This study was supported by the NIH grant NS074559 (to C. K.). We thank all collaborators who contributed to our research articles that the present methodology report is based upon.

This protocol is approved by the Institutional Animal Care and Use Committee (IACUC) of Emory University and follows the National Institutes of Health Guideline for Care and Use of Laboratory Animals.
1. Setup
<ol>
	<li>Prepare the surgical bed on warming pad connected with heat pump at 37 &#176;C for at least 15 min before the surgery. Place a neck roll using the barrel of 3 ml syringe on the surgical bed. Prepare the anesthesia gas with 2% isoflurane in medical air.</li>
	<li>Prepare autoclaved forceps, scissors, micro needle holders, hemostat, cotton swabs and sutures. Prepare tissue glue and eye ointment.</li>
	<li>Set up the hypoxia system and temperature controllers with heating lamp and rectal probe. Prepare hypoxia gas with 2% isoflurane in 7.5% O2 balanced by 92.5% N2.</li>
	<li>One hour before surgery, mice are analgesized by subcutaneous injection of a slow-release Meloxicam (4.0 mg/kg).</li>
</ol>
2. Transient Cerebral Hypoxia-ischemia (Figure 1B)
<ol>
	<li>Anesthetize 10-13 week old male C57BL/6 mice weighing 22 to 30 g in the anesthesia induction chamber with 3% isoflurane until the animal is unresponsive to foot squeeze, and then remove the hair on right neck using an electronic shaver.</li>
	<li>Place mice on the surgical bed connected with 2% isoflurane in medical air at flow rate of 2 L/min. Secure forelimbs stretched out along neck roll at sides using medical tape.</li>
	<li>Clean the surgical site for incision with betadine followed by alcohol and then cotton swabs.</li>
	<li>Under dissecting microscope, make a 0.5 cm right-cervical incision using a straight forceps and a micro scissors about 0.2 cm lateral from midline skin.</li>
	<li>Use a pair of fine serrated forceps to pull apart the fascia and tissue to expose the right common carotid artery (RCCA). Carefully separate the RCCA from the vagal nerve using a pair of fine smooth forceps.</li>
	<li>Live knot two precut 5-0 silk suture (releasable) on the RCCA, and then sew up the skin using 4-0 Nylon monofilament suture (Figure 1C).</li>
	<li>Apply eye ointment on both eyes to prevent dryness.</li>
	<li>Quickly transfer the mice to hypoxia system and put nose and mouth in face-mask with 2% isoflurane in 7.5% O2 at flow rate of &#160; 0.5-1 L/min for 30 min.
	<ol>
		<li>During hypoxia, use temperature controllers with heating lamps to control the rectal temperature at 37.5 &#177; 0.5 &#176;C. Monitor the respiratory rate at 80-120 breaths/min. The maintenance of the body temperature above 37 &#176;C during the hypoxia is important to create consistent brain infarction. Low respiratory rate usually happens after 20 min hypoxia. Remove the face-mask and allow normal air supply if the respiratory rate drops below to 40.&#160;This&#160;takes 1-2 min and does not count&#160;into the 30 min hypoxia duration.</li>
	</ol>
	</li>
	<li>After hypoxia, transfer mice to a surgical bed and release the two sutures from RCCA. Close the wound using tissue glue, and then return mice to the cage. Exclude the animals if both of two live knots are unexpectedly released after hypoxia.</li>
	<li>Monitor the mice for 5-10 min to recover from hypoxia and anesthesia. Place the wetted food in the cage and return it to animal care facility. 
	Note: Animals showing mild to severe circling behavior at 24 hr after tHI are correlated with brain infraction. Most animals with seizure symptoms die before the&#160;24 hr timepoint&#160;after tHI.</li>
</ol>
3. Laser Speckle Contrast Imaging
Note: Although this is not an essential procedure of the tHI model, a two-dimensional laser speckle contrast imaging system16 can be used to characterize the changes of cerebral blood flow (CBF) during or after transient hypoxia-ischemia. To document the alterations of CBF under tHI, record immediately after the step 2.6. Alternatively, to compare CBF recovery after tHI insult, these procedures can be performed following the step 2.10.
<ol>
	<li>Place an anesthetized mouse&#160;in the prone position and perform a 1 cm-long midline incision on the scalp with the skull exposed but unopened.</li>
	<li>Monitor CBF in both cerebral hemispheres under a blood flow imager according to manufacturer&#8217;s protocol and start recording the cerebral blood flow immediately after the CCAO surgery (step 2.6). Continue for 50 min.</li>
	<li>Show CBF image with arbitrary units in a 16-color palette and analyze in real-time the selected regions using the MoorFLPI software following the manufacturer&#8217;s instructions (Figure 2).</li>
	<li>After recording the CBF image, close the scalp with tissue glue and return the animal to the cage.</li>
</ol>
4. tPA Administration
<ol>
	<li>Inject animals at the tail vein with the solvent or 10 mg/kg recombinant tPA (220-300 &#956;l&#160;of 1 mg/m tPA) at 0.5, 1, or 4 hr&#160;after tCCAo plus hypoxia (Figure 4).</li>
</ol>
5. Brain Damage Detection with Several Different Options
Note: To collect brain samples, euthanize the mice at 1, 4 or 24 hr after tHI.

