As linhas de células de próstata são gentilmente cedido pelo Dr. Ling-Yu Wang e Dr. Hsing-Jien Kung no Centro de Câncer, UC Davis. Este projecto é financiado pelo NIH galvanotaxis concessão 4R33AI080604.

1. A cultura da próstata Células <ol><li> Cultura A PRN-1-1 e PNT2 próstata células em placas de 100 mm de cultura em meio RPMI 1640 suplementado com 10% de FBS e Antibiótico-antimicótico a 37 ° C com 5% de CO 2. Refrescar o meio de cultura todos os dias até as células atingirem a confluência de 80% para as experiências galvanotaxis. </li></ol> 2. Montagem Galvanotaxis Chambers <ol><li> Montagem câmaras inferiores <ol><li> Wipe uma câmara galvanotaxis plástico com 2-propanol. Aplicar o selante de silicone de grau marinho em torno das aberturas circulares no lado inferior de uma câmara com uma seringa e fixar uma grande lamela (Figura 1). Use a parte de trás de um aplicador de algodão para empurrar para baixo a lamela e limpe o excesso de cola com cotonetes. As aberturas circulares permitir que a forma e a corrente eléctrica para fluir sobre as células localizadas entre os dois reservatórios internos médios. </li><li> Corte uma pequena lamela para fazer 6 mm x 25 espaçadores mm com um marcador de ponta de diamante. </li><li> Vire a câmara. Aplicar duas bandas da cola de silicone com uma seringa e / ou uma espátula de metal para criar uma superfície de canal x 25 mm 10 mm para a fixação das células entre as duas aberturas circulares no fundo de vidro. Cole dois pedaços de vidro espaçador entre as duas aberturas circulares. Use a parte de trás dos aplicadores de algodão para empurrar para baixo os espaçadores e limpe o excesso de cola com cotonetes e / ou palitos de algodão. </li><li> Seca-se a câmara durante 24 horas até que a cola de silicone é curado. Embeber a câmara em água destilada durante a noite para remover o resíduo de ácido acético a partir da cola. Seque a câmara para uso imediato, ou armazenar a câmara para uso posterior em um recipiente limpo. <img alt="Figura 1" fo:content-width="5in" src="/files/ftp_upload/51973/51973fig1highres.jpg" width="500" /> Figura 1: Assembleia da câmara na parte inferior galvanotaxis. A) Um grande lamela está ligado ao fundo de uma câmara de limpeza. B) Two peças de espaçadores de vidro são coladas entre as duas aberturas circulares para criar a 10 mm x 25 milímetros canal para as células para anexar. </li></ol></li><li> Semeando células nas câmaras galvanotaxis <ol><li> Prepare o número de exigir câmaras galvanotaxis necessários para o experimento. Cada linha ou tratamento com células requer uma única câmara galvanotaxis. Limpe as câmaras galvanotaxis com 2-propanol. Lavam-se as câmaras estéreis com PBS 3 vezes e verificar o fluxo de líquido entre as duas aberturas circulares nas câmaras. </li><li> Coloque as câmaras em pratos de cultura de células estéril e permitir que se equilibre a 37 ° C durante 15 min. Separar as células da próstata a partir da sua placa de cultura, utilizando 5 ml de 0,25% de Tripsina-EDTA a 37 ° C durante 5 min. Neutraliza-se a tripsina-EDTA, com 5 ml de 10% de FBS em PBS. </li><li> Transferem-se as células para tubos de 15 ml e centrifugar as células durante 5 min a 200 x g, 37 ° C. Aspirar o sobrenadante e ressuspender as células em 1 ml de meio de cultura. </li><li> Pegue 20 μl de solução de células para carregar para uma câmara de contagem e calcular o número de células. Ajustar a concentração de células a 8 x 10 4 células / ml com meio de cultura. </li><li> Tome as câmaras galvanotaxis fora da 37 ° C incubadora. Semente de 350 ul da suspensão de células em cada câmara. </li><li> Incubar as células nas câmaras durante a noite em placas de cultura com Kimwipe molhado ou em uma câmara de humidade na incubadora a 37 ° C com 5% de CO 2. </li></ol></li></ol><img alt="Figura 2" fo:content-width="5in" src="/files/ftp_upload/51973/51973fig2highres.jpg" width="500" /> Figura 2:. Semear as células à câmara A câmara inferior é seco e limpo células A) da próstata são tripsinizadas, contadas e transferido para a câmara e incubou-se durante a noite B) Uma lamela superior está ligada para vedar a câmara antes de filmar... <ol start="3"><li> Assembling os melhores câmaras <ol><li> Monte a câmara superior antes das filmagens. O microscópio só pode acomodar imagiologia de uma única câmara de galvanotaxis de uma só vez. Aquecer-se 10 ml de meio de cultura a 37 ° C para cada câmara galvanotaxis. Transferir uma câmara galvanotaxis das incubadoras para a 37 ° C placa de aquecimento. </li><li> Lavar as células com meio de cultura para remover as células não ligadas. Deixar a 400 ul de meio na câmara. Use uma seringa para aplicar alta graxa de vácuo no topo de ambos os espaçadores de vidro. </li><li> Adicionar uma pequena lamela para vedar a câmara. Pressione suavemente a lamela com a parte de trás de um aplicador de algodão. Limpe o meio excesso com cotonetes. </li><li> Seque a superfície do vidro e aplicar vácuo elevado graxa para vedar o espaço entre a lamela e a câmara. Use uma espátula de metal para espalhar a graxa. Adicionar 4 ml de meio de cultura para os reservatórios interno e verificar o fluxo de líquido entre os reservatórios. </li></ol></li><li> Faça agarpontes <ol><li> Corte um par de 2 polegadas tubo longo PVC (503/16 ID x 16/05 x 16/01 OD Wall), virar e inseri-los em um copo de 100 ml. </li><li> Medir 200 mg de Bacto-Agar e adicioná-lo num frasco de 50 ml com 10 ml de meio de cultura para fazer 2% de gel de agar. Micro-ondas por 30 segundos. Carregar o gel de agar para o tubo de plástico com uma pipeta de transferência. Deixar as pontes de agar à temperatura ambiente durante 10 minutos para solidificar o agar. </li><li> Adicionar 2 ml de meio de cultura para os reservatórios exteriores da câmara galvanotaxis. Inserir as pontes agar para os reservatórios interno e externo médio para conduzir a corrente. </li></ol></li></ol><img alt="Figura 3" fo:content-width="3.5in" src="/files/ftp_upload/51973/51973fig3highres.jpg" width="350" /> Figura 3:. Filmar as células na câmara de um diagrama para demonstrar a montagem final da câmara galvanotaxis. A câmara é completamente selado com graxa alto vácuo. O meio é adicionado to encher os reservatórios, e duas pontes de agar são inseridos dentro da câmara. Em seguida, a câmara de galvanotaxis é transferida para o estágio de microscópio e os eléctrodos estão ligados para aplicar o campo eléctrico. Vista lateral da câmara de galvanotaxis montado é mostrado para demonstrar que a corrente eléctrica flui através das células através das pontes de agar e o espaço entre o vidro de cobertura. 3. tempo-lapso <ol><li> Ligar a câmara ambiental a 37 ° C com 5% de CO 2 no ar circulante 2 h antes da imagiologia. </li><li> Ligue o microscópio e iniciar o software de aquisição de imagem. Calibrar o estágio do microscópio e selecione a objetiva de 10X. </li><li> Transfira as câmaras galvanotaxis ao palco microscópio, fixe a câmara com fita adesiva e concentrar-se nas células. Insira os eletrodos galvanotaxis para os reservatórios exteriores com cátodo no lado direito. Fixar o cabo e com os eléctrodos de fita. </li><li> Ligue o bo poderx para aplicar um campo eléctrico para a câmara. Medir a tensão de saída com o voltímetro através da câmara para atingir 2,5 volts para a câmara longo de 25 mm (100 mV / mm). Manter a intensidade do campo durante a experiência, ajustando a corrente de saída. </li><li> Selecione 10 pontos em toda a câmara de filmar no software para gerar dez filmes de lapso de tempo. Configurar as condições de aquisição em 10 minutos de intervalo, durante 2 horas. </li><li> Iniciar filmagens e ajustar a corrente de saída, conforme necessário. </li><li> No final da experiência, remover a câmara da fase e fixar as células com 95% de álcool. Quebre aberto a câmara com uma lâmina de barbear para limpar e reutilizá-lo. </li></ol> 4. Quantificação do Galvanotaxis <ol><li> Gire os filmes lapso de tempo e re-orientar o cátodo para o início das imagens. Exportar os filmes para o software de rastreamento de celular. </li><li> Controlar manualmente a (x-y,) posição de 10-20 células em cada ponto de tempo a partir de cada filme (Figura 4 A, B).As distâncias de migração e os ângulos em relação à direcção norte-sul, a mesma orientação do campo elétrico, será calculado no software de rastreamento de celular (Figura 4C). NOTA: A velocidade de migração média é convertida a partir da distância total migração e tempo total de filmagens. A direccionalidade é convertido a partir dos ângulos em relação ao valor de co-seno. Se as células migram com direcionalidade aleatória, a média de cosseno líquido será próximo de zero. Se as células migram directamente para o cátodo, o valor de co-seno será uma. Se as células migram directamente para o ânodo, o valor de co-seno será -1. </li></ol><img alt="Figura 4" fo:content-width="4in" src="/files/ftp_upload/51973/51973fig4highres.jpg" width="400" /> Figura 4: rastreamento de celular para medir a direcionalidade A) Sobreposição das linhas de monitoramento com imagens das células.. Os (x, y) as posições das células são manually rastreados nos filmes de lapso de tempo. . Se as células migram aleatoriamente, o cosseno médio é próximo de zero B) No entanto, se as células migram para o cátodo ou o ânodo, o valor do cosseno médio está próximo de + (cátodo) ou -. (Ânodo) 1,0 C ) A direccionalidade é apresentado pelo valor de co-seno, a qual é convertida a partir dos ângulos de migração (θ). A co-seno (θ) é igual à razão entre a distância A (a distância de migração) a distância b (a distância projectada para a direcção do campo eléctrico). <ol start="3"><li> Salve as medições. Importar os dados para uma aplicação de base de dados para calcular os resultados combinados. </li><li> Exportar os dados combinados de média velocidade de migração e valor médio de co-seno de uma planilha para plotar os gráficos de barras (Figura 5). </li></ol>

