Os autores agradecem grandemente a plataforma PICT IBISA no Institut Curie (CNRS UMR144). Este trabalho foi financiado por concessões: o Conselho Europeu de Investigação para AM.LD (Strapacemi 243103), a Associação Nationale pour la Recherche (ANR-09-piri-0027-PCVI), a fundação InnaBiosanté (Micemico) para MP e PM. LD ea ERC Strapacemi jovem concessão investigador AM.LD.

Importante: Este protocolo assume que o molde contendo a forma para os microcanais desejados já foi feita. Outras informações sobre a preparação do molde já foi publicado em 10 de. Este protocolo também assume que DCs medula óssea cultura é conhecido. 1. Chip Fabrication <ol><li> Misture o óleo de PDMS e agente de cura em um 10:1 de peso em um copo de plástico. Misturar os dois compostos completamente. </li><li> Lançai a mistura ao longo dos microcanais rolamento do molde. A altura total deve estar compreendida entre 0,5-1 cm. </li><li> Remova as bolhas de ar em uma redoma de vácuo durante 1 hora. </li><li> PDMS endureça no molde, colocando este último num forno durante 2 horas a 65 ° C. </li><li> Uma vez que o PDMS é, à temperatura ambiente, cortado um pedaço grande em torno da estrutura, com uma lâmina de bisturi e retire-a a partir do molde (Figura 1A). </li><li> Faça furos onde as células serão injetadas (tipicamente 2 mm) e redimensionar o PDMScom uma lâmina cirúrgica para ajustar o tamanho de pratos com fundo de vidro em que a migração serão avaliados (Figura 1B). Antes de prosseguir, remover o pó residual do prato usando lente papel de limpeza. Isto favorece a ligação de PDMS de vidro descrito na etapa 1.10. </li><li> Limpe o chip redimensionada PDMS contendo os canais por degola e descamação fita adesiva nas laterais da estrutura. </li><li> Sonicar os pedaços PDMS 30 segundos em 70% de etanol para remover as poeiras e as pequenas partículas de PDMS. Seque-os rapidamente depois soprando ar limpo. </li><li> Ative os PDMS (estruturas para cima) e placas de cultura de ar (ou oxigênio) o tratamento de plasma durante 30 segundos a 300 mTorr. </li><li> Coloque ambas as superfícies ativadas em contato para ficar permanentemente os PDMS ao substrato. Se necessário, utilizar uma pinça metálica para pressionar ligeiramente por cima do PDMS de forçar o contacto entre o polímero e o vidro do prato (Figura 1C). </li><li> Incubar o chip no forno a 65 ° C for 1 hr para fortalecer a ligação. </li></ol> 2. Revestimento de microcanais <ol><li> Activar a toda a estrutura por plasma de ar a 300 mTorr durante 1 min. Isto vai promover a entrada de líquido para dentro dos canais no passo seguinte. </li><li> Encher rapidamente os orifícios de entrada do chip com fibronectina a 10 ug / ml em água. Outros substratos, tais como PEG podem ser utilizados para modificar a aderência celular para as paredes do canal. Preste atenção que o líquido se espalha por toda a estrutura. Isto pode ser facilmente verificado por olho sob luz normal ou usando um microscópio de campo claro regular. NOTA: Em estruturas muito pequenas, nas quais a difusão é mais difícil, a entrada de líquido nos canais podem ser forçados através da colocação da estrutura numa campânula de vácuo durante pelo menos 15 min. Para verificar a eficiência do revestimento de substratos fluorescentes pode ser utilizado (Figura 2). </li><li> Incubar 1 hora à temperatura ambiente para permitir a adsorção da fibronectina ou qualquer outro revestimento substtaxa para as paredes dos canais. </li><li> Lavar as estruturas 3x com PBS para remover o substrato nonbound. </li><li> Após a lavagem, passe para protocolo 3 ou armazenar o chip a 4 ° C para um uso posterior (24 máximo hr). </li></ol> 3. Célula de carga <ol><li> Remover o PBS a partir da placa e preencher o microsistema com meio celular. Deixe-incubar durante 1 hora para saturar os canais com o meio. NOTA: Para os experimentos que envolvem drogas como inibidores de molécula, é aconselhável pré-incubar os canais com um meio contendo a droga na concentração correta. Além disso, alguns medicamentos tendem a solubilizar na estrutura PDMS que reduz a concentração eficaz. Algumas soluções têm sido propostas para contrariar este problema 11-12. </li><li> Remover DCs flutuantes e recuperar as células semi-aderentes por lavagem com meio de cultura. Contagem de células utilizando um hemocitómetro. NOTA: Para imagens de núcleo, uma coloração de Hoechst 33342 pode ser conseguido por no antemãocubating 2 x 10 6 células durante 30 minutos com o corante a 200 ng / ml em meio completo. Lavar duas vezes por centrifugação para remover o excesso de corante, antes de continuar o protocolo. </li><li> Centrifugar as células a 300 xg durante 5 minutos (o tempo e a velocidade pode ser diferente, dependendo do tipo de célula) e descartar o meio. Dilui-se o sedimento para atingir uma concentração de 20 x 10 6 células / ml. </li><li> Remover o excesso de meio da placa e esvaziar os orifícios de entrada na estrutura de PDMS usando uma micropipeta. Encha as entradas com 5 mL de solução de células para atingir uma quantidade de 1 x 10 5 células em cada orifício de entrada. NOTA: Alta densidade celular é necessária para favorecer o contacto das células com os canais. Baixa densidade celular pode resultar em menor número de células no interior de canais e fracasso da experiência. </li><li> Incubar o microchip durante 30 min a 37 ° C na incubadora. Adicionar 2 ml de meio completo para o ensaio de prato. NOTA: A estrutura inteira PDMS deve be coberto a fim de evitar a secagem das células durante a experiência. Se 2 ml não é suficiente, adicione mais meio para cobrir completamente a estrutura de PDMS. </li></ol> 4. Imagem <ol><li> Limpar a superfície inferior externa dos pratos com tecido de limpeza de lentes antes da colocação das placas sob o microscópio. </li><li> Para analisar a migração em grande número de células, usar ampliação de 10X e de iluminação de campo numa ampla de CO 2 e de temperatura equipado de vídeo-microscópio (Figura 3). Para facilitar o rastreamento de pilha, Hoechst coloração e luz UV pode ser usado (veja o passo 3.2). A migração pode ser também analisados ​​usando microscopia confocal a fim de obter maior resolução de estruturas celulares durante a migração. </li><li> Para a microscopia de lapso de tempo em 10X, escolha uma frequência de tempo de acordo com a velocidade da célula esperada (tipicamente 2 min para as células dendríticas que migram com uma velocidade de 5 mm / min). Nota: O protocolo descrito aqui faz not incluem a análise dos parâmetros de migração celular. Alguns pontos são listados na discussão para aconselhar os leitores sobre como proceder para extrair informações a partir de filmes de lapso de tempo. </li></ol>

