Los autores reconocen el uso del laboratorio de análisis de la superficie en la Universidad Johns Hopkins, financiado en el marco de la Investigación en Ciencias de Materiales e Ingeniería a través de la National Science Foundation. LED es un aprendiz de IGERT y un becario de la Fundación Nacional de Ciencias de Posgrado. Esta investigación fue financiada parcialmente por el NIH subvención U54CA143868.

1. La fotolitografía estándar para la fabricación de sellos micropatterned <ol><li> Aclarar una oblea de silicio nuevo con etanol y secar con corriente de aire. Use unas pinzas para manipular la oblea y prevenir los defectos de la superficie durante todo el proceso. </li><li> Transferencia de obleas para hacer girar recubrimiento y cubrir la superficie de la oblea con el SU-2025 fotosensible negativa. Cubrir al menos el 80% de la oblea con fotoprotector. Giro capa durante 10 segundos a 600 rpm, seguido de 30 segundos a 3000 rpm. Debido a la fotosensibilidad de la fotosensible, apagar luces de la sala a partir de ahora. </li><li> Transferencia de obleas de silicio fotosensible recubierto con placa caliente de &quot;soft-cocer al horno&quot; a 95 ° C durante 3 minutos. Retire de la placa caliente y dejar un minuto para enfriar. </li><li> Coloque una pre-fabricados máscara con el modelo deseado en la parte superior de la oblea de silicio fotosensible cubierto y exponer a los rayos ultravioleta (UV) (350-450 nm) durante 20 segundos. </li><li> Transferencia de obleas de silicio de la placa caliente de &quot;hard-cocer al horno&quot; a 110 ° C durante 6 minutos. </li><li> Encienda las luces y retirar la oblea de la placa caliente. Distintos patrones deben ser visibles en este momento. </li><li> Enjuagar cuidadosamente oblea de silicio con SU-8 desarrollador fotosensible. Después de tres enjuagues con solución reveladora, enjuagar con etanol. Si cualquier residuo blanco, repita enjuague con solución reveladora fotosensible, o simplemente sumergirse en la oblea solución reveladora durante 2 minutos y proceder de nuevo con etanol enjuague. Lavar con agua y aire seco. </li><li> Mezcla de polidimetilsiloxano (PDMS) solución de elastómero y agente de curado en una proporción de 10:1. Centrifugar a 900 rpm durante 5 minutos para eliminar las burbujas de aire. </li><li> Lugar con dibujos de obleas en una placa de Petri y verter PDMS en oblea de silicio. Si hay burbujas presentes, lugar en desecador de vacío y un par de minutos hasta que las burbujas desaparezcan. </li><li> Curar toda la noche a temperatura ambiente (TA) para formar un sello elastomérico complementarias. Si PDMS no sana completamente después de 12 horas, lugar en el horno a 60 ° C durante 30 minutos. </li><li> Retire con cuidado PDMS de oblea de silicio. Use un filo de la navaja para cortar el sello al tamaño deseado. Sonicado en etanol durante 15 minutos. Obleas se pueden utilizar varias veces para crear nuevos sellos de elastómero. </li></ol> 2. HA micropatterning <ol><li> Plasma de vidrio limpio se desliza por 5 minutos. Coloque todos los portaobjetos en la cámara de vacío y durante 5 minutos. A continuación, permitir el flujo bajo de oxígeno para entrar en la cámara. A su vez limpio el plasma durante 5 minutos. Eliminar de limpiador de plasma y colocarlo en una placa de Petri con las pinzas. </li><li> Durante la limpieza de plasma, ultrasonidos sellos PDMS en etanol durante 15 minutos. </li><li> Preparar un nuevo máximo de 3% v / v de 3-aminopropiltrimetoxisilano (APTMS) en el 95% v / v de etanol en un tubo de centrífuga de 15 ml. Dejar actuar durante 5 minutos a temperatura ambiente para formar un silanol. </li><li> Coloque el sello del patrón de PDMS-up sobre la transferencia de aplicador plato y cubrir con una solución de modelado de superficie APTMS. Spincoat a 3500 rpm durante 30 segundos. No toque la superficie del sello, sólo los lados del sello PDMS. </li><li> Transferir la solución a la APTMS plasma limpiar las superficies de vidrio: El sello de conjunto hacia abajo en un extremo del lado del patrón y se deslizan suavemente presionando PDMS lo que es completamente en contacto con la superficie del vidrio durante 1 minuto. </li><li> Retire con cuidado el sello PDMS, y permitir que la diapositiva patrón de vidrio para la incubación en RT durante 30 minutos. Enjuague las superficies modeladas con etanol y secar al aire. Sonicar PDMS sello durante 15 minutos para eliminar el exceso de APTMS. </li><li> Las superficies de calor en el horno o en la placa caliente durante 1 hora a 115 º C. Enjuagar con etanol y secar con aire. </li><li> Prepare polietilenglicol fresca (PEG)-silano solución de 20% v / v 2 - [metoxi (polietilenoxi) propil] trimetoxisilano en tolueno. Esto servirá como una región no adhesiva alrededor de los patrones. </li><li> Transferencia de lámina de vidrio con dibujos a un plato de Petri de vidrio y se incuban en PEG-silano solución durante 45 minutos a 75 ° C en un plato caliente. Enjuague con tolueno, el agua y secar con aire. </li><li> Esterilizar durante 1 hora con irradiación germicida ultravioleta en una cámara de seguridad biológica. Proceder en el gabinete de seguridad biológica a partir de ahora para mantener la esterilidad. </li><li> Prepare una solución acuosa estéril HA. 10 mM de 1-etil-3-(3-dimetilaminopropil) carbodiimida (EDC) 5 mM de N-hidroxisuccinimida 50 microgramos / ml marcado con fluoresceína HA </li><li> Aplique una solución de HA a los sustratos de vidrio con dibujos en condiciones de esterilidad y protegido de la luz. Estampados sustratos deben ser molestados durante 16-24 horas. </li><li> Aspirar de solución de HA, lavar con tampón fosfato salino (PBS), y cubrir la superficie con bovino al 1% de albúmina sérica (BSA) en PBS durante 1 hora. La superficie ya está lista para el cultivo celular. </li></ol> 3. Cultivo de células en superficies HA micropatterned <ol><li> Ampliar MDA-MB-231 células humanas de cáncer de mama y LS174T células carcinoma colorrectal, de acuerdo con las instrucciones del fabricante. </li><li> Suspensiones de semillas de células individuales de las células cancerosas con una densidad de entre 0,4 y 1x10 <sup&gt; 6 células cancerosas por 18,75 cm 2 de superficie de vidrio y en superficies HA inmovilizado. Incubar en incubadora humidificada (37 ° C) en atmósferas mantiene con 5% de CO 2. La adhesión celular debe ocurrir dentro de 24 horas y se puede observar con microscopio de luz invertida </li><li> Las superficies de cultivo celular puede mantenerse hasta por 5 días en condiciones estándar de la incubadora. Cambiar los medios de comunicación todos los días. Morfología de las células y el crecimiento se puede observar con microscopio de luz invertida. Otros ensayos celulares se pueden aplicar para analizar las respuestas a la superficie de HA. </li></ol> 4. Los resultados representativos: La química carbodiimida para inmovilizar covalentemente HA a las diapositivas de cristal APTMS patrón se muestra en la Figura 1. EDC es un agente de reticulación de longitud cero que reacciona con grupos carboxilo HA para formar amina reactiva intermedios. Ya que este medio es susceptible a la hidrólisis, NHS se agrega para aumentar la eficacia de la reacción de carbodiimida. Como solución de HA interactúa con micropatrones APTMS, se forma una amida estable vínculo entre HA intermedios y amina primaria de ATPMS. Un ejemplo de HA superficie modelada visualizaron utilizando un microscopio de fluorescencia y un análisis ImageJ intensidad de fluorescencia demostrar la inmovilización con dibujos de HA se muestran (Figura 1B-C). Las superficies HA micropatterned permitirá el estudio de las interacciones de célula de cáncer con HA expgenous. Tanto MDA-MB-231 materna y LS174T líneas celulares humanas de cáncer de colon preferentemente se adhieren a las regiones micropatterned HA (Figura 2). Imágenes de alta resolución mediante microscopía electrónica de barrido se puede utilizar para analizar las interacciones de las células cultivadas con superficies HA inmovilizado (Figura 3). <img src="/files/ftp_upload/2413/2413fig1.jpg" alt="Figura 1" /> Figura 1 HA micropatterned superficies (A) Esquema que describe el desarrollo de superficies funcionales HA, (B) Imagen de fluorescencia de la fluoresceína (verde) de la etiqueta HA superficie micropatterned. (C) de píxeles 3D mapa de distribución utilizando el software ImageJ demostrando los patrones HA discretos. Barra de escala = 100μm. Modificado a partir de 9 con permiso de Elsevier. <img src="/files/ftp_upload/2413/2413fig2.jpg" alt="Figura 2" /> Figura 2. Cáncer de adhesión celular en las superficies HA micropatterned. Ambos puntos (A) y de mama (B) carcinoma de preferencia conforme a los parches de HA con 24 horas de cultivo. Modificado a partir de 9 con permiso de Elsevier. <img src="/files/ftp_upload/2413/2413fig3.jpg" alt="Figura 3" /> Figura 3. Interacción de las células del cáncer con HA. (A) Digitalización de imágenes de microscopía electrónica de las células de cáncer de colon (A) en las superficies cultivadas HA demostrado a bajo aumento (izquierda) y el gran aumento (derecha, de las plazas a la izquierda) y de las células de cáncer de mama (B) cultivadas en las superficies de HA se muestra a bajo aumento (izquierda) y el gran aumento (derecha, de los cuadrados de la izquierda).

