Name: a versatile automated platform for micro-scale cell stimulation experiments
Uploaded: 2013-08-06T14:00:00
Description: Watch this Scientific Journal Video about A Versatile Automated Platform for Micro-scale Cell Stimulation Experiments at JoVE.com

Författarna tackar Ronald F. Renzi och Michael S. Bartsch för deras bidrag till utformning och utveckling av DMF enheter och DMF nav. Denna forskning stöds fullt ut av den Riktade Laboratory Forskning och utveckling programmet vid Sandia National Laboratories. Sandia är en multi-program laboratorium förvaltas och drivs av Sandia Corporation, ett helägt dotterbolag till Lockheed Martin Corporation, för US Department of Energy National Nuclear Security Administration under kontrakt DE-AC04-94AL85000.

Denna allmänna protokoll är utformad för att stödja tillämpningen av plattformen till en mängd olika studier, aspekter som är specifika för den representativa studien som beskrivs i denna rapport är separerade i parentes Figur 2 visar en representativ studie som genomförts med hjälp av protokollet.. Notera att i protokollet, alla &quot;instruerar&quot; kommandon automatiseras genom användning av förutbestämda skript. Notera också att steg 2 kan genomföras parallellt med steg 1 (t.ex....

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Vi har utvecklat en enkel och mångsidig automatiserad plattform för mikro-skala cellodling och experiment stimulering. Plattformen gör det möjligt för oss att arbeta med små kulturvolymer och cellpopulationer (1 - 20 l och 100 - 2.000 celler per kammare), kultur storlekar kan minskas ytterligare genom användning av mikrokapillärer av mindre diameter. Att arbeta på dessa skalor minskar kostnaderna för rutinmässiga undersökningar och gör genomförbara studier som kräver användning av dyrbara reagen...

Studien av celler hålls i kultur (in vitro-analys) har gett ovärderlig inblick i de grundläggande principerna och molekylära mekanismer som styr komplexa biologiska system och människors hälsa. De konventionella metoderna för odling, stimulans, och insamling av celler för analys, som utnyttjar petriskålar och mikrotiterplattor, var utformade för studier av stora populationer av celler (≥ 10 5) i milliliter skala kulturvolymer (≥ 0,1 ml). Men det finns många fall där endast begränsade mängder celler finns tillgängliga (t.ex. primära celler), eller små populationer av celler är önskvärda (t.ex. för att reducera cell-till-cell variation bland befolkningen), eller erforderliga reagenser är svårt att få eller oöverkomligt dyr (t.ex. renade cell-utsöndrade faktorer). Sådana frågor kan framgångsrikt behandlas genom nedskalning kultur storlek, som har den extra fördelen att minska förbrukningen av allareagenser som krävs för in vitro-analys 1,2. Tyvärr, konventionell utrustning och metoder stöder inte exakt och reproducerbar manipulation av mikro-skala kulturer och de microfluidics-baserade automatiserade system tillgängliga 3-11 är alltför komplex och specialiserad för rutinmässig användning av de flesta laboratorier. I denna rapport beskriver vi montering och användning av en enkel och mångsidig teknologiplattform för automatiserad kultur, stimulans och återvinning av små populationer av celler (100 - 2000 celler) i mikroskala volymer (1 - 20 pl). Plattformen arkitektur (figur 1) är modulärt uppbyggt: en uppsättning fibronektinbelagda mikrokapillärer (&quot;cell perfusionskammare&quot; modul) tjänar som plats för etablering, underhåll, och stimulering av mikro-skala kulturer, och en digital mikrofluidik (DMF ) 12,13 enheten utrustad med &quot;transfer&quot; mikrokapillärer (&quot;central hub&quot; modul) 14,15 rutter celleroch reagens till och från perfusionskammare. DMF kan användaren individuellt behandla flera droppar samtidigt och att ändra eller åter beställa manipulationer (dvs. konfigurera sampelbehandlingen tåg) utan att ändra enhetens maskinvara. Dess enorma flexibilitet är tydlig i sin växt fram som en viktig teknik i ett brett spektrum av tillämpningar, inklusive cellodling 16,17, analyser enzym 18,19, immunanalyser 20,21, DNA-analys 22,23, protein bearbetning, 24,25 och kliniskt prov bearbetning. 26,27 Vår centrala navet utnyttjar den flexibilitet inneboende till DMF-enheter, och ytterligare förbättrar det genom tillägg av microcapillary gränssnitt, vilket ger möjlighet att genomföra en delmängd av manipulationer (t.ex. cellodling) i specialiserade perifera moduler, snarare än på DMF själva enheten. Uppdelning av bearbetning tåg på detta sätt förenklar också utformningen av PLATForm arkitektur (inget behov av att bygga en DMF enhet som kan utföra alla processteg) och underlättar dess utveckling som nya funktioner krävs (enkelt integrera nya perifera moduler som behövs). Transport av celler och reagenser inom det centrala navet drivs av electrowetting krafter som genereras av sekventiell aktivering av elektroder inom DMF anordningen 13,28, transport till, från och inom perfusionskammare drivs av tryckförändringar som genereras av en hög precision spruta pump. Alla dessa flytande rörelser styrs via ett enkelt elektroniskt gränssnitt och automatiseras genom användning av förutbestämda skript. Som ett representativt exempel visar vi användning av plattformen för studier av transkriptionella responser framkallade i immunceller vid utmaning med bakterier (figur 2). Att utföra dessa experiment på plattformen möjligt för oss att arbeta med ett litet antal celler (~ 1.000 per experimental skick), minimerar experiment till experiment variabilitet, bevara reagenser, och re-direct praktisk arbetskraft. Med tanke på de fördelar det ger, liksom dess tillgänglighet och mångsidighet, bör denna plattform finner användning i en mängd olika laboratorier och tillämpningar och visa sig särskilt användbara för att underlätta analys av celler och stimuli som finns i begränsade mängder.

