Name: segmenting growth of endothelial cells in 6-well plates on an orbital shaker for mechanobiological studies
Uploaded: 2021-06-03T12:30:00
Description: Watch this Scientific Journal Video about Segmenting Growth of Endothelial Cells in 6-Well Plates on an Orbital Shaker for Mechanobiological Studies at JoVE.com

The authors gratefully acknowledge a British Heart Foundation project grant (to PDW), a National Medical Research Council Singapore TAAP and DYNAMO Grant (to XW, NMRC/OFLCG/004/2018, NMRC/OFLCG/001/2017), an A*STAR Graduate Scholarship (to KTP), and a British Heart Foundation Center of Research Excellence studentship (to MA).

1. Fabrication of devices and preparation of reagents
<ol>
	<li>Fabrication of stainless-steel module
	<ol>
		<li>Fabricate the stainless-steel module from a grade 316 stainless-steel using a CNC milling machine according to the engineering drawing provided (Figure 1).</li>
	</ol>
	</li>
	<li>3D printing of a polydimethylsiloxane (PDMS) mold
	<ol>
		<li>Prepare a 3D computer aided design (CAD) model of the PDMS mold using SolidWorks according to the engineering drawing provided (<strong cl...

<ol>
	<li>Hahn, C., Schwartz, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanotransduction+in+vascular+physiology+and+atherogenesis.">Mechanotransduction in vascular physiology and atherogenesis.</a> Nature Reviews Molecular Cell Biology. 10 (1), 53-62 (2009).</li><li>Wang, C., Baker, B. M., Chen, C. S., Schwartz, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endothelial+Cell+Sensing+of+Flow+Direction.">Endothelial Cell Sensing of Flow Direction.</a> Arteriosclerosis, Thrombosis, and Vascular Biology. 33 (9), 2130-2136 (2013).</li><li>Tzima, E., 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=A+mechanosensory+complex+that+mediates+the+endothelial+cell+response+to+fluid+shear+stress.">A mechanosensory complex that mediates the endothelial cell response to fluid shear stress.</a> Nature. 437, 426-431 (2005).</li><li>Potter, C. M. F., Schobesberger, S., Lundberg, M. H., Weinberg, P. D., Mitchell, J. A., Gorelik, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Shape+and+compliance+of+endothelial+cells+after+shear+stress+in+vitro+or+from+different+aortic+regions:+Scanning+ion+conductance+microscopy+study.">Shape and compliance of endothelial cells after shear stress in vitro or from different aortic regions: Scanning ion conductance microscopy study.</a> PLoS ONE. 7 (2), 1-5 (2012).</li><li>Asakura, T., Karino, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Flow+Patterns+and+Spatial+Distribution+of+Atherosclerotic+Lesions+in+Human.">Flow Patterns and Spatial Distribution of Atherosclerotic Lesions in Human.</a> Circulation Research. 66 (4), 1045-1067 (1990).</li><li>Bond, A. R., Iftikhar, S., Bharath, A. A., Weinberg, P. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Morphological+evidence+for+a+change+in+the+pattern+of+aortic+wall+shear+stress+with+age.">Morphological evidence for a change in the pattern of aortic wall shear stress with age.</a> Arteriosclerosis, Thrombosis, and Vascular Biology. 31 (3), 543-550 (2011).</li><li>Giddens, D. P., Zarins, C. K., Glagov, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+fluid+mechanics+in+the+localization+and+detection+of+atherosclerosis.">The role of fluid mechanics in the localization and detection of atherosclerosis.</a> Journal of biomechanical engineering. 115, 588-594 (1993).</li><li>Schnittler, H. J., Franke, R. P., Akbay, U., Mrowietz, C., Drenckhahn, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improved+in+vitro+rheological+system+for+studying+the+effect+of+fluid+shear+stress+on+cultured+cells.">Improved in vitro rheological system for studying the effect of fluid shear stress on cultured cells.</a> The American journal of physiology. 265, 289-298 (1993).</li><li>Levesque, M. J., Nerem, R. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+elongation+and+orientation+of+cultured+endothelial+cells+in+response+to+shear+stress.">The elongation and orientation of cultured endothelial cells in response to shear stress.