Name: a rat lung transplantation model of warm ischemia/reperfusion injury: optimizations to improve outcomes
Uploaded: 2021-10-28T14:00:00
Description: Watch this Scientific Journal Video about A Rat Lung Transplantation Model of Warm Ischemia/Reperfusion Injury: Optimizations to Improve Outcomes at JoVE.com

Male Sprague-Dawley rats (180-270 g body weight) were purchased commercially (e.g., Envigo) and were housed under pathogen-free conditions at The Ohio State University Animal Facility. All procedures were humanely performed according to the NIH and the National Research Council&#39;s Guide for the Humane Care and Use of Laboratory Animals and with the approval of The Ohio State University Institutional Animal Care and Use Committee (IACUC Protocol # 2012A00000135-R2).
1. Initial setup
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<ol>
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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=Standardization+of+bronchoalveolar+lavage+method+based+on+suction+frequency+number+and+lavage+fraction+number+using+rats.">Standardization of bronchoalveolar lavage method based on suction frequency number and lavage fraction number using rats.</a> Toxicological Research. 26 (3), 203-208 (2010).</li><li>Chang, J. E., Kim, H. J., Yi, E., Jheon, S., Kim, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reduction+of+ischemia-reperfusion+injury+in+a+rat+lung+transplantation+model+by+low-concentration+GV1001.">Reduction of ischemia-reperfusion injury in a rat lung transplantation model by low-concentration GV1001.</a> European Journal of Cardio-Thoracic Surgery. 50 (5), 972-979 (2016).</li><li>De Backer, J. 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S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+obliterative+bronchiolitis+in+a+murine+model+of+orthotopic+lung+transplantation.">Development of obliterative bronchiolitis in a murine model of orthotopic lung transplantation.</a> Journal of Visualized Experiments. (65), e3947 (2012).</li><li>Jia, 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=Treatment+of+acute+lung+injury+by+targeting+MG53-mediated+cell+membrane+repair.">Treatment of acute lung injury by targeting MG53-mediated cell membrane repair.</a> Nature Communications. 5, 4387 (2014).</li><li>Kim, J. L., 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=Pegylated-Catalase+Is+Protective+in+Lung+Ischemic+Injury+and+Oxidative+Stress.">Pegylated-Catalase Is Protective in Lung Ischemic Injury and Oxidative Stress.</a> Annals of Thoracic Surgery. , (2020).</li><li>Beal, E. W., 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=D-Ala(2),+D-Leu(5)]+Enkephalin+Improves+Liver+Preservation+During+Normothermic+Ex+Vivo+Perfusion.">D-Ala(2), D-Leu(5)] Enkephalin Improves Liver Preservation During Normothermic Ex Vivo Perfusion.</a> Journal of Surgical Research. 241 (2), 323-335 (2019).</li><li>Akateh, C., 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=Intrahepatic+Delivery+of+Pegylated+Catalase+Is+Protective+in+a+Rat+Ischemia/Reperfusion+Injury+Model.">Intrahepatic Delivery of Pegylated Catalase Is Protective in a Rat Ischemia/Reperfusion Injury Model.</a> Journal of Surgical Research. 238, 152-163 (2019).</li></ol>

In this report, we have intervened at several critical steps in a rat lung transplantation protocol to optimize the procedure.&#160;While various cuffing techniques for rat lung transplantation has been reported1,2,3,4,5,6,7,8,9...

