Name: 2-vessel occlusion/hypotension: a rat model of global brain ischemia
Uploaded: 2013-06-22T13:00:00
Description: Watch this Scientific Journal Video about 2-Vessel Occlusion/Hypotension: A Rat Model of Global Brain Ischemia at JoVE.com

1. Preparation
All animal experiments must conform to institutional guidelines and receive approval by a respective animal care committee prior to initiation. All procedures presented here have been approved by the Wayne State University Institutional Animal Care and Use Committee and follow the guidelines on the ethical treatment of animals as put forth in the Guide for the Care and Use of Laboratory Animals and to the US Government Principles for the Utilization and Care of Vertebrate Animals ...

<ol>
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B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Death+by+design:+apoptosis,+necrosis+and+autophagy.">Death by design: apoptosis, necrosis and autophagy.</a> Current Opinion in Cell Biology. 16, 663-669 (2004).</li><li>Kirino, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Delayed+neuronal+death+in+the+gerbil+hippocampus+following+ischemia.">Delayed neuronal death in the gerbil hippocampus following ischemia.</a> Brain Research. 239, 57-69 (1982).</li><li>Yager, J. Y., Brucklacher, R. M., Vannucci, R. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cerebral+energy+metabolism+during+hypoxia-ischemia+and+early+recovery+in+immature+rats.">Cerebral energy metabolism during hypoxia-ischemia and early recovery in immature rats.</a> The American Journal of Physiology. 262, 672-677 (1992).</li><li>Sugawara, T., Fujimura, M., Morita-Fujimura, Y., Kawase, M., Chan, P. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mitochondrial+release+of+cytochrome+c+corresponds+to+the+selective+vulnerability+of+hippocampal+CA1+neurons+in+rats+after+transient+global+cerebral+ischemia.">Mitochondrial release of cytochrome c corresponds to the selective vulnerability of hippocampal CA1 neurons in rats after transient global cerebral ischemia.</a> J. Neurosci. 19, RC39 (1999).</li><li>Nishino, H., 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=Pathophysiological+process+after+transient+ischemia+of+the+middle+cerebral+artery+in+the+rat.">Pathophysiological process after transient ischemia of the middle cerebral artery in the rat.</a> Brain Research Bulletin. 35, 51-56 (1994).</li><li>Ross, D. T., Ebner, F. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thalamic+retrograde+degeneration+following+cortical+injury:+an+excitotoxic+process.">Thalamic retrograde degeneration following cortical injury: an excitotoxic process.</a> Neuroscience. 35, 525-550 (1990).</li><li>Soriano, M. A., Ferrer, I., Rodriguez-Farre, E., Planas, A. 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T., Klatzo, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experimental+cerebral+ischemia+in+mongolian+gerbils.+I.+Light+microscopic+observations.">Experimental cerebral ischemia in mongolian gerbils. I. Light microscopic observations.</a> Acta Neuropathologica. 32, 209-223 (1975).</li><li>Saver, J. L., Albers, G. W., Dunn, B., Johnston, K. C., Fisher, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stroke+Therapy+Academic+Industry+Roundtable+(STAIR)+recommendations+for+extended+window+acute+stroke+therapy+trials.">Stroke Therapy Academic Industry Roundtable (STAIR) recommendations for extended window acute stroke therapy trials.</a> Stroke; a Journal of Cerebral Circulation. 40, 2594-2600 (2009).</li><li>Busto, R., Dietrich, W. D., Globus, M. Y., Ginsberg, M. 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The model described here produces an ischemic insult to the brain that can occur as a result of cardiac arrest and resuscitation, providing an injury similar to that found in humans. This method for producing global brain ischemia is one of multiple protocols. We utilize this protocol foremost for its comparably low mortality rate, rapid recovery, and reproducible results. The cardiac arrest/resuscitation model is arguably the most clinically relevant model, however technically the most difficult to constantly rep...