<ol>
	<li>Perform quantification of infarct volume by in&#160;vivo 2,3,5-Triphenyltetrazolium chloride (TTC) method at 24 hrs after tHI insult as previous described.17 
	<ol>
		<li>Intraperitoneally inject animals with 1.4 M mannitol solution (~0.1 ml/g body weight) 30 min before transcardial perfusion. Transcardial perfuse mice with PBS followed by 10 ml&#160;of 2% TTC.</li>
		<li>Remove the brain of animals with surgical instruments after 10 min and place into 4% paraformaldehyde for fixation overnight and section into 1 mm thickness with a vibratome.</li>
		<li>Snap a series of four sectioned brain slides by digital microscope and quantify the infarct volume as the ratio of the infarcted area (white area in the right side) to the area of the undamaged, contralateral hemisphere using the ImageJ software.</li>
	</ol>
	</li>
	<li>Alternatively, perform thrombosis formation by immunofluorescence at 1 hr&#160;after tHI insult.
	<ol>
		<li>Freeze the fixed brain in O.C.T. compound and section the brains at 12 &#956;m thickness using a cryostat.</li>
		<li>Incubate the brain slide with rabbit anti-fibrinogen antibody (1:100) following by goat anti-rabbit Alexa Fluro 488 dye (1:200) to observe the fluorescence on a fluorescent microscope.</li>
	</ol>
	</li>
	<li>Alternatively, perform vessel obstruction by tail vein injection of 100 &#181;l&#160;2% Evans blue dye at 4 hr after tHI insult.
	<ol>
		<li>Euthanize the mice and quickly cut head to remove brains into 4% paraformaldehyde after Evans blue injection. Note: It takes 5-10 min&#160;for Evans blue circulation with blue color of both fore- and hind limbs.</li>
		<li>Section fixed brains at 100 &#956;m thickness using a sliding microtome and observe the fluorescence using a 680 nm emission filter on a fluorescent microscope.</li>
	</ol>
	</li>
</ol>

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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+two+pathophysiologies+of+focal+brain+ischemia:+implications+for+translational+stroke+research.">The two pathophysiologies of focal brain ischemia: implications for translational stroke research.</a> J. Cereb. Blood Flow Metab. 32 (7), 1310-1316 (2012).</li><li>Macrae, I. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preclinical+stroke+research--advantages+and+disadvantages+of+the+most+common+rodent+models+of+focal+ischaemia.">Preclinical stroke research--advantages and disadvantages of the most common rodent models of focal ischaemia.</a> Br. J. Pharmacol. 164 (4), 1062-1078 (2011).</li><li>Niessen, F., Hilger, T., Hoehn, M., Hossmann, K. 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Pharm. 157 (7), 1154-1156 (2009).</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>Khatri, P., 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=Revascularization+end+points+in+stroke+interventional+trials:+recanalization+versus+reperfusion+in+IMS-I.">Revascularization end points in stroke interventional trials: recanalization versus reperfusion in IMS-I.</a> Stroke. 36 (11), 2400-2403 (2005).</li><li>Rosenberg, R. D., Aird, W. 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Stroke is a major health issue of growing significance for any society with an aging population. Globally, stroke is the second-leading cause of death with an estimated 5.9 million fatal events in 2010, equivalent to 11.1% of all deaths18. Stroke is also the third-leading cause of disability-adjusted life years (DALYs) lost globally in 2010, rising from the fifth position in 199019. These epidemiological data highlight the need of more effective therapies of acute (ischemic) stroke. However, despite...

