Name: initial 3d cell cluster control in a hybrid gel cube device for repeatable pattern formations
Uploaded: 2019-03-21T14:30:00
Description: Watch this Scientific Journal Video about Initial 3D Cell Cluster Control in a Hybrid Gel Cube Device for Repeatable Pattern Formations at JoVE.com

This work was financially supported by JSPS KAKENHI (18H04765) and the Program to Disseminate Tenure Track System, MEXT, Japan.

1. Fabrication of hybrid gel cube device
<ol>
	<li>Prepare a polycarbonate (PC) cubic frame either by using a machining process or a 3D printer. The size of the PC frame depends on the sample size. In this study, we used a frame of 5 mm on each side so that the branches had sufficient space to elongate during culturing.</li>
	<li>Place the PC frame on a pre-cooled glass slide or another smooth surface in an ice box (&#60;0 &#176;C) (Figure 1A).</li>
	<li>Add 12 &#181;L of pre-heated 1.5% a...

<ol>
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M. P., O&#8217;Brien, L. E., Yu, W., Datta, A., Mostov, K. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Epithelial+polarity+and+tubulogenesis+in+vitro.">Epithelial polarity and tubulogenesis in vitro.</a> Trends in Cell Biology. 13 (4), 169-176 (2003).</li><li>Affolter, M., Bellusci, S., Itoh, N., Shilo, B., Thiery, J. P., Werb, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tube+or+not+tube:+Remodeling+epithelial+tissues+by+branching+morphogenesis.">Tube or not tube: Remodeling epithelial tissues by branching morphogenesis.</a> Developmental Cell. 4 (1), 11-18 (2003).</li><li>Denk, W., Strickler, J., Webb, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Two-photon+laser+scanning+fluorescence+microscopy.">Two-photon laser scanning fluorescence microscopy.</a> Science. 248 (4951), 73-76 (1990).</li><li>Huisken, 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=Optical+Sectioning+Deep+Inside+Live+Embryos+by+Selective+Plane+Illumination+Microscopy.">Optical Sectioning Deep Inside Live Embryos by Selective Plane Illumination Microscopy.</a> Science. , 1007-1009 (2004).</li><li>Hagiwara, M., Kawahara, T., Nobata, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tissue+in+Cube:+In+Vitro+3D+Culturing+Platform+with+Hybrid+Gel+Cubes+for+Multidirectional+Observations.">Tissue in Cube: In Vitro 3D Culturing Platform with Hybrid Gel Cubes for Multidirectional Observations.</a> Advanced Healthcare Materials. 5 (13), 1566-1571 (2016).</li><li>Hagiwara, M., Nobata, R., Kawahara, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Large+Scale+Imaging+by+Fine+Spatial+Alignment+of+Multi-Scanning+Data+with+Gel+Cube+Device.">Large Scale Imaging by Fine Spatial Alignment of Multi-Scanning Data with Gel Cube Device.</a> Applied Sciences. 8 (235), (2018).</li><li>Kolesky, D. B., Homan, K. A., Skylar-Scott, M. A., Lewis, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Three-dimensional+bioprinting+of+thick+vascularized+tissues.">Three-dimensional bioprinting of thick vascularized tissues.</a> Proceedings of the National Academy of Sciences of the United States of America. 113 (12), 3179-3184 (2016).</li><li>Mironov, V., Visconti, R. P., Kasyanov, V., Forgacs, G., Drake, C. J., Markwald, R. 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The method presented in this paper is simple and can be performed without high-technology equipment. Concurrently, a precise cell cluster shape control result in the 3D space of hydrogel can be obtained. After the initial control, the cells can grow in the HGC as much as they are cultured on a dish. The multi-directional imaging is performed by rotating the sample with the HGC using any microscopy system, and it significantly enhances the imaging quality. The choice of the materials for the HGC frame and micromold is fle...

