This work was funded by the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement n&deg; 201024 and n&deg; 202213 (European Stroke Network). Additional funding was given by the Bundesministerium f&uuml;r Bildung und Forschung (Center for Stroke Research Berlin), and the Deutsche Forschungsgemeinschaft (Exzellenzcluster NEUROCURE).
The authors would like to thank Mareike Thielke (Dep. for Experimental Neurology, Charit&eacute; Berlin) for the support during the operation and Elke Ludwig (Charit&eacute; Video Services) for producing the animation.

To guarantee high quality and reproducibility, we recommend the use of Standard Operating Procedures (SOP). In this video, published SOPs as developed and used in our laboratory are applied. 1
1. Middle Cerebral Artery Occlusion
 <ol>
 <li>Mice are anaesthetized with an appropriate anaesthetic regime in consult with veterinary staff. (E.g. induction with 1.5 - 2 % Isoflurane and maintainance with 1.0 - 1.5 % Isoflurane in 2/3 N2O and 1/3 O2 using a vaporizer).
 <ol>
 <li>Body temperature of the mice is maintained at 36.5&deg;C &plusmn; 0.5&deg;C during surgery with a heating plate. A feedback controlled heating pad, which warms according to the rectal temperature of the mouse, is highly recommended.</li>
 <li>Disinfect the skin and surrounding fur with an appropriate agent (e.g. 70% ethyl alcohol) and dry it afterwards.</li>
 </ol>
 </li>
 <li>A midline neck incision is made and the soft tissues are pulled apart.</li>
 <li>The left common carotid artery (LCCA) is carefully dissected free from the surrounding nerves (without harming the vagal nerve) and a ligature is made using 6.0/7.0 string. 5.0 string can also be used.</li>
 <li>The left external carotid artery (LECA) is then separated and a second knot is made.</li>
 <li>Next, the left internal carotid artery (LICA) is isolated and a knot is prepared with a 6.0 filament.</li>
 <li>After obtaining good view of the left internal carotid artery (LICA) and the left pterygopalatine artery (LPA), both arteries are clipped, using a microvascular clip. </li>
 <li>A small hole is cut in the LCCA before it bifurcates to the LECA and the LICA. A monofilament made of 8.0 nylon coated with silicon hardener mixture (see below) is then introduced into the LICA, until it stops at the clip. Attention has to be paid not to enter the occipital artery. (Figure 1)</li>
 <li>The clipped arteries are opened while the filament is inserted into the LICA to occlude the origin of the LMCA in the circle of Willis.</li>
 <li>The third knot on the LICA is closed to fix the filament in position.</li>
 <li>The mice receive saline 0.5 mL subcutaneously as volume replenishment. For pain relief, Lidocaine gel is topically applied in the wound.</li>
 <li>If reperfusion is intended, mice stay for 30 - 90 min occlusion in a heated cage, the wound could be closed with a small suture clip. Afterwards, a second anaesthesia is performed, the third knot on the ICA is momentary opened and the filament withdrawn. </li>
 <li>The remaining sutures are shortened and the skin is adapted with a surgical suture.</li>
 <li>All animals receive a second volume replenishment as described above.</li>
 <li>Animals are put in a heated cage for two hours to control for body temperature.
	<ol>
 	<li>The animals must be checked daily after surgery for signs of discomfort. The mice could show some post surgical weight loss. They receive mashed food in a petri-dish placed on the floor to encourage eating. The food is replaced daily for seven days.</li>
	</ol>
 </li>
</ol>
2. Sham Operation
<ol>
 <li>For sham operations the filament is inserted to occlude LMCA and withdrawn immediately to allow instant reperfusion (1.8). The subsequent operation is identical to that performed on the animals undergoing cerebral ischaemia (1.9 - 1.14) including a second anaesthesia.</li>
</ol>
3. Preparation of the Filament
<ol>
 <li>Sterility of the filament should be considered. The use of sterilized equipment as well as an appropriate handling of the filament afterwards is a prerequisite for a sterile surgery. Disinfection of the filament is difficult, since many of the common sterilization methods may worsen the quality of the filament. However methods such as radiation, for example with UV light or &gamma; rays, or chemical sterilization, for example with highly reactive gases such as ethylene oxide, are applicable.</li>
 <li>8.0 nylon filament is cut into lengths of 11 mm under the microscope</li>
 <li>The filament tip must be coated completely and evenly over a length of 8 mm with a hardener mixture of Xantopren M Mucosa and Activator NF Optosil</li>
</ol>
4. Representative Results
Depending on the duration of blood flow restriction, different motor and behavioural deficits result. Both after 30 and 60 min of cerebral ischaemia, animals in most cases show decreased resistance to lateral push and circling due to disturbance in locomotion. Milder lesions manifest as a flexor position in the front limbs. These easily observable signs can be used as a basic score for the success of the operation.2 
Morphologically the lesion can be assessed using either histology or Magnetic Resonance Imaging (MRI). Sixty minutes occlusion of the middle cerebral artery produces tissue pannecrosis in an area including both the striatum and the neocortex, whereas 30 minutes of ischaemia cause mainly neuronal cell death limited to the striatum. 3 ( Figure 2) In terms of infarct volume, we expect a standard deviation lower than 30% in a set of operations. Mortality depends on the occlusion time with around 5 % after 30 min of ischaemia and 10 - 20 % after 60 min.
Another minimal invasive possibility is the use of Laser Doppler flowmetry (LDF) during the operation, which allows a direct control of its success. In an individual animal, reduction to 10 - 20 % of preocclusion values clearly indicates successful induction of focal cerebral ischemia. 4 However, LDF cannot be used as a method for interindividual comparisons, since LDF can only measure quantitative changes (in percentages) of blood flow within a small and limited tissue sample volume. It does not give information about the spatial extent of blood flow reduction. 5
There are several tests to assess behavioural aspects after stroke, including gait analysis 6,7, Rotarod 8, Pole test 9,10, adhesive removal test 11,12, staircase test 13,14, ladder rung test15,16 and Morris water maze17. In all these tests, mice subjected to MCAo perform less successfully than control animals.
<img src="/files/ftp_upload/2423/2423fig1.jpg" alt="Figure 1" /> Figure 1. Scheme of the vessel architecture supplying the brain (depicted in background) in the mouse. Different strains may show variations, for example the occipital artery sometimes leaves from the internal carotid artery.
<img src="/files/ftp_upload/2423/2423fig2.jpg" alt="Figure 2" /> Figure 2. Schematic illustration of typical lesion sizes after different time points of reperfusion in the proximal MCAo model. In the middle, the typical course of functional activity and cerebral blood flow after MCAo are depicted. (MCAo: Middle cerebral artery occlusion, LDF: Laser Doppler flow measurement)