For over three decades, researchers have been modifying and improving rat lung transplantation models so that the data generated are more consistent and more reflective of the actual clinical condition. In our laboratory&#39;s time performing this model, we have determined four areas of improvement: cuffing techniques for anastomoses, identification of the recipient&#39;s 4th intercostal space, lung inflation and wound closure during the recipient&#39;s procedure, and the harvesting of samples for analysis.
Cuffing technique modifications for anastomoses can improve the entire transplantation procedure by shortening handling time of the donor lung1,2,3,4,5,6 and making the anastomosis procedure faster and technically easier for the microsurgeon. While it is critical to use the proper sized cuffs to supply the necessary blood and airflow to the transplanted lung, there is limited guidance regarding how one should choose the size of cuffs for the pulmonary vein (PV), pulmonary artery (PA), or bronchus (Br)5,7,8,9. Since the diameters of the PV, PA, and Br are related to the body weight of the donor and recipient rats, we propose that the cuff size be based on body weight. This report provides a size guide for cuffs based on a rat&#39;s body weight (180 g to over 270 g) that serves to optimize blood and air supply to the transplanted lung (Table 1).
While a newer microsurgeon can successfully and easily procure a donor lung during the donor procedure, transplanting the lung during the recipient&#39;s procedure is more complicated and is dependent on the microsurgeon&#39;s experience. Attempts to find the 4th intercostal space to access the recipient&#39;s left lung is one of the more difficult steps that holds some subjectivity and can increase the procedure time. Therefore, we introduce a simple and objective method to assist in the identification of the 4th intercostal space location by using chest measurements and the palpitations of the heart to find the correct area chest wall to dissect4,5,6,10,11,12.
We also propose an improvement to donor lung inflation, which is a potential source of injury to the organ. The donor lung is deflated until reperfusion starts. While suturing the 4th intercostal space, the donor lung is commonly inflated by increasing PEEP from 2 cmH2O to 6 cmH2O. In order to minimize lung injury from overinflation, we propose a technique where three 6-0 nylon sutures are placed around the 4th rib inferior to the 5th rib with simple double knots. When it is time for wound closure, the ends of the three sutures are held with hemostats in both hands, the wound is closed all at once by pulling up on each side, and PEEP is immediately reduced to 2 cmH2O. In this way, the lung is allowed to expand for the shortest time possible10.
At the conclusion of an experiment, the researcher often wants to collect many types of samples for many types of analysis from each transplant. For example, snap frozen tissue, formalin fixed tissue, tissue for wet-to-dry weight ratio to determine pulmonary edema, and bronchoalvelolar lavage (BAL) fluid can all be used to assess how well the transplant went. The traditional method of collecting BAL fluid allows for a mixed pooled sample from both the recipient&#39;s native lobes and the donor&#39;s transplanted lobe13,14,15. To overcome this, we present a method of clamping the hilar areas that can yield more precise insight into the transplanted and native lungs&#39; condition. Additionally, the volume of PBS used to collect BAL fluid from each side of the lungs is important to consider because BAL fluid contains numerous soluble factors such as cytokines and chemokines that are measured by concentration. Normalizing the volume of the fluid instilled to the estimated volume of lung capacity can help with comparison. With four lobes on the right side and one lobe on the left side, each of the rat&#39;s five lobes has a different volume and surface area16. According to a previous study on volume measurement of lung lobes by Backer et al., of the total volume of the whole lung the volume of the right lobes is 63% (4400 mm3) and the left lobe is 37% (2500 mm3). Therefore, we recommend that the volume of PBS used to collect BAL fluid should be calculated as twice the tidal volume (7.2 mL/kg) multiplied by 63% for the right lung and 37% for the left lung. By using this approach, one can better control for variables like body weight and timing10,16.
