The authors acknowledge the facilities and the scientific and technical assistance of the Sydney Microscopy &amp; Microanalysis Research Facility (AMMRF) and the Australian Centre for Microscopy &amp; Microanalysis (ACMM) at the University of Sydney. These studies were supported by Australian National Health and Medical Research Council (NHMRC) project grant 161558 and APP1124011 (XZ).

All animal ethics and protocols were approved by The Sydney Local Health District Animal Welfare Committee and Institutional Animal Care and Use Committee (IACUC) of Tianjin Medical University. All experiments were conducted under the guidelines/regulations of Centenary Institute, University of Sydney and Tianjin Medical University
1. Induction of Cerebral Cavernous Malformations in Mouse Models
<ol>
	<li>Cross Cdh5-CreErt2; Ccm2fl/fl mice with Ccm2fl/fl&#160;to generate litters with Cdh5-CreErt2; Ccm2fl/fl&#160;(Ccm2iECKO) pups and littermate controls (Ccm2fl/fl). Cdh5-CreErt2 and Ccm2fl/fl animals have been previously described19.</li>
	<li>Dissolve 4HT in 100% ethanol and store at -80 &#176;C in aliquots of 30 &#181;L (4HT concentration: 10 mg/mL). On the day of use, dilute aliquoted 4HT in corn oil (0.5 mg/mL).</li>
	<li>Intragastrically inject 50 &#181;L of 4HT (0.5 mg/mL) to neonatal pups at P1 to induce experimental CCM lesions using an insulin syringe.</li>
</ol>
2. Sample Preparation for Micro-CT Scans
<ol>
	<li>Euthanize neonatal pups at P8 via carbon dioxide asphyxiation.</li>
	<li>Perform intra-cardiac perfusion by inserting a 29-gauge needle with 3 mL of 2% paraformaldehyde in PBS in a 10 mL syringe into the ventricle of the mouse heart. 
	CAUTION: Paraformaldehyde is toxic; wear appropriate protection.</li>
	<li>Detach the head from the body using a scissors. Remove all the skin off the head using a scissors and peel off the skull using forceps to dissect the whole brain.</li>
	<li>Take images of the brain with stereomicroscope at 7.82x magnification, 1x gain, 0.6 gamma, and 20 ms exposure time.</li>
	<li>Fix the dissected brains with 4% paraformaldehyde in PBS solution overnight. 
	CAUTION: Paraformaldehyde is toxic; wear appropriate protection.</li>
	<li>On the following day, detach hindbrains using a forceps and wash with PBS solution.</li>
	<li>Incubate the hindbrains in Lugol&#39;s iodine solution for 48 h.</li>
	<li>Following the incubation, briefly air dry the hindbrains to remove excess Lugol&#39;s iodine solution.</li>
	<li>Pack the Lugol&#39;s iodine stained hindbrains in 0.65 mL microcentrifuge tubes and seal completely with plastic paraffin film to avoid tissue shrinkage (Figure 2A).</li>
	<li>Place microcentrifuge tubes in 5 mL plastic tubes with sponges to prevent them from moving during scan (Figure 2B).</li>
</ol>
3. Micro-CT Scan of CCM in the Mouse Brain
<ol>
	<li>Vertically mount the hindbrain packed in a tube on an aluminum holder in the micro-CT system.</li>
	<li>Set the scanning parameters to 540 projections and 2 s exposure time with source conditions of 50 kV and 10 W to acquire the tomographic datasets (image resolution 9.5 &#956;m/pixel).</li>
	<li>Radiographs from the scan are reconstructed automatically by hardware-based projection reconstruction software supplied by the micro-CT system, producing an image series of 16-bit axial slices (&#34;TXM&#34; file).</li>
</ol>
4. Analysis of Micro-CT Datasets
<ol>
	<li>Open the reconstructed image file (&#34;TXM&#34; file) in the 3-D analysis software and visualize the brain using the &#34;volume rendering&#34; function.</li>
	<li>Transform the hindbrain to the desired orientation using the &#34;bounding box&#34; and &#34;clipping plane&#34; functions.</li>
	<li>Resample the transformed image in extended mode and preserve the voxel size.</li>
	<li>Create &#34;edit new label field&#34; on the transformed image (4.3) and highlight only the hindbrain using greyscale intensity.</li>
	<li>Add the highlighted areas and run &#34;label analysis&#34; to obtain measurements of the whole hindbrain (i.e., total volume and area). Export measurements in an Excel file.</li>
	<li>Visualize the hindbrain using the &#34;isosurface rendering&#34; function.</li>
	<li>Create another &#34;edit new label field&#34; on the transformed image and highlight areas with lesions using greyscale intensity.</li>
	<li>Add the highlighted areas and run &#34;label&#34; analysis to obtain measurements of the lesions within the hindbrain (i.e., total volume and area). Export measurements in an Excel file.</li>
	<li>Visualize the lesions using the &#34;generate surface&#34; and &#34;surface view&#34; functions.</li>
	<li>Snapshot the images of the hindbrain at desired orientations or generate a movie for 3-D visualization of the lesions.</li>
</ol>