Thrombolysis and recanalization is the most effective therapy of acute ischemic stroke in clinical practice1. Yet, the majority of preclinical neuroprotection research was performed in a transient mechanic obstruction model (intraluminal suture middle cerebral artery occlusion) that produces rapid recovery of cerebral blood flow upon removal of the vascular occlusion and shows little to no benefits by tPA thrombolysis. It has been suggested that the dubious choice of stroke models contributed, at least in part, to the difficulty in translating neuroprotective therapy to patients2,3. Hence, there is an increasing call for employing tPA-responsive thromboembolic stroke models in preclinical research, but such models also have technical problems (see Discussion)4-7. Here we describe a new thrombotic stroke model based on unilateral transient hypoxic-ischemic (tHI) insult and its responses to intravenous tPA therapy8.
The tHI stroke model was developed based on the Levine procedure (permanent ligation of the unilateral common carotid artery followed by exposure to transient hypoxia in a chamber) that was invented for experiments with adult rats in 19609. The original Levine procedure faded into obscurity because it only produced variable brain damage, but the same insult caused consistent neuropathology in rodent pups when it was re-introduced by Robert Vannucci and his colleagues as a model of neonatal hypoxic-ischemic encephalopathy (HIE) in 198110. In recent years, some investigators re-adapted the Levine-Vannucci model to adult mice by adjusting the temperature in the hypoxic chamber11. It is plausible that the inconsistent brain lesions in the original Levine procedure may arise from fluctuating body temperatures of adult rodents in the hypoxic chamber. To test this hypothesis, we modified the Levine procedure by administering hypoxic gas through a facemask, while maintaining the rodent core temperature at 37 &#176;C&#160;on the surgical table12. As expected, stringent body temperature control greatly increased the reproducibility of HI-induced brain pathology. The HI insult also triggers coagulation, autophagy, and gray- and white-matter injury13. Other investigators have also used the HI model to investigate post-stroke inflammatory responses14.
A unique feature of the HI stroke model is that it closely follows the Virchow&#8217;s triad of thrombus formation, including the stasis of blood flow, endothelial injury (e.g. due to HI-induced oxidative stress), and hypercoagulability (HI-induced platelet activation) (Figure 1A)15. As such, the HI model may capture some pathophysiological mechanisms relevant to real-world ischemic stroke. With this idea in mind, we further refined the HI model with reversible ligation of the unilateral common carotid artery (therefore to create a transient HI insult), and tested its responses to tPA thrombolysis with or without Edaravone. Edaravone is a free radical scavenger already approved in Japan to treat ischemic stroke within 24 hr of onset9. Our experiments showed that as brief as 30 min transient HI triggers thrombotic infarction, and that combined tPA-Edaravone treatment confers synergistic benefits8. Here we describe detailed surgical procedures and methodological considerations of the tHI model, which can be used to optimize reperfusion treatments of acute ischemic stroke.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>adult male mice</td>
			<td>Charles River</td>
			<td>C57BL/6&#160;</td>
			<td>10~13 weeks old (22~30 g)</td>
		</tr>
		<tr>
			<td>Mobile Laboratory Animal Anesthesia System</td>
			<td>VetEquip</td>
			<td>901807</td>
