We would like to thank Dr. Lei Chen (Icahn School of Medicine at Mount Sinai, NY) who first established this model in our laboratory. Supported in part by HL126559, DA039576, MH098891, MH63022, MH072567, DA027569, and NSC 2015/17/B/NZ7/02985. Dr. Luc Bertrand is supported in part by a postdoctoral fellowship from the American Heart Association (16POST31170002).

All procedures were approved by the University of Miami Institutional Animal Care and Use Committee (IACUC) in accordance with the National Institutes of Health (NIH) guidelines.&#160;The use to sterile equipment and aseptic techniques is required.
1. Preparing the Occlusion Suture
<ol>
	<li>Use a suture of 0.21 mm diameter for mice between 20 - 25 g and 0.23 mm for mice between 25 - 35 g of body weight. The choice of the type of sutures for the MCAO procedure depends on animal weight.</li>
	<li>Using a silver pen, mark the suture at 9 mm starting from the silicone coated tip. This will serve as a guide for insertion length.</li>
</ol>
2. Preparation for Surgery
<ol>
	<li>Anesthetize mouse with isoflurane mixed with oxygen, using a laboratory anesthesia system. Use isoflurane at setting 5 and oxygen flow at 2 on the commercial machine (See Materials Table). Transfer the animal to the surgery surface and sustain anesthesia using a nose cone (use isoflurane setting 1.5 - 2.5 and oxygen flow at 2).
	<ol>
		<li>Ensure that the mouse respiratory rate is around 1 - 2 respiration per sec without gasping. In addition, ensure that the animal does not exhibit whiskers stimulation reaction and pedal reflex (toe pinch). Monitor respiration rate and effort during the surgery, at least every 5 min.</li>
	</ol>
	</li>
	<li>Put a drop of ophthalmic lubricant on each eye using a sterile swab to prevent them from drying during the procedure. Alternatively, apply ophthalmic ointment to the eye from a sterile pharmaceutical tube.</li>
	<li>Flip the animal on its back and shave the incision area. Afterward, thoroughly disinfect the surgery area using 70% ethanol, followed by Chlorhexidine, and the final swab with 70% ethanol.&#160;Place the animal on a warm surgical surface under a stereomicroscope.</li>
</ol>
3. Dissection of the Common Carotid Artery and Internal/External Branching
<ol>
	<li>Using surgical scissors and forceps, perform a shallow midline incision in the neck, from above the breast bone to below the jaw (approximately 3 - 4 cm).&#160;&#160;Surgical drape should be placed around the surgery area to prevent instruments from coming in contact with non-sterile surfaces. The surgical drape was omitted in the current video to aid filming.</li>
	<li>Using forceps, carefully separate fatty and connective tissue to expose the trachea. Tissue should easily and naturally separate to both sides.</li>
	<li>Place a pillow (round object, about 0.5 cm in diameter) on the back of the neck of the mice to extend the neck, further exposing the area for surgery.</li>
	<li>Open the incision using either a tissue retractor or hooks.</li>
	<li>On the animal&#39;s left side of the trachea, carefully tweeze apart the connective tissue to expose the left common carotid artery (CCA). Be careful not to damage nerves and major veins bundled with the CCA.</li>
	<li>Continue exposing the CCA, being careful to detach from underlying tissue, and expose the top &#34;Y&#34; branching of the internal cerebral artery (ICA) and external cerebral artery (ECA). To aid in detaching the CCA, insert the curved forceps under the CCA to pierce the connective tissue and then slowly allow them to open.</li>
</ol>
4. Preparation of the CCA for the MCAO Suture Insertion
<ol>
	<li>Insert 3 segments of nylon suture of about 4 cm in length under the CCA. Ensure that the CCA is not twisted as this would drastically complicate the insertion of the suture.</li>
	<li>At the lowest point possible, close the bottom suture using a permanent knot.</li>
	<li>Tie the top suture just below the ICA/ECA branching using a removable slip knot.</li>
	<li>Tie the middle suture using a removable slip knot, but keep it wide open. It is important to leave plenty of space as not to hinder suture insertion.</li>
	<li>Using microdissection spring scissors, perform an incision in the CCA between the bottom and middle sutures. Perform the 0.2 mm incision close to the bottom suture.</li>
</ol>
5. Middle Cerebral Artery Occlusion
<ol>
	<li>Using forceps, insert the MCAO suture into the CCA incision, guiding it up to the top. Perform this step quickly after step 4.5 to prevent clotting and closing of the CCA opening. In the event that suture insertion is blocked, use the tips of forceps to reopen the incision.</li>
	<li>Gently tie down the middle suture on the MCAO suture silicone part using a slip knot to restrict blood flow around it, but loose enough to allow it to move freely.</li>
	<li>Carefully undo the top suture, making sure that the MCAO suture does not slip out.</li>
	<li>Insert the MCAO suture in the ICA by a couple of millimeters and then reclose the top suture, in the same manner as described in step 5.2.</li>