<table border="1">
 <tbody>
 <tr>
 <td>Name of Reagent/Material</td>
 <td>Company</td>
 <td>Catalog Number</td>
 <td>Comments</td>
 </tr>
 <tr>
 <td>Prelude Direct Lysis Module</td>
 <td>NuGEN</td>
 <td>1400-24</td>
 <td></td>
 </tr>
 <tr>
 <td>Trypan Blue (0.4% w/v)</td>
 <td>GIBCO</td>
 <td>15250-061</td>
 <td></td>
 </tr>
 <tr>
 <td>Cell Stripper</td>
 <td>Cellgro</td>
 <td>25-056-C1</td>
 <td></td>
 </tr>
 <tr>
 <td>Ovation PicoSL WTA</td>
 <td>NuGEN</td>
 <td>3310-048</td>
 <td></td>
 </tr>
 <tr>
 <td>Agencourt RNAClean XP</td>
 <td>Beckman Coulter Genomics</td>
 <td>A63987</td>
 <td></td>
 </tr>
 <tr>
 <td>pHrodo BioParticles</td>
 <td>Invitrogen</td>
 <td>P35361</td>
 <td></td>
 </tr>
 <tr>
 <td>CCL4 TaqMan qRT-PCR assay</td>
 <td>Applied Biosystems</td>
 <td>Mm00443111_m1</td>
 <td></td>
 </tr>
 <tr>
 <td>CCL5 TaqMan qRT-PCR assay</td>
 <td>Applied Biosystems</td>
 <td>Mm01302428_m1</td>
 <td></td>
 </tr>
 <tr>
 <td>PTGS2 TaqMan qRT-PCR assay</td>
 <td>Applied Biosystems</td>
 <td>Mm00478374_m1</td>
 <td></td>
 </tr>
 <tr>
 <td>TNF TaqMan qRT-PCR assay</td>
 <td>Applied Biosystems</td>
 <td>Mm00443258_m1</td>
 <td></td>
 </tr>
 <tr>
 <td>GAPDH TaqMan qRT-PCR assay</td>
 <td>Applied Biosystems</td>
 <td>Mm99999915_g1</td>
 <td></td>
 </tr>
 <tr>
 <td>Pluronic F127</td>
 <td>Sigma Chemical</td>
 <td>2594628</td>
 <td></td>
 </tr>
 <tr>
 <td>Fluorinert FC-40</td>
 <td>Sigma Chemical</td>
 <td>51142-49-5</td>
 <td></td>
 </tr>
 <tr>
 <td>Parylene C dimer</td>
 <td>Specialty Coating Systems</td>
 <td>28804-46-8</td>
 <td></td>
 </tr>
 <tr>
 <td>Teflon-AF</td>
 <td>DuPont</td>
 <td>AF1600</td>
 <td></td>
 </tr>
 <tr>
 <td>Polyimide tape</td>
 <td>ULINE</td>
 <td>S-11928</td>
 <td></td>
 </tr>
 <tr>
 <td>Indium tin oxide (ITO) coated glass substrates </td>
 <td>Delta Technologies </td>
 <td>CB-40IN-1107</td>
 <td></td>
 </tr>
 <tr>
 <td>DMF hub Teflon-coated fused-silica microcapillaries</td>
 <td>Polymicro Technologies</td>
 <td>TSU100375</td>
 <td></td>
 </tr>
 <tr>
 <td>Perfusion chamber microcapillaries</td>
 <td>Polymicro Technologies</td>
 <td>TSP530700</td>
 <td></td>
 </tr>
 <tr>
 <td>Tubing and microcapillary fittings</td>
 <td>Sandia National Laboratories</td>
 <td>&nbsp;</td>
 <td></td>
 </tr>
 <tr>
 <td>Polycarbonate tubing</td>
 <td>Paradigm Optics</td>
 <td>CTPC100-500-5</td>
 <td></td>
 </tr>
 <tr>
 <td>8-port precision syringe pump equipped with 30 mm (500 &mu;l capacity) syringes</td>
 <td>Hamilton Company</td>
 <td>54848-01</td>
 <td></td>
 </tr>
 <tr>
 <td>Parylene-C vapor deposition instrument</td>
 <td>Specialty Coating Systems</td>
 <td>PDS 2010 Labcoter 2</td>
 <td></td>
 </tr>
 <tr>
 <td>High-voltage function generator</td>
 <td>Trek</td>
 <td>615A-1 615-3</td>
 <td></td>
 </tr>
 <tr>
 <td>MVX10 microscope</td>
 <td>Olympus</td>
 <td></td>
 <td>Optional (facilitates tracking of droplets on DMF hub)</td>
 </tr>
 <tr>
 <td>QIClick digital CCD camera</td>
 <td>QImaging</td>
 <td>QIClick-F-CLR-12</td>
 <td>Optional (facilitates tracking of droplets on DMF hub)</td>
 </tr>
</tbody>
</table>