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Experiments on animals were performed in accordance with the guidelines and regulations set forth by Landesamt fuer Gesundheit und Soziales, Berlin, Germany.

The model of transient, proximal MCA occlusion18,19 presented here mimics one of the most common types of ischaemic stroke in patients.20 Based on variable reperfusion times, the model offers different grades of damage ranging from transient ischaemic attack (TIA) to large infarcts including major parts of the ischemic hemisphere. This allows the researcher to study different pathophysiological mechanisms after stroke. 20,21
Surgery can be performed in a short time period and produces highly reproducible lesions. Nevertheless, this requires a thorough control of confounders.22 Small differences in operation technique may account for different effects on the infarct.23,24 Furthermore, due to variances in cerebral vascular anatomy, different mouse strains show a different outcome.25,26 Body temperature affects neurological damage, with hypothermia leading to smaller lesions27 and hyperthermia to more severe deficits.28 Accordingly, temperature control and maintenance is highly relevant in this model.29 In addition, blood pressure and blood gases are important confounders of outcome and need to be monitored.30,31 The use of quick and minimal invasive methods (non-invasive blood pressure measurement, suitable and easy accessible blood collection sites) is recommended. The choice of the anaesthetic is also highly important, as some may have neuroprotective effects, and/or be vasodilators, as for example Isoflurane.32 Consequently, exposure to anaesthesia should be as short as possible and standardized. We exclude animals which have undergone surgery for longer than 15 min. 
Shaving the surgical site produces microabrasions and inflammation and releases hair fragments. This may further increase inflammation and foster local infection, which may impact on stroke pathophysiology. Housing conditions, especially the use of enrichment, may affect stroke outcome and should be standardized and described in research reports. 6,33,34 The use of environmental enrichment and its effect on reproducibility is a matter of discussion.35 Another important confounder is the stroke induced risk for infection especially after longer times of ischaemia36, which leads to additional morbidity and increased mortality. 37,38 As infections become symptomatic at around day 3 to 5, this has important consequences for long term follow-up in such models.
To produce results relevant for the development of novel treatment strategies for stroke, standardization and quality control is highly important in preclinical translational stroke research. 39 "Good Laboratory Practice" 40,41 mandates:
<ol>
	<li>an appropriate and detailed description of animals used;</li>
	<li>sample size calculation and reporting on the expected effect size;</li>
	<li>inclusion and exclusion criteria, set up before the study;</li>
	<li>randomization of the allocation into groups;</li>
	<li>allocation concealment with respect to the investigators;</li>
	<li>reporting animals excluded from analysis;</li>
	<li>blinded assessment of outcome;</li>
	<li>reporting potential conflicts of interest and study funding.</li>
</ol>