</a> Journal of biomechanical engineering. 107 (4), 341-347 (1985).</li><li>Chiu, 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=Analysis+of+the+effect+of+disturbed+flow+on+monocytic+adhesion+to+endothelial+cells.">Analysis of the effect of disturbed flow on monocytic adhesion to endothelial cells.</a> Journal of Biomechanics. 36 (12), 1883-1895 (2003).</li><li>Venugopal Menon, N., 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=A+tunable+microfluidic+3D+stenosis+model+to+study+leukocyte-endothelial+interactions+in+atherosclerosis.">A tunable microfluidic 3D stenosis model to study leukocyte-endothelial interactions in atherosclerosis.</a> APL Bioengineering. 2 (1), 016103 (2018).</li><li>Warboys, C. M., Ghim, M., Weinberg, P. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Understanding+mechanobiology+in+cultured+endothelium:+A+review+of+the+orbital+shaker+method.">Understanding mechanobiology in cultured endothelium: A review of the orbital shaker method.</a> Atherosclerosis. 285, 170-177 (2019).</li><li>Ghim, M., Pang, K. T., Arshad, M., Wang, X., Weinberg, P. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+method+for+segmenting+growth+of+cells+in+sheared+endothelial+culture+reveals+the+secretion+of+an+anti-inflammatory+mediator.">A novel method for segmenting growth of cells in sheared endothelial culture reveals the secretion of an anti-inflammatory mediator.</a> Journal of Biological Engineering. 12 (1), 15 (2018).</li><li>Sage, H., Pritzl, P., Bornstein, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Secretory+phenotypes+of+endothelial+cells+in+culture:+comparison+of+aortic,+venous,+capillary,+and+corneal+endothelium.">Secretory phenotypes of endothelial cells in culture: comparison of aortic, venous, capillary, and corneal endothelium.</a> Arteriosclerosis. 1 (6), 427-442 (1981).</li><li>Tunica, D. G., 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=Proteomic+analysis+of+the+secretome+of+human+umbilical+vein+endothelial+cells+using+a+combination+of+free-flow+electrophoresis+and+nanoflow+LC-MS/MS.">Proteomic analysis of the secretome of human umbilical vein endothelial cells using a combination of free-flow electrophoresis and nanoflow LC-MS/MS.</a> Proteomics. 9, 4991-4996 (2009).</li><li>Griffoni, C., 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=Modification+of+proteins+secreted+by+endothelial+cells+during+modeled+low+gravity+exposure.">Modification of proteins secreted by endothelial cells during modeled low gravity exposure.</a> Journal of Cellular Biochemistry. 112, 265-272 (2011).</li><li>Ghim, M., 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=Visualization+of+three+pathways+for+macromolecule+transport+across+cultured+endothelium+and+their+modification+by+flow.">Visualization of three pathways for macromolecule transport across cultured endothelium and their modification by flow.</a> American Journal of Physiology-Heart and Circulatory Physiology. 313 (5), 959-973 (2017).</li><li>Levesque, M. J., Liepsch, D., Moravec, S., Nerem, R. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Correlation+of+endothelial+cell+shape+and+wall+shear+stress+in+a+stenosed+dog+aorta.">Correlation of endothelial cell shape and wall shear stress in a stenosed dog aorta.</a> Arteriosclerosis: An Official Journal of the American Heart Association, Inc. 6 (2), 220-229 (1986).</li></ol>

The swirling-well method is capable of generating complex flow profiles in a single well - Low Magnitude Multidirectional Flow (LMMF) in the center and High Magnitude Uniaxial Flow (HMUF) at the edge of the well. However, shear stress-mediated secretions of soluble mediator will be mixed in the swirling medium and affect cells in the whole well, potentially masking the true effect of a particular shear stress profile on the cells.
The coating method demonstrated here overcomes this issue by re...