<ol>
	<li>Lauffenburger, D. A., Horwitz, A. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+migration:+a+physically+integrated+molecular+process.">Cell migration: a physically integrated molecular process.</a> Cell. 84 (3), 359-369 (1996).</li><li>L&#228;mmermann, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+leukocyte+migration+by+integrin-independent+flowing+and+squeezing.">Rapid leukocyte migration by integrin-independent flowing and squeezing.</a> Nature. 453 (7191), 51-55 (2008).</li><li>Schor, S. L., Allen, T. D., Harrison, C. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+migration+through+three-dimensional+gels+of+native+collagen+fibres:+collagenolytic+activity+is+not+required+for+the+migration+of+two+permanent+cell+lines.">Cell migration through three-dimensional gels of native collagen fibres: collagenolytic activity is not required for the migration of two permanent cell lines.</a> J. Cell. Sci. 41, 159-175 (1980).</li><li>Steinman, R. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Decisions+about+dendritic+cells:+past,+present,+and+future.">Decisions about dendritic cells: past, present, and future.</a> Annu. Rev. Immunol. 30, 1-22 (2012).</li><li>Faure-Andr&#233;, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regulation+of+dendritic+cell+migration+by+CD74,+the+MHC+class+II-associated+invariant+chain.">Regulation of dendritic cell migration by CD74, the MHC class II-associated invariant chain.</a> Science. 322 (5908), 1705-1710 (2008).</li><li>Renkawitz, J., 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=Adaptive+force+transmission+in+amoeboid+cell+migration.">Adaptive force transmission in amoeboid cell migration.</a> Nat. Cell Biol. 11 (12), 1438-1443 (2008).</li><li>Jacobelli, J., 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=Confinement-optimized+three-dimensional+T+cell+amoeboid+motility+is+modulated+via+myosin+IIA-regulated+adhesions.">Confinement-optimized three-dimensional T cell amoeboid motility is modulated via myosin IIA-regulated adhesions.</a> Nat. Immunol. 11 (10), 953-961 (2010).</li><li>Irimia, D., Charras, G., Agrawal, N., Mitchinson, T., Toner, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polar+stimulation+and+constrained+cell+migration+in+microfluidic+channels.">Polar stimulation and constrained cell migration in microfluidic channels.</a> Lab Chip. 7 (12), 1783-1790 (2007).</li><li>Moreau, 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=Dynamic+in+situ+cytometry+uncovers+T+cell+receptor+signaling+during+immunological+synapses+and+kinapses+in+vivo.">Dynamic in situ cytometry uncovers T cell receptor signaling during immunological synapses and kinapses in vivo.</a> Immunity. 37 (2), 351-363 (2012).</li><li>Heuz&#233;, M. L., Collin, O., Terriac, E., Lennon-Dum&#233;nil, A. M., Piel, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+migration+in+confinement:+a+micro-channel-based+assay.">Cell migration in confinement: a micro-channel-based assay.</a> Methods Mol. Biol. 769, 415-434 (2011).</li><li>Ren, K., Zhao, Y., Su, J., Ryan, D., Wu, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Convenient+method+for+modifying+poly(dimethylsiloxane)+to+be+airtight+and+resistive+against+absorption+of+small+molecules.">Convenient method for modifying poly(dimethylsiloxane) to be airtight and resistive against absorption of small molecules.</a> Anal. Chem. 82 (14), 5965-5971 (2010).</li><li>Ren, K., Dai, W., Zhou, J., Su, J., Wu, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Whole-Teflon+microfluidic+chips.">Whole-Teflon microfluidic chips.</a> PNAS. 108 (20), 8162-8166 (2011).</li><li>Maiuri, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+first+World+Cell+Race.">The first World Cell Race.</a> Curr Biol. 22 (17), 673-675 (2012).</li></ol>