	<li>Guide the MCAO suture to the occlusion area. Indication of successful insertion is evident by the low amount of blood backflow from the CCA incision and that the silver 9 mm mark is situated between the CCA incision and the ICA/ECA bifurcation. Further confirmation of successful occlusion can be obtained using monitoring methods such as a laser Doppler blood flow monitoring system15,16. 
	NOTE: A drop in 90% of blood flow to the middle brain area on the occluded area side indicates successful occlusion.</li>
	<li>After successful occlusion, tie down the middle and top suture tightly. If performing sham insertion, do not reclose sutures but instead immediately skip to step 7.3.</li>
</ol>
6. Incision Closing and Post-operative Care
<ol>
	<li>Tuck in the sutures into the incision area.</li>
	<li>Remove retractor or tissue hooks and pillow.</li>
	<li>Clean suture area using sterile saline and a cotton swab.</li>
	<li>Close the incision using nylon suture/needle and forceps.</li>
	<li>Administer anti-inflammatory (e.g., Carprofen 10 mg/kg, s.c.) and analgesic (e.g., Buprenorphine 0.1 mg/kg s.c., twice a day) drugs to alleviate post-operative discomfort. Place the mice in a cage placed on a heated pad to prevent hypothermia and give ad labium access to water and softened food.</li>
	<li>Monitor the recovery of animals (5 - 10 min) and for signs of stroke. They can vary from mild lateral paralysis and circling to severe contraction of the contralateral flank and rolling. Several evaluation points are listed in the discussion.&#160;Animals displaying signs of respiratory distress or severe seizures should be euthanized.</li>
	<li>Depending on ischemia reperfusion protocol, leave the MCAO suture in place from 30 min to 120 min or more.&#160;Reducing occlusion time prevents mortality.</li>
	<li>For permanent occlusion, leave the MCAO suture in place for 24 hr, however significant mortality rate is to be expected. After this time lapse, proceed to step 7.
	<ol>
		<li>If using permanent occlusion model, keep mice in cage until end point. At that time, remove suture (steps 7.1 to 7.8). This procedure can also be performed after euthanasia.</li>
	</ol>
	</li>
</ol>
7. Reperfusion
<ol>
	<li>Anesthetize the animal again (follow instructions in 2.1) and remove wound closing sutures.</li>
	<li>Using forceps and tissue separators, re-open the incision and expose the CCA.</li>
	<li>Carefully remove the top suture and gently pull on the MCAO suture until the silicone coated part is situated at the middle knot.</li>
	<li>Redo the top knot on the suture to prevent blood from flowing pass the suture (it does not have to be a slip knot).</li>
	<li>Carefully undo the middle knot and pull the suture past the top knot, but keep it inside the CCA.</li>
	<li>Tightly close the top knot to block artery blood flow.</li>
	<li>Pull out completely the MCAO suture and close tightly the middle knot.</li>
	<li>The MCAO suture can be re-used several times. After each use, clean the suture carefully in 70% ethanol to remove contaminants (e.g., blood or tissue) using a sterile gauze. Afterwards, place the suture in a sterilizer pouch and sterilize it.</li>
	<li>Repeat steps 6.1 - 6.4 and monitor animal recovery.</li>
</ol>
8. Tissue Analysis
<ol>
	<li>To monitor stroke volume, dissect out the brain.
	<ol>
		<li>Euthanize the mouse using a two-step process. First, expose the animal to an overdose of isoflurane until breathing stops.&#160;For TTC staining, decapitate the mouse immediately and proceed to brain extraction. For brain sectioning (e.g., for immunostaining analyses), perform perfusion via a cardiac puncture prior to decapitation. &#160;</li>
		<li>Cut-off the head at the base of the skull and cut the scalp from the neck opening to the top of the skull up to between the eyes. With the skull exposed, cut the bone along both sides starting from the skull base opening up to the eye socket. Make this cut along the wide part of the skull. Be careful not to reach too deep with scissors to prevent damaging the brain.</li>
		<li>Afterwards, cut the bone between the two eye sockets.</li>
	</ol>
	</li>
	<li>Using forceps, lift up the top of the skull to expose the brain. There should be only a small resistance. If it does not lift easily, skull incisions may be incomplete. Pry out the brain gently using blunt curved forceps. The brain might still be attached by several nerves. Proceed slowly, removing attachments along the way.</li>
	<li>Place the fresh brain in a 1 mm brain matrix, add a couple of drops of PBS, and slice along the matrix using a razor blade or cryostat blade.</li>
	<li>Transfer the brain to a 100 mm dish and add staining solution (2% 2,3,5-triphenyltetrazolium chloride [TTC] dissolved in PBS) to cover the bottom of the dish. Using two forceps, separate all brain slices (front facing down) and place them in order at the bottom of the dish. 
	NOTE: Staining will turn viable tissue red, with non-viable tissue remaining white. Warming the solution to 37 &#176;C will accelerate staining. Signs of stroke area (white) can be seen as quickly as 90 min post stroke and remain visible for more than 7 days. Imaging should be done along with a ruler to allow calculation of stroke volume.</li>
	<li>Process dissected brains for sectioning, immuno-staining, protein isolation, or a variety of other procedures17,18,19.</li>
</ol>

