Bu çalışma Fransa Institut Curie, Paris, tarafından kurulmuştur. Mekanik sedye Damien Cuvelier (Institut Curie) tarafından tasarlanan ve Grem tarafından üretilen (mecanique-grem.com). PDMS desenleme Ammar Azioune (Bordeaux II Üniversitesi) tarafından geliştirilmiştir.

1.. PDMS pasivasyon <ol><li> PDMS bir parça kesin yaklaşık olarak önceden yapılmış tabakasından x 20 mm 35 mm (örneğin, GelPak, malzeme tabloda listelenen gibi). </li><li> Plastik üst ve alt koruma tabakaları çıkarın (gerekli ise) ve Petri çanağı (muamele edilmiş kültür hücre) bir plastik PDMS yerleştirmek için cımbız kullanın. </li><li> / Dakika 30 salınım ile bir karıştırıcı üzerine 5 dakika için% 70 etanol ile PDMS yıkayın. </li><li> Bunun üzerine akan hava ile yüzeyi kurulayın. </li><li> Yaklaşık 5 cm UV ampullere göre belirli bir mesafede, 5 dakika için derin UV (λ = 180 nm) ile aydınlatma imkanını (lamba referans malzemeleri tabloya bakın; parametreleri farklı lambalar için değişir). </li><li> Her bir parça PDMS için EDC / NHS çözeltisi 200 ul (solüsyonun reaktivitesi saat meselesi çürükleri için bu kullanımdan hemen önce hazırlanmalıdır) hazırlayın. PH 6.0 &#39;da 0.05 M MES + 0.5 M NaCl tampon, 1 ml için, Sülfo-NHS 11.5 mg ve 19.2 mg EDC ekleyin. </li><li> TransferiIşıklı edilmemiştir Petri kabı, bir kapağa Petri kabı PDMS levhalar. Bu PDMS çevresi çok hidrofobik olmasını sağlamak ve bir sonraki adımı kolaylaştıracaktır. </li><li> EDC / NHS solüsyonu ilave edin ve oda sıcaklığında 15 dakika boyunca inkübe edin. </li><li> Su ile EDC / NHS durulayın. </li><li> PLL-PEG-g çözelti (10 mM HEPES pH 8.6 içinde 0.5 mg / ml) ilave edilir ve 3 saat için oda sıcaklığında gece boyunca ikinci inkübe edin. </li><li> Su ile PLL-PEG-g durulayın. (G-PLL-PEG ile işlevselleştirilmiş) pasifleştirilmiş PDMS 4 ° C&#39;de birkaç gün boyunca saklanabilir </li></ol> 2. PDMS desenlendirilmesi <ol><li> PDMS levha alın ve desenlendirme için microfeatures taşıyan bir sentetik kuvars photomask üzerine yerleştirin (bkz. Şekil 1). PLL-g-PEG photomask krom yan bakan taşıyan PDMS tarafını yerleştirin. </li><li> Yaklaşık 5 cm UV ampullere göre belirli bir mesafede, fotomaske yoluyla, 7 dakika boyunca yanar.</li><li> Maske + PDMS üzerine su ekleyin ve yavaş yavaş maske kapalı PDMS soyun. </li><li> Oda sıcaklığında 1 saat süre ile pH 8.6 de HEPES tamponu içinde 50 mg / ml &#39;de fibronektin çözeltisi ile inkübe edin. Bu diğerleri ECM proteinleri kullanmak mümkündür, ancak bunlar bu protokol ile test edilmemiştir. </li><li> PBS ile durulayın. </li></ol> 3. Cihaz montaj <ol><li> Germe cihazı (sorun giderme için Tartışma) üzerine önceden pasifize PDMS monte edin. <ol><li> Sedyenin sabit kısmına PDMS bir tarafı takın. </li><li> PDMS tabakanın çok fazla sıkıştırma olmadan sedyenin mobil kısmına diğer tarafı düzeltildi. </li></ol></li><li> Kalın bir PDMS bıçak içinde PDMS bir dikdörtgen (22 mm x 19 mm) kesme ve (Şekil 2 ye bakınız) hücreleri ve medya koruyacaktır bir havuz (ya da çerçeve) elde etmek için içine bir dikdörtgen kesin. </li><li> Bu havuzu PDMS altında silikon gres ekleyin ve bir med oluşturmak için PDMS levha üstüne yerleştirinyum havuzu muhafaza eder. Yağ germe sırasında PDMS tabaka üzerine havuzun kayma sağlayacaktır. </li></ol> 4. Hücreleri Desenlendirme <ol><li> Versene ile% 50 confluency kültür şişesi hücreleri çıkarın. </li><li> Hücre sayımı ve 200,000 hücre / ml &#39;lik bir konsantrasyonda tekrar süspansiyon bunları. </li><li> Havuzda hücre süspansiyonu 1 ml (ek ayrıntılar için Tartışma) ekleyin. </li><li> Hücreler (RPE-1 hücreleri, 10 dakika ve HeLa hücreleri 20 dakika sürer, hücre tipine bağlı olarak) 10-30 dakika boyunca desen bağlanan olsun. </li><li> Yavaşça dengelenmiş ortamda (inkübatör ortamı dengeye) ile yüzen hücreleri yıkayın. </li><li> Hücreler desenleri birkaç saat boyunca yayalım (RPE-1 en az 2 saat gerekir; HeLa hücreleri 3 saat ihtiyacınız olacak). </li><li> PDMS tatili durumda, buharlaşma ve orta sızıntıyı önlemek için havuz üstünde bir lamel ekleyin. </li><li> Ters bir mikroskop cihazı koymak ve görüntüleme başlar. Immersiyon yağı ob kullanmaktan kaçınınnedeniyle odaklanma sorunları için çalışmaz gibi alamayarak hedeflere ulaşamama riski. </li></ol> 5. Germe <ol><li> X-, y-ve z-ekseni (özellikle x) &#39;de aşama pozisyon düzeltme sırasında mikrometrik vidasını. Aşama pozisyon PDMS genişletme ve odak kaybına karşı koymak için düzeltilmesi gerekmektedir. (TARTIŞMA paragraf &quot;streç sırasında&quot; bak). </li></ol>