The importance of a 3D culture, which better mimics biological environments than does a 2D culture, is considerably emphasized in cell/tissue culture1,2,3. The interaction between the cells and extracellular matrix (ECM) provides important cues regarding morphogenesis4,5. Many tissue formations can emerge only under 3D environments, such as the folding process6,7, invagination8, and tubular formation9,10. However, numerous difficulties prevent researchers from shifting to 3D experiments from 2D experiments on a dish. One of the major difficulties in 3D experiments is the issue of imaging 3D samples. Compared with planar experiments, acquisition of appropriate 3D images is still challenging in many cases. In particular, obtaining an appropriate 3D image is a difficult task when the sample size reaches the millimeter range owing to the large focal depth of low-magnification lenses. For example, the focal depth reaches more than 50 &#181;m when a 10x magnification lens is used while the size of the single cell is normally less than 10 &#181;m. To enhance the imaging quality, high-technology microscopy systems are being developed (e.g., two-photon microscopy11 and light-sheet microscopy system12), but their availability is limited owing to their expensive price. As an alternative, we have previously developed a hybrid gel cube (HGC) device13. The device consists of two types of hydrogels: agarose as a support gel and an ECM such as collagen or Matrigel as a culture gel. The HGC allows us to collect the sample during culturing and rotate the cube to achieve multi-directional imaging, which addresses the focal depth problem14.
Another difficulty in 3D experiments is their low repeatability owing to the poor controllability of the 3D environments. Unlike a planar culture on a plastic dish, variations in the initial culture conditions easily occur in a 3D space surrounded by a soft material. A significant variation in the experimental results deteriorates the following analysis and masks the underlying mechanisms. Many engineering technologies have been developed to spatially align single cells, such as bioprinting15,16, fiber weaving17, and scaffolding18, but they require complex preprocessing or specifically designed equipment. In contrast, we have developed a methodology for achieving 3D cell alignment in an HGC19.
In this protocol, we illustrated a simple procedure with commonly used equipment for controlling the 3D initial cell cluster shape in an HGC. First, the fabrication process of the HGC was demonstrated. Then, micromolds fabricated by photolithography or a machining process were placed in the HGC to produce a pocket with an arbitrary shape in an ECM. Subsequently, highly dense cells after centrifugation were injected into the pocket to control the initial cell cluster shape in the HGC. The precisely controlled cell cluster could be imaged from many directions because of the HGC. Normal human bronchial epithelial (NHBE) cells were used to demonstrate the control of the initial cell cluster shape and imaging of the branches from multiple directions for enhancing the imaging quality.

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	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">12-well-plate</td>
			<td style="width:124px;">Corning&#160; Inc.</td>
			<td align="right" style="width:132px;">3513</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="26">
			<td height="26" style="height:26px;width:251px;">2-Methoxy-1-methylethyl Acetate</td>
			<td style="width:124px;">FUJIFILM Wako Pure Chemical Co.</td>
			<td style="width:132px;">130-10505</td>
			<td>PGMEA, CAS: 108-65-6&#160;</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:251px;">4% paraformaldehyde</td>
			<td style="width:124px;">FUJIFILM Wako Pure Chemical Co.</td>
			<td style="width:132px;">161-20141</td>
			<td>CAS: 30525-89-4</td>
		</tr>
		<tr height="35">
			<td height="35" style="height:35px;width:251px;">Agarose, low gelling temperature&#160; BioReagent</td>
			<td style="width:124px;">Sigma-Aldrich</td>
			<td style="width:132px;">A9414</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:251px;">Alexa fluor 488 phalloidin</td>
			<td style="width:124px;">Thermo Fisher Scientific</td>
			<td style="width:132px;">A12379</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">AZ1512</td>
			<td>Merck</td>
			<td style="width:132px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">BEGM bullet kit</td>
			<td style="width:124px;">Lonza</td>
			<td style="width:132px;">CC-3170</td>
			<td>Specialized medium for NHBE cells</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:251px;">Bovine Serum Albumin solution (10 %)</td>
			<td style="width:124px;">Sigma-Aldrich</td>
			<td style="width:132px;">A1595</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">EGM-2 bullet kit</td>
			<td style="width:124px;">Lonza</td>
			<td style="width:132px;">CC-3162</td>
			<td>Specialized medium for endothelial cells</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Lipidure</td>
			<td style="width:124px;">NOF co.</td>
			<td style="width:132px;"></td>
			<td>MPC polymer</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:251px;">Matrigel growth factor reduced basement membrane matrix</td>
			<td style="width:124px;">Corning&#160; Inc.</td>
			<td style="width:132px;">354230</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:251px;">Normal Goat Serum (10%)</td>
			<td style="width:124px;">Thermo Fisher Scientific</td>
			<td style="width:132px;">50197Z</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:251px;">Normal human bronchial epithelial cells</td>
			<td style="width:124px;">Lonza</td>
			<td style="width:132px;">CC-2541</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">SILPOT 184 W/C</td>
			<td style="width:124px;">Dow Corning Co.</td>
			<td style="width:132px;">3255981</td>
			<td>Base resin and catalyst for PDMS</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:251px;">SUEX D300</td>
			<td style="width:124px;"></td>
			<td style="width:132px;">DJ MicroLaminates, Inc</td>
			<td>Thick negative photoresist (thichness: 300 mm)</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:251px;">Triton X-100 (1%)</td>
			<td style="width:124px;">Thermo Fisher Scientific</td>
			<td style="width:132px;">HFH10</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:251px;">Trypsin-EDTA (0.25%)</td>
			<td style="width:124px;">Thermo Fisher Scientific</td>
			<td style="width:132px;">25200056</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">TWEEN 20</td>
			<td style="width:124px;">Sigma-Aldrich</td>
			<td style="width:132px;">P9416</td>
			<td></td>
		</tr>
	</tbody>
</table>

