Nous remercions Karine Kindbeiter, Muriel Bozon, et Florie Reynaud pour leur aide. Le travail est soutenu par le CNRS, le programme ANR YODA et Labex DevWeCan.

JOUR 1 Une. Dissection de la moelle épinière étage Plate (FP) de E12.5 embryons de souris Remarque: L&#39;ensemble de la procédure nécessite l&#39;utilisation de conditions stériles. Il est préférable d&#39;effectuer la dissection sous une hotte à dissection pour éviter la contamination. La surface de la hotte doit être nettoyé avec de l&#39;éthanol. Tous les instruments de dissection doivent être stérilisés et conservés dans une boîte de Pétri stérile. Les liquides (milieu, le milieu de dissection) doivent être maintenus fermés et mis dans un bain de glace. Chaque embryon doit être recueilli dans goutte frais individu. Ceci est important pour la préservation des tissus. La dissection est réalisée avec Dumont # 5 forceps. Pour transférer les embryons entre plats, saisir le cordon ombilical ou la tête sans aucun dommage pour le cerveau postérieur. Il est essentiel de ne pas endommager la moelle épinière pour mener à bien la dissection. Préparer froid tampon phosphate salin (PBS), solution saline équilibrée de Hank froide (HBSS) -6,5% de glucose et d&#39;une salle moyenne neurobasal de température. 1.1 vertébrale dissection du cordon Les animaux sont traités selon les directives de protection des animaux du Centre National de la Recherche Scientifique suivantes directives européennes. Le procédé de l&#39;euthanasie est dislocation cervicale, il consiste à appliquer une pression sur le col et la dislocation de la colonne vertébrale à partir du cerveau. Cette méthode est recommandée pour les modèles animaux de la souris, et peut être effectuée d&#39;une manière rapide et efficace. <ol><li> Euthanasier une souris enceinte à E12.5 de gestation (0,5 ME = nattes premier jour suivant). Placez la souris face ventrale. </li><li> Faire tremper l&#39;abdomen avec 70% d&#39;éthanol. Pincer la peau de l&#39;abdomen avec une pince Adson et couper à travers la peau et les couches péritonéale avec des ciseaux chirurgicaux. Faire une incision et l&#39;utiliser pour couper des deux côtés de la souris pour exposer la cavité abdominale. </li><li> Une chaîne d&#39;embryons est présent sur chaque côté de la souris. Saisissez une corne de l&#39;uterus dans le tissu entre les deux embryons et disséquer rupture à partir de la partie extérieure. Transférer l&#39;utérus intact pour une boîte de Pétri de 100 mm avec du PBS froid sur la glace. </li><li> Extraire les embryons à partir de tissus extra-embryonnaires. Saisissez le tissu placentaire (en rouge foncé) avec deux paires de pinces et tirez doucement pour déchirer le tissu et éliminer les embryons du sac de l&#39;utérus. </li></ol> Remarque: Pour une meilleure conservation, la collecte des embryons de leur utérus sac un par un. <ol start="5"><li> Les prochaines étapes sont effectuées sous loupe binoculaire et dissection capot. Placez un embryon dans une goutte de froid HBSS-glucose 6,5%. </li><li> En utilisant des pinces, décapiter l&#39;embryon. </li></ol> Remarque: Couper entre la mâchoire inférieure et le cerveau postérieur, la partie postérieure de la rhombencéphale est important pour les prochaines étapes. <ol start="7"><li> Placez l&#39;embryon face ventrale vers le bas avec la partie antérieure face à l&#39;expérimentateur. </li><li> Pincer la peaude l&#39;embryon avec une paire de forceps et avec l&#39;autre paire se détacher de la peau. </li></ol> Remarque: Cette étape doit être répétée jusqu&#39;à ce que la peau est complètement retiré de la partie antérieure de l&#39;embryon. <ol start="9"><li> Tournez le côté embryon antérieure à la gauche. Avec une pince &quot;cerner&quot; l&#39;embryon dans la partie antérieure. Avec les autres pinces saisissent la peau et tirez vers le côté rostral de l&#39;embryon. La moelle épinière est alors accessible. </li><li> Utilisez un côté de la pince pour couper les méninges qui enveloppent encore la moelle épinière. La moelle épinière est maintenant ouvert. </li><li> Tournez le côté embryon antérieure à la droite. </li><li> Détacher le tissu de la moelle épinière à partir du côté du col de l&#39;embryon. Faites glisser la pince sous la moelle épinière (les pinces doivent être tenus fermés pour éviter d&#39;endommager la moelle épinière). Les pinces doivent être visibles dans la moelle épinière. Petits mouvements de rotation en vertu de la moelle épinière sont suffisantes pour détacher latissu et le ganglion de la racine dorsale (DRG) entourant. </li></ol> Remarque: Laisser les tissus environnants attaché ajouter du poids à la moelle épinière, ce qui augmente la probabilité de casser lors de l&#39;étape suivante. <ol start="13"><li> Placez la moelle épinière isolée dans une nouvelle goutte de froid HBSS-glucose 6,5%. </li><li> Placer la colonne vertébrale dans une position à plat, les méninges sur la face supérieure et antérieure à une distance à partir de l&#39;expérimentateur. </li><li> &quot;Cerner&quot; la moelle épinière à l&#39;aide du cerveau postérieur restant avec une pince, et avec les deuxièmes pinces saisissent les méninges. Décoller les méninges à partir du côté rostrale de la moelle épinière. </li></ol> Remarque: le mouvement doit être lente et constante afin d&#39;éviter toute rupture de la moelle épinière. Mouvements vibratoires peuvent faciliter le détachement des méninges. 1.2 FP dissection <ol><li> Pincez le cerveau postérieur avec une pince. </li><li> Le FP est la tra centralnsparent partie du tissu. Avec un scalpel découper la plaque de sol. </li></ol> Remarque: Pour couper les deux côtés avec la même qualité, commencer par la face rostrale et couper alternativement du côté droit et le côté gauche de la plaque de sol. <ol start="3"><li> Conserver la FP disséqué en milieu Neurobasal à la température ambiante. </li></ol> 2. FP Culture Remarque: Toutes les mesures doivent être effectuées dans des conditions stériles dans une hotte de culture de tissu. Utilisez milieu frais et les suppléments et les réactifs fraîchement décongelé. Préparer des lamelles de verre stériles, neurobasal chaud + B27, le plasma et HBSS-thrombine. 