Os autores não têm nada a revelar.

Descrevemos aqui um dispositivo composto por microcanais como um método para estudar as propriedades migratórias de grande número de células em experiências individuais. Este sistema experimental imita as restrições ambientais confinados encontradas em tecidos de células migratórias endógenos. No entanto, forçando a migração de uma única dimensão, que facilita o controle automático de células e a extracção da mensuráveis ​​(Figura 5). Também mostram que o nosso dispositivo é co...

A migração é uma função celular complexa que é importante para diversos processos fisiológicos em organismos multicelulares, incluindo o desenvolvimento, respostas imunitárias, e a regeneração de tecidos. Além disso, certas situações patológicas, tais como a invasão do tumor e metástases dependem de motilidade celular 1. Por estas razões, a migração celular tornou-se um importante campo de estudo no contexto de investigação fundamental e de translação. In vivo, a maioria dos tecidos são caracterizado por uma matriz extracelular rica e elevada densidade celular. A migração celular, por conseguinte, em condições fisiológicas, ocorre num ambiente confinado complexo. Classicamente, muito provavelmente devido a razões históricas e limites técnicos, a migração de células foi estudada em sistemas 2d plana que não se reproduzem muitas das propriedades ambientais encontradas em tecidos, tais como o confinamento. Além disso, os factores como a adesão de células, que são essenciais para a motilidade em 2D, foram recentemente mostrou não ser necessariamente necessária para a migração in vivo, ou dentro geles, o que sugere que os mecanismos que governam a locomoção das células em 2D e em outros ambientes são distintos 2. Vários sistemas têm sido desenvolvidos para imitar as propriedades do complexo de tecidos, o mais famoso géis de colagénio, sendo que visam recapitulando as propriedades da composição da matriz extracelular 3. Aqui propomos microcanais como método complementar simples que permite a migração de células de estudo em uma dimensão em um ambiente confinado. Neste sistema, as células migram ao longo de microcanais em que eles entram espontaneamente. Células migratórias então adquirir a forma dos canais, que adopta uma geometria tubular que provavelmente reforça a sua polaridade. O movimento linear das células dos canais permite o seguimento automático de células e a extracção de parâmetros quantitativos obtidos em experiências. Do ponto de vista técnico, este sistema é fácil e flexível. O coating das paredes do canal pode ser manipulado, o tamanho e a forma dos canais pode ser adaptado, e um grande número de células pode ser analisada em experiências individuais. Este sistema pode também ser ampliado para realizar a análise de tela intervalo médio de moléculas envolvidas na motilidade celular. O protocolo aqui descrito foi normalizado utilizando células dendríticas (DC) como um modelo celular. Estas células são a chave para o sistema imunitário que eles participam na iniciação e manutenção de respostas imunitárias específicas 4. In vitro, DCs foram mostrados para migrar espontaneamente em ambientes confinados, e são, portanto, um bom modelo para estudar a motilidade celular em microcanais 5,6 . Importante, este sistema pode ser ampliado para analisar a migração de qualquer outro tipo de células móveis, como os linfócitos T, neutrófilos, células de tumor ou 7-9.