initial 3d cell cluster control in a hybrid gel cube device for repeatable pattern formations

The importance of in vitro 3D cultures is considerably emphasized in cell/tissue culture. However, the lack of experimental repeatability is one of its restrictions. Producing few repeatable results of pattern formation deteriorates the analysis of the mechanisms underlying the self-organization. Reducing variation in initial culture conditions, such as the cell density and distribution in the extracellular matrix (ECM), is crucial to enhance the repeatability of a 3D culture. In this article, we demonstrate a simple but robust procedure for controlling the initial cell cluster shape in a 3D extracellular matrix to obtain highly repeatable pattern formations. A micromold with a desired shape was fabricated by using photolithography or a machining process, and it formed a 3D pocket in the ECM contained in a hybrid gel cube (HGC). Highly concentrated cells were then injected in the pocket so that the cell cluster shape matched with the fabricated mold shape. The employed HGC allowed multi-directional scanning by its rotation, which enabled high-resolution imaging and the capture of the entire tissue structure even though a low-magnification lens was used. Normal human bronchial epithelial cells were used to demonstrate the methodology.&#160;

Normal human bronchial epithelial (NHBE) cells were used to demonstrate the illustrated methodology and control the initial collective cell geometry to achieve a cylinder shape and a prism shape, respectively in an ECM environment. The multi-directional imaging results obtained by phase contrast as well as phalloidin staining of a cylinder shape (Figure 4A,B) and the prism shape (Figure 4C,D) are...

Watch this Scientific Journal Video about Initial 3D Cell Cluster Control in a Hybrid Gel Cube Device for Repeatable Pattern Formations at JoVE.com

Initial 3D Cell Cluster Control in a Hybrid Gel Cube Device for Repeatable Pattern Formations

We present a procedure for controlling the initial cell cluster shape in a 3D extracellular matrix to obtain a repeatable pattern formation. A cubic device containing two different hydrogels is employed to achieve multi-directional imaging for tissue pattern formation.

The importance of in vitro 3D cultures is considerably emphasized in cell/tissue culture. However, the lack of experimental repeatability is one of its ...

