Die Autoren erkennen an der Clemson University Creative Inquiry Programm und NSF CBET1254609 für die Finanzierung für dieses Projekt.

1. Die Herstellung eines Mikrokanal-Kammer einen Konzentrationsgradienten erstellen <ol><li> Schneiden eines Acrylformteil <ol><li> Besorgen Sie sich ein Stück Acryl mit der gewünschten Breite. Normalerweise verwenden Sie 1/16-Zoll-dicke Acrylplatten. Dickere Platten sind schwierig, gut und sehr dünne Bleche zu schneiden die erforderliche mechanische Festigkeit nicht haben, so dass sie während des Prozesses zu brechen oder sich verziehen. </li><li> Erstellen eines CAD-Datei mit der gewünschten Form des Acrylstück einen Hohlraum innerhalb des Polydimethylsiloxans (PDMS) zu erzeugen. Stellen Sie die Kanalbreite und Länge des gewünschten Gradienten relevant für einzelne experimentelle Protokolle zu erreichen. <ol><li> Hier verwenden ein Acryl Stück der folgenden Dimensionen: zwei Quadrate (0,254 cm x 0,254 cm) verbunden mit einem 0,127 cm breiten Kanal (0,254 cm lang) (Abbildung 1). </li></ol></li><li> Importieren Sie die CAD-Datei in die Laserschneidvorrichtung und legen Sie die Acryl-Stück in einem Laserschneider nach dem manulers Protokoll. HINWEIS: Alternativ 3D-Druck, das Stück aus der CAD-Konstruktion. Der Vorteil dieses Verfahrens besteht darin, dass alternative Materialien für die Form verwendet werden kann; kann jedoch die Auflösung und die Reproduzierbarkeit, mit 3D-Druck verringert werden im Vergleich zum Laserschneiden. </li></ol></li></ol><img alt="Abbildung 1" src="/files/ftp_upload/55264/55264fig1.jpg" /> Abbildung 1: Computer-Aided Design (CAD) Darstellung von Microchannel- Kammer. Dieses Bild zeigt die CAD-Zeichnung des Acryleinsatz erforderlich, um die Mikrokanalkammer zu erzeugen. 1 A) Draufsicht der CAD - Zeichnung, 1B) Seitenansicht der CAD - Zeichnung mit Abmessungen in Zoll, 1C) Draufsicht einer CAD - Zeichnung mit Abmessungen in Zoll <a href="http://ecsource.jove.com/files/ftp_upload/55264/55264fig1large.jpg" target="_blank">Bitte klicken Sie hier eine größere Version dieser Figur zu sehen.</a> <ol start="2"><li&gt; Gießen des Polydimethylsiloxans (PDMS) <ol><li> In einem Boot wiegen, mischen 10 Gewichtsteile der kommerziellen Elastomerbasis (zB Sylgard 184) mit 1 Gewichtsteil der kommerziellen Elastomer Härters (zB Sylgard 194). Typischerweise wurden 10 g Elastomer Base zu 1 g des Elastomer Härter mischen. </li><li> Rühren Sie die Basis und das Härtungsmittel mit einer Mikropipette für 5 min zu kombinieren. </li><li> Stellen Sie eine Vakuumglocke nach oben und legen Sie das wiegen Boot mit PDMS im Vakuum 30 min eingeschlossene Luftblasen zu entfernen. </li><li> Schalten Sie das Vakuum aus, und entfernen Sie das Boot wiegen. Gießen Sie die PDMS auf der Oberseite des Acryl-Ausschnitt in eine kleine Petrischale. Stellen Sie sicher, dass die PDMS vollständig den Einsatz abdeckt. </li><li> Lassen Sie die PDMS über Nacht aushärten (mindestens 18 h) bei Raumtemperatur. </li></ol></li><li> Entfernen des Einsatzes aus PDMS <ol><li> Nach der PDMS-Härtung, entfernen Sie den Einsatz von sorgfältig die PDMS um das Acryl-Stück mit einem Skalpell zu schneiden. </li></ol&gt; </li></ol> 2. Ausplattieren der Zellen in einem Mikrokanal Chamber <ol><li> Sterilisieren der Kammer zum Plattieren von Zellen. HINWEIS: Während kann PDMS unter Verwendung von Ethylenoxid oder andere Techniken sterilisiert werden, um eine schnelle UV-Behandlung ist schnell, billig und ausreichend für die Zellkulturstudien. Die kurze UV-Behandlungsdauer beeinträchtigte nicht die Struktur oder die mechanische Integrität des PDMS Stück. <ol><li> In einer Standard-Zellkulturschrank