Les auteurs voudrais remercier Yuliya Naumchuk (Loyola University Chicago) et Agne Žiniauskaitė (Experimentica Ltd.) pour l’excellent soutien technique et vidéographique. Programme de recherche du Dr Kaja est pris en charge par le Dr John P. et E. de Therese Mulcahy doué professeur en ophtalmologie à Loyola University Chicago.

Tous les animaux ont été traités conformément à la déclaration d’ARVO sur l’utilisation des animaux ophtalmique et Vision Research et la Directive européenne 86/609/CEE pour l’expérimentation animale, à l’aide de protocoles approuvé et contrôlé par le Conseil finlandais Animal Experiment.
1. induite par laser souris CNV modèle 5
<ol><li>Inspecter les yeux de l’animal macroscopiquement pour toute anomalie.</li>
	<li>Peser la souris.</li>
	<li>Calculer et préparer une quantité appropriée d’anesthésiques à utiliser, basé sur le poids de l’animal, par exemple un mélange de médétomidine (1 mg/kg), la kétamine (75 mg/kg) et l’eau distillée (solution de NaCl à 0,9 %) dans un rapport de 1:1.5:2.5, ou la kétamine (40 à 75 mg/kg), xylazine (5 mg/kg) et l’eau distillée (solution de NaCl à 0,9 %) à un ratio de 1 : 2. 5:1 ; pour une souris de 20 g, injecter 0,1 mL du mélange.</li>
	<li>Injecter par voie intrapéritonéale anesthésique.</li>
	<li>Replacez les souris dans la cage et d’attendre jusqu'à ce que l’animal est anesthésié. Confirmer que la souris est correctement anesthésiée par manque d’un réflexe de pédale.</li>
	<li>Assurer l’utilisation des équipements de protection individuelle sécurité laser.</li>
	<li>Allumer une lampe à fente et un laser à diode 532 nm.</li>
	<li>Retirer la souris de la cage et le déposer sur le coussin chauffant.</li>
	<li>Appliquer une goutte de Tropicamide pour la dilatation pupillaire. Attendre 3-5 min pour la dilatation pupillaire intégral (3 mm).</li>
	<li>Placez votre souris sur la scène de la lampe à fente.</li>
	<li>Placez une goutte de gel liquide ophtalmique sur un lamelle couvre-objet pour applanate la cornée.</li>
	<li>Orienter l’oeil de la souris avec la tête du nerf optique au centre.</li>
	<li>La valeur de la puissance du laser à 100 mW, la durée à 100 ms et la taille de tache à 50 µm.</li>
	<li>Concentrer le faisceau laser sur l’épithélium pigmentaire rétinien (RPE).</li>
	<li>Faire trois coups de laser dans un œil en évitant les vaisseaux sanguins rétiniens idéalement à la 4, 8 et 12:00 positions autour du nerf optique, respectivement. Après tous les coups pour absence d’hémorragie de la rétine au laser, vérifier le fond de le œil. Le œil controlatéral sert un contrôle non retiré.</li>
	<li>Jeter la souris lamelle couvre-objet et la place sur le coussin chauffant.</li>
	<li>Appliquez une goutte de gouttes de gel PEG sur les deux yeux.</li>
</ol>2. SD-OCT 6,7
<ol><li>Placez la souris dans l’étape de l’alignement de rongeurs et immobiliser la tête.</li>
	<li>Aligner l’objectif du système SD-OCT (p. ex., Bioptigen/Leica Envisu R2200) pour faire face à l’oeil pour l’imagerie in vivo à l’aide de contrôleurs X - et Y-étape.</li>
	<li>Effectuer des analyses pour vérifier les ruptures de la membrane de Bruch SD-OCT : une fois que le SD-OCT scanne l’oeil entier, déplacer manuellement la ligne de référence sur les sites lasered. Ruptures de la membrane de Bruch doivent être clairement visibles dans les zones lasered (voir Figure 1).</li>
</ol>3. fluorescéine angiographie 7,8,9
<ol><li>Retirer les souris avec le titulaire et placez-le sur le système de FA (p. ex., Heidelberg Spectralis HRA2).</li>
	<li>Focus au laser brûler les zones de le œil de le œil en utilisant le mode de réflectance infrarouge avec la tête du nerf optique au milieu de la fenêtre de visualisation.</li>
	<li>Injecter 0,1 mL de sel de sodium 5 % fluorescéine pour une souris de 20 g par voie sous-cutanée ou intrapéritonéale.</li>
	<li>Mettre l’accent sur le niveau de la choroïde.</li>
	<li>Prendre une image par rapport au niveau de la choroïde se concentrer.</li>
	<li>Recentrer au niveau rétinien et prendre la photo.</li>
	<li>Attendre 30 s et répéter les étapes 3,4 à 3,6.</li>
	<li>Retirez la souris du support et placez-la sur le coussin chauffant.</li>
	<li>Inverser l’anesthésie par α2-antagoniste de la médétomidine, Atipamézole (0,5 mg/kg, i.p.) ou attente de relance animale de l’anesthésie.</li>
	<li>Répéter en vivo SD-OCT et FA imagerie chez des animaux anesthésiés les jours suivi de 5, 10 et 14.</li>
</ol>4. CNV classement
<ol><li>Catégorie des dommages de la membrane de Bruch d’images OCT et choroïdienne FA prise immédiatement après le lasering au jour J0 comme suit : 0 - la membrane de Bruch n’était pas endommagée 1 - succès dommage de la membrane de Bruch</li>
	<li>Note la présence de NVC de taches lasered ayant une fuite observée en comparant la dynamique du signal de fluorescéine dans une série d’images rétiniennes de FA comme suit : 0 - aspect normal de la rétine 0,5 - coloration pâle de fuite 1.0 - zones CNV qui fuites Remarque : Utilisez l’imagerie OCT pour une confirmation supplémentaire de CNV ou en FA douteux où la présence de remaniements liquide en images OCT suggère CNV classement.</li>
</ol>5. mesures d’épaisseur rétinienne
<ol><li>Utiliser un logiciel de segmentation automatique pour des mesures d’épaisseur rétinienne. S’assurer que l’épaisseur totale de rétine est considéré, comme l’épaisseur de toutes les couches de la couche de fibres nerveuses à RPE (stations de mesure en bonne santé), ou à une ligne imaginaire reliant RPE autour du site de dommages (sites lasered) (voir aussi la Figure 7).</li>
</ol>