This protocol uses a simple method for enhancing the reliability of a 3D cell culture model without the use of any special equipment. The main advantage of this technique is that we can conduct the repeatable 3D culture experiment by controlling the initial culture condition within the cubic device. After preparing a five by five millimeter polycarbonate cubic frame, place the frame on a pre cooled slide and an ice box and use a pipette to add 12 microliters of preheated 1.5%agarose from the top face of the cubic frame to the bottom surface.Spread the agarose to obtain a flat surface and allow the polymer to cure. Use tweezers to slide the frame to the edge of the glass and rotate the frame so that the open side is facing down before placing the frame back onto the slide. After filling the next two surfaces of the frame with more agarose, as just demonstrated, drop the agarose into a container from an open face to form an agarose wall on the fourth and fifth sides.To set up an initial cell cluster shape inject an appropriate extracellular matrix for the cell culture of interest into the hybrid gel cube culture space and set a fabricated micro mold onto the cube. Then place the cube in a carbon dioxide incubator for 25 minutes at 37 degrees Celsius. When the extracellular matrix is cured, carefully lift out the micro mold so that the matrix does not deteriorate.A pocket in the desired mold shape will be fabricated in the extracellular matrix. To load the cells concentrate the experimental cell suspension after centrifugation in the appropriate experimental cell culture medium and inject the cells into the pocket within the extracellular matrix. Place the cube into the carbon dioxide incubator for 20 minutes at 37 degrees Celsius to allow the cells to fall into the extracellular matrix pocket, filling the space created by the micro mold.At the end of the incubation, place the cube into one well of a 24 well plate and add 100 microliters of the appropriate cell culture medium to the well. Inject additional extracellular matrix to close the pocket and return the cube to the incubator for 25 minutes. When the extracellular matrix is cured drop approximately 10 microliters of 20 degree Celsius agarose onto the top surface to the cube to close the surface and cure the drop for 10 to 20 minutes at 37 degrees Celsius.Then cover the entire cube with fresh medium to promote osmotic pressure for facilitating the transfer of nutrition to the cells within the cube. For noninvasive 3D shape recognition by multidirectional observation, place the plate onto a microscope stage and obtain images of each side of the cube by bright field or phase contrast microscopy, using tweezers to rotate the cube service to be imaged between captures. For immunofluorescent imaging by multidirectional observation, first aspirate the supernatant from the well containing the cube and fix the cube in 4%paraformaldehyde for 20 minutes at room temperature.At the end of the fixation, wash the cube two times with PBS for 10 minutes per wash. Impermeabilize the cube with 0.5%triton x-100 and PBS for 10 minutes at four degrees Celsius. Next, wash the cube three times in PBS for 10 minutes per wash, before blocking any nonspecific bonding with goat serum and immunofluorescence buffer for 60 minutes at room temperature.Then stain the cells with the appropriate primary antibody of interest according to standard antibody staining protocols. Then image all six sides of the cube on a laser or fluorescent microscope as just demonstrated. In this representative experiment multidirectional imaging of hybrid gel cubes, cultured with normal human bronchial epithelial cells, demonstrates the generation of an initial cylindrical or prism shaped cell culture by phase contrast and immunofluorescent imaging of the cultures.Here immuno staining of normal human epithelial cells initially controlled to a cylindrical shape in the hybrid gel cube, after generation of the bronchial tree is shown. The branches demonstrate the perpendicular to the cylindrical axis, as revealed by multidimensional imaging. It is important to inject a high density of cells into the extracellular matrix pocket, as a low density of cells may result in deterioration of that cell quality after incubation.This method pattern is the repeatable formation of a 3D cellular pattern with a quantitative measurement by multidirectional imaging to study the mechanism of dish development.