<ol>
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Yazarlar herhangi bir mali çıkarlarını beyan.

Bu teknik çok kez kullanılan ve iyice test olmasına rağmen, başarısız bir deney yol açabilir çeşitli kritik adımlar vardır. PDMS Hakkında: Bu iş için, GelPak, piyasada mevcut ince PDMS levha kullanılmıştır. Alternatif PDMS yaprak PDMS karışımı doğrudan döküm alınabilir. Daha tekrarlanabilir ve özel yapılmış PDMS&#39;nin kıyasla kırmak için daha az olasıdır, çünkü GelPak kullanmanızı öneririz. Cihaz ...

Yüksek organizmalarda bir doku oluşturan hücreler mekanik gerilimler ve dış ortamdan ya da çevreleyen hücrelerden 1,2 dan ya geliyor germe güçlerine tabidir. Hücreler uyum ve doku bütünlüğünü korumak için bu güçlere direnmek gerekir. Bu tür güçler de kalkınma 3,4 sırasında dokular morfogenezisi önemlidir. Kültürlü hücreler üzerinde mekanik kuvvet uygulayarak bir doku içinde neler olabileceğini taklit etmek bir yoldur, ancak hücre şekli ve hücre deformasyon 5,6 nicel ve bağımsız kontrolü ile. Bunun için, çeşitli teknikler kullanılabilir. Bir (bütün hücre veya bunun bir parçası), örneğin, AFM veya 7,8 türevleri ya da hücrelerin büyüdüğü alt tabakanın esneme kullanılarak hücreler üzerinde basın olabilir. Bu yazıda anlatılan yöntem hücreleri ile kaplı bir uçak substratı germek için nasıl gösterir. Bu teknik, ilk olarak değerlendirmek için geliştirilmiştir kuvvetlerinin rolü m üzerine uygulananitotic memeli hücreleri 9. Mitotik hücreler geri çekme elyafların yoluyla alt-tabakaya bağlı kalmak ve membran germe da mitotik iğin dönmesini tahrik lifleri üzerine bir kuvvet uygulamıştır. Yapışkan birleştirme micropatterns ve germe kuvvetleri ilgi ve tek tek hücreler şeklinde bağımsız kontrol elde etmektir. Bu, tek eksenli germe uygulanır ise, mükemmel bir şekilde izotropik yuvarlak şekil, bir oval hücre uzatmak için, örneğin mümkündür. Hücreler micropatterns platted değilseniz, tek eksenli en hücreler germe ekseni ile hizalanan uzun bir eksene sahip olan, hücre uzaması sonucu germe. Bu, uzun eksen hizalama ve hücrelere uygulanan gerilme etkisinin etkisini ayırmak için daha sonra zordur. Cihaz, uzun zaman atlamalı floresan mikroskobu da dahil olmak üzere herhangi bir canlı hücre görüntüleme için uygun olan, ve uyuşturucu deney sırasında ilave edilebilir. Derin UV&#39;lerin micropatterning yöntemi 10Azioune ayrıntılı olarak tarif edilmiştir ve ark. PDMS 11 Desen nitelendirildi Azioune et al. 12 de protokol uzanan Mevcut Carpi et al. 13 içeren bir video versiyonu