<ol>
	<li>Dobi, E. T., Puliafito, C. A., Destro, 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+new+model+of+experimental+choroidal+neovascularization+in+the+rat.">A new model of experimental choroidal neovascularization in the rat.</a> Arch. Ophthalmol. Chic. Ill 1960. 107, 264-269 (1989).</li><li>Tobe, 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=Evolution+of+neovascularization+in+mice+with+overexpression+of+vascular+endothelial+growth+factor+in+photoreceptors.">Evolution of neovascularization in mice with overexpression of vascular endothelial growth factor in photoreceptors.</a> Invest. Ophthalmol. Vis. Sci. 39, 180-188 (1998).</li><li>Seo, M. 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=Dramatic+inhibition+of+retinal+and+choroidal+neovascularization+by+oral+administration+of+a+kinase+inhibitor.">Dramatic inhibition of retinal and choroidal neovascularization by oral administration of a kinase inhibitor.</a> Am. J. Pathol. 154, 1743-1753 (1999).</li><li>Grossniklaus, H. E., Kang, S. J., Berglin, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Animal+models+of+choroidal+and+retinal+neovascularization.">Animal models of choroidal and retinal neovascularization.</a> Prog. Retin. Eye Res. 29, 500-519 (2010).</li><li>Shah, R. S., Soetikno, B. T., Lajko, M., Fawzi, A. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Mouse+Model+for+Laser-induced+Choroidal+Neovascularization.">A Mouse Model for Laser-induced Choroidal Neovascularization.</a> J Vis Exp. (106), e53502 (2015).</li><li>Giani, 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=In+vivo+evaluation+of+laser-induced+choroidal+neovascularization+using+spectral-domain+optical+coherence+tomography.">In vivo evaluation of laser-induced choroidal neovascularization using spectral-domain optical coherence tomography.</a> Invest. Ophthalmol. Vis. Sci. 52, 3880-3887 (2011).</li><li>Gong, Y., 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=Optimization+of+an+Image-Guided+Laser-Induced+Choroidal+Neovascularization+Model+in+Mice.">Optimization of an Image-Guided Laser-Induced Choroidal Neovascularization Model in Mice.</a> PloS One. 10, e0132643 (2015).</li><li>Sheets, K. 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=Neuroprotectin+D1+attenuates+laser-induced+choroidal+neovascularization+in+mouse.">Neuroprotectin D1 attenuates laser-induced choroidal neovascularization in mouse.</a> Mol. Vis. 16, 320-329 (2010).</li><li>Hoerster, R., 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=In-vivo+and+ex-vivo+characterization+of+laser-induced+choroidal+neovascularization+variability+in+mice.">In-vivo and ex-vivo characterization of laser-induced choroidal neovascularization variability in mice.</a> Graefes Arch. Clin. Exp. Ophthalmol. Albrecht Von Graefes Arch. Klin. Exp. Ophthalmol. 250, 1579-1586 (2012).</li><li>Sulaiman, R. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Simple+Optical+Coherence+Tomography+Quantification+Method+for+Choroidal+Neovascularization.">A Simple Optical Coherence Tomography Quantification Method for Choroidal Neovascularization.</a> J. Ocul. Pharmacol. Ther. Off. J. Assoc. Ocul. Pharmacol. Ther. Off. J. Assoc. Ocul. Pharmacol. 31, 447-454 (2015).</li></ol>