Responses of vascular cells to their mechanical environment are important in the normal function of blood vessels and in the development of disease1. The mechanobiology of the endothelial cells (ECs) that line the interior surface of all blood vessels has been a particular focus of mechanobiological research because ECs directly experience the shear stress generated by blood flow over them. Various phenotypic changes such as inflammatory responses, altered stiffness and morphology, the release of vasoactive substances, and the localization and expression of junctional proteins depend on EC exposure to shear stress2,3,4. Shear-dependent endothelial properties may also account for the patchy development of diseases such as atherosclerosis5,6,7.
It is useful to study the effect of shear on ECs in culture, where stresses can be controlled, and ECs can be isolated from other cell types. Commonly used in vitro devices for applying shear stress to ECs include the parallel-plate flow chamber and the cone-and-plate viscometer, but only uniaxial steady, oscillatory, and pulsatile flow can be applied8,9. Although modified flow chambers with tapered or branching geometries and microfluidic chips that mimic a stenotic geometry have been developed, their low-throughput and the relatively short culture duration that is possible pose a challenge10, 11.
The orbital shaker (or swirling well) method for the study of endothelial mechanotransduction, in which cells are grown in standard cell culture plasticware placed on the platform of an orbital shaker, is gaining increasing attention because it is capable of chronically imposing complex, spatially varying shear stress patterns on ECs with high throughput (see review by Warboys et al.12). Computational Fluid Dynamics (CFD) simulations have been employed to characterize the spatial and temporal variation of shear stress in a swirling well. The swirling motion of culture medium caused by the orbital motion of the shaker platform on which the plate is placed leads to Low Magnitude Multidirectional Flow (LMMF, or putatively pro-atherogenic flow) at the center and High Magnitude Uniaxial Flow (HMUF, or putatively atheroprotective flow) at the edge of the wells of a 6-well plate. For example, time-averaged wall shear stress (TAWSS) is approximately 0.3 Pa at the center and 0.7 Pa at the edge of a 6-well plate swirled at 150 rpm with a 5 mm orbital radius13. The method requires only commercially available plasticware and the orbital shaker itself.
There is, however, a drawback to the method (and to other methods of imposing flows in vitro): ECs release soluble mediators and microparticles in a shear-dependent manner14,15,16 and this secretome may affect ECs in regions of the well other than the one in which they were released, due to the mixing in the swirling medium. This may mask the actual effects of shear stress on EC phenotype. For example, Ghim et al. have speculated that this accounts for the apparently identical influence of different shear profiles on transcellular transport of large particles17.
Here we describe a method for promoting human umbilical vein endothelial cell (HUVEC) adhesion in specific regions of a 6-well plate using fibronectin coating while using Pluronic F-127 to passivate the surface and prevent growth elsewhere. The method resolves the limitation described above because, by segmenting cell growth, ECs experience only one kind of shear profile, and are not influenced by secretomes from ECs exposed to other profiles elsewhere in the well.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Cell and Media</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Endothelial Growth Medium (EGM-2)</td>
			<td>Lonza</td>
			<td>cc-3162</td>
			<td></td>
		</tr>
		<tr>
			<td>Human Umbilical Vein Endothelial Cells</td>
			<td>NA</td>
			<td>NA</td>
			<td>Isolated from cords obtained from donors with uncomplicated labour at the Hammersmith Hospital</td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Reagents and Materials</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Alexa Fuor 488-labelled goat anti-rabbit IgG</td>
			<td>Thermofisher Scientific</td>
			<td>A11008</td>
			<td></td>
		</tr>
		<tr>
			<td>Bovine Serum Albumin</td>
			<td>Sigma-Aldrich</td>
			<td>A9418-50G</td>
			<td></td>
		</tr>
		<tr>
			<td>Falcon 6 Well Clear Flat Bottom Not Treated&#160;</td>
			<td>Scientific Laboratory Supplies Ltd&#160;</td>
			<td>351146</td>
			<td></td>
		</tr>
		<tr>
			<td>Fibronectin from Bovine Plasma</td>
			<td>Sigma-Aldrich</td>
			<td>F1141-5MG</td>
			<td></td>
		</tr>
		<tr>
			<td>Paraformaldehyde</td>
			<td>Sigma-Aldrich</td>
			<td>158127-500G</td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphate-Buffered Saline</td>
			<td>Sigma-Aldrich</td>
			<td>D8537-6X500ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Pluronic F-127</td>
			<td>Sigma-Aldrich</td>
			<td>P2443</td>
			<td></td>
		</tr>
		<tr>
			<td>Recombinant Human TNF-a</td>
			<td>Peprotech</td>
			<td>300-01A</td>
			<td></td>
		</tr>
		<tr>
			<td>RS PRO 2.85 mm Black PLA 3D Printer Filament, 1 kg</td>
			<td>RS</td>
			<td>832-0264</td>
			<td></td>
		</tr>
		<tr>
			<td>Stainless Steel 316</td>
			<td>Metal Supermarket</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr>
			<td>Sylgard184 Silicone Elastomer kit</td>
			<td>Farnell</td>
			<td>101697</td>
			<td></td>
		</tr>
		<tr>
			<td>Triton X-100</td>
			<td>Sigma-Aldrich</td>
			<td>X100-100ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Trypsin-EDTA solution</td>
			<td>Sigma-Aldrich</td>
			<td>T4049-100ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Zonula Occludens-1 (ZO-1) antibody</td>
			<td>Cell Signaling Technology</td>
			<td>13663</td>
			<td></td>
		</tr>
		<tr>
			<td>DRAQ5 (5mM)</td>
			<td>Bio Status</td>
			<td>DR50200</td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Equipments</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Grant Orbital Shaker PSU-10i</td>
			<td>Scientific Laboratory Supplies Ltd&#160;</td>
			<td>SHA7930</td>
			<td></td>
		</tr>
		<tr>
			<td>Leica TCS SP5 Confocal Microscope</td>
			<td>Leica</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr>
			<td>Retaining Ring Pliers</td>
			<td>Misumi</td>
			<td>RTWP32-58</td>
			<td></td>
		</tr>
		<tr>
			<td>Retaining Rings/Internal/C-Type</td>
			<td>Misumi</td>
			<td>RTWS35</td>
			<td></td>
		</tr>
		<tr>
			<td>Ultimaker 2+3-D printer</td>
			<td>Ultimaker</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Softwares</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Cura 2.6.2</td>
			<td>Ultimaker</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr>
			<td>MATLAB</td>
			<td>The MathWorks</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr>
			<td>Solidworks 2016</td>
			<td>Dassault Systemes</td>
			<td>NA</td>
			<td></td>
		</tr>
	</tbody>
</table>