<ol>
	<li>Fischer, A., Zalvide, J., Faurobert, E., Albiges-Rizo, C., Tournier-Lasserve, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cerebral+cavernous+malformations:+from+CCM+genes+to+endothelial+cell+homeostasis.">Cerebral cavernous malformations: from CCM genes to endothelial cell homeostasis.</a> Trends Mol Med. 19 (5), 302-308 (2013).</li><li>Liquori, C. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mutations+in+a+gene+encoding+a+novel+protein+containing+a+phosphotyrosine-binding+domain+cause+type+2+cerebral+cavernous+malformations.">Mutations in a gene encoding a novel protein containing a phosphotyrosine-binding domain cause type 2 cerebral cavernous malformations.</a> Am J Hum Genet. 73 (6), 1459-1464 (2003).</li><li>Laberge-le Couteulx, 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=Truncating+mutations+in+CCM1,+encoding+KRIT1,+cause+hereditary+cavernous+angiomas.">Truncating mutations in CCM1, encoding KRIT1, cause hereditary cavernous angiomas.</a> Nat Genet. 23 (2), 189-193 (1999).</li><li>Sahoo, T., 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=Mutations+in+the+gene+encoding+KRIT1,+a+Krev-1/rap1a+binding+protein,+cause+cerebral+cavernous+malformations+(CCM1).">Mutations in the gene encoding KRIT1, a Krev-1/rap1a binding protein, cause cerebral cavernous malformations (CCM1).</a> Hum Mol Genet. 8 (12), 2325-2333 (1999).</li><li>Denier, C., 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=Mutations+within+the+MGC4607+gene+cause+cerebral+cavernous+malformations.">Mutations within the MGC4607 gene cause cerebral cavernous malformations.</a> Am J Hum Genet. 74 (2), 326-337 (2004).</li><li>Bergametti, F., 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=Mutations+within+the+programmed+cell+death+10+gene+cause+cerebral+cavernous+malformations.">Mutations within the programmed cell death 10 gene cause cerebral cavernous malformations.</a> Am J Hum Genet. 76 (1), 42-51 (2005).</li><li>McDonald, D. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+mouse+model+of+cerebral+cavernous+malformations+based+on+the+two-hit+mutation+hypothesis+recapitulates+the+human+disease.">A novel mouse model of cerebral cavernous malformations based on the two-hit mutation hypothesis recapitulates the human disease.</a> Hum Mol Genet. 20 (2), 211-222 (2011).</li><li>Boulday, 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=Developmental+timing+of+CCM2+loss+influences+cerebral+cavernous+malformations+in+mice.">Developmental timing of CCM2 loss influences cerebral cavernous malformations in mice.</a> J Exp Med. 208 (9), 1835-1847 (2011).</li><li>Chan, A. C., 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=Mutations+in+2+distinct+genetic+pathways+result+in+cerebral+cavernous+malformations+in+mice.">Mutations in 2 distinct genetic pathways result in cerebral cavernous malformations in mice.</a> J Clin Invest. 121 (5), 1871-1881 (2011).</li><li>Zheng, 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=Cerebral+cavernous+malformations+arise+independent+of+the+heart+of+glass+receptor.">Cerebral cavernous malformations arise independent of the heart of glass receptor.</a> Stroke. 45 (5), 1505-1509 (2014).</li><li>McDonald, D. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fasudil+decreases+lesion+burden+in+a+murine+model+of+cerebral+cavernous+malformation+disease.">Fasudil decreases lesion burden in a murine model of cerebral cavernous malformation disease.</a> Stroke. 43 (2), 571-574 (2012).</li><li>Maddaluno, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=EndMT+contributes+to+the+onset+and+progression+of+cerebral+cavernous+malformations.">EndMT contributes to the onset and progression of cerebral cavernous malformations.</a> Nature. 498 (7455), 492-496 (2013).</li><li>Gibson, C. C., 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=Strategy+for+identifying+repurposed+drugs+for+the+treatment+of+cerebral+cavernous+malformation.">Strategy for identifying repurposed drugs for the treatment of cerebral cavernous malformation.</a> Circulation. 131 (3), 289-299 (2015).</li><li>Choi, J. 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=Micro-CT+Imaging+Reveals+Mekk3+Heterozygosity+Prevents+Cerebral+Cavernous+Malformations+in+Ccm2-Deficient+Mice.">Micro-CT Imaging Reveals Mekk3 Heterozygosity Prevents Cerebral Cavernous Malformations in Ccm2-Deficient Mice.</a> PLoS One. 11 (8), 0160833 (2016).</li><li>Zhou, 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=Cerebral+cavernous+malformations+arise+from+endothelial+gain+of+MEKK3-KLF2/4+signalling.">Cerebral cavernous malformations arise from endothelial gain of MEKK3-KLF2/4 signalling.</a> Nature. 532 (7597), 122-126 (2016).</li><li>Metscher, B. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=MicroCT+for+comparative+morphology:+simple+staining+methods+allow+high-contrast+3D+imaging+of+diverse+non-mineralized+animal+tissues.">MicroCT for comparative morphology: simple staining methods allow high-contrast 3D imaging of diverse non-mineralized animal tissues.</a> BMC Physiol. 9, 11 (2009).</li><li>Johnson, J. T., 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=Virtual+histology+of+transgenic+mouse+embryos+for+high-throughput+phenotyping.">Virtual histology of transgenic mouse embryos for high-throughput phenotyping.</a> PLoS Genet. 2 (4), 61 (2006).</li><li>Anderson, R., Maga, A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Novel+Procedure+for+Rapid+Imaging+of+Adult+Mouse+Brains+with+MicroCT+Using+Iodine-Based+Contrast.">A Novel Procedure for Rapid Imaging of Adult Mouse Brains with MicroCT Using Iodine-Based Contrast.</a> PLoS One. 10 (11), 0142974 (2015).</li><li>Zheng, 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=Dynamic+regulation+of+the+cerebral+cavernous+malformation+pathway+controls+vascular+stability+and+growth.">Dynamic regulation of the cerebral cavernous malformation pathway controls vascular stability and growth.</a> Dev Cell. 23 (2), 342-355 (2012).</li></ol>