<ol>
	<li>Toole, B. P., Wight, T. N., Tammi, M. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hyaluronan-cell+interactions+in+cancer+and+vascular+disease.">Hyaluronan-cell interactions in cancer and vascular disease.</a> Journal of Biological Chemistry. 277, 4593-4596 (2002).</li><li>Hamilton, S. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Hyaluronan+Receptors+CD44+and+Rhamm+(CD168)+Form+Complexes+with+ERK1,2+That+Sustain+High+Basal+Motility+in+Breast+Cancer+Cells.">The Hyaluronan Receptors CD44 and Rhamm (CD168) Form Complexes with ERK1,2 That Sustain High Basal Motility in Breast Cancer Cells.</a> Journal of Biological Chemistry. 282, 16667-16680 (2007).</li><li>G&#246;tte, M., Yip, G. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heparanase,+Hyaluronan,+and+CD44+in+Cancers:+A+Breast+Carcinoma+Perspective.">Heparanase, Hyaluronan, and CD44 in Cancers: A Breast Carcinoma Perspective.</a> Cancer Research. 66, 10233-10237 (2006).</li><li>Lord, M. S., Pasqui, D., Barbucci, R., Milthorpe, B. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Protein+adsorption+on+derivatives+of+hyaluronic+acid+and+subsequent+cellular+response.">Protein adsorption on derivatives of hyaluronic acid and subsequent cellular response.</a> Journal of Biomedical Materials Research. Part A 91, 635-646 (2009).</li><li>Barbucci, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modification+of+hyaluronic+acid+by+sulphate+groups+insertion+to+obtain+a+heparin-like+molecule.">Modification of hyaluronic acid by sulphate groups insertion to obtain a heparin-like molecule.</a> Gazz. Chim. Ital. 125, 169-180 (1995).</li><li>Morra, M., Cassinelli, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Non-fouling+properties+of+polysaccharide-coated+surfaces.">Non-fouling properties of polysaccharide-coated surfaces.</a> Journal of Biomaterials Science, Polymer Edition. 10, 1107-1124 (1999).</li><li>Khademhosseini, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Layer-by-layer+deposition+of+hyaluronic+acid+and+poly-L-lysine+for+patterned+cell+co-cultures.">Layer-by-layer deposition of hyaluronic acid and poly-L-lysine for patterned cell co-cultures.</a> Biomaterials. 25, 3583-3592 (2004).</li><li>Ibrahim, S., Joddar, B., Craps, M., Ramamurthi, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+surface-tethered+model+to+assess+size-specific+effects+of+hyaluronan+(HA)+on+endothelial+cells.">A surface-tethered model to assess size-specific effects of hyaluronan (HA) on endothelial cells.</a> Biomaterials. 28, 825-835 (2007).</li><li>Dickinson, L. E., Ho, C. C., Wang, G. M., Stebe, K. J., Gerecht, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+surfaces+for+high-resolution+analysis+of+cancer+cell+interactions+on+exogenous+hyaluronic+acid.">Functional surfaces for high-resolution analysis of cancer cell interactions on exogenous hyaluronic acid.</a> Biomaterials. 31, 5472-5478 (2010).</li><li>Gao, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hyaluronan+oligosaccharides+promote+excisional+wound+healing+through+enhanced+angiogenesis.">Hyaluronan oligosaccharides promote excisional wound healing through enhanced angiogenesis.</a> Matrix Biology. 29, 107-116 (2010).</li><li>Slevin, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hyaluronan-mediated+angiogenesis+in+vascular+disease:+Uncovering+RHAMM+and+CD44+receptor+signaling+pathways.">Hyaluronan-mediated angiogenesis in vascular disease: Uncovering RHAMM and CD44 receptor signaling pathways.</a> Matrix Biology. 26, 58-68 (2007).</li></ol>

Figura esquemática de vídeo reproducido con permiso; Derechos de Autor Wiley-VCH Verlag GmbH &amp; Co. KGaA. Dickinson LE, Kusuma S, Gerecht S. La reconstrucción del nicho de diferenciación de las células madre embrionarias con biomateriales. Macromol. Biosci. 2010, 21 de octubre. [Epub ahead of print].

El método presentado micropatterning HA permite el estudio de las interacciones celulares con exógenos HA. HA se sabe que juega un papel clave en la progresión del cáncer 1, sin embargo ha habido pocos estudios investigando la interacción de las células cancerosas en dos dimensiones superficies HA patrón. Un estudio controlables en exógenos micropatrones HA de alta resolución permite la visualización de la adhesión de las células cancerosas, el crecimiento y la migración y puede aclarar aún más...