segmenting growth of endothelial cells in 6-well plates on an orbital shaker for mechanobiological studies

Shear stress imposed on the arterial wall by the flow of blood affects endothelial cell morphology and function. Low magnitude, oscillatory and multidirectional shear stresses have all been postulated to stimulate a pro-atherosclerotic phenotype in endothelial cells, whereas high magnitude and unidirectional or uniaxial shear are thought to promote endothelial homeostasis. These hypotheses require further investigation, but traditional in vitro techniques have limitations, and are particularly poor at imposing multidirectional shear stresses on cells. 
One method that is gaining increasing use is to culture endothelial cells in standard multi-well plates on the platform of an orbital shaker; in this simple, low-cost, high-throughput and chronic method, the swirling medium produces different patterns and magnitudes of shear, including multidirectional shear, in different parts of the well. However, it has a significant limitation: cells in one region, exposed to one type of flow, may release mediators into the medium that affect cells in other parts of the well, exposed to different flows, hence distorting the apparent relation between flow and phenotype. 
Here we present an easy and affordable modification of the method that allows cells to be exposed only to specific shear stress characteristics. Cell seeding is restricted to a defined region of the well by coating the region of interest with fibronectin, followed by passivation using passivating solution. Subsequently, the plates can be swirled on the shaker, resulting in exposure of cells to well-defined shear profiles such as low magnitude multidirectional shear or high magnitude uniaxial shear, depending on their location. As before, the use of standard cell-culture plasticware allows straightforward further analysis of the cells. The modification has already allowed the demonstration of soluble mediators, released from endothelium under defined shear stress characteristics, that affect cells located elsewhere in the well.

Adhesion of HUVECs to regions of the well plate not coated with fibronectin was abrogated by Pluronic F-127 passivation; growth was confined to the region coated with fibronectin even after 72 h of culture, with and without shear stress application (Figure 4A, Figure 4C). Without the Pluronic F-127 passivation, HUVECs attached to the surface without fibronectin and had proliferated further by 72 h of culture (<strong class="xfig"...