2.1 FP culture <ol><li> Placer plusieurs lamelles stériles dans une boîte de Petri de 100 mm et la pipette 20 ul de plasma dans le centre de chaque lamelle. </li><li> Transfert de deux à quatre FP dans chaque goutte de plasma et d&#39;ajouter 20 ul de HBSS-thrombine à côté de la chute de plasma et mélanger soigneusement. Gardez les lamellespendant au moins dix minutes à température ambiante pour permettre la coagulation du plasma. </li></ol> Remarque: Le transfert de deux MF en cas de dissection complète et plus en cas de dissection partielle. Mélanger doucement avec une pipette et éviter tout contact avec des explants de PF. Le caillot de plasma se rétracte quelques um comme un signe de la coagulation. La coagulation ne doit pas être interrompue prématurément, afin d&#39;éviter le détachement du caillot de plasma. <ol start="3"><li> Transférer chaque lamelle dans une plaque de 24 puits et ajouter 500 ul de Neurobasal + B27. Incuber 48 heures à 37 ° C. </li></ol> JOUR 3 3. FP milieu conditionné (FP cm) récolte Remarque: La récolte doit être effectuée dans des conditions stériles dans une hotte de culture de tissu. Si le surnageant est contaminé ou si les plaques de sol sont flottantes (ce qui signifie qu&#39;ils aurait pu mourir pendant les péri de la cultureod) alors ne pas récolter la FP cm à partir de ce bien. 3.1 FP cm récolte <ol><li> Récolter soigneusement le milieu de chaque puits. </li></ol> Note: Ne pas pipeter le mélange plasma-thrombine polymérisé ou des fragments de PF. <ol start="2"><li> Stocker des aliquotes de 100 ul à -80 ° C. </li></ol> JOUR 4 4. Dissection de la moelle épinière Commissural neurones de E12.5 embryons de souris Remarque: Cette préparation n&#39;a pas besoin d&#39;être effectuées dans des conditions stériles. Suivez la procédure décrite ci-dessus pour recueillir les embryons. Préparer PBS froid, froid HBSS-6.5% de glucose et neurobasal froid. 4.1 vertébrale dissection du cordon <ol><li> En utilisant des pinces, décapiter l&#39;embryon. </li></ol> Remarque: Couper entre la mâchoire inférieure et le cerveau postérieur, la partie postérieure du cerveau postérieur est important pour l&#39;prochaines étapes. <ol start="2"><li> Placez l&#39;embryon face ventrale dans une nouvelle chute avec la partie antérieure face à l&#39;expérimentateur. </li><li> Pincer la peau de l&#39;embryon avec une pince et l&#39;autre se détacher de la peau. </li></ol> Remarque: Cette étape doit être répétée jusqu&#39;à ce que la peau est complètement retiré de la partie antérieure de l&#39;embryon. <ol start="4"><li> Tournez le côté embryon antérieure à la gauche. Avec une pince &quot;cerner&quot; l&#39;embryon dans la partie antérieure. Avec les autres pinces, saisir la peau et tirez vers le côté rostral de l&#39;embryon, d&#39;exposer la moelle épinière. </li><li> Utilisez un côté de la pince pour couper les méninges qui enveloppent encore la moelle épinière. La moelle épinière est maintenant exposée et ouverte. </li><li> Placez la face antérieure de l&#39;embryon vers la droite. </li><li> Détacher le tissu de la moelle épinière à partir du côté du col de l&#39;embryon. Faites glisser la pince sous la moelle épinière (maintenir la pince fermée). Pourcèpes doivent visible sous la moelle épinière. Petits mouvements de rotation en vertu de la moelle épinière sont suffisantes pour détacher le tissu adjacent et le ganglion de la racine dorsale (DRG). </li><li> Transférer la moelle épinière isolée dans une nouvelle goutte de froid HBSS-glucose 6,5%. </li><li> Placer la colonne vertébrale dans une position à plat, les méninges sur la face supérieure et antérieure à une distance à partir de l&#39;expérimentateur. </li><li> &quot;Cerner&quot; la moelle épinière à l&#39;aide du cerveau postérieur restant avec une pince, avec les deuxièmes pinces saisissent les méninges. Décoller les méninges à partir du côté rostrale de la moelle épinière. </li></ol> 4.2 Commissural Neuron dissection <ol><li> Pincez le cerveau postérieur avec une pince. </li><li> Les neurones commissurales sont situés dans la partie la plus latérale de la moelle épinière (le côté dorsal). Découpez cette partie latérale avec un scalpel fin. </li></ol> Remarque: La partie dorsale de la moelle épinière peut être distinguée de la partie ventrale par la différence de cellule densité, la partie ventrale est plus opaque. Remarque: Pour couper les deux côtés avec la même qualité, commencer par la face rostrale et couper alternativement une petite longueur du côté droit et du côté gauche. <ol start="3"><li> Conserver le tissu disséqué en milieu Neurobasal sur la glace pour une utilisation immédiate. </li></ol> 5. Traitement des tissus Commissural avec le FP cm Remarque: Cette procédure ne nécessite pas de conditions stériles. Le tissu doit être prélevé dans les différents tubes de 1,5 ml. La gelée FP cm doit être utilisé qu&#39;une seule fois. Évitez regel multiples. Préparer chaud FP cm (37 ° C). 5.1 Traitements de neurones commissure <ol><li> Dilacerate la commissure tissu avec de petits ciseaux. </li></ol> Remarque: couper le tissu le plus petit possible, afin de potentialiser l&#39;accessibilité des cellules. <ol start="2"><li> Répartir équitablement le tissu entre les différents expérimental de traitement des conditions de contrôle et FP cm traitement. </li><li> Centrifuger les fragments de tissus à 800 x g pendant 1 min à 4 ° C. </li><li> Vérifiez la répartition entre les tubes. </li></ol> Remarque: Si nécessaire redistribuer et centrifuger à nouveau jusqu&#39;à ce que les fragments sont répartis de manière égale. <ol start="5"><li> Retirer le surnageant. </li><li> Ajouter les PF cm et de contrôle des traitements chauds pour les tissus. </li></ol> Remarque: le volume doit être ajustée à la quantité de la pastille et doit être au moins deux fois le volume du culot. <ol start="7"><li> Incuber à 37 ° C pendant 30 min. </li></ol> Remarque: Secouer doucement toutes les 10-15 min <ol start="8"><li> Centrifuger à 800 g pendant 1 min et retirez le traitement. </li><li> Ajouter le tampon de lyse </li></ol> Remarque: Le volume doit être ajusté à l&#39;unmontage de la pastille et doit être au moins deux fois le volume du culot. <ol start="10"><li> Introduire à la pipette de haut en bas pour remettre en suspension le culot. </li></ol> Remarque: un tourbillon peut également être utilisé. <ol start="11"><li> Incuber 15 min sur la glace. </li><li> Centrifuger à 14 000 g pendant 15 min à 4 ° C. </li><li> Gardez le surnageant et mesurer la quantité de protéine avec un dosage de Bradford 9. </li><li> Ajouter 6x Laemmli tampon. </li><li> Incuber à 95 ° C pendant 5 min pour dénaturer la teneur en protéines. </li></ol> Note: Les échantillons peuvent être utilisés immédiatement ou sont conservés à -80 ° C. <ol start="16"><li> Évaluer les effets du traitement par Western blot 10. </li></ol> Remarque: Au moins 50 pg de protéines totales devraient être chargés pour chaque voie.