The authors have nothing to disclose.

CCM is a common vascular malformation that affects up to 0.5% of individuals1. CCM can occur in sporadic or familial form. Patient prognosis is often unclear as CCM lesions can rupture unexpectedly to cause stroke and other neurological consequences. Currently, the only treatment option is to surgically remove lesions, which are accompanied by high risk.
Human CCM conditions have recently been reproduced in animal models7,8,9,10. These models provide invaluable tools to investigate mechanisms involved in CCM disease. An accurate, efficient, and quantitative analysis method will help to harness the full value of these models.
We have recently developed a micro-CT method to image CCM lesions in mouse models using osmium tetraoxide as a contrasting agent14. In the current study, we have subsequently used Lugol&#39;s iodine solution to enhance the contrast of brain tissue to detect lesions. Lugol&#39;s iodine solution is less toxic, non-destructive, and cheaper compared to osmium tetraoxide. Hence, the samples can be reused for other purposes, such as histology after Lugol&#39;s iodine solution is washed away.
Our micro-CT method could produce sufficient image quality to detect CCM lesions in the mouse brain. The sample preparation is straightforward and does not require highly specialized techniques. This method can provide high-resolution projections with a scan time of approximately one hour. Combining datasets from micro-CT scans and 3-D analysis software is a powerful way to generate a 3-D global view of CCM lesions in brain. The quantitative and qualitative representation of lesions relative to brain anatomy is easily achieved. Compared to histology-based 3-D reconstruction, our method is highly time- and cost-effective and produces much more accurate 3-D representations.
However, there are also limitations and critical steps to be considered. Firstly, the method requires a micro-CT system, which is highly specialized equipment and may not be readily available. Secondly, dissecting the neonatal mouse brain can be quite challenging due to the softness and size of the brain tissue. It is very important not to damage the brain during dissection in order to acquire accurate measurements and visualization of the CCM lesions in the brain. Lastly, sample preparation for micro-CT scan is critical. Lugol&#39;s iodine stained brains must be packed completely to avoid tissue shrinkage due to evaporation. Also, samples must be placed securely during the micro-CT scan. Any movement during the scan will alter the quality of the scan and hence the quantification and visualization.
We have applied our method only in fixed neonatal mouse brains. However, this method has the capacity to be used for other studies involving different samples and may serve as an exciting and novel tool for other vascular malformation research.