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		<div>
		<table border="1">
		<thead>
		<tr>
		<th>Material Name</th>
		<th>Type</th>
		<th>Company</th>
		<th>Catalogue Number</th>
		<th>Comment</th>
		</tr>
		</thead>
		<tbody>
		
<tr>
<td>Surgical scissors (skin cut)</td>
<td>&nbsp;</td>
<td>FST</td>
<td>14028-10</td>
<td>&nbsp;</td>
<tr>
<td>2 Dumont forceps (Medical #5 straight tip)</td>
<td>&nbsp;</td>
<td>FST</td>
<td>11253-20</td>
<td>&nbsp;</td>
<tr>
<td>Spring scissors (according to Vannas)</td>
<td>&nbsp;</td>
<td>FST</td>
<td>15000-00</td>
<td>&nbsp;</td>
<tr>
<td>Applying forceps for micro clamps</td>
<td>&nbsp;</td>
<td>FST</td>
<td>00072-14</td>
<td>&nbsp;</td>
<tr>
<td>Micro vascular clamp (e.g. S&amp;G B1-V)</td>
<td>&nbsp;</td>
<td>FST</td>
<td>00396-01</td>
<td>Also Serrefine possible</td>
</tr>
<tr>
<td>2 Hemostats according to Hartmann</td>
<td>&nbsp;</td>
<td>FST</td>
<td>13002-10</td>
<td>&nbsp;</td>
<tr>
<td>Needle holder (according Olsen-Hegar or other)</td>
<td>&nbsp;</td>
<td>FST</td>
<td>12002-14</td>
<td>&nbsp;</td>
<tr>
<td>Standard anatomical forceps (for wound closure)</td>
<td>&nbsp;</td>
<td>FST</td>
<td>11000-12</td>
<td>&nbsp;</td>
<tr>
<td>5/0 sutures </td>
<td>&nbsp;</td>
<td>Suprama</td>
<td>&nbsp;</td>
<td>for vascular ligatures</td>
</tr>
<tr>
<td>6/0 sutures </td>
<td>&nbsp;</td>
<td>Suprama</td>
<td>&nbsp;</td>
<td>for skin suture, 5/0 also possible</td>
</tr>
<tr>
<td>Lidocaine (e.g. Xylocain Gel 2%)</td>
<td>&nbsp;</td>
<td>Astra Zeneca</td>
<td>&nbsp;</td>
<td>or other local pain relief</td>
</tr>
<tr>
<td>Dissecting microscope (stereo microscope), magnification 6x to max. 40x</td>
<td>&nbsp;</td>
<td>Leica Zeiss</td>
<td>MZ6 Stemi2000C</td>
<td>&nbsp;</td>
<tr>
<td>Cold light source</td>
<td>&nbsp;</td>
<td>Leica</td>
<td>KL1500</td>
<td>&nbsp;</td>
<tr>
<td>Temperature feedback controlled heating pad system</td>
<td>&nbsp;</td>
<td>FST</td>
<td>21052-00</td>
<td>With mouse pad and small probe</td>
</tr>
<tr>
<td>Anaethesia system for isoflurane</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Isoflurane</td>
<td>&nbsp;</td>
<td>Abott</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Veterinary Recovery Chamber</td>
<td>&nbsp;</td>
<td>Peco Services</td>
<td>V1200</td>
<td>Heated cage</td>
</tr>
<tr>
<td>8.0 nylon filament</td>
<td>&nbsp;</td>
<td>Suprama</td>
<td>TEL181005</td>
<td>for coating</td>
</tr>
<tr>
<td>Scalpel</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>For cutting filament in pieces</td>
</tr>
<tr>
<td>Ruler</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>To cut correct length of filament</td>
</tr>
<tr>
<td>Xantopren M Mucosa</td>
<td>&nbsp;</td>
<td>Heraeus Kulzer</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Activator Universal Plus</td>
<td>&nbsp;</td>
<td>Heraeus Kulzer</td>
<td>&nbsp;</td>
<td>Optosil - Xantopren</td>
</tr>
<tr>
<td>2 Dumont forceps (Medical #5 straight tip)</td>
<td>&nbsp;</td>
<td>FST</td>
<td>11253-20</td>
<td>&nbsp;</td>
<tr>
<td>A soft underlay for storing and grasping the uncoated filaments</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>e.g. swabs, foam, &#x2026;</td>
</tr>
<tr>
<td>Receptacle for new build filaments</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>e.g. petri dish, flexible foam,&#x2026;</td>
</tr>		</tbody>
		</table>
		</div>

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.