<ol>
	<li>Nawabi, H., Castellani, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Axonal+commissures+in+the+central+nervous+system:+how+to+cross+the+midline.">Axonal commissures in the central nervous system: how to cross the midline.</a> Cell. Mol. Life Sci. 68, 2539-2553 (2011).</li><li>Placzek, M., Briscoe, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+floor+plate:+multiple+cells,+multiple+signals.">The floor plate: multiple cells, multiple signals.</a> Nat. Rev. Neurosci. 6, 230-240 (2005).</li><li>Chedotal, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Further+tales+of+the+midline.">Further tales of the midline.</a> Curr. Opin. Neurobiol. 21, 68-75 (1016).</li><li>Nawabi, 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=A+midline+switch+of+receptor+processing+regulates+commissural+axon+guidance+in+vertebrates.">A midline switch of receptor processing regulates commissural axon guidance in vertebrates.</a> Genes Dev. 24, 396-410 (2010).</li><li>Ruiz de Almodovar, 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=VEGF+mediates+commissural+axon+chemoattraction+through+its+receptor+Flk1.">VEGF mediates commissural axon chemoattraction through its receptor Flk1.</a> Neuron. 70, 966-978 (2011).</li><li>Charoy, 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=gdnf+activates+midline+repulsion+by+Semaphorin3B+via+NCAM+during+commissural+axon+guidance.">gdnf activates midline repulsion by Semaphorin3B via NCAM during commissural axon guidance.</a> Neuron. 75, 1051-1066 (2012).</li><li>Kiecker, C., Lumsden, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+organizers+in+patterning+the+nervous+system.">The role of organizers in patterning the nervous system.</a> Annu. Rev. Neurosci. 35, 347-367 (2012).</li><li>Le Dreau, G., Marti, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dorsal-ventral+patterning+of+the+neural+tube:+a+tale+of+three+signals.">Dorsal-ventral patterning of the neural tube: a tale of three signals.</a> Dev. Neurobiol. 72, 1471-1481 (2012).</li><li>Bradford, M. 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+rapid+and+sensitive+method+for+the+quantitation+of+microgram+quantities+of+protein+utilizing+the+principle+of+protein-dye+binding.">A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding.</a> Anal. Biochem. 72, 248-254 (1976).</li><li>Eslami, A., Lujan, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Western+blotting:+sample+preparation+to+detection.">Western blotting: sample preparation to detection.</a> J. Vis. Exp. , (2010).</li><li>Salinas, P. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+morphogen+sonic+hedgehog+collaborates+with+netrin-1+to+guide+axons+in+the+spinal+cord.">The morphogen sonic hedgehog collaborates with netrin-1 to guide axons in the spinal cord.</a> Trends Neurosci. 26, 641-643 (2003).</li><li>Bechara, 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=FAK-MAPK-dependent+adhesion+disassembly+downstream+of+L1+contributes+to+semaphorin3A-induced+collapse.">FAK-MAPK-dependent adhesion disassembly downstream of L1 contributes to semaphorin3A-induced collapse.</a> EMBO J. 27, 1549-1562 (2008).</li></ol>

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La production de plaque de sol milieu conditionné fournit un moyen simple et efficace pour évaluer les propriétés biologiques des signaux libérés de la plaque de sol. La matrice de plasma-thrombine offre une excellente condition de la survie de tissu. Néanmoins, cet environnement enrichi pourrait être une limitation pour certains types d&#39;expériences. Ainsi, le tissu de la plaque de fond peut également être cultivé dans une matrice d&#39;agarose. La qualité de la plaque de so...

La plaque de sol est un centre de formation de motif bien connu de la moelle épinière en développement, jouent un rôle clé dans la spécification des progéniteurs et les lignées de cellules post-mitotiques et contrôler la navigation des axones 7,8. La procédure expérimentale décrite ici pour produire FP cm permet aux enquêteurs d&#39;évaluer les propriétés fonctionnelles des signaux de plaque dérivé étage dans un des contextes différents des processus de développement, de la structuration et la survie cellulaire à cellulaire et la migration des axones. Pour illustrer l&#39;utilisation de tels FP cm, les tissus de la moelle épinière dorsale contenant des neurones commissurales sont disséqués, dilacérées et stimulées avec du FP cm. Les tissus peuvent ensuite être traitées pour l&#39;analyse Western blot. Cela permet d&#39;instruction des règlements de la machine de guidage axonal par des signaux libérés plancher plat. Procédé de traitement de tissu frais dilacérées maintient le grand avantage de conserver le micro-environnement des cellules au sein de ee tissu. Ainsi, les conséquences du traitement par FP cm ou n&#39;importe quels types de traitement sont évaluées de façon plus physiologique que dans des conditions de culture cellulaire et tissulaire.