In all, in this report we will demonstrate a few modifications to the standard experimental model of rat lung transplantation that can make the procedure more efficient and increase the capability of generating more accurate and plentiful data from each experiment.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>12 Gauge angio-catheter</td>
			<td>BD</td>
			<td>382277</td>
			<td></td>
		</tr>
		<tr>
			<td>14 Gauge angio-catheter</td>
			<td>B. Braun</td>
			<td>4251717-02</td>
			<td></td>
		</tr>
		<tr>
			<td>16 Gauge angio-catheter</td>
			<td>B. Braun</td>
			<td>4252586-02</td>
			<td></td>
		</tr>
		<tr>
			<td>18 Gauge angio-catheter</td>
			<td>B. Braun</td>
			<td>4251679-02</td>
			<td></td>
		</tr>
		<tr>
			<td>20 Gauge angio-catheter</td>
			<td>B. Braun</td>
			<td>4252527-02</td>
			<td></td>
		</tr>
		<tr>
			<td>4-0 silk suture</td>
			<td>Surgical Specialties Corp.</td>
			<td>SP116</td>
			<td></td>
		</tr>
		<tr>
			<td>6-0 nylon suture</td>
			<td>AD Surgical</td>
			<td>S-N618R13</td>
			<td></td>
		</tr>
		<tr>
			<td>7-0 nylon suture</td>
			<td>AD Surgical</td>
			<td>S-N718SP13</td>
			<td></td>
		</tr>
		<tr>
			<td>8-0 nylon suture</td>
			<td>AD Surgical</td>
			<td>XXS-N807T6</td>
			<td></td>
		</tr>
		<tr>
			<td>Betadine Spray</td>
			<td>Avrio Health L.P</td>
			<td>UPC 367618160039</td>
			<td></td>
		</tr>
		<tr>
			<td>Clippers</td>
			<td>VWR</td>
			<td>MSPP-023326</td>
			<td></td>
		</tr>
		<tr>
			<td>Castroviejo micro dissecting spring scissors</td>
			<td>Roboz Surgical Instrument Co</td>
			<td>RS-5668</td>
			<td></td>
		</tr>
		<tr>
			<td>Dumont #5 - Fine Forceps</td>
			<td>Fine Science Tools</td>
			<td>11254-20</td>
			<td></td>
		</tr>
		<tr>
			<td>Electrocautery</td>
			<td>Macan</td>
			<td>MV-7A</td>
			<td></td>
		</tr>
		<tr>
			<td>Endotracheal intubation kit</td>
			<td>Kent Scientific</td>
			<td>ETI-MSE</td>
			<td></td>
		</tr>
		<tr>
			<td>Forceps</td>
			<td>Fine Science Tools</td>
			<td>11027-12</td>
			<td></td>
		</tr>
		<tr>
			<td>Halsted-mosquito hemostat</td>
			<td>Roboz Surgical Instrument Co</td>
			<td>RS-7112</td>
			<td></td>
		</tr>
		<tr>
			<td>Heparin</td>
			<td>Fresnius Medical Care</td>
			<td>C504701</td>
			<td></td>
		</tr>
		<tr>
			<td>Insulin syringe</td>
			<td>Life Technologies</td>
			<td>B328446</td>
			<td></td>
		</tr>
		<tr>
			<td>Isoflurane</td>
			<td>Piramal Critical Care</td>
			<td>NDC 66794-017-25</td>
			<td></td>
		</tr>
		<tr>
			<td>Isopropyl Alcohol Swabs</td>
			<td>BD</td>
			<td>326895</td>
			<td></td>
		</tr>
		<tr>
			<td>Ketamine</td>
			<td>Hikma Pharmaceuticals PLC</td>
			<td>NDC 0413-9505-10</td>
			<td></td>
		</tr>
		<tr>
			<td>Dieffenbach Bulldog Clamp</td>
			<td>World Precision Instruments</td>
			<td>WPI14117</td>
			<td></td>
		</tr>
		<tr>
			<td>Needle holder/Forceps, Curved</td>
			<td>Micrins</td>
			<td>MI1542</td>
			<td></td>
		</tr>
		<tr>
			<td>Needle holder/Forceps, Straight</td>
			<td>Micrins</td>
			<td>MI1540</td>
			<td></td>
		</tr>
		<tr>
			<td>Perfadex Plus (Organ Preservation Solution)</td>
			<td>XVIVO Perfusion AB</td>
			<td>REF# 19950</td>
			<td></td>
		</tr>
		<tr>
			<td>PhysioSuite</td>
			<td>Kent Scientific</td>
			<td>PS-MSTAT-RT</td>
			<td>Used to check SpO2 and heartbeat</td>
		</tr>
		<tr>
			<td>Retractor</td>
			<td>Roboz Surgical Instrument Co</td>
			<td>RS-6560</td>
			<td></td>
		</tr>
		<tr>
			<td>Saline</td>
			<td>PP Pharmaceuticals LLC</td>
			<td>NDC 63323-186-10</td>
			<td></td>
		</tr>
		<tr>
			<td>Scissors</td>
			<td>Fine Science Tools</td>
			<td>14090-11</td>
			<td></td>
		</tr>
		<tr>
			<td>SomnoSuite Small Animal Anesthesia System</td>
			<td>Kent Scientific</td>
			<td>SS-MVG-Module</td>
			<td></td>
		</tr>
		<tr>
			<td>Sterile&#160; Cotton Gauze Pad</td>
			<td>Fisherbrand</td>
			<td>22-415-469</td>
			<td></td>
		</tr>
		<tr>
			<td>Surgical Microscope</td>
			<td>Leica</td>
			<td>M500-N w/ OHS</td>
			<td></td>
		</tr>
		<tr>
			<td>Syringe 5mL</td>
			<td>BD</td>
			<td>309646</td>
			<td></td>
		</tr>
		<tr>
			<td>Vannas-Tubingen Spring Scissors</td>
			<td>Fine Science Tools</td>
			<td>15008-08</td>
			<td></td>
		</tr>
		<tr>
			<td>Xylazine</td>
			<td>Korn Pharmaceuticals Corp</td>
			<td>NDC 59399-110-20</td>
			<td></td>
		</tr>
		<tr>
			<td>Yasargil Clamp</td>
			<td>Aesculap, Inc</td>
			<td>FT351T</td>
			<td>Used to clamp bronchus</td>
		</tr>
		<tr>
			<td>Yasargil Clamp</td>
			<td>Aesculap, Inc</td>
			<td>FT261T</td>
			<td>Used to clamp hilum</td>
		</tr>
		<tr>
			<td>Yasargil Clamp Applicator</td>
			<td>Aesculap, Inc</td>
			<td>FT484T</td>
			<td></td>
		</tr>
	</tbody>
</table>