CCM are&#160;thin walled, dilated vascular malformations in the brain with prevalence of up to 0.5% in the human population1. CCM can be inherited as a dominant disorder due to loss-of-function mutations in one of three genes: CCM1 (aka Krit1), CCM2, and CCM3 (also called PDCD10)2,3,4,5,6. These genes are present in a single signaling complex.
Various models have been developed to model human CCM disease and to understand the downstream pathways of CCM genes that are responsible for CCM7,8,9,10. The most robust model is to conditionally delete any one of the Ccm genes with tamoxifen-inducible Cdh5-CreERT2 at P1 in newborn pups8,10. These pups develop CCM lesions in the brain from P6 onward and are expected to be an ideal model for pre-clinical studies in search for mechanisms and therapeutic agents in treating CCM diseases.
CCM lesion burden in mouse brain has been measured primarily by histology-based methods, an approach that is extremely time-consuming and subject to investigator bias10,11,12. MRI based methods have been used to assess CCM lesion burden in the adult mouse model9,13. However, a highly specialized small animal MRI instrument and long scan-time of several hours to overnight is required to achieve a satisfactory resolution to identifying CCM lesions. Also, whether MRI can be used to detect CCM lesions in neonatal mice has not been reported and resolution may limit sensitivity.
We have recently developed a micro-CT technique to image and analyze CCM lesion14,15. This high-resolution, time and cost-effective method dramatically boosted the value of the CCM disease model in mechanistic and therapeutic studies. Contrast-enhancing, whole mount staining methods have been used for micro-CT imaging of soft tissues and mouse embryos16,17. Previously, we have used an osmium-based staining to enhance contrast for micro-CT imaging of CCM lesions in brain14. In this paper, we used a less toxic, non-destructive, and cost-efficient reagent, an iodine based Lugol&#39;s solution, to enhance contrast for micro-CT imaging. Iodine can diffuse throughout the brain and has a high affinity for blood18.
The detailed protocol is presented here for the induction of CCM lesions in a neonatal mouse model along with the imaging and analysis of CCM lesions with a contrast-based micro-CT. This micro-CT based method provides quantitative global measurement of CCM lesion volume, accurately identifies the number and 3-D location of CCM lesions in the mouse brain, and greatly reduces the cost and time required to phenotype these animals.

<table >
	
		
		
		
		
	
	<tbody>
		<tr >
			<td >4-hydroxy tamoxifen</td>
			<td >Sigma-Aldrich</td>
			<td >H6278</td>
			<td >To activate Cdh5-CreErt2</td>
		</tr>
		<tr >
			<td >Corn oil</td>
			<td >Sigma-Aldrich</td>
			<td >C8267-500ML</td>
			<td >To dilute 4-hydroxy tamoxifen</td>
		</tr>
		<tr >
			<td >Stereomicroscope</td>
			<td >Leica</td>
			<td >M205FA</td>
			<td >To take macroscopic images</td>
		</tr>
		<tr >
			<td >Lugol&#39;s Iodine solution</td>
			<td >Sigma-Aldrich</td>
			<td >L6146</td>
			<td >To stain samples for contrast micro-CT</td>
		</tr>
		<tr >
			<td >Plastic paraffin film</td>
			<td >Parafilm</td>
			<td >PM992</td>
			<td >To package samples</td>
		</tr>
		<tr >
			<td >Micro-CT</td>
			<td >Xradia</td>
			<td >MicroXCT-400</td>
			<td >Micro-CT</td>
		</tr>
		<tr >
			<td >3D rendering software</td>
			<td >FEI Visualization Science group</td>
			<td >Avizo 3D image processing software</td>
			<td >To analyse micro-CT scans</td>
		</tr>
	</tbody>
</table>

induction and micro-ct imaging of cerebral cavernous malformations in mouse model

Mutations in the CCM1 (aka KRIT1), CCM2, or CCM3 (aka PDCD10) gene cause cerebral cavernous malformation (CCM) in humans. Mouse models of CCM disease have been established by tamoxifen induced deletion of Ccm genes in postnatal animals. These mouse models provide invaluable tools to investigate molecular mechanism and therapeutic approaches for CCM disease. An accurate and quantitative method to assess lesion burden and progression is essential to harness the full value of these animal models. Here, we demonstrate the induction of CCM disease in a mouse model and the use of the contrast enhanced X-ray micro computed tomography (micro-CT) method to measure CCM lesion burden in mouse brains. At postnatal day 1 (P1), we used 4-hydroxytamoxifen (4HT) to activate Cre recombinase activity from the Cdh5-CreErt2 transgene to cleave the floxed allele of Ccm2. CCM lesions in mouse brains were analyzed at P8. For micro-CT, iodine based Lugol&#39;s solution was used to enhance contrast in brain tissue. We have optimized the scan parameters and utilized a voxel dimension of 9.5 &#181;m, which lead to a minimum feature size of approximately 25 &#181;m. This resolution is sufficient to measure CCM lesion volume and number globally and accurately, and provide high-quality 3-D mapping of CCM lesions in mouse brains. This method enhances the value of the established mouse models to study the molecular basis and potential therapies for CCM and other cerebrovascular diseases.