L’auteur Symantas Ragauskas, Ph.d. est employé (chercheur) et actionnaire de Experimentica Ltd. qui offre du contrat de services de recherche en utilisant le modèle préclinique de CNV utilisé dans cet Article.
L’auteur Eva Kielczewski est employé (ingénieur de recherche des applications, OCT) de Leica Microsystems qui produit des systèmes de SD-OCT utilisés dans cet Article.
L’auteur Joseph Vance est un employé (OCT NA Sales Director) de Leica Microsystems qui produit des systèmes de SD-OCT utilisés dans cet Article. Joseph Vance est également le Président et directeur général de sidération, LLC.
L’auteur Simon Kaja, Ph.d. est conseiller scientifique en chef et actionnaire de Experimentica Ltd., précliniques contrat organisme de recherche qui offre du contrat de services de recherche, y compris le modèle préclinique de la CNV utilisé dans cet article. Simon Kaja, Ph.d. est également CEO de K & P scientifique, LLC, un cabinet, sciences de la vie et sert pour le Dr John P. et Thérèse E. Mulcahy doué professeur en ophtalmologie à Loyola University Chicago Stritch School of Medicine. Les termes de cet arrangement ont été revus et approuvés par Loyola University Chicago conformément à sa politique de conflit d’intérêts.
L’auteur Giedrius Kalesnykas, Ph.d. est employé (CEO) et actionnaire de Experimentica Ltd. qui offre du contrat de services de recherche en utilisant le modèle préclinique de CNV utilisé dans cet Article.

Imagerie multimodale offre des outils précieux pour l’évaluation de pathologie CNV. Ici, nous avons présenté un protocole d’imagerie consistant en FA, SD-OCT et segmentation automatique pour l’évaluation rapide, reproductible et fiable de la pathologie de la CNV. Une rupture de la membrane de Bruch après que administration de laser a été confirmée. En outre, l’utilisation du SD-OCT à ce stade a également permis une visualisation immédiate de possibles hémorragies remaniements et sous-rétinienne, qui...

La première tentative réussie pour imiter la pathologie de la CNV humaine chez les rongeurs a été démontrée il y a près de trois décennies avec un laser krypton de rats Long-Evans1. Par la suite, un laser krypton servait à rompre la membrane de Bruch dans la souche de souris plus populaire, C57BL/6J2,3,4. Le taux de réussite de l’induction de la CNV a été vérifié avec FA et taches histologiques. Un développement rapide des modalités d’imagerie non invasives, tels que les PTOM, favorisé la croissance du champ des modèles précliniques de rongeurs. La capacité de surveiller les changements morphologiques dans la rétine à plusieurs moments dans l’oeil même significativement contribue à la réduction de l’utilisation des animaux et augmente l’efficacité dans des études expérimentales. Une évaluation histologique des lésions de la CNV est plutôt simple et exige le marquage de la croissance vasculaire anormale autour du site d’administration de laser, acquisition d’images et estimation de surface/volume à l’aide d’un logiciel d’analyse image. En revanche, les modalités d’imagerie in vivo introduisent des analyses plus complexes de la pathologie de la CNV et son interprétation.
Nous présentons ici une méthode simple et relativement rapide d’induction de grade, la progression et la régression de la CNV à l’aide de la FA, SD-OCT, et la méthode de segmentation automatique chez la souris laser-induced CNV modèle.

<table border="0" cellpadding="0" cellspacing="0" width="917">
	<tbody>
		<tr height="40">
			<td height="40" style="height:40px;width:275px;">Medetomidine (commercial name Domitor)</td>
			<td style="width:123px;">Orion</td>
			<td style="width:344px;">Vnr 01 56 02</td>
			<td style="width:177px;">Anesthesia</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Ketamine</td>
			<td>Intervet</td>
			<td>Vnr 51 14 85</td>
			<td>Anesthesia</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">0,9% NaCl</td>
			<td>B Braun</td>
			<td>357 0340</td>
			<td>Anesthesia</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Xylazine (commercial name Rompun vet)</td>
			<td>Bayer</td>
			<td>vnr 14 89 99</td>
			<td>Anesthesia</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Tropicamide</td>
			<td>Santen</td>
			<td>Vnr 04 12 36</td>
			<td>Mydriatic agent</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Viscotears</td>
			<td>Alcon</td>
			<td>Vnr 44 54 81</td>
			<td>Lubricant</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Systane</td>
			<td>Alcon</td>
			<td>&#160;-</td>
			<td>Lubricant</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">5% Fluorescein sodium salt</td>
			<td>Sigma Aldrich</td>
			<td>F6377-100G</td>
			<td>Fluoresent agent</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Atipamezole (commercial name Antisedane)</td>
			<td>Orion</td>
			<td>Vnr 47 19 53</td>
			<td>Anesthesia</td>
		</tr>
	</tbody>
</table>

in vivo multimodal imaging and analysis of mouse laser-induced choroidal neovascularization model

