The authors thank Kathy Gage for her editorial support. Scheme figures were created with BioRender.com. This study was supported by funds from the Department of Anesthesiology (Duke University Medical Center) and NIH grants (NS099590, HL157354, NS117973, and NS127163).

All procedures described in this work are conducted in accordance with the NIH guidelines for the care and use of animals in research, and the protocol was approved by the Duke Institute Animal Care and Use Committee (IACUC). Young (8-10 weeks old) and aged (22 months old) male C57Bl/6 mice were used for the present study. An overview of this protocol is illustrated in Figure 1.
1. Surgical preparation
<ol>
	<li>Examine the mouse for gross abnormalities and behavioral deficits. 
	NOTE: Before surgery, it&#39;s important for surgeons to wear appropriate PPE (protective personal equipment), including surgical mask, cap, gloves, and gown.</li>
	<li>Weigh the mouse; program the ventilator (see Table of Materials) based on the body weight.</li>
	<li>Place the mouse in a 4 in x 4 in x 7 in anesthesia induction box. Turn on the oxygen flow meter (see Table of Materials), set at 30, and the nitrous oxide flow meter, set at 70. Turn on the vaporizer with 5% isoflurane.</li>
	<li>Insert the guide wire into the 20 G intravenous (IV) catheter.</li>
	<li>Take the mouse out of the induction box when its respiratory rate is reduced to 30-40 breaths per minute.</li>
	<li>Lay the mouse on the surgical bench in a supine position. Pull the mouse&#39;s tongue out and hold it with the fingers of the left hand. Insert a laryngoscope (see Table of Materials) into the animal&#39;s mouth to visualize the vocal cord.</li>
	<li>Stabilize the mouse chin on the laryngoscope using the right middle finger. Free the left hand to hold the 20 G IV catheter.</li>
	<li>Insert the guide wire slightly into the vocal cord, and then slowly push the 20 G IV catheter into the trachea until the wing part of the catheter becomes even with the nose tip. 
	NOTE: If the mouse is moving, do not insert the wire. This may cause trauma to the trachea and bleeding.</li>
	<li>Turn on the ventilator (see Table of Materials), and connect it with the 20 G IV catheter intubated in the mouse. Reduce the isoflurane to 1.5%, and ensure that both lungs are mechanically ventilated. 
	&#8203;NOTE: Do not forget to reduce the isoflurane concentration. Otherwise, the mouse will receive an overdose of anesthesia.</li>
	<li>Apply eye ointment onto both eyes and inject 5 mg/kg carprofen subcutaneously.</li>
	<li>Keep the mouse in a lateral position with the right temporal area facing up. Maintain the rectal temperature at 37 &#176;C using a heating pad (35 &#176;C) and a heat lamp controlled by a temperature regulator (see Table of Materials).</li>
	<li>Shave the surface area between the right eye and ear, and disinfect the surgical area at least three times with iodine and alcohol swabs.</li>
</ol>
2. MCAO surgery
<ol>
	<li>Open the sterile instrument package for MCAO surgery. Wear sterile gloves and make a 1 cm skin incision between the right eye and right ear using surgical scissors. 
	NOTE: Monitor skin color, body temperature, and response to toe pinch every 15 min.</li>
	<li>Dissect the underlying fascia with forceps to expose the temporal and masseter muscles. 
	NOTE: Be careful not to damage the parotid gland.</li>
	<li>Use forceps to touch the lower part of the temporal muscle and detect the location of the zygomatic arch. Carefully pull aside the branches of the facial nerve.</li>
	<li>Use the tip of a high-temperature cautery loop (see Table of Materials) to cut a 5 mm transverse incision on the temporal muscle.</li>
	<li>Use two forceps to dissect the underlying zygomatic arch and expose the joint between the maxilla and zygomatic bones.</li>
	<li>Use scissors to cut a 3 mm portion of the zygomatic arch and remove it. Separate the masseter muscle from the skull base. 
	NOTE: Be careful not to fracture the retro-orbital sinus and superficial temporal vein.</li>
	<li>Apply four small retractors positioned in different directions to expose the cranial skull base, with the trigeminal nerve branches pulled laterally by one retractor. 
