Questo lavoro è stato fondato da Institut Curie, Parigi, Francia. La barella meccanico è stato progettato da Damien Cuvelier (Institut Curie) ed è prodotto da GREM (mecanique-grem.com). Il patterning su PDMS è stato sviluppato da Ammar Azioune (Bordeaux II University).

1. Passivazione del PDMS <ol><li> Tagliare un pezzo di PDMS circa 35 mm x 20 mm da una lamiera pre fatta (per esempio, GelPak, come elencato nella tabella dei materiali). </li><li> Rimuovere la parte superiore e gli strati protettivi peggiori di plastica (se necessario) e usare pinzette per posizionare i PDMS in plastica (non COLTURA CELLULARE trattati) piastra Petri. </li><li> Lavare le PDMS con etanolo al 70% per 5 minuti su un agitatore a 30 oscillazioni / min. </li><li> Asciugare la superficie scorre aria su di esso. </li><li> Illuminare con profondo UV (λ = 180 nm) per 5 minuti a una distanza dalle lampade UV di circa 5 cm (vedi scheda Materiali per riferimento lampada; parametri variano per lampade diverse). </li><li> Preparare 200 ml di soluzione di EDC / NHS per ogni pezzo PDMS (deve essere preparata poco prima dell&#39;uso perché la reattività della soluzione decade in pochi hr). Per 1 ml di 0,05 M MES + 0,5 tampone M NaCl a pH 6,0, aggiungere 11,5 mg di Sulfo-SSN e 19,2 mg di EDC. </li><li> Trasferire ilPDMS fogli dal capsula di Petri al coperchio della scatola di Petri, che non è stata illuminata. Questo farà sì che i dintorni di PDMS sono molto idrofobiche e facilitare il passaggio successivo. </li><li> Aggiungere la soluzione di EDC / NHS e incubare per 15 min a temperatura ambiente. </li><li> Sciacquare EDC / NHS con acqua. </li><li> Aggiungere la soluzione PLL-g-PEG (0,5 mg / ml in HEPES 10 mM pH 8,6) e incubare dal 3 ore durante la notte a temperatura ambiente. </li><li> Sciacquare il PLL-g-PEG con acqua. PDMS passivato (funzionalizzati con PLL-g-PEG) possono essere conservati per diversi giorni a 4 ° C. </li></ol> 2. Patterning del PDMS <ol><li> Prendete un foglio PDMS e posizionarlo su una fotomaschera quarzo sintetico recante la microfeatures per patterning (vedi Figura 1). Posizionare il lato PDMS recante il PLL-g-PEG di fronte al lato di cromo del fotomaschera. </li><li> Illuminare per 7 min attraverso la fotomaschera ad una distanza dalle lampade UV di circa 5 cm.</li><li> Aggiungere acqua sulla maschera + PDMS e sbucciare le PDMS lentamente la maschera. </li><li> Incubare con soluzione fibronectina a 50 mg / ml in tampone HEPES a pH 8,6 per 1 ora a temperatura ambiente. E &#39;possibile utilizzare altri proteine ​​ECM, ma questi non sono stati testati con questo protocollo. </li><li> Risciacquare con PBS. </li></ol> 3. Montaggio del dispositivo <ol><li> Montare i PDMS precedenza passivate sul dispositivo di stretching (vedi la discussione per la risoluzione dei problemi). <ol><li> Attaccare un lato delle PDMS alla parte fissa della barella. </li><li> Fissare l&#39;altro lato per la parte mobile della barella senza bloccaggio troppo del foglio PDMS. </li></ol></li><li> Tagliare un rettangolo di PDMS (22 mm x 19 mm) in una spessa PDMS stab e tagliare un altro rettangolo interno in modo da avere una piscina (o frame) che manterrà le cellule e supporti (vedere Figura 2). </li><li> Aggiungere grasso al silicone sotto questo PDMS piscina e posizionarlo sulla parte superiore del foglio PDMS per creare un medium mantenendo piscina. Il grasso permetterà lo scorrimento della piscina sopra il foglio PDMS nella filatura. </li></ol> 4. Patterning celle <ol><li> Staccare le cellule da una confluenza pallone di coltura 50% con Versene. </li><li> Contare le cellule e risospendere alla concentrazione di 200.000 cellule / ml. </li><li> Aggiungere 1 ml di sospensione cellulare in piscina (vedi la discussione per ulteriori dettagli). </li><li> Lasciate che le cellule si legano ai modelli per 10-30 min (a seconda del tipo di cellula, RPE-1 le cellule avranno 10 min e cellule HeLa 20 min). </li><li> Lavare delicatamente le cellule galleggianti con medio equilibrato (equilibrare medio in incubatrice). </li><li> Lasciate che le cellule sparse per qualche ora sui modelli (RPE-1 avrà bisogno di almeno 2 ore; cellule HeLa avranno bisogno di 3 ore). </li><li> Aggiungere un coprioggetto sulla parte superiore della piscina per evitare l&#39;evaporazione e medie perdite nel caso in cui PDMS pause. </li><li> Mettere il dispositivo su un microscopio invertito e iniziare imaging. Evitare l&#39;uso di immersione in olio objectives in quanto non funziona a causa di problemi di messa a fuoco. </li></ol> 5. Allungamento <ol><li> Ruotare la vite micrometrica correggendo la posizione di fase del x-, y-e z-asse (principalmente x). La posizione di fase deve essere corretta per contrastare l&#39;allargamento delle PDMS e la perdita di concentrazione. (Vedere &quot;Durante il tratto&quot; paragrafo nella discussione). </li></ol>