			<td>anesthesia</td>
		</tr>
		<tr>
			<td>Medical air (Compressed) air tank</td>
			<td>Airgas</td>
			<td>UN1002</td>
			<td>anesthesia</td>
		</tr>
		<tr>
			<td>Isoflurane</td>
			<td>Piramal Healthcare</td>
			<td>NDC 66794-013-25</td>
			<td>anesthesia</td>
		</tr>
		<tr>
			<td>Multi-Station Lab Animal AnesthesiaSystem</td>
			<td>Surgivet</td>
			<td>V703501</td>
			<td>hypoxia system</td>
		</tr>
		<tr>
			<td>7.5% O2 balanced by 92.5% N2 tank</td>
			<td>Airgas</td>
			<td>UN1956</td>
			<td>hypoxia system</td>
		</tr>
		<tr>
			<td>Temperature Controller with heating lamp&#160;</td>
			<td>Cole Parmer&#160;</td>
			<td>EW-89000-10</td>
			<td>temperature controllers</td>
		</tr>
		<tr>
			<td>Rectal probe</td>
			<td>Cole Parmer&#160;</td>
			<td>NCI-00141PG</td>
			<td>temperature controllers</td>
		</tr>
		<tr>
			<td>Dissecting microscope&#160;</td>
			<td>Olympus&#160;</td>
			<td>SZ40</td>
			<td>surgical setup</td>
		</tr>
		<tr>
			<td>Heat pump with warming pad</td>
			<td>Gaymar&#160;</td>
			<td>TP700</td>
			<td>surgical setup</td>
		</tr>
		<tr>
			<td>Fine curved forceps (serrated)</td>
			<td>FST</td>
			<td>11370-31</td>
			<td>surgical instrument</td>
		</tr>
		<tr>
			<td>Fine curved forceps (smooth)</td>
			<td>FST</td>
			<td>11373-12</td>
			<td>surgical instrument</td>
		</tr>
		<tr>
			<td>micro scissors</td>
			<td>FST</td>
			<td>15000-03</td>
			<td>surgical instrument</td>
		</tr>
		<tr>
			<td>micro needle holders</td>
			<td>FST</td>
			<td>12060-01</td>
			<td>surgical instrument</td>
		</tr>
		<tr>
			<td>Halsted-Mosquito hemostats</td>
			<td>FST</td>
			<td>13008-12</td>
			<td>surgical instrument</td>
		</tr>
		<tr>
			<td>5-0 silk suture&#160;</td>
			<td>Harvard Apparatus</td>
			<td>624143</td>
			<td>surgical supplies</td>
		</tr>
		<tr>
			<td>4-0 Nylon monofilament suture</td>
			<td>LOOK</td>
			<td>766B</td>
			<td>surgical supplies</td>
		</tr>
		<tr>
			<td>Tissue glue</td>
			<td>Abbott Laboratories</td>
			<td>NC9855218</td>
			<td>surgical supplies</td>
		</tr>
		<tr>
			<td>Puralube Vet ointment</td>
			<td>Fisher</td>
			<td>NC0138063&#160;</td>
			<td>eye dryness prevention&#160;</td>
		</tr>
		<tr>
			<td>MoorFLPI-2 blood flow imager</td>
			<td>Moor</td>
			<td>780-nm laser source</td>
			<td>Laser Speckle Contrast Imaging</td>
		</tr>
		<tr>
			<td>Mannitol</td>
			<td>Sigma</td>
			<td>M4125</td>
			<td>in-vivo TTC</td>
		</tr>
		<tr>
			<td>2,3,5-triphenyltetrazolium chloride (TTC)&#160;</td>
			<td>Sigma</td>
			<td>T8877</td>
			<td>in-vivo TTC</td>
		</tr>
		<tr>
			<td>Vibratome</td>
			<td>Stoelting</td>
			<td>51425</td>
			<td>brain section for in-vivo TTC&#160;</td>
		</tr>
		<tr>
			<td>Digital microscope</td>
			<td>Dino-Lite</td>
			<td>AM2111</td>
			<td>whole-braina imaging</td>
		</tr>
		<tr>
			<td>O.C.T compound</td>
			<td>Sakura Finetek</td>
			<td>4583</td>
			<td></td>
		</tr>
		<tr>
			<td>goat anti-rabbit Alexa Fluro 488</td>
			<td>Invitrogen</td>
			<td>A11008</td>
			<td>Immunohistochemistry</td>
		</tr>
		<tr>
			<td>Cryostat</td>
			<td>Vibratome</td>
			<td>ultrapro 5000</td>
			<td>brain section for IHC</td>
		</tr>
		<tr>
			<td>Evans blue</td>
			<td>Sigma</td>
			<td>E2129</td>
			<td>Detecting vascular perfusion</td>
		</tr>
		<tr>
			<td>Microtome</td>
			<td>Electron Microscopy Sciences</td>
			<td>5000</td>
			<td>brain section for histology</td>
		</tr>
		<tr>
			<td>Avertin (2, 2, 2-Tribromoethanol)</td>
			<td>Sigma</td>
			<td>T48402</td>
			<td>euthanasia</td>
		</tr>
		<tr>
			<td>Fluorescent microscope</td>
			<td>Olympus</td>
			<td>DP73</td>
			<td></td>
		</tr>
	</tbody>
</table>