Brain damage as a consequence of cardiac arrest and stroke is a leading cause of death and long-term disability. While cardiopulmonary resuscitation for victims of cardiac arrest succeeds in restoring spontaneous circulation in about 70,000 patients per year in the US 7,8 at least 60% of these patients subsequently die in the hospital as a result of extensive brain damage and only 3-10% of resuscitated patients can resume their former lifestyles 9,10 . Clearly, understanding the mechanisms that lead to brain damage following global brain ischemia and designing therapeutic interventions to minimize neurologic trauma is of critical importance.
Brain ischemia can be modeled utilizing multiple methods. Most commonly, brain ischemia is produced in the rodent by occluding a major blood vessel in the brain, the middle cerebral artery, thus producing a focal ischemic stroke 11,12 . While clinically important, focal brain ischemia is not an accurate method to study brain damage produced by cardiac arrest/resuscitation. To model this clinical paradigm the entire brain must be made ischemic followed by reintroduction of blood flow. To closely mimic this clinical presentation, investigators experimentally induce cardiac arrest followed by resuscitation with CPR and defibrillation 13,14 . This model is clinically relevant, however unpredictable resuscitation times can increase variability and may make data analysis difficult to interpret. Additionally, this model is associated with a high mortality rate, further increasing animal number necessary to test a hypothesis. Investigating the cerebral response to global ischemia and/or reperfusion in a more reproducible, consistent, and survivable insult may be preferred.
Global ischemia can be induced in the brain while preserving some blood flow systemically. This reduces mortality, while allowing investigation of the mechanisms of tissue damage in the brain 2. To produce global brain ischemia, it is necessary to interrupt or greatly limit flow in all four vessels that supply the brain, the internal carotid arteries and vertebral arteries. These vessels supply the brain with blood flow through a vascular structure called the Circle of Willis, which forms an anastomotic loop. This vascular architecture allows the brain to retain perfusion in the event of proximal vascular occlusion. Therefore, to induce complete ischemia of the brain, blood flow through all contributory vessels must occur. Carotid artery occlusion can be accomplished using a minimally invasive ventral neck cut-down and application of aneurism clips for a desired period. Interruption of blood flow via the vertebral arteries can be difficult, as they are incased in the transverse foramina of the vertebral column. Investigators have addressed this by electrocauterizing the vertebral arteries 24-48 hr prior to carotid occlusion and brain ischemia (4VO model) 15. In contrast to this approach, Smith, et al. developed a method of inducing global brain ischemia by reducing mean arterial blood pressure (MAP) systemically to 40 mmHg to reduce perfusion through the vertebral arteries to a point where blood flow is lost or greatly reduced 2. When coupled with carotid occlusion, this method produces ischemia throughout the forebrain, resulting in a pattern of brain damage that closely mimics that of cardiac arrest survivors. In a further refinement of this method, the model we present here requires tight MAP regulation at 30 mmHg &plusmn; 1mHg during the entire 8 min of ischemia. We found this alteration improves the reproducibility of brain damage induced by this model while preserving the low mortality rate of the original technique designed by Smith et al.
The precise phenotype of cell death and overall extent of tissue damage caused by the model presented here are directly dependent on ischemic duration 16. Following 8 min of ischemia, CA1 neurons exhibit delayed cell death, suggesting that there is a temporal window for therapeutic intervention during the reperfusion phase 15,17 . At the onset of reperfusion, neurons quickly regain function and no immediate cell death is detectable 18. However this insult causes induction of cell death cascades (apoptosis) that culminate in release of apoptogenic proteins from mitochondria, including cytochrome c, between 4-6 hr of reperfusion 3,19. Between 6 and 24 hr of reperfusion, neurons of the CA1 hippocampus have committed to cell demise, and the apoptotic cell death program is executed 19. It should be noted that cell death phenotype responsible for ischemic injury is highly controversial. Early studies have suggested necrosis is the primary cell death phenotype 20,21 , while other others report apoptosis as the principal mechanism 22,23 . In total, current evidence suggest that cells die of a spectrum of cell death phenotypes ranging from classic apoptosis to necrosis. The specific mode of cell death is dependent on many factors, with the degree of contribution of each phenotype depending on the severity of the insult, amongst other factors 24,25. By 24 hr of reperfusion, dying cells possess pyknotic nuclei, condensed cytosol with clear evidence of aggregated cellular contents, and loss of functional mitochondrial morphology. Dead cells are further broken down, engulfed by immune cells such as macrophages and/or microglia, and cleared from the CA1 hippocampal region. By 4-7 days of reperfusion, dead cells are removed, and all that remains are inflammatory cells and activated glial cells 17,26 . Therefore, 7 days of reperfusion represents an optimal time where CA1 hippocampal neuronal death can be quantified using simple, non-specific cell stains including Cresyl violet or hemotoxylin-eosin and counted based on morphologic inclusion criteria. Cells remaining at this late reperfusion interval can be counted as surviving cells, thus providing an index of brain damage.
If this model is to be utilized to test therapeutic interventions, it is suggested that the experimental design follow STAIR criteria (Stroke Therapy Academic Industry Roundtable) 27. These guidelines should be followed when designing and conducting a study, however are not discussed here.

