Name: modeling stroke in mice: transient middle cerebral artery occlusion via the external carotid artery
Uploaded: 2021-05-24T14:00:00
Description: Watch this Scientific Journal Video about Modeling Stroke in Mice: Transient Middle Cerebral Artery Occlusion via the External Carotid Artery at JoVE.com

We thank all our collaboration partners of the ImmunoStroke Consortia (FOR 2879, From immune cells to stroke recovery) for suggestions and discussions. This work was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany&#39;s Excellence Strategy within the framework of the Munich Cluster for Systems Neurology (EXC 2145 SyNergy - ID 390857198) and under the grants LI-2534/6-1, LI-2534/7-1 and LL-112/1-1.

The experiments reported in this video were conducted following the national guidelines for the use of experimental animals, and the protocols were approved by the German governmental committees (Regierung von Oberbayern, Munich, Germany). Ten-week-old male C57Bl/6J mice were used and housed under controlled temperature (22 &#177; 2 &#176;C), with a 12 h light-dark cycle period and access to pelleted food and water ad libitum.
1. Preparation of the material and instruments
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	<li>Donnan, G. A., Fisher, M., Macleod, M., Davis, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stroke.">Stroke.</a> Lancet. 371 (9624), 1612-1623 (2008).</li><li>O'Collins, V. E., 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=1,026+experimental+treatments+in+acute+stroke.">1,026 experimental treatments in acute stroke.</a> Annals of Neurology. 59 (3), 467-477 (2006).</li><li>Tureyen, K., Vemuganti, R., Sailor, K. A., Dempsey, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Infarct+volume+quantification+in+mouse+focal+cerebral+ischemia:+a+comparison+of+triphenyltetrazolium+chloride+and+cresyl+violet+staining+techniques.">Infarct volume quantification in mouse focal cerebral ischemia: a comparison of triphenyltetrazolium chloride and cresyl violet staining techniques.</a> Journal of Neuroscience Methods. 139 (2), 203-207 (2004).</li><li>Zhang, Z., 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=A+new+rat+model+of+thrombotic+focal+cerebral+ischemia.">A new rat model of thrombotic focal cerebral ischemia.</a> Journal of Cerebral Blood Flow and Metabolism. 17 (2), 123-135 (1997).</li><li>Longa, E. Z., Weinstein, P. R., Carlson, S., Cummins, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reversible+middle+cerebral+artery+occlusion+without+craniectomy+in+rats.">Reversible middle cerebral artery occlusion without craniectomy in rats.</a> Stroke. 20 (1), 84-91 (1989).</li><li>Carmichael, S. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rodent+models+of+focal+stroke:+size,+mechanism,+and+purpose.">Rodent models of focal stroke: size, mechanism, and purpose.</a> NeuroRx. 2 (3), 396-409 (2005).</li><li>Engel, O., Kolodziej, S., Dirnagl, U., Prinz, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modeling+stroke+in+mice+-+middle+cerebral+artery+occlusion+with+the+filament+model.">Modeling stroke in mice - middle cerebral artery occlusion with the filament model.</a> Journal of Visualized Experiments: JoVE. (47), e2423 (2011).</li><li>Dirnagl, U., 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=A+concerted+appeal+for+international+cooperation+in+preclinical+stroke+research.">A concerted appeal for international cooperation in preclinical stroke research.</a> Stroke. 44 (6), 1754-1760 (2013).</li><li>McNutt, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Journals+unite+for+reproducibility.">Journals unite for reproducibility.</a> Science. 346 (6210), 679 (2014).</li><li>Llovera, G., 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=Results+of+a+preclinical+randomized+controlled+multicenter+trial+(pRCT):+Anti-CD49d+treatment+for+acute+brain+ischemia.">Results of a preclinical randomized controlled multicenter trial (pRCT): Anti-CD49d treatment for acute brain ischemia.</a> Science Translational Medicine. 7 (299), (2015).</li><li>Llovera, G., Liesz, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+next+step+in+translational+research:+lessons+learned+from+the+first+preclinical+randomized+controlled+trial.">The next step in translational research: lessons learned from the first preclinical randomized controlled trial.</a> Journal of Neurochemistry. 139, 271-279 (2016).</li><li>Swanson, G. M., Satariano, E. R., Satariano, W. A., Threatt, B. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Racial+differences+in+the+early+detection+of+breast+cancer+in+metropolitan+Detroit,+1978+to+1987.">Racial differences in the early detection of breast cancer in metropolitan Detroit, 1978 to 1987.</a> Cancer. 66 (6), 1297-1301 (1990).</li><li>Lourbopoulos, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inadequate+food+and+water+intake+determine+mortality+following+stroke+in+mice.">Inadequate food and water intake determine mortality following stroke in mice.</a> Journal of Cerebral Blood Flow and Metabolism. 37 (6), 2084-2097 (2017).</li><li>Clark, W. M., Lessov, N. S., Dixon, M. P., Eckenstein, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Monofilament+intraluminal+middle+cerebral+artery+occlusion+in+the+mouse.">Monofilament intraluminal middle cerebral artery occlusion in the mouse.</a> Neurological Research. 19 (6), 641-648 (1997).</li><li>Jackman, K., Kunz, A., Iadecola, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modeling+focal+cerebral+ischemia+in+vivo.">Modeling focal cerebral ischemia in vivo.</a> Methods in Molecular Biology. 793, 195-209 (2011).</li><li>Kitano, H., Kirsch, J. R., Hurn, P. D., Murphy, S. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inhalational+anesthetics+as+neuroprotectants+or+chemical+preconditioning+agents+in+ischemic+brain.">Inhalational anesthetics as neuroprotectants or chemical preconditioning agents in ischemic brain.</a> Journal of Cerebral Blood Flow and Metabolism. 27 (6), 1108-1128 (2007).</li><li>Rousselet, E., Kriz, J., Seidah, N. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mouse+model+of+intraluminal+MCAO:+cerebral+infarct+evaluation+by+cresyl+violet+staining.">Mouse model of intraluminal MCAO: cerebral infarct evaluation by cresyl violet staining.</a> Journal of Visualized Experiments: JoVE. (69), e4038 (2012).</li><li>Rha, J. H., Saver, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+impact+of+recanalization+on+ischemic+stroke+outcome:+a+meta-analysis.">The impact of recanalization on ischemic stroke outcome: a meta-analysis.</a> Stroke. 38 (3), 967-973 (2007).</li><li>Liu, J., 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=Transient+filament+occlusion+of+the+middle+cerebral+artery+in+rats:+does+the+reperfusion+method+matter+24+hours+after+perfusion.">Transient filament occlusion of the middle cerebral artery in rats: does the reperfusion method matter 24 hours after perfusion.</a> BMC Neuroscience. 13, 154 (2012).</li><li>Sommer, C. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ischemic+stroke:+experimental+models+and+reality.">Ischemic stroke: experimental models and reality.</a> Acta Neuropathologica. 133 (2), 245-261 (2017).</li><li>Jones, B. J., Roberts, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+rotarod+suitable+for+quantitative+measurements+of+motor+incoordination+in+naive+mice.">A rotarod suitable for quantitative measurements of motor incoordination in naive mice.</a> Naunyn-Schmiedebergs Archiv f&#252;r Experimentelle Pathologie und Pharmakologie. 259 (2), 211 (1968).</li><li>Bouet, V., 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=The+adhesive+removal+test:+a+sensitive+method+to+assess+sensorimotor+deficits+in+mice.">The adhesive removal test: a sensitive method to assess sensorimotor deficits in mice.</a> Nature Protocols. 4 (10), 1560-1564 (2009).</li><li>Zhang, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+test+for+detecting+long-term+sensorimotor+dysfunction+in+the+mouse+after+focal+cerebral+ischemia.">A test for detecting long-term sensorimotor dysfunction in the mouse after focal cerebral ischemia.</a> Journal of Neuroscience Methods. 117 (2), 207-214 (2002).</li><li>Schallert, T., Fleming, S. M., Leasure, J. L., Tillerson, J. L., Bland, S. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CNS+plasticity+and+assessment+of+forelimb+sensorimotor+outcome+in+unilateral+rat+models+of+stroke,+cortical+ablation,+parkinsonism+and+spinal+cord+injury.">CNS plasticity and assessment of forelimb sensorimotor outcome in unilateral rat models of stroke, cortical ablation, parkinsonism and spinal cord injury.</a> Neuropharmacology. 39 (5), 777-787 (2000).</li><li>Roth, S., Yang, J., Cramer, J., Malik, R., Liesz, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Detection+of+cytokine-induced+sickness+behavior+after+ischemic+stroke+by+an+optimized+behavioral+assessment+battery.">Detection of cytokine-induced sickness behavior after ischemic stroke by an optimized behavioral assessment battery.</a> Brain, Behavior, and Immunity. 91, 668-672 (2021).</li></ol>