<ol>
	<li>Vogel, V., Sheetz, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Local+force+and+geometry+sensing+regulate+cell+functions.">Local force and geometry sensing regulate cell functions.</a> Nat. Rev. Mol. Cell Biol. 7, 265-275 (2006).</li><li>Terenna, C. R., 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=Physical+mechanisms+redirecting+cell+polarity+and+cell+shape+in+fission+yeast.">Physical mechanisms redirecting cell polarity and cell shape in fission yeast.</a> Curr. Biol. 18 (22), 1748-1753 (2008).</li><li>Guillot, C., Lecuit, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanics+of+epithelial+tissue+homeostasis+and+morphogenesis.">Mechanics of epithelial tissue homeostasis and morphogenesis.</a> Science. 340 (6137), 1185-1189 (2013).</li><li>Bosveld, 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=Mechanical+control+of+morphogenesis+by+Fat/Dachsous/Four-jointed+planar+cell+polarity+pathway.">Mechanical control of morphogenesis by Fat/Dachsous/Four-jointed planar cell polarity pathway.</a> Science. 336 (6082), 724-727 (2012).</li><li>Farhadifar, R., Roper, J. C., Aigouy, B., Eaton, S., Julicher, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+influence+of+cell+mechanics,+cell-cell+interactions,+and+proliferation+on+epithelial+packing.">The influence of cell mechanics, cell-cell interactions, and proliferation on epithelial packing.</a> Curr. Biol. 17, 2095-2104 (2007).</li><li>Rauzi, M., Verant, P., Lecuit, T., Lenne, P. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nature+and+anisotropy+of+cortical+forces+orienting+Drosophila+tissue+morphogenesis.">Nature and anisotropy of cortical forces orienting Drosophila tissue morphogenesis.</a> Nat. Cell Biol. 10, 1401-1410 (2008).</li><li>Mitrossilis, D., 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=Real-time+single-cell+response+to+stiffness.">Real-time single-cell response to stiffness.</a> Proc. Natl. Acad. Sci. U.S.A. 107 (38), 16518-16523 (2010).</li><li>Irimia, D., Charras, G., Agrawal, N., Mitchison, T., Toner, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polar+stimulation+and+constrained+cell+migration+in+microfluidic+channels.">Polar stimulation and constrained cell migration in microfluidic channels.</a> Lab Chip. 12, 1783-1790 (2007).</li><li>Fink, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=External+forces+control+mitotic+spindle+positioning.">External forces control mitotic spindle positioning.</a> Nat. Cell. Biol. 13 (7), 771-778 (2011).</li><li>Azioune, A., Storch, M., Bornens, M., Th&#233;ry, M., Piel, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simple+and+rapid+process+for+single+cell+micro-patterning.">Simple and rapid process for single cell micro-patterning.</a> Lab Chip. 9 (11), 1640-1642 (2009).</li><li>Azioune, A., Carpi, N., Tseng, Q., Th&#233;ry, M., Piel, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Protein+micropatterns:+A+direct+printing+protocol+using+deep+Uvs.">Protein micropatterns: A direct printing protocol using deep Uvs.</a> Methods Cell Biol. 97, 133-146 (2010).</li><li>Azioune, A., 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=Robust+method+for+high-throughput+surface+patterning+of+deformable+substrates.">Robust method for high-throughput surface patterning of deformable substrates.</a> Langmuir. 27 (12), 7349-7352 (2011).</li><li>Carpi, N., Piel, M., Azioun, A., Cuvelier, D., Fink, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Micropatterning+on+silicon+elastomer+(PDMS)+with+deep+UVs.">Micropatterning on silicon elastomer (PDMS) with deep UVs.</a> Protoc. Exch. , (2011).</li><li>Sinha, B., 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=Cells+respond+to+mechanical+stress+by+rapid+disassembly+of+caveolae.">Cells respond to mechanical stress by rapid disassembly of caveolae.</a> Cell. 144 (3), 402-413 (2011).</li></ol>