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R., Nuccitelli, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Imposition+of+a+physiologic+DC+electric+field+alters+the+migratory+response+of+human+keratinocytes+on+extracellular+matrix+molecules.">Imposition of a physiologic DC electric field alters the migratory response of human keratinocytes on extracellular matrix molecules.</a> J Invest Dermatol. 106 (4), 642-646 (1996).</li><li>Feng, J. F., 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=Guided+migration+of+neural+stem+cells+derived+from+human+embryonic+stem+cells+by+an+electric+field.">Guided migration of neural stem cells derived from human embryonic stem cells by an electric field.</a> Stem Cells. 30 (2), 349-355 (2012).</li><li>Mukerjee, E. V., Isseroff, R. R., Nuccitelli, R., Collins, S. D., Smith, R. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microneedle+array+for+measuring+wound+generated+electric+fields.">Microneedle array for measuring wound generated electric fields.</a> Conf Proc IEEE Eng Med Biol Soc. 1, 4326-4328 (2006).</li><li>Nuccitelli, R., Nuccitelli, P., Li, C., Narsing, S., Pariser, D. M., Lui, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+electric+field+near+human+skin+wounds+declines+with+age+and+provides+a+noninvasive+indicator+of+wound+healing.">The electric field near human skin wounds declines with age and provides a noninvasive indicator of wound healing.</a> Wound Rep. and Reg. 19, 645-655 (2011).</li></ol>