Watch this Scientific Journal Video about Modeling Stroke in Mice - Middle Cerebral Artery Occlusion with the Filament Model at JoVE.com

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

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91.4K Views.  Center for Stroke Research Berlin, Charité Universitätsmedizin. Filamentous occlusion of the Middle cerebral artery is a common model for studying ischemic stroke in mice.

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

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 ...

The Application Of Permanent Middle Cerebral Artery Ligation in the Mouse

Focal cerebral ischemia is among the most common type of stroke seen in patients. Due to the clinical significance there has been a prolonged effort to develop suitable animal models to study the events that unfold during ischemic insult. These techniques include transient or permanent, focal or global ischemia models using many different animal models, with the most common being rodents.
The permanent MCA ligation method which is also referred as pMCAo in the literature is used extensively as a focal ischemia model in rodents 1-6. This method was originally described for rats by Tamura et al. in 1981 7. In this protocol a craniotomy was used to access the MCA and the proximal regions were occluded by electrocoagulation. The infarcts involve mostly cortical and sometimes striatal regions depending on the location of the occlusion. This technique is now well established and used in many laboratories 8-13. Early use of this technique led to the definition and description of &#x201C;infarct core&#x201D; and &#x201C;penumbra&#x201D; 14-16, and it is often used to evaluate potential neuroprotective compounds 10, 12, 13, 17. Although the initial studies were performed in rats, permanent MCA ligation has been used successfully in mice with slight modifications 18-20 .
This model yields reproducible infarcts and increased post-survival rates. Approximately 80% of the ischemic strokes in humans happen in the MCA area 21 and thus this is a very relevant model for stroke studies. Currently, there is a paucity of effective treatments available to stroke patients, and thus there is a need for good models to test potential pharmacological compounds and evaluate physiological outcomes. This method can also be used for studying intracellular hypoxia response mechanisms in vivo. 
Here, we present the MCA ligation surgery in a C57/BL6 mouse. We describe the pre-surgical preparation, MCA ligation surgery and 2,3,5 Triphenyltetrazolium chloride (TTC) staining for quantification of infarct volumes.

Middle cerebral artery (MCA) ligation is a technique to study focal cerebral ischemia in animal models. In this method, the middle cerebral artery is exposed by craniotomy and ligated by cauterization. This method gives highly reproducible infarct volumes and increased post-operative survival rates compared to other methods available.

Focal cerebral ischemia is among the most common type of stroke seen in patients. Due to the clinical significance there has been a prolonged effort to ...

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 ...

Performing Permanent Distal Middle Cerebral with Common Carotid Artery Occlusion in Aged Rats to Study Cortical Ischemia with Sustained Disability

Stroke typically occurs in elderly people with a range of comorbidities including carotid (or other arterial) atherosclerosis, high blood pressure, obesity and diabetes. Accordingly, when evaluating therapies for stroke in animals, it is important to select a model with excellent face validity. Ischemic stroke accounts for 80% of all strokes, and the majority of these occur in the territory of the middle cerebral artery (MCA), often inducing infarcts that affect the sensorimotor cortex, causing persistent plegia or paresis on the contralateral side of the body. We demonstrate in this video a method for producing ischemic stroke in elderly rats, which causes sustained sensorimotor disability and substantial cortical infarcts. Specifically, we induce permanent distal middle cerebral artery occlusion (MCAO) in elderly female rats by using diathermy forceps to occlude a short segment of this artery. The carotid artery on the ipsilateral side to the lesion was then permanently occluded and the contralateral carotid artery was transiently occluded for 60 min. We measure the infarct size using structural T2-weighted magnetic resonance imaging (MRI) at 24 hr and 8 weeks after stroke. In this study, the mean infarct volume was 4.5% &#177; 2.0% (standard deviation) of the ipsilateral hemisphere at 24 hr (corrected for brain swelling using Gerriet&#8217;s equation, n = 5). This model is feasible and clinically relevant as it permits the induction of sustained sensorimotor deficits, which is important for the elucidation of pathophysiological mechanisms and novel treatments.

Here we present a protocol to produce permanent distal middle cerebral artery occlusion in elderly female rats with simultaneous occlusion of the carotid arteries to generate large cortical infarcts and sustained deficits. We show confirmation of the lesion size using structural MRI at 24 hr and 8 weeks after stroke.

Stroke typically occurs in elderly people with a range of comorbidities including carotid (or other arterial) atherosclerosis, high blood pressure, ...