Name: longitudinal in vivo imaging of the cerebrovasculature: relevance to cns diseases
Uploaded: 2016-12-06T14:00:00
Description: Watch this Scientific Journal Video about Longitudinal In Vivo Imaging of the Cerebrovasculature: Relevance to CNS Diseases at JoVE.com

The authors would like to acknowledge the Ligue Francaise contre l&#39;&#233;pilepsie (to M.A-L), Institut National de la Sant&#233; et de la Recherche M&#233;dicale Grant AVENIR R12087FS (to F.J), grant from the university of Montpellier (to F.J) and grant from Federation pour la Recherche sur le Cerveau (to N.M). We acknowledge the technical assistance of Chrystel Lafont at the IPAM in vivo imaging core platform facility of Montpellier. We also thank Mary Vernov (Weill Cornell Medical College) for proofreading the manuscript.

Mice are allowed ad libitum access to food, water, and maintained on a 12-hr light-dark cycle. All procedures involving laboratory animals conformed to National and European laws and were approved by the French Ministry for Education and Scientific Research (CEEA-LR-00651-01). A total of 6 transgenic 5xFAD and 4 littermate wildtype (WT) control mice were used for this procedure.
1. Pre-operative Preparation
<ol>
	<li>Intraperitoneally (IP) inject Methoxy-X04 (10 mg/kg) 48 hr before surgery to label A&#9...

<ol>
	<li>Harb, R., Whiteus, C., Freitas, C., Grutzendler, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vivo+imaging+of+cerebral+microvascular+plasticity+from+birth+to+death.">In vivo imaging of cerebral microvascular plasticity from birth to death.</a> J Cereb Blood Flow Metab. 33 (1), 146-156 (2013).</li><li>Whiteus, C., Freitas, C., Grutzendler, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Perturbed+neural+activity+disrupts+cerebral+angiogenesis+during+a+postnatal+critical+period.">Perturbed neural activity disrupts cerebral angiogenesis during a postnatal critical period.</a> Nature. 505 (7483), 407-411 (2014).</li><li>Masamoto, K., 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=Microvascular+sprouting,+extension,+and+creation+of+new+capillary+connections+with+adaptation+of+the+neighboring+astrocytes+in+adult+mouse+cortex+under+chronic+hypoxia.">Microvascular sprouting, extension, and creation of new capillary connections with adaptation of the neighboring astrocytes in adult mouse cortex under chronic hypoxia.</a> J Cereb Blood Flow Metab. 34 (2), 325-331 (2014).</li><li>Marchi, N., Lerner-Natoli, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cerebrovascular+remodeling+and+epilepsy.">Cerebrovascular remodeling and epilepsy.</a> Neuroscientist. 19 (3), 304-312 (2013).</li><li>Giannoni, 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=Cerebrovascular+pathology+during+the+progression+of+experimental+Alzheimer's+disease.">Cerebrovascular pathology during the progression of experimental Alzheimer's disease.</a> Neurobiol Dis. 88, 107-117 (2016).</li><li>Kimbrough, I. F., Robel, S., Roberson, E. D., Sontheimer, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vascular+amyloidosis+impairs+the+gliovascular+unit+in+a+mouse+model+of+Alzheimer's+disease.">Vascular amyloidosis impairs the gliovascular unit in a mouse model of Alzheimer's disease.</a> Brain. 138 (Pt 12), 3716-3733 (2015).</li><li>Herzig, M. 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=Abeta+is+targeted+to+the+vasculature+in+a+mouse+model+of+hereditary+cerebral+hemorrhage+with+amyloidosis.">Abeta is targeted to the vasculature in a mouse model of hereditary cerebral hemorrhage with amyloidosis.</a> Nat Neurosci. 7 (9), 954-960 (2004).</li><li>Oakley, H., 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=Intraneuronal+beta-amyloid+aggregates,+neurodegeneration,+and+neuron+loss+in+transgenic+mice+with+five+familial+Alzheimer's+disease+mutations:+potential+factors+in+amyloid+plaque+formation.">Intraneuronal beta-amyloid aggregates, neurodegeneration, and neuron loss in transgenic mice with five familial Alzheimer's disease mutations: potential factors in amyloid plaque formation.</a> J Neurosci. 26 (40), 10129-10140 (2006).</li><li>Liston, 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=Circadian+glucocorticoid+oscillations+promote+learning-dependent+synapse+formation+and+maintenance.">Circadian glucocorticoid oscillations promote learning-dependent synapse formation and maintenance.</a> Nat Neurosci. 16 (6), 698-705 (2013).</li><li>Yang, G., Pan, F., Parkhurst, C. N., Grutzendler, J., Gan, W. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thinned-skull+cranial+window+technique+for+long-term+imaging+of+the+cortex+in+live+mice.">Thinned-skull cranial window technique for long-term imaging of the cortex in live mice.</a> Nat Protoc. 5 (2), 201-208 (2010).</li><li>Klunk, W. E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Imaging+Abeta+plaques+in+living+transgenic+mice+with+multiphoton+microscopy+and+methoxy-X04,+a+systemically+administered+Congo+red+derivative.">Imaging Abeta plaques in living transgenic mice with multiphoton microscopy and methoxy-X04, a systemically administered Congo red derivative.</a> J Neuropathol Exp Neurol. 61 (9), 797-805 (2002).</li><li>Yardeni, T., Eckhaus, M., Morris, H. 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(43), (2010).</li><li>Joseph-Mathurin, N., 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=Amyloid+beta+immunization+worsens+iron+deposits+in+the+choroid+plexus+and+cerebral+microbleeds.">Amyloid beta immunization worsens iron deposits in the choroid plexus and cerebral microbleeds.</a> Neurobiol Aging. 34 (11), 2613-2622 (2013).</li><li>Sadowski, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Targeting+prion+amyloid+deposits+in+vivo.">Targeting prion amyloid deposits in vivo.</a> J Neuropathol Exp Neurol. 63 (7), 775-784 (2004).</li></ol>

