Name: a mouse model of retinal ischemia-reperfusion injury through elevation of intraocular pressure
Uploaded: 2016-07-14T14:00:00
Description: Watch this Scientific Journal Video about A Mouse Model of Retinal Ischemia-Reperfusion Injury Through Elevation of Intraocular Pressure at JoVE.com

This work was supported by research grants from the National Institutes of Health (EY022383 and EY022683; EJD) and Core grant (P30EY001765), Imaging and Microscopy Core Module.

Ethics Statement: All procedures were performed in accordance with the guidelines set forth by the Johns Hopkins University Institutional Animal Care and Use Committee.
Note: Mice used during filming are C57BL/6 mice from Jackson, although other rodent strains or species may also be used. When using other strains or species, be aware that anesthesia dosages and injury timeline may vary. It is important to adapt I/R conditions to accommodate strain, species, and experimental variations.
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<ol>
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Retinal I/R&#160;injury by elevated IOP has proven its utility in modeling cellular damage and dysfunction, particularly neurodegeneration, in the rodent retinal neurovascular unit. This procedure provides a robust control tissue and is easily accessible in terms of technical sophistication. It has been noted in this and other I/R injury models that increasing the pressure and duration of ischemia may increase injury severity24. For this reason, some practitioners have elected to use ischemic pressures and dur...

Retinal ischemia-reperfusion (I/R) characterizes many human retinal pathologies, including glaucoma, diabetic retinopathy, and retinal vascular occlusions1. In retinal I/R, reduced blood flow (ischemia) in the retinal vasculature creates a state of retinal hypersensitivity to oxygen and other nutrients, precipitating severe oxidative and inflammatory damage when circulation is subsequently reinstated (reperfusion)2. The neural retina appears particularly vulnerable to these changes, with retinal neurodegeneration being perhaps the most salient feature of I/R-induced damage. Presented here is a protocol for modeling retinal I/R injury in the mouse. This technique enables researchers to examine potential mechanisms and treatment strategies for human diseases of the retinal neurovascular unit.
Pioneered in 1952 by surgeons seeking to understand the neurodegenerative consequences of surgical anemia3, rodent retinal I/R by elevated intraocular pressure (IOP) was reestablished in 1991 for the purpose of standardizing neurodegenerative endpoints after ischemic insult4. Using the drip of a saline reservoir to raise IOP above systolic blood pressure, these studies demonstrated that pressurized ocular cannulation was sufficient to suspend the retinal circulation and thereby initiate neuronal degeneration. More recent efforts using retinal I/R by elevated IOP have begun to elaborate the mechanisms underlying I/R-induced retinal neurodegeneration5-12. Multiple groups have reported additional pathologic changes including inflammation13,14, vascular permeability15,16, and capillary degeneration14,17. Taken together, these studies have established retinal I/R injury by elevated IOP as a model of retinal neurovascular disease more generally.
Characterizing the mechanisms of I/R injury is essential for the study of vascular disease. Retinal I/R injury by elevated IOP is one of many hypoxia-induced injury models, including I/R injuries in lung18, heart19, brain20, liver21, kidney22, and intestine23. These models have been paramount in advancing our understanding of vascular illness and its clinical remedies. By extending the investigation of I/R processes to ocular tissues, retinal I/R injury by elevated IOP helps to paint a more comprehensive picture of these related conditions.
Corresponding closely with clinical neurodegenerative conditions in retina, retinal I/R injury by elevated IOP presents a valuable tool for researchers interested in exploring ischemic pathogenesis. The protocol described herein is targeted, tractable, and accessible. It is complemented well by endpoints in neuronal degeneration, such as quantification of retinal neurons, measurement of retinal thickness, and electrophysiological recording of retinal neuron function. This model has proven its utility in advancing neurovascular inquiry, and it shows promise in earning status as a foundational protocol in visual medicine research.

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			<td style="width:136px;">Vet One</td>
			<td style="width:136px;"></td>
			<td style="width:136px;">10 mg/mL</td>
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		<tr height="64">
			<td height="64" style="height:64px;width:136px;">V-Top Surgery Table/Adjustable Hydraulic</td>
			<td style="width:136px;">VSSI</td>
			<td style="width:136px;">100-4041-21</td>
			<td style="width:136px;"></td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:136px;">Tube Fitting Luer Male to Luer Male</td>
			<td style="width:136px;">Warner Instruments</td>
			<td style="width:136px;">64-1579</td>
			<td style="width:136px;"></td>
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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.