a thrombotic stroke model based on transient cerebral hypoxia-ischemia

Stroke research has endured many setbacks in translating neuroprotective therapies into clinical practice. In contrast, the real-world therapy (tPA thrombolysis) rarely produces benefits in mechanical occlusion-based experimental models, which dominate preclinical stroke research. This split between the bench and bedside suggests the need to employ tPA-responsive models in preclinical stroke research. To this end, a simple and tPA-reactive thrombotic stroke model is invented and described here. This model consists of transient occlusion of the unilateral common carotid artery and delivery of 7.5% oxygen through a face mask in adult mice for 30 min, while maintaining the animal rectal temperature at 37.5 &#177; 0.5 &#176;C. Although reversible ligation of the unilateral carotid artery or hypoxia each suppressed cerebral blood flow only transiently, the combination of both insults caused lasting reperfusion deficits, fibrin and platelet deposition, and large infarct in the middle cerebral artery-supplied territory. Importantly, tail-vein injection of recombinant tPA at 0.5, 1, or 4 hr post-tHI (10 mg/kg) provided time-dependent reduction of the mortality rate and infarct size. This new stroke model is simple and can be standardized across laboratories to compare experimental results. Further, it induces thrombosis without craniectomy or introducing pre-formed emboli. Given these unique merits, the tHI model is a useful addition to the repertoire of preclinical stroke research.

Two-dimensional laser speckle contrast imaging (LSCI)16 was used to compare the alterations of cerebral blood flow (CBF) by 30 min transient unilateral carotid occlusion (tCCAO), 30 min exposure to hypoxia (7.5% oxygen), and 30 min unilateral carotid ligation under hypoxia (tHI). This experiment revealed that tCCAO under normoxia suppressed the CBF on the carotid ligated hemisphere to ~50% of the baseline value, which quickly recovered to above 85% after release of the carotid occlusion (R in Figure 2A...

Watch this Scientific Journal Video about A Thrombotic Stroke Model Based On Transient Cerebral Hypoxia-ischemia at JoVE.com

A Thrombotic Stroke Model Based On Transient Cerebral Hypoxia-ischemia

Thromboembolic stroke models are vital tools for optimizing the recanalization therapy. Here we report a murine thrombotic stroke model based on transient cerebral hypoxic-ischemic (tHI) insult, which triggers thrombosis and infarction, and responds favorably to tissue plasminogen activator (tPA)-mediated fibrinolysis in a therapeutic window similar to those in stroke patients.

Stroke research has endured many setbacks in translating neuroprotective therapies into clinical practice. In contrast, the real-world therapy (tPA ...

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14.7K Views.  The Emory University School of Medicine. Thromboembolic stroke models are vital tools for optimizing the recanalization therapy. Here we report a murine thrombotic stroke model based on transient cerebral hypoxic-ischemic (tHI) insult, which triggers thrombosis and infarction, and responds favorably to tissue plasminogen activator (tPA)-mediated fibrinolysis in a therapeutic window similar to those in stroke patients. 

Video: A Thrombotic Stroke Model Based On Transient Cerebral Hypoxia-ischemia

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

A Murine Model of Subarachnoid Hemorrhage

In this video publication a standardized mouse model of subarachnoid hemorrhage (SAH) is presented. Bleeding is induced by endovascular Circle of Willis perforation (CWp) and proven by intracranial pressure (ICP) monitoring. Thereby a homogenous blood distribution in subarachnoid spaces surrounding the arterial circulation and cerebellar fissures is achieved. Animal physiology is maintained by intubation, mechanical ventilation, and continuous on-line monitoring of various physiological and cardiovascular parameters: body temperature, systemic blood pressure, heart rate, and hemoglobin saturation. Thereby the cerebral perfusion pressure can be tightly monitored resulting in a less variable volume of extravasated blood. This allows a better standardization of endovascular filament perforation in mice and makes the whole model highly reproducible. Thus it is readily available for pharmacological and pathophysiological studies in wild type and genetically altered mice.