vollständig bedecken die Kammer mit 70% Ethanol. </li><li> Legen Sie die Petrischale in Laminar-Flow-Haube mit den Deckel ab. </li><li> Schließen Sie die Haube und schalten Sie das UV-Licht. Expose mit UV-Licht für 1-2 h. </li><li> Öffnen Sie die Laminarströmungsabzug und warten Sie 15 min Volumenstrom wiederherzustellen. </li><li> Entfernen Sie die 70% Ethanol. </li><li> Waschen Sie die Kammern zweimal mit steriler phosphatgepufferter Salzlösung (PBS). Verwenden Sie 1 ml PBS für jede Wäsche. Entfernen PBS und erlauben Kammern über Nacht mit den Deckel ab, um zu trocknen. HINWEIS: Alternativ kann statteine Laminarströmungsabzug der Verwendung eines UV-Kammer-Box für die Sterilisation verwendet werden, wenn ein solcher vorhanden ist. Machen Sie eine UV-Box durch eine UV-Lichtquelle in der Rückseite eines Karton ausgekleidet mit Aluminiumfolie platzieren. Die Aluminiumfolie reflektiert das Licht für eine gleichmäßige Ausleuchtung der Probe zu ermöglichen. </li></ol></li><li> Plating Cells in Kammer <ol><li> Zählen von Zellen unter Verwendung von Trypanblau und einer Zählkammer. <ol><li> Füge 100 &amp; mgr; l der Zellsuspension zu 400 ul von 0,4% Trypanblau und vorsichtig mischen. Anwenden 100 ul dieser Lösung in die Zählkammer durch vorsichtiges beide Kammern unter dem Deckglas gefüllt wird. </li><li> Verwenden Sie ein Mikroskop mit einem 10X-Objektiv auf das Gitter auf dem Hämocytometer zu konzentrieren. Verwenden Sie einen Handtallykostenzähler die Live-ungefärbten Zellen innerhalb eines Satzes von 16 Plätzen auf dem Hämocytometer zu zählen. </li><li> Zählen von Zellen in allen vier Sätzen von 16 Plätzen. Nehmen Sie die durchschnittliche Zellzahl von den vier Sätzen von 16 Plätzen und multiplizieren mit 5x10 4. Diese letzte Zahl ist die number von Zellen / ml in der Zellsuspension. </li></ol></li><li> In 2500 Zellen in eine Vertiefung in jeder Kammer. Dies führt zu einer nahezu konfluenten Zelldichte von ~ 30.000 / cm 2. </li><li> Erlauben Zellen für 60 min in der Kammer zu sitzen, bevor das Hinzufügen Medium (Dulbecco-modifiziertes Eagle-Medium, das 10% fötales Rinderserum, 1% Penicillin-Streptomycin). </li></ol></li></ol> 3. Dextran Soaked Agaroseblöcken <ol><li> Erstellen eines Agaroseblock <ol><li> Pour 3% Agarose in das 3D-Druckform (2 mm x 2 mm x 2 mm). </li><li> Erlauben die Agarose in einer Vakuumkammer zum Verfestigen für 30 min alle Blasen zu entfernen. </li><li> Entfernen Sie die Agarose-Block aus der Form. HINWEIS: Alternativ pour 3% Agarose in kleine Petrischale in einer Dicke von 2 mm. Schneiden Sie ein 2 mm x 2 mm x 2 mm Block mit einem Skalpell oder einem anderen Schneidwerkzeug. Das ist nicht so präzise wie die Formsystem, aber es kann ein wenig leichter zu tun. </li></ol></li><li> komplett submerge der Agarose-Block in einer Lösung der gewünschten Konzentration des chemotaktischen Faktors. Um die Konzentrationsgradienten Bildung beurteilen, spülen Sie die Kammer zunächst mit fluoreszierenden Dextran. Die Konzentration und Molekulargewicht von Dextran sollte einer löslichen Faktor oder Medikament von Interesse entsprechen. </li><li> Genießen Sie die Agarose-Block über Nacht. </li></ol> 4. Zeitraffer des Dextran Diffusion der löslichen Faktor Konzentrationsgradienten Beurteilen <ol><li> Legen Sie das Dextran getränkten Agaroseblock in einem kleinen Platz und der Mikrokanalkammer. </li><li> Setzen Sie den Mikrokanalkammer in einer Zelle-Bildgebungssystem oder verwenden Sie ein anderes Fluoreszenzmikroskop mit einem Zeitraffer-Fähigkeit. Beginnen Sie mit der Zeitraffer gemäß den Anweisungen des Herstellers. HINWEIS: Die angezeigten Ergebnisse sind mit GFP-Filter