The neurodegenerative effects of retinal I/R by elevated IOP are commonly evaluated using two standard approaches. NeuN immunolabeling of neuronal nuclei has revealed significant neuronal cell loss following I/R insult (Figure 1). Briefly, eyes enucleated 7 days after I/R were fixed in paraformaldehyde, labeled with the neuronal cell marker NeuN, and whole-mounted. Images were captured using confocal microscopy, and cells labeled with NeuN were quantified by counting...

Watch this Scientific Journal Video about A Mouse Model of Retinal Ischemia-Reperfusion Injury Through Elevation of Intraocular Pressure at JoVE.com

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

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, ...

The overall goal of this technique, is to provide an experimental model of Retinal Ischemia-Reperfusion Injury, and it's pathologic consequences. This method is commonly used to investigate the mechanisms underlying Retinal Ischemia-Reperfusion, as well as to evaluate potential therapeutic approaches for treating associated pathologies. The main advantage of this technique is that it creates an injury highly targeted to ocular structures, while causing minimal damage to surrounding tissues.The usefulness of this technique extends towards the understanding and three month of multiple manifestations of Retinal Ischemia-Reperfusion Injury, including:inflammation, oxidative stress, and stare dysfunction in the retinal neurovascular unit. Video demonstration of this method is critical because the surgical techniques for cannula placement may be difficult to reproduce without a visual guide. Before beginning the procedure, warm an empty cage on the table.Then insert the sharp end of the primary set pre-pierced Y-site tubing into a bottle of 0.1%Heparin sodium, and hang the bottom of Heparin sodium from an IV pole extension. Snap open the air filter cap on the tubing. Then elevate the Heparin sodium bottle to 163 centimeters from the tabletop to the peak of the sodium Heparin drip, to produce a Heparin sodium flow pressure of 120 mililiters of mercury.Open the primary set pre-pierced Y-site tubing, to allow the Heparin sodium to fill the tubing, and connect the primary set pre-pierced Y-site tubing to the five valve manifold. Then, using Luer male to Luer male tube fittings, connect 30 gauge half-inch needles to the five port manifold. Insert each of the needles into its own ten inch segment of 30 gauge tubing.Then, using hemostats, break new 30 gauge half inch needle tips and insert their blunt ends into open ends of the 30 gauge tubing. Next, use tape to arrange the needle tubes such that the tubes connected to the inner ports are positioned on top of the tubes connected to the outer ports to prevent tangling of the tubing during the Anterior Chamber Cannulation. Now, turn on the 0.1%Heparin sodium flow to the five valve manifold and to each individual port for two to three minutes to remove any air bubbles.Then, turn off all of the ports on the five valve manifold. To perform the cannulation, after administering the anesthesia, place all of the mice into the warm cage on the surgery table, confirming the achievement of deep anesthetization by lack of response to toe pinch after five to ten minutes. Then administer one drop of Tropicamide for pupil dilation, and one drop of Proparacaine for local anesthesia into each of the animals'eyes, and arrange the mice in the order of anesthetization, so that the first mouse anesthetized will be the first mouse to be cannulated.While waiting for the eye drops to take effect, prepare four inch straight pieces of tape, pulling tightly on the tape before tearing, and setting aside one piece of tape per animal. Note that failing to pull tightly on the tape, will result in curling of the tape. When the first mouse is ready, place the animal under a surgical microscope.Then, turn on the first 0.1%Heparin sodium port on the five valve manifold, and use a pair of forceps to gently proptose one eye. Next, insert the 30 gauge cannula needle into the anterior chamber approximately halfway between the zonular fibers and the apex of the cornea. Taking care to avoid penetrating the conrea a second time.Note that a gentle twisting motion is used to insert the cannula deeply into the anterior chamber. Now, press the 30 gauge tubing against the tabletop to minimize any movement of the inserted cannula while reaching for a piece of tape, and use the tape to secure the tubing to the table. Once the tube has been secured, record the start time of the surgery.Use the microscope to verify that there is no leakage, and that the Ischemia-Reperfusion eye is larger than the contralateral eye, to establish the presence of ocular distension. The apply Hypromellose to both eyes every 30 minutes, until the end of the experiment to lubricate the cornea, and to seal any micro leaks. Should an animal stir during the procedure, lift the tail and administer a Ketamine booster intraperitoneally.90 minutes after cannulating the first animal, gently pull the cannula from the anterior chamber, and lubricate both eyes with lubricating jelly. As subsequent cannulae are removed, place each mouse back into the cage on the surgical table, until the animals are fully recovered. After all of the cannulae have been removed, disinfect them with alcohol wipes.Then use a 60 milliliter syringe filled with air to expel the Heparin sodium from the five valve manifold, 30 gauge needles, 30 gauge tubing, and cannulae. Next, rinse all of the instruments with a 60 milliliter syringe filled with distilled water. Finally, expel the distilled water from all of the materials with 60 milliliters of air, and store the disinfected and rinsed equipment for later use.NeuN immunolabeling of neuronal nuclei reveal significant nuronal cell loss, following Ischemia-Reperfusion insult, by confocal microscopic imaging, seven days after Ischemia-Reperfusion Injury. Indeed, manual quantification of the NeuN positive cells in control, and Ischemia-Reperfused eyes, demonstrates a decrease in the gangelion cell layer neuron counts after injury, indicating the presence of Ischemia-Reperfusion induced cell death. Lower a-wave and b-wave amplitudes documented by electroretinography also signify the occurrence of Ischemia-Reperfusion induced impairments in retinal neuronal function compared to control, non-injured eyes.Once mastered, this technique can be performed on ten animals in approximately five hours, including the final two hours spent waiting for the mice to recover from anesthesia. While attempting this procedure, it's important to maintaim deep anesthesia. As an effective sedation will prevent displacement of the cannula by animal movement.Following this procedure, other methods, like electroretinography can be performed to answer additional questions about retinal function. This technique has enabled researchers in the ophthalmology neuroscience and vascular biology fields to explore retinal neurovasuclar pathogenesis, and therapeutic intervention in rodents. After watching this video, you should have a good understanding of how to create a targeted retinal injury, though the cannulation of the ocular anterior chamber.Don't forget, that working with surgical instruments can be extremely hazardous, and that precautions, such as using an effective sharps disposal, should always be taken while performing this procedure.