The open-skull technique for in vivo two-photon microscopy offers the advantage of unlimited imaging sessions of large imaging fields13,14. However, this technique also produces inflammation in the region of interest14, often incompatible or impacting neuro-vascular read-outs15. On the contrary, the thinned skull transcranial technique does not result in neuro-inflammation, enabling reliable imaging of the cerebrovascular structures and plaque accumulation10,14. A seco...

The brain vasculature is a multi-cellular structure, which is anatomically and functionally coupled to neurons. A dynamic remodeling of vessels occurs throughout brain development and during the progression of pathologies of the central nervous system (CNS) 1,2. It is widely accepted that cerebrovascular damage is a hallmark of several CNS diseases, including epilepsy, Alzheimer&#39;s disease (AD), traumatic brain injury and encephalitis 3,4. Therefore, tracking cerebrovascular changes in vivo becomes significant when modeling CNS diseases, from onset and into chronic phases. As cerebrovascular modifications often occur concomitantly with neuronal damage or plasticity, imaging of the neuro-vasculature represents a key entry point to decipher CNS disease pathophysiology.
This protocol describes a longitudinal two-photon based procedure to track the remodeling of the cerebrovasculature in a mouse model of AD, a progressive pathology marked by cerebrovascular defects on large and small caliber vessels due to amyloidogenic plaque deposition 5-7. This procedure allows for the visualization of amyloid deposits and tracking of their position and growth with respect to neurovascular remodeling throughout the course of the disease. Vital fluorescent dyes are injected before each imaging session for the visualization of the cerebrovasculature and amyloid plaques in transgenic AD mice8. Repeated imaging sessions of a ROI through a thinned skull transcranial window is non-invasive and the method of choice to assess neurovascular remodeling in the living mouse brain 2,5,9,10.
The procedure below outlines the surgical protocol, image acquisition and processing. The early progression of cerebral amyloid angiopathy (CAA) mostly at large leptomeningeal and penetrating arterioles is characterized.