genommen, 50% Licht, 10.04 pH-Wert und 4-fache Vergrößerung. </li></ol> 5. Zeitraffer des Zellwachstums <ol><li> Platten Zellen in der Mikrokanalkammer an einem Ende derKammer. Hier verwenden 3T3 Fibroblasten. In 2500 Zellen in eine Vertiefung in der Mikrokanalkammer. Zählen von Zellen, wie in 2.2.1 beschrieben. <ol><li> Erlauben Zellen für 60 min in der Kammer zu sitzen, bevor das Hinzufügen Medium (Dulbecco-modifiziertes Eagle-Medium, das 10% fötales Rinderserum, 1% Penicillin-Streptomycin). Halten der Mikrokanalkammer , die mit plattierten Zellen bei 37 ° C in 5% CO 2. Zellmigration durch den Kanal kann mit einem Mikroskop betrachtet werden. </li><li> Fügen Sie einen Marker oder verwenden Sie eine mikroskopische Defekt in der Kammer als Marker, um als Ausgangspunkt dienen der Abstand zwischen der Zelle Front bewegt sich zu quantifizieren. </li></ol></li><li> Stellen Sie einen Gradienten durch ein Agarosegel Platzierung (8 mm 3 Block) , die das konzentrierte Wachstumsfaktor, chemo-Lockstoff, Medikament oder einem anderen Faktor getestet an einem Ende des Mikrokanals (hier 40% FBS als Beispiel wird verwendet) Kammer. </li><li> Nehmen Sie Zeitrafferbilder der sich bewegenden Zelle Front. Hier zeigen die Ergebnisse, Bilder der Zelle front waren, dass alle 12 h unter Verwendung eines Abbildungssystems genommen. </li><li> Verwenden Sie Bilder der Zelle Front Zellwachstumsrate zu quantifizieren. Berechnen Sie die Wachstumsrate, indem zuerst die MATLAB polyfit Funktion (roipoly) eine polygonale Maske von der Zelle Front, die Kanalwände und der Referenzmarke definiert zu erstellen. Die Abmessungen dieser Maske ergeben die Migrationsdistanz der vorderen, von dem mittleren Zellenfrontgeschwindigkeit berechnet wird. Andere Studien haben eine ähnliche Methode 8 verwendet. HINWEIS: Vergleichen der Rand des Zellwachstumsfront auf jedem Rahmen zu der Konzentration des löslichen Faktors in derselben Entfernung. Der lösliche Faktor Konzentrationsgradienten ist ein 1D-Diffusionsmodell Näherung berechnet. </li><li> Nehmen Fluoreszenzbilder der Zellen Phalloidin und DAPI-Färbung verwendet. <ol><li> Fix-Zellen, bevor sie mit Phalloidin-Färbung. <ol><li> Warm 4% Paraformaldehyd bei 37 ° C. </li><li> Fügen Sie genug 4% Paraformaldehyd Zellen zu decken. Halten der Zellen inParaformaldehyd für 10 min. </li><li> Spülen zweimal mit PBS für 15 Minuten jedes Mal. Verwenden Sie genug PBS um die Zellen zu decken. </li></ol></li><li> Entfernen PBS aus Zellen und fügen Sie genug permeabilisierend Lösung (0,1% Triton X-100 in PBS) Zellen zu decken. Lassen Lösung für 10 min. </li><li> Zweimal waschen mit PBS für jeweils 5 min. Verwenden Sie genug PBS um die Zellen zu decken. </li><li> Entfernen PBS aus Zellen und fügen Lösung (1% Rinderserumalbumin in PBS) für 20 min blockiert. </li><li> Entfernen Blockierungslösung und waschen 2-mal mit PBS für jeweils 5 min. Verwenden Sie genug PBS um die Zellen zu decken. </li><li> Von diesem Punkt, schützen die Zellen vor Licht mit Aluminiumfolie, wenn sie nicht verwendet werden. Entfernen PBS aus Zellen und fügen Phalloidin 488 1:50 verdünnt in PBS für 1 h. </li><li> Waschen Sie 2-mal in PBS für 5 Minuten für jede Wäsche. Verwenden Sie genug PBS um die Zellen zu decken. Dann entfernen PBS aus Zellen. </li><li> Hinzufügen DAPI (4 &#39;, 6-Diamidino-2-phenylindol), verdünnt 1: 1000 in PBS zu den Zellen für 15 min. </li><li> Entfernen Sie DAPI undwaschen Sie die Zellen zweimal mit PBS für 5 Minuten für jede Wäsche. </li><li> Entfernen letzten Waschen und fügen Sie genug PBS Zellen zu decken. Zellen können nun mit einem Fluoreszenzmikroskop abgebildet werden. </li></ol></li></ol>