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		<th>Material Name</th>
		<th>Type</th>
		<th>Company</th>
		<th>Catalogue Number</th>
		<th>Comment</th>
		</tr>
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<tr>
<td>SU-2025 photoresist</td>
<td>&nbsp;</td>
<td>MicroChem Corp.</td>
<td>Y111069</td>
<td>&nbsp;</td>
<tr>
<td>SU-8 developer</td>
<td>&nbsp;</td>
<td>MicroChem Corp.</td>
<td>Y020100</td>
<td>&nbsp;</td>
<tr>
<td>Sylgard 184</td>
<td>&nbsp;</td>
<td>Dow Corning</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>3-aminopropyltrimethoxysilane (APTMS)</td>
<td>&nbsp;</td>
<td>Sigma-Aldrich</td>
<td>281778</td>
<td>&nbsp;</td>
<tr>
<td>2- [methoxy(polyethyleneoxy) propyl] trimethoxysilane (Peg-silane)</td>
<td>&nbsp;</td>
<td>Gelest Inc</td>
<td>SIM6492.7</td>
<td>&nbsp;</td>
<tr>
<td>1-Ethyl-3- (3-dimethylaminopropyl) carbodiimide</td>
<td>&nbsp;</td>
<td>Thermo Scientific</td>
<td>22980</td>
<td>&nbsp;</td>
<tr>
<td>N-hydroxysuccinimide (NHS)</td>
<td>&nbsp;</td>
<td>Thermo Scientific</td>
<td>24500</td>
<td>&nbsp;</td>
<tr>
<td>Fluorescein labeled hyaluronic acid (FL-HA)</td>
<td>&nbsp;</td>
<td>Sigma-Aldrick</td>
<td>F1177</td>
<td>Reconstitute with 10ml of DI water </td>
</tr>
<tr>
<td>MDA-MB-231 breast carcinoma cells</td>
<td>&nbsp;</td>
<td>ATCC</td>
<td>HTB-26</td>
<td>&nbsp;</td>
<tr>
<td>LS174t colon carcinoma cells</td>
<td>&nbsp;</td>
<td>ATCC</td>
<td>Cl-188</td>
<td>&nbsp;</td>		</tbody>
		</table>
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micropatterned surfaces to study hyaluronic acid interactions with cancer cells

Invasión y progresión del cáncer consiste en un fenotipo de células móviles, que se encuentra bajo una regulación compleja de factores de crecimiento / citocinas y componentes de la matriz extracelular (ECM) en el microambiente del tumor. El ácido hialurónico (HA) es un componente del estroma ECM que se conoce para facilitar la progresión del tumor por la invasión de la mejora, el crecimiento y la angiogénesis 1. Interacción de HA con su superficie celular CD44 receptor induce eventos de señalización que promueven el crecimiento celular del tumor, la supervivencia y la migración, aumentando así la diseminación metastásica 2-3. HA es un glicosaminoglicano aniónicos, nonsulfated compuesto por unidades repetidas de ácido D-glucurónico y DN-acetilglucosamina. Debido a la presencia de grupos carboxilo e hidroxilo en las unidades de disacárido repetir, HA nativo es en gran parte hidrofílica y es susceptible de modificaciones químicas que introducen grupos sulfato para la inmovilización de photoreative 4-5. Los estudios anteriores referentes a la inmovilización de HA en las superficies de utilizar el comportamiento bioresistant de HA y sus derivados sulfatados para controlar la adhesión celular en las superficies de 6-7. En estos estudios de forma preferente la adhesión celular se produce en las regiones no-HA patrón. Para el análisis de las interacciones celulares con HA exógeno, se han desarrollado patrones superficies funcionales que permiten un estudio controlable y de alta resolución de visualización de las interacciones de célula de cáncer con HA. Hemos utilizado la impresión microcontacto (UCP) para definir regiones discretas patrón de HA en la superficie de vidrio. A &quot;tethering&quot; enfoque que se aplica la química que une carbodiimida para inmovilizar HA fue utilizada 8. Las superficies de cristal se microcontacto impresa con una aminosilano y reaccionó con una solución de HA de las relaciones optimizada de la EDC y NHS para permitir la inmovilización en matrices de estampado HA. La incorporación de la química carbodiimida con MCP permitió la inmovilización de HA de regiones definidas, la creación de superficies aptas para aplicaciones in vitro. Tanto las células de cáncer de colon y las células de cáncer de mama implícitamente interactuado con la superficie de HA micropatterned. Adhesión de las células cancerosas se produjo dentro de las 24 horas, con la proliferación de las 48 horas. HA utilizando superficies micropatterned, hemos demostrado que la adherencia de las células cancerosas se produce a través del receptor CD44 HA. Por otra parte, HA superficies modeladas eran compatibles con microscopía electrónica de barrido (SEM) y de imágenes permitió a alta resolución de las protuberancias del cáncer de células adhesivo y la difusión en los patrones de HA para analizar la motilidad de las células cancerosas en HA exógeno.