a rat lung transplantation model of warm ischemia/reperfusion injury: optimizations to improve outcomes

From our experience with rat lung transplantation, we have found several areas for improvement. Information in the existing literature regarding methods for choosing appropriate cuff sizes for the pulmonary vein (PV), pulmonary artery (PA), or bronchus (Br) are varied, thus making the determination of proper cuff size during rat lung transplantation an exercise of trial and error. By standardizing the cuffing technique to use the smallest effective cuff appropriate for the size of the vessel or bronchus, one can make the transplantation procedure safer, faster, and more successful. Since diameters of the PV, PA, and Br are related to the body weight of the rat, we present a strategy to choosing an appropriate size using a weight-based guide. Since lung volume is also related to body weight, we recommend that this relationship should also be considered when choosing the proper volume of air for donor lung inflation during warm ischemia as well as for the proper volume of PBS to be instilled during bronchoalveolar lavage (BAL) fluid collection. We also describe methods for 4th intercostal space dissection, wound closure, and sample collection from both the native and transplanted lobes.

In order to measure pulmonary edema, the wet-to-dry weight ratio was calculated. The donor&#39;s native lobe, the transplanted lobe, and the recipient&#39;s native lobe were collected as described in the protocol and weighed immediately for wet weight, dried at 60 &#176;C for 48 h, and then weighed again for the dry weight. An increased wet-to-dry weight ratio would be indicative of pulmonary edema. Our results indicate that the transplanted lobe did have a significant increase in wet-to-dry ...

Watch this Scientific Journal Video about A Rat Lung Transplantation Model of Warm Ischemia/Reperfusion Injury: Optimizations to Improve Outcomes at JoVE.com

A Rat Lung Transplantation Model of Warm Ischemia/Reperfusion Injury: Optimizations to Improve Outcomes

Here, we present optimizations to a rat lung transplantation model that serve to improve outcomes. We provide a size guide for cuffs based on body weight, a measurement strategy to ascertain the 4th intercostal space, and methods of wound closure and BAL (bronchoalveolar lavage) fluid and tissue collection.

From our experience with rat lung transplantation, we have found several areas for improvement. Information in the existing literature regarding methods ...

This protocol identifies four key areas to help improve the methodology and have reliable lung transplantation. First is a reproducible cuffing technique. Second is accurately and reproducibly identifying the fourth intercostal space, a thorough closure of the wound, and then how to recover and obtain samples for analysis.These techniques help develop a reliable method of lung transplantation to work on molecular mechanisms and develop therapeutic interventions. Begin with the surgical device setup by turning on the heart rate/oxygen saturation monitoring equipment and warming up the board to 42 degrees Celsius. Also, turn on the ventilation and anesthesia machine to prewarm the isoflurane evaporator.Fill an anesthesia syringe with 10 milliliters of liquid isoflurane and mount the syringe onto the ventilation and anesthesia machine. Next, turn on the surgical microscope with the height and focus adjusted to the preferences and start the electrocautery device. Likewise, prepare and lay out the surgical tools.Determine the correct gauge size of the angio-catheter to be used to make the cuffs based on the body weight of the rat by referring to table one. After preparing the cuffs for the pulmonary artery, bronchus, and pulmonary vein, place the angio-catheter of the appropriate size on a sterile surface under the surgical microscope. Then, use a rib-back surgical blade number 11 to cut the angio-catheter to a 90 degree angle to form a two millimeter long cuff body with a one millimeter width and height at the top of the cuff body.After preparing the wrap for the surgery, make a three to four centimeter-long midline skin incision, mid neck, with the scissors, and carefully dissect out the subcutaneous tissues and muscles using forceps. For the endotracheal intubation, thread a 4-0 silk suture around the trachea. Then, insert 16 gauge angio-catheter into the trachea and tie the suture around the trachea tightly with a double knot, followed with a single knot to hold the angio-catheter in place.Connect the angio-catheter to the ventilator to maintain a surgical plane of anesthesia in the rat with 1 to 2%isoflurane. Use the scissors to perform a laparo-sternotomy, as a combined midline and transverse incision. Then, inject 1, 000 units per kilogram of heparin with an insulin syringe via the inferior vena cava, or IVC, and allow 10 minutes for systemic circulation.While the lungs are are ventilating, cut the right and left auricles with micro dissecting spring scissors and then introduce an 18 gauge angio-catheter through the pulmonary artery to gravity flush the lungs with 20 milliliters of preservation solution in a syringe hanging at 28 centimeters of water, connected to the tubing and angio-catheter. Disconnect the ventilator from the endotracheal tube to connect to a five milliliter syringe filled with a proper volume of air based on body weight. After one hour of the warm ischemia, excise the heart-lung block with the micro dissecting spring scissors and forceps and place on a sterile gauze dampened with ice cold PBS on a sterile Petri dish on ice.Carefully trim the left lung hilar area with Vannas-Tubingen spring scissor and procure the left pulmonary vein, pulmonary artery, and bronchus. Use a mosquito hemostat to grab the cuff tab. Then, take the distal end of the pulmonary vein, pulmonary artery, or bronchus through the appropriate cuff body and evert the extra tissue around the cuff before securing with 8-0 nylon suture.Once done, use Vannas-Tubingen spring scissors to trim the extra tissue and the cuff around the cuff body. To prepare the recipient rat, draw a line on the chest of the rat from the suprasternal notch to the xiphoid process. At the middle of this line, draw a line along the left side of the chest that measures half of the measurement from the suprasternal notch to the xiphoid process.Using the fiber optic cable connected to an LED light from the endotracheal intubation kit, visualize and intubate the recipient with a 16 gauge angio-catheter. Once the lungs are pulled out, place a sterile gauze around the left lung while holding it with Dieffenbach bulldog clamp and apply a Yasargil clamp on the left lung hilar area as proximally as possible. When the rat is prepared, proceed for the pulmonary vein anastomosis by placing 7-0 nylon suture around the recipient's pulmonary vein.Incise the recipient's pulmonary vein using the Vannas-Tubingen spring scissors by transversely cutting the upper and lower segmental veins as distally as possible, and flush out blood with 0.2 milliliters of one international unit per milliliter heparinized saline using an insulin syringe. Place the donor lung wrapped with an ice-cold, wet, sterile gauze into the thoracic cavity, and insert the donor's cuffed pulmonary vein into the recipient's pulmonary vein before securing the anastomosis with the prepositioned 7-0 nylon suture. For the bronchial or bronchus anastomosis, place a 7-0 nylon suture around the recipient's bronchus before incising the recipient's bronchus by transversely cutting the upper and lower segmental airways as distally as possible.After inserting the donor's cuffed bronchus into the recipient's bronchus, secure the anastomosis with the prepositioned 7-0 nylon suture. Next, perform the pulmonary artery anastomosis as described earlier. To allow the reprofusion and ventilation of the transplanted donor lung, remove the Yasargil clamp on the hilum, followed by closing the thoracotomy incision with a 6-0 nylon suture.Collect the BAL fluid from the native or transplanted lungs as desired. The wet to dry weight ratio of the lobes was calculated to measure the pulmonary edema. The transplanted lobe showed a significant increase in the wet to dry weight ratio compared to the donor's or recipient's native lobe, indicating no pulmonary edema.In our opinion, the two critical steps of this procedure are to one, accurately use anatomic landmarks to identify the fourth intercostal space, and then two, select and appropriately use the cuffs to have a reproducible cuffing technique. A rat lung transplantation model that is both reproducible and consistent is a basis for molecular investigations into ischemia reprofusion and transplantation in general.