The authors have nothing to disclose.

A análise da resposta galvanotaxis de uma célula tem sido um importante indicador funcional para muitos migratório celular ou crescimento processa 27, 28. Aqui usamos uma câmara feito por encomenda com superfície de vidro para filmar duas linhas de células da próstata. Estas linhas de células demonstraram diferentes graus de galvanotaxis, e especula-se que a localização intracelular ou da activação das proteínas de mediar galvanotaxis pode ser interferido durante o processo de geração de linhas...

Campos eléctricos endógenos são detectados em vários tecidos, tais como pele, 1, 32, 33 e 2 cérebro. O campo eléctrico fisiológico serve funções biológicas particulares, incluindo a orientação desenvolvimento embrionário 3, 4, guiando o crescimento de processos neuronais 5, 6 e promoção do epitélio da córnea e o fechamento da ferida 1, 7. In vitro, a aplicação de um campo eléctrico de corrente directa para células cultivadas imita o campo elétrico fisiológico e induz a migração de células direcional, ou galvanotaxis. Galvanotaxis foi estudado em fibroblastos 8, queratinócitos de peixe 9, epitelial da córnea humana e queratinócitos 10-12, 13 linfócitos, 2, neuroblastos e as células progenitoras neuronais 14. Quando exposta ao campo aplicado, a maioria das células estudadas migrar direccionalmente para a catódica (-) pólo. No entanto, várias células cancerosas, incluindo altamente metastáticocélulas de cancro da mama humano e a linha de células de cancro da próstata humano PC-3M, mover-se para a anódica (+) pólo 15, 16. Vários mecanismos são propostos para mediar galvanotaxis ou para explicar a capacidade das células para detectar o campo eléctrico, incluindo a activação de receptores EGF 12, o canal de sódio epitelial 17, PI3K e PTEN 18, e liberação de íons cálcio 15, 19. O mecanismo ainda não é totalmente compreendido, e é possível que múltiplas vias de sinalização estão envolvidos em galvanotaxis. O método galvanotaxis 2-dimensional demonstramos aqui é útil para caracterizar a migração direccional de aderente, células móveis, quer para controlar a migração de células individuais 10, 12, 17 ou migração de uma folha de células confluentes 18, 20. Esta técnica é uma modificação Peng e Jaffe 21, e Nishimura et al. 10 com câmaras de PVC feito por encomenda, claras, com coversl removívelips permitindo a recuperação de células fácil depois galvanotaxis para análise secundária, como a imagem de imuno-fluorescência. A superfície de vidro dos câmaras galvanotaxis óptico é compatível, o que permite que a película de alta ampliação e com células fluorescentemente marcado. Ele também permite que o desenho experimental com a modificação da superfície de vidro, como a alteração do revestimento de superfície ou encargos. Espaçadores feitos de uma lamela No. são usados ​​nas câmaras para minimizar o fluxo de corrente sobre as células; Por conseguinte, o aquecimento por efeito de Joule, o que é proporcional ao quadrado da intensidade da corrente, não sobreaquecer as células durante a experiência. As pontes que ligam agar evitar o contato direto dos eletrodos com as células e evitar a mudança do meio de pH ou concentração de íons durante galvanotaxis. Duas linhas de células de próstata humana não tumorigénicas foram examinadas quanto à sua resposta galvanotaxis neste estudo. Os PRN-1-1 22 e PNT2 23 são ambos SV40-imortalizada, de crescimento de linhas celulares dependentes de factores expressando os marcadores epiteliais citoqueratina 5, 8, 18 e 19 com pouca ou nenhuma expressão do antigénio específico da próstata (PSA). Ambas as linhas celulares manter a morfologia poligonal de células epiteliais normais, mas cromossoma anormalidade foi observada no cariótipo 22, 24. Embora PRN-1-1 e PNT2 partes comportamentos semelhantes na maior parte das experiências, eles mostram diferenças na formação de estrutura e nos ácinos galvanotaxis. Em uma matriz 3-D, Matrigel, os PRN-1-1 células formam estruturas acinares ocas com lumens que assemelham-se a próstata normal de tecido glandular 25. No entanto, as células PNT2 formar esferóides sólidos sem um lúmen ou epitélio polarizado 26. As células PRN-1-1 também demonstram uma resposta mais elevada do que a galvanotactic PNT2 no estudo corrente. A correlação entre a formação de estrutura e acinar galvanotaxis em PRN-1-1 sugere que os sinais galvanotactic pode desempenhar um papel na organização do prmovimentos dos tecidos glandulares ostate em resposta a campos elétricos endógenos, e fornece mais características de discriminar entre estes 2 linhas celulares.