<ol>
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(69), (2012).</li></ol>

Die Autoren haben nichts zu offenbaren.

Unsere Mikrokanalkammer kann für eine Vielzahl von Zwecken verwendet werden, einschließlich der Bestimmung der Zellmigrationsrate in Reaktion auf Wachstumsfaktoren und Lockstoffe und Messen der Diffusionsrate eines Arzneimittels aus einer Polymermatrix. Es ist möglich, unsere Mikrokanalkammer zu verwenden, Zellen wachsen zu lassen und einen chemoattractant an einem Ende der Kammer platzieren. Die Zellen wachsen in Reaktion auf die chemische Lockstoffe, und die Zellmigration können, indem sie Zeitrafferbilder quantif...

In order for vital processes such as wound healing, immune responses, and embryonic development to occur, cell migration must take place. Cell migration involves the interaction between cells and neighboring cells, the extracellular matrix, and soluble chemical cues (attractants or repellants). As an example, in the process of wound healing, fibroblasts play an integral role in fibrogenesis and wound contraction, where the cells are recruited to the site of injury to synthesize collagen in order to form the extracellular matrix3. Numerous mechanisms behind the migration of fibroblasts to a wound site have been studied, and they include different mechanical, physical, electrical, and chemotactic factors4. Fibroblasts respond especially well to different concentration gradients of growth factors. These different growth factors work together to optimize tissue regeneration5. While observing the chemotactic response of fibroblasts to growth factor concentrations, one can study the pattern of directional migration of fibroblasts and how they orient themselves around physical obstacles in order to reach their destination. Therefore, the goals of this study were to first develop a system in which fibroblast growth could be tracked under guidance by physical barriers and to secondly model the growth of fibroblasts as they navigate through the system.
Currently, the Boyden chamber assay is the most widely used system to measure the migration of cells6. The Boyden chamber consists of a two-chamber multi-well plate where each well may contain medium with or without chemoattractants7. A filter membrane provides a porous interface between the two chambers in each well; this creates a barrier so that cells cannot pass through unless it is by active migration. Typically, for the Boyden chamber, a chemoattractant is added to the lower chamber, and the system is allowed to equilibrate to form a gradient between the upper and lower wells4. One problem with the Boyden chamber assay is that steep gradients end up forming along a single axis perpendicular with the surface of the membrane. This causes the difference in the chemoattractant concentration between the upper and lower wells to be a lower than what was originally expected. Due to this constraint, the Boyden chamber assay makes it hard to correlate specific cell responses with particular gradient characteristics, such as the slope and the concentration difference. Without these measurements, it is hard to study multi-gradient signal integration.
To address some of the constraints of the traditional Boyden chamber assay, microfluidic assays have been developed to form customizable concentration gradients1. Standard methods for creating microfluidic systems require clean rooms for lithographic techniques. These techniques can be difficult to learn especially in a standard classroom setting. Thus, we have designed a chamber system for measuring cell migration that can be made without using a clean room. Using our system, the wells of the assay can be adjusted to a preferred size, and a linear concentration gradient of customized slope can be produced. This allows for accurate measurement of chemotaxis from random movement. The design is an inexpensive and easy-to-use system to model cell growth in response to different chemical stimuli.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Sylgard 184 Silicone Elastomer Kit</td>
			<td>Sigma-Aldrich</td>
			<td>761036</td>
			<td>poly(dimethylsiloxane) 2-part kit including silicone elastomer base and silicone elastomer curing agent</td>
		</tr>
		<tr>
			<td>Acrylic Sheets</td>
			<td>US Plastic</td>
			<td>44200</td>
			<td></td>
		</tr>
		<tr>
			<td>Disposable Petri Dishes&#160;</td>
			<td>Falcon&#160;</td>
			<td>25373-041</td>
			<td></td>
		</tr>
		<tr>
			<td>Fluorescein isothiocyanate&#8211;dextran</td>
			<td>Sigma-Aldrich</td>
			<td>FD20s-100MG</td>
			<td></td>
		</tr>
		<tr>
			<td>Agarose, Type I, Low EEO</td>
			<td>Sigma-Aldrich</td>
			<td>A6013-100G</td>
			<td></td>
		</tr>
		<tr>
			<td>Dulbecco&#39;s Modified Eagle&#39;s Medium</td>
			<td>Fisher Scientific</td>
			<td>11965092</td>
			<td>Cell media components</td>
		</tr>
		<tr>
			<td>Fetal Bovine Serium</td>
			<td>Fisher Scientific</td>
			<td>16000036</td>
			<td>Cell media components</td>
		</tr>
		<tr>
			<td>Penicillin-streptomycin</td>
			<td>Fisher Scientific</td>
			<td>15140148</td>
			<td>Cell media components</td>
		</tr>
		<tr>
			<td>Phosphate Buffered Saline (PBS)</td>
			<td>Fisher Scientific</td>
			<td>BP24384</td>
			<td></td>
		</tr>
		<tr>
			<td>EVOS XL Cell Imaging System</td>
			<td>Thermo Fisher Scientific</td>
			<td>AME3300</td>
			<td>Instrument used for taking time-lapse images</td>
		</tr>
		<tr>
			<td>Versa LASER</td>
			<td>Universal Laser Systems, Inc.&#160;</td>
			<td>Model number VLS2.30</td>
			<td>Laser cutter used for cutting plastic</td>
		</tr>
	</tbody>
</table>