The present protocol describes an experimental stroke model based on the consensus agreement of a German multicenter research consortium (&#8220;ImmunoStroke&#8221;) to establish a standardized transient MCAo model. The transient MCAo model established by introducing a silicon-coated filament through the ECA to the origin of the MCA is one of the most widely used stroke models to achieve arterial reperfusion after a delimitated occlusion period. Therefore, this procedure can be considered a translationally relevant strok...

Stroke is one of the most common causes of death and disability worldwide. Although there are mainly two distinct forms of stroke, ischemic and hemorrhagic, 80&#8211;85% of all stroke cases are ischemic1. Currently, only two treatments are available for patients with ischemic stroke: pharmacological treatment with recombinant tissue plasminogen activator (rtPA) or mechanical thrombectomy. However, due to the narrow therapeutic time window and multiple exclusion criteria, only a select number of patients can benefit from these specific treatment options. Over the last two decades, preclinical and translational stroke research has focused on the study of neuroprotective approaches. However, all compounds that reached clinical trials have so far shown no improvements for the patient2.&#160;
Since in vitro models cannot accurately reproduce all brain interactions and pathophysiological mechanisms of stroke, animal models are crucial for preclinical stroke research. However, mimicking all aspects of human ischemic stroke in a single animal model is not feasible, as ischemic stroke is a highly complex and heterogeneous disease. For this reason, different ischemic stroke models have been developed over time in different species. Photothrombosis of cerebral arterioles or permanent distal occlusion of the middle cerebral artery (MCA) are commonly used models that induce small and locally defined lesions in the neocortex3,4. Besides those, the most commonly used stroke model is probably the so-called &#8220;filament model,&#8221; in which a transient occlusion of MCA is achieved. This model consists of a transient introduction of a suture filament to the origin of the MCA, leading to an abrupt reduction of the cerebral blood flow and the subsequent large infarction of subcortical and cortical brain regions5. Although most stroke models mimic MCA occlusions 6, the &#34;filament model&#34; allows precise delimitation of the ischemic time. Reperfusion by filament removal mimics the human clinical scenario of cerebral blood flow restoration after spontaneous or therapeutic (rtPA or mechanical thrombectomy) clot lysis. To date, different modifications of this &#8220;filament model&#8221; have been described. In the most common approach, first described by Longa et al. in 19895, a silicon-coated filament is introduced via the common carotid artery (CCA) to the origin of the MCA7. Although it is a widely used approach, this model does not allow complete restoration of the blood flow during reperfusion, as the CCA is permanently ligated after removal of the filament.
Over the past decade, an increasing number of research groups have been interested in modeling stroke in mice using this &#8220;filament model.&#8221; However, the considerable variability of this model and the lack of standardization of the procedures are some of the reasons for the high variability and poor reproducibility of the experimental results and scientific findings reported so far2,8. A potential cause of the current &#8220;replication crisis,&#8221; referring to the low reproducibility among research laboratories, is the non-comparable stroke infarct volumes between research groups using the same experimental methodology9. In fact, after conducting the first preclinical randomized controlled multicenter trial study10, we were able to confirm that the lack of sufficient standardization of this experimental stroke model and the subsequent outcome parameters were the main reasons for the failure of reproducibility in preclinical studies between independent laboratories11. These drastic differences in the resulting infarct sizes, despite using the same stroke model, justifiably pose not only a threat to confirmatory research, but also for scientific collaborations due to the lack of robust and reproducible models.
In light of these challenges, we aimed to develop and describe in detail the procedure for a standardized transient MCAo model as used for the collaborative research efforts within the &#8220;ImmunoStroke&#8221; research consortium (https://immunostroke.de/). This consortium aims to understand the brain-immune interactions underlying the mechanistic principles of stroke recovery. In addition, histological and related functional methods for stroke outcome analysis are presented. All methods are based on established standard operating procedures used in all research laboratories of the ImmunoStroke consortium.

