Gli autori riconoscono l&#39;uso del laboratorio di analisi di superficie presso la Johns Hopkins, finanziato nell&#39;ambito della Ricerca Scientifica Materiali e Ingegneria Centro attraverso la National Science Foundation. LED è un tirocinante IGERT e un National Science Foundation Graduate Fellow. Questa ricerca è stata in parte sostenuto da NIH concedere U54CA143868.

1. Fotolitografia standard per la fabbricazione Timbro Micropatterned <ol><li> Risciacquare un wafer di silicio nuovo con etanolo e asciugare con flusso d&#39;aria. Utilizzare pinze wafer e prevenire i difetti superficiali durante l&#39;intero processo. </li><li> Trasferimento wafer a girare verniciatore e coprire superficie del wafer con SU-2025 photoresist negativo. Coprire almeno l&#39;80% dei wafer con photoresist. Cappotto Spin per 10 secondi a 600rpm, seguito da 30 secondi a 3000rpm. A causa della fotosensibilità del photoresist, spegnere le luci della stanza da questo punto in avanti. </li><li> Trasferimento photoresist wafer al silicio a piastra calda per &quot;soft-bake&quot; a 95 ° C per 3 minuti. Togliere dal fornello e lasciare 1 minuto per raffreddare. </li><li> Posizionare un prefabbricato maschera con il modello voluto sulla parte superiore del photoresist coperte wafer di silicio ed esporre ai raggi ultravioletti (UV) irradiazione (350-450 nm) per 20 secondi. </li><li> Trasferimento wafer di silicio a piastra calda per &quot;hard-bake&quot; a 110 ° C per 6 minuti. </li><li> Accendere le luci e rimuovere wafer da piastra riscaldante. Modelli distinti dovrebbe essere visibile a questo punto. </li><li> Risciacquare accuratamente wafer di silicio con SU-8 sviluppatore photoresist. Dopo 3 lavaggi con soluzione di sviluppo, risciacquare con etanolo. Se qualche residuo bianco è presente, ripetere sciacquare con soluzione di sviluppo photoresist, o semplicemente immergere il wafer in soluzione di sviluppo per 2 minuti e procedere di nuovo con etanolo risciacquare. Lavare con acqua e aria secca. </li><li> Mix polidimetilsilossano (PDMS) soluzione elastomero e catalizzatore in un rapporto di 10:1 peso. Centrifugare a 900rpm per 5 minuti per rimuovere le bolle d&#39;aria. </li><li> Luogo fantasia wafer in piastra di Petri e versare PDMS su wafer di silicio. Se ci sono bolle presenti, mettere in desicator e vuoto per un paio di minuti fino a quando bolle scompaiono. </li><li> Cure notte a temperatura ambiente (RT) per formare un timbro complementare elastomerico. PDMS se non è completamente guarito dopo 12 ore, mettere in forno a 60 ° C per 30 minuti. </li><li> Rimuovere con attenzione PDMS da wafer di silicio. Utilizzare un bordo di rasoio per tagliare timbro alla misura desiderata. Sonicare in etanolo per 15 minuti. Wafer può essere utilizzato più volte per creare nuovi francobolli elastomerico. </li></ol> 2. HA micropatterning <ol><li> Plasma vetro pulito i vetrini per 5 minuti. Mettere tutti i vetrini in camera e vuoto per 5 minuti. Quindi consentire a