Watch this Scientific Journal Video about Segmenting Growth of Endothelial Cells in 6-Well Plates on an Orbital Shaker for Mechanobiological Studies at JoVE.com

Segmenting Growth of Endothelial Cells in 6-Well Plates on an Orbital Shaker for Mechanobiological Studies

This protocol describes a coating method to restrict endothelial cell growth to a specific region of a 6-well plate for shear stress application using the orbital shaker model.

Shear stress imposed on the arterial wall by the flow of blood affects endothelial cell morphology and function. Low magnitude, oscillatory and ...

This protocol describes a coating method to restrict endothelial cell growth to a specific region of a 6-well plate for sheer stress application using the orbital shaker model. A common way to study effects of flow on endothelium is to culture endothelial cells in multi-well culture plates on an orbital shaker. The orbital shaker induces a wave that rotates around the well.Cells at the center of the well experience the kind of flows that are thought to lead to atherosclerosis. Cells closer to the edge experience flow that is thought to be protective. Properties of the cells in each region are assumed to depend on the sheer stresses that they experience.However, there is a potential floor in this logic. Endothelial cells release mediators in a flow-dependent fashion. These mediators will reach a uniform concentration in the swirling medium and will therefore affect cells in regions other than the one where they were released.That may corrupt or hide true effects of shear on cell behavior. The effect is not limited to the swirling well system. It may occur even in simple models, like the parallel plate flow chamber.It can be avoided by growing cells in only one part of the system. Here, we describe methods for permitting cell adhesion only in the center or only at the edge of the swirling well. Fabrication of stainless steel module.Fabricate the stainless steel module from a grade 316 stainless steel according to an engineering drawing provided. 3D printing on PDMs. Prepare a 3D CAD model of PDMs mold using SOLIDWORKS according to the engineering drawing provided.Export the CAD model to an STL file and import the STL file into Cura 2.6.2. Slice the model into layers with a print speed of 50 millimeters per second and infill density of 60%Export the file as a GCode. Uploaded it to an Ultimaker 3D printer for printing.Use polylactic acid as the printing material. Casting of PDMS ring. Mix the PDMS base and curing agent well with the ratio of 90.9%base and 9.1%curing agent.Pour the well-mixed solution into the 3D-printed mold. Remove bubbles in a vacuum degassing chamber. Cure it for one hour in an 80-degrees furnace.Allow the PDMS ring to cool to room temperature. Then remove the cured PDMS ring carefully from the mold. Preparation of 1%Pluronic F-127.Weigh out five grams of Pluronic F-127. Pour it into a glass bottle. Then add a hundred mil of Milli-Q water into the glass bottle.This gives a 5%Pluronic F-127 solution. Ensure that all Pluronic F-127 powder is submerged in the water. Close the cap and autoclave it using a liquid sterilization cycle program.Let the solution cool to room temperature before use. Add 10 mil of 5%Pluronic F-127 solution to 40 mil of autoclaved Milli-Q water to make 1%Pluronic F-127 solution. Perform the dilution in a biosafety cabinet hood.Store both 1%and 5%Pluronic F-127 at room temperature. Coating of 6-well plate. Autoclave stainless steel module, PDMS ring, and tweezers before use.Perform all subsequent procedures in a BSC hood and observe aseptic techniques to ensure sterility. Place the PDMS ring in a 6-well using tweezers. Use the external rim of the PDMS ring to align the PDMS ring concentrically within the well.Note, only non tissue culture-treated well plates should be used. Place the stainless steel module on top of the PDMS ring using tweezers. Insert the tips of the internal retaining ring pliers into the grip holds of the retaining ring.Squeeze the holder to reduce the diameter of the retaining ring. Put it into the 6-well, press it firmly on the stainless steel module, and release the pliers to secure the PDMS ring in the well. Add one mil of five microgram per microliter fibronectin into the center or the edge of the well, depending on the region of interest, through the opening of PDMS ring and stainless steel module.Swirl the plate to ensure the fibronectin solution covers all the region of interest. Incubate for 30 minutes at 37 degrees in a humidified incubator under 95%air and 5%CO2. Remove the fibronectin solution from the well.And now wash twice with PBS. Once done, completely remove the PBS from the well. Remove the retaining ring, stainless steel module, and PDMS ring from the well.Add 1.5 mil of 1%Pluronic F-127 into the well and incubate for one hour at room temperature to passivate the uncoated surface. Remove the Pluronic F-127 solution from the well and wash three times with PBS. Once washed, use the coated well immediately or store at four degrees for up to two weeks with the layer of PBS in the coated well.Seeding of endothelial cells. Count cells using a hemocytometer and seed 180, 000 cells into a coated 6-well plate in 1.5 mil of pre-warm cell culture medium. Shake the well plate laterally to ensure that the cells distribute evenly in the well.Leave it in a 37-degrees humidified incubator under 95%air and 5%CO2 overnight. Shear stress application using an orbital shaker. Cells should reach confluence after three days of growth.Replace the medium with 1.9 mil of pre-warn cell culture medium to achieve a height of two millimeters. Place a well plate on the platform of an orbital shaker in a humidified incubator and swirl it at 150 RPM for three days. Optional, after two days of shear, cytokines can be added to the cell culture medium to investigate the interplay between cytokines and sheer stress.After treatment, shear the cells for another day. In this study, TNF-alpha was used to activate the cells. Perform analysis after three days of shear stress application.Microscope images show that Pluronic F-127 prevented HUVEC adhesion to the region without fibronectin coating. No HUVECs were attached to the part of the well surface that had not been pretreated with fibronectin prior to passivation of Pluronic F-127 after 24 hours, in figure A, and 72 hours, in figure C, of growth. Without Pluronic F-127 passivation, HUVECs were attached to the surface without fibronectin, 24 hours after seeding, in figure B, and are proliferated further by 72 hours, in figure D.The scale bar is equal to 500 micrometers.Nuclear Red stain shows the morphology of sheared HUVECs, A, in the center, and B, at the edge of a full well. Scale bar is equal to a hundred micrometers. A and B also show cell outlines delineated by immunostaining of ZO-1.Note the alignment and elongation of cells at the edge but not at the center. It shows no significant difference in nuclear shape index, indicating roundness, between HUVECs grown in full well and segmented wells were seen for untreated or TNF-alpha-treated HUVECs. Cells were more elongated near the edge of the well.A tendency for a greater elongation in TNF-alpha-treated HUVECs was not consistently significant across locations. No significant difference was observed between full and segmented wells in density number of A, untreated, and B, TNF-alpha-treated HUVECs at different radial locations. In both cases, there were more cells per unit area at the edge than at the center of the well.In conclusion, the method we have outlined here allows you to grow cells in just one region of the swirling well or indeed, of any plastic-based cell culture system. That means cells in one part of the well experiencing one type of flow are not influenced by mediators released from cells in another region experiencing different flows. Not only that, we can look at cells grown in one region with or without cells being grown in other regions.That allows the effects of such soluble mediators to be demonstrated. Testing the effects of conditioned medium on naive cells permits the same thing. By analyzing condition medium, the mediators can be identified.

