This work was supported by Paris VI University and a Pierre Fabre Innovation grant.

All procedures were performed in accordance with European Community standards for the care and use of laboratory animals, with the approval of the local ethics committee for animal experimentation (Ile de France-Paris-Committee, Authorization 4270).
1. Anesthesia
<ol>
	<li>Infuse a lethal dose of pentobarbital (up to 1 mg/10 g body weight) intraperitoneally (27-gauge needle and 1-ml syringe) into adult mice before surgery.</li>
</ol>
2. Vessel Perfusion
<p class="jo...

<ol>
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The authors have nothing to disclose.

We describe here a reproducible protocol for the isolation of the circle of Willis. The most common cerebrovascular disorders involving the CoW are CAA-associated vasculopathies, intracranial atherosclerosis and intracranial aneurysm, all of which affect the walls of arterial vessels. The risk factors are well known, but the molecular pathogenesis of these cerebral disorders remains poorly understood and specific biological markers for predicting their occurrence are lacking. There is considerable interest in methods for...

The cerebral arterial circle (circulus arteriosus cerebri), also known as the circle of Willis (CoW), loop of Willisor Willis polygon) was first described by Thomas Willis in 1664. It is a circulatory anastomosis located around the optic chiasma and hypothalamus that can be considered as a central hub supplying blood to the brain and surrounding structures. Blood enters this structure via the internal carotid and vertebral arteries and it flows out of the circle via the interior middle and posterior cerebral arteries. Each of these arteries has left and right branches on either side of the circle. The basilar, post communicating, and anterior communicating arteries complete the circle (Figure 1 and Figure 2). The risk of impaired blood flow in any of the outflow arteries is minimized by the merging of blood entering the circle from the carotid and cerebral arteries, thereby guaranteeing that sufficient blood is supplied to the brain. This structure also serves as the main route for collateral blood flow in severe occlusive diseases of the internal carotid artery.
Several types of cerebrovascular disorders have their origin in the CoW. The most common are cerebral amyloid angiopathy (CAA)-associated vasculopathies, intracranial atherosclerosis and intracranial aneurysms. 1,2,3 These disorders may lead to hypoperfusion due to vasodilation, and intracerebral and/or subarachnoid hemorrhages ultimately translating into ischemic or hemorrhagic strokes or, at best, a transient ischemic attack. Recent advances in diagnostic procedures, including neuroimaging, possibly combined with angiography, have made it possible to diagnose these major cerebrovascular diseases clinically, without the need for a brain biopsy. Nevertheless, effective and specific treatments (pharmacological or endovascular) are currently lacking and there is therefore a need to define new molecular targets.
The identification of novel drug targets for the prevention of these diseases in humans will require animal models and ways of isolating the cerebro-vasculature including the CoW. Such models should provide evidence of and clues to the specific changes, including inflammatory changes, occurring in the walls of the large vessels in animal models of intracranial artery aneurysm, CAA or intracranial atherosclerosis. 4,5,6
We have established a method for mouse CoW isolation to facilitate studies of vessel inflammation in Alzheimer&#39;s disease (AD) and related diseases, such as CAA. This method for isolating the mouse CoW was developed for the assessment of inflammatory cerebrovascular gene expression during disease progression. Together with the detection of amyloid beta deposition within the walls of the leptomeningeal and pial arteries, this method could make it easier to determine the possible relationship between inflammatory gene expression in the cerebro-vasculature wall and A&#946;-peptide accumulation. The vascular network of the brain, including the leptomeningeal and pial in the subarachnoid space, is an extension of the large arteries forming the circle of Willis. The method described here could be used to isolate the CoW of any mouse lineage and could be used for all types of screening (e.g., gene expression, protein production and posttranslational protein modifications) on the large vessels of the mouse cerebro-vasculature.

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			<td height="46" style="height:47px;width:173px;">Dumont #55 Forceps</td>
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			<td style="width:173px;">11295-51</td>
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			<td height="46" style="height:47px;width:173px;">Hardened Fine Iris Scissors&#160;</td>
			<td style="width:173px;">Fine Science Tools</td>
			<td style="width:173px;">14090-11</td>
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			<td height="46" style="height:47px;width:173px;">Scissors - Straight / Sharp / Sharp&#160;&#160; 16.5 cm</td>
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			<td height="46" style="height:47px;width:173px;">Dumont #7b Forceps&#160;</td>
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			<td height="46" style="height:47px;width:173px;">Stereoscopic Zoom Microscope</td>
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			<td height="46" style="height:47px;width:173px;">CellBIND Surface 60mm Culture Dish</td>
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			<td height="46" style="height:47px;width:173px;">Peristaltic Pump - MINIPULS 3</td>
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			<td height="46" style="height:47px;width:173px;">Pentobarbital Sodique</td>
			<td style="width:173px;">Ceva Sant&#233; Animale</td>
			<td style="width:173px;">FR/V/2770465 3/1992</td>
			<td style="width:173px;"></td>
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protocol for isolating the mouse circle of willis

The cerebral arterial circle (circulus arteriosus cerebri) or circle of Willis (CoW) is a circulatory anastomosis surrounding the optic chiasma and hypothalamus that supplies blood to the brain and surrounding structures. It has been implicated in several cerebrovascular disorders, including cerebral amyloid angiopathy (CAA)-associated vasculopathies, intracranial atherosclerosis and intracranial aneurysms. Studies of the molecular mechanisms underlying these diseases for the identification of novel drug targets for their prevention require animal models. Some of these models may be transgenic, whereas others will involve isolation of the cerebro-vasculature, including the CoW.The method described here is suitable for CoW isolation in any mouse lineage and has considerable potential for screening (expression of genes, protein production, posttranslational protein modifications, secretome analysis, etc.) studies on the large vessels of the mouse cerebro-vasculature. It can also be used for ex vivo studies, by adapting the organ bath system developed for isolated mouse olfactory arteries.