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		<tr>
			<td>45&#176; ramp</td>
			<td>H&#38;S Kunststofftechnik</td>
			<td></td>
			<td>height: 18 cm</td>
		</tr>
		<tr>
			<td>5/0 threat</td>
			<td>Pearsalls</td>
			<td>10C103000</td>
			<td></td>
		</tr>
		<tr>
			<td>5 mL Syringe</td>
			<td>Braun</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Acetic Acid</td>
			<td>Sigma Life Science</td>
			<td>695092</td>
			<td></td>
		</tr>
		<tr>
			<td>Anesthesia system for isoflurane</td>
			<td>Drager</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Bepanthen pomade</td>
			<td>Bayer</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>C57Bl/6J mice</td>
			<td>Charles River</td>
			<td>000664</td>
			<td></td>
		</tr>
		<tr>
			<td>Clamp</td>
			<td>FST</td>
			<td>12500-12</td>
			<td></td>
		</tr>
		<tr>
			<td>Clip</td>
			<td>FST</td>
			<td>18055-04</td>
			<td></td>
		</tr>
		<tr>
			<td>Clip holder</td>
			<td>FST</td>
			<td>18057-14</td>
			<td></td>
		</tr>
		<tr>
			<td>Cotons</td>
			<td>NOBA Verbondmitel Danz</td>
			<td>974116</td>
			<td></td>
		</tr>
		<tr>
			<td>Cresyl violet</td>
			<td>Sigma Life Science</td>
			<td>C5042-10G</td>
			<td></td>
		</tr>
		<tr>
			<td>Cryostat</td>
			<td>Thermo Scientific CryoStarNX70</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol 70%</td>
			<td>CLN Chemikalien Laborbedorf</td>
			<td>521005</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol 96%</td>
			<td>CLN Chemikalien Laborbedorf</td>
			<td>522078</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol 99%</td>
			<td>CLN Chemikalien Laborbedorf</td>
			<td>ETO-5000-99-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Filaments</td>
			<td>Doccol</td>
			<td>602112PK5Re</td>
			<td></td>
		</tr>
		<tr>
			<td>Fine 45 angled forceps</td>
			<td>FST</td>
			<td>11251-35</td>
			<td></td>
		</tr>
		<tr>
			<td>Fine forceps</td>
			<td>FST</td>
			<td>11252-23</td>
			<td></td>
		</tr>
		<tr>
			<td>Fine Scissors</td>
			<td>FST</td>
			<td>14094-11</td>
			<td></td>
		</tr>
		<tr>
			<td>Glue</td>
			<td>Orechseln</td>
			<td>BSI-112</td>
			<td></td>
		</tr>
		<tr>
			<td>Hardener Glue</td>
			<td>Drechseln &#38; Mehr</td>
			<td>BSI-151</td>
			<td></td>
		</tr>
		<tr>
			<td>Heating blanket</td>
			<td>FHC DC Temperature Controller</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Isoflurane</td>
			<td>Abbot</td>
			<td>B506</td>
			<td></td>
		</tr>
		<tr>
			<td>Isopentane</td>
			<td>Fluka</td>
			<td>59070</td>
			<td></td>
		</tr>
		<tr>
			<td>Ketamine</td>
			<td>Inresa Arzneimittel GmbH</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Laser Doppler</td>
			<td>Perimed</td>
			<td>PF 5010 LDPM, Periflux System 5000</td>
			<td></td>
		</tr>
		<tr>
			<td>Laser Doppler probe</td>
			<td>Perimed</td>
			<td>91-00123</td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphate Buffered Saline pH: 7.4</td>
			<td>Apotheke Innestadt Uni Munchen</td>
			<td>P32799</td>
			<td></td>
		</tr>
		<tr>
			<td>Recovery chamber</td>
			<td>Mediheat</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Roti-Histokit mounting medium</td>
			<td>Roth</td>
			<td>6638.1</td>
			<td></td>
		</tr>
		<tr>
			<td>Saline solution</td>
			<td>Braun</td>
			<td>131321</td>
			<td></td>
		</tr>
		<tr>
			<td>Scalpel</td>
			<td>Feather</td>
			<td>02.001.30.011</td>
			<td></td>
		</tr>
		<tr>
			<td>Silicon-coated filaments</td>
			<td>Doccol</td>
			<td>602112PK5Re</td>
			<td></td>
		</tr>
		<tr>
			<td>Stereomicropscope</td>
			<td>Leica</td>
			<td>M80</td>
			<td></td>
		</tr>
		<tr>
			<td>Superfrost Plus Slides</td>
			<td>Thermo Scientific</td>
			<td>J1800AMNZ</td>
			<td></td>
		</tr>
		<tr>
			<td>Vannas Spring Scissors</td>
			<td>FST</td>
			<td>15000-00</td>
			<td></td>
		</tr>
		<tr>
			<td>Xylacine</td>
			<td>Albrecht</td>
			<td></td>
			<td></td>
		</tr>
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modeling stroke in mice: transient middle cerebral artery occlusion via the external carotid artery