a versatile automated platform for micro-scale cell stimulation experiments

Studie av celler i odling (in vitro-analys) har gett viktig insikt i komplexa biologiska system. Konventionella metoder och utrustning för in vitro-analys är väl lämpade för att studera ett stort antal celler (≥ 10 5) i milliliter skala volymer (≥ 0,1 ml). Men det finns många fall där det är nödvändigt eller önskvärt att skala ner kulturen storlek för att minska förbrukningen av cellerna av intresse och / eller reagens som krävs för deras kultur, stimulans, eller bearbetning. Tyvärr stöder konventionella metoder inte exakt och reproducerbar manipulation av mikro-skala kulturer, och de microfluidicsen-baserade automatiserade system som för närvarande finns tillgängliga är alltför komplex och specialiserad för rutinmässig användning av de flesta laboratorier. För att lösa detta problem, har vi utvecklat en enkel och mångsidig teknologiplattform för automatiserad kultur, stimulans och återvinning av små populationer av celler (100 - 2000 celler) i mikroskala volyms (1 till 20 | il). Plattformen består av en uppsättning fibronektinbelagda mikrokapillärer (&quot;cell perfusionskammare&quot;), inom vilken mikro-skala kulturer upprättas, bevaras och stimuleras, en digital mikrofluidik (DMF)-enhet utrustad med &quot;transfer&quot; mikrokapillärer (&quot;central hub &quot;), som sträckor celler och reagenser till och från perfusionskammare, en hög precision spruta pump, som driver transport av material mellan perfusionskammare och det centrala navet, och ett elektroniskt gränssnitt som ger kontroll över transport av material, vilket är samordnas och automatiseras via förutbestämda skript. Som ett exempel använde vi en plattform för att underlätta studier av transkriptionella de reaktioner i immunceller vid utmaning med bakterier. Användning av plattformen kunde vi minska förbrukningen av celler och reagenser, minimera experiment till experiment variabilitet, och re-direkta praktiska arbete. Med tanke på de fördelar det ger, liksom dess tillgänglighet och mångsidighet, oUR plattform bör finna användning i en mängd olika laboratorier och applikationer, och visa sig särskilt användbara för att underlätta analys av celler och stimuli som finns i begränsade mängder.