<table><tbody><tr><td colspan="4">&lt;strong&gt;Cells&lt;/strong&gt;</td></tr><tr><td>pRNS-1-1 prostate cells</td><td></td><td></td><td>Lee, &lt;em&gt;et al.&lt;/em&gt; (1994)</td></tr><tr><td>PNT2 prostate cells</td><td>Sigma-Aldrich</td><td>95012613-1VL</td><td>Berthon, &lt;em&gt;et al.&lt;/em&gt; (1995)</td></tr><tr><td colspan="4">&lt;strong&gt;Medium and solutions&lt;/strong&gt;</td></tr><tr><td>RPMI 1640 medium&amp;nbsp;</td><td>Invitrogen</td><td>11875-093</td><td>warm up to 37 &amp;deg;C before use</td></tr><tr><td>Fetal Bovine Serum - Premium</td><td>Atlanta Biologicals</td><td>S11150</td><td>10% in PBS, warm up to 37 &amp;deg;C before use</td></tr><tr><td>Antibiotic-Antimycotic (100x)</td><td>Life Technologies</td><td>15240</td><td>add 5 ml to 500 ml medium</td></tr><tr><td>2-propanol</td><td>VWR</td><td>BDH1133-5GL</td><td></td></tr><tr><td>PBS</td><td>-</td><td>-</td><td>137 mM NaCl, 2.7 mM KCl, 4.3 mM Na&lt;sub&gt;2&lt;/sub&gt;HPO&lt;sub&gt;4&lt;/sub&gt; and 1.5 mM KH&lt;sub&gt;2&lt;/sub&gt;PO&lt;sub&gt;4&lt;/sub&gt; in 1,000 ml of H&lt;sub&gt;2&lt;/sub&gt;O, pH to 7.4 and autoclaved, warm up to 37 &amp;deg;C before use</td></tr><tr><td>0.25% Trypsin-EDTA&amp;nbsp;</td><td>Invitrogen</td><td>25200-056</td><td>warm up to 37 &amp;deg;C before use, treat cells for 3-5 min at 37 &amp;deg;C</td></tr><tr><td colspan="4">&lt;strong&gt;Galvanotaxis device&lt;/strong&gt;</td></tr><tr><td>Galvanotaxis chambers</td><td>Precision Plastics Inc, CA</td><td></td><td>Custom-designed (1/4&quot; x 2&quot; x 3.5&quot;), non-toxic, clear PVC chambers. Please contact the authors for the design specs.</td></tr><tr><td>Galvanotaxis electrodes</td><td>UCD electric shop</td><td></td><td>platinum coiled electrodes with flexable cords</td></tr><tr><td>Galvanotaxis power box</td><td>Substrate Engineering, CA</td><td></td><td>custom-designed DC power output with voltmeter</td></tr><tr><td>Microscope Cover Glass, Large, 45 x 50 mm, No. 1.5</td><td>Fisher</td><td>12-544-F</td><td></td></tr><tr><td>Microscope Cover Glass, small, 25 x 25 mm, No. 1</td><td>ThermoScientific</td><td>3307</td><td></td></tr><tr><td>Diamond point marker</td><td>ThermoScientific</td><td>750</td><td></td></tr><tr><td>Marine grade silicon sealer, clear</td><td>3M</td><td>051135-08019</td><td></td></tr><tr><td>High vacuum grease</td><td>Dow Corning</td><td>2021846-0807</td><td></td></tr><tr><td>6 ml syringe</td><td>Fisher Scientific</td><td>05-561-64</td><td></td></tr><tr><td>Nichiryo Syringe, 1.5 ml</td><td>Nichiryo</td><td>SG-M</td><td></td></tr><tr><td>Cotton applicators</td><td>Purtian Medical Products</td><td>806-WC</td><td></td></tr><tr><td>Qtips</td><td>Johnson &amp;amp; Johnson</td><td>729389</td><td></td></tr><tr><td>Nalgene 180 PVC tubing&amp;nbsp;</td><td>Nalgene</td><td>8000-9030</td><td>503/16 ID x 5/16 OD x 1/16 Wall</td></tr><tr><td>Bacto-Agar</td><td>Difco</td><td>0140-01</td><td>make 2% agar solution</td></tr><tr><td>Razor Blade</td><td>Personna</td><td>74-0001</td><td></td></tr><tr><td colspan="4">&lt;strong&gt;Equipments and Software&lt;/strong&gt;</td></tr><tr><td>Benchtop Centrifuge</td><td>Eppendorf</td><td>5810R</td><td>operated with an A-4-62 rotor</td></tr><tr><td>Cellometer Auto T4</td><td>Nexcelom</td><td>Auto T4</td><td></td></tr><tr><td>Cellometer counting chambers</td><td>Nexcelom</td><td>CHT4-SD100-002</td><td>load 20 &amp;#956;l cell solutions to count</td></tr><tr><td>Culture Temp Warming plate</td><td>Bel-Art Scienceware</td><td>370150000</td><td>to keep the galvanotaxis chambers at 37 &amp;deg;C&amp;nbsp;</td></tr><tr><td>Eclipse TE-2000 microscope with motorized stage and environmental chamber</td><td>Nikon</td><td></td><td></td></tr><tr><td>Plan Fluor 10X/0.30 objective len</td><td>Nikon</td><td></td><td></td></tr><tr><td>Retiga EX CCD camera&amp;nbsp;</td><td>Qimaging</td><td></td><td>Cooled CCD camara, mono-color, 12-bit</td></tr><tr><td>Compressed air with 5% CO&lt;sub&gt;2&lt;/sub&gt;</td><td>Airgas</td><td></td><td>special order</td></tr><tr><td>Volocity 6.3</td><td>PerkinElmer</td><td></td><td>Image acquiring software</td></tr><tr><td>Improvision OpenLab 5.5.2</td><td>PerkinElmer</td><td></td><td>Cell tracking software and customized to measure migration angles</td></tr><tr><td>FileMaker Pro Advanced, 8.0</td><td>FileMaker</td><td></td><td></td></tr><tr><td>Microsoft Excel 2008 for Mac</td><td>Microsoft</td><td></td><td></td></tr></tbody></table>

utilizing custom-designed galvanotaxis chambers to study directional migration of prostate cells