<table border="1">
	<tbody>
		<tr>
			<td>Name of Reagent/Material</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td>REAGENTS REQUIRED</td>
		</tr>
		<tr>
			<td>PBS</td>
			<td>Invitrogen</td>
			<td>14190-094</td>
			<td></td>
		</tr>
		<tr>
			<td>HBSS, Ca2+/Mg2+- free</td>
			<td>Invitrogen</td>
			<td>14170-088</td>
			<td></td>
		</tr>
		<tr>
			<td>Glucose</td>
			<td>Sigma</td>
			<td>G-7021</td>
			<td></td>
		</tr>
		<tr>
			<td>Neurobasal</td>
			<td>Invitrogen</td>
			<td>21103-049</td>
			<td></td>
		</tr>
		<tr>
			<td>Plasma</td>
			<td>Sigma</td>
			<td>P-3266</td>
			<td>1mg/ml (Reconstitute in H2O and filtrate)</td>
		</tr>
		<tr>
			<td>Thrombin</td>
			<td>Sigma</td>
			<td>T-4648</td>
			<td>10mg/ml(Reconstitute in H2O and filtrate)</td>
		</tr>
		<tr>
			<td>B27</td>
			<td>Invitrogen</td>
			<td>17504-044</td>
			<td>50X</td>
		</tr>
		<tr>
			<td>Hepes (260g/mol)</td>
			<td>Sigma</td>
			<td>H-7006</td>
			<td></td>
		</tr>
		<tr>
			<td>EDTA</td>
			<td>Sigma</td>
			<td>E-5513</td>
			<td>0,5M pH8</td>
		</tr>
		<tr>
			<td>MgCL2</td>
			<td>Euromedex</td>
			<td>2189</td>
			<td>1M</td>
		</tr>
		<tr>
			<td>Glycerol</td>
			<td>VWR</td>
			<td>24388.295</td>
			<td></td>
		</tr>
		<tr>
			<td>IGEPAL</td>
			<td>Sigma</td>
			<td>I-3021</td>
			<td></td>
		</tr>
		<tr>
			<td>Complete Protease inhibitor Cocktail Tablets</td>
			<td>Roche</td>
			<td>04 693 116 001</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Orthovanadate (Na3VO4)</td>
			<td>Sigma</td>
			<td>S-6508</td>
			<td></td>
		</tr>
		<tr>
			<td>distilled H2O</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td>Table 1. Reagents required</td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td>TOOLS AND MATERIAL</td>
		</tr>
		<tr>
			<td>Surgical scissors</td>
			<td>Fine Science Tools</td>
			<td>14002-12</td>
			<td></td>
		</tr>
		<tr>
			<td>Adson forceps</td>
			<td>Fine Science Tools</td>
			<td>11027-12</td>
			<td></td>
		</tr>
		<tr>
			<td>Dumont #5 Fine Tips forceps</td>
			<td>Fine Science Tools</td>
			<td>11254-20</td>
			<td></td>
		</tr>
		<tr>
			<td>micro knives</td>
			<td>Fine Science Tools</td>
			<td>10136-14</td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td>Table 2. Tools and material</td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td>
			<table border="1">
				<tbody>
					<tr>
						<td colspan="2">Dissection and FP culture</td>
					</tr>
					<tr>
						<td>Ethanol 70%</td>
						<td></td>
					</tr>
					<tr>
						<td>dissection hood</td>
						<td></td>
					</tr>
					<tr>
						<td>dissection microscope</td>
						<td></td>
					</tr>
					<tr>
						<td>Petri dishes</td>
						<td></td>
					</tr>
					<tr>
						<td>glass coverslips</td>
						<td>18mm x 18mm</td>
					</tr>
					<tr>
						<td>Bunsen gas burner</td>
						<td></td>
					</tr>
					<tr>
						<td>24 well plate</td>
						<td></td>
					</tr>
					<tr>
						<td>tissue culture incubator (37&#176;C, 5% CO2, humidity controlled)</td>
						<td></td>
					</tr>
					<tr>
						<td>Centrifuge</td>
						<td></td>
					</tr>
					<tr>
						<td colspan="2">RECIPES</td>
					</tr>
					<tr>
						<td colspan="2">FP culture media</td>
					</tr>
					<tr>
						<td>Neurobasal</td>
						<td></td>
					</tr>
					<tr>
						<td>B27</td>
						<td>1/50e dilution from stock</td>
					</tr>
					<tr>
						<td colspan="2">HBSS - Thrombin</td>
					</tr>
					<tr>
						<td>HBSS</td>
						<td>1 ml</td>
					</tr>
					<tr>
						<td>Thrombin 10mg/ml</td>
						<td>30 &#956;l</td>
					</tr>
					<tr>
						<td colspan="2">Lysis Buffer pH7,4</td>
					</tr>
					<tr>
						<td>Hepes (260 g/mol)</td>
						<td>25mM</td>
					</tr>
					<tr>
						<td>EDTA (pH8)</td>
						<td>5mM</td>
					</tr>
					<tr>
						<td>MgCL2</td>
						<td>1mM</td>
					</tr>
					<tr>
						<td>Glycerol</td>
						<td>10%</td>
					</tr>
					<tr>
						<td>IGEPAL (NP40)</td>
						<td>0.10%</td>
					</tr>
					<tr>
						<td>Protease Inhibitor Cocktail</td>
						<td>1X</td>
					</tr>
					<tr>
						<td>Sodium Orthovanadate</td>
						<td>0,2M</td>
					</tr>
					<tr>
						<td>H2O</td>
						<td></td>
					</tr>
					<tr>
						<td colspan="2">Laemmli Buffer</td>
					</tr>
					<tr>
						<td>Tris 0,5M, pH 6,8</td>
						<td>375 mM</td>
					</tr>
					<tr>
						<td>SDS</td>
						<td>6%</td>
					</tr>
					<tr>
						<td>Glycerol</td>
						<td>60%</td>
					</tr>
					<tr>
						<td>DTT</td>
						<td>0,6M</td>
					</tr>
					<tr>
						<td>Bromophenol blue</td>
						<td></td>
					</tr>
					<tr>
						<td>H2O</td>
						<td></td>
					</tr>
				</tbody>
			</table>
			</td>
		</tr>
	</tbody>
</table>

culture of isolated floor plate tissue and production of conditioned medium to assess functional properties of floor plate-released signals

Au cours du développement, les progéniteurs et les neurones post-mitotiques reçoivent des signaux de territoires adjacents qui régulent leur sort. La plaque de sol est un groupe de cellules gliales tapissant le canal épendymaire en position ventrale. La plaque de sol exprime morphogènes clés contribuant à la structuration de lignées de cellules dans la moelle épinière. À des stades de développement plus tard, la plaque de sol réglemente la navigation des axones de la moelle épinière, agissant comme une barrière pour empêcher le passage des axones homolatéraux et franchissement de la ligne médiane de contrôle par les axones commissure 1. Ces fonctions sont réalisées grâce à la sécrétion de diverses signaux de guidage. Certains de ces indices agir comme attractifs et répulsifs pour les axones en croissance tandis que d&#39;autres réglementent les récepteurs d&#39;orientation et de signalisation en aval de moduler la sensibilité des axones aux 2,3 signaux de guidage locales. Nous décrivons ici une méthode qui permet l&#39;étude des propriétés des signaux provenant du sol plaque dans une variété de dévecontextes lopmental, sur la base de la production de support de plancher Plate conditionné (FP cm) 4-6. Nous illustrons ensuite l&#39;utilisation de ce FP cm dans le cadre de guidage axonal. Tout d&#39;abord, la moelle épinière est isolé à partir d&#39;embryons de souris à E12.5 et de la plaque de fond est disséqué et cultivées dans une matrice plasma-thrombine (figure 1). Deuxième deux jours plus tard, le tissu commissure sont disséqués à partir d&#39;embryons E12.5, trituré et exposé à la FP cm. Troisièmement, le tissu est traité pour analyse par Western blot de marqueurs commissure.