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	<li>Cuomo, O., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Antithrombin+reduces+ischemic+volume,+ameliorates+neurologic+deficits,+and+prolongs+animal+survival+in+both+transient+and+permanent+focal+ischemia.">Antithrombin reduces ischemic volume, ameliorates neurologic deficits, and prolongs animal survival in both transient and permanent focal ischemia.</a> Stroke. 38 (12), 3272-3279 (2007).</li><li>Wauquier, A., Melis, W., Janssen, P. 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Authors have no competing or conflicts of interest.

The successful utilization of the described MCAO method is highly dependent on an understanding of cerebral blood flow anatomy. Since the correct placement of the suture is hard to discern due to the lack of direct visual clues, repeated practice is important to master the procedure before using it for investigative studies. Stroke volume should be analyzed to ensure consistent results. The addition of a laser Doppler system can help to determine the successful occlusion of blood flow and should be used periodically to e...

The study of cardiovascular disease, such as stroke, relies on the use of in vivo models. To understand the possible implication of ischemia, drug toxicity, and/or treatment, there is a need to use a suitable, standardized, reliable, and reproducible model of the disease, which enables comparative studies between treatment groups. In this manuscript, we are using mice, given the availability of a large number of transgenic mice and standardized assessment models. Raking scores to assess motor and behavior deficits following experimental ischemic stroke and the following recovery have been developed1,2.
Several ischemic stroke models are available, such as complete global cerebral ischemia, incomplete global ischemia, multifocal cerebral ischemia and focal cerebral ischemia. The latter group is also the category of stroke most prevalent in patients. The majority of events are initiated by the formation of an embolic or thrombotic occlusion at or near the middle cerebral artery (MCA). Given these parameters, the model presented closely mimics disease etiology of human stroke and makes results obtained highly relevant3. Nevertheless, the translation of discoveries from animal models to disease treatment in humans has proven to be challenging. Up to now, only the use of thrombolytic tissue plasminogen activator has been approved for treatment of acute ischemic stroke4.
Among models of focal cerebral ischemia in mouse, posterior cerebral circulation stroke model and cerebral venous thrombosis model are highly invasive, diminishing their applicability and restricting the range of analyses that can be performed. However, other techniques, such as the embolic model, photothrombosis model, endothelin-1 induced stroke model, and intraluminal suture middle cerebral artery occlusion (MCAO) model, are available for use without such limitations. The MCAO model is a technique described in this protocol. It offers a reliable method of inducing focal cerebral ischemia that can be readily reperfused and performed in a high-throughput manner. There are two approaches to this model, namely, the Zea-Longa and Koizumi methods. They differ slightly in the way the occlusion suture is inserted in the vasculature. In the Zea-Longa technique, the suture is inserted via the external carotid artery5. The technique presented here is modified from the Koizumi method in which the occluding suture is inserted via the common carotid artery6.
The MCAO model has been successfully applied to evaluate different events occurring during ischemic stroke. Following reperfusion, brain edema can be observed along with the breakdown of the blood-brain barrier. Peak neuronal death is usually observed at 24 hr; however, it returns to baseline levels after 7 days7. In humans, sex and age are important variables when determining stroke outcome, this is also observed in mice and rats8,9,10. Several publications have used the MCAO model to demonstrate treatment efficiency11,12,13,14.