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Research

JoVE Journal

Bioengineering

Creating Two-Dimensional Patterned Substrates for Protein and Cell Confinement

Microcontact printing provides a rapid, highly reproducible method for the creation of well-defined patterned substrates.1 While microcontact printing can be employed to directly print a large number of molecules, including proteins,2 DNA,3 and silanes,4 the formation of self-assembled monolayers (SAMs) from long chain alkane thiols on gold provides a simple way to confine proteins and cells to specific patterns containing adhesive and resistant regions. This confinement can be used to control cell morphology and is useful for examining a variety of questions in protein and cell biology. Here, we describe a general method for the creation of well-defined protein patterns for cellular studies.5 This process involves three steps: the production of a patterned master using photolithography, the creation of a PDMS stamp, and microcontact printing of a gold-coated substrate. Once patterned, these cell culture substrates are capable of confining proteins and/or cells (primary cells or cell lines) to the pattern.
The use of self-assembled monolayer chemistry allows for precise control over the patterned protein/cell adhesive regions and non-adhesive regions; this cannot be achieved using direct protein stamping. Hexadecanethiol, the long chain alkane thiol used in the microcontact printing step, produces a hydrophobic surface that readily adsorbs protein from solution. The glycol-terminated thiol, used for backfilling the non-printed regions of the substrate, creates a monolayer that is resistant to protein adsorption and therefore cell growth.6 These thiol monomers produce highly structured monolayers that precisely define regions of the substrate that can support protein adsorption and cell growth. As a result, these substrates are useful for a wide variety of applications from the study of intercellular behavior7 to the creation of microelectronics.8
While other types of monolayer chemistry have been used for cell culture studies, including work from our group using trichlorosilanes to create patterns directly on glass substrates,9 patterned monolayers formed from alkane thiols on gold are straight-forward to prepare. Moreover, the monomers used for monolayer preparation are commercially available, stable, and do not require storage or handling under inert atmosphere. Patterned substrates prepared from alkane thiols can also be recycled and reused several times, maintaining cell confinement.10

Self-assembled monolayers (SAMs) formed from long chain alkane thiols on gold provide well-defined substrates for the formation of protein patterns and cell confinement. Microcontact printing of hexadecanethiol using a polydimethylsiloxane (PDMS) stamp followed by backfilling with a glycol-terminated alkane thiol monomer produces a pattern where protein and cells adsorb only to the stamped hexadecanethiol region.

Microcontact printing provides a rapid, highly reproducible method for the creation of well-defined patterned substrates.1  While microcontact printing ...

Ordering Single Cells and Single Embryos in 3D Confinement: A New Device for High Content Screening

Biological cells are usually observed on flat (2D) surfaces. This condition is not physiological, and phenotypes and shapes are highly variable. Screening based on cells in such environments have therefore serious limitations: cell organelles show extreme phenotypes, cell morphologies and sizes are heterogeneous and/or specific cell organelles cannot be properly visualized. In addition, cells in vivo are located in a 3D environment; in this situation, cells show different phenotypes mainly because of their interaction with the surrounding extracellular matrix of the tissue. In order to standardize and generate order of single cells in a physiologically-relevant 3D environment for cell-based assays, we report here the microfabrication and applications of a device for in vitro 3D cell culture. This device consists of a 2D array of microcavities (typically 105 cavities/cm2), each filled with single cells or embryos. Cell position, shape, polarity and internal cell organization become then normalized showing a 3D architecture. We used replica molding to pattern an array of microcavities, &#8216;eggcups&#8217;, onto a thin polydimethylsiloxane (PDMS) layer adhered on a coverslip. Cavities were covered with fibronectin to facilitate adhesion. Cells were inserted by centrifugation. Filling percentage was optimized for each system allowing up to 80%. Cells and embryos viability was confirmed. We applied this methodology for the visualization of cellular organelles, such as nucleus and Golgi apparatus, and to study active processes, such as the closure of the cytokinetic ring during cell mitosis. This device allowed the identification of new features, such as periodic accumulations and inhomogeneities of myosin and actin during the cytokinetic ring closure and compacted phenotypes for Golgi and nucleus alignment. We characterized the method for mammalian cells, fission yeast, budding yeast, C. elegans with specific adaptation in each case. Finally, the characteristics of this device make it particularly interesting for drug screening assays and personalized medicine.

We report a device and a new method to study cells and embryos. Single cells are precisely ordered in microcavity arrays. Their 3D confinement is a step towards 3D environments encountered in physiological conditions and allows organelle orientation. By controlling cell shape, this setup minimizes variability reported in standard assays.

Biological cells are usually observed on flat (2D) surfaces. This condition is not physiological, and phenotypes and shapes are highly variable. Screening ...