Gli autori dichiarano interessi finanziari concorrenti.

Sebbene questa tecnica è stata utilizzata numerose volte e viene accuratamente testato, ci sono diversi passaggi critici che possono portare ad un esperimento fallito. Circa il PDMS: Per questo lavoro, GelPak, un foglio sottile PDMS disponibile in commercio, è stato utilizzato. In alternativa, i fogli di PDMS possono essere lanciate direttamente dalla miscela PDMS. Si consiglia di utilizzare GelPak perché è più riproducibile, ed è meno probabilità di rottura ...

Le cellule che compongono un tessuto in organismi superiori sono soggetti a tensioni meccaniche e forze traenti o provenienti dall&#39;ambiente esterno o da cellule circostanti 1,2. Cellule devono adattarsi e resistere a queste forze al fine di mantenere l&#39;integrità del tessuto. Tali forze sono importanti anche per i tessuti morfogenesi durante lo sviluppo 3,4. Applicando forze meccaniche su cellule coltivate è un modo di imitare ciò che potrebbe accadere in un tessuto, ma con un controllo quantitativo e indipendente di forma delle cellule e deformazione cella 5,6. Per questo, possono essere utilizzate diverse tecniche. Si può premere sulle cellule (cellula intera o parte di essa), ad esempio utilizzando AFM o derivati ​​7,8 o allungare il substrato le cellule crescono su. Il metodo descritto in questo documento dimostra come allungare un substrato piano placcato con cellule. Questa tecnica è stato originariamente sviluppato per valutare il ruolo delle forze esercitate su mcellule di mammifero itotic 9. Le cellule mitotiche rimanere connessi al substrato attraverso le fibre di retrazione e stretching membrana esercitata una forza su quelle fibre, che a loro volta hanno provocato la rotazione del fuso mitotico. L&#39;interesse di combinare microdisegnature adesivi e stretching è quello di raggiungere un controllo indipendente delle forze e forma delle singole celle. E &#39;per esempio possibile allungare una cella ovoidale in una forma rotonda perfettamente isotropa, mentre è applicata tratto monoassiale. Se le cellule non sono intrecciata su microdisegnature, stiramento uniassiale risultati in allungamento cellulare, con la maggior parte delle cellule avente un asse longitudinale allineato con l&#39;asse tratto. È poi difficile separare l&#39;effetto dell&#39;allineamento asse lungo e l&#39;effetto del tratto applicata alle cellule. Il dispositivo è adatto per qualsiasi imaging cellulare dal vivo, tra cui la microscopia a fluorescenza lasso di tempo, e la droga può essere aggiunto durante l&#39;esperimento. Il metodo UV micropatterning profondo 10è stato descritto in dettaglio nel Azioune et al. 11 patterning su PDMS è stata descritta in Azioune et al. 12 La presente allungamento protocollo è una versione video di Carpi et al. 13