basso flusso di ossigeno di entrare camera. Accendere più pulito al plasma per 5 minuti. Togliere dal più pulito al plasma e posto in una piastra di Petri con pinze. </li><li> Durante la pulizia al plasma, sonicare francobolli PDMS in etanolo per 15 minuti. </li><li> Preparare una fresca 3% v / v soluzione di 3-aminopropyltrimethoxysilane (APTMS) nel 95% v / v di etanolo in una provetta da centrifuga 15 mL. Lasciare agire per 5 minuti a temperatura ambiente per formare un silanolo. </li><li> Luogo timbro PDMS modello-up, spin coater mandrino e coprire fantasia superficie con una soluzione APTMS. Spincoat a 3500rpm per 30 secondi. Non toccare la superficie del francobollo, solo i lati del timbro PDMS. </li><li> Trasferire la soluzione APTMS al plasma pulire superfici vetrate: timbro set rivolto verso il basso su una delle estremità del lato a motivi geometrici e scivolano dolcemente premendo PDMS in modo che sia completamente a contatto con la superficie del vetro per 1 minuto. </li><li> Rimuovere PDMS timbro delicatamente, e consentire vetrino fantasia ad incubare a RT per 30 minuti. Sciacquare superficie lavorata con etanolo e aria secca. Sonicare PDMS bollo per 15 minuti per rimuovere APTMS in eccesso. </li><li> Superfici di calore nel forno o sulla piastra calda per 1 ora a 115 ° C. Sciacquare con etanolo e asciugare con aria. </li><li> Preparare fresca polietilene glicole (PEG)-silano soluzione del 20% v / v 2 - [metossi (polyethyleneoxy) propil] trimetossisilano in toluene. Questo servirà come un non-adesivo regione circostante modelli. </li><li> Trasferimento vetrino fantasia per un piatto di vetro Petri e incubare PEG-silano soluzione per 45 minuti a 75 ° C su una piastra calda. Risciacquare con toluene, l&#39;acqua e asciugare con aria. </li><li> Sterilizzare per 1 ora con irradiazione UV germicida in una cappa di sicurezza biologica. Procedere in cappa di sicurezza biologica da questo punto in avanti per mantenere la sterilità. </li><li> Preparare una soluzione acquosa sterile HA. 10mM di 1-etil-3-(3-dimetilamminopropil) carbodiimmide (EDC) 5mm di N-hydroxysuccinimide 50μg / mL marcato con fluoresceina HA </li><li> Applicare la soluzione HA substrati di vetro per la fantasia in condizioni sterili e protetto dalla luce. Fantasia substrati devono essere indisturbato per 16-24 ore. </li><li> Aspirare off soluzione HA, lavare con soluzione salina tampone fosfato (PBS), e coprire la superficie con 1% di albumina sierica bovina (BSA) in PBS per 1 ora. La superficie è ora pronto per colture cellulari. </li></ol> 3. Coltura cellulare su superfici HA Micropatterned <ol><li> Espandere MDA-MB-231 cellule umane di cancro al seno e LS174T cellule di carcinoma del colon-retto, secondo le istruzioni del produttore. </li><li> Semi di sospensioni cellulari di cellule tumorali con densità compresa tra 0,4 e 1x10 <sup&gt; 6 cellule del cancro al 18,75 centimetri 2 Superficie di vetro di superficie e su HA immobilizzato superfici. Incubare in