<table border="0" cellpadding="0" cellspacing="0" width="947">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="20">
			<td height="20" style="height:20px;width:273px;">PolyDimethylSiloxane (PDMS)</td>
			<td style="width:131px;">GE Silicones</td>
			<td style="width:139px;">RTV615</td>
			<td style="width:405px;">Package of 90% silicone base and 10% curing agent</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Core sample cutter</td>
			<td>Ted Pella Int.</td>
			<td>Harris Uni-Core&#160;</td>
			<td>Diameter 2,5 mm</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Glass-bottom dish</td>
			<td>WPI</td>
			<td>Fluorodish FD 35-100</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Ultrasonic cleaner</td>
			<td>Branson Ultrasonics</td>
			<td>Branson 200</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Plasma cleaner</td>
			<td>Harrick Plasma</td>
			<td>PDC 32 G</td>
			<td>For small samples (35 dishes). A bigger version is also available</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Fibronectin from bovine plasma</td>
			<td>Sigma Aldrich</td>
			<td>F0895</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">PolyLysine grafted PEG (Pll-g-PEG)</td>
			<td>Susos</td>
			<td>PLL(20)-g[3.5]-PEG(5)</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Hoechst 33342</td>
			<td>Sigma Aldrich</td>
			<td>B2261</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Y27632</td>
			<td>TOCRIS</td>
			<td>1254</td>
			<td></td>
		</tr>
	</tbody>
</table>

study of cell migration in microfabricated channels

O método descrito aqui permite o estudo de migração celular sob confinamento numa dimensão. Ele baseia-se no uso de canais microfabricados, que impõem um fenótipo de células polarizadas por constrangimentos físicos. Uma vez que os canais internos, as células têm apenas duas possibilidades: seguir em frente ou para trás. Esta migração simplificada em que a direcionalidade é restrito facilita o rastreamento automático de células e extração de parâmetros quantitativos para descrever o movimento celular. Estes parâmetros incluem a velocidade da célula, mudanças de direcção e pausas durante o movimento. Microcanais também são compatíveis com a utilização de marcadores fluorescentes e são, portanto, adequados para estudar a localização de organelos e estruturas intracelulares durante a migração celular em alta resolução. Finalmente, a superfície dos canais podem ser funcionalizados com diferentes substratos, permitindo que o controlo das propriedades adesivas dos canais ou o estudo de haptotaxia. Em resumo, o sistema de here descrito destina-se a análise da migração de grandes números de células em condições em que tanto a geometria e a natureza bioquímica do ambiente são controlados, facilitando a normalização e reprodutibilidade de experiências independentes.

Em cada experimento, a superfície do PDMS revestido com uma molécula adaptado para o interesse do estudo. Figura 2 mostra os canais revestidos com uma molécula fluorescente, PLL-g-PEG, antes e após a lavagem (passo 2.4). Tal experiência permite o controlo da homogeneidade do revestimento dos canais. Após o carregamento da célula, microscopia de vídeo pode ser realizada a seguir a migração celular. Figura 3A mostra um exemplo de DC migrando em micro...

Watch this Scientific Journal Video about Study of Cell Migration in Microfabricated Channels at JoVE.com

Study of Cell Migration in Microfabricated Channels

Um método quantitativo para estudar a migração espontânea de células em um microambiente confinado unidimensional é descrito. Este método tira vantagem de canais microfabricados e pode ser utilizado para estudar a migração de grande número de células em condições diferentes nas experiências individuais.

Estudo da migração celular em Canais microfabricados

The method described here allows the study of cell migration under confinement in one dimension. It is based on the use of microfabricated channels, which ...

study-of-cell-migration-in-microfabricated-channels

Research

JoVE Journal

Bioengineering

11.8K visualizações.  Institut Curie.  Um método quantitativo para estudar a migração espontânea de células em um microambiente confinado unidimensional é descrito. Este método tira vantagem de canais microfabricados e pode ser utilizado para estudar a migração de grande número de células em condições diferentes nas experiências individuais. 

Vídeo: Study of Cell Migration in Microfabricated Channels

Microfabricated Platforms for Mechanically Dynamic Cell Culture

The ability to systematically probe in vitro cellular response to combinations of mechanobiological stimuli for tissue engineering, drug discovery or fundamental cell biology studies is limited by current bioreactor technologies, which cannot simultaneously apply a variety of mechanical stimuli to cultured cells. In order to address this issue, we have developed a series of microfabricated platforms designed to screen for the effects of mechanical stimuli in a high-throughput format. In this protocol, we demonstrate the fabrication of a microactuator array of vertically displaced posts on which the technology is based, and further demonstrate how this base technology can be modified to conduct high-throughput mechanically dynamic cell culture in both two-dimensional and three-dimensional culture paradigms.