Stroke is the third most common cause of mortality and the leading cause of acquired adult disability in developed countries. To date, therapeutic options are limited to a small proportion of stroke patients within the first hours after stroke. Novel therapeutic strategies are being extensively investigated, especially to prolong the therapeutic time window. These current investigations include the study of important pathophysiological pathways after stroke, such as post-stroke inflammation, angiogenesis, neuronal plasticity, and regeneration. Over the last decade, there has been increasing concern about the poor reproducibility of experimental results and scientific findings among independent research groups. To overcome the so-called &#8220;replication crisis&#8221;, detailed standardized models for all procedures are urgently needed. As an effort within the &#8220;ImmunoStroke&#8221; research consortium (https://immunostroke.de/), a standardized mouse model of transient middle cerebral artery occlusion (MCAo) is proposed. This model allows the complete restoration of the blood flow upon removal of the filament, simulating the therapeutic or spontaneous clot lysis that occurs in a large proportion of human strokes. The surgical procedure of this &#8220;filament&#8221; stroke model and tools for its functional analysis are demonstrated in the accompanying video.

The model described here is a modification of the commonly used &#34;filament&#34; stroke model, which consists of introducing a silicon-coated filament through the ECA to transiently block the origin of the MCA (Figure 1). After removing the filament, only the blood flow in the ECA is permanently ceased, allowing complete recanalization of the CCA and ICA. This allows an adequate reperfusion of the brain (Figure 2), similar to the situation observed after succe...

Watch this Scientific Journal Video about Modeling Stroke in Mice: Transient Middle Cerebral Artery Occlusion via the External Carotid Artery at JoVE.com

Modeling Stroke in Mice: Transient Middle Cerebral Artery Occlusion via the External Carotid Artery

Different models of middle cerebral artery occlusion (MCAo) are used in experimental stroke research. Here, an experimental stroke model of transient MCAo via the external carotid artery (ECA) is described, which aims to mimic human stroke, in which the cerebrovascular thrombus is removed due to spontaneous clot lysis or therapy.

Stroke is the third most common cause of mortality and the leading cause of acquired adult disability in developed countries. To date, therapeutic options ...

In the filament model described here, complete restoration of blood flow and it's recording, are requirements to ensure a producible influx among mice, especially in translational stroke studies. This model has two main advantages compared to other previously described stroke models. No craniotomy is required, and a complete re-perfusion of the blood vessel is achieved.The filament model is a complex surgical intervention involving the process manipulation of different arteries. The visualization and explanation of all these are small but important steps, might accelerate the learning period of neurosurgeons. Connect the heat blanket to maintain the temperature of the operation area and the mouse body temperature during anesthesia at 37 degrees Celsius.Prepare autoclave scissors and forceps, 70%ethanol solution and dexpanthenol eye ointment, and keep several pieces of cotton and Five O coated braided polyester suture, ready to use. Prepare a 0.9%saline solution in a one milliliter syringe without a needle to keep the incision site hydrated. Prepare a holder for the laser Doppler probe by cutting the tip of a 10 microliter pipette tip.Once the mouse is completely anesthetized, place it in a prone position in the operation area. Gently insert the rectal probe to monitor the temperature throughout the surgical procedures. After disinfecting the surgical site, cut this scalp between the left ear and the eye to expose the skull bone.Next, cut and retire the temporal muscle to visualize the multiple cerebral arteries or MCA beneath the skull. Fix the outer part of the tip holding the laser Doppler probe or fiber on top of the left MCA with glue and close the skin so that the skin is glued as well. Apply two to three drops of hardener glue to speed up the process.Make sure that the laser Doppler fiber is not glued and can be easily removed from the tip holder at any time. Turn the mouse to the supine position, then put the snout into the anesthesia cone and fix the paws with tape. Disinfect the skin and hair surrounding the chest and make a two centimeter long midline incision in the neck.Use forceps to pull the skin submandibular gland and sternomastoid muscle apart. Use retractors to expose the surgical field and find the left common carotid artery or CCA. Dissect the CCA free from connective tissue and surrounding nerves without harming the vagal nerve and perform a transient ligation before the bifurcation.Dissect the external carotid artery or ECA and tie a permanent knot at the most distal visible part. Place another suture under the ECA and close to the bifurcation, then prepare a loose knot to be used later. Dissect the internal carotid artery or ICA and place a microvascular clip on it about five millimeters over the bifurcation.Make sure not to damage the vagal nerve. Then cut a small hole into the ECA between the tight and the loose ligations, ensuring not to cut the entire ECA. Introduce the filament and advance it towards the CCA.Tighten the loose ligation in the ECA around the lumen to momentarily secure the filament in that position. Removing the microvascular clip and prevent bleeding. After removing the microvascular clip, insert the filament through the ICA until the origin of the MCA is reached.Fix the filament in this position by further tightening the knot around the ECA. Record laser Doppler values before and after filament insertion. Remove the retractor and relocate the sternomastoid muscle in the submandibular gland before suturing the wound.Remove the laser Doppler probe and place the animal in a recovery chamber at 37 degrees Celsius for what one hour. Place the mouse in a prone position in the operation area with its snout in the anesthesia mask, then fix the animal's paws with tape. Insert the laser Doppler probe into the probe holder.Remove the wound suture and use forceps to pull the skin, the submandibular gland and the sternomastoid muscle apart. Use retractors to expose the surgical field. Loosen the ECA suture that tightens the filament and gently pull the filament.Avoid damaging the silicone rubber coating of the filament during the removal. Record the laser Doppler values before and after filament removal. Tightly tie the ECA suture and confirm the increase in the cerebral blood flow in the laser Doppler device.Open the transient ligation before the bifurcation from the CCA to restore the complete blood flow. Remove the retractor and relocate the sternomastoid muscle in the submandibular gland before suturing the wound. Then, place the animal in a recovery chamber at 37 degrees Celsius for one hour to recover from anesthesia.After recovery return the mice to their cages in a temperature controlled room and take care of the animals by adding wet food pellets and hydrogel in small Petri dishes on the cage floor and inject analgesia every 12 hours until day three after the surgery. Once the blood flow in the CCA is restored after removing the filament, complete re-perfusion of the brain occurs, which is similar to the situation observed after successful mechanical thrombectomy in human patients. Stroke animals presented a significant change in the composite and focal neuro score, but not in the general neuro score when compared to sham animals.Infarct volume retrieved was also performed using cresol violet staining of coronal serial brain sections 24 hours after stroke induction. The lesion area includes the somatosensory and motor cortex, as well as sub-cortical structures, such as the striatum. The infarct volume mean was 61 to 62 millimeters square, representing 48%of the effected brain hemisphere.It is important to perform an adequate dissection of the CCA, ECA and RCA without causing damage to the adjacent tissue, especially the vagus nerve, to have a good visualization of all structures, and to be able to insert the filament and occlude the MCA origin.