Som en demonstration av den automatiserade plattformen, vi använde det för att genomföra en studie där små populationer av immunceller odlades i mikroskala kulturer, utmanas med bakterier, och lyseras för off-plattform analys av pro-inflammatoriska reaktioner (figur 2 ). Var och en av sex kammare cell perfusion ympades med 10 4 immunceller (P388D.1 murina makrofager) återsuspenderades i 10 | il av tillväxtmedium. Efter en vidhäftning period (37 ° C under...

Watch this Scientific Journal Video about A Versatile Automated Platform for Micro-scale Cell Stimulation Experiments at JoVE.com

A Versatile Automated Platform for Micro-scale Cell Stimulation Experiments

Vi har utvecklat en automatiserad cellkultur och förhör plattform för mikro-skala experiment cellstimulering. Plattformen erbjuder enkel, mångsidig och exakt styrning odla och stimulera små populationer av celler, och återhämtar lysates för molekylära analyser. Plattformen lämpar sig väl för studier som använder värdefulla celler och / eller reagens.

En mångsidig automatiserad plattform för mikroskala Experiment cellstimulering

Study of cells in culture (in vitro analysis) has provided important insight into complex biological systems. Conventional methods and equipment for in ...

a-versatile-automated-platform-for-micro-scale-cell-stimulation

Research

JoVE Journal

Bioengineering

Organotypic Collagen I Assay: A Malleable Platform to Assess Cell Behaviour in a 3-Dimensional Context

Cell migration is fundamental to many aspects of biology, including development, wound healing, the cellular responses of the immune system, and metastasis of tumor cells. Migration has been studied on glass coverslips in order to make cellular dynamics amenable to investigation by light microscopy. However, it has become clear that many aspects of cell migration depend on features of the local environment including its elasticity, protein composition, and pore size, which are not faithfully represented by rigid two dimensional substrates such as glass and plastic 1. Furthermore, interaction with other cell types, including stromal fibroblasts 2 and immune cells 3, has been shown to play a critical role in promoting the invasion of cancer cells. Investigation at the molecular level has increasingly shown that molecular dynamics, including response to drug treatment, of identical cells are significantly different when compared in vitro and in vivo 4. 
Ideally, it would be best to study cell migration in its naturally occurring context in living organisms, however this is not always possible. Intermediate tissue culture systems, such as cell derived matrix, matrigel, organotypic culture (described here) tissue explants, organoids, and xenografts, are therefore important experimental intermediates. These systems approximate certain aspects of an in vivo environment but are more amenable to experimental manipulation such as use of stably transfected cell lines, drug treatment regimes, long term and high-resolution imaging. Such intermediate systems are especially useful as proving grounds to validate probes and establish parameters required to image the dynamic response of cells and fluorescent reporters prior to undertaking imaging in vivo 5. As such, they can serve an important role in reducing the need for experiments on living animals.

A method is described for the preparation of a 3-dimensional matrix consisting of collagen type I and primary human fibroblasts. This organotypic gel serves as a useful substrate to assess invasive cell migration because it mimics basic features of tissue stroma and is amenable to many forms of microscopy.