A single injection of 4HT at P1 was sufficient to induce CCM lesions in the cerebellum. Lugol&#39;s iodine contrasted micro-CT sufficiently detected CCM lesions and could quantify its volume and number. Utilizing the optimized micro-CT, we imaged CCM lesions in the hindbrains of Ccm2iECKO mice. Scanned X-ray images were reconstructed to produce 3-D images of the mouse brain, which allowed visualization of entire lesions in the brain parenchyma at different depths and orientations, and assessment of the structure and 3-D location of lesions in the brain. Importantly, this image dataset can also be used for efficient and accurate quantification of lesion sizes and lesion numbers.
Figure 1 shows successful induction of CCM lesions in the cerebellum of Ccm2iECKO (B) but not in littermate controls (Ccm2fl/fl) (A) at P8.
Figure 2 shows a packed sample for micro-CT scan (A-B), and representative reconstructed images from the micro-CT scan of control (Ccm2fl/fl)&#160;(C) and Ccm2iECKO (D-E). Figure 2E&#39; shows marked lesions in Ccm2iECKO.
Figure 3 shows a rendered 3-D image of a Ccm2iECKO brain with lesions (A-B).Adjacent Table shows an example of quantitative output of the labeled individual lesions.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/56476/56476fig1.jpg" /> 
Figure 1: Induction of CCM lesions in neonatal mouse. Macroscopic images of Ccm2fl/fl (A) and Ccm2iECKO (B) brains at postnatal day 8. Scale bars (white), 5 mm. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56476/56476fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/56476/56476fig2.jpg" /> 
Figure 2: Sample preparation and reconstructed 2D images. Sample packed in a microcentrifuge tube (A) and 5 mL tubes (B). Green arrow shows the sample. Representative images of Ccm2fl/fl (C) and Ccm2iECKO (D-E) brains. (E&#39;) Marked lesions in Ccm2iECKO brain. Scale bars (white), 1 mm. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56476/56476fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/56476/56476fig3.jpg" /> 
Figure 3: Rendered 3-D images. Rendered image of Ccm2iECKO brain with lesions (A) and lesions only (B). Lesions are marked in red. Table on the right shows an example of qualitative output of individually marked lesions. Scale bars (white), 1 mm.&#160;<a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56476/56476fig3large.jpg" style="font-size: 14px;" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about Induction and Micro-CT Imaging of Cerebral Cavernous Malformations in Mouse Model at JoVE.com

Induction and Micro-CT Imaging of Cerebral Cavernous Malformations in Mouse Model

This protocol demonstrates the induction of cerebral cavernous malformation disease in a mouse model and uses contrast enhanced micro computed tomography to measure lesion burden. This method enhances the value of established mouse models to study the molecular basis and potential therapies for cerebral cavernous malformation and other cerebrovascular diseases.

Mutations in the CCM1 (aka KRIT1), CCM2, or CCM3 (aka PDCD10) gene cause cerebral cavernous malformation (CCM) in humans. Mouse models of CCM disease have ...

induction-micro-ct-imaging-cerebral-cavernous-malformations-mouse

Nanyang Technological University

Research

JoVE Journal

Medicine

10.8K Views.  Centenary Institute. This protocol demonstrates the induction of cerebral cavernous malformation disease in a mouse model and uses contrast enhanced micro computed tomography to measure lesion burden. This method enhances the value of established mouse models to study the molecular basis and potential therapies for cerebral cavernous malformation and other cerebrovascular diseases.