In this protocol, we demonstrate the fabrication of a microactuator array of vertically displaced posts on which the technology is based, and how this base technology can be modified to conduct high-throughput mechanically dynamic cell culture in both two-dimensional and three-dimensional culture paradigms.

Plataformas microfabricated para cultura de células mecanicamente dinâmico

The ability to systematically probe in vitro cellular response to combinations of mechanobiological stimuli for tissue engineering, drug discovery or ...

Bioengenharia

Creating Two-Dimensional Patterned Substrates for Protein and Cell Confinement

Microcontact printing provides a rapid, highly reproducible method for the creation of well-defined patterned substrates.1 While microcontact printing can be employed to directly print a large number of molecules, including proteins,2 DNA,3 and silanes,4 the formation of self-assembled monolayers (SAMs) from long chain alkane thiols on gold provides a simple way to confine proteins and cells to specific patterns containing adhesive and resistant regions. This confinement can be used to control cell morphology and is useful for examining a variety of questions in protein and cell biology. Here, we describe a general method for the creation of well-defined protein patterns for cellular studies.5 This process involves three steps: the production of a patterned master using photolithography, the creation of a PDMS stamp, and microcontact printing of a gold-coated substrate. Once patterned, these cell culture substrates are capable of confining proteins and/or cells (primary cells or cell lines) to the pattern.
The use of self-assembled monolayer chemistry allows for precise control over the patterned protein/cell adhesive regions and non-adhesive regions; this cannot be achieved using direct protein stamping. Hexadecanethiol, the long chain alkane thiol used in the microcontact printing step, produces a hydrophobic surface that readily adsorbs protein from solution. The glycol-terminated thiol, used for backfilling the non-printed regions of the substrate, creates a monolayer that is resistant to protein adsorption and therefore cell growth.6 These thiol monomers produce highly structured monolayers that precisely define regions of the substrate that can support protein adsorption and cell growth. As a result, these substrates are useful for a wide variety of applications from the study of intercellular behavior7 to the creation of microelectronics.8
While other types of monolayer chemistry have been used for cell culture studies, including work from our group using trichlorosilanes to create patterns directly on glass substrates,9 patterned monolayers formed from alkane thiols on gold are straight-forward to prepare. Moreover, the monomers used for monolayer preparation are commercially available, stable, and do not require storage or handling under inert atmosphere. Patterned substrates prepared from alkane thiols can also be recycled and reused several times, maintaining cell confinement.10

Self-assembled monolayers (SAMs) formed from long chain alkane thiols on gold provide well-defined substrates for the formation of protein patterns and cell confinement. Microcontact printing of hexadecanethiol using a polydimethylsiloxane (PDMS) stamp followed by backfilling with a glycol-terminated alkane thiol monomer produces a pattern where protein and cells adsorb only to the stamped hexadecanethiol region.

Criando Two-Dimensional Substratos modelado para Confinamento de proteína e celular

Microcontact printing provides a rapid, highly reproducible method for the creation of well-defined patterned substrates.1  While microcontact printing ...

Electric Field-controlled Directed Migration of Neural Progenitor Cells in 2D and 3D Environments

Endogenous electric fields (EFs) occur naturally in vivo and play a critical role during tissue/organ development and regeneration, including that of the central nervous system1,2. These endogenous EFs are generated by cellular regulation of ionic transport combined with the electrical resistance of cells and tissues. It has been reported that applied EF treatment can promote functional repair of spinal cord injuries in animals and humans3,4. In particular, EF-directed cell migration has been demonstrated in a wide variety of cell types5,6, including neural progenitor cells (NPCs)7,8. Application of direct current (DC) EFs is not a commonly available technique in most laboratories. We have described detailed protocols for the application of DC EFs to cell and tissue cultures previously5,11. Here we present a video demonstration of standard methods based on a calculated field strength to set up 2D and 3D environments for NPCs, and to investigate cellular responses to EF stimulation in both single cell growth conditions in 2D, and the organotypic spinal cord slice in 3D. The spinal cordslice is an ideal recipient tissue for studying NPC ex vivo behaviours, post-transplantation, because the cytoarchitectonic tissue organization is well preserved within these cultures9,10. Additionally, this ex vivo model also allows procedures that are not technically feasible to track cells in vivo using time-lapse recording at the single cell level. It is critically essential to evaluate cell behaviours in not only a 2D environment, but also in a 3D organotypic condition which mimicks the in vivo environment. This system will allow high-resolution imaging using cover glass-based dishes in tissue or organ culture with 3D tracking of single cell migration in vitro and ex vivo and can be an intermediate step before moving onto in vivo paradigms.