<table border="0" cellpadding="0" cellspacing="0" width="573">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">GelPak</td>
			<td style="width:71px;">GelPak</td>
			<td style="width:119px;">PF-60-X4</td>
			<td style="width:167px;">Different thickness/stickiness are available. One alternative could be to cast your PDMS yourself.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Silicon grease</td>
			<td style="width:71px;">GE Bayer Silicones</td>
			<td style="width:119px;">Baysilone-Paste</td>
			<td>This one is biocompatible</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Stretching device</td>
			<td style="width:71px;">GREM m&#233;canique</td>
			<td style="width:119px;">Stretcher 2011</td>
			<td></td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:216px;">EDC (N-(3-Dimethylaminopropyl)-N&#8242;-ethylcarbodiimide hydrochloride)</td>
			<td style="width:71px;">Sigma</td>
			<td align="right" style="width:119px;">3450</td>
			<td>Stable 6 months at -20 &#176;C</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">NHS (N-Hydroxysulfosuccinimide sodium salt)</td>
			<td style="width:71px;">Sigma</td>
			<td align="right" style="width:119px;">56485</td>
			<td>Protect from humidity</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Pll-g-peg (PLL(20)-g[3.5]-PEG(2) 20 mg)</td>
			<td style="width:71px;">SurfaceSolutions (Zurich)</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Synthetic Quartz photomask</td>
			<td style="width:71px;">Toppan</td>
			<td style="width:119px;"></td>
			<td>Take standard binary photomask in Quartz</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Fibronectin from bovine plasma</td>
			<td style="width:71px;">Sigma</td>
			<td style="width:119px;">F1141</td>
			<td></td>
		</tr>
	</tbody>
</table>

stretching micropatterned cells on a pdms membrane

Forze meccaniche esercitate sulle cellule e / o tessuti svolgono un ruolo importante in numerosi processi. Abbiamo sviluppato un dispositivo di allungare le cellule placcato su un polidimetilsilossano (PDMS) membrana, compatibile con le immagini. Questa tecnica è riproducibile e versatile. La membrana PDMS può essere micropatterned al fine di limitare cellule o tessuti di una geometria specifica. Il primo passo è stampare microdisegnature sulla membrana PDMS con una tecnica UV profondo. La membrana PDMS è poi montato su un telaio meccanico. Una camera è vincolata in cima alla membrana con grasso biocompatibile per consentire scivolare durante l&#39;allungamento. Le cellule vengono seminate e ha permesso di diffondere per diverse ore sui microdisegnature. Il campione può essere allungato e non deformato più volte con l&#39;uso di una vite micrometrica. Ci vuole meno di un minuto per applicare il tratto per tutta la sua estensione (circa il 30%). La tecnica qui presentata non include un dispositivo motorizzato, che è necessario per unapplying cicli tratto ripetuti rapidamente e / o computer controllato stretching, ma questo può essere attuato. Stretching di cellule o di tessuto può essere di interesse per le questioni relative alle forze cellulari, risposta cellulare allo stress meccanico o morfogenesi dei tessuti. Questa presentazione video mostra come evitare i problemi tipici che potrebbero sorgere quando si fa questo tipo di apparentemente semplice esperimento.

<html> La tecnica presentata in questo protocollo video consentiva l&#39;applicazione di forze sulle fibre di retrazione di cellule di mammifero mitotiche. Infatti, durante la divisione cellulare, allo stadio mitotico, cellule di mammifero ritraggono a prendere la forma di una sfera e di lasciarsi alle spalle i cavi di actina sottili circondate da una membrana che sono attaccati al substrato. Questi cavi (fibre di retrazione), sono la memoria della geometria della cella prima di andare in divisione. Fare microdisegnature...

