unit that integrates signals coming from the transducers and displays them on the evaluation system. The concentration of 5-HT and monoamine oxidase involved in the lung metabolism and vascular permeability were assessed. The concentration of 5-HT and monoamine oxidase peaked after 15 minutes of preservation and then decreased during the next six hours.Afterward, perfusion levels showed a non-statistically significant increase up to 24 hours. The release rates of 5-HT and monoamine oxidase indicated that during the first hour of the preservation, 5-HT levels rose higher than monoamine oxidase and decreased within six hours after being recaptured by endothelial cells and platelets, as well as monoamine oxidase-mediated catabolism. Neutral endopeptidase activity increased at nine hours and then decreased and remained stable during 12 to 24 hours.Angiotensin-converting enzyme activity decreased after four hours, then increased and remained stable through time til 24 hours. The effect of pulmonary preservation in capillary permeability was assessed for 24 hours, indicating that the perfused lung suffered a progressive increase in capillary filtration coefficient. The effect of different additives in the capillary permeability of the isolated lung perfusion system under diverse conditions was checked and a maximum increase in the permeability was observed with atropin.The most important maneuver is to correctly place the lungs into a lung chamber and connect the cannulated vessels to the perfusion system. The implications of this technique extend toward interactions between circulatory substances and the effects of inhaled or perfused substances as in drug testing and various lung pathologies.

Research

JoVE Journal

Medicine

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