umidificata incubatore (37 ° C) in atmosfere mantenuto con il 5% di CO 2. L&#39;adesione cellulare dovrebbe avvenire entro 24 ore e può essere osservato con microscopio invertito la luce </li><li> Superfici di colture cellulari possono essere mantenuti fino a 5 giorni in condizioni standard di incubatore. Cambiare i media a giorni alterni. Morfologia cellulare e la crescita può essere osservato con microscopio invertito la luce. Ulteriori test cellulare può essere applicato per analizzare le risposte alla superficie HA. </li></ol> 4. Rappresentante dei risultati: La chimica carbodiimmide utilizzato per immobilizzare covalentemente alla HA APTMS vetrini fantasia è mostrato nella Figura 1A. EDC è di lunghezza zero Reticolante che reagisce con HA gruppi carbossilici per formare ammine reattivi intermedi. Dato che questo intermedio è suscettibile all&#39;idrolisi, NHS viene aggiunto per aumentare l&#39;efficienza carbodiimide reazione. Come soluzione HA interagisce con microdisegni APTMS, una stalla forme ammide legame tra HA intermedi e ammine primarie di ATPMS. Un esempio di superficie HA fantasia visualizzati utilizzando un microscopio a fluorescenza e una intensità di fluorescenza ImageJ analisi dimostrano l&#39;immobilizzazione fantasia di HA sono mostrati (Figura 1B-C). Le superfici micropatterned HA permettere lo studio delle interazioni delle cellule tumorali con HA expgenous. Entrambi MDA-MB-231 materno e LS174t del colon umano linee di cellule tumorali preferenzialmente aderire HA regioni micropatterned (Figura 2). Imaging ad alta risoluzione usando la microscopia elettronica a scansione può essere usato per analizzare le interazioni delle cellule in coltura con superfici HA immobilizzata (Figura 3). <img src="/files/ftp_upload/2413/2413fig1.jpg" alt="Figura 1" /> Figura 1 HA superfici micropatterned (A) Schema che descrive lo sviluppo di superfici HA funzionale, (B) immagine di fluorescenza di fluoresceina (verde)-etichettati HA superficie micropatterned. (C) mappa di distribuzione dei pixel 3D utilizzando il software ImageJ dimostrano i modelli HA discreto. Barra di scala = 100μm. Modificato da 9 con il permesso di Elsevier. <img src="/files/ftp_upload/2413/2413fig2.jpg" alt="Figura 2" /> Figura 2. Adesione delle cellule del cancro in HA superfici micropatterned. Entrambi i due punti (A) e della mammella (B) carcinoma preferenzialmente aderito su patch HA con 24 ore di cultura. Modificato da 9 con il permesso di Elsevier. <img src="/files/ftp_upload/2413/2413fig3.jpg" alt="Figura 3" /> Figura 3. Cellule interazione Cancro con HA. (A) Acquisizione di immagini di microscopia elettronica delle cellule del cancro del colon (A), coltivati ​​su superfici HA mostrato a basso ingrandimento (a sinistra) e ad alto ingrandimento (a destra; di quadrati sulla sinistra) e delle cellule di cancro al seno (B), coltivati ​​su superfici HA mostrato a basso ingrandimento (a sinistra) e ad alto ingrandimento (a destra; di quadrati a sinistra).