A standardized mouse model of subarachnoid hemorrhage by intraluminal Circle of Willis perforation is described. Vessel perforation and subarachnoid bleeding are monitored by intracranial pressure monitoring. In addition various vital parameters are recorded and controlled to maintain physiologic conditions.

In this video publication a standardized mouse model of subarachnoid  hemorrhage (SAH) is presented. Bleeding is induced by endovascular Circle of  Willis ...

Excitotoxic Stimulation of Brain Microslices as an In vitro Model of Stroke

Examining molecular mechanisms involved in neuropathological conditions, such as ischemic stroke, can be difficult when using whole animal systems. As such, primary or &#39;neuronal-like&#39; cell culture systems are commonly utilized. While&#160;these systems are relatively easy to work with, and are useful model systems in which various functional outcomes (such as cell death) can be readily quantified, the examined outcomes and pathways in cultured immature neurons (such as excitotoxicity-mediated cell death pathways) are not necessarily the same as those observed in mature brain, or in intact tissue. Therefore, there is the need to develop models in which cellular mechanisms in mature neural tissue can be examined. We have developed an in vitro technique that can be used to investigate a variety of molecular pathways in intact nervous tissue. The technique described herein utilizes rat cortical tissue, but this technique can be adapted to use tissue from a variety of species (such as mouse, rabbit, guinea pig, and chicken) or brain regions (for example, hippocampus, striatum, etc.). Additionally, a variety of stimulations/treatments can be used (for example, excitotoxic, administration of inhibitors, etc.). In conclusion, the brain slice model described herein can be used to examine a variety of molecular mechanisms involved in excitotoxicity-mediated brain injury.

Excitotoxic Stimulation of Brain Microslices as an In vitro Model of Stroke

We have developed a brain slice model which can be used to examine molecular mechanisms involved in excitotoxicity-mediated brain injury.&#160;This technique generates viable mature brain tissue and reduces animal numbers required for experimentation, whilst keeping the neuronal circuitry, cellular interactions, and postsynaptic compartments partly intact.

Examining molecular mechanisms involved in neuropathological conditions, such as ischemic stroke, can be difficult when using whole animal systems. As ...

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

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

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

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

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

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

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

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

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

Simultaneous PET/MRI Imaging During Mouse Cerebral Hypoxia-ischemia

Dynamic changes in tissue water diffusion and glucose metabolism occur during and after hypoxia in cerebral hypoxia-ischemia reflecting a bioenergetics disturbance in affected cells. Diffusion weighted magnetic resonance imaging (MRI) identifies regions that are damaged, potentially irreversibly, by hypoxia-ischemia. Alterations in glucose utilization in the affected tissue may be detectable by positron emission tomography (PET) imaging of 2-deoxy-2-(18F)fluoro-&#7429;-glucose ([18F]FDG) uptake. Due to the rapid and variable nature of injury in this animal model, acquisition of both modes of data must be performed simultaneously in order to meaningfully correlate PET and MRI data. In addition, inter-animal variability in the hypoxic-ischemic injury due to vascular differences limits the ability to analyze multi-modal data and observe changes to a group-wise approach if data is not acquired simultaneously in individual subjects. The method presented here allows one to acquire both diffusion-weighted MRI and [18F]FDG uptake data in the same animal before, during, and after the hypoxic challenge in order to interrogate immediate physiological changes.

The method presented here uses simultaneous positron emission tomography and magnetic resonance imaging. In the cerebral hypoxia-ischemia model, dynamic changes in diffusion and glucose metabolism occur during and after injury. The evolving and irreproducible damage in this model necessitates simultaneous acquisition if meaningful multi-modal imaging data are to be acquired.

Dynamic changes in tissue water diffusion and glucose metabolism occur during and after hypoxia in cerebral hypoxia-ischemia reflecting a bioenergetics ...