segmenting-growth-endothelial-cells-6-well-plates-on-an-orbital

Research

JoVE Journal

Bioengineering

On-Chip Endothelial Inflammatory Phenotyping

Atherogenesis is potentiated by metabolic abnormalities that contribute to a heightened state of systemic inflammation resulting in endothelial dysfunction. However, early functional changes in endothelium that signify an individual's level of risk are not directly assessed clinically to help guide therapeutic strategy. Moreover, the regulation of inflammation by local hemodynamics contributes to the non-random spatial distribution of atherosclerosis, but the mechanisms are difficult to delineate in vivo. We describe a lab-on-a-chip based approach to quantitatively assay metabolic perturbation of inflammatory events in human endothelial cells (EC) and monocytes under precise flow conditions. Standard methods of soft lithography are used to microfabricate vascular mimetic microfluidic chambers (VMMC), which are bound directly to cultured EC monolayers.1 These devices have the advantage of using small volumes of reagents while providing a platform for directly imaging the inflammatory events at the membrane of EC exposed to a well-defined shear field. We have successfully applied these devices to investigate cytokine-,2 lipid-3, 4 and RAGE-induced5 inflammation in human aortic EC (HAEC). Here we document the use of the VMMC to assay monocytic cell (THP-1) rolling and arrest on HAEC monolayers that are conditioned under differential shear characteristics and activated by the inflammatory cytokine TNF-&alpha;. Studies such as these are providing mechanistic insight into atherosusceptibility under metabolic risk factors.