<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>

Video figura schematica riprodotto con il permesso; Copyright Wiley-VCH Verlag GmbH &amp; Co. KGaA. Dickinson LE, Kusuma S, Gerecht S. Ricostruire la nicchia differenziazione delle cellule staminali embrionali con biomateriali. Macromolecole. Biosci. 2010; 21 ottobre. [Epub davanti alla stampa].

Il metodo micropatterning HA presentato permette lo studio delle interazioni delle cellule con HA esogeni. HA è nota per svolgere un ruolo chiave nella progressione del cancro 1 Tuttavia ci sono stati studi limitati indagare l&#39;interazione delle cellule tumorali in due dimensioni HA superficie lavorata. Uno studio controllabile sul esogeni microdisegni HA ad alta risoluzione permette la visualizzazione di adesione delle cellule tumorali, la crescita e la migrazione e possono ulteriormente chiarire fondame...

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		<div>
		<table border="1">
		<thead>
		<tr>
		<th>Material Name</th>
		<th>Type</th>
		<th>Company</th>
		<th>Catalogue Number</th>
		<th>Comment</th>
		</tr>
		</thead>
		<tbody>
		
<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>
		</div>

micropatterned surfaces to study hyaluronic acid interactions with cancer cells

Invasione del cancro e nella progressione comporta un fenotipo delle cellule mobili, che è sotto regolamentazione complessa da fattori di crescita / citochine e della matrice extracellulare (ECM) componenti all&#39;interno del microambiente tumorale. L&#39;acido ialuronico (HA) è una componente stromale ECM che è noto per facilitare la progressione del tumore con invasione migliorando, la crescita e l&#39;angiogenesi 1. Interazione di HA con la sua superficie CD44 delle cellule del recettore induce segnalazione di eventi che promuovono la crescita delle cellule tumorali, la sopravvivenza e la migrazione, aumentando così la diffusione metastatica 2-3. HA è uno anionico, glicosamminoglicani nonsulfated composta da unità ripetute di D-glucuronico e DN-acetilglucosamina. A causa della presenza di gruppi carbossilici ed idrossilici sulle unità disaccaride ripetere, HA nativo è in gran parte idrofila e suscettibili di modificazioni chimiche che introducono i gruppi solfato per l&#39;immobilizzazione photoreative 4-5. Gli studi precedenti relativi al immobilizzazioni di HA su superfici utilizzare il comportamento bioresistant di HA e il suo derivato solfato di controllare l&#39;adesione cellulare su superfici 6-7. In questi studi l&#39;adesione cellulare avviene principalmente sulla non-HA regioni fantasia. Per analizzare le interazioni cellulari con HA esogeni, abbiamo sviluppato fantasia superfici funzionalizzate che permettono uno studio controllabile e ad alta risoluzione la visualizzazione delle interazioni delle cellule tumorali con HA. Abbiamo utilizzato stampa microcontact (UCP) per definire le regioni discreta fantasia di HA sulle superfici di vetro. Un approccio &quot;tethering&quot;, che applica la chimica carbodiimmide collegamento a immobilizzare HA è stato usato 8. Superfici vetrate sono state microcontatto stampato con un aminosilane e ha reagito con una soluzione HA di rapporti ottimizzata di EDC e NHS per permettere HA immobilizzazione in array fantasia. Incorporando chimica carbodiimmide con MCP consentito l&#39;immobilizzazione di HA per regioni definite, la creazione di superfici adatte per applicazioni in vitro. Entrambe le cellule del cancro del colon e le cellule cancerogene del seno implicitamente interagito con le superfici micropatterned HA. Adesione delle cellule del cancro si è verificata entro 24 ore con la proliferazione di 48 ore. Utilizzando HA superfici micropatterned, abbiamo dimostrato che l&#39;adesione delle cellule tumorali avviene attraverso il recettore CD44 HA. Inoltre, HA superficie lavorata erano compatibili con la microscopia elettronica a scansione (SEM) e ha permesso di imaging ad alta risoluzione di sporgenze cellula tumorale adesivo e la diffusione su modelli di HA per analizzare la motilità delle cellule tumorali in HA esogeni.

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 nuovo approccio che consente l&#39;analisi ad alta risoluzione delle interazioni delle cellule tumorali con esogeno di acido ialuronico (HA) è descritto. Superficie lavorata sono realizzati mediante la combinazione chimica carbodiimmide e stampa microcontact.

Superfici Micropatterned per studiare le interazioni acido ialuronico con le cellule tumorali

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

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Bioengineering

15.0K Views.  Johns Hopkins University. Un nuovo approccio che consente l'analisi ad alta risoluzione delle interazioni delle cellule tumorali con esogeno di acido ialuronico (HA) è descritto. Superficie lavorata sono realizzati mediante la combinazione chimica carbodiimmide e stampa microcontact.

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 migliore visualizzazione e analisi quantitativa degli effetti del farmaco utilizzando cellule 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 ...

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Bioingegneria

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.

Progettazione di un bioreattore per la pressione ciclica Ex Vivo Studio delle valvole cardiache aortica

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.

Microfluidica Endothelialized per lo studio delle interazioni microvascolari nelle patologie ematologiche

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.

Stretching celle micropatterned su una membrana 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.

Ingegneria dei tessuti del tumore stromale Microenvironment con l&#39;applicazione di Invasion Cancer Cell

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.

Gene Transfection verso Celle sferoide su lastre micropatterned coltura per trapianto di cellule geneticamente modificati

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.

Preparazione di Thermoresponsive Nanostrutturati Superfici Tissue Engineering

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.

Preparazione del 3D collagene Gel e microcanali per lo studio delle interazioni 3D<em&gt; In Vivo</em

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

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 ed ecologico percorso per fabbricare poli (acido lattico) Ponteggi con Graded dimensione dei pori

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.

Site-Directed immobilizzazione della proteina morfogenetica ossea 2 a superfici solide di Click Chemistry

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