a-rat-lung-transplantation-model-warm-ischemiareperfusion-injury

Research

JoVE Journal

Medicine

Normothermic Cardiac Arrest and Cardiopulmonary Resuscitation: A Mouse Model of Ischemia-Reperfusion Injury

Acute Kidney Injury (AKI) is a common, highly lethal, complication of critical illness which has a high mortality1-4 and which is most 
frequently caused by whole-body hypoperfusion.5,6 Successful reproduction of whole-body hypoperfusion in rodent models has been fraught with 
difficulty.7-9,9,10 Models which employ focal ischemia have repeatedly demonstrated results which do not translate to the clinical setting, and larger 
animal models which allow for whole body hypoperfusion lack access to the full toolset of genetic manipulation possible in the mouse.11,12 However, in recent 
years a mouse model of cardiac arrest and cardiopulmonary resuscitation has emerged which can be adapted to model AKI.13 This model reliably reproduces 
physiologic, functional, anatomic, and histologic outcomes seen in clinical AKI, is rapidly repeatable, and offers all of the significant advantages of a murine surgical 
model, including access to genetic manipulative techniques, low cost relative to large animals, and ease of use. Our group has developed extensive experience 
with use of this model to assess a number of organ-specific outcomes in AKI.14,15

A powerful model for perioperative and critical care related acute kidney injury is presented. Using whole body hypoperfusion induced by cardiac arrest it is possible to nearly replicate the histologic and functional changes of clinical AKI.

Acute Kidney Injury (AKI) is a common, highly lethal, complication of critical illness which has a high mortality1-4 and which is most 
frequently caused ...

Stem Cell Transplantation in an in vitro Simulated Ischemia/Reperfusion Model

Stem cell transplantation protocols are finding their way into clinical practice1,2,3. Getting better results, making the protocols more robust, and finding new sources for implantable cells are the focus of recent research4,5. Investigating the effectiveness of cell therapies is not an easy task and new tools are needed to investigate the mechanisms involved in the treatment process6. We designed an experimental protocol of ischemia/reperfusion in order to allow the observation of cellular connections and even subcellular mechanisms during ischemia/reperfusion injury and after stem cell transplantation and to evaluate the efficacy of cell therapy. H9c2 cardiomyoblast cells were placed onto cell culture plates7,8. Ischemia was simulated with 150 minutes in a glucose free medium with oxygen level below 0.5%. Then, normal media and oxygen levels were reintroduced to simulate reperfusion. After oxygen glucose deprivation, the damaged cells were treated with transplantation of labeled human bone marrow derived mesenchymal stem cells by adding them to the culture. Mesenchymal stem cells are preferred in clinical trials because they are easily accessible with minimal invasive surgery, easily expandable and autologous. After 24 hours of co-cultivation, cells were stained with calcein and ethidium-homodimer to differentiate between live and dead cells. This setup allowed us to investigate the intercellular connections using confocal fluorescent microscopy and to quantify the survival rate of postischemic cells by flow cytometry. Confocal microscopy showed the interactions of the two cell populations such as cell fusion and formation of intercellular nanotubes. Flow cytometry analysis revealed 3 clusters of damaged cells which can be plotted on a graph and analyzed statistically. These populations can be investigated separately and conclusions can be drawn on these data on the effectiveness of the simulated therapeutical approach.