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Research

JoVE Journal

Neuroscience

Focal Cerebral Ischemia Model by Endovascular Suture Occlusion of the Middle Cerebral Artery in the Rat

Stroke is the leading cause of disability and the third leading cause of death in adults worldwide1. In human stroke, there exists a highly variable clinical state; in the development of animal models of focal ischemia, however, achieving reproducibility of experimentally induced infarct volume is essential. The rat is a widely used animal model for stroke due to its relatively low animal husbandry costs and to the similarity of its cranial circulation to that of humans2,3. In humans, the middle cerebral artery (MCA) is most commonly affected in stroke syndromes and multiple methods of MCA occlusion (MCAO) have been described to mimic this clinical syndrome in animal models. Because recanalization commonly occurs following an acute stroke in the human, reperfusion after a period of occlusion has been included in many of these models. In this video, we demonstrate the transient endovascular suture MCAO model in the spontaneously hypertensive rat (SHR). A filament with a silicon tip coating is placed intraluminally at the MCA origin for 60 minutes, followed by reperfusion. Note that the optimal occlusion period may vary in other rat strains, such as Wistar or Sprague-Dawley. Several behavioral indicators of stroke in the rat are shown. Focal ischemia is confirmed using T2-weighted magnetic resonance images and by staining brain sections with 2,3,5-triphenyltetrazolium chloride (TTC) 24 hours after MCAO.

Surgical induction of ischemic brain damage in the rat is a widely used model for stroke research. Here we demonstrate the induction of focal cerebral ischemia by occlusion of the middle cerebral artery. Visualization of the resulting infarct by histological staining and magnetic resonance imaging is also shown.

Stroke is the leading cause of disability and the third leading cause of death in adults worldwide1. In human stroke, there exists a highly variable ...

Lateral Chronic Cranial Window Preparation Enables In Vivo Observation Following Distal Middle Cerebral Artery Occlusion in Mice

Focal cerebral ischemia (i.e., ischemic stroke) may cause major brain injury, leading to a severe loss of neuronal function and consequently to a host of motor and cognitive disabilities. Its high prevalence poses a serious health burden, as stroke is among the principal causes of long-term disability and death worldwide1. Recovery of neuronal function is, in most cases, only partial. So far, treatment options are very limited, in particular due to the narrow time window for thrombolysis2,3. Determining methods to accelerate recovery from stroke remains a prime medical goal; however, this has been hampered by insufficient mechanistic insights into the recovery process. Experimental stroke researchers frequently employ rodent models of focal cerebral ischemia. Beyond the acute phase, stroke research is increasingly focused on the sub-acute and chronic phase following cerebral ischemia. Most stroke researchers apply permanent or transient occlusion of the MCA in mice or rats. In patients, occlusions of the MCA are among the most frequent causes of ischemic stroke4. Besides proximal occlusion of the MCA using the filament model, surgical occlusion of the distal MCA is probably the most frequently used model in experimental stroke research5. Occlusion of a distal (to the branching of the lenticulo-striate arteries) MCA branch typically spares the striatum and primarily affects the neocortex. Vessel occlusion can be permanent or transient. High reproducibility of lesion volume and very low mortality rates with respect to the long-term outcome are the main advantages of this model. Here, we demonstrate how to perform a chronic cranial window (CW) preparation lateral to the sagittal sinus, and afterwards how to surgically induce a distal stroke underneath the window using a craniotomy approach. This approach can be applied for sequential imaging of acute and chronic changes following ischemia via epi-illuminating, confocal laser scanning, and two-photon intravital microscopy.

Lateral Chronic Cranial Window Preparation Enables In Vivo Observation Following Distal Middle Cerebral Artery Occlusion in Mice

Surgical occlusion of a distal middle cerebral artery branch (MCAo) is a frequently used model in experimental stroke research. This manuscript describes the basic technique of permanent MCAo, combined with the insertion of a lateral cranial window, which offers the opportunity for longitudinal intravital microscopy in mice.

Focal cerebral ischemia (i.e., ischemic stroke) may cause major brain injury, leading to a severe loss of neuronal function and consequently to a host of ...