Organotypisk Kollagen I Analys: en formbar plattform att bedöma Cell Beteende i en 3-dimensionell sammanhang

Cell migration is fundamental to many aspects of biology, including development, wound healing, the cellular responses of the immune system, and ...

GENPLAT: an Automated Platform for Biomass Enzyme Discovery and Cocktail Optimization

The high cost of enzymes for biomass deconstruction is a major impediment to the economic conversion of lignocellulosic feedstocks to liquid transportation fuels such as ethanol. We have developed an integrated high throughput platform, called GENPLAT, for the discovery and development of novel enzymes and enzyme cocktails for the release of sugars from diverse pretreatment/biomass combinations. GENPLAT comprises four elements: individual pure enzymes, statistical design of experiments, robotic pipeting of biomass slurries and enzymes, and automated colorimeteric determination of released Glc and Xyl. Individual enzymes are produced by expression in Pichia pastoris or Trichoderma reesei, or by chromatographic purification from commercial cocktails or from extracts of novel microorganisms. Simplex lattice (fractional factorial) mixture models are designed using commercial Design of Experiment statistical software. Enzyme mixtures of high complexity are constructed using robotic pipeting into a 96-well format. The measurement of released Glc and Xyl is automated using enzyme-linked colorimetric assays. Optimized enzyme mixtures containing as many as 16 components have been tested on a variety of feedstock and pretreatment combinations.
GENPLAT is adaptable to mixtures of pure enzymes, mixtures of commercial products (e.g., Accellerase 1000 and Novozyme 188), extracts of novel microbes, or combinations thereof. To make and test mixtures of &tilde;10 pure enzymes requires less than 100 &mu;g of each protein and fewer than 100 total reactions, when operated at a final total loading of 15 mg protein/g glucan. We use enzymes from several sources. Enzymes can be purified from natural sources such as fungal cultures (e.g., Aspergillus niger, Cochliobolus carbonum, and Galerina marginata), or they can be made by expression of the encoding genes (obtained from the increasing number of microbial genome sequences) in hosts such as E. coli, Pichia pastoris, or a filamentous fungus such as T. reesei. Proteins can also be purified from commercial enzyme cocktails (e.g., Multifect Xylanase, Novozyme 188). An increasing number of pure enzymes, including glycosyl hydrolases, cell wall-active esterases, proteases, and lyases, are available from commercial sources, e.g., Megazyme, Inc. (www.megazyme.com), NZYTech (www.nzytech.com), and PROZOMIX (www.prozomix.com).
Design-Expert software (Stat-Ease, Inc.) is used to create simplex-lattice designs and to analyze responses (in this case, Glc and Xyl release). Mixtures contain 4-20 components, which can vary in proportion between 0 and 100%. Assay points typically include the extreme vertices with a sufficient number of intervening points to generate a valid model. In the terminology of experimental design, most of our studies are "mixture" experiments, meaning that the sum of all components adds to a total fixed protein loading (expressed as mg/g glucan). The number of mixtures in the simplex-lattice depends on both the number of components in the mixture and the degree of polynomial (quadratic or cubic). For example, a 6-component experiment will entail 63 separate reactions with an augmented special cubic model, which can detect three-way interactions, whereas only 23 individual reactions are necessary with an augmented quadratic model. For mixtures containing more than eight components, a quadratic experimental design is more practical, and in our experience such models are usually statistically valid.
All enzyme loadings are expressed as a percentage of the final total loading (which for our experiments is typically 15 mg protein/g glucan). For "core" enzymes, the lower percentage limit is set to 5%. This limit was derived from our experience in which yields of Glc and/or Xyl were very low if any core enzyme was present at 0%. Poor models result from too many samples showing very low Glc or Xyl yields. Setting a lower limit in turn determines an upper limit. That is, for a six-component experiment, if the lower limit for each single component is set to 5%, then the upper limit of each single component will be 75%. The lower limits of all other enzymes considered as "accessory" are set to 0%. "Core" and "accessory" are somewhat arbitrary designations and will differ depending on the substrate, but in our studies the core enzymes for release of Glc from corn stover comprise the following enzymes from T. reesei: CBH1 (also known as Cel7A), CBH2 (Cel6A), EG1(Cel7B), BG (&beta;-glucosidase), EX3 (endo-&beta;1,4-xylanase, GH10), and BX (&beta;-xylosidase).
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GENPLAT (GLBRC Enzyme Platform) is an automated platform for discovery and optimization of enzyme cocktails for biomass degradation. It can be adapted to multiple feedstocks and mixtures of enzymes containing multiple components.