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			<td height="21" style="height:21px;width:216px;">methoxy-X04</td>
			<td style="width:125px;">tocris</td>
			<td align="right" style="width:119px;">4920</td>
			<td style="width:167px;">use 10 mg/Kg</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">FITC-Dextran 70Kda</td>
			<td style="width:125px;">sigma</td>
			<td align="right" style="width:119px;">46945</td>
			<td>use 100 mg/Kg</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">gelfoam/Bloxang</td>
			<td style="width:125px;">Bausch and Lomb</td>
			<td style="width:119px;"></td>
			<td></td>
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			<td height="21" style="height:21px;width:216px;">micorsurgical blade</td>
			<td style="width:125px;">surgistar</td>
			<td align="right" style="width:119px;">6900</td>
			<td>must be sharp and not dented</td>
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			<td height="21" style="height:21px;width:216px;">povidone-iodine</td>
			<td style="width:125px;">betadine</td>
			<td style="width:119px;"></td>
			<td>antisceptic solution</td>
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			<td height="21" style="height:21px;width:216px;">binocular stereomicroscope</td>
			<td style="width:125px;">olympus</td>
			<td style="width:119px;">SX10</td>
			<td>optimal image contrast is crucial for this procedure</td>
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			<td height="21" style="height:21px;width:216px;">2-photon microscope</td>
			<td style="width:125px;">zeiss</td>
			<td style="width:119px;"></td>
			<td>Zeiss LSM 710mp</td>
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			<td height="21" style="height:21px;width:216px;">fine scissors-toughcut</td>
			<td style="width:125px;">Fine science tools</td>
			<td>14058-09</td>
			<td>this scissors are optimized for cutting skin and soft tissue</td>
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longitudinal in vivo imaging of the cerebrovasculature: relevance to cns diseases

Remodeling of the brain vasculature is a common trait of brain pathologies. In vivo imaging techniques are fundamental to detect cerebrovascular plasticity or damage occurring overtime and in relation to neuronal activity or blood flow. In vivo two-photon microscopy allows the study of the structural and functional plasticity of large cellular units in the living brain. In particular, the thinned-skull window preparation allows the visualization of cortical regions of interest (ROI) without inducing significant brain inflammation. Repetitive imaging sessions of cortical ROI are feasible, providing the characterization of disease hallmarks over time during the progression of numerous CNS diseases. This technique accessing the pial structures within 250 &#956;m of the brain relies on the detection of fluorescent probes encoded by genetic cellular markers and/or vital dyes. The latter (e.g., fluorescent dextrans) are used to map the luminal compartment of cerebrovascular structures. Germane to the protocol described herein is the use of an in vivo marker of amyloid deposits, Methoxy-O4, to assess Alzheimer&#39;s disease (AD) progression. We also describe the post-acquisition image processing used to track vascular changes and amyloid depositions. While focusing presently on a model of AD, the described protocol is relevant to other CNS disorders where pathological cerebrovascular changes occur.

This protocol describes a method for visualizing the cerebrovasculature and amyloid deposits overtime. Fluorescent dyes were injected to label amyloid depositions (methoxy-XO4) 11 and to fill the cerebrovascular lumen (FITC-Dextran)1. 3D image analysis software modules were used to create 3D images of a constant field of view captured at consecutive time points. Representative images obtained in the somatosensory cortex of 5XFAD mice5 (genetic model of AD)...

Watch this Scientific Journal Video about Longitudinal In Vivo Imaging of the Cerebrovasculature: Relevance to CNS Diseases at JoVE.com

Longitudinal In Vivo Imaging of the Cerebrovasculature: Relevance to CNS Diseases

This manuscript describes a procedure to track the remodeling of the cerebrovasculature during amyloid plaque accumulation in vivo using longitudinal two-photon microscopy. A thinned-skull preparation enables the visualization of fluorescent dyes to assess the progression of cerebrovascular damage in a mouse model of Alzheimer&#39;s disease.

Longitudinal In Vivo Imaging of the Cerebrovasculature: Relevance to CNS Diseases

Remodeling of the brain vasculature is a common trait of brain pathologies. In vivo imaging techniques are fundamental to detect cerebrovascular ...