Watch this Scientific Journal Video about Micropatterned Surfaces to Study Hyaluronic Acid Interactions with Cancer Cells at JoVE.com

Micropatterned Surfaces to Study Hyaluronic Acid Interactions with Cancer Cells

Un nuevo enfoque que permite el análisis de la alta resolución de las interacciones de célula de cáncer con exógena de ácido hialurónico (HA) se describe. Superficies modeladas se fabrican mediante la combinación de la química y la impresión por microcontacto carbodiimida.

Superficies micropatterned para estudiar las interacciones de ácido hialurónico con células de cáncer

Cancer invasion and progression involves a motile cell phenotype, which is under complex regulation by growth factors/cytokines and extracellular matrix ...

micropatterned-surfaces-to-study-hyaluronic-acid-interactions-with

Research

JoVE Journal

Bioengineering

15.0K vistas.  Johns Hopkins University. Un nuevo enfoque que permite el análisis de la alta resolución de las interacciones de célula de cáncer con exógena de ácido hialurónico (HA) se describe. Superficies modeladas se fabrican mediante la combinación de la química y la impresión por microcontacto carbodiimida.

Video: Micropatterned Surfaces to Study Hyaluronic Acid Interactions with Cancer Cells

Improved Visualization and Quantitative Analysis of Drug Effects Using Micropatterned Cells

To date, most HCA (High Content Analysis) studies are carried out with adherent cell lines grown on a homogenous substrate in tissue-culture treated micro-plates. Under these conditions, cells spread and divide in all directions resulting in an inherent variability in cell shape, morphology and behavior. The high cell-to-cell variance of the overall population impedes the success of HCA, especially for drug development. The ability of micropatterns to normalize the shape and internal polarity of every individual cell provides a tremendous opportunity for solving this critical bottleneck 1-2.
To facilitate access and use of the micropatterning technology, CYTOO has developed a range of ready to use micropatterns, available in coverslip and microwell formats. In this video article, we provide detailed protocols of all the procedures from cell seeding on CYTOOchip micropatterns, drug treatment, fixation and staining to automated acquisition, automated image processing and final data analysis. With this example, we illustrate how micropatterns can facilitate cell-based assays. Alterations of the cell cytoskeleton are difficult to quantify in cells cultured on homogenous substrates, but culturing cells on micropatterns results in a reproducible organization of the actin meshwork due to systematic positioning of the cell adhesion contacts in every cell. Such normalization of the intracellular architecture allows quantification of even small effects on the actin cytoskeleton as demonstrated in these set of protocols using blebbistatin, an inhibitor of the actin-myosin interaction.

Adhesive micropatterns that normalize cellular architecture can be used to increase sensitivity in the detection of drug effects, improve reproducibility and simplify automated image acquisition and analysis. Such technology will benefit drug/siRNA screening assays, performed on conventional cell culture supports and consequently suffering from excessive cell-to-cell variability.

Una mejor visualización y análisis cuantitativo de los efectos de drogas Uso de células micropatterned

To date, most HCA (High Content Analysis) studies are carried out with adherent cell lines grown on a homogenous substrate in tissue-culture treated ...

Investigación

Bioingeniería

Design of a Cyclic Pressure Bioreactor for the Ex Vivo Study of Aortic Heart Valves

The aortic valve, located between the left ventricle and the aorta, allows for unidirectional blood flow, preventing backflow into the ventricle. Aortic valve leaflets are composed of interstitial cells suspended within an extracellular matrix (ECM) and are lined with an endothelial cell monolayer. The valve withstands a harsh, dynamic environment and is constantly exposed to shear, flexion, tension, and compression. Research has shown calcific lesions in diseased valves occur in areas of high mechanical stress as a result of endothelial disruption or interstitial matrix damage1-3. Hence, it is not surprising that epidemiological studies have shown high blood pressure to be a leading risk factor in the onset of aortic valve disease4. 
The only treatment option currently available for valve disease is surgical replacement of the diseased valve with a bioprosthetic or mechanical valve5. Improved understanding of valve biology in response to physical stresses would help elucidate the mechanisms of valve pathogenesis. In turn, this could help in the development of non-invasive therapies such as pharmaceutical intervention or prevention. Several bioreactors have been previously developed to study the mechanobiology of native or engineered heart valves6-9. Pulsatile bioreactors have also been developed to study a range of tissues including cartilage10, bone11 and bladder12. The aim of this work was to develop a cyclic pressure system that could be used to elucidate the biological response of aortic valve leaflets to increased pressure loads. 
The system consisted of an acrylic chamber in which to place samples and produce cyclic pressure, viton diaphragm solenoid valves to control the timing of the pressure cycle, and a computer to control electrical devices. The pressure was monitored using a pressure transducer, and the signal was conditioned using a load cell conditioner. A LabVIEW program regulated the pressure using an analog device to pump compressed air into the system at the appropriate rate. The system mimicked the dynamic transvalvular pressure levels associated with the aortic valve; a saw tooth wave produced a gradual increase in pressure, typical of the transvalvular pressure gradient that is present across the valve during diastole, followed by a sharp pressure drop depicting valve opening in systole. The LabVIEW program allowed users to control the magnitude and frequency of cyclic pressure. The system was able to subject tissue samples to physiological and pathological pressure conditions. This device can be used to increase our understanding of how heart valves respond to changes in the local mechanical environment.