GENPLAT: en automatiserad plattform för biomassa Enzyme Discovery och Cocktail optimering

The high cost of enzymes for biomass deconstruction is a major impediment to the economic conversion of lignocellulosic feedstocks to liquid ...

Cell Squeezing as a Robust, Microfluidic Intracellular Delivery Platform

Rapid mechanical deformation of cells has emerged as a promising, vector-free method for intracellular delivery of macromolecules and nanomaterials. This technology has shown potential in addressing previously challenging applications; including, delivery to primary immune cells, cell reprogramming, carbon nanotube, and quantum dot delivery. This vector-free microfluidic platform relies on mechanical disruption of the cell membrane to facilitate cytosolic delivery of the target material. Herein, we describe the detailed method of use for these microfluidic devices including, device assembly, cell preparation, and system operation. This delivery approach requires a brief optimization of device type and operating conditions for previously unreported applications. The provided instructions are generalizable to most cell types and delivery materials as this system does not require specialized buffers or chemical modification/conjugation steps. This work also provides recommendations on how to improve device performance and trouble-shoot potential issues related to clogging, low delivery efficiencies, and cell viability.

Rapid mechanical deformation of cells has emerged as a promising, vector-free method for intracellular delivery of macromolecules and nanomaterials. This protocol provides detailed steps on how to use the system for a broad range of applications.

Cell Klämma som en robust, mikroflödes Intracellular Delivery Platform

Rapid mechanical deformation of cells has emerged as a promising, vector-free method for intracellular delivery of macromolecules and nanomaterials. This ...

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.

A Novel Stretching plattform för tillämpningar inom cell-och vävnads mechanobiology

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

A Microfluidic Platform for High-throughput Single-cell Isolation and Culture

Studying the heterogeneity of single cells is crucial for many biological questions, but is technically difficult. Thus, there is a need for a simple, yet high-throughput, method to perform single-cell culture experiments. Here, we report a microfluidic chip-based strategy for high-efficiency single-cell isolation (~77%) and demonstrate its capability of performing long-term single-cell culture (up to 7 d) and cellular heterogeneity analysis using clonogenic assay. These applications were demonstrated with KT98 mouse neural stem cells, and A549 and MDA-MB-435 human cancer cells. High single-cell isolation efficiency and long-term culture capability are achieved by using different sizes of microwells on the top and bottom of the microfluidic channel. The small microwell array is designed for precisely isolating single-cells, and the large microwell array is used for single-cell clonal culture in the microfluidic chip. This microfluidic platform constitutes an attractive approach for single-cell culture applications, due to its flexibility of adjustable cell culture spaces for different culture strategies, without decreasing isolation efficiency.

Here, we present a protocol for isolating and culturing single cells with a microfluidic platform, which utilizes a new microwell design concept to allow for high-efficiency single cell isolation and long-term clonal culture.

En mikroflödessystem plattform för hög genomströmning Single-cell isolering och kultur

Studying the heterogeneity of single cells is crucial for many biological questions, but is technically difficult. Thus, there is a need for a simple, yet ...

Layered Alginate Constructs: A Platform for Co-culture of Heterogeneous Cell Populations

Many load bearing tissues possess structurally and functionally distinct regions, typically accompanied by different cell phenotypes with differential mechanosensing characteristics. Engineering and analysis of these tissue types remain a challenge. Layered hydrogel constructs provide an opportunity for investigating the interactions among multiple cell populations within single constructs. Alginate hydrogels are both biocompatible and allow for easy isolation of cells after experimentation. Here, we describe a method for the development of small sized dual layered alginate hydrogel discs. This process maintains high cell viability of human mesenchymal stem cells during the formation process and these layered discs can withstand unconfined cyclic compression, commonly used for stimulation of hMSCs undergoing chondrogenesis. These layered constructs can potentially be scaled up to include additional levels, and also be used to segregate cell populations initially after layering. This dual layer alginate hydrogel culture platform can be used for many different applications including engineering and analysis of cells of load bearing tissues and co-cultures of other cell types.