a customizable chamber for measuring cell migration

Die Zellmigration ist ein wichtiger Teil der Immunantwort, Wachstum und Wundheilung. Die Zellmigration ist ein komplexer Prozess, der Wechselwirkungen zwischen Zellen, die extrazelluläre Matrix, und löslichen und nicht-löslichen chemischen Faktoren (zB chemische Lockstoffe) beinhaltet. Standardmethoden für die Migration von Zellen zu messen, wie der Boyden-Kammer-Assay, der Arbeit von Zellen auf beiden Seiten eines Teilers zu zählen. Diese Techniken sind einfach zu bedienen; Sie bieten jedoch wenig geometrische Modifikation für verschiedene Anwendungen. Im Gegensatz dazu können Mikrofluidik - Vorrichtungen verwendet werden , die Zellmigration mit anpassbaren Konzentrationsgradienten von löslichen Faktoren 1, 2 zu beobachten. Allerdings Methoden für Mikrofluidik basierte Assays machen kann schwierig sein, zu lernen. Hier beschreiben wir eine einfache Methode zur Erzeugung von Zellkulturkammern die Zellmigration in Reaktion auf die chemischen Konzentrationsgradienten zu messen. Unsere Zelle migration Kammerverfahren verschiedene lineare Konzentrationsgradienten, um zu schaffen Zellmigration für eine Vielzahl von Anwendungen zu untersuchen. Dieses Verfahren ist relativ einfach zu bedienen und wird in der Regel von Studenten durchgeführt. Die Mikrokanalkammer wurde durch Einbringen eines Acryleinlage in der Form des endgültigen Mikrokanalkammer und in eine Petrischale geschaffen. Danach wird Poly (dimethylsiloxan) (PDMS) wurde auf die Oberseite des Einsatzes gegossen. Das PDMS wurde härten gelassen und dann wurde die Einlage entfernt. Dies ermöglichte die Schaffung von Vertiefungen in jeder gewünschten Form oder Größe. Zellen anschließend in die Mikrokanalkammer hinzugefügt werden können, und löslichen Mittel können durch Einweichen eines Agarose-Block in dem gewünschten Mittels zu einer der Vertiefungen zugegeben werden. Die Agarose-Block wird zu einer der Vertiefungen gegeben, und Zeitraffer-Bilder können in der Reihenfolge der Mikrokanalkammer entnommen werden, die Zellmigration zu quantifizieren. Änderungen dieses Verfahrens kann für eine gegebene Anwendung gemacht werden, diese Methode hig machenhly anpassbar.

Figur 2 zeigt die Bewegung der Zellenfront über den Kanal als Reaktion auf einen Gradienten von fötalem Rinderserum am entgegengesetzten Ende des Kanals angeordnet , von dem die Zellen ausplattiert. Die Zellfront wird bei 48 h (2A) gezeigt, 72 h (2B), 96 h (2C) und 120 h (Figur 2D) Post plating. Die Bewegung der Zellenfront wurde mit diesen Zeitraffer-Bildern verfolgt, und die Laufstrecke und die Wachs...

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A Customizable Chamber for Measuring Cell Migration

Dieses Protokoll Informationen eine anpassbare Methode Zellmigration in Reaktion auf die chemischen Lockstoffe zu messen, die auch die Diffusionsgeschwindigkeit eines Arzneimittels verwendet werden kann, aus einer Polymermatrix zu bestimmen.

Eine Anpassbare Kammer zur Messung der Zellmigration

Cell migration is a vital part of immune responses, growth, and wound healing. Cell migration is a complex process that involves interactions between ...

a-customizable-chamber-for-measuring-cell-migration

Research

JoVE Journal

Biology

10.5K Aufrufe.  Clemson University.  Dieses Protokoll Informationen eine anpassbare Methode Zellmigration in Reaktion auf die chemischen Lockstoffe zu messen, die auch die Diffusionsgeschwindigkeit eines Arzneimittels verwendet werden kann, aus einer Polymermatrix zu bestimmen. 

Serie: A Customizable Chamber for Measuring Cell Migration

Measuring Exocytosis in Neurons Using FM Labeling

The ability to measure the kinetics of vesicle release can help provide insight into some of the basics of neurotransmission.  Here we used real-time imaging of vesicles labeled with FM dye to monitor the rate of presynaptic vesicle release.  FM4-64 is a red fluorescent amphiphilic styryl dye that embeds into the membranes of synaptic vesicles as endocytosis is stimulated.  Lipophilic interactions cause the dye to greatly increase in fluorescence, thus emitting a bright signal when associated with vesicles and a nominal one when in the extracellular fluid. After a wash step is used to help remove external dye within the plasma membrane, the remaining FM is concentrated within the vesicles and is then expelled when exocytosis is induced by another round of electrical stimulation. The rate of vesicles release is measured from the resulting decrease in fluorescence.  Since FM dye can be applied external and transiently, it is a useful tool for determining rates of exocytosis in neuronal cultures, especially when comparing the rates between transfected synapses and neighboring control boutons.



The ability to measure the kinetics of vesicle release can help provide insight into some of the basics of neurotransmission. Here we used real-time imaging of vesicles labeled with the red fluorescent dye FM 4-64 to measure the rate of presynaptic vesicle release in hippocampal neuronal cultures.

Mess-Exocytose in Neuronen mit FM Labeling

The ability to measure the kinetics of vesicle release can help provide insight into some of the basics of neurotransmission.  Here we used real-time ...