<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

Mekanik kuvvetler hücreleri üzerinde uygulanan ve / veya dokular, çok sayıda süreçlerinde önemli bir rol oynamaktadır. Bir polidimetilsiloksan görüntüleme ile uyumlu (PDMS) membran üzerine kaplanmıştır hücreleri uzatmak için bir cihaz geliştirdiler. Bu teknik, tekrarlanabilir ve çok yönlüdür. PDMS zar, belirli bir geometri için hücreler veya dokular sınırlandırmak amacıyla micropatterned edilebilir. İlk adım, bir derin UV tekniği ile PDMS membran üzerine micropatterns yazdırmaktır. PDMS zar daha sonra mekanik bir sedye üzerinde monte edilir. A odası boyunca uzanan kayma sağlamak için biyo-uyumlu yağı ile membran üzerine bağlıdır. Hücreler ekildi ve micropatterns birkaç saat boyunca yayılmasına izin verilir. Numune mikrometrik bir vida kullanımı ile birden çok kez gerilmiş gerek gerilmemiş edilebilir. Bu (% 30 civarında) tam ölçüde streç uygulamak için bir dakikadan az sürer. Burada sunulan tekniği için gerekli olan bir motorlu aygıt içermezhızlı bir şekilde ve / veya bilgisayar kontrollü gerilme tekrarlanan germe döngüsünden pplying, ancak bu uygulanabilir. Hücrelerin germe veya doku hücre kuvvetler, mekanik stres veya doku morfolojilerinden hücre yanıtı ile ilgili sorularınız için ilgi olabilir. Bu video sunumu görünüşte basit deney bu tür yaparken ortaya çıkabilecek tipik sorunları önlemek için nasıl gösterecektir.

<html> Bu ekran protokol sunulan teknik mitotik memeli hücrelerinin geri çekme lifleri üzerinde kuvvetlerinin uygulanmasını izin verdi. Gerçekten de, hücre bölünmesi esnasında, mitotik aşamasında, memeli hücreleri bir küre şeklini alır ve alt-tabakaya bağlı olan ince bir zar ile çevrili aktin kabloları geride bırakmak için çekin. Bu kablolar (geri çekilme lifler), bölünme girmeden önce hücre geometri hafızası vardır. PDMS ince film bir fotomaske aracılığıyla derin UV micropatterns yapma...

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

Stretching Micropatterned Cells on a PDMS Membrane

Bu el yazması tek yönlü germe kullanarak yapışık hücreler ve dokular üzerindeki kuvvetleri uygulamak ya da serbest bırakmak için bir teknik sunuyor.

PDMS Zarında Micropatterned Hücreler germe

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 Görüntüleme.  Institut Curie.  Bu el yazması tek yönlü germe kullanarak yapışık hücreler ve dokular üzerindeki kuvvetleri uygulamak ya da serbest bırakmak için bir teknik sunuyor. 