<table border="1">
 <tbody>
 <tr>
 <td></td>
 <td></td>
 <td></td>
 <td>Material Name</td>
 </tr>
 <tr>
 <td>5-0 VICRYL suture, reverse cutting </td>
 <td>Ethicon</td>
 <td>J391H</td>
 <td></td>
 </tr>
 <tr>
 <td>Scalpel, No.10</td>
 <td>Swann-Morton</td>
 <td>6601</td>
 <td></td>
 </tr>
 <tr>
 <td>Gauze Sponges</td>
 <td>Fisher</td>
 <td>22-362-178</td>
 <td></td>
 </tr>
 <tr>
 <td>18G x 1 &frac12; in needle</td>
 <td>BD</td>
 <td>305201</td>
 <td></td>
 </tr>
 <tr>
 <td>23G x 1 in needle</td>
 <td>BD</td>
 <td>305145</td>
 <td></td>
 </tr>
 <tr>
 <td>26 G x 3/8 in needle</td>
 <td>BD</td>
 <td>305110</td>
 <td></td>
 </tr>
 <tr>
 <td>18 G x 1 &frac14; catheter</td>
 <td>EXEL</td>
 <td>26735</td>
 <td></td>
 </tr>
 <tr>
 <td>1 ml syringe</td>
 <td>BD</td>
 <td>309659</td>
 <td></td>
 </tr>
 <tr>
 <td>10 ml syringe</td>
 <td>BD</td>
 <td>309604</td>
 <td></td>
 </tr>
 <tr>
 <td>60 ml syringe</td>
 <td>BD</td>
 <td>309653</td>
 <td></td>
 </tr>
 <tr>
 <td>Surgilube</td>
 <td>Henry Schein</td>
 <td>1152666</td>
 <td></td>
 </tr>
 <tr>
 <td>.9% Saline, plastic IV bag</td>
 <td>Henry Schein</td>
 <td>1537468</td>
 <td></td>
 </tr>
 <tr>
 <td>Suture 3-0 Silk</td>
 <td>Henry Schein</td>
 <td>1007842</td>
 <td></td>
 </tr>
 <tr>
 <td>Puralube Ophthalmic Ointment</td>
 <td>Henry Schein</td>
 <td>3390017</td>
 <td></td>
 </tr>
 <tr>
 <td>Betadine</td>
 <td>Henry Schein</td>
 <td>6903564</td>
 <td></td>
 </tr>
 <tr>
 <td>Sterile Towel Drape</td>
 <td>Moore Medical</td>
 <td>14170</td>
 <td></td>
 </tr>
 <tr>
 <td>Polyethylene Tubing, 50</td>
 <td>Intramedic</td>
 <td>427411</td>
 <td></td>
 </tr>
 <tr>
 <td>Stopcock, 3 way</td>
 <td>Smiths medical</td>
 <td>MX9311L</td>
 <td></td>
 </tr>
 <tr>
 <td></td>
 <td></td>
 <td></td>
 <td>Drug Name</td>
 </tr>
 <tr>
 <td>AERRANE (isoflurane)</td>
 <td>Henry Schein</td>
 <td>2091966</td>
 <td></td>
 </tr>
 <tr>
 <td>Mapap Liquid (Tylenol)</td>
 <td>Major Pharmaceuticals</td>
 <td>1556</td>
 <td></td>
 </tr>
 <tr>
 <td>Kedavet (ketamine)</td>
 <td>Ketathesia Butney</td>
 <td>NDC 50989-996-06</td>
 <td></td>
 </tr>
 <tr>
 <td>Butorphic (butorphanol)</td>
 <td>Lloyd Labs</td>
 <td>4881</td>
 <td></td>
 </tr>
 <tr>
 <td>Heparin</td>
 <td>APP Pharmaceuticals</td>
 <td>504011</td>
 <td></td>
 </tr>
 <tr>
 <td></td>
 <td></td>
 <td></td>
 <td>Chemical Name </td>
 </tr>
 <tr>
 <td>Paraformaldehyde prills</td>
 <td>Elecron Microscopy Sci.</td>
 <td>19202</td>
 <td></td>
 </tr>
 <tr>
 <td>2-methylbutane</td>
 <td>Sigma</td>
 <td>270342</td>
 <td></td>
 </tr>
 <tr>
 <td>Cresyl Violet Acetate</td>
 <td>Sigma</td>
 <td>C5042</td>
 <td></td>
 </tr>
 <tr>
 <td>Sucrose</td>
 <td>Sigma</td>
 <td>S9378</td>
 <td></td>
 </tr>
 <tr>
 <td></td>
 <td></td>
 <td></td>
 <td>Software</td>
 </tr>
 <tr>
 <td>ImageJ</td>
 <td>NIH</td>
 <td></td>
 <td></td>
 </tr>
 </tbody>
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2-vessel occlusion/hypotension: a rat model of global brain ischemia