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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 ...

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 ...

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, ...

Inducing Ischemia-reperfusion Injury in the Mouse Ear Skin for Intravital Multiphoton Imaging of Immune Responses

Ischemia-reperfusion injury (IRI) occurs when there is transient hypoxia due to the obstruction of blood flow (ischemia) followed by a subsequent re-oxygenation of the tissues (reperfusion). In the skin, ischemia-reperfusion (IR) is the main contributing factor to the pathophysiology of pressure ulcers. While the cascade of events leading up to the inflammatory response has been well studied, the spatial and temporal responses of the different subsets of immune cells to an IR injury are not well understood. Existing models of IR using the clamping technique on the skin flank are highly invasive and unsuitable for studying immune responses to injury, while similar non-invasive magnet clamping studies in the skin flank are less-than-ideal for intravital imaging studies. In this protocol, we describe a robust model of non-invasive IR developed on mouse ear skin, where we aim to visualize in real-time the cellular response of immune cells after reperfusion via multiphoton intravital imaging (MP-IVM).

This protocol describes the induction of an ischemia-reperfusion (IR) model on mouse ear skin using magnet clamping. Using a custom-built intravital imaging model, we study in vivo inflammatory responses post-reperfusion. The rationale behind the development of this technique is to extend the understanding of how leukocytes respond to skin IR injury.

Ischemia-reperfusion injury (IRI) occurs when there is transient hypoxia due to the obstruction of blood flow (ischemia) followed by a subsequent ...

Two-vessel Occlusion Mouse Model of Cerebral Ischemia-reperfusion

In this study, a middle cerebral artery (MCA) occlusion mouse model is employed to study cerebral ischemia-reperfusion. A reproducible and reliable mouse model is useful for investigating the pathophysiology of cerebral ischemia-reperfusion and determining potential therapeutic strategies for patients with stroke. Variations in the anatomy of the circle of Willis of C57BL/6 mice affects their infarct volume after cerebral-ischemia-induced injury. Studies have indicated that distal MCA occlusion (MCAO) can overcome this problem and result in a stable infarct size. In this study, we establish a two-vessel occlusion mouse model of cerebral ischemia-reperfusion through the interruption of the blood flow to the right MCA. We distally ligate the right MCA and right common carotid artery (CCA) and restore blood flow after a certain period of ischemia. This ischemia-reperfusion injury induces an infarct of stable size and a behavioral deficit. Peripheral immune cells infiltrate the ischemic brain within the 24 h infiltration period. Additionally, the neuronal loss in the cortical area is less for a longer reperfusion duration. Therefore, this two-vessel occlusion model is suitable for investigating the immune response and neuronal recovery during the reperfusion period after cerebral ischemia.