	NOTE: A sulcus on the external surface of the cranial base marks the location of the lateral fissure between the frontal and temporal lobes. The MCA lies here (Figure 2A), and its trunk and branches are visible through the thin, transparent skull (Figure 2B). The relationship of this artery to other major cerebral arteries is displayed in Figure 2A.</li>
	<li>Apply a drop of 0.9% normal saline on the skull above the MCA trunk and proximal to the branch of the rhinal cortex. Use an electrical grinder to thin the skull until a small fracture is visible. 
	NOTE: Do not push the grinder against the skull, as it may penetrate the skull and injure the underlying artery.</li>
	<li>Use the tip of the forceps to lift the thinned skull and remove it. For sham mice, stop here, and do not ligate the artery. 
	NOTE: A small rectangular window across the MCA trunk is formed.</li>
	<li>Place a single-strand loop of black braided silk on top of the MCA (Figure 2C). Insert an 8-0 microsurgical needle to lift the MCA trunk, and tie the suture (see Table of Materials) under the needle, leaving both ends of the needle on the top of the silk thread loop knot (Figure 2D).</li>
	<li>For transient MCAO, tighten the silk thread knot slightly under the needle to block arterial blood flow (Figure 2E), representing MCAO onset.</li>
	<li>Use the forceps to hold the suture, and slowly remove the needle at the end of the ischemia (e.g., 60 min or longer). 
	NOTE: When the needle is removed, the silk thread knot is slipped off the MCA, and the brain is reperfused (Figure 2F).</li>
	<li>For permanent MCAO, firmly tighten the silk thread loop around the artery, and remove the needle. Cut and remove the excess suture materials.</li>
	<li>Apply a drop of 0.25% bupivacaine to the skin incision, and suture the muscle and skin separately using 6-0 nylon sutures intermittently (see Table of Materials). Apply antibiotic ointment to the surface of the skin incision. 
	NOTE: The skin incision can also be closed with sterile staples or glue.</li>
</ol>
3. Post-surgical care
<ol>
	<li>Turn the isoflurane off to awaken the mouse. Disconnect the ventilator when spontaneous respiration is restored.</li>
	<li>Transfer the mouse to a recovery chamber (see Table of Materials) with a controlled temperature.</li>
	<li>Extubate the mouse when its righting reflex is restored, or it begins to move.</li>
	<li>Closely monitor the mouse in a temperature- and humidity-controlled chamber. Return the mouse to the home cage after it gains full consciousness (recovery period ~2 h). Administer 5 mg/kg Carprofen subcutaneously daily for 3 days.</li>
</ol>
4. Laser speckle contrast imaging (LSCI)
<ol>
	<li>Six and 24 h post-MCAO, mount the anesthetized mouse on the stereotaxic frame. Shave the top of the head, and clean it with three alternating swabs of iodine and alcohol. 
	NOTE: Anesthetization was performed as mentioned in step 1.3. LSCI is also performed before MCAO.</li>
	<li>Make a 3 cm midline skin incision and dissect the skin from the skull. Apply four small needle retractors to expose the skull top.</li>
	<li>Move the laser speckle camera (see Table of Materials) above the head, and adjust the focus of the camera. Image the cerebral blood flow.</li>
</ol>
5. 2,3,5-triphenyltetrazolium chloride (TTC) staining
<ol>
	<li>Deeply anesthetize the mouse with 5% isoflurane at the end of the experiment, typically on day 1, 3, or 28 after stroke. Pinch the tail to ensure there is no pain response.</li>
	<li>Decapitate the mouse using a surgical scissor and harvest the brain. Incubate the brain in ice-cold saline for 20 min.</li>
	<li>Put the brain in a brain slicer matrix on ice and drop cold saline on the brain. Cut the brain into 1 mm slices using thin razor blades.</li>
	<li>Immerse the brain slices at the same orientation into a dish of 2% TTC solution (see Table of Materials). Keep the dish in the dark at room temperature for 15 min. 
	NOTE: Normal brain tissue becomes red and ischemic tissue remains white.</li>
	<li>Transfer the brain slices to 10% formalin for 24 h of fixation. Image the brain slices and measure the infarct area.</li>
</ol>