The overall goal of this procedure is to track the remodeling of the vasculature in the mouse brain during the progression of a chronic disease over extended periods of time. This method can help answer key questions in the field of neuroscience, such as the role of cerebral vasculature remodeling in diseases of the central nervous system. The main advantage of this technique is that it is minimally invasive and without neural inflammation, making it ideal to study pathologies where inflammation is actually implicated.This technique allows the visualization of pial and and penetrating cortical vessels, complementing histological techniques direct at the visualization of microcapillaries in the parenchymal of the blood-brain barrier. Demonstrating the procedure will be Margarita Arango-Lievano. She's a post-doc from my laboratory.To begin this procedure, clean the surgical bench and microscope plate with 70%ethanol and cover them with a clean, absorbent cloth. Next, check the appropriate level of anesthesia with paw or tail pinches. Then apply sterile ophthalmic ointment to the eyes and shave the fur from the nose to the ears with a razor blade.Afterward, sterilize the skin with povidone iodine antiseptic solution. Place the mouse under the binocular microscope and make a skin incision from the ears to the nose. Pull the skin sideways to expose the skull.Then tear the periosteum and repeatedly rinse the skull with sterile ACSF to stop possible bleeding. In this procedure, remove the eye ointment with a cotton tip. Then apply a drop of topical ophthalmic anesthetic.Gently pressure the skin around the eye socket to achieve protrusion. After that, inject FITC conjugated with dextran in the retro-orbital sinus. Subsequently, apply sterile ophthalmic ointment to the eyes.Ensure that the skin is retracted and the skull is clean and dry around the selected imaging area. Then apply a small amount of cyanoacrylic glue around the window of the head mount device and glue the head mount device around the target region. Subsequently, apply gentle pressure to the head mount for several seconds.Pull the ends of the skin to the edge of the window of the head mount device, making sure the area is dry. Secure the skin and the edge of the window with a small amount of cyanoacrylic glue and wait until dry. Afterward, secure the animal at the stage using the head mount device.Rinse the bone in the target area with sterile ACSF and ensure that the well between the skin and the head mount device is perfectly sealed. Following that, wrap the mouse in a survival blanket to maintain normothermia. Now perform thinning of the skull in ACSF solution to attenuate vibrations created by drilling.And keep in mind to change the ACSF regularly to clear the bone debris and to avoid tissue overheating. Using a dental drill, start thinning the skull surface in an area with the diameter of one millimeter using regular vertical motion parallel to the skull, and remove most of the spongy bone. Note that the bone near the sutures is highly vascularized.If bleeding occurs, apply ACSF pre-soaked gel foam to stop it. So we keep the bone to limit inflammation, but excessive pressure or heating during the thinning procedure can also result in inflammation. Use a sharp, disposable, ophthalmic microsurgical blade to continue with the thinning of the skull to result in a final region of about 0.5 millimeters in diameter with a thickness of 20 to 35 micrometers, being careful not apply excessive pressure.Due to bone regrowth and scarring, it is necessary to further thin the window at each imaging session. In this step, transfer the mouse with the head mount stage under the two-photon laser microscope. Using a 20X water immersion objective with a numerical aperture of 1.0, locate the thin cranial window at the center of the optical field using the epifluorescent lamp.Ensure that the objective is always immersed in ACSF. Next, start laser scanning with a mode-locked pulse laser. Set the excitation wavelength at 750 nanometers to detect the emitted fluorescence of the methoxy-X04 in the blue channel and FITC-dextran in the green channel.Acquire a low magnification stack at 0.7X numerical zoom in order to create a 3D map for the precise re-localization of the ROI at later time points. Then acquire a mosaic of four high-digital magnification images with a two X numerical zoom. Using the imaging software, move the window in 200-micrometer steps to capture all regions.The depth of the stacks is typically 250 micrometers starting from the pial surface in each image of the mosaic. Before removing the mouse from the microscope, take a picture or make a hand-drawn 2D map of the pial vasculature for future re-localization of the imaging field. Shown here is the comparison of two reconstructed images of the microvasculature and amyloid depositions on a five X FAD mouse at four and five months of age.Amyloid plaques are indicated with white asterisks, and new plaques appearing at five months are indicated by yellow asterisks. A rare instance of plaque reduction is indicated with an orange asterisk. Newly formed microvessels are indicated with yellow arrows, while vascular occlusion is indicated with a red arrow.This figure shows that the amyloid vascular deposits on large-caliber vessels. At the same time, amyloid plaques can be also observed on small-caliber vessels. Red arrows indicate occluded vessels, whereas white asterisks indicate growing amyloid plaques.So once mastered, this technique can be performed in 1 1/2 hours, including the surgery and imaging steps. While attempting this procedure, it is important to plan the number of imaging session in order to limit excessive thinning in the first session. Overall, these procedures allow tracking changes in cerebral vasculature during disease progression.

longitudinal-vivo-imaging-cerebrovasculature-relevance-to-cns

Research

JoVE Journal

Medicine

The Use of Pharmacological-challenge fMRI in Pre-clinical Research: Application to the 5-HT System