Forschung

Biologie

Brain Slice Stimulation Using a Microfluidic Network and Standard Perfusion Chamber

We have demonstrated the fabrication of a two-level microfluidic device that can be easily integrated with existing electrophysiology setups. The two-level microfluidic device is fabricated using a two-step standard negative resist lithography process 1. The first level contains microchannels with inlet and outlet ports at each end. The second level contains microscale circular holes located midway of the channel length and centered along with channel width. Passive pumping method is used to pump fluids from the inlet port to the outlet port 2. The microfluidic device is integrated with off-the-shelf perfusion chambers and allows seamless integration with the electrophysiology setup. The fluids introduced at the inlet ports flow through the microchannels towards the outlet ports and also escape through the circular openings located on top of the microchannels into the bath of the perfusion. Thus the bottom surface of the brain slice placed in the perfusion chamber bath and above the microfluidic device can be exposed with different neurotransmitters. The microscale thickness of the microfluidic device and the transparent nature of the materials [glass coverslip and PDMS (polydimethylsiloxane)] used to make the microfluidic device allow microscopy of the brain slice. The microfluidic device allows modulation (both spatial and temporal) of the chemical stimuli introduced to the brain slice microenvironments.

We demonstrate fabrication of a simple microfluidic device that can be integrated with standard electrophysiology setups to expose microscale surfaces of a brain slice in a well controlled manner to different neurotransmitters.

Hirnschnitt Stimulation mit einem mikrofluidischen Netzwerk-und Standard-Perfusionskammer

We have demonstrated the fabrication of a two-level microfluidic device that can be easily integrated with existing electrophysiology setups. The ...

Live Imaging of Glial Cell Migration in the Drosophila Eye Imaginal Disc

Glial cells of both vertebrate and invertebrate organisms must migrate to final target regions in order to ensheath and support associated neurons. While recent progress has been made to describe the live migration of glial cells in the developing pupal wing (1), studies of Drosophila glial cell migration have typically involved the examination of fixed tissue. Live microscopic analysis of motile cells offers the ability to examine cellular behavior throughout the migratory process, including determining the rate of and changes in direction of growth. Paired with use of genetic tools, live imaging can be used to determine more precise roles for specific genes in the process of development. Previous work by Silies et al. (2) has described the migration of glia originating from the optic stalk, a structure that connects the developing eye and brain, into the eye imaginal disc in fixed tissue. Here we outline a protocol for examining the live migration of glial cells into the Drosophila eye imaginal disc. We take advantage of a Drosophila line that expresses GFP in developing glia to follow glial cell progression in wild type and in mutant animals.

Here we describe a protocol to examine the migration of glial cells into the developing Drosophila eye using live microscopic analysis paired with GFP tagged glial cells.

Live-Imaging von Gliazellen Migration in der Drosophila Eye Imaginalscheibe

Glial cells of both vertebrate and invertebrate organisms must migrate to final target regions in order to ensheath and support associated neurons.  While ...

Measuring the Bending Stiffness of Bacterial Cells Using an Optical Trap

We developed a protocol to measure the bending rigidity of filamentous rod-shaped bacteria. Forces are applied with an optical trap, a microscopic three-dimensional spring made of light that is formed when a high-intensity laser beam is focused to a very small spot by a microscope's objective lens. To bend a cell, we first bind live bacteria to a chemically-treated coverslip. As these cells grow, the middle of the cells remains bound to the coverslip but the growing ends are free of this restraint. By inducing filamentous growth with the drug cephalexin, we are able to identify cells in which one end of the cell was stuck to the surface while the other end remained unattached and susceptible to bending forces. A bending force is then applied with an optical trap by binding a polylysine-coated bead to the tip of a growing cell. Both the force and the displacement of the bead are recorded and the bending stiffness of the cell is the slope of this relationship.

We present a protocol for bending filamentous bacterial cells attached to a cover-slip surface with an optical trap to measure the cellular bending stiffness.

Die Messung der Biegesteifigkeit von Bakterienzellen mit einer optischen Falle

We developed a protocol to measure the bending rigidity of filamentous rod-shaped bacteria. Forces are applied with an optical trap, a microscopic ...

An Assay for Measuring the Activity of Escherichia coli Inducible Lysine Decarboxyase