Establishing a Transcranial Middle Cerebral Artery Occlusion Mice Model

<ol>
	<li>Tsao, C. W., 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=Heart+disease+and+stroke+statistics-2022+update:+a+report+from+the+American+Heart+Association.">Heart disease and stroke statistics-2022 update: a report from the American Heart Association.</a> Circulation. 145 (8), e153 (2022).</li><li>Nogueira, R. 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=Thrombectomy+6+to+24+hours+after+stroke+with+a+mismatch+between+deficit+and+infarct.">Thrombectomy 6 to 24 hours after stroke with a mismatch between deficit and infarct.</a> The New England Journal of Medicine. 378 (1), 11-21 (2018).</li><li>Fisher, M., Savitz, S. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pharmacological+brain+cytoprotection+in+acute+ischaemic+stroke-renewed+hope+in+the+reperfusion+era.">Pharmacological brain cytoprotection in acute ischaemic stroke-renewed hope in the reperfusion era.</a> Nature Reviews Neurology. 18 (4), 193-202 (2022).</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>Knauss, S., 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+semiquantitative+non-invasive+measurement+of+PcomA+patency+in+C57BL/6+mice+explains+variance+in+ischemic+brain+damage+in+filament+MCAo.">A semiquantitative non-invasive measurement of PcomA patency in C57BL/6 mice explains variance in ischemic brain damage in filament MCAo.</a> Frontiers in Neuroscience. 14, 576741 (2020).</li><li>Yang, 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=Post-ischemia+common+carotid+artery+occlusion+worsens+memory+loss,+but+not+sensorimotor+deficits,+in+long-term+survived+stroke+mice.">Post-ischemia common carotid artery occlusion worsens memory loss, but not sensorimotor deficits, in long-term survived stroke mice.</a> Brain Research Bulletin. 183, 153-161 (2022).</li><li>Wang, 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=Increasing+O-GlcNAcylation+is+neuroprotective+in+young+and+aged+brains+after+ischemic+stroke.">Increasing O-GlcNAcylation is neuroprotective in young and aged brains after ischemic stroke.</a> Experimental Neurology. 339, 113646 (2021).</li><li>Jiang, M., 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=XBP1+(X-box-binding+protein-1)-dependent+O-GlcNAcylation+Is+neuroprotective+in+ischemic+stroke+in+young+mice+and+its+impairment+in+aged+mice+is+rescued+by+thiamet-G.">XBP1 (X-box-binding protein-1)-dependent O-GlcNAcylation Is neuroprotective in ischemic stroke in young mice and its impairment in aged mice is rescued by thiamet-G.</a> Stroke. 48 (6), 1646-1654 (2017).</li><li>Li, X., 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=Single-cell+transcriptomic+analysis+of+the+immune+cell+landscape+in+the+aged+mouse+brain+after+ischemic+stroke.">Single-cell transcriptomic analysis of the immune cell landscape in the aged mouse brain after ischemic stroke.</a> Journal of Neuroinflammation. 19 (1), 83 (2022).</li><li>Li, X., 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=Beneficial+effects+of+neuronal+ATF6+activation+in+permanent+ischemic+stroke.">Beneficial effects of neuronal ATF6 activation in permanent ischemic stroke.</a> Frontiers in Cellular Neuroscience. 16, 1016391 (2022).</li><li>Tamura, A., Graham, D. I., McCulloch, J., Teasdale, G. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Focal+cerebral+ischaemia+in+the+rat:+2.+Regional+cerebral+blood+flow+determined+by+[14C]iodoantipyrine+autoradiography+following+middle+cerebral+artery+occlusion.">Focal cerebral ischaemia in the rat: 2. Regional cerebral blood flow determined by [14C]iodoantipyrine autoradiography following middle cerebral artery occlusion.</a> Journal of Cerebral Blood Flow &amp; Metabolism. 1 (1), 61-69 (1981).</li><li>Tamura, A., Graham, D. I., McCulloch, J., Teasdale, G. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Focal+cerebral+ischaemia+in+the+rat:+1.+Description+of+technique+and+early+neuropathological+consequences+following+middle+cerebral+artery+occlusion.">Focal cerebral ischaemia in the rat: 1. Description of technique and early neuropathological consequences following middle cerebral artery occlusion.</a> Journal of Cerebral Blood Flow &amp; Metabolism. 1 (1), 53-60 (1981).</li></ol>

All authors have no conflict of interest.