Induite par laser de néovascularisation choroïdienne (NVC) est un modèle bien établi pour imiter la forme humide de la dégénérescence maculaire liée à l’âge (DMLA). Dans ce protocole, notre objectif est de guider le lecteur non pas simplement par le biais de considérations techniques de générer des lésions induites par le laser pour déclencher des processus néovasculaire, mais plutôt se concentrer sur l’information puissants qui peut être obtenue au multimodal longitudinale in vivo imagerie tout au long de la période de suivi.
La souris induite par laser modèle CNV a été générée par une administration de laser de diode. Techniques d’imagerie multimodale en vivo ont été utilisés pour surveiller l’induction, la progression et la régression CNV. Tout d’abord, tomographie à cohérence optique domaine spectral (SD-OCT) ont été effectuée immédiatement après la lasering pour vérifier une rupture de la membrane de Bruch. Subséquent en vivo imagerie utilisant l’angiographie à la fluorescéine (FA) a confirmé des dommages réussi de la membrane de Bruch de série images acquises au niveau choroïdienne. Suivi longitudinal de la prolifération de la CNV et régression sur 5, 10 et 14 jours après le lasering a effectué un SD-OCT et FA. Simple et fiable de classement de leaky leasions CNV d’images de FA sont présenté. Segmentation automatique pour la mesure de l’épaisseur totale de rétine, combinée avec application de calibre manuel pour le mesurage de l’épaisseur rétinienne aux sites de la CNV, permettent une évaluation impartiale de la présence de le œdème. Enfin, vérification histologique du CNV est effectuée à l’aide d’isolectine GS-IB4 coloration sur flatmounts choroïdienne. La coloration est binariser, et la zone isolectine-positif est calculée avec ImageJ.
Ce protocole est particulièrement utile dans les études thérapeutiques nécessitant haut-débit comme dépistage de pathologie de la CNV, car elle permet de vite, multimodal et classification fiable de l’oedème de pathologie et de la rétine CNV. En outre, haute résolution SD-OCT permet l’enregistrement d’autres caractéristiques pathologiques, tels que l’accumulation de liquide sous-rétinienne ou remaniements. Cependant, cette méthode n’offre pas la possibilité d’automatiser CNV volume analyse des images SD-OCT, qui doit être effectuée manuellement.

Une bulle ou subretinal saignement immédiatement après lasering n’est pas toujours visible. SD-OCT est donc particulièrement important pour vérifier les dommages de la membrane de Bruch. Figure 1 montre un exemple de l’imagerie OCT à des moments différents après l’administration de laser.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/56173/56173fig1.jpg"> <strong class="...

Watch this Scientific Journal Video about In Vivo Multimodal Imaging and Analysis of Mouse Laser-Induced Choroidal Neovascularization Model at JoVE.com

In Vivo Multimodal Imaging and Analysis of Mouse Laser-Induced Choroidal Neovascularization Model

In Vivo Imagerie multimodale et analyse du modèle de néovascularisation choroïdienne souris induite par Laser

Nous présentons ici l’utilité de longitudinal en vivo imagerie dans le suivi des modifications morphologiques de la néovascularisation choroïdienne induite par laser chez les souris.

Laser-induced choroidal neovascularization (CNV) is a well-established model to mimic the wet form of age-related macular degeneration (AMD). In this ...

in-vivo-multimodal-imaging-analysis-mouse-laser-induced-choroidal

Research

JoVE Journal

Neuroscience

In Vivo Multimodal Imaging and Analysis of Mouse Laser-Induced Choroidal Neovascularization Model

9.0K vues.  Experimentica Ltd.. Nous présentons ici l’utilité de longitudinal en vivo imagerie dans le suivi des modifications morphologiques de la néovascularisation choroïdienne induite par laser chez les souris.

Vidéo: In Vivo Multimodal Imaging and Analysis of Mouse Laser-Induced Choroidal Neovascularization Model

Multiple-mouse Neuroanatomical Magnetic Resonance Imaging

The field of mouse phenotyping with magnetic resonance imaging (MRI) is rapidly growing, motivated by the need for improved tools for characterizing and evaluating mouse models of human disease. MRI is an excellent modality for investigating genetically altered animals. It is capable of whole brain coverage, can be used in vivo, and provides multiple contrast mechanisms for investigating different aspects of neuranatomy and physiology. The advent of high-field scanners along with the ability to scan multiple mice simultaneously allows for rapid phenotyping of novel mutations.
Effective mouse MRI studies require attention to many aspects of experiment design. In this article, we will describe general methods to acquire quality images for mouse phenotyping using a system that images mice concurrently in shielded transmit/receive radio frequency (RF) coils in a common magnet (Bock et al., 2003). We focus particularly on anatomical phenotyping, an important and accessible application that has shown a high potential for impact in many mouse models at our imaging centre. Before we can provide the detailed steps to acquire such images, there are important practical considerations for both in vivo brain imaging (Dazai et al., 2004) and ex vivo brain imaging (Spring et al., 2007) that should be noted. These are discussed below.