This protocol demonstrates methods used to establish 2D and 3D environments in custom-designed electrotactic chambers, which can track cells in vivo/ex vivo using time-lapse recording at the single cell level, in order to investigate galvanotaxis/electrotaxis and other cellular responses to direct current (DC) electric fields (EFs).

Campo elétrico controlado de migração dirigida de células progenitoras neurais em ambientes 2D e 3D

Endogenous electric fields (EFs) occur naturally in vivo and play a critical role during tissue/organ development and regeneration, including that of the ...

Creating Adhesive and Soluble Gradients for Imaging Cell Migration with Fluorescence Microscopy

Cells can sense and migrate towards higher concentrations of adhesive cues such as the glycoproteins of the extracellular matrix and soluble cues such as growth factors. Here, we outline a method to create opposing gradients of adhesive and soluble cues in a microfluidic chamber, which is compatible with live cell imaging. A copolymer of poly-L-lysine and polyethylene glycol (PLL-PEG) is employed to passivate glass coverslips and prevent non-specific adsorption of biomolecules and cells. Next, microcontact printing or dip pen lithography are used to create tracks of streptavidin on the passivated surfaces to serve as anchoring points for the biotinylated peptide arginine-glycine-aspartic acid (RGD) as the adhesive cue. A microfluidic device is placed onto the modified surface and used to create the gradient of adhesive cues (100% RGD to 0% RGD) on the streptavidin tracks. Finally, the same microfluidic device is used to create a gradient of a chemoattractant such as fetal bovine serum (FBS), as the soluble cue in the opposite direction of the gradient of adhesive cues.

A method for the assembly of adhesive and soluble gradients in a microscopy chamber for live cell migration studies is described. The engineered environment combines antifouling surfaces and adhesive tracks with solution gradients and therefore allows one to determine the relative importance of guidance cues.

Criando Gradientes adesivas e solúvel para a migração celular Imaging com Microscopia de Fluorescência

Cells can sense and migrate towards higher concentrations of adhesive cues such as the glycoproteins of the extracellular matrix and soluble cues such as ...

Simultaneously Capturing Real-time Images in Two Emission Channels Using a Dual Camera Emission Splitting System: Applications to Cell Adhesion

Multi-color immunofluorescence microscopy to detect specific molecules in the cell membrane can be coupled with parallel plate flow chamber assays to investigate mechanisms governing cell adhesion under dynamic flow conditions. For instance, cancer cells labeled with multiple fluorophores can be perfused over a potentially reactive substrate to model mechanisms of cancer metastasis. However, multi-channel single camera systems and color cameras exhibit shortcomings in image acquisition for real-time live cell analysis. To overcome these limitations, we used a dual camera emission splitting system to simultaneously capture real-time image sequences of fluorescently labeled cells in the flow chamber. Dual camera emission splitting systems filter defined wavelength ranges into two monochrome CCD cameras, thereby simultaneously capturing two spatially identical but fluorophore-specific images. Subsequently, psuedocolored one-channel images are combined into a single real-time merged sequence that can reveal multiple target molecules on cells moving rapidly across a region of interest.

Dual camera emission splitting systems for two-color fluorescence microscopy generate real-time image sequences with exceptional optical and temporal resolution, a requirement of certain live cell assays including parallel plate flow chamber adhesion assays. When software is employed to merge images from simultaneously acquired emission channels, pseudocolored image sequences are produced.

Simultaneamente Capturar imagens em tempo real em dois canais de emissão Usando um sistema de separação, Dual Camera Emissão: Aplicações de Adesão Celular

Multi-color immunofluorescence microscopy to detect specific molecules in the cell membrane can be coupled with parallel plate flow chamber assays to ...