The first transcranial MCA occlusion model was established in rats in 198111,12, and replaced by the no-craniectomy MCAO model in 19894. The initial transcranial MCA occlusion had a wide surgical field, such that the entire zygomatic arch was removed and the muscles pulled laterally. Local tissues were swollen after surgery, causing stress and decreased food intake for the animals. In our modified transcranial MCAO model, the incision is l...

Nearly 800,000 people suffer a stroke in the US every year, and most of these strokes are ischemic in nature1. Timely restoration of the cerebral blood flow with tissue plasminogen activator (tPA) and/or thrombectomy is currently the most effective treatment for stroke patients; however, the full recovery of neurologic functions in the long term is rare2,3. Thus, searching for novel stroke therapy that targets functional improvement is an intense area of research that requires clinically relevant animal models of stroke. 
The most common ischemic stroke model in rodents uses intraluminal middle cerebral artery occlusion (MCAO) to induce stroke. In this model, initially developed by Zea Longa in 1989, a nylon filament is introduced into the internal carotid artery (ICA) to block the blood flow to the middle cerebral artery (MCA)4. However, this model has limitations. First, when the filament is inserted into the ICA, the blood flow to the posterior cerebral artery (PCA) could be partially blocked as well, especially in mice. Critically, the posterior communicating artery (PcomA), a small artery that connects anterior and posterior cerebral circulation, is frequently underdeveloped in some mouse strains, such as C57Bl/6, the strain predominantly used in experimental stroke research. This patency of the PcomA is believed to contribute to the variability in lesion size in mice after stroke5. Indeed, when blood flow to the PCA drops precipitously during MCAO, and the PcomA is unable to provide sufficient collateral blood flow, the stroke infarct can expand into the territory of the PCA. Moreover, in this model, a long duration of ischemia leads to a higher chance of mortality in mice. Consequently, a short MCAO duration of 30-60 min is typically used in mice. However, most stroke patients experience a few hours of ischemia before reperfusion treatment. Thus, a mouse stroke model with an extended duration of ischemia is of high clinical relevance. 
The overall goal of this procedure is to model ischemic stroke in mice that have a medium-sized infarct and an excellent survival rate. This transcranial MCAO model addresses critical attributes of clinical stroke, as prolonged ischemia can be performed, and aged mice tolerate this model well, allowing for the long-term assessment of functional recovery.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>0.25% bupivacaine</td>
			<td>Hospira</td>
			<td>NDC 0409-1159-18</td>
			<td></td>
		</tr>
		<tr>
			<td>0.9% sodium chloride</td>
			<td>ICU Medical</td>
			<td>NDC 0990-7983-03</td>
			<td></td>
		</tr>
		<tr>
			<td>2,3,5-Triphenyltetrazolium Chloride (TTC)&#160;</td>
			<td>Sigma or any available vendor</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>20 G IV catheter</td>
			<td>BD</td>
			<td>381534</td>
			<td>20 GA 1.6 IN</td>
		</tr>
		<tr>
			<td>30 G needle</td>
			<td>BD</td>
			<td>305106</td>
			<td></td>
		</tr>
		<tr>
			<td>4-0 silk suture</td>
			<td>Look</td>
			<td>SP116</td>
			<td>Black braided silk</td>
		</tr>
		<tr>
			<td>8-0 suture with needle&#160;</td>
			<td>Ethilon</td>
			<td>2822G</td>
			<td></td>
		</tr>
		<tr>
			<td>Alcohol swabs</td>
			<td>BD</td>
			<td>326895</td>
			<td></td>
		</tr>
		<tr>
			<td>Anesthesia induction box</td>
			<td>Any suitable vendor</td>
			<td></td>
			<td>Pexiglass make&#160;</td>
		</tr>
		<tr>
			<td>Electrical grinder</td>
			<td>JSDA</td>
			<td>JD 700</td>
			<td></td>
		</tr>
		<tr>
			<td>High temperature cautery loop tip</td>
			<td>Bovie</td>
			<td>AA03</td>
			<td></td>
		</tr>
		<tr>
			<td>Isoflurane</td>
			<td>Covetrus</td>
			<td>NDC 11695-6777-2</td>
			<td></td>
		</tr>
		<tr>
			<td>Laser doppler perfusion monitor</td>
			<td>Moor Instruments</td>
			<td>moorVMS-LDF1</td>
			<td></td>
		</tr>
		<tr>
			<td>Lubricant eye ointment</td>
			<td>Bausch + Lomb</td>
			<td>339081</td>
			<td></td>
		</tr>
		<tr>
			<td>Mouse rectal probe</td>
			<td>Physitemp</td>
			<td>RET-3</td>
			<td></td>
		</tr>
		<tr>
			<td>Nitrous Oxide</td>
			<td>Airgas</td>
			<td>UN1070</td>
			<td></td>
		</tr>
		<tr>
			<td>Otoscope</td>
			<td>Welchallyn</td>
			<td>728</td>
			<td>2.5 mm Speculum</td>
		</tr>
		<tr>
			<td>Oxygen</td>
			<td>Airgas</td>
			<td>UN1072</td>
			<td></td>
		</tr>
		<tr>
			<td>Povidone-iodine</td>
			<td>CVS</td>
			<td>955338</td>
			<td></td>
		</tr>
		<tr>
			<td>Recovery box</td>
			<td>Brinsea&#160;</td>
			<td>TLC eco</td>
			<td></td>
		</tr>
		<tr>
			<td>Rimadyl (carprofen)</td>
			<td>Zoetis</td>
			<td>6100701</td>
			<td>Injectable 50 mg/mL</td>
		</tr>
		<tr>
			<td>Rodent ventilator</td>
			<td>Harvard</td>
			<td>Model 683</td>
			<td></td>
		</tr>
		<tr>
			<td>Temperature controller</td>
			<td>Physitemp</td>
			<td>TCAT-2DF&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td>Triple antibioric &#38; pain relief</td>
			<td>CVS</td>
			<td>NDC 59770-823-56</td>
			<td></td>
		</tr>
		<tr>
			<td>Vaporizer</td>
			<td>RWD</td>
			<td>R583S</td>
			<td></td>
		</tr>
	</tbody>
</table>