Engineering and analysis of load bearing tissues with heterogeneous cell populations are still a challenge. Here, we describe a method for creating bi-layered alginate hydrogel discs as a platform for co-culture of diverse cell populations within one construct.

Layered alginat Konstruktioner: En plattform för Co-kultur av heterogena cellpopulationer

Many load bearing tissues possess structurally and functionally distinct regions, typically accompanied by different cell phenotypes with differential ...

A High-throughput Cell Microarray Platform for Correlative Analysis of Cell Differentiation and Traction Forces

Microfabricated cellular microarrays, which consist of contact-printed combinations of biomolecules on an elastic hydrogel surface, provide a tightly controlled, high-throughput engineered system for measuring the impact of arrayed biochemical signals on cell differentiation. Recent efforts using cell microarrays have demonstrated their utility for combinatorial studies in which many microenvironmental factors are presented in parallel. However, these efforts have focused primarily on investigating the effects of biochemical cues on cell responses. Here, we present a cell microarray platform with tunable material properties for evaluating both cell differentiation by immunofluorescence and biomechanical cell&#8211;substrate interactions by traction force microscopy. To do so, we have developed two different formats utilizing polyacrylamide hydrogels of varying Young&#39;s modulus fabricated on either microscope slides or glass-bottom Petri dishes. We provide best practices and troubleshooting for the fabrication of microarrays on these hydrogel substrates, the subsequent cell culture on microarrays, and the acquisition of data. This platform is well-suited for use in investigations of biological processes for which both biochemical (e.g., extracellular matrix composition) and biophysical (e.g., substrate stiffness) cues may play significant, intersecting roles.

Cell differentiation is regulated by a host of microenvironmental factors, including both matrix composition and substrate material properties. We describe here a technique utilizing cell microarrays in conjunction with traction force microscopy to evaluate both cell differentiation and biomechanical cell&#8211;substrate interactions as a function of microenvironmental context.

En hög kapacitet Cell microarray plattform för Korrelat analys av celldifferentiering och dragkrafter

Microfabricated cellular microarrays, which consist of contact-printed combinations of biomolecules on an elastic hydrogel surface, provide a tightly ...

A Versatile Method of Patterning Proteins and Cells

Substrate and cell patterning techniques are widely used in cell biology to study cell-to-cell and cell-to-substrate interactions. Conventional patterning techniques work well only with simple shapes, small areas and selected bio-materials. This article describes a method to distribute cell suspensions as well as substrate solutions into complex, long, closed (dead-end) polydimethylsiloxane (PDMS) microchannels using negative pressure. This method enables researchers to pattern multiple substrates including fibronectin, collagen, antibodies (Sal-1), poly-D-lysine (PDL), and laminin. Patterning of substrates allows one to indirectly pattern a variety of cells. We have tested C2C12 myoblasts, the PC12 neuronal cell line, embryonic rat cortical neurons, and amphibian retinal neurons. In addition, we demonstrate that this technique can directly pattern fibroblasts in microfluidic channels via brief application of a low vacuum on cell suspensions. The low vacuum does not significantly decrease cell viability as shown by cell viability assays. Modifications are discussed for application of the method to different cell and substrate types. This technique allows researchers to pattern cells and proteins in specific patterns without the need for exotic materials or equipment and can be done in any laboratory with a vacuum.

This report describes a simple, easy to perform technique, using low pressure vacuum, to fill microfluidic channels with cells and substrates for biological research.

En mångsidig metod för mönstring proteiner och celler

Substrate and cell patterning techniques are widely used in cell biology to study cell-to-cell and cell-to-substrate interactions. Conventional patterning ...