Magnetic resonance imaging (MRI) has become an increasingly popular tool for examining the phenotype of genetically altered mice. This article illustrates the methods necessary to achieve high-throughput phenotyping of genetically altered mice using multiple-mouse MRI.

Multiple-Mouse Imaging neuroanatomiques par résonance magnétique

The field of mouse phenotyping with magnetic resonance imaging (MRI) is rapidly growing, motivated by the need for improved tools for characterizing and ...

Recherche

Neurosciences

Multimodal Imaging of Stem Cell Implantation in the Central Nervous System of Mice

During the past decade, stem cell transplantation has gained increasing interest as primary or secondary therapeutic modality for a variety of diseases, both in preclinical and clinical studies. However, to date results regarding functional outcome and/or tissue regeneration following stem cell transplantation are quite diverse. Generally, a clinical benefit is observed without profound understanding of the underlying mechanism(s)1. Therefore, multiple efforts have led to the development of different molecular imaging modalities to monitor stem cell grafting with the ultimate aim to accurately evaluate survival, fate and physiology of grafted stem cells and/or their micro-environment. Changes observed in one or more parameters determined by molecular imaging might be related to the observed clinical effect. In this context, our studies focus on the combined use of bioluminescence imaging (BLI), magnetic resonance imaging (MRI) and histological analysis to evaluate stem cell grafting.
BLI is commonly used to non-invasively perform cell tracking and monitor cell survival in time following transplantation2-7, based on a biochemical reaction where cells expressing the Luciferase-reporter gene are able to emit light following interaction with its substrate (e.g. D-luciferin)8, 9. MRI on the other hand is a non-invasive technique which is clinically applicable10 and can be used to precisely locate cellular grafts with very high resolution11-15, although its sensitivity highly depends on the contrast generated after cell labeling with an MRI contrast agent. Finally, post-mortem histological analysis is the method of choice to validate research results obtained with non-invasive techniques with highest resolution and sensitivity. Moreover end-point histological analysis allows us to perform detailed phenotypic analysis of grafted cells and/or the surrounding tissue, based on the use of fluorescent reporter proteins and/or direct cell labeling with specific antibodies.
In summary, we here visually demonstrate the complementarities of BLI, MRI and histology to unravel different stem cell- and/or environment-associated characteristics following stem cell grafting in the CNS of mice. As an example, bone marrow-derived stromal cells, genetically engineered to express the enhanced Green Fluorescent Protein (eGFP) and firefly Luciferase (fLuc), and labeled with blue fluorescent micron-sized iron oxide particles (MPIOs), will be grafted in the CNS of immune-competent mice and outcome will be monitored by BLI, MRI and histology (Figure 1).

This article describes an optimized sequence of events for multimodal imaging of cellular grafts in rodent brain using: (i) in vivo bioluminescence and magnetic resonance imaging, and (ii) post mortem histological analysis. Combining these imaging modalities on a single animal allows cellular graft evaluation with high resolution, sensitivity and specificity.

Imagerie multimodale d&#39;implantation de cellules souches dans le système nerveux central de souris

During the past decade, stem cell transplantation has gained increasing interest as primary or secondary therapeutic modality for a variety of diseases, ...

Functional Neuroimaging Using Ultrasonic Blood-brain Barrier Disruption and Manganese-enhanced MRI

Although mice are the dominant model system for studying the genetic and molecular underpinnings of neuroscience, functional neuroimaging in mice remains technically challenging. One approach, Activation-Induced Manganese-enhanced MRI (AIM MRI), has been used successfully to map neuronal activity in rodents 1-5. In AIM MRI, Mn2+ acts a calcium analog and accumulates in depolarized neurons 6,7. Because Mn2+ shortens the T1 tissue property, regions of elevated neuronal activity will enhance in MRI. Furthermore, Mn2+ clears slowly from the activated regions; therefore, stimulation can be performed outside the magnet prior to imaging, enabling greater experimental flexibility. However, because Mn2+ does not readily cross the blood-brain barrier (BBB), the need to open the BBB has limited the use of AIM MRI, especially in mice.
One tool for opening the BBB is ultrasound. Though potentially damaging, if ultrasound is administered in combination with gas-filled microbubbles (i.e., ultrasound contrast agents), the acoustic pressure required for BBB opening is considerably lower. This combination of ultrasound and microbubbles can be used to reliably open the BBB without causing tissue damage 8-11.
Here, a method is presented for performing AIM MRI by using microbubbles and ultrasound to open the BBB. After an intravenous injection of perflutren microbubbles, an unfocused pulsed ultrasound beam is applied to the shaved mouse head for 3 minutes. For simplicity, we refer to this technique of BBB Opening with Microbubbles and UltraSound as BOMUS 12. Using BOMUS to open the BBB throughout both cerebral hemispheres, manganese is administered to the whole mouse brain. After experimental stimulation of the lightly sedated mice, AIM MRI is used to map the neuronal response.
To demonstrate this approach, herein BOMUS and AIM MRI are used to map unilateral mechanical stimulation of the vibrissae in lightly sedated mice 13. Because BOMUS can open the BBB throughout both hemispheres, the unstimulated side of the brain is used to control for nonspecific background stimulation. The resultant 3D activation map agrees well with published representations of the vibrissae regions of the barrel field cortex 14. The ultrasonic opening of the BBB is fast, noninvasive, and reversible; and thus this approach is suitable for high-throughput and/or longitudinal studies in awake mice.