Stem Cell Transplantation in an in vitro Simulated Ischemia/Reperfusion Model

We demonstrate how to set up an in vitro ischemia/reperfusion model and how to evaluate the effect of stem cell therapy on postischemic cardiac cells.

Stem cell transplantation protocols are finding their way into clinical practice1,2,3. Getting better results, making the protocols more robust, and ...

In situ Transverse Rectus Abdominis Myocutaneous Flap: A Rat Model of Myocutaneous Ischemia Reperfusion Injury

Free tissue transfer is the gold standard of reconstructive surgery to repair complex defects not amenable to local options or those requiring composite tissue. Ischemia reperfusion injury (IRI) is a known cause of partial free flap failure and has no effective treatment. Establishing a laboratory model of this injury can prove costly both financially as larger mammals are conventionally used and in the expertise required by the technical difficulty of these procedures typically requires employing an experienced microsurgeon. This publication and video demonstrate the effective use of a model of IRI in rats which does not require microsurgical expertise. This procedure is an in situ model of a transverse abdominis myocutaneous (TRAM) flap where atraumatic clamps are utilized to reproduce the ischemia-reperfusion injury associated with this surgery. A laser Doppler Imaging (LDI) scanner is employed to assess flap perfusion and the image processing software, Image J to assess percentage area skin survival as a primary outcome measure of injury.

In situ Transverse Rectus Abdominis Myocutaneous Flap: A Rat Model of Myocutaneous Ischemia Reperfusion Injury

Free tissue transfer is widely employed in reconstructive surgery to restore form and function following oncological resection and trauma. Preconditioning this tissue prior to surgery may improve outcome. This article describes an in situ transverse rectus abdominis myocutaneous flap (TRAM) in rats as a means for testing preconditioning strategies.

Free tissue transfer is the gold standard of reconstructive surgery to repair complex defects not amenable to local options or those requiring composite ...

Ischemia-reperfusion Model of Acute Kidney Injury and Post Injury Fibrosis in Mice

Ischemia-reperfusion induced acute kidney injury (IR-AKI) is widely used as a model of AKI in mice, but results are often quite variable with high, often unreported mortality rates that may confound analyses. Bilateral renal pedicle clamping is commonly used to induce IR-AKI, but differences between effective clamp pressures and/or renal responses to ischemia between kidneys often lead to more variable results. In addition, shorter clamp times are known to induce more variable tubular injury, and while mice undergoing bilateral injury with longer clamp times develop more consistent tubular injury, they often die within the first 3 days after injury due to severe renal insufficiency. To improve post-injury survival and obtain more consistent and predictable results, we have developed two models of unilateral ischemia-reperfusion injury followed by contralateral nephrectomy. Both surgeries are performed using a dorsal approach, reducing surgical stress resulting from ventral laparotomy, commonly used for mouse IR-AKI surgeries. For induction of moderate injury BALB/c mice undergo unilateral clamping of the renal pedicle for 26 min and also undergo simultaneous contralateral nephrectomy. Using this approach, 50-60% of mice develop moderate AKI 24 hr after injury but 90-100% of mice survive. To induce more severe AKI, BALB/c mice undergo renal pedicle clamping for 30 min followed by contralateral nephrectomy 8 days after injury. This allows functional assessment of renal recovery after injury with 90-100% survival. Early post-injury tubular damage as well as post injury fibrosis are highly consistent using this model.

We describe models of moderate and severe ischemia-reperfusion-induced kidney injury in which the mice undergo unilateral renal pedicle clamping followed by simultaneous or delayed contralateral nephrectomy, respectively. These models consistently give rise to renal dysfunction and post-injury fibrosis, but injury severity and survival are dependent on mouse background, age and surgical equipment.

Ischemia-reperfusion induced acute kidney injury (IR-AKI) is widely used as a model of AKI in mice, but results are often quite variable with high, often ...