Concentric Gel System to Study the Biophysical Role of Matrix Microenvironment on 3D Cell Migration

The ability of cells to migrate is crucial in a wide variety of cell functions throughout life&#160;from embryonic development and wound healing&#160;to tumor and cancer metastasis. Despite intense research efforts, the basic biochemical and biophysical principles of cell migration are still not fully understood, especially in the physiologically relevant three-dimensional (3D) microenvironments. Here, we describe an in vitro assay designed to allow quantitative examination of 3D cell migration behaviors. The method exploits the cell&#8217;s mechanosensing ability and propensity to migrate into previously unoccupied extracellular matrix (ECM). We use the invasion of highly invasive breast cancer cells, MDA-MB-231, in collagen gels as a model system. The spread of cell population and the migration dynamics of individual cells over weeks of culture can be monitored using live-cell imaging and analyzed to extract spatiotemporally-resolved data. Furthermore, the method is easily adaptable for diverse extracellular matrices, thus offering a simple yet powerful way to investigate the role of biophysical factors in the microenvironment on cell migration.

The mechanical properties and microstructure of the extracellular matrix strongly affect 3D migration of cells. An in vitro method to study the spatiotemporal cell migration behavior in biophysically variable environments, at both population and individual cell levels, is described.

The ability of cells to migrate is crucial in a wide variety of cell functions throughout life&#160;from embryonic development and wound healing&#160;to ...

Preparation of 3D Collagen Gels and Microchannels for the Study of 3D Interactions In Vivo

Historically, most cellular processes have been studied in only 2 dimensions. While these studies have been informative about general cell signaling mechanisms, they neglect important cellular cues received from the structural and mechanical properties of the local microenvironment and extracellular matrix (ECM). To understand how cells interact within a physiological ECM, it is important to study them in the context of 3 dimensional assays. Cell migration, cell differentiation, and cell proliferation are only a few processes that have been shown to be impacted by local changes in the mechanical properties of a 3-dimensional ECM. Collagen I, a core fibrillar component of the ECM, is more than a simple structural element of a tissue. Under normal conditions, mechanical cues from the collagen network direct morphogenesis and maintain cellular structures. In diseased microenvironments, such as the tumor microenvironment, the collagen network is often dramatically remodeled, demonstrating altered composition, enhanced deposition and altered fiber organization. In breast cancer, the degree of fiber alignment is important, as an increase in aligned fibers perpendicular to the tumor boundary has been correlated to poorer patient prognosis1. Aligned collagen matrices result in increased dissemination of tumor cells via persistent migration2,3. The following is a simple protocol for embedding cells within a 3-dimensional, fibrillar collagen hydrogel. This protocol is readily adaptable to many platforms, and can reproducibly generate both aligned and random collagen matrices for investigation of cell migration, cell division, and other cellular processes in a tunable, 3-dimensional, physiological microenvironment.

Preparation of 3D Collagen Gels and Microchannels for the Study of 3D Interactions In Vivo

Collagen is a core component of the ECM, and provides essential cues for several cellular processes ranging from migration to differentiation and proliferation. Provided here is a protocol for embedding cells within 3D collagen hydrogels, and a more advanced technique for generating randomized or aligned collagen matrices using PDMS microchannels.

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

Micropatterning and Assembly of 3D Microvessels

In vitro platforms to study endothelial cells and vascular biology are largely limited to 2D endothelial cell culture, flow chambers with polymer or glass based substrates, and hydrogel-based tube formation assays. These assays, while informative, do not recapitulate lumen geometry, proper extracellular matrix, and multi-cellular proximity, which play key roles in modulating vascular function. This manuscript describes an injection molding method to generate engineered vessels with diameters on the order of 100 &#181;m. Microvessels are fabricated by seeding endothelial cells in a microfluidic channel embedded within a native type I collagen hydrogel. By incorporating parenchymal cells within the collagen matrix prior to channel formation, specific tissue microenvironments can be modeled and studied. Additional modulations of hydrodynamic properties and media composition allow for control of complex vascular function within the desired microenvironment. This platform allows for the study of perivascular cell recruitment, blood-endothelium interactions, flow response, and tissue-microvascular interactions. Engineered microvessels offer the ability to isolate the influence from individual components of a vascular niche and precisely control its chemical, mechanical, and biological properties to study vascular biology in both health and disease.