Commissurales tissus ont été traités par le FP cm et les échantillons ont été traités pour l&#39;analyse des niveaux des récepteurs de Western blot. Application de la FP cm a été montré pour augmenter les niveaux d&#39;un récepteur d&#39;orientation, PlexinA1, qui médiatise la sensibilité des axones commissure de la ligne médiane répulsif Semaphorin3B après avoir traversé (Figure 2). Cette étude a révélé que les signaux libérés par la FP régulent les niveau...

Watch this Scientific Journal Video about Culture of Isolated Floor Plate Tissue and Production of Conditioned Medium to Assess Functional Properties of Floor Plate-released Signals at JoVE.com

Culture of Isolated Floor Plate Tissue and Production of Conditioned Medium to Assess Functional Properties of Floor Plate-released Signals

Le plancher est une structure essentielle des neurones de la moelle épinière en développement, fournissant des signaux diffusibles de progéniteurs et la différenciation. Nous décrivons une méthode pour produire des varangues milieu conditionné, à appliquer au tissu de la moelle épinière frais, et d&#39;évaluer les conséquences sur les protéines d&#39;intérêt par la biochimie.

Culture de tissus isolement de la plaque au sol et la production de milieu conditionné à évaluer les propriétés fonctionnelles des signaux plancher Plate-publié

During development, progenitors and post-mitotic neurons receive signals from adjacent territories that regulate their fate. The floor-plate is a group of ...

culture-isolated-floor-plate-tissue-production-conditioned-medium-to

Research

JoVE Journal

Neuroscience

7.9K vues.  University of Lyon 1.  Le plancher est une structure essentielle des neurones de la moelle épinière en développement, fournissant des signaux diffusibles de progéniteurs et la différenciation. Nous décrivons une méthode pour produire des varangues milieu conditionné, à appliquer au tissu de la moelle épinière frais, et d'évaluer les conséquences sur les protéines d'intérêt par la biochimie. 

Vidéo: Culture of Isolated Floor Plate Tissue and Production of Conditioned Medium to Assess Functional Properties of Floor Plate-released Signals

A Functional Motor Unit in the Culture Dish: Co-culture of Spinal Cord Explants and Muscle Cells

Human primary muscle cells cultured aneurally in monolayer rarely contract spontaneously because, in the absence of a nerve component, cell differentiation is limited and motor neuron stimulation is missing1. These limitations hamper the in vitro study of many neuromuscular diseases in cultured muscle cells. Importantly, the experimental constraints of monolayered, cultured muscle cells can be overcome by functional innervation of myofibers with spinal cord explants in co-cultures.
Here, we show the different steps required to achieve an efficient, proper innervation of human primary muscle cells, leading to complete differentiation and fiber contraction according to the method developed by Askanas2. To do so, muscle cells are co-cultured with spinal cord explants of rat embryos at ED 13.5, with the dorsal root ganglia still attached to the spinal cord slices. After a few days, the muscle fibers start to contract and eventually become cross-striated through innervation by functional neurites projecting from the spinal cord explants that connecting to the muscle cells. This structure can be maintained for many months, simply by regular exchange of the culture medium.
The applications of this invaluable tool are numerous, as it represents a functional model for multidisciplinary analyses of human muscle development and innervation. In fact, a complete de novo neuromuscular junction installation occurs in a culture dish, allowing an easy measurement of many parameters at each step, in a fundamental and physiological context.
Just to cite a few examples, genomic and/or proteomic studies can be performed directly on the co-cultures. Furthermore, pre- and post-synaptic effects can be specifically and separately assessed at the neuromuscular junction, because both components come from different species, rat and human, respectively. The nerve-muscle co-culture can also be performed with human muscle cells isolated from patients suffering from muscle or neuromuscular diseases3, and thus can be used as a screening tool for candidate drugs. Finally, no special equipment but a regular BSL2 facility is needed to reproduce a functional motor unit in a culture dish. This method thus is valuable for both the muscle as well as the neuromuscular research communities for physiological and mechanistic studies of neuromuscular function, in a normal and disease context.

Cultured muscle cells are an inadequate model to recapitulate innervated muscle in vivo. A functional motor unit can be reproduced in vitro by innervation of differentiated human primary muscle cells using rat embryo spinal cord explants. This article describes how co-cultures of spinal cord explants and muscle cells are established.

Une unité fonctionnelle du moteur dans la boîte de culture: La co-culture d&#39;explants de la moelle épinière et les cellules musculaires

Human primary muscle cells cultured  aneurally in monolayer rarely contract spontaneously because, in the absence of  a nerve component, cell ...

Recherche

Neurosciences

Recording Human Electrocorticographic (ECoG) Signals for Neuroscientific Research and Real-time Functional Cortical Mapping