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.

Micropatterned Yüzeyler Kanser Hücreleri ile Hyaluronik Asit Etkileşimleri Eğitim

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

Biyomühendislik

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.

İlaç Etkisi Micropatterned Hücreler Geliştirilmiş Görselleştirme ve Kantitatif Analiz

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

Stretching Short Sequences of DNA with Constant Force Axial Optical Tweezers

Single-molecule techniques for stretching DNA of contour lengths less than a kilobase are fraught with experimental difficulties. However, many interesting biological events such as histone binding and protein-mediated looping of DNA1,2, occur on this length scale. In recent years, the mechanical properties of DNA have been shown to play a significant role in fundamental cellular processes like the packaging of DNA into compact nucleosomes and chromatin fibers3,4. Clearly, it is then important to understand the mechanical properties of short stretches of DNA. In this paper, we provide a practical guide to a single-molecule optical tweezing technique that we have developed to study the mechanical behavior of DNA with contour lengths as short as a few hundred basepairs.
The major hurdle in stretching short segments of DNA is that conventional optical tweezers are generally designed to apply force in a direction lateral to the stage5,6, (see Fig. 1). In this geometry, the angle between the bead and the coverslip, to which the DNA is tethered, becomes very steep for submicron length DNA. The axial position must now be accounted for, which can be a challenge, and, since the extension drags the microsphere closer to the coverslip, steric effects are enhanced. Furthermore, as a result of the asymmetry of the microspheres, lateral extensions will generate varying levels of torque due to rotation of the microsphere within the optical trap since the direction of the reactive force changes during the extension.
Alternate methods for stretching submicron DNA run up against their own unique hurdles. For instance, a dual-beam optical trap is limited to stretching DNA of around a wavelength, at which point interference effects between the two traps and from light scattering between the microspheres begin to pose a significant problem. Replacing one of the traps with a micropipette would most likely suffer from similar challenges. While one could directly use the axial potential to stretch the DNA, an active feedback scheme would be needed to apply a constant force and the bandwidth of this will be quite limited, especially at low forces.
We circumvent these fundamental problems by directly pulling the DNA away from the coverslip by using a constant force axial optical tweezers7,8. This is achieved by trapping the bead in a linear region of the optical potential, where the optical force is constant-the strength of which can be tuned by adjusting the laser power. Trapping within the linear region also serves as an all optical force-clamp on the DNA that extends for nearly 350 nm in the axial direction. We simultaneously compensate for thermal and mechanical drift by finely adjusting the position of the stage so that a reference microsphere stuck to the coverslip remains at the same position and focus, allowing for a virtually limitless observation period.

We illustrate the use of a constant force axial optical tweezers to explore the mechanical properties of short DNA molecules. By stretching DNA axially, we minimize steric hindrances and artifacts arising in conventional lateral manipulation, allowing us to study DNA molecules as short as ~100 nm.

Sabit Kuvvet Eksenel Optik cımbız ile DNA Kısa Diziler Stretching

Single-molecule techniques for stretching DNA of contour lengths  less than a kilobase are fraught with experimental difficulties. However, many ...

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.

Hücre ve Doku mechanobiology Applications A Novel Germe Platformu

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.

Lüminesans Rezonans Enerji memeli hücrelerinde ifade Membran Proteinleri Konformasyonel Değişiklikleri Eğitim transfer

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.

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.

Poli (ε-kaprolakton) electrospun İplik İnsan Mezenkimal Kök Hücre Ek Optimize

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.

Genetik olarak tadil edilmiş hücre transplantasyonu için Micropatterned kültür plakalarında Sferoid hücrelere karşı gene

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.

Micropatterned Vasküler Musküler İnce Filmlerin Genişletilmiş Kültür mikroakışkan Genipin Biriktirme Tekniği

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.

Micropatterned Makro ölçekli 3D Hücresel Mimarlık Modüler Hidrojel Levhaların İnşaatı

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.

Bir Polidimetilsiloksan (PDMS) Koaksiyel Akış Odak Aygıtı Kullanma Çift Emülsiyon Üretimi

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 ...