Using Microfluidics Chips for Live Imaging and Study of Injury Responses in Drosophila Larvae

Live imaging is an important technique for studying cell biological processes, however this can be challenging in live animals. The translucent cuticle of the Drosophila larva makes it an attractive model organism for live imaging studies. However, an important challenge for live imaging techniques is to noninvasively immobilize and position an animal on the microscope. This protocol presents a simple and easy to use method for immobilizing and imaging Drosophila larvae on a polydimethylsiloxane (PDMS) microfluidic device, which we call the 'larva chip'. The larva chip is comprised of a snug-fitting PDMS microchamber that is attached to a thin glass coverslip, which, upon application of a vacuum via a syringe, immobilizes the animal and brings ventral structures such as the nerve cord, segmental nerves, and body wall muscles, within close proximity to the coverslip. This allows for high-resolution imaging, and importantly, avoids the use of anesthetics and chemicals, which facilitates the study of a broad range of physiological processes. Since larvae recover easily from the immobilization, they can be readily subjected to multiple imaging sessions. This allows for longitudinal studies over time courses ranging from hours to days. This protocol describes step-by-step how to prepare the chip and how to utilize the chip for live imaging of neuronal events in 3rd instar larvae. These events include the rapid transport of organelles in axons, calcium responses to injury, and time-lapse studies of the trafficking of photo-convertible proteins over long distances and time scales. Another application of the chip is to study regenerative and degenerative responses to axonal injury, so the second part of this protocol describes a new and simple procedure for injuring axons within peripheral nerves by a segmental nerve crush.

Using Microfluidics Chips for Live Imaging and Study of Injury Responses in Drosophila Larvae

Drosophila larvae are an attractive model system for live imaging due to their translucent cuticle and powerful genetics. This protocol describes how to utilize a single-layer PDMS device, called the &#39;larva chip&#39; for live imaging of cellular processes within neurons of 3rd instar Drosophila larvae.

O uso de chips microfluídicos para Imagens ao vivo e estudo das respostas Lesão em<em&gt; Drosophila</em&gt; Larvas

Live imaging is an important technique for studying cell biological processes, however this can be challenging in live animals. The translucent cuticle of ...

Analysis of Cell Migration within a Three-dimensional Collagen Matrix

The ability to migrate is a hallmark of various cell types and plays a crucial role in several physiological processes, including&#160;embryonic development, wound healing, and immune responses. However, cell migration is also a key mechanism in cancer enabling these cancer cells to detach from the primary tumor to start metastatic spreading. Within the past years various cell migration assays have been developed to analyze the migratory behavior of different cell types. Because the locomotory behavior of cells markedly differs between a two-dimensional (2D) and three-dimensional (3D) environment it can be assumed that the analysis of the migration of cells that are embedded within a 3D environment would yield in more significant cell migration data. The advantage of the described 3D collagen matrix migration assay is that cells are embedded within a physiological 3D network of collagen fibers representing the major component of the extracellular matrix. Due to time-lapse video microscopy real cell migration is measured allowing the determination of several migration parameters as well as their alterations in response to pro-migratory factors or inhibitors. Various cell types could be analyzed using this technique, including lymphocytes/leukocytes, stem cells, and tumor cells. Likewise, also cell clusters or spheroids could be embedded within the collagen matrix concomitant with analysis of the emigration of single cells from the cell cluster/ spheroid into the collagen lattice. We conclude that the 3D collagen matrix migration assay is a versatile method to analyze the migration of cells within a physiological-like 3D environment.

Cell migration is a biological phenomenon that is involved in a plethora of physiological, such as wound healing and immune responses, and pathophysiological processes, like cancer. The 3D-collagen matrix migration assay is a versatile tool to analyze the migratory properties of different cell types within in a 3D physiological-like environment.

Análise da migração celular dentro de uma matriz de colagénio tridimensional

The ability to migrate is a hallmark of various cell types and plays a crucial role in several physiological processes, including&#160;embryonic ...

Concentric Gel System to Study the Biophysical Role of Matrix Microenvironment on 3D Cell Migration

The ability of cells to migrate is crucial in a wide variety of cell functions throughout life&#160;from embryonic development and wound healing&#160;to tumor and cancer metastasis. Despite intense research efforts, the basic biochemical and biophysical principles of cell migration are still not fully understood, especially in the physiologically relevant three-dimensional (3D) microenvironments. Here, we describe an in vitro assay designed to allow quantitative examination of 3D cell migration behaviors. The method exploits the cell&#8217;s mechanosensing ability and propensity to migrate into previously unoccupied extracellular matrix (ECM). We use the invasion of highly invasive breast cancer cells, MDA-MB-231, in collagen gels as a model system. The spread of cell population and the migration dynamics of individual cells over weeks of culture can be monitored using live-cell imaging and analyzed to extract spatiotemporally-resolved data. Furthermore, the method is easily adaptable for diverse extracellular matrices, thus offering a simple yet powerful way to investigate the role of biophysical factors in the microenvironment on cell migration.

The mechanical properties and microstructure of the extracellular matrix strongly affect 3D migration of cells. An in vitro method to study the spatiotemporal cell migration behavior in biophysically variable environments, at both population and individual cell levels, is described.