A Murine Model of Myocardial Ischemia-reperfusion Injury through Ligation of the Left Anterior Descending Artery

Acute or chronic myocardial infarction (MI) are cardiovascular events resulting in high morbidity and mortality. Establishing the pathological mechanisms at work during MI and developing effective therapeutic approaches requires methodology to reproducibly simulate the clinical incidence and reflect the pathophysiological changes associated with MI. Here, we describe a surgical method to induce MI in mouse models that can be used for short-term ischemia-reperfusion (I/R) injury as well as permanent ligation. The major advantage of this method is to facilitate location of the left anterior descending artery (LAD) to allow for accurate ligation of this artery to induce ischemia in the left ventricle of the mouse heart. Accurate positioning of the ligature on the LAD increases reproducibility of infarct size and thus produces more reliable results. Greater precision in placement of the ligature will improve the standard surgical approaches to simulate MI in mice, thus reducing the number of experimental animals necessary for statistically relevant studies and improving our understanding of the mechanisms producing cardiac dysfunction following MI. This mouse model of MI is also useful for the preclinical testing of treatments targeting myocardial damage following MI.

We introduce a surgical method to induce experimental ischemia/reperfusion (I/R) injury to simulate myocardial infarction (MI) in mouse models that allows for more clarity in positioning of the ligation on the left anterior descending artery (LAD) to increase the reproducibility of MI experiments in mice.

Acute or chronic myocardial infarction (MI) are cardiovascular events resulting in high morbidity and mortality. Establishing the pathological mechanisms ...

Method of Isolated Ex Vivo Lung Perfusion in a Rat Model: Lessons Learned from Developing a Rat EVLP Program

The number of acceptable donor lungs available for lung transplantation is severely limited due to poor quality. Ex-Vivo Lung Perfusion (EVLP) has allowed lung transplantation in humans to become more readily available by enabling the ability to assess organs and expand the donor pool. As this technology expands and improves, the ability to potentially evaluate and improve the quality of substandard lungs prior to transplant is a critical need. In order to more rigorously evaluate these approaches, a reproducible animal model needs to be established that would allow for testing of improved techniques and management of the donated lungs as well as to the lung-transplant recipient. In addition, an EVLP animal model of associated pathologies, e.g., ventilation induced lung injury (VILI), would provide a novel method to evaluate treatments for these pathologies. Here, we describe the development of a rat EVLP lung program and refinements to this method that allow for a reproducible model for future expansion. We also describe the application of this EVLP system to model VILI in rat lungs. The goal is to provide the research community with key information and &#8220;pearls of wisdom&#8221;/techniques that arose from trial and error and are critical to establishing an EVLP system that is robust and reproducible.

Method of Isolated Ex Vivo Lung Perfusion in a Rat Model: Lessons Learned from Developing a Rat EVLP Program

Ex-Vivo Lung Perfusion (EVLP) has allowed lung transplantation in humans to become more readily available by enabling the ability to assess organs and expand the donor pool. Here, we describe the development of a rat EVLP program and refinements that allow for a reproducible model for future expansion.

The number of acceptable donor lungs available for lung transplantation is severely limited due to poor quality. Ex-Vivo Lung Perfusion (EVLP) has allowed ...

Induction and Assessment of Ischemia-reperfusion Injury in Langendorff-perfused Rat Hearts

The biochemical events surrounding ischemia reperfusion injury in the acute setting are of great importance to furthering novel treatment options for myocardial infarction and cardiac complications of thoracic surgery. The ability of certain drugs to precondition the myocardium against ischemia reperfusion injury has led to multiple clinical trials, with little success. The isolated heart model allows acute observation of the functional effects of ischemia reperfusion injury in real time, including the effects of various pharmacological interventions administered at any time-point before or within the ischemia-reperfusion injury window. Since brief periods of ischemia can precondition the heart against ischemic injury, in situ aortic cannulation is performed to allow for functional assessment of non-preconditioned myocardium. A saline filled balloon is placed into the left ventricle to allow for real-time measurement of pressure generation. Ischemic injury is simulated by the cessation of perfusion buffer flow, followed by reperfusion. The duration of both ischemia and reperfusion can be modulated to examine biochemical events at any given time-point. Although the Langendorff isolated heart model does not allow for the consideration of systemic events affecting ischemia and reperfusion, it is an excellent model for the examination of acute functional and biochemical events within the window of ischemia reperfusion injury as well as the effect of pharmacological intervention on cardiac pre- and postconditioning. The goal of this protocol is to demonstrate how to perform in situ aortic cannulation and heart excision followed by ischemia/reperfusion injury in the Langendorff model.

The isolated rat heart is an enduring model for ischemia reperfusion injury. Here, we describe the process of harvesting the beating heart from a rat via in situ aortic cannulation, Langendorff perfusion of the heart, simulated ischemia-reperfusion injury, and infarct staining to confirm the extent of ischemic insult.

The biochemical events surrounding ischemia reperfusion injury in the acute setting are of great importance to furthering novel treatment options for ...