A Model for Encephalomyosynangiosis Treatment after Middle Cerebral Artery Occlusion-Induced Stroke in Mice

There is no effective treatment available for most patients suffering with ischemic stroke, making development of novel therapeutics imperative. The brain's ability to self-heal after ischemic stroke is limited by inadequate blood supply in the impacted area. Encephalomyosynangiosis (EMS) is a neurosurgical procedure that achieves angiogenesis in patients with moyamoya disease. It involves craniotomy with placement of a vascular temporalis muscle graft on the ischemic brain surface. EMS has never been studied in the setting of acute ischemic stroke in mice. The hypothesis driving this study is that EMS enhances cerebral angiogenesis at the cortical surface surrounding the muscle graft. The protocol shown here describes the procedure and provides initial data supporting the feasibility and efficacy of the EMS approach. In this protocol, after 60 min of transient middle cerebral artery occlusion (MCAo), mice were randomized to either MCAo or MCAo + EMS treatment. The EMS was performed 3-4 h after occlusion. The mice were sacrificed 7 or 21 days after MCAo or MCAo + EMS treatment. Temporalis graft viability was measured using nicotinamide adenine dinucleotide reduced-tetrazolium reductase assay. A mouse angiogenesis array quantified angiogenic and neuromodulating protein expression. Immunohistochemistry was used to visualize graft bonding with brain cortex and change in vessel density. The preliminary data here suggest that grafted muscle remained viable 21 days after EMS. Immunostaining showed successful graft implantation and increase in vessel density near the muscle graft, indicating increased angiogenesis. Data show that EMS increases fibroblast growth factor (FGF) and decreases osteopontin levels after stroke. Additionally, EMS after stroke did not increase mortality suggesting that protocol is safe and reliable. This novel procedure is effective and well-tolerated and has the potential to provide information of novel interventions for enhanced angiogenesis after acute ischemic stroke.

The protocol aims to provide methods for encephalomyosynangiosis-grafting of a vascular temporalis muscle flap on the pial surface of ischemic brain tissue-for the treatment of non-moyamoya acute ischemic stroke. The approach's efficacy in increasing angiogenesis is evaluated using a transient middle cerebral artery occlusion model in mice.

There is no effective treatment available for most patients suffering with ischemic stroke, making development of novel therapeutics imperative. The ...

Establishing a Transcranial Middle Cerebral Artery Occlusion Mice Model

A Modified Transcranial Middle Cerebral Artery Occlusion Model to Study Stroke Outcomes in Aged Mice

In experimental stroke research, middle cerebral artery occlusion (MCAO) with an intraluminal filament is widely used to model ischemic stroke in mice. The filament MCAO model typically exhibits a massive cerebral infarction in C57Bl/6 mice that sometimes includes brain tissue in the territory supplied by the posterior cerebral artery, which is largely due to a high incidence of posterior communicating artery atresia. This phenomenon is considered a major contributor to the high mortality rate observed in C57Bl/6 mice during long-term stroke recovery after filament MCAO. Thus, many chronic stroke studies exploit distal MCAO models. However, these models usually produce infarction only in the cortex area, and consequently, the assessment of post-stroke neurologic deficits could be a challenge. This study has established a modified transcranial MCAO model in which the MCA at the trunk is partially occluded either permanently or transiently via a small cranial window. Since the occlusion location is relatively proximal to the origin of the MCA, this model generates brain damage in both the cortex and striatum. Extensive characterization of this model has demonstrated an excellent long-term survival rate, even in aged mice, as well as readily detectable neurologic deficits. Therefore, the MCAO mouse model described here represents a valuable tool for experimental stroke research.

Author Spotlight: Innovative Techniques and Future Directions in Stroke Research 

This protocol demonstrates a unique mouse stroke model with a medium-sized infarct and an excellent survival rate. This model allows preclinical stroke researchers to extend the ischemia duration, use aged mice, and assess long-term functional outcomes.

In experimental stroke research, middle cerebral artery occlusion (MCAO) with an intraluminal filament is widely used to model ischemic stroke in mice. ...

A Model of Transient Cerebral Ischemia by Occlusion of Middle Cerebral Artery

Transient Middle Cerebral Artery Occlusion Model of Stroke

Stroke stands as a major cause of death or chronic disability globally. Nevertheless, existing optimal treatments are limited to reperfusion therapies during the acute phase of ischemic stroke. To gain insights into stroke physiopathology and develop innovative therapeutic approaches, in vivo rodent models of stroke play a fundamental role. The availability of genetically modified animals has particularly propelled the use of mice as experimental stroke models.
In stroke patients, occlusion of the middle cerebral artery (MCA) is a common occurrence. Consequently, the most prevalent experimental model involves intraluminal occlusion of the MCA, a minimally invasive technique that doesn't require craniectomy. This procedure involves inserting a monofilament through the external carotid artery (ECA) and advancing it through the internal carotid artery (ICA) until it reaches the branching point of the MCA. After a 45 min arterial occlusion, the monofilament is removed to allow reperfusion. Throughout the process, cerebral blood flow is monitored to confirm the reduction during occlusion and subsequent recovery upon reperfusion. Neurological and tissue outcomes are evaluated using behavioral tests and magnetic resonance imaging (MRI) studies.

Author Spotlight: Assessing Ischemic Stroke Damage Through Middle Cerebral Artery Occlusion Model 

This protocol describes the model of transient focal cerebral ischemia in mice through intraluminal occlusion of the middle cerebral artery. Additionally, examples of outcome assessment are shown using magnetic resonance imaging and behavioral tests.

Stroke stands as a major cause of death or chronic disability globally. Nevertheless, existing optimal treatments are limited to reperfusion therapies ...