Neuroimaging studies of human cognitive, sensory, and motor processes are usually based on noninvasive techniques such as electroencephalography (EEG), magnetoencephalography or functional magnetic-resonance imaging. These techniques have either inherently low temporal or low spatial resolution, and suffer from low signal-to-noise ratio and/or poor high-frequency sensitivity. Thus, they are suboptimal for exploring the short-lived spatio-temporal dynamics of many of the underlying brain processes. In contrast, the invasive technique of electrocorticography (ECoG) provides brain signals that have an exceptionally high signal-to-noise ratio, less susceptibility to artifacts than EEG, and a high spatial and temporal resolution (i.e., &lt;1 cm/&lt;1 millisecond, respectively). ECoG involves measurement of electrical brain signals using electrodes that are implanted subdurally on the surface of the brain. Recent studies have shown that ECoG amplitudes in certain frequency bands carry substantial information about task-related activity, such as motor execution and planning1, auditory processing2 and visual-spatial attention3. Most of this information is captured in the high gamma range (around 70-110 Hz). Thus, gamma activity has been proposed as a robust and general indicator of local cortical function1-5. ECoG can also reveal functional connectivity and resolve finer task-related spatial-temporal dynamics, thereby advancing our understanding of large-scale cortical processes. It has especially proven useful for advancing brain-computer interfacing (BCI) technology for decoding a user's intentions to enhance or improve communication6 and control7. Nevertheless, human ECoG data are often hard to obtain because of the risks and limitations of the invasive procedures involved, and the need to record within the constraints of clinical settings. Still, clinical monitoring to localize epileptic foci offers a unique and valuable opportunity to collect human ECoG data. We describe our methods for collecting recording ECoG, and demonstrate how to use these signals for important real-time applications such as clinical mapping and brain-computer interfacing. Our example uses the BCI2000 software platform8,9 and the SIGFRIED10 method, an application for real-time mapping of brain functions. This procedure yields information that clinicians can subsequently use to guide the complex and laborious process of functional mapping by electrical stimulation.
Prerequisites and Planning:
Patients with drug-resistant partial epilepsy may be candidates for resective surgery of an epileptic focus to minimize the frequency of seizures. Prior to resection, the patients undergo monitoring using subdural electrodes for two purposes: first, to localize the epileptic focus, and second, to identify nearby critical brain areas (i.e., eloquent cortex) where resection could result in long-term functional deficits. To implant electrodes, a craniotomy is performed to open the skull. Then, electrode grids and/or strips are placed on the cortex, usually beneath the dura. A typical grid has a set of 8 x 8 platinum-iridium electrodes of 4 mm diameter (2.3 mm exposed surface) embedded in silicon with an inter-electrode distance of 1cm. A strip typically contains 4 or 6 such electrodes in a single line. The locations for these grids/strips are planned by a team of neurologists and neurosurgeons, and are based on previous EEG monitoring, on a structural MRI of the patient's brain, and on relevant factors of the patient's history. Continuous recording over a period of 5-12 days serves to localize epileptic foci, and electrical stimulation via the implanted electrodes allows clinicians to map eloquent cortex. At the end of the monitoring period, explantation of the electrodes and therapeutic resection are performed together in one procedure.
In addition to its primary clinical purpose, invasive monitoring also provides a unique opportunity to acquire human ECoG data for neuroscientific research. The decision to include a prospective patient in the research is based on the planned location of their electrodes, on the patient's performance scores on neuropsychological assessments, and on their informed consent, which is predicated on their understanding that participation in research is optional and is not related to their treatment. As with all research involving human subjects, the research protocol must be approved by the hospital's institutional review board. The decision to perform individual experimental tasks is made day-by-day, and is contingent on the patient's endurance and willingness to participate. Some or all of the experiments may be prevented by problems with the clinical state of the patient, such as post-operative facial swelling, temporary aphasia, frequent seizures, post-ictal fatigue and confusion, and more general pain or discomfort.
At the Epilepsy Monitoring Unit at Albany Medical Center in Albany, New York, clinical monitoring is implemented around the clock using a 192-channel Nihon-Kohden Neurofax monitoring system. Research recordings are made in collaboration with the Wadsworth Center of the New York State Department of Health in Albany. Signals from the ECoG electrodes are fed simultaneously to the research and the clinical systems via splitter connectors. To ensure that the clinical and research systems do not interfere with each other, the two systems typically use separate grounds. In fact, an epidural strip of electrodes is sometimes implanted to provide a ground for the clinical system. Whether research or clinical recording system, the grounding electrode is chosen to be distant from the predicted epileptic focus and from cortical areas of interest for the research. Our research system consists of eight synchronized 16-channel g.USBamp amplifier/digitizer units (g.tec, Graz, Austria). These were chosen because they are safety-rated and FDA-approved for invasive recordings, they have a very low noise-floor in the high-frequency range in which the signals of interest are found, and they come with an SDK that allows them to be integrated with custom-written research software. In order to capture the high-gamma signal accurately, we acquire signals at 1200Hz sampling rate-considerably higher than that of the typical EEG experiment or that of many clinical monitoring systems. A built-in low-pass filter automatically prevents aliasing of signals higher than the digitizer can capture. The patient's eye gaze is tracked using a monitor with a built-in Tobii T-60 eye-tracking system (Tobii Tech., Stockholm, Sweden). Additional accessories such as joystick, bluetooth Wiimote (Nintendo Co.), data-glove (5th Dimension Technologies), keyboard, microphone, headphones, or video camera are connected depending on the requirements of the particular experiment.
Data collection, stimulus presentation, synchronization with the different input/output accessories, and real-time analysis and visualization are accomplished using our BCI2000 software8,9. BCI2000 is a freely available general-purpose software system for real-time biosignal data acquisition, processing and feedback. It includes an array of pre-built modules that can be flexibly configured for many different purposes, and that can be extended by researchers' own code in C++, MATLAB or Python. BCI2000 consists of four modules that communicate with each other via a network-capable protocol: a Source module that handles the acquisition of brain signals from one of 19 different hardware systems from different manufacturers; a Signal Processing module that extracts relevant ECoG features and translates them into output signals; an Application module that delivers stimuli and feedback to the subject; and the Operator module that provides a graphical interface to the investigator.
A number of different experiments may be conducted with any given patient. The priority of experiments will be determined by the location of the particular patient's electrodes. However, we usually begin our experimentation using the SIGFRIED (SIGnal modeling For Realtime Identification and Event Detection) mapping method, which detects and displays significant task-related activity in real time. The resulting functional map allows us to further tailor subsequent experimental protocols and may also prove as a useful starting point for traditional mapping by electrocortical stimulation (ECS).
Although ECS mapping remains the gold standard for predicting the clinical outcome of resection, the process of ECS mapping is time consuming and also has other problems, such as after-discharges or seizures. Thus, a passive functional mapping technique may prove valuable in providing an initial estimate of the locus of eloquent cortex, which may then be confirmed and refined by ECS. The results from our passive SIGFRIED mapping technique have been shown to exhibit substantial concurrence with the results derived using ECS mapping10.
The protocol described in this paper establishes a general methodology for gathering human ECoG data, before proceeding to illustrate how experiments can be initiated using the BCI2000 software platform. Finally, as a specific example, we describe how to perform passive functional mapping using the BCI2000-based SIGFRIED system.

Recording Human Electrocorticographic ECoG Signals for Neuroscientific Research and Real-time Functional Cortical Mapping

We present a method for collecting electrocorticographic signals for research purposes from humans who are undergoing invasive epilepsy monitoring. We show how to use the BCI2000 software platform for data collection, signal processing and stimulus presentation. Specifically, we demonstrate SIGFRIED, a BCI2000-based tool for real-time functional brain mapping.

Enregistrement de l&#39;homme (Electrocorticographic ECoG) Signaux pour la recherche neuroscientifique et en temps réel la cartographie fonctionnelle corticale

Neuroimaging studies of human cognitive, sensory, and motor processes are usually based on noninvasive techniques such as electroencephalography (EEG), ...