A technique is described for broadly opening the blood-brain barrier in the mouse using microbubbles and ultrasound. Using this technique, manganese can be administered to the mouse brain. Because manganese is an MRI contrast agent that accumulates in depolarized neurons, this approach enables imaging of neuronal activity.

Utilisation de neuro-imagerie fonctionnelle par ultrasons rupture de la barrière hémato-encéphalique et le manganèse-IRM

Although mice are the dominant model system for studying the genetic and molecular underpinnings of neuroscience, functional neuroimaging in mice remains ...

Ex vivo Live Imaging of Single Cell Divisions in Mouse Neuroepithelium

We developed a system that integrates live imaging of fluorescent markers and culturing slices of embryonic mouse neuroepithelium. We took advantage of existing mouse lines for genetic cell lineage tracing: a tamoxifen-inducible Cre line and a Cre reporter line expressing dsRed upon Cre-mediated recombination. By using a relatively low level of tamoxifen, we were able to induce recombination in a small number of cells, permitting us to follow individual cell divisions. Additionally, we observed the transcriptional response to Sonic Hedgehog (Shh) signaling using an Olig2-eGFP transgenic line 1-3 and we monitored formation of cilia by infecting the cultured slice with virus expressing the cilia marker, Sstr3-GFP 4. In order to image the neuroepithelium, we harvested embryos at E8.5, isolated the neural tube, mounted the neural slice in proper culturing conditions into the imaging chamber and performed time-lapse confocal imaging. Our ex vivo live imaging method enables us to trace single cell divisions to assess the relative timing of primary cilia formation and Shh response in a physiologically relevant manner. This method can be easily adapted using distinct fluorescent markers and provides the field the tools with which to monitor cell behavior in situ and in real time.

Ex vivo Live Imaging of Single Cell Divisions in Mouse Neuroepithelium

Here we develop the tools necessary for ex vivo live imaging to trace single cell divisions in the mouse E8.5 neuroepithelium

Ex vivo d&#39;imagerie en temps réel de simples divisions cellulaires dans neuroépithélium de souris

We developed a system that integrates live imaging of fluorescent markers and culturing slices of embryonic mouse neuroepithelium. We took advantage of ...

An Ex Vivo Laser-induced Spinal Cord Injury Model to Assess Mechanisms of Axonal Degeneration in Real-time

Injured CNS axons fail to regenerate and often retract away from the injury site. Axons spared from the initial injury may later undergo secondary axonal degeneration. Lack of growth cone formation, regeneration, and loss of additional myelinated axonal projections within the spinal cord greatly limits neurological recovery following injury. To assess how central myelinated axons of the spinal cord respond to injury, we developed an ex vivo living spinal cord model utilizing transgenic mice that express yellow fluorescent protein in axons and a focal and highly reproducible laser-induced spinal cord injury to document the fate of axons and myelin (lipophilic fluorescent dye Nile Red) over time using two-photon excitation time-lapse microscopy. Dynamic processes such as acute axonal injury, axonal retraction, and myelin degeneration are best studied in real-time. However, the non-focal nature of contusion-based injuries and movement artifacts encountered during in vivo spinal cord imaging make differentiating primary and secondary axonal injury responses using high resolution microscopy challenging. The ex vivo spinal cord model described here mimics several aspects of clinically relevant contusion/compression-induced axonal pathologies including axonal swelling, spheroid formation, axonal transection, and peri-axonal swelling providing a useful model to study these dynamic processes in real-time. Major advantages of this model are excellent spatiotemporal resolution that allows differentiation between the primary insult that directly injures axons and secondary injury mechanisms; controlled infusion of reagents directly to the perfusate bathing the cord; precise alterations of the environmental milieu (e.g., calcium, sodium ions, known contributors to axonal injury, but near impossible to manipulate in vivo); and murine models also offer an advantage as they provide an opportunity to visualize and manipulate genetically identified cell populations and subcellular structures. Here, we describe how to isolate and image the living spinal cord from mice to capture dynamics of acute axonal injury.