DNA Nanotubes as a Versatile Tool to Study Semiflexible Polymers

Mechanical properties of complex, polymer-based soft matter, such as cells or biopolymer networks, can be understood in neither the classical frame of flexible polymers nor of rigid rods. Underlying filaments remain outstretched due to their non-vanishing backbone stiffness, which is quantified via the persistence length (lp), but they are also subject to strong thermal fluctuations. Their finite bending stiffness leads to unique, non-trivial collective mechanics of bulk networks, enabling the formation of stable scaffolds at low volume fractions while providing large mesh sizes. This underlying principle is prevalent in nature (e.g., in cells or tissues), minimizing the high molecular content and thereby facilitating diffusive or active transport. Due to their biological implications and potential technological applications in biocompatible hydrogels, semiflexible polymers have been subject to considerable study. However, comprehensible investigations remained challenging since they relied on natural polymers, such as actin filaments, which are not freely tunable. Despite these limitations and due to the lack of synthetic, mechanically tunable, and semiflexible polymers, actin filaments were established as the common model system. A major limitation is that the central quantity lp cannot be freely tuned to study its impact on macroscopic bulk structures. This limitation was resolved by employing structurally programmable DNA nanotubes, enabling controlled alteration of the filament stiffness. They are formed through tile-based designs, where a discrete set of partially complementary strands hybridize in a ring structure with a discrete circumference. These rings feature sticky ends, enabling the effective polymerization into filaments several microns in length, and display similar polymerization kinetics as natural biopolymers. Due to their programmable mechanics, these tubes are versatile, novel tools to study the impact of lp on the single-molecule as well as the bulk scale. In contrast to actin filaments, they remain stable over weeks, without notable degeneration, and their handling is comparably straightforward.

Semiflexible polymers display unique mechanical properties that are extensively applied by living systems. However, systematic studies on biopolymers are limited since properties such as polymer rigidity are inaccessible. This manuscript describes how this limitation is circumvented by programmable DNA nanotubes, enabling experimental studies on the impact of filament rigidity.

DNA nanorör som ett mångsidigt verktyg för att studera Semiflexible polymerer

Mechanical properties of complex, polymer-based soft matter, such as cells or biopolymer networks, can be understood in neither the classical frame of ...

A Multilayer Microfluidic Platform for the Conduction of Prolonged Cell-Free Gene Expression

The limitations of cell-based synthetic biology are becoming increasingly apparent as researchers aim to develop larger and more complex synthetic genetic regulatory circuits. The analysis of synthetic genetic regulatory networks in vivo is time consuming and suffers from a lack of environmental control, with exogenous synthetic components interacting with host processes resulting in undesired behavior. To overcome these issues, cell-free characterization of novel circuitry is becoming more prevalent. In vitro transcription and translation (IVTT) mixtures allow the regulation of the experimental environment and can be optimized for each unique system. The protocols presented here detail the fabrication of a multilayer microfluidic device that can be utilized to sustain IVTT reactions for prolonged durations. In contrast to batch reactions, where resources are depleted over time and (by-) products accumulate, the use of microfluidic devices allows the replenishment of resources as well as the removal of reaction products. In this manner, the cellular environment is emulated by maintaining an out-of-equilibrium environment in which the dynamic behavior of gene circuits can be investigated over extended periods of time. To fully exploit the multilayer microfluidic device, hardware and software have been integrated to automate the IVTT reactions. By combining IVTT reactions with the microfluidic platform presented here, it becomes possible to comprehensively analyze complex network behaviors, furthering our understanding of the mechanisms that regulate cellular processes.

The fabrication process of a PDMS-based, multilayer, microfluidic device that allows in vitro transcription and translation (IVTT) reactions to be performed over prolonged periods is described. Furthermore, a comprehensive overview of the hardware and software required to automate and maintain these reactions for prolonged durations is provided.

En Multilayer Microfluidic plattform för ledning av långvarig cell-fri genuttryck

The limitations of cell-based synthetic biology are becoming increasingly apparent as researchers aim to develop larger and more complex synthetic genetic ...