O campo eléctrico fisiológico serve funções biológicas específicas, tais como dirigir a migração de células no desenvolvimento embrionário, crescimento neuronal e reparação epitelial. A aplicação de um campo eléctrico de corrente directa para células cultivadas in vitro, induz a migração de células direccional, ou galvanotaxis. O método galvanotaxis 2-dimensional demonstramos aqui é modificado com feito por encomenda poli (cloreto de vinilo) (PVC) câmaras, superfície de vidro, eléctrodos de platina e a utilização de uma fase motorizada no qual as células são criadas imagens. As câmaras de PVC e eletrodos de platina apresentam baixa toxicidade e são acessíveis e re-utilizável. A superfície de vidro e a platina motorizada microscópio melhorar a qualidade das imagens e permitir a possibilidade de alterar a superfície do vidro e tratamentos para as células. Filmamos o galvanotaxis de dois, linhas de células não-tumorais imortalizada com SV40 próstata, PRN-1-1 e PNT2. Estas duas linhas de células mostram velocidades de migração semelhantes e ambos migrar em direcçãocátodo, mas mostram um grau diferente de direcionalidade em galvanotaxis. Os resultados obtidos através deste protocolo sugerem que os PRN-1-1 e as linhas de células PNT2 podem ter diferentes características intrínsecas que governam as suas respostas migratórias direcionais.

Duas linhas de células da próstata (PRN-1-1 e PNT2) foram investigadas com este método. As células em ambas as linhas de migrar a velocidades similares de 1,0 +/- 0,3 micra / min ao longo de 2 horas (Figura 5A). No entanto, o direccionamento para o campo eléctrico é de 0,7 +/- 0,3 para a PRN-linha 1-1, e 0,2 +/- 0,8 para a linha PNT2 (Figura 5B). Os resultados mostram uma diferença significativa na galvanotaxis destas duas linhas celulares (p &lt;0,01, as células foram rastreado...

Watch this Scientific Journal Video about Utilizing Custom-designed Galvanotaxis Chambers to Study Directional Migration of Prostate Cells at JoVE.com

Utilizing Custom-designed Galvanotaxis Chambers to Study Directional Migration of Prostate Cells

We present a method to apply a physiological electric field to migrating, immortalized prostate cells in a custom-made galvanotaxis chamber. Using this method, we demonstrate that 2 lines of non-tumorigenic prostate cells demonstrate different degrees of migration directionality in the field.

Utilizando a pedido de clientes Galvanotaxis Chambers para Estudar Direcional migração das células da próstata

The physiological electric field serves specific biological functions, such as directing cell migration in embryo development, neuronal outgrowth and ...

utilizing-custom-designed-galvanotaxis-chambers-to-study-directional

Research

JoVE Journal

Biology

9.1K visualizações.  University of California, Davis. We present a method to apply a physiological electric field to migrating, immortalized prostate cells in a custom-made galvanotaxis chamber. Using this method, we demonstrate that 2 lines of non-tumorigenic prostate cells demonstrate different degrees of migration directionality in the field.

Vídeo: Utilizing Custom-designed Galvanotaxis Chambers to Study Directional Migration of Prostate Cells

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 ...

Bioengenharia

Evaluation of Cancer Stem Cell Migration Using Compartmentalizing Microfluidic Devices and Live Cell Imaging

In the last 40 years, the United States invested over 200 billion dollars on cancer research, resulting in only a 5% decrease in death rate. A major obstacle for improving patient outcomes is the poor understanding of mechanisms underlying cellular migration associated with aggressive cancer cell invasion, metastasis and therapeutic resistance1. Glioblastoma Multiforme (GBM), the most prevalent primary malignant adult brain tumor2, exemplifies this difficulty. Despite standard surgery, radiation and chemotherapies, patient median survival is only fifteen months, due to aggressive GBM infiltration into adjacent brain and rapid cancer recurrence2. The interactions of aberrant cell migratory mechanisms and the tumor microenvironment likely differentiate cancer from normal cells3. Therefore, improving therapeutic approaches for GBM require a better understanding of cancer cell migration mechanisms. Recent work suggests that a small subpopulation of cells within GBM, the brain tumor stem cell (BTSC), may be responsible for therapeutic resistance and recurrence. Mechanisms underlying BTSC migratory capacity are only starting to be characterized1,4.
Due to a limitation in visual inspection and geometrical manipulation, conventional migration assays5 are restricted to quantifying overall cell populations. In contrast, microfluidic devices permit single cell analysis because of compatibility with modern microscopy and control over micro-environment6-9.
We present a method for detailed characterization of BTSC migration using compartmentalizing microfluidic devices. These PDMS-made devices cast the tissue culture environment into three connected compartments: seeding chamber, receiving chamber and bridging microchannels. We tailored the device such that both chambers hold sufficient media to support viable BTSC for 4-5 days without media exchange. Highly mobile BTSCs initially introduced into the seeding chamber are isolated after migration though bridging microchannels to the parallel receiving chamber. This migration simulates cancer cellular spread through the interstitial spaces of the brain. The phase live images of cell morphology during migration are recorded over several days. Highly migratory BTSC can therefore be isolated, recultured, and analyzed further. 
Compartmentalizing microfluidics can be a versatile platform to study the migratory behavior of BTSCs and other cancer stem cells. By combining gradient generators, fluid handling, micro-electrodes and other microfluidic modules, these devices can also be used for drug screening and disease diagnosis6. Isolation of an aggressive subpopulation of migratory cells will enable studies of underlying molecular mechanisms.