This manuscript presents an injection molding method to engineer microvessels that recapitulate physiological properties of endothelium. The microfluidic-based process creates patent 3D vascular networks with tailorable conditions, such as flow, cellular composition, geometry, and biochemical gradients. The fabrication process and examples of potential applications are described.

In vitro platforms to study endothelial cells and vascular biology are largely limited to 2D endothelial cell culture, flow chambers with polymer or glass ...

Ligand Nano-cluster Arrays in a Supported Lipid Bilayer

Currently there is considerable interest in creating ordered arrays of adhesive protein islands in a sea of passivated surface for cell biological studies. In the past years, it has become increasingly clear that living cells respond, not only to the biochemical nature of the molecules presented to them but also to the way these molecules are presented. Creating protein micro-patterns is therefore now standard in many biology laboratories; nano-patterns are also more accessible. However, in the context of cell-cell interactions, there is a need to pattern not only proteins but also lipid bilayers. Such dual proteo-lipidic patterning has so far not been easily accessible. We offer a facile technique to create protein nano-dots supported on glass and propose a method to backfill the inter-dot space with a supported lipid bilayer (SLB). From photo-bleaching of tracer fluorescent lipids included in the SLB, we demonstrate that the bilayer exhibits considerable in-plane fluidity. Functionalizing the protein dots with fluorescent groups allows us to image them and to show that they are ordered in a regular hexagonal lattice. The typical dot size is about 800 nm and the spacing demonstrated here is 2 microns. These substrates are expected to serve as useful platforms for cell adhesion, migration and mechano-sensing studies.

We present a protocol to functionalize glass with nanometric protein patches surrounded by a fluid lipid bilayer. These substrates are compatible with advanced optical microscopy and are expected to serve as platform for cell adhesion and migration studies.

Currently there is considerable interest in creating ordered arrays of adhesive protein islands in a sea of passivated surface for cell biological ...

Tunable Hydrogels from Pulmonary Extracellular Matrix for 3D Cell Culture

Here we present a method for establishing multiple component cell culture hydrogels for in vitro lung cell culture. Beginning with healthy en bloc lung tissue from porcine, rat, or mouse, the tissue is perfused and submerged in subsequent chemical detergents to remove the cellular debris. Histological comparison of the tissue before and after processing confirms removal of over 95% of double stranded DNA and alpha galactosidase staining suggests the majority of cellular debris is removed. After decellularization, the tissue is lyophilized and then cryomilled into a powder. The matrix powder is digested for 48 hr in an acidic pepsin digestion solution and then neutralized to form the pregel solution. Gelation of the pregel solution can be induced by incubation at 37 &#176;C and can be used immediately following neutralization or stored at 4 &#176;C for up to two weeks. Coatings can be formed using the pregel solution on a non-treated plate for cell attachment. Cells can be suspended in the pregel prior to self-assembly to achieve a 3D culture, plated on the surface of a formed gel from which the cells can migrate through the scaffold, or plated on the coatings. Alterations to the strategy presented can impact gelation temperature, strength, or protein fragment sizes. Beyond hydrogel formation, the hydrogel stiffness may be increased using genipin.

This is a method to create a 3-dimensional cell culture scaffold from pulmonary extracellular matrix. Intact lung is processed into hydrogels that can support the growth of cells in three-dimensions.

Here we present a method for establishing multiple component cell culture hydrogels for in vitro lung cell culture. Beginning with healthy en bloc lung ...