Design of a Cyclic Pressure Bioreactor for the Ex Vivo Study of Aortic Heart Valves

A cyclic pressure bioreactor capable of subjecting heart valve tissue to physiological and pathological pressure conditions has been designed. A LabVIEW program allows users to control pressure magnitude, amplitude and frequency. This device can be used to study the mechanobiology of heart valve tissue or isolated cells.

Diseño de un biorreactor de presión cíclica de la Ex Vivo Estudio de las válvulas aórtica del corazón

The aortic valve, located between the left ventricle and the aorta, allows for unidirectional blood flow, preventing backflow into the ventricle. Aortic ...

Endothelialized Microfluidics for Studying Microvascular Interactions in Hematologic Diseases

Advances in microfabrication techniques have enabled the production of inexpensive and reproducible microfluidic systems for conducting biological and biochemical experiments at the micro- and nanoscales 1,2. In addition, microfluidics have also been specifically used to quantitatively analyze hematologic and microvascular processes, because of their ability to easily control the dynamic fluidic environment and biological conditions3-6. As such, researchers have more recently used microfluidic systems to study blood cell deformability, blood cell aggregation, microvascular blood flow, and blood cell-endothelial cell interactions6-13.However, these microfluidic systems either did not include cultured endothelial cells or were larger than the sizescale relevant to microvascular pathologic processes. A microfluidic platform with cultured endothelial cells that accurately recapitulates the cellular, physical, and hemodynamic environment of the microcirculation is needed to further our understanding of the underlying biophysical pathophysiology of hematologic diseases that involve the microvasculature.
Here, we report a method to create an "endothelialized" in vitro model of the microvasculature, using a simple, single mask microfabrication process in conjunction with standard endothelial cell culture techniques, to study pathologic biophysical microvascular interactions that occur in hematologic disease. This "microvasculature-on-a-chip" provides the researcher with a robust assay that tightly controls biological as well as biophysical conditions and is operated using a standard syringe pump and brightfield/fluorescence microscopy. Parameters such as microcirculatory hemodynamic conditions, endothelial cell type, blood cell type(s) and concentration(s), drug/inhibitory concentration etc., can all be easily controlled. As such, our microsystem provides a method to quantitatively investigate disease processes in which microvascular flow is impaired due to alterations in cell adhesion, aggregation, and deformability, a capability unavailable with existing assays.

A method to culture an endothelial cell monolayer throughout the entire inner 3D surface of a microfluidic device with microvascular-sized channels (&lt;30 &mu;m) is described. This in vitro microvasculature model enables the study of biophysical interactions between blood cells, endothelial cells, and soluble factors in hematologic diseases.

Microfluídica endotelizado para estudiar las interacciones microvasculares en Enfermedades Hematológicas

Advances in  microfabrication techniques have enabled the production of inexpensive and  reproducible microfluidic systems for conducting biological and ...

Stretching Micropatterned Cells on a PDMS Membrane

Mechanical forces exerted on cells and/or tissues play a major role in numerous processes. We have developed a device to stretch cells plated on a PolyDiMethylSiloxane (PDMS) membrane, compatible with imaging. This technique is reproducible and versatile. The PDMS membrane can be micropatterned in order to confine cells or tissues to a specific geometry. The first step is to print micropatterns onto the PDMS membrane with a deep UV technique. The PDMS membrane is then mounted on a mechanical stretcher. A chamber is bound on top of the membrane with biocompatible grease to allow gliding during the stretch. The cells are seeded and allowed to spread for several hours on the micropatterns. The sample can be stretched and unstretched multiple times with the use of a micrometric screw. It takes less than a minute to apply the stretch to its full extent (around 30%). The technique presented here does not include a motorized device, which is necessary for applying repeated stretch cycles quickly and/or computer controlled stretching, but this can be implemented. Stretching of cells or tissue can be of interest for questions related to cell forces, cell response to mechanical stress or tissue morphogenesis. This video presentation will show how to avoid typical problems that might arise when doing this type of seemingly simple experiment.

This manuscript presents a technique to apply or release forces on adherent cells or tissues using unidirectional stretching.

El estiramiento células micropatterned en una membrana de PDMS

Mechanical forces exerted on cells and/or tissues  play a major role in numerous processes. We have developed a device to stretch  cells plated on a ...