Watch this Scientific Journal Video about Stretching Micropatterned Cells on a PDMS Membrane at JoVE.com

Stretching Micropatterned Cells on a PDMS Membrane

Questo manoscritto presenta una tecnica per applicare o liberare forze su cellule o tessuti aderenti usando allungamento unidirezionale.

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 ...

stretching-micropatterned-cells-on-a-pdms-membrane

Research

JoVE Journal

Bioengineering

15.2K Views.  Institut Curie.  Questo manoscritto presenta una tecnica per applicare o liberare forze su cellule o tessuti aderenti usando allungamento unidirezionale. 

Video: Stretching Micropatterned Cells on a PDMS Membrane

Micropatterned Surfaces to Study Hyaluronic Acid Interactions with Cancer Cells

Cancer invasion and progression involves a motile cell phenotype, which is under complex regulation by growth factors/cytokines and extracellular matrix (ECM) components within the tumor microenvironment. Hyaluronic acid (HA) is one stromal ECM component that is known to facilitate tumor progression by enhancing invasion, growth, and angiogenesis1. Interaction of HA with its cell surface receptor CD44 induces signaling events that promote tumor cell growth, survival, and migration, thereby increasing metastatic spread2-3. HA is an anionic, nonsulfated glycosaminoglycan composed of repeating units of D-glucuronic acid and D-N-acetylglucosamine. Due to the presence of carboxyl and hydroxyl groups on repeating disaccharide units, native HA is largely hydrophilic and amenable to chemical modifications that introduce sulfate groups for photoreative immobilization 4-5. Previous studies involving the immobilizations of HA onto surfaces utilize the bioresistant behavior of HA and its sulfated derivative to control cell adhesion onto surfaces6-7. In these studies cell adhesion preferentially occurs on non-HA patterned regions.
To analyze cellular interactions with exogenous HA, we have developed patterned functionalized surfaces that enable a controllable study and high-resolution visualization of cancer cell interactions with HA. We utilized microcontact printing (uCP) to define discrete patterned regions of HA on glass surfaces. A "tethering" approach that applies carbodiimide linking chemistry to immobilize HA was used 8. Glass surfaces were microcontact printed with an aminosilane and reacted with a HA solution of optimized ratios of EDC and NHS to enable HA immobilization in patterned arrays. Incorporating carbodiimide chemistry with mCP enabled the immobilization of HA to defined regions, creating surfaces suitable for in vitro applications. Both colon cancer cells and breast cancer cells implicitly interacted with the HA micropatterned surfaces. Cancer cell adhesion occurred within 24 hours with proliferation by 48 hours. Using HA micropatterned surfaces, we demonstrated that cancer cell adhesion occurs through the HA receptor CD44. Furthermore, HA patterned surfaces were compatible with scanning electron microscopy (SEM) and allowed high resolution imaging of cancer cell adhesive protrusions and spreading on HA patterns to analyze cancer cell motility on exogenous HA.

A novel approach that allows the high-resolution analysis of cancer cell interactions with exogenous hyaluronic acid (HA) is described. Patterned surfaces are fabricated by combining carbodiimide chemistry and microcontact printing.

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 ...

Ricerca

Bioingegneria

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 ...

A Novel Stretching Platform for Applications in Cell and Tissue Mechanobiology

Tools that allow the application of mechanical forces to cells and tissues or that can quantify the mechanical properties of biological tissues have contributed dramatically to the understanding of basic mechanobiology. These techniques have been extensively used to demonstrate how the onset and progression of various diseases are heavily influenced by mechanical cues. This article presents a multi-functional biaxial stretching (BAXS) platform that can either mechanically stimulate single cells or quantify the mechanical stiffness of tissues. The BAXS platform consists of four voice coil motors that can be controlled independently. Single cells can be cultured on a flexible substrate that can be attached to the motors allowing one to expose the cells to complex, dynamic, and spatially varying strain fields. Conversely, by incorporating a force load cell, one can also quantify the mechanical properties of primary tissues as they are exposed to deformation cycles. In both cases, a proper set of clamps must be designed and mounted to the BAXS platform motors in order to firmly hold the flexible substrate or the tissue of interest. The BAXS platform can be mounted on an inverted microscope to perform simultaneous transmitted light and/or fluorescence imaging to examine the structural or biochemical response of the sample during stretching experiments. This article provides experimental details of the design and usage of the BAXS platform and presents results for single cell and whole tissue studies. The BAXS platform was used to measure the deformation of nuclei in single mouse myoblast cells in response to substrate strain and to measure the stiffness of isolated mouse aortas. The BAXS platform is a versatile tool that can be combined with various optical microscopies in order to provide novel mechanobiological insights at the sub-cellular, cellular and whole tissue levels.