Dissection, Culture, and Analysis of Xenopus laevis Embryonic Retinal Tissue

The process by which the anterior region of the neural plate gives rise to the vertebrate retina continues to be a major focus of both clinical and basic research. In addition to the obvious medical relevance for understanding and treating retinal disease, the development of the vertebrate retina continues to serve as an important and elegant model system for understanding neuronal cell type determination and differentiation1-16. The neural retina consists of six discrete cell types (ganglion, amacrine, horizontal, photoreceptors, bipolar cells, and M&uuml;ller glial cells) arranged in stereotypical layers, a pattern that is largely conserved among all vertebrates 12,14-18.
While studying the retina in the intact developing embryo is clearly required for understanding how this complex organ develops from a protrusion of the forebrain into a layered structure, there are many questions that benefit from employing approaches using primary cell culture of presumptive retinal cells 7,19-23. For example, analyzing cells from tissues removed and dissociated at different stages allows one to discern the state of specification of individual cells at different developmental stages, that is, the fate of the cells in the absence of interactions with neighboring tissues 8,19-22,24-33. Primary cell culture also allows the investigator to treat the culture with specific reagents and analyze the results on a single cell level 5,8,21,24,27-30,33-39. Xenopus laevis, a classic model system for the study of early neural development 19,27,29,31-32,40-42, serves as a particularly suitable system for retinal primary cell culture 10,38,43-45.
Presumptive retinal tissue is accessible from the earliest stages of development, immediately following neural induction 25,38,43. In addition, given that each cell in the embryo contains a supply of yolk, retinal cells can be cultured in a very simple defined media consisting of a buffered salt solution, thus removing the confounding effects of incubation or other sera-based products 10,24,44-45.
However, the isolation of the retinal tissue from surrounding tissues and the subsequent processing is challenging. Here, we present a method for the dissection and dissociation of retinal cells in Xenopus laevis that will be used to prepare primary cell cultures that will, in turn, be analyzed for calcium activity and gene expression at the resolution of single cells. While the topic presented in this paper is the analysis of spontaneous calcium transients, the technique is broadly applicable to a wide array of research questions and approaches (Figure 1).

Dissection, Culture, and Analysis of Xenopus laevis Embryonic Retinal Tissue

Xenopus laevis provides an ideal model system for studying cell fate specification and physiological function of individual retinal cells in primary cell culture. Here we present a technique for dissecting retinal tissues and generating primary cell cultures that are imaged for calcium activity and analyzed by in situ hybridization.

Dissection, de la culture, et de l&#39;analyse des<em&gt; Xenopus laevis</em&gt; Tissus embryonnaires rétine

The process by which  the anterior region of the neural plate gives rise to the vertebrate retina  continues to be a major focus of both clinical and ...

Use of pHluorin to Assess the Dynamics of Axon Guidance Receptors in Cell Culture and in the Chick Embryo

During development, axon guidance receptors play a crucial role in regulating axons sensitivity to both attractive and repulsive cues. Indeed, activation of the guidance receptors is the first step of the signaling mechanisms allowing axon tips, the growth cones, to respond to the ligands. As such, the modulation of their availability at the cell surface is one of the mechanisms that participate in setting the growth cone sensitivity. We describe here a method to precisely visualize the spatio-temporal cell surface dynamics of an axon guidance receptor both in vitro and in vivo in the developing chick spinal cord. We took advantage of the pH-dependent fluorescence property of a green fluorescent protein (GFP) variant to specifically detect the fraction of the axon guidance receptor that is addressed to the plasma membrane. We first describe the in vitro validation of such pH-dependent constructs and we further detail their use in vivo, in the chick spinal chord, to assess the spatio-temporal dynamics of the axon guidance receptor of interest.

We describe here the use of a pH-sensitive green fluorescent protein variant, pHluorin, to study the spatio-temporal dynamics of axon guidance receptors trafficking at the cell surface.&#160;The pHluorin-tagged receptor is expressed both in cell culture and in vivo, using electroporation of the chick embryo.

Utilisation de la pHluorine pour évaluer la dynamique des récepteurs de guidage axonaux dans la culture cellulaire et dans l’embryon de poussin

During development, axon guidance receptors play a crucial role in regulating axons sensitivity to both attractive and repulsive cues. Indeed, activation ...

Closed-loop Neuro-robotic Experiments to Test Computational Properties of Neuronal Networks

Information coding in the Central Nervous System (CNS) remains unexplored. There is mounting evidence that, even at a very low level, the representation of a given stimulus might be dependent on context and history. If this is actually the case, bi-directional interactions between the brain (or if need be a reduced model of it) and sensory-motor system can shed a light on how encoding and decoding of information is performed. Here an experimental system is introduced and described in which the activity of a neuronal element (i.e., a network of neurons extracted from embryonic mammalian hippocampi) is given context and used to control the movement of an artificial agent, while environmental information is fed back to the culture as a sequence of electrical stimuli. This architecture allows a quick selection of diverse encoding, decoding, and learning algorithms to test different hypotheses on the computational properties of neuronal networks.

In this paper, an experimental framework to perform closed-loop experiments is presented, in which information processing (i.e., coding and decoding) and learning of neuronal assemblies are studied during the continuous interaction with a robotic body.

En boucle fermée expériences neuro-robotique l&#39;analyse des propriétés de calcul de réseaux neuronaux

Information coding in the Central Nervous System (CNS) remains unexplored. There is mounting evidence that, even at a very low level, the representation ...

Double-barreled and Concentric Microelectrodes for Measurement of Extracellular Ion Signals in Brain Tissue

Electrical activity in the brain is accompanied by significant ion fluxes across membranes, resulting in complex changes in the extracellular concentration of all major ions. As these ion shifts bear significant functional consequences, their quantitative determination is often required to understand the function and dysfunction of neural networks under physiological and pathophysiological conditions. In the present study, we demonstrate the fabrication and calibration of double-barreled ion-selective microelectrodes, which have proven to be excellent tools for such measurements in brain tissue. Moreover, so-called &#8220;concentric&#8221; ion-selective microelectrodes are also described, which, based on their different design, offer a far better temporal resolution of fast ion changes. We then show how these electrodes can be employed in acute brain slice preparations of the mouse hippocampus. Using double-barreled, potassium-selective microelectrodes, changes in the extracellular potassium concentration ([K+]o) in response to exogenous application of glutamate receptor agonists or during epileptiform activity are demonstrated. Furthermore, we illustrate the response characteristics of sodium-sensitive, double-barreled and concentric electrodes and compare their detection of changes in the extracellular sodium concentration ([Na+]o) evoked by bath or pressure application of drugs. These measurements show that while response amplitudes are similar, the concentric sodium microelectrodes display a superior signal-to-noise ratio and response time as compared to the double-barreled design. Generally, the demonstrated procedures will be easily transferable to measurement of other ions species, including pH or calcium, and will also be applicable to other preparations.