A compartmentalizing microfluidic device for investigating cancer stem cell migration is described. This novel platform creates a viable cellular microenvironment and enables microscopic visualization of live cell locomotion. Highly motile cancer cells are isolated to study molecular mechanisms of aggressive infiltration, potentially leading to more effective future therapies.

Avaliação do Câncer de Migração Stem Cell Usando compartimentar dispositivos microfluídicos e imagens de células vivas

In the last 40 years, the United States invested over 200 billion dollars on cancer research, resulting in only a 5% decrease in death rate. A major ...

Medicina

Migratory Behavior of Cells Generated in Ganglionic Eminence Cultures

Migration of cells is a common process that leads to the development and maturation of the vertebrate central nervous system (Hatten, '99). The cerebral cortex consists of two basic neuronal types: excitatory and inhibitory. These cells arise in distinct areas and migrate into the cortex along different routes (Pearlman et al., '98). Inhibitory interneurons migrate tangentially from subcortical sources, mostly from different regions of the ganglionic eminences (Gelman et al., '09; Xu et al., '04). Their movement requires precise spatiotemporal control imposed by environmental cues, to allow for the establishment of proper cytoarchitecture and connectivity in the cerebral cortex (Caviness &amp; Rakic, '78; Hatten, '90; Rakic, '90). To study the migratory behavior of cells generated in proliferative zones of the ganglionic eminences (GE) in newborn ferrets in vitro we used a 3 dimensional culture arrangement in a BD Matrigel Matrix. The culture setup consisted of two GE explants and a source of tested proteins extracted from the cerebral cortex and adsorbed on fluorescent latex Retrobeads IX positioned between the explants (Hasling et al., '03; Riddle et al., '97). After 2-3 days of culture, the cells start to appear at the edge of the explant showing a propensity to leave the tissue in a radial direction. Live imaging allowed observation of migratory patterns without the necessity of labeling or marking the cells. When exposed to fractions of the protein extract obtained from isochronic ferret cortex, the GE cells displayed different behaviors as judged by quantitative kinetic analysis of individual moving cells.

Time lapse imaging of 3D tissue culture allows studying migratory behavior of individual cells originating from ganglionic eminence in reaction to fractionated protein extract from cerebral cortex.

Comportamento migratório de células geradas em culturas Eminence ganglionares

Migration of cells is a common process that leads to the development and maturation of the vertebrate central nervous system (Hatten, '99). The cerebral ...

Neurociência

Live-Cell Imaging Assays to Study Glioblastoma Brain Tumor Stem Cell Migration and Invasion

Glioblastoma (GBM) is an aggressive brain tumor that is poorly controlled with the currently available treatment options. Key features of GBMs include rapid proliferation and pervasive invasion into the normal brain. Recurrence is thought to result from the presence of radio- and chemo-resistant brain tumor stem cells (BTSCs) that invade away from the initial cancerous mass and, thus, evade surgical resection. Hence, therapies that target BTSCs and their invasive abilities may improve the otherwise poor prognosis of this disease. Our group and others have successfully established and characterized BTSC cultures from GBM patient samples. These BTSC cultures demonstrate fundamental cancer stem cell properties such as clonogenic self-renewal, multi-lineage differentiation, and tumor initiation in immune-deficient mice. In order to improve on the current therapeutic approaches for GBM, a better understanding of the mechanisms of BTSC migration and invasion is necessary. In GBM, the study of migration and invasion is restricted, in part, due to the limitations of existing techniques which do not fully account for the in vitro growth characteristics of BTSCs grown as neurospheres. Here, we describe rapid and quantitative live-cell imaging assays to study both the migration and invasion properties of BTSCs. The first method described is the BTSC migration assay which measures the migration toward a chemoattractant gradient. The second method described is the BTSC invasion assay which images and quantifies a cellular invasion from neurospheres into a matrix. The assays described here are used for the quantification of BTSC migration and invasion over time and under different treatment conditions.

Here, we describe live-cell imaging techniques to quantitatively measure the migration and invasion of glioblastoma brain tumor stem cells over time and under multiple treatment conditions.

Imagem latente da viver-pilha ensaios de migração de células-tronco do estudo Glioblastoma cerebral Tumor e invasão

Glioblastoma (GBM) is an aggressive brain tumor that is poorly controlled with the currently available treatment options. Key features of GBMs include ...