We present in this article a novel stretching platform that can be used to investigate single cell responses to complex anisotropic biaxial mechanical deformation and quantify the mechanical properties of biological tissues.

Una piattaforma Novel Stretching per applicazioni in cellule e tessuti mechanobiology

Tools that allow the application of mechanical forces to cells and tissues or that can quantify the mechanical properties of biological tissues have ...

Luminescence Resonance Energy Transfer to Study Conformational Changes in Membrane Proteins Expressed in Mammalian Cells

Luminescence Resonance Energy Transfer, or LRET, is a powerful technique used to measure distances between two sites in proteins within the distance range of 10-100 &#197;. By measuring the distances under various ligated conditions, conformational changes of the protein can be easily assessed. With LRET, a lanthanide, most often chelated terbium, is used as the donor fluorophore, affording advantages such as a longer donor-only emission lifetime, the flexibility to use multiple acceptor fluorophores, and the opportunity to detect sensitized acceptor emission as an easy way to measure energy transfer without the risk of also detecting donor-only signal. Here, we describe a method to use LRET on membrane proteins expressed and assayed on the surface of intact mammalian cells. We introduce a protease cleavage site between the LRET fluorophore pair. After obtaining the original LRET signal, cleavage at that site removes the specific LRET signal from the protein of interest allowing us to quantitatively subtract the background signal that remains after cleavage. This method allows for more physiologically relevant measurements to be made without the need for purification of protein.

We describe here an improved Luminescence Resonance Energy Transfer (LRET) method where we introduce a protease cleavage site between the donor and acceptor fluorophore sites. This modification allows us to obtain specific LRET signals arising from membrane proteins of interest, allowing for the study of membrane proteins without protein purification.

Luminescence Resonance Energy Transfer allo Studio conformazionale Cambiamenti nella membrana proteine ​​espresse in cellule di mammifero

Luminescence Resonance Energy Transfer, or LRET, is a powerful technique used to measure distances between two sites in proteins within the distance range ...

Optimizing Attachment of Human Mesenchymal Stem Cells on Poly(&#949;-caprolactone) Electrospun Yarns

Research into biomaterials and tissue engineering often includes cell-based in vitro investigations, which require initial knowledge of the starting cell number. While researchers commonly reference their seeding density this does not necessarily indicate the actual number of cells that have adhered to the material in question. This is particularly the case for materials, or scaffolds, that do not cover the base of standard cell culture well plates. This study investigates the initial attachment of human mesenchymal stem cells seeded at a known number onto electrospun poly(&#949;-caprolactone) yarn after 4 hr in culture. Electrospun yarns were held within several different set-ups, including bioreactor vessels rotating at 9 rpm, cell culture inserts positioned in low binding well plates and polytetrafluoroethylene (PTFE) troughs placed within petri dishes. The latter two were subjected to either static conditions or positioned on a shaker plate (30 rpm). After 4 hr incubation at 37&#160;oC, 5% CO2, the location of seeded cells was determined by cell DNA assay. Scaffolds were removed from their containers and placed in lysis buffer. The media fraction was similarly removed and centrifuged &#8211; the supernatant discarded and pellet broken up with lysis buffer. Lysis buffer was added to each receptacle, or well, and scraped to free any cells that may be present. The cell DNA assay determined the percentage of cells present within the scaffold, media and well fractions. Cell attachment was low for all experimental set-ups, with greatest attachment (30%) for yarns held within cell culture inserts and subjected to shaking motion. This study raises awareness to the actual number of cells attaching to scaffolds irrespective of the stated cell seeding density.