Pharmacological MRI (phMRI) is a new and promising method to study the effects of substances on brain function that can ultimately be used to unravel underlying neurobiological mechanisms behind drug action and neurotransmitter-related disorders, such as depression and ADHD. Like most of the imaging methods (PET, SPECT, CT) it represents a progress in the investigation of brain disorders and the related function of neurotransmitter pathways in a non-invasive way with respect of the overall neuronal connectivity. Moreover it also provides the ideal tool for translation to clinical investigations. MRI, while still behind in molecular imaging strategies compared to PET and SPECT, has the great advantage to have a high spatial resolution and no need for the injection of a contrast-agent or radio-labeled molecules, thereby avoiding the repetitive exposure to ionizing radiations. Functional MRI (fMRI) is extensively used in research and clinical setting, where it is generally combined with a psycho-motor task. phMRI is an adaptation of fMRI enabling the investigation of a specific neurotransmitter system, such as serotonin (5-HT), under physiological or pathological conditions following activation via administration of a specific challenging drug.
The aim of the method described here is to assess brain 5-HT function in free-breathing animals. By challenging the 5-HT system while simultaneously acquiring functional MR images over time, the response of the brain to this challenge can be visualized. Several studies in animals have already demonstrated that drug-induced increases in extracellular levels of e.g. 5-HT (releasing agents, selective re-uptake blockers, etc) evoke region-specific changes in blood oxygenation level dependent (BOLD) MRI signals (signal due to a change of the oxygenated/deoxygenated hemoglobin levels occurring during brain activation through an increase of the blood supply to supply the oxygen and glucose to the demanding neurons) providing an index of neurotransmitter function. It has also been shown that these effects can be reversed by treatments that decrease 5-HT availability16,13,18,7. In adult rats, BOLD signal changes following acute SSRI administration have been described in several 5-HT related brain regions, i.e. cortical areas, hippocampus, hypothalamus and thalamus9,16,15. Stimulation of the 5-HT system and its response to this challenge can be thus used as a measure of its function in both animals and humans2,11.

The goal of this technique is to assess serotonin (5-HT) neurotransmitter function in the live and free-breathing animal with pharmacological magnetic resonance imaging (phMRI) and an intravenous challenge with a selective serotonin reuptake inhibitor (SSRI), fluoxetine.

Pharmacological MRI (phMRI) is a new and promising method to study the effects of substances on brain function that can ultimately be used to unravel ...

Intranasal Administration of CNS Therapeutics to Awake Mice

Intranasal administration is a method of delivering therapeutic agents to the central nervous system (CNS). It is non-invasive and allows large molecules that do not cross the blood-brain barrier access to the CNS. Drugs are directly targeted to the CNS with intranasal delivery, reducing systemic exposure and thus unwanted systemic side effects1. Delivery from the nose to the CNS occurs within minutes along both the olfactory and trigeminal neural pathways via an extracellular route and does not require drug to bind to any receptor or axonal transport2. Intranasal delivery is a widely publicized method and is currently being used in human clinical trials3.
Intranasal delivery of drugs in animal models allows for initial evaluation of pharmacokinetic distribution and efficacy. With mice, it is possible to administer drugs to awake (non-anesthetized) animals on a regular basis using a specialized intranasal grip. Awake delivery is beneficial because it allows for long-term chronic dosing without anesthesia, it takes less time than with anesthesia, and can be learned and done by many people so that teams of technicians can dose large numbers of mice in short periods. Efficacy of therapeutics administered intranasally in this way to mice has been demonstrated in a number of studies including insulin in diabetic mouse models 4-6 and deferoxamine in Alzheimer's mouse models. 7,8
The intranasal grip for mice can be learned, but is not easy and requires practice, skill, and a precise grip to effectively deliver drug to the brain and avoid drainage to the lung and stomach. Mice are restrained by hand using a modified scruff in the non-dominant hand with the neck held parallel to the floor, while drug is delivered with a pipettor using the dominant hand. It usually takes 3-4 weeks of acclimating to handling before mice can be held with this grip without a stress response. We have prepared this JoVE video to make this intranasal delivery technique more accessible.

A method to intranasally administer drugs to awake mice for the purpose of targeting the brain is described. This method allows for repeat dosing over long periods using intranasal administration of drug without anesthesia, and nose-to-brain delivery with minimal systemic exposure.