Tissue Engineering of Tumor Stromal Microenvironment with Application to Cancer Cell Invasion

3D organotypic cultures of epithelial cells on a matrix embedded with mesenchymal cells are widely used to study epithelial cell differentiation and invasion. Rat tail type I collagen and/or matrix derived from Engelbreth-Holm-Swarm mouse sarcoma cells have been traditionally employed as the substrates to model the matrix or stromal microenvironment into which mesenchymal cells (usually fibroblasts) are populated. Although experiments using such matrices are very informative, it can be argued that due to an overriding presence of a single protein (such as in type I Collagen) or a high content of basement membrane components and growth factors (such as in matrix derived from mouse sarcoma cells), these substrates do not best reflect the contribution to matrix composition made by the stromal cells themselves. To study native matrices produced by primary dermal fibroblasts isolated from patients with a tumor prone, genetic blistering disorder (recessive dystrophic epidermolysis bullosa), we have adapted an existing native matrix protocol to study tumor cell invasion. Fibroblasts are induced to produce their own matrix over a prolonged period in culture. This native matrix is then detached from the culture dish and epithelial cells are seeded onto it before the entire coculture is raised to the air-liquid interface. Cellular differentiation and/or invasion can then be assessed over time. This technique provides the ability to assess epithelial-mesenchymal cell interactions in a 3D setting without the need for a synthetic or foreign matrix with the only disadvantage being the prolonged period of time required to produce the native matrix. Here we describe the application of this technique to assess the ability of a single molecule expressed by fibroblasts, type VII collagen, to inhibit tumor cell invasion.

Tissue engineered fibroblast-derived native matrix is an emerging tool to generate a stromal substrate which supports epithelial cell proliferation and differentiation. Here a protocol applying this methodology to assess the impact of different stromal cell types on tumor cell biology is presented.

Ingeniería de tejidos de tumor del estroma Microambiente con Aplicación a la invasión de células cancerosas

3D organotypic cultures of epithelial cells on a matrix embedded with mesenchymal cells are widely used to study epithelial cell differentiation and ...

Gene Transfection toward Spheroid Cells on Micropatterned Culture Plates for Genetically-modified Cell Transplantation

To improve the therapeutic effectiveness of cell transplantation, a transplantation system of genetically modified, injectable spheroids was developed. The cell spheroids are prepared in a culture system on micropatterned plates coated with a thermosensitive polymer. A number of spheroids are formed on the plates, corresponding to the cell adhesion areas of 100 &#181;m diameter that are regularly arrayed in a two-dimensional manner, surrounded by non-adhesive areas that are coated by a polyethylene glycol (PEG) matrix. The spheroids can be easily recovered as a liquid suspension by lowering the temperature of the plates, and their structure is well maintained by passing them through injection needles with a sufficiently large caliber (over 27 G). Genetic modification is achieved by gene transfection using the original non-viral gene carrier, polyplex nanomicelle, which is capable of introducing genes into cells without disrupting the spheroid structure. For primary hepatocyte spheroids transfected with a luciferase-expressing gene, the luciferase is sustainably obtained in transplanted animals, along with preserved hepatocyte function, as indicated by albumin expression. This system can be applied to a variety of cell types including mesenchymal stem cells.

This protocol describes a cell transplantation system using genetically modified, injectable spheroids. Cell spheroids are cultured on micropatterned culture plates and recovered after gene introduction using polyplex nanomicelles. This system facilitates prolonged transgene expression from the transplanted cells in host animals while maintaining the innate function of the cells.

La transfección de genes hacia células Esferoide sobre placas micropatterned Cultura para el trasplante de células genéticamente modificadas

To improve the therapeutic effectiveness of cell transplantation, a transplantation system of genetically modified, injectable spheroids was developed. ...

Preparation of Thermoresponsive Nanostructured Surfaces for Tissue Engineering

Thermoresponsive poly(N-isopropylacrylamide) (PIPAAm)-immobilized surfaces for controlling cell adhesion and detachment were fabricated by the Langmuir-Schaefer method. Amphiphilic block copolymers composed of polystyrene and PIPAAm (St-IPAAms) were synthesized by reversible addition-fragmentation chain transfer (RAFT) radical polymerization. A chloroform solution of St-IPAAm molecules was gently dropped into a Langmuir-trough apparatus, and both barriers of the apparatus were moved horizontally to compress the film to regulate its density. Then, the St-IPAAm Langmuir film was horizontally transferred onto a hydrophobically modified glass substrate by a surface-fixed device. Atomic force microscopy images clearly revealed nanoscale sea-island structures on the surface. The strength, rate, and quality of cell adhesion and detachment on the prepared surface were modulated by changes in temperature across the lower critical solution temperature range of PIPAAm molecules. In addition, a two-dimensional cell structure (cell sheet) was successfully recovered on the optimized surfaces. These unique PIPAAm surfaces may be useful for controlling the strength of cell adhesion and detachment.