Video: Induction and Micro-CT Imaging of Cerebral Cavernous Malformations in Mouse Model

Mouse Model of Middle Cerebral Artery Occlusion

Stroke is the most common fatal neurological disease in the United States 1. The majority of strokes (88%) result from blockage of blood vessels in the brain (ischemic stroke) 2. Since most ischemic strokes (~80%) occur in the territory of middle cerebral artery (MCA) 3, many animal stroke models that have been developed have focused on this artery. The intraluminal monofilament model of middle cerebral artery occlusion (MCAO) involves the insertion of a surgical filament into the external carotid artery and threading it forward into the internal carotid artery (ICA) until the tip occludes the origin of the MCA, resulting in a cessation of blood flow and subsequent brain infarction in the MCA territory 4. The technique can be used to model permanent or transient occlusion 5. If the suture is removed after a certain interval (30 min, 1 h, or 2 h), reperfusion is achieved (transient MCAO); if the filament is left in place (24 h) the procedure is suitable as a model of permanent MCAO. This technique does not require craniectomy, a neurosurgical procedure to remove a portion of skull, which may affect intracranial pressure and temperature 6. It has become the most frequently used method to mimic permanent and transient focal cerebral ischemia in rats and mice 7,8. To evaluate the extent of cerebral infarction, we stain brain slices with 2,3,5-triphenyltetrazolium chloride (TTC) to identify ischemic brain tissue 9. In this video, we demonstrate the MCAO method and the determination of infarct size by TTC staining.

We demonstrate in the video a method for producing a middle cerebral artery occlusion in adult mice using an intraluminal monofilament. We also show how to evaluate the extent of cerebral infarction by 2,3,5-triphenyltetrazolium chloride (TTC) staining.

Stroke is the most common fatal neurological disease in the United States 1. The majority of strokes (88%) result from blockage of blood vessels in the ...

Monitoring Tumor Metastases and Osteolytic Lesions with Bioluminescence and Micro CT Imaging

Following intracardiac delivery of MDA-MB-231-luc-D3H2LN cells to Nu/Nu mice, systemic metastases developed in the injected animals. Bioluminescence imaging using IVIS Spectrum was employed to monitor the distribution and development of the tumor cells following the delivery procedure including DLIT reconstruction to measure the tumor signal and its location.
Development of metastatic lesions to the bone tissues triggers osteolytic activity and lesions to tibia and femur were evaluated longitudinally using micro CT. Imaging was performed using a Quantum FX micro CT system with fast imaging and low X-ray dose. The low radiation dose allows multiple imaging sessions to be performed with a cumulative X-ray dosage far below LD50. A mouse imaging shuttle device was used to sequentially image the mice with both IVIS Spectrum and Quantum FX achieving accurate animal positioning in both the bioluminescence and CT images. The optical and CT data sets were co-registered in 3-dimentions using the Living Image 4.1 software. This multi-mode approach allows close monitoring of tumor growth and development simultaneously with osteolytic activity.

An experimental mouse model of bone metastasis was established following intracardiac delivery of luciferase expressing mammary tumor cells. Tumor development and resulted osteolytic lesion were monitored longitudinally with bioluminescence and micro CT imaging.

Following intracardiac delivery of MDA-MB-231-luc-D3H2LN cells to Nu/Nu mice, systemic metastases developed in the injected animals. Bioluminescence ...

Multi-photon Imaging of Tumor Cell Invasion in an Orthotopic Mouse Model of Oral Squamous Cell Carcinoma

Loco-regional invasion of head and neck cancer is linked to metastatic risk and presents a difficult challenge in designing and implementing patient management strategies. Orthotopic mouse models of oral cancer have been developed to facilitate the study of factors that impact invasion and serve as model system for evaluating anti-tumor therapeutics. In these systems, visualization of disseminated tumor cells within oral cavity tissues has typically been conducted by either conventional histology or with in vivo bioluminescent methods. A primary drawback of these techniques is the inherent inability to accurately visualize and quantify early tumor cell invasion arising from the primary site in three dimensions. Here we describe a protocol that combines an established model for squamous cell carcinoma of the tongue (SCOT) with two-photon imaging to allow multi-vectorial visualization of lingual tumor spread. The OSC-19 head and neck tumor cell line was stably engineered to express the F-actin binding peptide LifeAct fused to the mCherry fluorescent protein (LifeAct-mCherry). Fox1nu/nu mice injected with these cells reliably form tumors that allow the tongue to be visualized by ex-vivo application of two-photon microscopy. This technique allows for the orthotopic visualization of the tumor mass and locally invading cells in excised tongues without disruption of the regional tumor microenvironment. In addition, this system allows for the quantification of tumor cell invasion by calculating distances that invaded cells move from the primary tumor site. Overall this procedure provides an enhanced model system for analyzing factors that contribute to SCOT invasion and therapeutic treatments tailored to prevent local invasion and distant metastatic spread. This method also has the potential to be ultimately combined with other imaging modalities in an in vivo setting.

A comprehensive overview of the techniques involved in generating a mouse model of oral cancer and quantitative monitoring of tumor invasion within the tongue through multi-photon microscopy of labeled cells is presented. This system can serve as a useful platform for the molecular assessment and drug efficacy of anti-invasive compounds.