Sistema de Gel Concentric para estudar o papel Biofísica da Matrix Microenvironment sobre a migração celular 3D

The ability of cells to migrate is crucial in a wide variety of cell functions throughout life&#160;from embryonic development and wound healing&#160;to ...

Distinctive Capillary Action by Micro-channels in Bone-like Templates can Enhance Recruitment of Cells for Restoration of Large Bony Defect

Without an active, thriving cell population that is well-distributed and stably anchored to the inserted template, exceptional bone regeneration does not occur. With conventional templates, the absence of internal micro-channels results in the lack of cell infiltration, distribution, and inhabitance deep inside the templates. Hence, a highly porous and uniformly interconnected trabecular-bone-like template with micro-channels (biogenic microenvironment template; BMT) has been developed to address these obstacles. The novel BMT was created by innovative concepts (capillary action) and fabricated with a sponge-template coating technique. The BMT consists of several structural components: inter-connected primary-pores (300-400 &#181;m) that mimic pores in trabecular bone, micro-channels (25-70 &#181;m) within each trabecula, and nanopores (100-400 nm) on the surface to allow cells to anchor. Moreover, the BMT has been documented by mechanical test study to have similar mechanical strength properties to those of human trabecular bone (~3.8 MPa)12.
The BMT exhibited high absorption, retention, and habitation of cells throughout the bridge-shaped (&#928;) templates (3 cm height and 4 cm length). The cells that were initially seeded into one end of the templates immediately mobilized to the other end (10 cm distance) by capillary action of the BMT on the cell media. After 4 hr, the cells homogenously occupied the entire BMT and exhibited normal cellular behavior. The capillary action accounted for the infiltration of the cells suspended in the media and the distribution (active migration) throughout the BMT. Having observed these capabilities of the BMT, we project that BMTs will absorb bone marrow cells, growth factors, and nutrients from the periphery under physiological conditions.
The BMT may resolve current limitations via rapid infiltration, homogenous distribution and inhabitance of cells in large, volumetric templates to repair massive skeletal defects.

A step-by-step generic process to create a bone-like template with engineered micro-channels is presented. High absorption and retention capabilities of the template are demonstrated by capillary action via micro-channels.

Modelos distintivo ação capilar por micro-canais em Osso-como pode aumentar o recrutamento de células para a Restauração da Grande Bony Defeito

Without an active, thriving cell population that is well-distributed and stably anchored to the inserted template, exceptional bone regeneration does not ...

Preparation of 3D Collagen Gels and Microchannels for the Study of 3D Interactions In Vivo

Historically, most cellular processes have been studied in only 2 dimensions. While these studies have been informative about general cell signaling mechanisms, they neglect important cellular cues received from the structural and mechanical properties of the local microenvironment and extracellular matrix (ECM). To understand how cells interact within a physiological ECM, it is important to study them in the context of 3 dimensional assays. Cell migration, cell differentiation, and cell proliferation are only a few processes that have been shown to be impacted by local changes in the mechanical properties of a 3-dimensional ECM. Collagen I, a core fibrillar component of the ECM, is more than a simple structural element of a tissue. Under normal conditions, mechanical cues from the collagen network direct morphogenesis and maintain cellular structures. In diseased microenvironments, such as the tumor microenvironment, the collagen network is often dramatically remodeled, demonstrating altered composition, enhanced deposition and altered fiber organization. In breast cancer, the degree of fiber alignment is important, as an increase in aligned fibers perpendicular to the tumor boundary has been correlated to poorer patient prognosis1. Aligned collagen matrices result in increased dissemination of tumor cells via persistent migration2,3. The following is a simple protocol for embedding cells within a 3-dimensional, fibrillar collagen hydrogel. This protocol is readily adaptable to many platforms, and can reproducibly generate both aligned and random collagen matrices for investigation of cell migration, cell division, and other cellular processes in a tunable, 3-dimensional, physiological microenvironment.

Preparation of 3D Collagen Gels and Microchannels for the Study of 3D Interactions In Vivo

Collagen is a core component of the ECM, and provides essential cues for several cellular processes ranging from migration to differentiation and proliferation. Provided here is a protocol for embedding cells within 3D collagen hydrogels, and a more advanced technique for generating randomized or aligned collagen matrices using PDMS microchannels.

Preparação de 3D colágeno Géis e microcanais para o estudo das interações 3D<em&gt; In Vivo</em

Historically, most cellular processes have been studied in only 2 dimensions.  While these studies have been informative about general cell signaling ...

Methods Article

Estudo da migração celular em Canais microfabricados