Nanoscaled sea-island surfaces composed of thermoresponsive block copolymers were fabricated by the Langmuir-Schaefer method for controlling spontaneous cell adhesion and detachment. Both the preparation of the surface and the adhesion and detachment of cells on the surface were visualized.

Preparación de Superficies de respuesta térmica nanoestructurados para la Ingeniería de Tejidos

Thermoresponsive poly(N-isopropylacrylamide) (PIPAAm)-immobilized surfaces for controlling cell adhesion and detachment were fabricated by the ...

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.

Preparación de geles de colágeno en 3D y microcanales para el estudio de las interacciones 3D<em&gt; En Vivo</em

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

A Facile and Eco-friendly Route to Fabricate Poly(Lactic Acid) Scaffolds with Graded Pore Size

Over the recent years, functionally graded scaffolds (FGS) gaineda crucial role for manufacturing of devices for tissue engineering. The importance of this new field of biomaterials research is due to the necessity to develop implants capable of mimicking the complex functionality of the various tissues, including a continuous change from one structure or composition to another. In this latter context, one topic of main interest concerns the design of appropriate scaffolds for bone-cartilage interface tissue. In this study, three-layered scaffolds with graded pore size were achieved by melt mixing poly(lactic acid) (PLA), sodium chloride (NaCl) and polyethylene glycol (PEG). Pore size distributions were controlled by NaCl granulometry and PEG solvation. Scaffolds were characterized from a morphological and mechanical point of view. A correlation between the preparation method, the pore architecture and compressive mechanical behavior was found. The interface adhesion strength was quantitatively evaluated by using a custom-designed interfacial strength test. Furthermore, in order to imitate the human physiology, mechanical tests were also performed in phosphate buffered saline (PBS) solution at 37 &#176;C. The method herein presented provides a high control of porosity, pore size distribution and mechanical performance, thus offering the possibility to fabricate three-layered scaffolds with tailored properties by following a simple and eco-friendly route.

A Facile and Eco-friendly Route to Fabricate PolyLactic Acid Scaffolds with Graded Pore Size

In this work, poly(lactic acid)/polyethylene glycol (PLA/PEG) scaffolds were prepared by using a combination of melt mixing and selective leaching. The method herein discussed permitted to develop three-layer scaffolds by highly controlling both porosity and pore size. The mechanical properties were also evaluated in a physiological environment.

Un Facile y respetuoso del medio ambiente de ruta para la fabricación de poli (ácido láctico) Los andamios con graduado Tamaño de poro

Over the recent years, functionally graded scaffolds (FGS) gaineda crucial role for manufacturing of devices for tissue engineering. The importance of ...

Site-Directed Immobilization of Bone Morphogenetic Protein 2 to Solid Surfaces by Click Chemistry

Different therapeutic strategies for the treatment of non-healing long bone defects have been intensively investigated. Currently used treatments present several limitations that have led to the use of biomaterials in combination with osteogenic growth factors, such as bone morphogenetic proteins (BMPs). Commonly used absorption or encapsulation methods require supra-physiological amounts of BMP2, typically resulting in a so-called initial burst release effect that provokes several severe adverse side effects. A possible strategy to overcome these problems would be to covalently couple the protein to the scaffold. Moreover, coupling should be performed in a site-specific manner in order to guarantee a reproducible product outcome. Therefore, we created a BMP2 variant, in which an artificial amino acid (propargyl-L-lysine) was introduced into the mature part of the BMP2 protein by codon usage expansion (BMP2-K3Plk). BMP2-K3Plk was coupled to functionalized beads through copper catalyzed azide-alkyne cycloaddition (CuAAC). The biological activity of the coupled BMP2-K3Plk was proven in vitro and the osteogenic activity of the BMP2-K3Plk-functionalized beads was proven in cell based assays. The functionalized beads in contact with C2C12 cells were able to induce alkaline phosphatase (ALP) expression in locally restricted proximity of the bead. Thus, by this technique, functionalized scaffolds can be produced that can trigger cell differentiation towards an osteogenic lineage. Additionally, lower BMP2 doses are sufficient due to the controlled orientation of site-directed coupled BMP2. With this method, BMPs are always exposed to their receptors on the cell surface in the appropriate orientation, which is not the case if the factors are coupled via non-site-directed coupling techniques. The product outcome is highly controllable and, thus, results in materials with homogeneous properties, improving their applicability for the repair of critical size bone defects.

Biomaterials doped with Bone Morphogenetic Protein 2 (BMP2) have been used as a new therapeutic strategy to heal non-union bone fractures. To overcome side effects resulting from an uncontrollable release of the factor, we propose a new strategy to site-directly immobilize the factor, thus creating materials with improved osteogenic capabilities.

Dirigida la inmovilización de la proteína ósea morfogenética 2 a superficies sólidas por química del tecleo

Different therapeutic strategies for the treatment of non-healing long bone defects have been intensively investigated. Currently used treatments present ...