Escherichia coli is an enteric bacterium that is capable of growing over a wide range of pH values (pH 5 - 9)1 and, incredibly, is able to survive extreme acid stresses including passage through the mammalian stomach where the pH can fall to as low as pH 1 - 22. To enable such a broad range of acidic pH survival, E. coli possesses four different inducible amino acid decarboxylases that decarboxylate their substrate amino acids in a proton-dependent manner thus raising the internal pH. The decarboxylases include the glutamic acid decarboxylases GadA and GadB3, the arginine decarboxylase AdiA4, the lysine decarboxylase LdcI5, 6 and the ornithine decarboxylase SpeF7. All of these enzymes utilize pyridoxal-5'-phospate as a co-factor8 and function together with inner-membrane substrate-product antiporters that remove decarboxylation products to the external medium in exchange for fresh substrate2. In the case of LdcI, the lysine-cadaverine antiporter is called CadB. Recently, we determined the X-ray crystal structure of LdcI to 2.0 &#197;, and we discovered a novel small-molecule bound to LdcI the stringent response regulator guanosine 5'-diphosphate,3'-diphosphate (ppGpp) 14. The stringent response occurs when exponentially growing cells experience nutrient deprivation or one of a number of other stresses9. As a result, cells produce ppGpp which leads to a signaling cascade culminating in the shift from exponential growth to stationary phase growth10. We have demonstrated that ppGpp is a specific inhibitor of LdcI 14. Here we describe the lysine decarboxylase assay, modified from the assay developed by Phan et al.11, that we have used to determine the activity of LdcI and the effect of pppGpp/ppGpp on that activity. The LdcI decarboxylation reaction removes the &alpha;-carboxy group of L-lysine and produces carbon dioxide and the polyamine cadaverine (1,5-diaminopentane)5. L-lysine and cadaverine can be reacted with 2,4,6-trinitrobenzensulfonic acid (TNBS) at high pH to generate N,N'-bistrinitrophenylcadaverine (TNP-cadaverine) and N,N&#8242;-bistrinitrophenyllysine (TNP-lysine), respectively11. The TNP-cadaverine can be separated from the TNP-lysine as the former is soluble in organic solvents such as toluene while the latter is not (See Figure 1). The linear range of the assay was determined empirically using purified cadaverine.

An Assay for Measuring the Activity of Escherichia coli Inducible Lysine Decarboxyase

The activity of the inducible lysine decarboxylase is monitored by reacting the substrate L-lysine and the product cadaverine with 2,4,6-trinitrobenzensulfonic acid to form adducts that have differential solubility in toluene.

Ein Assay zur Messung der Aktivität von Escherichia coli Inducible Lysin Decarboxyase

Escherichia coli is an enteric bacterium that is capable of growing over a wide range of pH values (pH 5 - 9)1 and, incredibly, is able to survive extreme ...

Intravital Microscopy of the Microcirculation in the Mouse Cremaster Muscle for the Analysis of Peripheral Stem Cell Migration

In the era of intravascular cell application protocols in the context of regenerative cell therapy, the underlying mechanisms of stem cell migration to nonmarrow tissue have not been completely clarified. We describe here the technique of intravital microscopy applied to the mouse cremaster microcirculation for analysis of peripheral bone marrow stem cell migration in vivo. Intravital microscopy of the M. cremaster has been previously introduced in the field of inflammatory research for direct observation of leucocyte interaction with the vascular endothelium. Since sufficient peripheral stem and progenitor cell migration includes similar initial steps of rolling along and firm adhesion at the endothelial lining it is conceivable to apply the M. cremaster model for the observation and quantification of the interaction of intravasculary administered stem cells with the endothelium. As various chemical components can be selectively applied to the target tissue by simple superfusion techniques, it is possible to establish essential microenvironmental preconditions, for initial stem cell recruitment to take place in a living organism outside the bone marrow.

Intravital microscopy of the mouse M. cremaster microcirculation offers a unique and well-standardized in vivo model for the analysis of peripheral bone marrow stem cell migration.

Intravitalmikroskopie der Mikrozirkulation in der Maus Cremaster-Muskel für die Analyse der peripheren Stammzell Migration

In the era of intravascular cell application protocols in the context of regenerative cell therapy, the underlying mechanisms of stem cell migration to ...

Single-cell Microinjection for Cell Communication Analysis

Gap junctions are intercellular channels that allow the communication of neighboring cells. This communication depends on the contribution of a hemichannel by each neighboring cell to form the gap junction. In mammalian cells, the hemichannel is formed by six connexins, monomers with four transmembrane domains and a C and N terminal within the cytoplasm. Gap junctions permit the exchange of ions, second messengers, and small metabolites. In addition, they have important roles in many forms of cellular communication within physiological processes such as synaptic transmission, heart contraction, cell growth and differentiation. We detail how to perform a single-cell microinjection of Lucifer Yellow to visualize cellular communication via gap-junctions in living cells. It is expected that in functional gap junctions, the dye will diffuse from the loaded cell to the connected cells. It is a very useful technique to study gap junctions since you can evaluate the diffusion of the fluorescence in real time. We discuss how to prepare the cells and the micropipette, how to use a micromanipulator and inject a low molecular weight fluorescent dye in an epithelial cell line.

We describe here how to perform a single-cell microinjection of Lucifer Yellow to visualize cellular communication via gap-junctions in living cells, and provide some useful tips. We expect that this paper will help everyone to evaluate the degree of cellular coupling due to functional gap junctions. Everything described here could be, in principle, adapted to other fluorescent dyes with molecular weight below 1,000 Daltons.

Einzellige Mikroinjektions für Zellkommunikationsanalyse

Gap junctions are intercellular channels that allow the communication of neighboring cells. This communication depends on the contribution of a ...