Loco-regional invasion of head and neck cancer is linked to metastatic risk and presents a difficult challenge in designing and implementing patient ...

The Application Of Permanent Middle Cerebral Artery Ligation in the Mouse

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

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

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

Non-invasive Optical Measurement of Cerebral Metabolism and Hemodynamics in Infants

Perinatal brain injury remains a significant cause of infant mortality and morbidity, but there is not yet an effective bedside tool that can accurately screen for brain injury, monitor injury evolution, or assess response to therapy. The energy used by neurons is derived largely from tissue oxidative metabolism, and neural hyperactivity and cell death are reflected by corresponding changes in cerebral oxygen metabolism (CMRO2). Thus, measures of CMRO2 are reflective of neuronal viability and provide critical diagnostic information, making CMRO2 an ideal target for bedside measurement of brain health.
Brain-imaging techniques such as positron emission tomography (PET) and single-photon emission computed tomography (SPECT) yield measures of cerebral glucose and oxygen metabolism, but these techniques require the administration of radionucleotides, so they are used in only the most acute cases.
Continuous-wave near-infrared spectroscopy (CWNIRS) provides non-invasive and non-ionizing radiation measures of hemoglobin oxygen saturation (SO2) as a surrogate for cerebral oxygen consumption. However, SO2 is less than ideal as a surrogate for cerebral oxygen metabolism as it is influenced by both oxygen delivery and consumption. Furthermore, measurements of SO2 are not sensitive enough to detect brain injury hours after the insult 1,2, because oxygen consumption and delivery reach equilibrium after acute transients 3. We investigated the possibility of using more sophisticated NIRS optical methods to quantify cerebral oxygen metabolism at the bedside in healthy and brain-injured newborns. More specifically, we combined the frequency-domain NIRS (FDNIRS) measure of SO2 with the diffuse correlation spectroscopy (DCS) measure of blood flow index (CBFi) to yield an index of CMRO2 (CMRO2i) 4,5.
With the combined FDNIRS/DCS system we are able to quantify cerebral metabolism and hemodynamics. This represents an improvement over CWNIRS for detecting brain health, brain development, and response to therapy in neonates. Moreover, this method adheres to all neonatal intensive care unit (NICU) policies on infection control and institutional policies on laser safety. Future work will seek to integrate the two instruments to reduce acquisition time at the bedside and to implement real-time feedback on data quality to reduce the rate of data rejection.

We combined frequency-domain near-infrared spectroscopy measures of cerebral hemoglobin oxygenation with diffuse correlation spectroscopy measures of cerebral blood flow index to estimate an index of oxygen metabolism. We tested the utility of this measure as a bedside screening tool to evaluate the health and development of the newborn brain.

Perinatal brain injury remains a significant cause of infant mortality  and morbidity, but there is not yet an effective bedside tool that can  accurately ...

Pharmacologic Induction of Epidermal Melanin and Protection Against Sunburn in a Humanized Mouse Model

Fairness of skin, UV sensitivity and skin cancer risk all correlate with the physiologic function of the melanocortin 1 receptor, a Gs-coupled signaling protein found on the surface of melanocytes. Mc1r stimulates adenylyl cyclase and cAMP production which, in turn, up-regulates melanocytic production of melanin in the skin. In order to study the mechanisms by which Mc1r signaling protects the skin against UV injury, this study relies on a mouse model with "humanized skin" based on epidermal expression of stem cell factor (Scf). K14-Scf transgenic mice retain melanocytes in the epidermis and therefore have the ability to deposit melanin in the epidermis. In this animal model, wild type Mc1r status results in robust deposition of black eumelanin pigment and a UV-protected phenotype. In contrast, K14-Scf animals with defective Mc1r signaling ability exhibit a red/blonde pigmentation, very little eumelanin in the skin and a UV-sensitive phenotype. Reasoning that eumelanin deposition might be enhanced by topical agents that mimic Mc1r signaling, we found that direct application of forskolin extract to the skin of Mc1r-defective fair-skinned mice resulted in robust eumelanin induction and UV protection 1. Here we describe the method for preparing and applying a forskolin-containing natural root extract to K14-Scf fair-skinned mice and report a method for measuring UV sensitivity by determining minimal erythematous dose (MED). Using this animal model, it is possible to study how epidermal cAMP induction and melanization of the skin affect physiologic responses to UV exposure.

Epidermal melanin is induced by topical application of forskolin in a murine model of the fair-skinned UV-sensitive human. Pharmacologic manipulation of cAMP levels in the skin and epidermal darkening strongly protect against UV-mediated inflammation (sunburn) as measured by the minimum erythematous dose (MED) assay.