<table border="0" cellpadding="0" cellspacing="0" width="544">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:276px;">MCAO suture 0.23mm</td>
			<td style="width:149px;">Doccol</td>
			<td style="width:119px;">702345PK5Re</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:276px;">MCAO suture 0.21mm</td>
			<td style="width:149px;">Doccol</td>
			<td style="width:119px;">702145PK5Re</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:276px;">Silver pen</td>
			<td style="width:149px;">staples</td>
			<td style="width:119px;">503205</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:276px;">Anesthesia machine</td>
			<td style="width:149px;">Vetequip</td>
			<td style="width:119px;">901806</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:276px;">Surgical scissors</td>
			<td style="width:149px;">Fine science tool</td>
			<td style="width:119px;">14558-09</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:276px;">Surgical forceps straight tip</td>
			<td style="width:149px;">Fine science tool</td>
			<td style="width:119px;">00108-11</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:276px;">Surgical forceps angled tip</td>
			<td style="width:149px;">Fine science tool</td>
			<td style="width:119px;">00109-11</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:276px;">Spring scissors</td>
			<td style="width:149px;">Fine science tool</td>
			<td style="width:119px;">15000-08</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:276px;">Nylon suture</td>
			<td style="width:149px;">Braintree scintific</td>
			<td style="width:119px;">SUT-S 104</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:276px;">Closing suture</td>
			<td style="width:149px;">VWR</td>
			<td style="width:119px;">95057-036</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:276px;">Isoflurane</td>
			<td style="width:149px;">Piramal</td>
			<td style="width:119px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:276px;">2,3,5-Triphenyltetrazolium chloride</td>
			<td style="width:149px;">FisherSci</td>
			<td style="width:119px;">50-121-8005</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:276px;">Brain block</td>
			<td style="width:149px;">Braintree scintific</td>
			<td style="width:119px;">BS-A 5000C</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:276px;">Cryostat blade</td>
			<td style="width:149px;">VWR</td>
			<td style="width:119px;">89202-606</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:276px;">Optional:</td>
			<td style="width:149px;"></td>
			<td style="width:119px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:276px;">Periflux Laser doppler system</td>
			<td style="width:149px;">Perimed</td>
			<td style="width:119px;">Periflux 5000</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:276px;">Monitoring unit</td>
			<td style="width:149px;">Perimed</td>
			<td style="width:119px;">PF 5010 - LDPM</td>
		</tr>
	</tbody>
</table>

induction of ischemic stroke and ischemia-reperfusion in mice using the middle artery occlusion technique and visualization of infarct area

Cerebrovascular disease is highly prevalent in the global population and encompasses several types of conditions, including stroke. To study the impact of stroke on tissue injury and to evaluate the effectiveness of therapeutic interventions, several experimental models in a variety of species were developed. They include complete global cerebral ischemia, incomplete global ischemia, focal cerebral ischemia, and multifocal cerebral ischemia. The model described in this protocol is based on the middle cerebral artery occlusion (MCAO) and is related to the focal ischemia category. This technique produces consistent focal ischemia in a strictly defined region of the hemisphere and is less invasive than other methods. The procedure described is performed on mice, given the availability of several genetic variants and the high number of tests standardized for mice to aid in the behavioral and neurodeficit evaluation.

The insertion route for the occlusion suture is demonstrated in Figure 1. The MCAO suture is to be routed to the occlusion area, bifurcating in the ICA. Successful occlusion of the MCA will lead to tissue injury, visible by TTC staining. Figure 2 presents images of staining from sham treated animal (Figure 2A) and from a 60 min MCAO ischemia reperfusion animal (staining at 90 min or 24 hr post-occlusion, Figure 2B). To de...

Watch this Scientific Journal Video about Induction of Ischemic Stroke and Ischemia-reperfusion in Mice Using the Middle Artery Occlusion Technique and Visualization of Infarct Area at JoVE.com

Induction of Ischemic Stroke and Ischemia-reperfusion in Mice Using the Middle Artery Occlusion Technique and Visualization of Infarct Area

We describe a mouse model of stroke induced by the occlusion of the middle cerebral artery using a silicone coated suture. The protocol can be applied to induce permanent occlusion or a temporary ischemia, followed by reperfusion.

Cerebrovascular disease is highly prevalent in the global population and encompasses several types of conditions, including stroke. To study the impact of ...

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16.1K Views.  University of Miami. We describe a mouse model of stroke induced by the occlusion of the middle cerebral artery using a silicone coated suture. The protocol can be applied to induce permanent occlusion or a temporary ischemia, followed by reperfusion.