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.

With a direct view under a surgical microscope, it can be visually confirmed that MCA blood flow is blocked during ischemia. Our previous study showed a &#62;80% blood flow reduction in the ischemic area using a laser Doppler monitor6. In order to determine post-MCAO blood flow changes, LSCI can be used to further confirm the ischemic insult and reperfusion (Figure 1). Indeed, in Figure 3A, it is observed that the blood supply was reduced...

Watch this Scientific Journal Video about Innovative Techniques and Future Directions in Stroke Research at JoVE.com

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.

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. ...

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3.2K Views.  Duke University Medical Center. 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.

Video: Author Spotlight: Innovative Techniques and Future Directions in Stroke Research 

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 ...

Assessment of Cerebral Lateralization in Children using Functional Transcranial Doppler Ultrasound (fTCD)

There are many unanswered questions about cerebral lateralization. In particular, it remains unclear which aspects of language and nonverbal ability are lateralized, whether there are any disadvantages associated with atypical patterns of cerebral lateralization, and whether cerebral lateralization develops with age. In the past, researchers interested in these questions tended to use handedness as a proxy measure for cerebral lateralization, but this is unsatisfactory because handedness is only a weak and indirect indicator of laterality of cognitive functions1. Other methods, such as fMRI, are expensive for large-scale studies, and not always feasible with children2.
Here we will describe the use of functional transcranial Doppler ultrasound (fTCD) as a cost-effective, non-invasive and reliable method for assessing cerebral lateralization. The procedure involves measuring blood flow in the middle cerebral artery via an ultrasound probe placed just in front of the ear. Our work builds on work by Rune Aaslid, who co-introduced TCD in 1982, and Stefan Knecht, Michael Deppe and their colleagues at the University of M&uuml;nster, who pioneered the use of simultaneous measurements of left- and right middle cerebral artery blood flow, and devised a method of correcting for heart beat activity. This made it possible to see a clear increase in left-sided blood flow during language generation, with lateralization agreeing well with that obtained using other methods3.
The middle cerebral artery has a very wide vascular territory (see Figure 1) and the method does not provide useful information about localization within a hemisphere. Our experience suggests it is particularly sensitive to tasks that involve explicit or implicit speech production. The 'gold standard' task is a word generation task (e.g. think of as many words as you can that begin with the letter 'B') 4, but this is not suitable for young children and others with limited literacy skills. Compared with other brain imaging methods, fTCD is relatively unaffected by movement artefacts from speaking, and so we are able to get a reliable result from tasks that involve describing pictures aloud5,6. Accordingly, we have developed a child-friendly task that involves looking at video-clips that tell a story, and then describing what was seen.