Cardiac arrest followed by resuscitation often results in dramatic brain damage caused by ischemia and subsequent reperfusion of the brain. Global brain ischemia produces damage to specific brain regions shown to be highly sensitive to ischemia 1. Hippocampal neurons have higher sensitivity to ischemic insults compared to other cell populations, and specifically, the CA1 region of the hippocampus is particularly vulnerable to ischemia/reperfusion 2.
The design of therapeutic interventions, or study of mechanisms involved in cerebral damage, requires a model that produces damage similar to the clinical condition and in a reproducible manner. Bilateral carotid vessel occlusion with hypotension (2VOH) is a model that produces reversible forebrain ischemia, emulating the cerebral events that can occur during cardiac arrest and resuscitation. We describe a model modified from Smith et al. (1984) 2, as first presented in its current form in Sanderson, et al. (2008) 3, which produces reproducible injury to selectively vulnerable brain regions 3-6. The reliability of this model is dictated by precise control of systemic blood pressure during applied hypotension, the duration of ischemia, close temperature control, a specific anesthesia regimen, and diligent post-operative care. An 8-minute ischemic insult produces cell death of CA1 hippocampal neurons that progresses over the course of 6 to 24 hr of reperfusion, while less vulnerable brain regions are spared. This progressive cell death is easily quantified after 7-14 days of reperfusion, as a near complete loss of CA1 neurons is evident at this time.
In addition to this brain injury model, we present a method for CA1 damage quantification using a simple, yet thorough, methodology. Importantly, quantification can be accomplished using a simple camera-mounted microscope, and a free ImageJ (NIH) software plugin, obviating the need for cost-prohibitive stereology software programs and a motorized microscopic stage for damage assessment.

The 2VOH model of global brain ischemia/reperfusion causes neuronal death in the CA1 region of the hippocampus. Figure 2 represents the injury produced by 8 min of global brain ischemia, processed 14 days after reperfusion. Figures 2A and 2B compare the hippocampi from sham and post-ischemic brains, stained with Cresyl violet. Figure 2A shows a hippocampus from a sham-operated rat which exhibits normal morphology, including an intact CA1. Figure ...