An Ex Vivo Laser-induced Spinal Cord Injury Model to Assess Mechanisms of Axonal Degeneration in Real-time

We present a protocol utilizing two-photon excitation time-lapse microscopy to simultaneously visualize the dynamics of axon and myelin injuries in real time. This proposed protocol permits studies of both intrinsic and extrinsic factors which can influence central myelinated axon fate after injury and contribute to permanent clinical disability.

Une<em&gt; Ex Vivo</em&gt; Induite par laser Spinal Cord Injury modèle pour évaluer les mécanismes de la dégénérescence axonale dans en temps réel

Injured CNS axons fail to regenerate and often retract away from the injury site. Axons spared from the initial injury may later undergo secondary axonal ...

3-D Imaging and Analysis of Neurons Infected In Vivo with Toxoplasma gondii

Toxoplasma gondii is an obligate, intracellular parasite with a broad host range, including humans and rodents. In both humans and rodents, Toxoplasma establishes a lifelong persistent infection in the brain. While this brain infection is asymptomatic in most immunocompetent people, in the developing fetus or immunocompromised individuals such as acquired immune deficiency syndrome (AIDS) patients, this predilection for and persistence in the brain can lead to devastating neurologic disease. Thus, it is clear that the brain-Toxoplasma interaction is critical to the symptomatic disease produced by Toxoplasma, yet we have little understanding of the cellular or molecular interaction between cells of the central nervous system (CNS) and the parasite. In the mouse model of CNS toxoplasmosis it has been known for over 30 years that neurons are the cells in which the parasite persists, but little information is available about which part of the neuron is generally infected (soma, dendrite, axon) and if this cellular relationship changes between strains. In part, this lack is secondary to the difficulty of imaging and visualizing whole infected neurons from an animal. Such images would typically require serial sectioning and stitching of tissue imaged by electron microscopy or confocal microscopy after immunostaining. By combining several techniques, the method described here enables the use of thick sections (160 &#181;m) to identify and image whole cells that contain cysts, allowing three-dimensional visualization and analysis of individual, chronically infected neurons without the need for immunostaining, electron microscopy, or serial sectioning and stitching. Using this technique, we can begin to understand the cellular relationship between the parasite and the infected neuron.

3-D Imaging and Analysis of Neurons Infected In Vivo with Toxoplasma gondii

Using this protocol, we were able to image 160 &#181;m thick brain sections from mice infected with the parasite Toxoplasma gondii, which enables visualization and analysis of the spatial relationship between the encysting parasite and the infected neuron.

Imagerie 3-D et de l&#39;analyse des neurones infecté<em&gt; In Vivo</em&gt; Avec<em&gt; Toxoplasma gondii</em

Toxoplasma gondii is an obligate, intracellular parasite with a broad host range, including humans and rodents. In both humans and rodents, Toxoplasma ...

M&#252;ller Glia Cell Activation in a Laser-induced Retinal Degeneration and Regeneration Model in Zebrafish

A fascinating difference between teleost and mammals is the lifelong potential of the teleost retina for retinal neurogenesis and regeneration after severe damage. Investigating the regeneration pathways in zebrafish might bring new insights to develop innovative strategies for the treatment of retinal degenerative diseases in mammals. Herein, we focused on the induction of a focal lesion to the outer retina in adult zebrafish by means of a 532 nm diode laser. A localized injury allows investigating biological processes that take place during retinal degeneration and regeneration directly at the area of damage. Using non-invasive optical coherence tomography (OCT), we were able to define the location of the damaged area and monitor subsequent regeneration in vivo. Indeed, OCT imaging produces high-resolution, cross-sectional images of the zebrafish retina, providing information which was previously only available with histological analyses. In order to confirm the data from real-time OCT, histological sections were performed and regenerative response after the induction of the retinal injury was investigated by immunohistochemistry.

The zebrafish is a popular animal model to study mechanisms of retinal degeneration/regeneration in vertebrates. This protocol describes a method to induce localized injury disrupting the outer retina with minimal damage to the inner retina. Subsequently, we monitor in vivo the retinal morphology and the M&#252;ller glia response throughout retinal regeneration.

Activation des cellules Müller Glia dans une dégénérescence rétinienne induite par Laser et le modèle de régénération chez le poisson zèbre

A fascinating difference between teleost and mammals is the lifelong potential of the teleost retina for retinal neurogenesis and regeneration after ...