A mouse model of cerebral ischemia-reperfusion is established to investigate the pathophysiology of stroke. We distally ligate the right middle cerebral artery and right common carotid artery and restore blood flow after 10 or 40 min of ischemia.

In this study, a middle cerebral artery (MCA) occlusion mouse model is employed to study cerebral ischemia-reperfusion. A reproducible and reliable mouse ...

Evaluation of Coronary Flow Reserve After Myocardial Ischemia Reperfusion in Rats

Coronary artery disease is the leading cause of death worldwide. After an acute myocardial infarction, early and successful myocardial intervention via recanalization of the coronary artery is the most effective strategy for reducing the size of ischemic myocardium. The coronary microvasculature cannot be visualized and imaged&#160;in vivo, but there are several invasive and noninvasive techniques that can be used to assess parameters which depend directly on coronary microvascular function. The endothelial function after ischemia reperfusion can be assessed also at the level of the coronary circulation via the coronary flow reserve (CFR).&#160;In this study, peak velocity of left anterior descending (LAD) coronary arteries was measured in rats in vivo via Transthoracic Doppler Echocardiography during resting and stress challenge (induced by Dobutamine). A normal heart can increase its coronary blood flow up to four times above the resting values during stress induction. Following ischemia reperfusion, we found a significantly diminished CFR, which can be used as a marker of coronary microvascular dysfunction. CFR has opened a window on the importance of microvascular dysfunction and has been shown to predict cardiovascular risk independent of whether the severe obstructive disease is present.

Coronary flow reserve (CFR), is defined as the ratio of maximal coronary blood flow to the resting coronary blood flow. We present a protocol for evaluating CFR in rats via ultrasound, which offers the opportunity to predict cardiovascular risk factors in the absence of obstructive coronary disease.

Coronary artery disease is the leading cause of death worldwide. After an acute myocardial infarction, early and successful myocardial intervention via ...

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 ...

Delayed Intramyocardial Delivery of Stem Cells after Ischemia Reperfusion Injury in a Murine Model

There is significant interest in the use of stem cells (SCs) for the recovery of cardiac function in individuals with myocardial injuries. Most commonly, cardiac stem cell therapy is studied by delivering SCs concurrently with the induction of myocardial injury. However, this approach presents two significant limitations: the early hostile pro-inflammatory ischemic environment may affect the survival of transplanted SCs, and it does not represent the subacute infarction scenario where SCs will likely be used. Here we describe a two-part series of surgical procedures for the induction of ischemia-reperfusion injury and delivery of mesenchymal stem cells (MSCs). This method of stem cell administration may allow for the longer viability and retention around damaged tissue by circumventing the initial immune response. A model of ischemia reperfusion injury was induced in mice accompanied by the delivery of mesenchymal stem cells (3.0 x 105), stably expressing the reporter gene firefly luciferase under the constitutively expressed CMV promoter, intramyocardially 7 days later. The animals were imaged via ultrasound and bioluminescent imaging for confirmation of injury and injection of cells, respectively. Importantly, there was no added complication rate when performing this two-procedure approach for SC delivery. This method of stem cell administration, collectively with the utilization of state-of-the-art reporter genes, may allow for the in vivo study of viability and retention of transplanted SCs in a situation of chronic ischemia commonly seen clinically, while also circumventing the initial pro-inflammatory response. In summary, we established a protocol for the delayed delivery of stem cells into the myocardium, which can be used as a potential new approach in promoting regeneration of the damaged tissue.

Stems cells are continuously investigated as potential treatments for individuals with myocardial damage, however, their decreased viability and retention within injured tissue can impact their long-term efficacy. In this manuscript we describe an alternative method for stem cell delivery in a murine model of ischemia reperfusion injury.

There is significant interest in the use of stem cells (SCs) for the recovery of cardiac function in individuals with myocardial injuries. Most commonly, ...