Microfluidic flow chambers etched by photolithography and fabricated from PDMS are applied to probe functional outcomes associated with EC dysfunction and inflammation. In a representative experiment, the ability of differential shear stress to modulate monocytic cell adhesion to cytokine activated EC monolayers is demonstrated.

Atherogenesis is potentiated by metabolic abnormalities that contribute to a heightened state of systemic inflammation resulting in endothelial ...

Time-lapse Fluorescence Imaging of Arabidopsis Root Growth with Rapid Manipulation of The Root Environment Using The RootChip

The root functions as the physical anchor of the plant and is the organ responsible for uptake of water and mineral nutrients such as nitrogen, phosphorus, sulfate and trace elements that plants acquire from the soil. If we want to develop sustainable approaches to producing high crop yield, we need to better understand how the root develops, takes up a wide spectrum of nutrients, and interacts with symbiotic and pathogenic organisms. To accomplish these goals, we need to be able to explore roots in microscopic detail over time periods ranging from minutes to days.
We developed the RootChip, a polydimethylsiloxane (PDMS)- based microfluidic device, which allows us to grow and image roots from Arabidopsis seedlings while avoiding any physical stress to roots during preparation for imaging1 (Figure 1). The device contains a bifurcated channel structure featuring micromechanical valves to guide the fluid flow from solution inlets to each of the eight observation chambers2. This perfusion system allows the root microenvironment to be controlled and modified with precision and speed. The volume of the chambers is approximately 400 nl, thus requiring only minimal amounts of test solution.
Here we provide a detailed protocol for studying root biology on the RootChip using imaging-based approaches with real time resolution. Roots can be analyzed over several days using time lapse microscopy. Roots can be perfused with nutrient solutions or inhibitors, and up to eight seedlings can be analyzed in parallel. This system has the potential for a wide range of applications, including analysis of root growth in the presence or absence of chemicals, fluorescence-based analysis of gene expression, and the analysis of biosensors, e.g. FRET nanosensors3.

This article provides a protocol for cultivation of Arabidopsis seedlings in the RootChip, a microfluidic imaging platform that combines automated control of growth conditions with microscopic root monitoring and FRET-based measurement of intracellular metabolite levels.

The root functions as the physical anchor of the plant and is the organ responsible for uptake of water and mineral nutrients such as nitrogen, ...

A Novel Three-dimensional Flow Chamber Device to Study Chemokine-directed Extravasation of Cells Circulating under Physiological Flow Conditions

Extravasation of circulating cells from the bloodstream plays a central role in many physiological and pathophysiological processes, including stem cell homing and tumor metastasis. The three-dimensional flow chamber device (hereafter the 3D device) is a novel in vitro technology that recreates physiological shear stress and allows each step of the cell extravasation cascade to be quantified. The 3D device consists of an upper compartment in which the cells of interest circulate under shear stress, and a lower compartment of static wells that contain the chemoattractants of interest. The two compartments are separated by porous inserts coated with a monolayer of endothelial cells (EC). An optional second insert with microenvironmental cells of interest can be placed immediately beneath the EC layer. A gas exchange unit allows the optimal CO2 tension to be maintained and provides an access point to add or withdraw cells or compounds during the experiment. The test cells circulate in the upper compartment at the desired shear stress (flow rate) controlled by a peristaltic pump. At the end of the experiment, the circulating and migrated cells are collected for further analyses. The 3D device can be used to examine cell rolling on and adhesion to EC under shear stress, transmigration in response to chemokine gradients, resistance to shear stress, cluster formation, and cell survival. In addition, the optional second insert allows the effects of crosstalk between EC and microenvironmental cells to be examined. The translational applications of the 3D device include testing of drug candidates that target cell migration and predicting the in vivo behavior of cells after intravenous injection. Thus, the novel 3D device is a versatile and inexpensive tool to study the molecular mechanisms that mediate cellular extravasation.