Laser-Induced Brain Injury in the Motor Cortex of Rats

A common technique for inducing stroke in experimental rodent models involves the transient (often denoted as MCAO-t) or permanent (designated as MCAO-p) occlusion of the middle cerebral artery (MCA) using a catheter. This generally accepted technique, however, has some limitations, thereby limiting its extensive use. Stroke induction by this method is often characterized by high variability in the localization and size of the ischemic area, periodical occurrences of hemorrhage, and high death rates. Also, the successful completion of any of the transient or permanent procedures requires expertise and often lasts for about 30 minutes. In this protocol, a laser irradiation technique is presented that can serve as an alternative method for inducing and studying brain injury in rodent models.
When compared to rats in the control and MCAO groups, the brain injury by laser induction showed reduced variability in body temperature, infarct volume, brain edema, intracranial hemorrhage, and mortality. Furthermore, the use of a laser-induced injury caused damage to the brain tissues only in the motor cortex unlike in the MCAO experiments where destruction of both the motor cortex and striatal tissues is observed.
Findings from this investigation suggest that laser irradiation could serve as an alternative and effective technique for inducing brain injury in the motor cortex. The method also shortens the time for completing the procedure and does not require expert handlers.

The protocol presented here shows a technique to create a rodent model of brain injury. The method described here uses laser irradiation and targets motor cortex.

Lésion cérébrale induite au laser dans le cortex moteur des rats

A common technique for inducing stroke in experimental rodent models involves the transient (often denoted as MCAO-t) or permanent (designated as MCAO-p) ...

Imaging and Analysis of Neurofilament Transport in Excised Mouse Tibial Nerve

Neurofilament protein polymers move along axons in the slow component of axonal transport at average speeds of ~0.35-3.5 mm/day. Until recently the study of this movement in situ was only possible using radioisotopic pulse-labeling, which permits analysis of axonal transport in whole nerves with a temporal resolution of days and a spatial resolution of millimeters. To study neurofilament transport in situ with higher temporal and spatial resolution, we developed a hThy1-paGFP-NFM transgenic mouse that expresses neurofilament protein M tagged with photoactivatable GFP in neurons. Here we describe fluorescence photoactivation pulse-escape and pulse-spread methods to analyze neurofilament transport in single myelinated axons of tibial nerves from these mice ex vivo. Isolated nerve segments are maintained on the microscope stage by perfusion with oxygenated saline and imaged by spinning disk confocal fluorescence microscopy. Violet light is used to activate the fluorescence in a short axonal window. The fluorescence in the activated and flanking regions is analyzed over time, permitting the study of neurofilament transport with temporal and spatial resolution on the order of minutes&#160;and microns, respectively. Mathematical modeling can be used to extract kinetic parameters of neurofilament transport including the velocity, directional bias and pausing behavior from the resulting data. The pulse-escape and pulse-spread methods can also be adapted to visualize neurofilament transport in other nerves. With the development of additional transgenic mice, these methods could also be used to image and analyze the axonal transport of other cytoskeletal and cytosolic proteins in axons.

We describe fluorescence photoactivation methods to analyze the axonal transport of neurofilaments in single myelinated axons of peripheral nerves from transgenic mice that express a photoactivatable neurofilament protein.

Imagerie et analyse du transport neurofilament dans le nerf tibial de souris excisée

Neurofilament protein polymers move along axons in the slow component of axonal transport at average speeds of ~0.35-3.5 mm/day. Until recently the study ...

Transpupillary Two-Photon In Vivo Imaging of the Mouse Retina

The retina transforms light signals from the environment into electrical signals that are propagated to the brain. Diseases of the retina are prevalent and cause visual impairment and blindness. Understanding how such diseases progress is critical to formulating new treatments. In vivo&#160;microscopy in animal models of disease is a powerful tool for understanding neurodegeneration and has led to important progress towards treatments of conditions ranging from Alzheimer&#39;s disease to stroke. Given that the retina is the only central nervous system structure inherently accessible by optical approaches, it naturally lends itself towards in vivo imaging. However, the native optics of the lens and cornea present some challenges for effective imaging access.
This protocol outlines methods for in vivo two-photon imaging of cellular cohorts and structures in the mouse retina at cellular resolution, applicable for both acute- and chronic-duration imaging experiments. It presents examples of retinal ganglion cell (RGC), amacrine cell, microglial, and vascular imaging using a suite of labeling techniques including adeno-associated virus (AAV) vectors, transgenic mice, and inorganic dyes. Importantly, these techniques extend to all cell types of the retina, and suggested methods for accessing other cellular populations of interest are described. Also detailed are example strategies for manual image postprocessing for display and quantification. These techniques are directly applicable to studies of retinal function in health and disease.

In vivo imaging is a powerful tool for the study of biology in health and disease. This protocol describes transpupillary imaging of the mouse retina with a standard two-photon microscope. It also demonstrates different in vivoimaging methods to fluorescently label multiple cellular cohorts of the retina.

Transpupillaire Imagerie in vivo à deux photons de la rétine de souris

The retina transforms light signals from the environment into electrical signals that are propagated to the brain. Diseases of the retina are prevalent ...