Murine Model of Intestinal Ischemia-reperfusion Injury

Intestinal ischemia is a life-threatening condition associated with a broad range of clinical conditions including atherosclerosis, thrombosis, hypotension, necrotizing enterocolitis, bowel transplantation, trauma and chronic inflammation. Intestinal ischemia-reperfusion (IR) injury is a consequence of acute mesenteric ischemia, caused by inadequate blood flow through the mesenteric vessels, resulting in intestinal damage. Reperfusion following ischemia can further exacerbate damage of the intestine. The mechanisms of IR injury are complex and poorly understood. Therefore, experimental small animal models are critical for understanding the pathophysiology of IR injury and the development of novel therapies.
Here we describe a mouse model of acute intestinal IR injury that provides reproducible injury of the small intestine without mortality. This is achieved by inducing ischemia in the region of the distal ileum by temporally occluding the peripheral and terminal collateral branches of the superior mesenteric artery for 60 min using microvascular clips. Reperfusion for 1 hr, or 2 hr after injury results in reproducible injury of the intestine examined by histological analysis. Proper position of the microvascular clips is critical for the procedure. Therefore the video clip provides a detailed visual step-by-step description of this technique. This model of intestinal IR injury can be utilized to study the cellular and molecular mechanisms of injury and regeneration.

Here we describe the detailed procedure of intestinal ischemia-reperfusion in mice which results in reproducible injury without mortality to encourage the standardization of this technique across the field. This model of intestinal ischemia-reperfusion injury can be utilized to study the cellular and molecular mechanisms of injury and regeneration.

Intestinal ischemia is a life-threatening condition associated with a broad range of clinical conditions including atherosclerosis, thrombosis, ...

A Mouse Model of Retinal Ischemia-Reperfusion Injury Through Elevation of Intraocular Pressure

Retinal ischemia-reperfusion (I/R) is a pathophysiological process contributing to cellular damage in multiple ocular conditions, including glaucoma, diabetic retinopathy, and retinal vascular occlusions. Rodent models of I/R injury are providing significant insights into mechanisms and treatment strategies for human I/R injury, especially with regard to neurodegenerative damage in the retinal neurovascular unit. Presented here is a protocol for inducing retinal I/R injury in mice through elevation of intraocular pressure (IOP). In this protocol, the ocular anterior chamber is cannulated with a needle, through which flows the drip of an elevated saline reservoir. Using this drip to raise IOP above systolic arterial blood pressure, a practitioner temporarily halts inner retinal blood flow (ischemia). When circulation is reinstated (reperfusion) by removal of the cannula, severe cellular damage ensues, resulting ultimately in retinal neurodegeneration. Recent studies demonstrate inflammation, vascular permeability, and capillary degeneration as additional elements of this model. Compared to alternative retinal I/R methodologies, such as retinal arterial ligation, retinal I/R injury by elevated IOP offers advantages in its&#160;anatomical specificity, experimental tractability, and technical accessibility, presenting itself as a valuable tool for examining neuronal pathogenesis and therapy in the retinal neurovascular unit.

This article describes a procedure for inducing retinal ischemia-reperfusion injury by elevated intraocular pressure in mice. Retinal ischemia-reperfusion injury by elevated intraocular pressure serves to model human pathologies characterized by compromised oxygen and nutrient delivery in the retina, enabling researchers to examine potential cellular mechanisms and treatments for human diseases of the retinal neurovascular unit.

Retinal ischemia-reperfusion (I/R) is a pathophysiological process contributing to cellular damage in multiple ocular conditions, including glaucoma, ...

A Pre-clinical Rat Model for the Study of Ischemia-reperfusion Injury in Reconstructive Microsurgery

Ischemia-reperfusion injury is the main cause of flap failure in reconstructive microsurgery. The rat is the preferred preclinical animal model in many areas of biomedical research due to its cost-effectiveness and its translation to humans. This protocol describes a method to create a preclinical free skin flap model in rats with ischemia-reperfusion injury. The described 3 cm x 6 cm rat free skin flap model is easily obtained after the placement of several vascular ligatures and the section of the vascular pedicle. Then, 8 h after the ischemic insult and completion of the microsurgical anastomosis, the free skin flap develops the tissue damage. These ischemia-reperfusion injury-related damages can be studied in this model, making it a suitable model for evaluating therapeutic agents to address this pathophysiological process. Furthermore, two main monitoring techniques are described in the protocol for the assessment of this animal model: transit-time ultrasound technology and laser speckle contrast analysis.

Here, we describe a pre-clinical animal model for studying the pathophysiology of ischemia-reperfusion injury in reconstructive microsurgery. This free skin flap model based on the superficial caudal epigastric vessels in the rat may also allow for the evaluation of different therapies and compounds to counteract ischemia-reperfusion injury-related damage.

Ischemia-reperfusion injury is the main cause of flap failure in reconstructive microsurgery. The rat is the preferred preclinical animal model in many ...