Fairness of skin, UV sensitivity and skin cancer  risk all correlate with the physiologic function of the melanocortin 1  receptor, a Gs-coupled signaling ...

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 ...

A Battery of Motor Tests in a Neonatal Mouse Model of Cerebral Palsy

As the sheer number of transgenic mice strains grow and rodent models of pediatric disease increase, there is an expanding need for a comprehensive, standardized battery of neonatal mouse motor tests. These tests can validate injury or disease models, determine treatment efficacy and/or assess motor behaviors in new transgenic strains. This paper presents a series of neonatal motor tests to evaluate general motor function, including ambulation, hindlimb foot angle, surface righting, negative geotaxis, front- and hindlimb suspension, grasping reflex, four limb grip strength and cliff aversion. Mice between the ages of post-natal day 2 to 14 can be used. In addition, these tests can be used for a wide range of neurological and neuromuscular pathologies, including cerebral palsy, hypoxic-ischemic encephalopathy, traumatic brain injury, spinal cord injury, neurodegenerative diseases, and neuromuscular disorders. These tests can also be used to determine the effects of pharmacological agents, as well as other types of therapeutic interventions. In this paper, motor deficits were evaluated in a novel neonatal mouse model of cerebral palsy that combines hypoxia, ischemia and inflammation. Forty-eight hours after injury, five tests out of the nine showed significant motor deficits: ambulation, hindlimb angle, hindlimb suspension, four limb grip strength, and grasping reflex. These tests revealed weakness in the hindlimbs, as well as fine motor skills such as grasping, which are similar to the motor deficits seen in human cerebral palsy patients.

Presented is a concise battery of mouse neonatal motor tests. Using these tests, neonatal motor deficits can be demonstrated in a variety of neonatal motor disorders. By having a standardized set of tests, results from different studies can be compared, allowing for better and accurate reporting between groups.

As the sheer number of transgenic mice strains grow and rodent models of pediatric disease increase, there is an expanding need for a comprehensive, ...

In Vivo Tracking of Edema Development and Microvascular Pathology in a Model of Experimental Cerebral Malaria Using Magnetic Resonance Imaging

Cerebral malaria is a sign of severe malarial disease and is often a harbinger of death. While aggressive management can be life-saving, the detection of cerebral malaria can be difficult. We present an experimental mouse model of cerebral malaria that shares multiple features of the human disease, including edema and microvascular pathology. Using magnetic resonance imaging (MRI), we can detect and track the blood-brain barrier disruption, edema development, and subsequent brain swelling. We describe multiple MRI techniques that can visualize these pertinent pathological changes. Thus, we show that MRI represents a valuable tool to visualize and track pathological changes, such as edema, brain swelling, and microvascular pathology, in vivo.

In Vivo Tracking of Edema Development and Microvascular Pathology in a Model of Experimental Cerebral Malaria Using Magnetic Resonance Imaging

We describe a mouse model of experimental cerebral malaria and show how inflammatory and microvascular pathology can be tracked in vivo using magnetic resonance imaging.

Cerebral malaria is a sign of severe malarial disease and is often a harbinger of death. While aggressive management can be life-saving, the detection of ...

Quantitative Micro-CT Analysis of Aortopathy in a Mouse Model of &#946;-aminopropionitrile-induced Aortic Aneurysm and Dissection

Aortic aneurysm and dissection is associated with significant morbidity and mortality in the population and can be highly lethal. While animal models of aortic disease exist, in vivo imaging of the vasculature has been limited. In recent years, micro-computerized tomography (micro-CT) has emerged as a preferred modality for imaging both large and small vessels both in vivo and ex vivo. In conjunction with a method of vascular casting, we have successfully used micro-CT to characterize the frequency and distribution of aortic pathology in &#946;-aminopropionitrile-treated C57/Bl6 mice. Technical limitations of this method include variations in the quality of the perfusion introduced by poor animal preparation, the application of proper methodologies for vessel size quantification, and the non-survivability of this procedure. This article details a methodology for the intravascular perfusion of a lead-based radiopaque silicone rubber for the quantitative characterization of aortopathy in a mouse model of aneurysm and dissection. In addition to visualizing aortic pathology, this method may be used for examining other vascular beds in vivo or vascular beds removed post-mortem.

This article describes a detailed methodology of using a radiopaque lead-based silicone rubber to perfuse the murine vasculature for aortic diameter quantification in a mouse model of aortic aneurysm and dissection.

Aortic aneurysm and dissection is associated with significant morbidity and mortality in the population and can be highly lethal. While animal models of ...