Intranasal administration is a method of delivering  therapeutic agents to the central nervous system (CNS). It is  non-invasive and allows large ...

In vivo Macrophage Imaging Using MR Targeted Contrast Agent for Longitudinal Evaluation of Septic Arthritis

Macrophages are key-cells in the initiation, the development and the regulation of the inflammatory response to bacterial infection. Macrophages are intensively and increasingly recruited in septic joints from the early phases of infection and the infiltration is supposed to regress once efficient removal of the pathogens is obtained. The ability to identify in vivo macrophage activity in an infected joint can therefore provide two main applications: early detection of acute synovitis and monitoring of therapy.
In vivo noninvasive detection of macrophages can be performed with magnetic resonance imaging using iron nanoparticles such as ultrasmall superparamagnetic iron oxide (USPIO). After intravascular or intraarticular administration, USPIO are specifically phagocytized by activated macrophages, and, due to their magnetic properties, induce signal changes in tissues presenting macrophage infiltration. A quantitative evaluation of the infiltrate is feasible, as the area with signal loss (number of dark pixels) observed on gradient echo MR images after particles injection is correlated with the amount of iron within the tissue and therefore reflects the number of USPIO-loaded cells.
We present here a protocol to perform macrophage imaging using USPIO-enhanced MR imaging in an animal model of septic arthritis, allowing an initial and longitudinal in vivo noninvasive evaluation of macrophages infiltration and an assessment of therapy action.

In vivo Macrophage Imaging Using MR Targeted Contrast Agent for Longitudinal Evaluation of Septic Arthritis

We demonstrate how to perform macrophage MR imaging using ultrasmall superparamagnetic contrast agent (USPIO) in septic arthritis, allowing an initial and longitudinal in vivo non-invasive evaluation of macrophages infiltration and an assessment of therapy efficacy.

Macrophages are key-cells in the initiation, the development and the regulation of the inflammatory response to bacterial infection. Macrophages are ...

Diffusion Tensor Magnetic Resonance Imaging in the Analysis of Neurodegenerative Diseases

Diffusion tensor imaging (DTI) techniques provide information on the microstructural processes of the cerebral white matter (WM) in vivo. The present applications are designed to investigate differences of WM involvement patterns in different brain diseases, especially neurodegenerative disorders, by use of different DTI analyses in comparison with matched controls. 	
DTI data analysis is performed in a variate fashion, i.e. voxelwise comparison of regional diffusion direction-based metrics such as fractional anisotropy (FA), together with fiber tracking (FT) accompanied by tractwise fractional anisotropy statistics (TFAS) at the group level in order to identify differences in FA along WM structures, aiming at the definition of regional patterns of WM alterations at the group level. Transformation into a stereotaxic standard space is a prerequisite for group studies and requires thorough data processing to preserve directional inter-dependencies. The present applications show optimized technical approaches for this preservation of quantitative and directional information during spatial normalization in data analyses at the group level. On this basis, FT techniques can be applied to group averaged data in order to quantify metrics information as defined by FT. Additionally, application of DTI methods, i.e. differences in FA-maps after stereotaxic alignment, in a longitudinal analysis at an individual subject basis reveal information about the progression of neurological disorders. Further quality improvement of DTI based results can be obtained during preprocessing by application of a controlled elimination of gradient directions with high noise levels.	
In summary, DTI is used to define a distinct WM pathoanatomy of different brain diseases by the combination of whole brain-based and tract-based DTI analysis.

Diffusion tensor imaging (DTI) basically serves as an MRI-based tool to identify in vivo the microstructure of the brain and pathological processes due to neurological disorders within the cerebral white matter. DTI-based analyses allow for application to brain diseases both at the group level and in single subject data.

Diffusion tensor imaging (DTI) techniques provide information on the microstructural processes of the cerebral white matter (WM) in vivo. The present ...