Occlusion of Distal Middle Artery to Develop an Ischemic Stroke Mouse Model

Induction of Acute Ischemic Stroke in Mice Using the Distal Middle Artery Occlusion Technique

Ischemic stroke remains the predominant cause of mortality and functional impairment among the adult populations globally. Only a minority of ischemic stroke patients are eligible to receive intravascular thrombolysis or mechanical thrombectomy therapy within the optimal time window. Among those stroke survivors, around two-thirds suffer neurological dysfunctions over an extended period. Establishing a stable and repeatable experimental ischemic stroke model is extremely significant for further investigating the pathophysiological mechanisms and developing effective therapeutic strategies for ischemic stroke. The middle cerebral artery (MCA) represents the predominant location of ischemic stroke in humans, with the MCA occlusion serving as the frequently employed model of focal cerebral ischemia. In this protocol, we describe the methodology of establishing the distal MCA occlusion (dMCAO) model through transcranial electrocoagulation in C57BL/6 mice. Since the occlusion site is located at the cortical branch of MCA, this model generates a moderate infarcted lesion restricted to the cortex. Neurological behavioral and histopathological characterization have demonstrated visible motor dysfunction, neuron degeneration, and pronounced activation of microglia and astrocytes in this model. Thus, this dMCAO mouse model provides a valuable tool for investigating the ischemiastroke and worth of popularization.

Author Spotlight: Establishing a Reliable Distal MCA Occlusion Model in Mice for Stroke Research

Here, we present a protocol to establish a distal middle cerebral artery occlusion (dMCAO) model through transcranial electrocoagulation in C57BL/6J mice and evaluate the subsequent neurological behavior and histopathological features.

Ischemic stroke remains the predominant cause of mortality and functional impairment among the adult populations globally. Only a minority of ischemic ...

Middle Cerebral Artery Occlusion (MCAO) to Induce Stroke in a Murine Model

To begin, lay an eight to 10 weeks anesthetized C57 black six male mouse on the surgical bench. Using blunt forceps, pull out the tongue and hold it with fingers. Insert a laryngoscope into the mouth and visualize the vocal cord.Stabilize the mouse chin on the laryngoscope and hold the 20 gauge intravenous, or IV catheter with a guide wire inserted in it. Then slightly insert the guide wire into the vocal cord and slowly push the 20 gauge IV catheter into the trachea until its wing part is even with the nose tip. Once the mouse is connected to the ventilator, keep it in a lateral position with the right temporal area facing up.Maintain the rectal temperature at 37 degrees Celsius using a heating pad and a heat lamp. After locating the zygomatic arch and incising the temporal muscle, use two forceps to dissect the underlying zygomatic arch and expose the joint between the maxilla and zygomatic bones. Then using scissors, cut a three millimeter portion of the zygomatic arch and remove it.Finally, separate the masseter muscle from the skull base. Position four small retractors in different directions and expose the cranial skull base with one retractor pulling the trigeminal nerve branches laterally. Apply a saline drop to the skull above the middle cerebral artery, or MCA trunk and proximal to the rhinal cortex branch.Use an electrical grinder to thin the skull until a small fracture is visible. And with the tip of the forceps, remove the thin skull. Place a single-strand loop of black braided silk on top of the MCA.Then insert an 8-O microsurgical needle to lift the MCA trunk and tie the suture under the needle, leaving the needle's two ends on top of the silk thread loop knot. For transient middle cerebral artery occlusion, or MCAO, slightly tighten the silk thread knot under the needle to block arterial blood flow, representing MCAO onset. Use the forceps to hold the suture and slowly remove the needle at the end of the ischemia.The laser speckle contrast imaging confirmed the reduced blood supply in the right MCA. For transient MCAO after suture removal, the cerebral blood flow reperfusion was evident, and further improved after 24 hours. TTC staining of the brain after 24 hours of stroke demonstrated the generation of infarcted tissue in both the cortical and lateral striatum areas in young and aged mice.The infarct size was moderate compared to filament MCAO.

Surgical Procedure for Transient Middle Cerebral Artery Occlusion

To begin, position the anesthetized mouse on the operating table. Maintain body temperature using a rectal probe connected to a heating pad. Make an incision on the skin of the head in the direction of the sagittal suture, starting from the ears to the area between the eyes.Retract the skin and remove the periosteum on the right side of the skull. Then find the coordinates, 2.5 millimeters lateral from bregma. Apply cyanoacrylate to the doppler holder and attach it for laser-doppler flowmetry.After the glue has dried, connect the doppler probe. Then, check for the correct signal readout for assessing the cerebral blood flow. To perform artery occlusion, turn the mouse over to the supine position and fix it to the surgical table with medical tape.Then make a midline incision on the neck. Pull the skin laterally, followed by pulling away the salivary glands using retractors. This exposes the carotid territory.Identify the vascular anatomy of the common carotid artery, or CCA, the ICA, and the ECA, as well as the different arteries derived from them. For easier handling, detach CCA, followed by ECA from the connective tissue. Then cauterize the superior thyroid artery and detach ICA from the connective tissue.Check again to make sure the main arteries are fully detached from the connective tissue. Next, wrap 6-0 silk sutures around the ECA at the maxillary lingual bifurcation. Then suture around the CCA.Place a vascular clip interrupting blood circulation from the ICA. Make a small incision in the ECA close to the area where the tight knot is located. Insert the monofilament until the thick coating has completely entered the arterial lumen.Tighten the second knot to hold the monofilament inside the artery and to prevent the pressure exerted by the blood from pushing it out. Cut the ECA below the first knot and rotate the stump to orient it in the direction of the ICA. Advance the monofilament via the ICA until the point where the MCA branches out.The occlusion is reflected in an abrupt blood flow drop in the LDF readout. After 40 minutes, anesthetize the mouse again and place it back on the surgical table. Remove the stitches from the neck.After 45 minutes of occlusion, loosen the knot holding the monofilament in place. Pull slowly and gently on the filament and check that tissue recanalization occurs. Then pull out the filament and tighten the knot to prevent blood loss, clean the blood and untie the CCA knot.Ensure that there is no arterial wall damage. Remove the retractors and reposition the muscles, glands, and skin. Suture the skin using a 6-0 suture and apply disinfectant.Disconnect the Doppler probe and detach the holder. Finally, suture and disinfect the skin of the head. The outcome of the transient middle cerebral artery occlusion procedure was evaluated using in-vivo MRI neuroimaging.Lesion evolution assessed at different time points after reperfusion showed that progression of the lesion volume takes approximately two days to complete. Behavioral tests, such as grip strength test, showed a loss of strength in mice after 24 hours of transient middle cerebral artery occlusion. Also, upon stimulation in the corner test, the mice showed a preference to turn to the right side, which was ipsilateral to the lesion, indicating a successful middle cerebral artery occlusion on the right side.