Watch this Scientific Journal Video about 2-Vessel Occlusion/Hypotension: A Rat Model of Global Brain Ischemia at JoVE.com

2-Vessel Occlusion/Hypotension: A Rat Model of Global Brain Ischemia

Bilateral carotid occlusion coupled with systemic hypotension produces global brain ischemia in the rat, resulting in damage to the hippocampus with reproducible severity. Animal subjects are impaired with predictable patterns of brain damage, they recover expediently, and mortality rates are comparatively low.

Cardiac arrest followed by resuscitation often results in dramatic brain damage caused by ischemia and subsequent reperfusion of the brain. Global brain ...

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Medicine

MRI-guided Disruption of the Blood-brain Barrier using Transcranial Focused Ultrasound in a Rat Model

Focused ultrasound (FUS) disruption of the blood-brain barrier (BBB) is an increasingly investigated technique for circumventing the BBB1-5. The BBB is a significant obstacle to pharmaceutical treatments of brain disorders as it limits the passage of molecules from the vasculature into the brain tissue to molecules less than approximately 500 Da in size6. FUS induced BBB disruption (BBBD) is temporary and reversible4 and has an advantage over chemical means of inducing BBBD by being highly localized. FUS induced BBBD provides a means for investigating the effects of a wide range of therapeutic agents on the brain, which would not otherwise be deliverable to the tissue in sufficient concentration. While a wide range of ultrasound parameters have proven successful at disrupting the BBB2,5,7, there are several critical steps in the experimental procedure to ensure successful disruption with accurate targeting. This protocol outlines how to achieve MRI-guided FUS induced BBBD in a rat model, with a focus on the critical animal preparation and microbubble handling steps of the experiment.

Microbubble-mediated focused ultrasound disruption of the blood-brain barrier (BBB) is a promising technique for non-invasive targeted drug delivery in the brain1-3. This protocol outlines the experimental procedure for MRI-guided transcranial BBB disruption in a rat model.

Focused ultrasound (FUS) disruption of the blood-brain barrier (BBB) is an increasingly investigated technique for circumventing the BBB1-5. The BBB is a ...

A Murine Closed-chest Model of Myocardial Ischemia and Reperfusion

Surgical trauma by thoracotomy in open-chest models of coronary ligation induces an immune response which modifies different mechanisms involved in ischemia and reperfusion. Immune response includes cytokine expression and release or secretion of endogenous ligands of innate immune receptors. Activation of innate immunity can potentially modulate infarct size. We have modified an existing murine closed-chest model using hanging weights which could be useful for studying myocardial pre- and postconditioning and the role of innate immunity in myocardial ischemia and reperfusion. This model allows animals to recover from surgical trauma before onset of myocardial ischemia.
Volatile anesthetics have been intensely studied and their preconditioning effect for the ischemic heart is well known. However, this protective effect precludes its use in open chest models of coronary artery ligation. Thus, another advantage could be the use of the well controllable volatile anesthetics for instrumentation in a chronic closed-chest model, since their preconditioning effect lasts up to 72 hours. Chronic heart diseases with intermittent ischemia and multiple hit models are other possible applications of this model.
For the chronic closed-chest model, intubated and ventilated mice undergo a lateral blunt thoracotomy via the 4th intercostal space. Following identification of the left anterior descending a ligature is passed underneath the vessel and both suture ends are threaded through an occluder. Then, both suture ends are passed through the chest wall, knotted to form a loop and left in the subcutaneous tissue. After chest closure and recovery for 5 days, mice are anesthetized again, chest skin is reopened and hanging weights are hooked up to the loop under ECG control.
At the end of the ischemia/reperfusion protocol, hearts can be stained with TTC for infarct size assessment or undergo perfusion fixation to allow morphometric studies in addition to histology and immunohistochemistry.

Surgical trauma induces an inflammatory response. Cytokines and endogenous ligands are known to modulate myocardial infarct size following ischemia and reperfusion. We present a modified closed-chest model of murine ischemia and reperfusion using hanging weights to minimize effects of thoracotomy.

Surgical trauma by thoracotomy in open-chest models of coronary ligation induces an immune response which modifies different mechanisms involved in ...