Pesquisa do câncer

Analysis of Trunk Neural Crest Cell Migration using a Modified Zigmond Chamber Assay

Neural crest cells (NCCs) are a transient population of cells present in vertebrate development that emigrate from the dorsal neural tube (NT) after undergoing an epithelial-mesenchymal transition 1,2. Following EMT, NCCs migrate large distances along stereotypic pathways until they reach their targets. NCCs differentiate into a vast array of cell types including neurons, glia, melanocytes, and chromaffin cells 1-3. The ability of NCCs to reach and recognize their proper target locations is foundational for the appropriate formation of all structures containing trunk NCC-derived components 3. Elucidating the mechanisms of guidance for trunk NCC migration has therefore been a matter of great significance. Numerous molecules have been demonstrated to guide NCC migration 4. For instance, trunk NCCs are known to be repelled by negative guidance cues such as Semaphorin, Ephrin, and Slit ligands 5-8. However, not until recently have any chemoattractants of trunk NCCs been identified 9. 
Conventional in vitro approaches to studying the chemotactic behavior of adherent cells work best with immortalized, homogenously distributed cells, but are more challenging to apply to certain primary stem cell cultures that initially lack a homogenous distribution and rapidly differentiate (such as NCCs). One approach to homogenize the distribution of trunk NCCs for chemotaxis studies is to isolate trunk NCCs from primary NT explant cultures, then lift and replate them to be almost 100% confluent. However, this plating approach requires substantial amounts of time and effort to explant enough cells, is harsh, and distributes trunk NCCs in a dissimilar manner to that found in in vivo conditions. 
Here, we report an in vitro approach that is able to evaluate chemotaxis and other migratory responses of trunk NCCs without requiring a homogenous cell distribution. This technique utilizes time-lapse imaging of primary, unperturbed trunk NCCs inside a modified Zigmond chamber (a standard Zigmond chamber is described elsewhere10). By exposing trunk NCCs at the periphery of the culture to a chemotactant gradient that is perpendicular to their predicted natural directionality, alterations in migratory polarity induced by the applied chemotactant gradient can be detected. This technique is inexpensive, requires the culturing of only two NT explants per replicate treatment, avoids harsh cell lifting (such as trypsinization), leaves trunk NCCs in a more similar distribution to in vivo conditions, cuts down the amount of time between explantation and experimentation (which likely reduces the risk of differentiation), and allows time-lapse evaluation of numerous migratory characteristics.

An approach to analyze the migration of explanted cells (trunk neural crest cells) is described. This method is inexpensive, gentle, and capable of distinguishing chemotaxis from both chemokinesis and other influences on migratory polarity such as those derived from cell-cell interactions within the primary trunk neural crest cell culture.

Análise de Tronco de Migração da crista neural celular usando uma modificação Zigmond Ensaio Câmara

Neural crest cells (NCCs) are a transient population of cells present in vertebrate development that emigrate from the dorsal neural tube (NT) after ...

Study of Cell Migration in Microfabricated Channels

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 impose a polarized phenotype to cells by physical constraints. Once inside channels, cells have only two possibilities: move forward or backward. This simplified migration in which directionality is restricted facilitates the automatic tracking of cells and the extraction of quantitative parameters to describe cell movement. These parameters include cell velocity, changes in direction, and pauses during motion. Microchannels are also compatible with the use of fluorescent markers and are therefore suitable to study localization of intracellular organelles and structures during cell migration at high resolution. Finally, the surface of the channels can be functionalized with different substrates, allowing the control of the adhesive properties of the channels or the study of haptotaxis. In summary, the system here described is intended to analyze the migration of large cell numbers in conditions in which both the geometry and the biochemical nature of the environment are controlled, facilitating the normalization and reproducibility of independent experiments.

A quantitative method to study spontaneous migration of cells in a one-dimensional confined microenvironment is described. This method takes advantage of microfabricated channels and can be used to study migration of large number of cells under different conditions in single experiments.

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 ...

A Galvanotaxis Assay for Analysis of Neural Precursor Cell Migration Kinetics in an Externally Applied Direct Current Electric Field

The discovery of neural stem and progenitor cells (collectively termed neural precursor cells) (NPCs) in the adult mammalian brain has led to a body of research aimed at utilizing the multipotent and proliferative properties of these cells for the development of neuroregenerative strategies. A critical step for the success of such strategies is the mobilization of NPCs toward a lesion site following exogenous transplantation or to enhance the response of the endogenous precursors that are found in the periventricular region of the CNS. Accordingly, it is essential to understand the mechanisms that promote, guide, and enhance NPC migration. Our work focuses on the utilization of direct current electric fields (dcEFs) to promote and direct NPC migration - a phenomenon known as galvanotaxis. Endogenous physiological electric fields function as critical cues for cell migration during normal development and wound repair. Pharmacological disruption of the trans-neural tube potential in axolotl embryos causes severe developmental malformations1. In the context of wound healing, the rate of repair of wounded cornea is directly correlated with the magnitude of the epithelial wound potential that arises after injury, as shown by pharmacological enhancement or disruption of this dcEF2-3. We have demonstrated that adult subependymal NPCs undergo rapid and directed cathodal migration in vitro when exposed to an externally applied dcEF. In this protocol we describe our lab's techniques for creating a simple and effective galvanotaxis assay for high-resolution, long-term observation of directed cell body translocation (migration) on a single-cell level. This assay would be suitable for investigating the mechanisms that regulate dcEF transduction into cellular motility through the use of transgenic or knockout mice, short interfering RNA, or specific receptor agonists/antagonists.

In this protocol we demonstrate how to construct custom chambers that permit the application of a direct current electric field to enable time-lapse imaging of adult brain derived neural precursor cell translocation during galvanotaxis.

Um Ensaio Galvanotaxis para Análise de Precursores Neurais Cinética migração celular em um campo aplicado externamente Corrente Contínua Elétrica

The discovery of neural stem and progenitor  cells (collectively termed neural precursor cells) (NPCs) in the adult  mammalian brain has led to a body of ...