Jugular Vein and Carotid Artery Canulation for Automated Blood Sampling in Mice

To begin, inject the mouse with AAV-associated vectors into the mouse brain. After three to four weeks of virus injection, shave the ventral and back areas of the neck of an anesthetized mouse. Clean the shaved areas using three iodine scrubs in rotation with 70%ethanol solution.Make a ventral incision in the skin between the shoulder blades. Afterward, place surgical gauze over the incision and position the animal in a supine state, with its head facing toward the surgeon. Then make a small vertical incision on the right side of the neck, above the clavicle, to expose the right carotid artery and jugular vein.After separating the subcutaneous tissue, expose the right external jugular vein and place the suture under the vein. Tie off the distal end of the jugular vein to halt the blood flow. Using micro forceps and scissors, make a small incision in the collapsed vein.Now, insert the venous catheter with the bevel facing downward, and move it proximally towards the superior vena cava until it reaches the right atrium. Using a 7-0 silk suture, secure the catheter to the vessel. Dissect the connective tissues to expose the right common carotid artery.Proximally, pre-place two 7-0 silk sutures'suture loops that remain unfastened at the level where the internal and external carotid arteries divide. To stop the blood flow temporarily, pull a pre-placed suture loop. Then, using micro scissors or a 27-gauge needle, create a small opening on the vessel wall.Insert the arterial catheter proximally while releasing the suture loop, and advance the catheter to reach the aorta arch, without touching the aortic valve. Use the two pre-placed sutures to fasten the catheter to the vessel. Tunnel all catheters subcutaneously, exteriorize them at the back of the neck via the pre-cut incision, and close the ventral incision.Join the catheters to the venous or arterial ports of the silicone-coated tubing connector made from 25-gauge needle tubing. After closing the ventral incision, secure the connector subcutaneously when the back skin is sealed with sutures. Using stainless steel surgical wires, fill the catheters with heparinized saline and tightly plug the ends of the catheters.To attach the animal on an automated blood collection system 24 hours postsurgery, connect the tether hook to the metal ring on the back of the neck and connect the arterial line. Once the arterial catheter is connected to the injection line, attach the venous catheters to the sampling lines. Set the injection time and dose at 0.5 milligrams per kilogram at 500 microliters per minute.Set the blood sampling time and frequency, including the sample dilution with saline. The system will automatically replenish an equal amount of saline to replace the sampled blood. Perform automated pre-injection.Next, perform an automated intravenous injection of the drug clozapine N-oxide at an injection rate of 500 microliters per minute. Then perform post-injection blood sampling. Luteinizing hormone patterns in adult Kiss1-EYFP females that received a unilateral stereotaxic injection of AAV-hM3Dq-mCherry in the arcuate nucleus are presented.Diestrus luteinizing hormone levels are generally low, but variations are usually observed because of its pulsatile release. A sharp rise in luteinizing hormone levels occurs in response to clozapine N-oxide injection. Most mCherry neurons co-localized with Kiss1-EYFP demonstrated that the viral and neuronal activation is specific to the targeted population.A luteinizing hormone pulsatile pattern of release in diestrus wild-type mice, followed by the response to an IP injection of Kisspeptin-10, is shown. Clear luteinizing hormone pulses, typical for a female in diestrus, were observed, showing low basal luteinizing hormone levels. An immediate and robust increase in luteinizing hormone was detected in response to Kisspeptin administration.

Distal Middle Artery Occlusion Procedure to Induce Ischemic Stroke in Mice

To begin, wipe the heating surgery board with 75%ethanol and set the temperature to 37 degrees Celsius. Place the anesthetized mouse in a right lateral position on the board with the head positioned away. To protect the cornea from drying, apply eye ointment.After shaving the fur from the left orbit to the left ear canal, use a depilatory cream to remove the remaining fur. Disinfect the surgical area three times with povidone iodine and 75%ethanol. Perform a toe-pinch assessment.After making a vertical incision between the left orbit and the left ear canal, retract the soft skin tissue to expose the temporal muscle. Using straight micro forceps, separate the apical and dorsal segments of the temporal muscle from the skull. Identify the Y-shaped bifurcation of the middle cerebral artery, or MCA, beneath the temporal bone.Then using an electric cranial drill, thin out the skull to make a bone window until the dura mater becomes visible. Remove the dura mater above the MCA with curved micro forceps. Using electric coagulation forceps, coagulate the artery at the site's proximal and distal to the bifurcation.Monitor the blood flow of the left MCA cortical branch in a laser speckle blood-flow meter. Then suture the muscle and the skin separately with polyglycolic acid sutures, and apply diclofenac sodium gel and mupirocin ointment to the skin incision. Place the mouse in a recovery chamber.