Video: Induction of Ischemic Stroke and Ischemia-reperfusion in Mice Using the Middle Artery Occlusion Technique and Visualization of Infarct Area

Modeling Stroke in Mice - Middle Cerebral Artery Occlusion with the Filament Model

Stroke is among the most frequent causes of death and adult disability, especially in highly developed countries. However, treatment options to date are very limited. To meet the need for novel therapeutic approaches, experimental stroke research frequently employs rodent models of focal cerebral ischaemia. Most researchers use permanent or transient occlusion of the middle cerebral artery (MCA) in mice or rats.
Proximal occlusion of the middle cerebral artery (MCA) via the intraluminal suture technique (so called filament or suture model) is probably the most frequently used model in experimental stroke research. The intraluminal MCAO model offers the advantage of inducing reproducible transient or permanent ischaemia of the MCA territory in a relatively non-invasive manner. Intraluminal approaches interrupt the blood flow of the entire territory of this artery. Filament occlusion thus arrests flow proximal to the lenticulo-striate arteries, which supply the basal ganglia. Filament occlusion of the MCA results in reproducible lesions in the cortex and striatum and can be either permanent or transient. In contrast, models inducing distal (to the branching of the lenticulo-striate arteries) MCA occlusion typically spare the striatum and primarily involve the neocortex. In addition these models do require craniectomy. In the model demonstrated in this article, a silicon coated filament is introduced into the common carotid artery and advanced along the internal carotid artery into the Circle of Willis, where it blocks the origin of the middle cerebral artery. In patients, occlusions of the middle cerebral artery are among the most common causes of ischaemic stroke. Since varying ischemic intervals can be chosen freely in this model depending on the time point of reperfusion, ischaemic lesions with varying degrees of severity can be produced. Reperfusion by removal of the occluding filament at least partially models the restoration of blood flow after spontaneous or therapeutic (tPA) lysis of a thromboembolic clot in humans.
In this video we will present the basic technique as well as the major pitfalls and confounders which may limit the predictive value of this model.

Filamentous occlusion of the Middle cerebral artery is a common model for studying ischemic stroke in mice.

Stroke is among the most frequent causes of death and adult disability, especially in highly developed countries. However, treatment options to date are ...

Mouse Model of Middle Cerebral Artery Occlusion

Stroke is the most common fatal neurological disease in the United States 1. The majority of strokes (88%) result from blockage of blood vessels in the brain (ischemic stroke) 2. Since most ischemic strokes (~80%) occur in the territory of middle cerebral artery (MCA) 3, many animal stroke models that have been developed have focused on this artery. The intraluminal monofilament model of middle cerebral artery occlusion (MCAO) involves the insertion of a surgical filament into the external carotid artery and threading it forward into the internal carotid artery (ICA) until the tip occludes the origin of the MCA, resulting in a cessation of blood flow and subsequent brain infarction in the MCA territory 4. The technique can be used to model permanent or transient occlusion 5. If the suture is removed after a certain interval (30 min, 1 h, or 2 h), reperfusion is achieved (transient MCAO); if the filament is left in place (24 h) the procedure is suitable as a model of permanent MCAO. This technique does not require craniectomy, a neurosurgical procedure to remove a portion of skull, which may affect intracranial pressure and temperature 6. It has become the most frequently used method to mimic permanent and transient focal cerebral ischemia in rats and mice 7,8. To evaluate the extent of cerebral infarction, we stain brain slices with 2,3,5-triphenyltetrazolium chloride (TTC) to identify ischemic brain tissue 9. In this video, we demonstrate the MCAO method and the determination of infarct size by TTC staining.

We demonstrate in the video a method for producing a middle cerebral artery occlusion in adult mice using an intraluminal monofilament. We also show how to evaluate the extent of cerebral infarction by 2,3,5-triphenyltetrazolium chloride (TTC) staining.

Stroke is the most common fatal neurological disease in the United States 1. The majority of strokes (88%) result from blockage of blood vessels in the ...

Intraluminal Middle Cerebral Artery Occlusion (MCAO) Model for Ischemic Stroke with Laser Doppler Flowmetry Guidance in Mice

Stroke is the third leading cause of death and the leading cause of disability in the world, with an estimated cost of near $70 billion 
in the United States in 20091,2. The intraluminal middle cerebral artery occlusion (MCAO) model was developed by Koizumi4 in 1986 to simulate this 
impactful human pathology in the rat. A modification of the MCAO method was later presented by Longa3. Both techniques have been widely used to identify 
molecular mechanisms of brain injury resulting from ischemic stroke and potential therapeutic modalities5. This relatively noninvasive method in rats has been 
extended to use in mice to take advantage of transgenic and knockout strains6,7. To model focal cerebral ischemia, an intraluminal suture is advanced via 
the internal carotid artery to occlude the base of the MCA. Retracting the suture after a specified period of time mimics spontaneous reperfusion, but the 
suture can also be permanently retained. This video will be demonstrating the two major approaches for performing intraluminal MCAO procedure in mice in a 
stepwise fashion, as well as providing insights for potential drawbacks and pitfalls. The ischemic brain tissue will subsequently be stained by 
2,3,5-triphenyltetrazolium chloride (TTC) to evaluate the extent of cerebral infarction8.