Transplantation into the Anterior Chamber of the Eye for Longitudinal, Non-invasive In vivo Imaging with Single-cell Resolution in Real-time

Intravital imaging has emerged as an indispensable tool in biological research. In the process, many imaging techniques have been developed to study different biological processes in animals non-invasively. However, a major technical limitation in existing intravital imaging modalities is the inability to combine non-invasive, longitudinal imaging with single-cell resolution capabilities. We show here how transplantation into the anterior chamber of the eye circumvents such significant limitation offering a versatile experimental platform that enables non-invasive, longitudinal imaging with cellular resolution in vivo. We demonstrate the transplantation procedure in the mouse and provide representative results using a model with clinical relevance, namely pancreatic islet transplantation. In addition to enabling direct visualization in a variety of tissues transplanted into the anterior chamber of the eye, this approach provides a platform to screen drugs by performing long-term follow up and monitoring in target tissues. Because of its versatility, tissue/cell transplantation into the anterior chamber of the eye not only benefits transplantation therapies, it extends to other in vivo applications to study physiological and pathophysiological processes such as signal transduction and cancer or autoimmune disease development.

Transplantation into the Anterior Chamber of the Eye for Longitudinal, Non-invasive In vivo Imaging with Single-cell Resolution in Real-time

A new approach combining intraocular transplantation and confocal microscopy enables longitudinal, non-invasive real-time imaging with single-cell resolution within grafted tissues in vivo. We demonstrate how to transplant pancreatic islets into the anterior chamber of the mouse eye.

Intravital imaging has emerged as an indispensable tool in biological research.  In the process, many imaging techniques have been developed to study ...

In vivo 19F MRI for Cell Tracking

In vivo 19F MRI allows quantitative cell tracking without the use of ionizing radiation. It is a noninvasive technique that can be applied to humans. Here, we describe a general protocol for cell labeling, imaging, and image processing. The technique is applicable to various cell types and animal models, although here we focus on a typical mouse model for tracking murine immune cells. The most important issues for cell labeling are described, as these are relevant to all models. Similarly, key imaging parameters are listed, although the details will vary depending on the MRI system and the individual setup. Finally, we include an image processing protocol for quantification. Variations for this, and other parts of the protocol, are assessed in the Discussion section. Based on the detailed procedure described here, the user will need to adapt the protocol for each specific cell type, cell label, animal model, and imaging setup. Note that the protocol can also be adapted for human use, as long as clinical restrictions are met.

In vivo 19F MRI for Cell Tracking

We describe a general protocol for in vivo cell tracking using MRI in a mouse model with ex vivo labeled cells. A typical protocol for cell labeling, image acquisition processing and quantification is included.

In vivo 19F MRI allows quantitative cell tracking without the use of ionizing radiation. It is a noninvasive technique that can be applied to humans. ...

Pulse Wave Velocity Testing in the Baltimore Longitudinal Study of Aging

Carotid-femoral pulse wave velocity is considered the gold standard for measurements of central arterial stiffness obtained through noninvasive methods1.&#160;Subjects are placed in the supine position and allowed to rest quietly for at least 10 min prior to the start of the exam. The proper cuff size is selected and a blood pressure is obtained using an oscillometric device. Once a resting blood pressure has been obtained, pressure waveforms are acquired from the right femoral and right common carotid arteries. The system then automatically calculates the pulse transit time between these two sites (using the carotid artery as a surrogate for the descending aorta). Body surface measurements are used to determine the distance traveled by the pulse wave between the two sampling sites. This distance is then divided by the pulse transit time resulting in the pulse wave velocity. The measurements are performed in triplicate and the average is used for analysis.

Pulse wave velocity (PWV) measurement assesses arterial stiffness by a tonometry-based system that measures the speed with which arterial pressure wave travels along the arterial tree, typically approximating the time that it takes this wave to travel from the descending aorta (using the carotid artery as a surrogate) to the femoral artery. Carotid-femoral PWV increases two- to threefold across the adult lifespan.

Carotid-femoral pulse wave velocity is considered the gold standard for measurements of central arterial stiffness obtained through noninvasive ...

Acute Brain Trauma in Mice Followed By Longitudinal Two-photon Imaging

Although acute brain trauma often results from head damage in different accidents and affects a substantial fraction of the population, there is no effective treatment for it yet. Limitations of currently used animal models impede understanding of the pathology mechanism. Multiphoton microscopy allows studying cells and tissues within intact animal brains longitudinally under physiological and pathological conditions. Here, we describe two models of acute brain injury studied by means of two-photon imaging of brain cell behavior under posttraumatic conditions. A selected brain region is injured with a sharp needle to produce a trauma of a controlled width and depth in the brain parenchyma. Our method uses stereotaxic prick with a syringe needle, which can be combined with simultaneous drug application. We propose that this method can be used as an advanced tool to study cellular mechanisms of pathophysiological consequences of acute trauma in mammalian brain in vivo. In this video, we combine acute brain injury with two preparations: cranial window and skull thinning. We also discuss advantages and limitations of both preparations for multisession imaging of brain regeneration after trauma.