A Microcontroller Operated Device for the Generation of Liquid Extracts from Conventional Cigarette Smoke and Electronic Cigarette Aerosol

Electronic cigarettes are the most popular tobacco product among middle and high schoolers and are the most popular alternative tobacco product among adults. High quality, reproducible research on the consequences of electronic cigarette use is essential for understanding emerging public health concerns and crafting evidence based regulatory policy. While a growing number of papers discuss electronic cigarettes, there is little consistency in methods across groups and very little consensus on results. Here, we describe a programmable laboratory device that can be used to create extracts of conventional cigarette smoke and electronic cigarette aerosol. This protocol details instructions for the assembly and operation of said device, and demonstrates the use of the generated extract in two sample applications: an in vitro cell viability assay and gas-chromatography mass-spectrometry. This method provides a tool for making direct comparisons between conventional cigarettes and electronic cigarettes, and is an accessible entry point into electronic cigarette research.

Here, we describe a programmable laboratory device that can be used to create extracts of conventional cigarette smoke and electronic cigarette aerosol. This method provides a useful tool for making direct comparisons between conventional cigarettes and electronic cigarettes, and is an accessible entry point into electronic cigarette research.

Electronic cigarettes are the most popular tobacco product among middle and high schoolers and are the most popular alternative tobacco product among ...

A Human 3D Extracellular Matrix-Adipocyte Culture Model for Studying Matrix-Cell Metabolic Crosstalk

The extracellular matrix (ECM) plays a central role in regulating tissue homeostasis, engaging in crosstalk with cells and regulating multiple aspects of cellular function. The ECM plays a particularly important role in adipose tissue function in obesity, and alterations in adipose tissue ECM deposition and composition are associated with metabolic disease in mice and humans. Tractable in vitro models that permit dissection of the roles of the ECM and cells in contributing to global tissue phenotype are sparse. We describe a novel 3D in vitro model of human ECM-adipocyte culture that permits study of the specific roles of the ECM and adipocytes in regulating adipose tissue metabolic phenotype. Human adipose tissue is decellularized to isolate ECM, which is subsequently repopulated with preadipocytes that are then differentiated within the ECM into mature adipocytes. This method creates ECM-adipocyte constructs that are metabolically active and retain characteristics of the tissues and patients from which they are derived. We have used this system to demonstrate disease-specific ECM-adipocyte crosstalk in human adipose tissue. This culture model provides a tool for dissecting the roles of the ECM and adipocytes in contributing to global adipose tissue metabolic phenotype and permits study of the role of the ECM in regulating adipose tissue homeostasis.

We describe a 3D human extracellular matrix-adipocyte in vitro culture system that permits dissection of the roles of the matrix and adipocytes in contributing to adipose tissue metabolic phenotype.

The extracellular matrix (ECM) plays a central role in regulating tissue homeostasis, engaging in crosstalk with cells and regulating multiple aspects of ...

Generation of Dynamical Environmental Conditions using a High-Throughput Microfluidic Device

Mimicking in vivo environmental conditions is crucial for in vitro studies on complex life machinery. However, current techniques targeting live cells and organs are either highly expensive, like robotics, or lack nanoliter volume and millisecond time accuracy in liquid manipulation. We herein present the design and fabrication of a microfluidic system, which consists of 1,500 culture units, an array of enhanced peristaltic pumps and an on-site mixing modulus. To demonstrate the capacities of the microfluidic device, neural stem cell (NSC) spheres are maintained in the proposed system. We observed that when the NSC sphere is exposed to CXCL in day 1 and EGF in day 2, the round-shaped conformation is well maintained. Variation in the input order of 6 drugs causes morphological changes to the NSC sphere and the expression level representative marker for NSC stemness (i.e., Hes5 and Dcx). These results indicate that dynamic and complex environmental conditions have great effects on NSC differentiation and self-renewal, and the proposed microfluidic device is a suitable platform for high throughput studies on the complex life machinery.

We present a microfluidic system for high throughput studies on complex life machinery, which consists of 1500 culture units, an array of enhanced peristaltic pumps and an on-site mixing modulus. The microfluidic chip allows for the analysis of the highly complex and dynamic micro-environmental conditions in vivo.

Mimicking in vivo environmental conditions is crucial for in vitro studies on complex life machinery. However, current techniques targeting live cells and ...