Intraluminal Middle Cerebral Artery Occlusion MCAO Model for Ischemic Stroke with Laser Doppler Flowmetry Guidance in Mice

The intraluminal middle cerebral artery occlusion (MCAO) model is the most frequent used model among experimental ischemic stroke models. Here we will demonstrate the entire model in detail with the guide of Laser Doppler flowmetry, and its representative results.

Stroke is the third leading cause of death and the leading cause of disability in the world, with an estimated cost of near $70 billion 
in the United ...

Bilateral Common Carotid Artery Occlusion as an Adequate Preconditioning Stimulus to Induce Early Ischemic Tolerance to Focal Cerebral Ischemia

There is accumulating evidence, that ischemic preconditioning - a non-damaging ischemic challenge to the brain - confers a transient protection to a subsequent damaging ischemic insult. We have established bilateral common carotid artery occlusion as a preconditioning stimulus to induce early ischemic tolerance to transient focal cerebral ischemia in C57Bl6/J mice. In this video, we will demonstrate the methodology used for this study.

There is accumulating evidence, that ischemic preconditioning (PC) &#x2013; a non-damaging ischemic challenge to the brain - confers a transient protection to a subsequent damaging ischemic insult. We established bilateral common carotid artery occlusion (BCCAO) as a preconditioning stimulus to induce early ischemic tolerance (IT) to transient focal cerebral ischemia (induced by middle cerebral artery occlusion, MCAO) in C57Bl6/J mice.

There is accumulating evidence, that ischemic preconditioning - a non-damaging ischemic challenge to the brain - confers a transient protection to a ...

Endothelin-1 Induced Middle Cerebral Artery Occlusion Model for Ischemic Stroke with Laser Doppler Flowmetry Guidance in Rat

Stroke is the number one cause of disability and third leading cause of death in the world, costing an estimated $70 billion in the United States in 20091, 2. Several models of cerebral ischemia have been developed to mimic the human condition of stroke. It has been suggested that up to 80% of all strokes result from ischemic damage in the middle cerebral artery (MCA) area3. In the early 1990s, endothelin-1 (ET-1) 4 was used to induce ischemia by applying it directly adjacent to the surface of the MCA after craniotomy. Later, this model was modified 5 by using a stereotaxic injection of ET-1 adjacent to the MCA to produce focal cerebral ischemia. The main advantages of this model include the ability to perform the procedure quickly, the ability to control artery constriction by altering the dose of ET-1 delivered, no need to manipulate the extracranial vessels supplying blood to the brain as well as gradual reperfusion rates that more closely mimics the reperfusion in humans5-7. On the other hand, the ET-1 model has disadvantages that include the need for a craniotomy, as well as higher variability in stroke volume8. This variability can be reduced with the use of laser Doppler flowmetry (LDF) to verify cerebral ischemia during ET-1 infusion. Factors that affect stroke variability include precision of infusion and the batch of the ET-1 used6. Another important consideration is that although reperfusion is a common occurrence in human stroke, the duration of occlusion for ET-1 induced MCAO may not closely mimic that of human stroke where many patients have partial reperfusion over a period of hours to days following occlusion9, 10. This protocol will describe in detail the ET-1 induced MCAO model for ischemic stroke in rats. It will also draw attention to special considerations and potential drawbacks throughout the procedure.

Several animal models of cerebral ischemia have been developed to simulate the human condition of stroke. This protocol describes the endothelin-1 (ET-1) induced middle cerebral artery occlusion (MCAO) model for ischemic stroke in rats. In addition, important considerations, advantages, and shortcomings of this model are discussed.

Stroke is the number one cause of disability and third leading cause of death in the world, costing an estimated $70 billion in the United States in ...