Rat Model of Blood-brain Barrier Disruption to Allow Targeted Neurovascular Therapeutics

Endothelial cells with tight junctions along with the basement membrane and astrocyte end feet surround cerebral blood vessels to form the blood-brain barrier1. The barrier selectively excludes molecules from crossing between the blood and the brain based upon their size and charge. This function can impede the delivery of therapeutics for neurological disorders. A number of chemotherapeutic drugs, for example, will not effectively cross the blood-brain barrier to reach tumor cells2. Thus, improving the delivery of drugs across the blood-brain barrier is an area of interest.
The most prevalent methods for enhancing the delivery of drugs to the brain are direct cerebral infusion and blood-brain barrier disruption3. Direct intracerebral infusion guarantees that therapies reach the brain; however, this method has a limited ability to disperse the drug4. Blood-brain barrier disruption (BBBD) allows drugs to flow directly from the circulatory system into the brain and thus more effectively reach dispersed tumor cells. Three methods of barrier disruption include osmotic barrier disruption, pharmacological barrier disruption, and focused ultrasound with microbubbles. Osmotic disruption, pioneered by Neuwelt, uses a hypertonic solution of 25% mannitol that dehydrates the cells of the blood-brain barrier causing them to shrink and disrupt their tight junctions. Barrier disruption can also be accomplished pharmacologically with vasoactive compounds such as histamine5 and bradykinin6. This method, however, is selective primarily for the brain-tumor barrier7. Additionally, RMP-7, an analog of the peptide bradykinin, was found to be inferior when compared head-to-head with osmotic BBBD with 25% mannitol8. Another method, focused ultrasound (FUS) in conjunction with microbubble ultrasound contrast agents, has also been shown to reversibly open the blood-brain barrier9. In comparison to FUS, though, 25% mannitol has a longer history of safety in human patients that makes it a proven tool for translational research10-12.
In order to accomplish BBBD, mannitol must be delivered at a high rate directly into the brain's arterial circulation. In humans, an endovascular catheter is guided to the brain where rapid, direct flow can be accomplished. This protocol models human BBBD as closely as possible. Following a cut-down to the bifurcation of the common carotid artery, a catheter is inserted retrograde into the ECA and used to deliver mannitol directly into the internal carotid artery (ICA) circulation. Propofol and N2O anesthesia are used for their ability to maximize the effectiveness of barrier disruption13. If executed properly, this procedure has the ability to safely, effectively, and reversibly open the blood-brain barrier and improve the delivery of drugs that do not ordinarily reach the brain 8,13,14.

Blood-brain barrier disruption aids the delivery of certain drugs to the brain. Mannitol delivered intra-arterially shrinks cells surrounding blood vessels in order to physically disrupt the barrier.

Endothelial cells with tight junctions along with the basement membrane and astrocyte end feet surround cerebral blood vessels to form the blood-brain ...

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 ...

Oxygen-Glucose Deprivation and Reoxygenation as an In Vitro Ischemia-Reperfusion Injury Model for Studying Blood-Brain Barrier Dysfunction

Ischemia-Reperfusion (IR) injury is known to contribute significantly to the morbidity and mortality associated with ischemic strokes. Ischemic cerebrovascular accidents account for 80% of all strokes. A common cause of IR injury is the rapid inflow of fluids following an acute/chronic occlusion of blood, nutrients, oxygen to the tissue triggering the formation of free radicals.
Ischemic stroke is followed by blood-brain barrier (BBB) dysfunction and vasogenic brain edema. Structurally, tight junctions (TJs) between the endothelial cells play an important role in maintaining the integrity of the blood-brain barrier (BBB). IR injury is an early secondary injury leading to a non-specific, inflammatory response. Oxidative and metabolic stress following inflammation triggers secondary brain damage including BBB permeability and disruption of tight junction (TJ) integrity.
Our protocol presents an in vitro example of oxygen-glucose deprivation and reoxygenation (OGD-R) on rat brain endothelial cell TJ integrity and stress fiber formation. Currently, several experimental in vivo models are used to study the effects of IR injury; however they have several limitations, such as the technical challenges in performing surgeries, gene dependent molecular influences and difficulty in studying mechanistic relationships. However, in vitro models may aid in overcoming many of those limitations. The presented protocol can be used to study the various molecular mechanisms and mechanistic relationships to provide potential therapeutic strategies. However, the results of in vitro studies may differ from standard in vivo studies and should be interpreted with caution.