Planar Gradient Diffusion System to Investigate Chemotaxis in a 3D Collagen Matrix

The importance of cell migration can be seen through the development of human life. When cells migrate, they generate forces and transfer these forces to their surrounding area, leading to cell movement and migration. In order to understand the mechanisms that can alter and/or affect cell migration, one can study these forces. In theory, understanding the fundamental mechanisms and forces underlying cell migration holds the promise of effective approaches for treating diseases and promoting cellular transplantation. Unfortunately, modern chemotaxis chambers that have been developed are usually restricted to two dimensions (2D) and have complex diffusion gradients that make the experiment difficult to interpret. To this end, we have developed, and describe in this paper, a direct-viewing chamber for chemotaxis studies, which allows one to overcome modern chemotaxis chamber obstacles able to measure cell forces and specific concentration within the chamber in a 3D environment to study cell 3D migration. More compelling, this approach allows one to successfully model diffusion through 3D collagen matrices and calculate the coefficient of diffusion of a chemoattractant through multiple different concentrations of collagen, while keeping the system simple and user friendly for traction force microscopy (TFM) and digital volume correlation (DVC) analysis.

Cell migration is an important part of human development and life. In order to understand the mechanisms that can alter cell migration, we present a planar gradient diffusion system to investigate chemotaxis in a 3D collagen matrix, which allows one to overcome modern diffusion chamber limitations of existing assays.

Gradiente planar do sistema de difusão para investigar Quimiotaxia numa Matriz de Colagénio 3D

The importance of cell migration can be seen through the development of human life. When cells migrate, they generate forces and transfer these forces to ...

Measurement of Cellular Chemotaxis with ECIS/Taxis

Cellular movement in response to external stimuli is fundamental to many cellular processes including wound healing, inflammation and the response to infection. A common method to measure chemotaxis is the Boyden chamber assay, in which cells and chemoattractant are separated by a porous membrane. As cells migrate through the membrane toward the chemoattractant, they adhere to the underside of the membrane, or fall into the underlying media, and are subsequently stained and visually counted 1. In this method, cells are exposed to a steep and transient chemoattractant gradient, which is thought to be a poor representation of gradients found in tissues 2.
Another assay system, the under-agarose chemotaxis assay, 3, 4 measures cell movement across a solid substrate in a thin aqueous film that forms under the agarose layer. The gradient that develops in the agarose is shallow and is thought to be an appropriate representation of naturally occurring gradients. Chemotaxis can be evaluated by microscopic imaging of the distance traveled. Both the Boyden chamber assay and the under-agarose assay are usually configured as endpoint assays.
The automated ECIS/Taxis system combines the under-agarose approach with Electric Cell-substrate Impedance Sensing (ECIS) 5, 6. In this assay, target electrodes are located in each of 8 chambers. A large counter-electrode runs through each of the 8 chambers (Figure 2). Each chamber is filled with agarose and two small wells are the cut in the agarose on either side of the target electrode. One well is filled with the test cell population, while the other holds the sources of diffusing chemoattractant (Figure 3). Current passed through the system can be used to determine the change in resistance that occurs as cells pass over the target electrode. Cells on the target electrode increase the resistance of the system 6. In addition, rapid fluctuations in the resistance represent changes in the interactions of cells with the electrode surface and are indicative of ongoing cellular shape changes. The ECIS/Taxis system can measure movement of the cell population in real-time over extended periods of time, but is also sensitive enough to detect the arrival of a single cell at the target electrode. 
Dictyostelium discoidium is known to migrate in the presence of a folate gradient 7, 8 and its chemotactic response can be accurately measured by ECIS/Taxis 9. Leukocyte chemotaxis, in response to SDF1&alpha; and to chemotaxis antagonists has also been measured with ECIS/Taxis 10, 11. An example of the leukocyte response to SDF1&alpha; is shown in Figure 1.

The ECIS/Taxis system is an automated, real-time assay that measures cellular chemotaxis. In this assay, cells move beneath a layer of agarose to arrive at a target electrode. Cellular movement is measured by the onset of resistance to AC current 0.

Medição de Quimiotaxia celulares com ECIS / Taxis

Cellular movement in response to external stimuli is fundamental to many cellular processes including wound healing, inflammation and the response to ...

Biologia

Imaging G Protein-coupled Receptor-mediated Chemotaxis and its Signaling Events in Neutrophil-like HL60 Cells

Eukaryotic cells sense and move towards a chemoattractant gradient, a cellular process referred as chemotaxis. Chemotaxis plays critical roles in many physiological processes, such as embryogenesis, neuron patterning, metastasis of cancer cells, recruitment of neutrophils to sites of inflammation, and the development of the model organism Dictyostelium discoideum. Eukaryotic cells sense chemo-attractants using G protein-coupled receptors. Visual chemotaxis assays are essential for a better understanding of how eukaryotic cells control chemoattractant-mediated directional cell migration. Here, we describe detailed methods for: 1) real-time, high-resolution monitoring of multiple chemotaxis assays, and 2) simultaneously visualizing the chemoattractant gradient and the spatiotemporal dynamics of signaling events in neutrophil-like HL60 cells.

Visual chemotaxis assays are essential for a better understanding of how eukaryotic cells control chemoattractant-mediated directional cell migration. Here, we describe detailed methods for: 1) real-time, high-resolution monitoring of multiple chemotaxis assays, and 2) simultaneously visualizing the chemoattractant gradient and the spatiotemporal dynamics of signaling events in neutrophil-like HL60 cells.

Imagiologia G protein-coupled receptor mediada por quimiotaxia e seus eventos de sinalização em células de HL60 de Neutrófilos-like

Eukaryotic cells sense and move towards a chemoattractant gradient, a cellular process referred as chemotaxis. Chemotaxis plays critical roles in many ...