Utilizing a Cranial Window to Visualize the Middle Cerebral Artery During Endothelin-1 Induced Middle Cerebral Artery Occlusion

Creation of a cranial window is a method that allows direct visualization of structures on the cortical surface of the brain1-3. This technique can be performed in many locations overlying the rat cerebrum, but is most easily carried out by creating a craniectomy over the readily accessible frontal or parietal bones. Most frequently, we have used this technique in combination with the endothelin-1 middle cerebral artery occlusion model of ischemic stroke to quantify the changes in middle cerebral artery vessel diameter that occur with injection of endothelin-1 into the brain parenchyma adjacent to the proximal MCA4, 5. In order to visualize the proximal portion of the MCA during endothelin -1 induced MCAO, we use a technique to create a cranial window through the temporal bone on the lateral aspect of the rat skull (Figure 1). Cerebral arteries can be visualized either with the dura intact or with the dura incised and retracted. Most commonly, we leave the dura intact during visualization since endothelin-1 induced MCAO involves delivery of the vasoconstricting peptide into the brain parenchyma. This bypasses the need to incise the dura directly over the visualized vessels for drug delivery. This protocol will describe how to create a cranial window to visualize cerebral arteries in a step-wise fashion, as well as how to avoid many of the potential pitfalls pertaining to this method.

This article describes a method for visualizing rat cerebral arteries through a cranial window using temporal craniectomy in order to view proximal portions of the middle cerebral artery (Figure 1). This versatile method can be combined with various techniques of drug delivery to measure cerebral artery reactivity in vivo.

Creation of a cranial window is a method that allows direct visualization of structures on the cortical surface of the brain1-3. This technique can be ...

Optimized System for Cerebral Perfusion Monitoring in the Rat Stroke Model of Intraluminal Middle Cerebral Artery Occlusion

The translational potential of pre-clinical stroke research depends on the accuracy of experimental modeling. Cerebral perfusion monitoring in animal models of acute ischemic stroke allows to confirm successful arterial occlusion and exclude subarachnoid hemorrhage. Cerebral perfusion monitoring can also be used to study intracranial collateral circulation, which is emerging as a powerful determinant of stroke outcome and a possible therapeutic target. Despite a recognized role of Laser Doppler perfusion monitoring as part of the current guidelines for experimental cerebral ischemia, a number of technical difficulties exist that limit its widespread use. One of the major issues is obtaining a secure and prolonged attachment of a deep-penetration Laser Doppler probe to the animal skull. In this video, we show our optimized system for cerebral perfusion monitoring during transient middle cerebral artery occlusion by intraluminal filament in the rat. We developed in-house a simple method to obtain a custom made holder for twin-fibre (deep-penetration) Laser Doppler probes, which allow multi-site monitoring if needed. A continuous and prolonged monitoring of cerebral perfusion could easily be obtained over the intact skull.

Cerebral perfusion monitoring has been demonstrated to improve accuracy in ischemic stroke models. Technical difficulties often limit the use of this essential tool for cerebrovascular research. In this video, an optimized system is shown to obtain a single or multi-site hemodynamic monitoring during intraluminal middle cerebral artery occlusion in rats.

The translational potential of pre-clinical stroke research depends on the accuracy of experimental modeling. Cerebral perfusion monitoring in animal ...

Modeling Stroke in Mice: Permanent Coagulation of the Distal Middle Cerebral Artery

Stroke is the third most common cause of death and a main cause of acquired adult disability in developed countries. Only very limited therapeutical options are available for a small proportion of stroke patients in the acute phase. Current research is intensively searching for novel therapeutic strategies and is increasingly focusing on the sub-acute and chronic phase after stroke because more patients might be eligible for therapeutic interventions in a prolonged time window. These delayed mechanisms include important pathophysiological pathways such as post-stroke inflammation, angiogenesis, neuronal plasticity and regeneration. In order to analyze these mechanisms and to subsequently evaluate novel drug targets, experimental stroke models with clinical relevance, low mortality and high reproducibility are sought after. Moreover, mice are the smallest mammals in which a focal stroke lesion can be induced and for which a broad spectrum of transgenic models are available. Therefore, we describe here the mouse model of transcranial, permanent coagulation of the middle cerebral artery via electrocoagulation distal of the lenticulostriatal arteries, the so-called &#8220;coagulation model&#8221;. The resulting infarct in this model is located mainly in the cortex; the relative infarct volume in relation to brain size corresponds to the majority of human strokes. Moreover, the model fulfills the above-mentioned criteria of reproducibility and low mortality. In this video we demonstrate the surgical methods of stroke induction in the &#8220;coagulation model&#8221; and report histological and functional analysis tools.

Various murine models of middle cerebral artery occlusion (MCAO) are widely used in experimental brain research. Here, we demonstrate the model of transcranial permanent distal MCAO which produces consistent cortical infarction of a size corresponding to damage imposed by the majority of human ischemic strokes.