Oxygen-Glucose Deprivation and Reoxygenation as an In Vitro Ischemia-Reperfusion Injury Model for Studying Blood-Brain Barrier Dysfunction

Ischemia-Reperfusion (IR) injury is associated with a high rate of morbidity and mortality. The goal of the in vitro model of oxygen-glucose deprivation and reoxygenation (OGD-R) described here is to assess the effects of ischemia reperfusion injury on a variety of cells, particularly in blood-brain barrier (BBB) endothelial cells.

Ischemia-Reperfusion (IR) injury is known to contribute significantly to the morbidity and mortality associated with ischemic strokes. Ischemic ...

A Thrombotic Stroke Model Based On Transient Cerebral Hypoxia-ischemia

Stroke research has endured many setbacks in translating neuroprotective therapies into clinical practice. In contrast, the real-world therapy (tPA thrombolysis) rarely produces benefits in mechanical occlusion-based experimental models, which dominate preclinical stroke research. This split between the bench and bedside suggests the need to employ tPA-responsive models in preclinical stroke research. To this end, a simple and tPA-reactive thrombotic stroke model is invented and described here. This model consists of transient occlusion of the unilateral common carotid artery and delivery of 7.5% oxygen through a face mask in adult mice for 30 min, while maintaining the animal rectal temperature at 37.5 &#177; 0.5 &#176;C. Although reversible ligation of the unilateral carotid artery or hypoxia each suppressed cerebral blood flow only transiently, the combination of both insults caused lasting reperfusion deficits, fibrin and platelet deposition, and large infarct in the middle cerebral artery-supplied territory. Importantly, tail-vein injection of recombinant tPA at 0.5, 1, or 4 hr post-tHI (10 mg/kg) provided time-dependent reduction of the mortality rate and infarct size. This new stroke model is simple and can be standardized across laboratories to compare experimental results. Further, it induces thrombosis without craniectomy or introducing pre-formed emboli. Given these unique merits, the tHI model is a useful addition to the repertoire of preclinical stroke research.

Thromboembolic stroke models are vital tools for optimizing the recanalization therapy. Here we report a murine thrombotic stroke model based on transient cerebral hypoxic-ischemic (tHI) insult, which triggers thrombosis and infarction, and responds favorably to tissue plasminogen activator (tPA)-mediated fibrinolysis in a therapeutic window similar to those in stroke patients.

Stroke research has endured many setbacks in translating neuroprotective therapies into clinical practice. In contrast, the real-world therapy (tPA ...

Reproducible Motor Deficit Following Aortic Occlusion in a Rat Model Of Spinal Cord Ischemia

Spinal cord ischemia is a fatal complication following thoracoabdominal aortic aneurysm surgery. Researchers can investigate the strategies for preventing and treating this complication using experimental models of spinal cord ischemia. The model described here demonstrates varying degrees of paraplegia that relate to the length of occlusion following thoracic aortic occlusion in a rat spinal cord ischemia model.
A 2-Fr. balloon-tipped catheter was advanced through the femoral artery into the descending thoracic aorta until the catheter tip was placed at the left subclavian artery in anesthetized male Sprague-Dawley rats. Spinal cord ischemia was induced by inflating the catheter balloon. After a set period of occlusion (9, 10, or 11 min), the balloon was deflated. Neurologic assessment was performed using the motor deficit index at 24 h after surgery, and the spinal cord was harvested for histopathological examination.
Rats that underwent 9 min of aortic occlusion showed mild and reversible motor impairment in the hind limb. Rats subjected to 10 min of aortic occlusion presented with moderate but reversible motor impairment. Rats subjected to 11 min of aortic occlusion displayed complete and persistent paralysis. The motor neurons in the spinal cord sections were more preserved in rats subjected to shorter duration of aortic occlusion.
Researchers can achieve a reproducible hind limb motor deficit following thoracic aortic occlusion using this spinal cord ischemia model.