Assessment of Cerebral Lateralization in Children using Functional Transcranial Doppler Ultrasound fTCD

Functional transcranial Doppler sonography (fTCD) is a simple and non-invasive ultrasound technique which can be used to assess the lateralization of cognitive functions, especially language, and is suitable for use with children.

There are many unanswered questions about cerebral lateralization.  In particular, it remains unclear which aspects of language and nonverbal ability are ...

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 ...

Utilizing 3D Printing Technology to Merge MRI with Histology: A Protocol for Brain Sectioning

Magnetic resonance imaging (MRI) allows for the delineation between normal and abnormal tissue on a macroscopic scale, sampling an entire tissue volume three-dimensionally. While MRI is an extremely sensitive tool for detecting tissue abnormalities, association of signal changes with an underlying pathological process is usually not straightforward. In the central nervous system, for example, inflammation, demyelination, axonal damage, gliosis, and neuronal death may all induce similar findings on MRI. As such, interpretation of MRI scans depends on the context, and radiological-histopathological correlation is therefore of the utmost importance. Unfortunately, traditional pathological sectioning of brain tissue is often imprecise and inconsistent, thus complicating the comparison between histology sections and MRI. This article presents novel methodology for accurately sectioning primate brain tissues and thus allowing precise matching between histology and MRI. The detailed protocol described in this article will assist investigators in applying this method, which relies on the creation of 3D printed brain slicers. Slightly modified, it can be easily implemented for brains of other species, including humans.

The overall goal of this protocol is to accurately align magnetic resonance imaging (MRI) image volumes with histology sections via the creation of customized 3D-printed brain holders and slicer boxes.

Magnetic resonance imaging (MRI) allows for the delineation between normal and abnormal tissue on a macroscopic scale, sampling an entire tissue volume ...

Evaluation of Bioenergetic Function in Cerebral Vascular Endothelial Cells

The integrity of the blood-brain-barrier (BBB) is critical to prevent brain injury. Cerebral vascular endothelial (CVE) cells are one of the cell types that comprise the BBB; these cells have a very high-energy demand, which requires optimal mitochondrial function. In the case of disease or injury, the mitochondrial function in these cells can be altered, resulting in disease or&#160;the opening of the BBB. In this manuscript, we introduce a method to measure mitochondrial function in CVE cells by using whole, intact cells and a bioanalyzer. A mito-stress assay is used to challenge the cells that have been perturbed, either physically or chemically, and evaluate their bioenergetic function. Additionally, this method also provides a useful way to screen new therapeutics that have direct effects on mitochondrial function. We have optimized the cell density necessary to yield oxygen consumption rates that allow for the calculation of a variety of mitochondrial parameters, including ATP production, maximal respiration, and spare capacity. We also show the sensitivity of the assay by demonstrating that the introduction of the&#160;microRNA, miR-34a, leads to a pronounced and detectable decrease in mitochondrial activity. While the data shown in this paper is optimized for the bEnd.3 cell line, we have also optimized the protocol for primary CVE cells, further suggesting the utility in preclinical and clinical models.

Endothelial cell mitochondria are critical to maintain blood-brain-barrier integrity. We introduce a protocol to measure bioenergetic function in cerebral vascular endothelial cells.

The integrity of the blood-brain-barrier (BBB) is critical to prevent brain injury. Cerebral vascular endothelial (CVE) cells are one of the cell types ...