Stroke is the third most common cause of death and a main cause of acquired adult disability in developed countries. Only very limited therapeutical ...

Embolic Middle Cerebral Artery Occlusion (MCAO) for Ischemic Stroke with Homologous Blood Clots in Rats

Clinically, thrombolytic therapy with use of recombinant tissue plasminogen activator (tPA) remains the most effective treatment for acute ischemic stroke. However, the use of tPA is limited by its narrow therapeutic window and by increased risk of hemorrhagic transformation. There is an urgent need to develop suitable stroke models to study new thrombolytic agents and strategies for treatment of ischemic stroke. At present, two major types of ischemic stroke models have been developed in rats and mice: intraluminal suture MCAO and embolic MCAO. Although MCAO models via the intraluminal suture technique have been widely used in mechanism-driven stroke research, these suture models do not mimic the clinical situation and are not suitable for thrombolytic studies. Among these models, the embolic MCAO model closely mimics human ischemic stroke and is suitable for preclinical investigation of thrombolytic therapy. This embolic model was first developed in rats by Overgaard et al.1 in 1992 and further characterized by Zhang et al. in 19972. Although embolic MCAO has gained increasing attention, there are technical problems faced by many laboratories. To meet increasing needs for thrombolytic research, we present a highly reproducible model of embolic MCAO in the rat, which can develop a predictable infarct volume within the MCA territory. In brief, a modified PE-50 tube is gently advanced from the external carotid artery (ECA) into the lumen of the internal carotid artery (ICA) until the tip of the catheter reaches the origin of the MCA. Through the catheter, a single homologous blood clot is placed at the origin of the MCA. To identify the success of MCA occlusion, regional cerebral blood flow was monitored, neurological deficits and infarct volumes were measured. The techniques presented in this paper should help investigators to overcome technical problems for establishing this model for stroke research.

Embolic Middle Cerebral Artery Occlusion MCAO for Ischemic Stroke with Homologous Blood Clots in Rats

In this paper, we demonstrate a standard method for producing an embolic middle cerebral artery occlusion with homologous blood clots (fibrin-rich) in adult rat. This model closely mimics human ischemic stroke and is suitable for preclinical study of thrombolytic therapy for ischemic stroke.

Clinically, thrombolytic therapy with use of recombinant tissue plasminogen activator (tPA) remains the most effective treatment for acute ischemic ...

Quantification of Neurovascular Protection Following Repetitive Hypoxic Preconditioning and Transient Middle Cerebral Artery Occlusion in Mice

Experimental animal models of stroke are invaluable tools for understanding stroke pathology and developing more effective treatment strategies. A 2 week protocol for repetitive hypoxic preconditioning (RHP) induces long-term protection against central nervous system (CNS) injury in a mouse model of focal ischemic stroke. RHP consists of 9 stochastic exposures to hypoxia that vary in both duration (2 or 4 hr) and intensity (8% and 11% O2). RHP reduces infarct volumes, blood-brain barrier (BBB) disruption, and the post-stroke inflammatory response for weeks following the last exposure to hypoxia, suggesting a long-term induction of an endogenous CNS-protective phenotype. The methodology for the dual quantification of infarct volume and BBB disruption is effective in assessing neurovascular protection in mice with RHP or other putative neuroprotectants. Adult male Swiss Webster mice were preconditioned by RHP or duration-equivalent exposures to 21% O2 (i.e. room air). A 60 min transient middle cerebral artery occlusion (tMCAo) was induced 2 weeks following the last hypoxic exposure. Both the occlusion and reperfusion were confirmed by transcranial laser Doppler flowmetry. Twenty-two hr after reperfusion, Evans Blue (EB) was intravenously administered through a tail vein injection. 2 hr later, animals were sacrificed by isoflurane overdose and brain sections were stained with 2,3,5- triphenyltetrazolium chloride (TTC). Infarcts volumes were then quantified. Next, EB was extracted from the tissue over 48 hr to determine BBB disruption after tMCAo. In summary, RHP is a simple protocol that can be replicated, with minimal cost, to induce long-term endogenous neurovascular protection from stroke injury in mice, with the translational potential for other CNS-based and systemic pro-inflammatory disease states.

This protocol describes repetitive hypoxic preconditioning, or brief exposures to systemic hypoxia that reduce infarct volumes and blood-brain barrier disruption following transient middle cerebral artery occlusion in mice. It also details dual quantification of infarct volume and blood-brain barrier disruption after stroke to assess the efficacy of neurovascular protection.

Experimental animal models of stroke are invaluable tools for understanding stroke pathology and developing more effective treatment strategies. A 2 week ...