This study demonstrates the technique to make a minimally invasive and easily reproducible model of spinal cord ischemia in rats. Various degrees of hind limb motor deficit can be produced by controlling the aortic occlusion time.

Spinal cord ischemia is a fatal complication following thoracoabdominal aortic aneurysm surgery. Researchers can investigate the strategies for preventing ...

Isometric Contractility Measurement of the Mouse Mesenteric Artery Using Wire Myography

The wire myograph technique is used to assess the contractility of vascular smooth muscles in response to depolarization, GPCR agonists/inhibitors and drugs. It is widely used in many studies on the physiological functions of vascular smooth muscle, the pathogenesis of vascular diseases such as hypertension, and the development of smooth muscle relaxant drugs. The mouse is a widely used model animal with a large pool of disease models and genetically modified strains. We introduced this method to measure the isometric contraction of mouse mesenteric artery in detail. A 1.4-mm segment of mouse mesenteric resistance artery was isolated and mounted on a myograph chamber by passing two steel wires through its lumen. After equilibration and normalization steps, the vessel segment was potentiated by a high-K+ solution twice prior to the contraction assay. As an example of the application of this method in drug development, we measured the relaxant effect of a novel natural substance, neoliensinine, isolated from a Chinese herb, embryos of the lotus seed (Nelumbo nucifera Gaertn.) on mouse mesenteric arteries. The vessel segments mounted on the myograph chamber were stimulated with a high-K+ solution. When the force tension reached a stable sustained phase, cumulative doses of neoliensinine were added to the chamber. We found that neoliensinine had a dose-dependent relaxant effect on smooth muscle contraction, thus suggesting that it bears potential activity against hypertension. In addition, as the vessel segment can survive at least 4 hours after mounting and maintain contractility induced by the high-K+ solution for many times, we suggest that the wire myograph system may be used for the time-consuming process of drug screening.

The wire myograph technique is used to investigate vascular smooth muscle functions and screen new drugs. We report a detailed protocol for measuring the isometric contractility of the mouse mesenteric artery and for screening new relaxants of vascular smooth muscle.

The wire myograph technique is used to assess the contractility of vascular smooth muscles in response to depolarization, GPCR agonists/inhibitors and ...

Assessing Therapeutic Angiogenesis in a Murine Model of Hindlimb Ischemia

Critical limb ischemia (CLI) is a serious condition that entails a high risk of lower limb amputation. Despite revascularization being the gold-standard therapy, a considerable number of CLI patients are not suited for either surgical or endovascular revascularization. Angiogenic therapies are emerging as an option for these patients but are currently still under investigation. Before application in humans, those therapies must be tested in animal models and its mechanisms must be clearly understood. An animal model of hindlimb ischemia (HLI) has been developed by the ligation and excision of the distal external iliac and femoral arteries and veins in mice. A comprehensive panel of tests was assembled to assess the effects of ischemia and putative angiogenic therapies at functional, histologic and molecular levels. Laser Doppler was used for the flow measurement and functional assessment of perfusion. Tissue response was evaluated by the analysis of capillary density after staining with the anti-CD31 antibody on histological sections of gastrocnemius muscle and by measurement of collateral vessel density after diaphonization. Expression of angiogenic genes was quantified by RT-PCR targeting selected angiogenic factors exclusively in endothelial cells (ECs) after laser capture microdissection from mice gastrocnemius muscles. These methods were sensitive in identifying differences between ischemic and non-ischemic limbs and between treated and non-treated limbs. This protocol provides a reproducible model of CLI and a framework for testing angiogenic therapies.

Here, a critical hindlimb ischemia experimental model is presented followed by a battery of functional, histologic and molecular tests&#160;to assess the effectiveness of angiogenic therapies.&#8203;

Critical limb ischemia (CLI) is a serious condition that entails a high risk of lower limb amputation. Despite revascularization being the gold-standard ...

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 ...