In vitro Cell Migration and Invasion Assays

Migration is a key property of live cells and critical for normal development, immune response, and disease processes such as cancer metastasis and inflammation. Methods to examine cell migration are very useful and important for a wide range of biomedical research such as cancer biology, immunology, vascular biology, cell biology and developmental biology. Here we use tumor cell migration and invasion as an example and describe two related assays to illustrate the commonly used, easily accessible methods to measure these processes. The first method is the cell culture wound closure assay in which a scratch is generated on a confluent cell monolayer. The speed of wound closure and cell migration can be quantified by taking snapshot pictures with a regular inverted microscope at several time intervals. More detailed cell migratory behavior can be documented using the time-lapse microscopy system. The second method described in this paper is the transwell cell migration and invasion assay that measures the capacity of cell motility and invasiveness toward a chemo-attractant gradient. It is our goal to describe these methods in a highly accessible manner so that the procedures can be successfully performed in research laboratories even just with basic cell biology setup.

In vitro Cell Migration and Invasion Assays

Commonly used, highly accessible methods for examining cell migration and invasion in vitro are described. The first method is the cell wound closure assay that measures cell motility. The second method is the transwell migration and invasion assay that assesses the chemotactic and invasive capacity of cells.

In-vitro-Zellmigration und Invasion Assays

Migration is a key property of live cells and critical for normal development, immune response, and disease processes such as cancer metastasis and ...

Imaging Intermediate Filaments and Microtubules with 2-dimensional Direct Stochastic Optical Reconstruction Microscopy

The cytoskeleton, composed of actin microfilaments, microtubules, and intermediate filaments (IF), plays a key role in the control of cell shape, polarity, and motility. The organization of the actin and microtubule networks has been extensively studied but that of IFs is not yet fully characterized. IFs have an average diameter of 10 nm and form a network extending throughout the cell cytoplasm. They are physically associated with actin and microtubules through molecular motors and cytoskeletal linkers. This tight association is at the heart of the regulatory mechanisms that ensure the coordinated regulation of the three cytoskeletal networks required for most cell functions. It is therefore crucial to visualize IFs alone and also together with each of the other cytoskeletal networks. However, IF networks are extremely dense in most cell types, especially in glial cells, which makes its resolution very difficult to achieve with standard fluorescence microscopy (lateral resolution of ~250 nm). Direct STochastic Optical Reconstruction Microscopy (dSTORM) is a technique allowing a gain in lateral resolution of one order of magnitude. Here, we show that lateral dSTORM resolution is sufficient to resolve the dense organization of the IF networks and, in particular, of IF bundles surrounding microtubules. Such tight association is likely to participate in the coordinated regulation of these two networks and may, explain how vimentin IFs template and stabilize microtubule organization as well as could influence microtubule dependent vesicular trafficking. More generally, we show how the observation of two cytoskeletal components with dual-color dSTORM technique brings new insight into their mutual interaction.

The overall goal of this methodology is to give the optimal experimental conditions from sample preparation to image acquisition and reconstruction in order to perform 2D dual color dSTORM images of microtubules and intermediate filaments in fixed cells

Imaging-Intermediate Filamenten und Mikrotubuli mit 2-dimensionale direkte stochastische optische Rekonstruktion Mikroskopie

The cytoskeleton, composed of actin microfilaments, microtubules, and intermediate filaments (IF), plays a key role in the control of cell shape, ...

Optimized Scratch Assay for In Vitro Testing of Cell Migration with an Automated Optical Camera

Cell migration is an important process that influences many aspects of health, such as wound healing and cancer, and it is, therefore, crucial for developing methods to study the migration. The scratch assay has long been the most common in vitro method to test compounds with anti- and pro-migration properties because of its low cost and simple procedure. However, an often-reported problem of the assay is the accumulation of cells across the edge of the scratch. Furthermore, to obtain data from the assay, images of different exposures must be taken over a period of time at the exact same spot to compare the movements of the migration. Different analysis programs can be used to describe the scratch closure, but they are labor intensive, inaccurate, and forces cycles of temperature changes. In this study, we demonstrate an optimized method for testing the migration effect, e.g. with the naturally occurring proteins Human- and Bovine-Lactoferrin and their N-terminal peptide Lactoferricin on the epithelial cell line HaCaT. A crucial optimization is to wash and scratch in PBS, which eliminates the aforementioned accumulation of cells along the edge. This could be explained by the removal of cations, which have been shown to have an effect on keratinocyte cell-cell connection. To ensure true detection of migration, pre-treating with mitomycin C, a DNA synthesis inhibitor, was added to the protocol. Finally, we demonstrate the automated optical camera, which eliminates excessive temperature cycles, manual labor with scratch closure analysis, while improving on reproducibility and ensuring analysis of identical sections of the scratch over time.

Optimized Scratch Assay for In Vitro Testing of Cell Migration with an Automated Optical Camera

Here we describe a procedure to test the cell migration in vitro with an automated optical camera microscope. The scratch assay has been widely used where the closure of the scratch is followed for a set period. The optical microscope enables dependable and cheap detection of cell migration.