Effects of Blast-induced Neurotrauma on Pressurized Rodent Middle Cerebral Arteries

Though there have been studies on the histopathological and behavioral effects of blast exposure, fewer have been dedicated to blast&#39;s cerebral vascular effects. Impact (i.e., non-blast) traumatic brain injury (TBI) is known to decrease pressure autoregulation in the cerebral vasculature in both humans and experimental animals. The hypothesis that blast-induced traumatic brain injury (bTBI), like impact TBI, results in impaired cerebral vascular reactivity was tested by measuring myogenic dilatory responses to reduced intravascular pressure in rodent middle cerebral arterial (MCA) segments from rats subjected to mild bTBI using an Advanced Blast Simulator (ABS) shock tube. Adult, male Sprague-Dawley rats were anesthetized, intubated, ventilated and prepared for Sham bTBI (identical manipulation and anesthesia except for blast injury) or mild bTBI. Rats were randomly assigned to receive Sham bTBI or mild bTBI followed by sacrifice 30 or 60 min post-injury. Immediately after bTBI, righting reflex (RR) suppression times were assessed, euthanasia at the time points post-injury was completed, the brain was harvested and the individual MCA segments were collected, mounted and pressurized. As the intraluminal pressure perfused through the arterial segments was reduced in 20 mmHg increments from 100 to 20 mmHg, MCA diameters were measured and recorded. With decreasing intraluminal pressure, MCA diameters steadily increased significantly above baseline in the Sham bTBI groups while MCA dilator responses were significantly reduced (p &#60; 0.05) in both bTBI groups as evidenced by the impaired, smaller MCA diameters recorded for the bTBI groups. In addition, RR suppression in the bTBI groups was significantly (p &#60; 0.05) higher than in the Sham bTBI groups. MCA&#39;s collected from the Sham bTBI groups exhibited typical vasodilatory properties to decreases in intraluminal pressure while MCA&#39;s collected following bTBI exhibited significantly impaired myogenic vasodilatory responses to reduced pressure that persisted for at least 60 min after bTBI.

Here, we present a protocol to describe methods for ex vivo vascular reactivity determination following a primary blast traumatic brain injury (bTBI) using isolated, pressurized, rodent middle cerebral arterial (MCA) segments. bTBI induction is accomplished using a shock tube, also known as an Advanced Blast Simulator (ABS) device.

Though there have been studies on the histopathological and behavioral effects of blast exposure, fewer have been dedicated to blast&#39;s cerebral ...

A Protocol for Transcranial Photobiomodulation Therapy in Mice

Transcranial photobiomodulation is a potential innovative noninvasive therapeutic approach for improving brain bioenergetics, brain function in a wide range of neurological and psychiatric disorders, and memory enhancement in age-related cognitive decline and neurodegenerative diseases. We describe a laboratory protocol for transcranial photobiomodulation therapy (PBMT) in mice. Aged BALB/c mice (18 months old) are treated with a 660 nm laser transcranially, once daily for 2 weeks. Laser transmittance data shows that approximately 1% of the incident red light on the scalp reaches a 1 mm depth from the cortical surface, penetrating the dorsal hippocampus. Treatment outcomes are assessed by two methods: a Barnes maze test, which is a hippocampus-dependent spatial learning and memory task evaluation, and measuring hippocampal ATP levels, which is used as a bioenergetics index. The results from the Barnes task show an enhancement of the spatial memory in laser-treated aged mice when compared with age-matched controls. Biochemical analysis after laser treatment indicates increased hippocampal ATP levels. We postulate that the enhancement of memory performance is potentially due to an improvement in hippocampal energy metabolism induced by the red laser treatment. The observations in mice could be extended to other animal models since this protocol could potentially be adapted to other species frequently used in translational neuroscience, such as rabbit, cat, dog, or monkey. Transcranial photobiomodulation is a safe and cost-effective modality which may be a promising therapeutic approach in age-related cognitive impairment.

Photobiomodulation therapy is an innovative noninvasive modality for the treatment of a wide range of neurological and psychiatric disorders and can also improve healthy brain function. This protocol includes a step-by-step guide to performing brain photobiomodulation in mice by transcranial light delivery, which can be adapted for use in other laboratory rodents.

Transcranial photobiomodulation is a potential innovative noninvasive therapeutic approach for improving brain bioenergetics, brain function in a wide ...

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.

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 ...

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 ...

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 ...