Optimizing Attachment of Human Mesenchymal Stem Cells on Poly(&amp;#949;-caprolactone) Electrospun Yarns

This article describes a range of set-ups for seeding human mesenchymal stem cells onto materials, in this case electrospun yarns, that do not cover the base of standard culture well plates in order to maximize and quantify the number of cells that initially attach compared to the known seeding density.

Ottimizzare Allegato di cellule staminali mesenchimali umane su Poli (ε-caprolattone) elettrofilate Filati

Research into biomaterials and tissue engineering often includes cell-based in vitro investigations, which require initial knowledge of the starting cell ...

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. ...

Microfluidic Genipin Deposition Technique for Extended Culture of Micropatterned Vascular Muscular Thin Films

The chronic nature of vascular disease progression requires the development of experimental techniques that simulate physiologic and pathologic vascular behaviors on disease-relevant time scales. Previously, microcontact printing has been used to fabricate two-dimensional functional arterial mimics through patterning of extracellular matrix protein as guidance cues for tissue organization. Vascular muscular thin films utilized these mimics to assess functional contractility. However, the microcontact printing fabrication technique used typically incorporates hydrophobic PDMS substrates. As the tissue turns over the underlying extracellular matrix, new proteins must undergo a conformational change or denaturing in order to expose hydrophobic amino acid residues to the hydrophobic PDMS surfaces for attachment, resulting in altered matrix protein bioactivity, delamination, and death of the tissues.
Here, we present a microfluidic deposition technique for patterning of the crosslinker compound genipin. Genipin serves as an intermediary between patterned tissues and PDMS substrates, allowing cells to deposit newly-synthesized extracellular matrix protein onto a more hydrophilic surface and remain attached to the PDMS substrates. We also show that extracellular matrix proteins can be patterned directly onto deposited genipin, allowing dictation of engineered tissue structure. Tissues fabricated with this technique show high fidelity in both structural alignment and contractile function of vascular smooth muscle tissue in a vascular muscular thin film model. This technique can be extended using other cell types and provides the framework for future study of chronic tissue- and organ-level functionality.

We present a method for microfluidic deposition of patterned genipin and fibronectin on PDMS substrates, allowing extended viability of vascular smooth muscle cell-dense tissues. This tissue fabrication method is combined with previous vascular muscular thin film technology to measure vascular contractility over disease-relevant time courses.

Microfluidic genipina Deposizione Tecnica per la cultura estesa di micropatterned vascolari muscolari Thin Films

The chronic nature of vascular disease progression requires the development of experimental techniques that simulate physiologic and pathologic vascular ...

Construction of Modular Hydrogel Sheets for Micropatterned Macro-scaled 3D Cellular Architecture

Hydrogels can be patterned at the micro-scale using microfluidic or micropatterning technologies to provide an in vivo-like three-dimensional (3D) tissue geometry. The resulting 3D hydrogel-based cellular constructs have been introduced as an alternative to animal experiments for advanced biological studies, pharmacological assays and organ transplant applications. Although hydrogel-based particles and fibers can be easily fabricated, it is difficult to manipulate them for tissue reconstruction. In this video, we describe a fabrication method for micropatterned alginate hydrogel sheets, together with their assembly to form a macro-scale 3D cell culture system with a controlled cellular microenvironment. Using a mist form of the calcium gelling agent, thin hydrogel sheets are easily generated with a thickness in the range of 100 - 200 &#181;m, and with precise micropatterns. Cells can then be cultured with the geometric guidance of the hydrogel sheets in freestanding conditions. Furthermore, the hydrogel sheets can be readily manipulated using a micropipette with an end-cut tip, and can be assembled into multi-layered structures by stacking them using a patterned polydimethylsiloxane (PDMS) frame. These modular hydrogel sheets, which can be fabricated using a facile process, have potential applications of in vitro drug assays and biological studies, including functional studies of micro- and macrostructure and tissue reconstruction.

We describe the fabrication of micropatterned hydrogel sheets using a simple process, which can be assembled and manipulated in a freestanding form. Using these modular hydrogel sheets, a simple macro-scaled 3D cell culture system can be generated with a controlled cellular microenvironment.