The PBS-perfused mouse is killed and the CoW is isolated as described in section 3.2 of the protocol. When the dissection is performed correctly, the CoW should come out in one piece and should be slightly transparent due to the absence of residual blood in the vasculature.
<img alt="Figure 2" src="/files/ftp_upload/54352/54352fig2.jpg" /> 
Figure 2: The Mouse CoW after Isolation. (A) Overv...

Watch this Scientific Journal Video about Protocol for Isolating the Mouse Circle of Willis at JoVE.com

Protocol for Isolating the Mouse Circle of Willis

We describe here a reproducible protocol for isolating the mouse circle of Willis.

The cerebral arterial circle (circulus arteriosus cerebri) or circle of Willis (CoW) is a circulatory anastomosis surrounding the optic chiasma and ...

The overall goal of this dissection procedure is to isolate the murine circle of Willis to facilitate the study of the large vessels of the mouse cerebrovasculature. This method can help answer key questions in the study of cerebrovascular gene expression in various diseases that effect the cerebral vessels such as Alzheimer's disease and cerebral ameloid angiopathy. The main advantage of this technique is that the large vessels can be quickly and easily isolated without altering the vessel structure.Begin by using Iris scissors to make a four centimeter-long incision in the abdominal wall and peritoneum of a lethally anesthetized mouse just beneath the ribcage. Next, make a few millimeter long incision in the diaphragm, continuing the incision along the entire length of the ribcage to expose the pleural cavity. Lift the sternum and clamp the tip with a hemostat, resting the hemostat on the neck.Then carefully trim the adipose tissue connecting the sternum to the heart. Now pass a 15-gauge profusion needle through the left ventricle into the apex of the heart, and use scissors to cut one of the liver lobes to create an outlet for the perfusate. Perfuse the animal with 25 to 50 milliliters of PBS at a pump rate of 2.5 milliliters per minute for about ten minutes.The liver should blanch as the blood is replaced with PBS. When the fluid from the liver is completely clear, stop the perfusion. To isolate the brain, use Iris scissors to make a midline incision along the skin from the neck to the nose.Trim away the skin with the Iris scissors to expose the skull and to remove any residual muscle and adipose tissue. Next, place the Iris scissors'tips into one side of the foramen magnum and carefully slide the tips along the inner surface of the skull to the external auditory meatus. Make a similar incision on the other side of the foramen magnum, followed by a midline cut along the inner surface of the interparietal bone to the start of the sagittal suture.Plant the closed Iris scissors in the frontal bone between the eyes in the sagittal suture, and open the blades to split the skull in two. Using forceps, grasp the olfactory bulbs and use the Iris scissors to cut off the nerve connections on the ventral surface of the brain. Then immerse the brain in a 60 millimeter Petri dish of ice-cold PBS.To isolate the circle of Willis, transfer the dish onto an ice pack under a dissecting microscope and turn the brain onto its dorsal surface to visualize the circle of Willis. Use the small forceps to grasp the anterior cerebral arteries at the base of the olfactory lobes, and exert pressure to dissociate the arteries from the vessel continuum. Cut the middle cerebral arteries in the same way.Then use the sharp ends of the forceps to grasp the middle cerebral arteries and lift up the beginning of the posterior communicating arteries, disconnecting both sets of arteries from the brain. Next, lift the anterior arteries, pulling them gently over the optic chiasm in an anterior dorsal direction. Remove the superior and posterior cerebellar arteries in the same way, followed by the displacement of the basilar artery.Finally, use the forceps to gently tranfer the entire circle of Willis into a 60-millimeter Petri dish containing ice-cold PBS, and fix the vessels in place with small pins, using two forceps to carefully remove any remaining brain tissue. The circle of Willis should come out in one piece, and should be slightly transparent due to the absence of residual blood in the vasculature. The clean circle of Willis should specifically express vascular smooth muscle cell markers, such as Smooth Muscle Actin, Smooth Muscle-Myosin Heavy Chain, and Smoothelin.Neuronal markers, such as myelin oligodendrocyte glycoprotein, or microtubule-associated protein 2, by contrast, should be only barely detectable in the circle of Willis. Further, the expression of the endothelial marker, E-Selectin, in non-circle of Willis neural tissue, is very similar to that obtained for circle of Willis samples, possibly reflecting the existence of a a brain-capillary network. Once mastered, this technique can be completed in two hours if it is performed properly.While attempting this procedure, it is important to remember that mouse cerebral vessels are very fine and break easily. Thus, the dissection should be carried out very carefully, without rushing, to ensure that the entire structure is harvested in one piece. After its development, this technique paves the way for researchers in the field of inflammatory neural disease to explore cerebral vascular disorder in mouse model of Alzheimer's and related diseases such as as cerebral amyloid angiopathy.After watching this video, you should have a good understanding of how to isolate the circle of Willis from a mouse.

protocol-for-isolating-the-mouse-circle-of-willis

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12.9K visualizações.  Sorbonne Universités. The overall goal of this dissection procedure is to isolate the murine circle of Willis to facilitate the study of the large vessels of the mouse cerebrovasculature. This method can help answer key questions in the study of cerebrovascular gene expression in various diseases that effect the cerebral vessels such as Alzheimer's disease and cerebral ameloid angiopathy. The main advantage of this technique is that the large vessels can be quickly and easily isolated without altering the vessel s...