We demonstrate the fabrication, calibration and properties of two types of ion-selective microelectrodes (double-barreled and concentric) for measurement of ion concentrations in brain tissue. These are then used in the mouse hippocampal slice preparation to show that excitatory activity changes both extracellular potassium and sodium concentrations.

Microélectrodes à double canon et concentrique pour la mesure de signaux extracellulaires Ion dans le tissu cérébral

Electrical activity in the brain is accompanied by significant ion fluxes across membranes, resulting in complex changes in the extracellular ...

Characterizing Multiscale Mechanical Properties of Brain Tissue Using Atomic Force Microscopy, Impact Indentation, and Rheometry

To design and engineer materials inspired by the properties of the brain, whether for mechanical simulants or for tissue regeneration studies, the brain tissue itself must be well characterized at various length and time scales. Like many biological tissues, brain tissue exhibits a complex, hierarchical structure. However, in contrast to most other tissues, brain is of very low mechanical stiffness, with Young&#39;s elastic moduli E on the order of 100s of Pa. This low stiffness can present challenges to experimental characterization of key mechanical properties. Here, we demonstrate several mechanical characterization techniques that have been adapted to measure the elastic and viscoelastic properties of hydrated, compliant biological materials such as brain tissue, at different length scales and loading rates. At the microscale, we conduct creep-compliance and force relaxation experiments using atomic force microscope-enabled indentation. At the mesoscale, we perform impact indentation experiments using a pendulum-based instrumented indenter. At the macroscale, we conduct parallel plate rheometry to quantify the frequency dependent shear elastic moduli. We also discuss the challenges and limitations associated with each method. Together these techniques enable an in-depth mechanical characterization of brain tissue that can be used to better understand the structure of brain and to engineer bio-inspired materials.

We present a set of techniques to characterize the viscoelastic mechanical properties of brain at the micro-, meso-, and macro-scales.

Caractériser Propriétés Multiscale mécaniques des tissus de cerveau en utilisant la microscopie à force atomique, Impact indentation et Rheometry

To design and engineer materials inspired by the properties of the brain, whether for mechanical simulants or for tissue regeneration studies, the brain ...

Isolation and Culture of Rodent Microglia to Promote a Dynamic Ramified Morphology in Serum-free Medium

Microglia represent 5 - 10% of all central nervous system (CNS) cells and are increasingly drawing attention due to their contributions during development, homeostasis, and disease. Although macrophages have been studied in detail for decades, specialized features of microglia, the tissue-resident macrophages of the CNS, have remained largely mysterious, in part due to limitations in the ability to recapitulate mature microglial properties in culture. Here, we illustrate a straightforward procedure for the rapid isolation of pure microglia from the mature rodent brain. We also describe serum-free culture conditions that support high levels of microglial viability over time. Microglia cultured under these defined-medium conditions exhibit elaborate ramified processes and dynamic surveillance behavior. We illustrate some effects of serum exposure on cultured microglia and discuss how these serum-free cultures compare to both serum-exposed cultures as well as microglia in vivo.

Efforts to understand microglial function in detail have been hindered by the lack of microglial culture models that recapitulate the properties of mature in vivo microglia. This protocol describes an isolation and culture approach designed to maintain robust survival of highly ramified mature rat microglia under defined-medium conditions.

Isolement et Culture des microglies rongeurs pour promouvoir une dynamique ramifié morphologie dans un milieu sans sérum

Microglia represent 5 - 10% of all central nervous system (CNS) cells and are increasingly drawing attention due to their contributions during ...

Presynapse Formation Assay Using Presynapse Organizer Beads and &ldquo;Neuron Ball&rdquo; Culture

During neuronal development, synapse formation is an important step to establish neural circuits. To form synapses, synaptic proteins must be supplied in appropriate order by transport from cell bodies and/or local translation in immature synapses. However, it is not fully understood how synaptic proteins accumulate in synapses in proper order. Here, we present a novel method to analyze presynaptic formation by using the combination of neuron ball culture with beads to induce presynapse formation. Neuron balls that is neuronal cell aggregates provide axonal sheets far from cell bodies and dendrites, so that weak fluorescent signals of presynapses can be detected by avoiding overwhelming signals of cell bodies. As beads to trigger presynapse formation, we use beads conjugated with leucine-rich repeat transmembrane neuronal 2 (LRRTM2), an excitatory presynaptic organizer. Using this method, we demonstrated that vesicular glutamate transporter 1 (vGlut1), a synaptic vesicle protein, accumulated in presynapses faster than Munc18-1, an active zone protein. Munc18-1 accumulated translation-dependently in presynapse even after removing cell bodies. This finding indicates the Munc18-1 accumulation by local translation in axons, not transport from cell bodies. In conclusion, this method is suitable to analyze accumulation of synaptic proteins in presynapses and source of synaptic proteins. As neuron ball culture is simple and it is not necessary to use special apparatus, this method could be applicable to other experimental platforms.

Presynapse formation is a dynamic process including accumulation of synaptic proteins in proper order. In this method, presynapse formation is triggered by beads conjugated with a presynapse organizer protein on axonal sheets of &#8220;neuron ball&#8221; culture, so that accumulation of synaptic proteins is easy to be analyzed during presynapse formation.

Presynapse Formation Assay Using Presynapse Organizer Beads and "Neuron Ball" Culture

During neuronal development, synapse formation is an important step to establish neural circuits. To form synapses, synaptic proteins must be supplied in ...

Primary Culture of Neurons Isolated from Embryonic Mouse Cerebellum

The use of primary cell cultures has become one of the major tools to study the nervous system in vitro. The ultimate goal of using this simplified model system is to provide a controlled microenvironment and maintain the high survival rate and the natural features of dissociated neuronal and nonneuronal cells as much as possible under in vitro conditions. In this article, we demonstrate a method of isolating primary neurons from the developing mouse cerebellum, placing them in an in vitro environment, establishing their growth, and monitoring their viability and differentiation for several weeks. This method is applicable to embryonic neurons dissociated from cerebellum between embryonic days 12&ndash;18.

Conducting in vitro experiments to reflect in vivo conditions as adequately as possible is not an easy task. The use of primary cell cultures is an important step toward understanding cell biology in a whole organism. The provided protocol outlines how to successfully grow and culture embryonic mouse cerebellar neurons.

Culture primaire des neurones isolés du cervelet de souris embryonnaire

The use of primary cell cultures has become one of the major tools to study the nervous system in vitro. The ultimate goal of using this simplified model ...