Costruzione di fogli modulare idrogel per micropatterned macro-scala 3D Cellular Architettura

Hydrogels can be patterned at the micro-scale using microfluidic or micropatterning technologies to provide an in vivo-like three-dimensional (3D) tissue ...

Double Emulsion Generation Using a Polydimethylsiloxane (PDMS) Co-axial Flow Focus Device

Double emulsions are useful in a number of biological and industrial applications in which it is important to have an aqueous carrier fluid. This paper presents a polydimethylsiloxane (PDMS) microfluidic device capable of generating water/oil/water double emulsions using a coaxial flow focusing geometry that can be fabricated entirely using soft lithography. Similar to emulsion devices using glass capillaries, double emulsions can be formed in channels with uniform wettability and with dimensions much smaller than the channel sizes. Three dimensional flow focusing geometry is achieved by casting a pair of PDMS slabs using two layer soft lithography, then mating the slabs together in a clamshell configuration. Complementary locking features molded into the PDMS slabs enable the accurate registration of features on each of the slab surfaces. Device testing demonstrates formation of double emulsions from 14 &#181;m to 50 &#181;m in diameter while using large channels that are robust against fouling and clogging.

Double Emulsion Generation Using a Polydimethylsiloxane PDMS Co-axial Flow Focus Device

Microfluidic double emulsions generation typically involves devices with patterned wettability or custom-fabricated glass components. Here we describe the fabrication and testing of an all polydimethylsiloxane (PDMS) double emulsion generator that does not require surface treatment or complicated fabrication processes, and is capable of producing double emulsions down to 14 &#181;m.

Doppia Emulsione Generazione Utilizzando un Polidimetilsilossano (PDMS) coassiale flusso fuoco Dispositivo

Double emulsions are useful in a number of biological and industrial applications in which it is important to have an aqueous carrier fluid. This paper ...

Treatment of Ligament Constructs with Exercise-conditioned Serum: A Translational Tissue Engineering Model

In vitro experiments are essential to understand biological mechanisms; however, the gap between monolayer tissue culture and human physiology is large, and translation of findings is often poor. Thus, there is ample opportunity for alternative experimental approaches. Here we present an approach in which human cells are isolated from human anterior cruciate ligament tissue remnants, expanded in culture, and used to form engineered ligaments. Exercise alters the biochemical milieu in the blood such that the function of many tissues, organs and bodily processes are improved. In this experiment, ligament construct culture media was supplemented with experimental human serum that has been &#39;conditioned&#39; by exercise. Thus the intervention is more biologically relevant since an experimental tissue is exposed to the full endogenous biochemical milieu, including binding proteins and adjunct compounds that may be altered in tandem with the activity of an unknown agent of interest. After treatment, engineered ligaments can be analyzed for mechanical function, collagen content, morphology, and cellular biochemistry. Overall, there are four major advantages versus traditional monolayer culture and animal models, of the physiological model of ligament tissue that is presented here. First, ligament constructs are three-dimensional, allowing for mechanical properties (i.e., function) such as ultimate tensile stress, maximal tensile load, and modulus, to be quantified. Second, the enthesis, the interface between boney and sinew elements, can be examined in detail and within functional context. Third, preparing media with post-exercise serum allows for the effects of the exercise-induced biochemical milieu, which is responsible for the wide range of health benefits of exercise, to be investigated in an unbiased manner. Finally, this experimental model advances scientific research in a humane and ethical manner by replacing the use of animals, a core mandate of the National Institutes of Health, the Center for Disease Control, and the Food and Drug Administration.

We present a model of ligament tissue in which three-dimensional constructs are treated with the human exercise-conditioned serum and analyzed for collagen content, function, and cellular biochemistry.

Trattamento delle strutture ligamentali con serum esercitato-condizionato: un modello di ingegneria tessuto transazionale

In vitro experiments are essential to understand biological mechanisms; however, the gap between monolayer tissue culture and human physiology is large, ...

Methods Article

Stretching celle micropatterned su una membrana PDMS