Acute brain trauma is a severe injury that has no adequate treatment to date. Multiphoton microscopy allows studying longitudinally the process of acute brain trauma development and probing therapeutical strategies in rodents. Two models of acute brain trauma studied with in vivo two-photon imaging of brain are demonstrated in this protocol.

Although acute brain trauma often results from head damage in different accidents and affects a substantial fraction of the population, there is no ...

Rose Bengal Photothrombosis by Confocal Optical Imaging In Vivo: A Model of Single Vessel Stroke

In vivo imaging techniques have increased in utilization due to recent advances in imaging dyes and optical technologies, allowing for the ability to image cellular events in an intact animal. Additionally, the ability to induce physiological disease states such as stroke in vivo increases its utility. The technique described herein allows for physiological assessment of cellular responses within the CNS following a stroke and can be adapted for other pathological conditions being studied. The technique presented uses laser excitation of the photosensitive dye Rose Bengal in vivo to induce a focal ischemic event in a single blood vessel. 
The video protocol demonstrates the preparation of a thin-skulled cranial window over the somatosensory cortex in a mouse for the induction of a Rose Bengal photothrombotic event keeping injury to the underlying dura matter and brain at a minimum. Surgical preparation is initially performed under a dissecting microscope with a custom-made surgical/imaging platform, which is then transferred to a confocal microscope equipped with an inverted objective adaptor. Representative images acquired utilizing this protocol are presented as well as time-lapse sequences of stroke induction. This technique is powerful in that the same area can be imaged repeatedly on subsequent days facilitating longitudinal in vivo studies of pathological processes following stroke.

Rose Bengal Photothrombosis by Confocal Optical Imaging In Vivo:  A Model of Single Vessel Stroke

Here, we describe a semi-invasive optical microscopy approach for the induction of a Rose Bengal photothrombotic clot in the somatosensory cortex of a mouse in vivo. The technical aspects of the imaging procedure are described from induction of a photothrombotic event to application and data collection.

In vivo imaging techniques have increased in utilization due to recent advances in imaging dyes and optical technologies, allowing for the ability to ...

Depletion of Mouse Cells from Human Tumor Xenografts Significantly Improves Downstream Analysis of Target Cells

The use of in vitro cell line models for cancer research has been a useful tool. However, it has been shown that these models fail to reliably mimic patient tumors in different assays1. Human tumor xenografts represent the gold standard with respect to tumor biology, drug discovery, and metastasis research 2-4. Tumor xenografts can be derived from different types of material like tumor cell lines, tumor tissue from primary patient tumors4 or serially transplanted tumors. When propagated in vivo, xenografted tissue is infiltrated and vascularized by cells of mouse origin. Multiple factors such as the tumor entity, the origin of xenografted material, growth rate and region of transplantation influence the composition and the amount of mouse cells present in tumor xenografts. However, even when these factors are kept constant, the degree of mouse cell contamination is highly variable.
Contaminating mouse cells significantly impair downstream analyses of human tumor xenografts. As mouse fibroblasts show high plating efficacies and proliferation rates, they tend to overgrow cultures of human tumor cells, especially slowly proliferating subpopulations. Mouse cell derived DNA, mRNA, and protein components can bias downstream gene expression analysis, next-generation sequencing, as well as proteome analysis 5. To overcome these limitations, we have developed a fast and easy method to isolate untouched human tumor cells from xenografted tumor tissue. This procedure is based on the comprehensive depletion of cells of mouse origin by combining automated tissue dissociation with the benchtop tissue dissociator and magnetic cell sorting. Here, we demonstrate that human target cells can be can be obtained with purities higher than 96% within less than 20 min independent of the tumor type.

Human tumor xenografts are vascularized and infiltrated by cells of mouse origin during the growth phase in vivo. To circumvent the bias caused by these contaminating cells during downstream analysis, we developed a method allowing for comprehensive depletion of all mouse cells by magnetic cell sorting.

The use of in vitro cell line models for cancer research has been a useful tool. However, it has been shown that these models fail to reliably mimic ...