The three-dimensional flow chamber device is a novel in vitro technology for the quantitative and step-wise evaluation of the extravasation cascade of cells circulating under conditions of physiological shear stress. The device therefore fills a critical need for basic, preclinical, and clinical studies of cell migration.

Extravasation of circulating cells from the bloodstream plays a central role in many physiological and pathophysiological processes, including stem cell ...

3D Orbital Tracking in a Modified Two-photon Microscope: An Application to the Tracking of Intracellular Vesicles

The objective of this video protocol is to discuss how to perform and analyze a three-dimensional fluorescent orbital particle tracking experiment using a modified two-photon microscope1. As opposed to conventional approaches (raster scan or wide field based on a stack of frames), the 3D orbital tracking allows to localize and follow with a high spatial (10 nm accuracy) and temporal resolution (50 Hz frequency response) the 3D displacement of a moving fluorescent particle on length-scales of hundreds of microns2. The method is based on a feedback algorithm that controls the hardware of a two-photon laser scanning microscope in order to perform a circular orbit around the object to be tracked: the feedback mechanism will maintain the fluorescent object in the center by controlling the displacement of the scanning beam3-5. To demonstrate the advantages of this technique, we followed a fast moving organelle, the lysosome, within a living cell6,7. Cells were plated according to standard protocols, and stained using a commercially lysosome dye. We discuss briefly the hardware configuration and in more detail the control software, to perform a 3D orbital tracking experiment inside living cells. We discuss in detail the parameters required in order to control the scanning microscope and enable the motion of the beam in a closed orbit around the particle. We conclude by demonstrating how this method can be effectively used to track the fast motion of a labeled lysosome along microtubules in 3D within a live cell. Lysosomes can move with speeds in the range of 0.4-0.5 &#181;m/sec, typically displaying a directed motion along the microtubule network8.

In this video protocol we track - at high speed and in three dimensions - fluorescently labeled lysosomes within living cells, using the orbital tracking method in a modified two-photon microscope.

The objective of this video protocol is to discuss how to perform and analyze a three-dimensional fluorescent orbital particle tracking experiment using a ...

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.

To improve the therapeutic effectiveness of cell transplantation, a transplantation system of genetically modified, injectable spheroids was developed. ...

Studying the Stoichiometry of Epidermal Growth Factor Receptor in Intact Cells using Correlative Microscopy

This protocol describes the labeling of epidermal growth factor receptor (EGFR) on COS7 fibroblast cells, and subsequent correlative fluorescence microscopy and environmental scanning electron microscopy (ESEM) of whole cells in hydrated state. Fluorescent quantum dots (QDs) were coupled to EGFR via a two-step labeling protocol, providing an efficient and specific protein labeling, while avoiding label-induced clustering of the receptor. Fluorescence microscopy provided overview images of the cellular locations of the EGFR. The scanning transmission electron microscopy (STEM) detector was used to detect the QD labels with nanoscale resolution. The resulting correlative images provide data of the cellular EGFR distribution, and the stoichiometry at the single molecular level in the natural context of the hydrated intact cell. ESEM-STEM images revealed the receptor to be present as monomer, as homodimer, and in small clusters. Labeling with two different QDs, i.e.,&#160;one emitting at 655 nm and at 800 revealed similar characteristic results.

This protocol describes the labeling of epidermal growth factor receptor (EGFR) on COS7 fibroblast cells, and subsequent correlative light- and electron microscopy of whole cells in hydrated state. The label contained fluorescent quantum dots. The protocol can be used to study the stoichiometry of EGFR at the single molecule level.

This protocol describes the labeling of epidermal growth factor receptor (EGFR) on COS7 fibroblast cells, and subsequent correlative fluorescence ...

Electrotaxis Studies of Lung Cancer Cells using a Multichannel Dual-electric-field Microfluidic Chip

The behavior of directional cell migration under a direct current electric-field (dcEF) is referred to as electrotaxis. The significant role of physiological dcEF in guiding cell movement during embryo development, cell differentiation, and wound healing has been demonstrated in many studies. By applying microfluidic chips to an electrotaxis assay, the investigation process is shortened and experimental errors are minimized. In recent years, microfluidic devices made of polymeric substances (e.g., polymethylmethacrylate, PMMA, or acrylic) or polydimethylsiloxane (PDMS) have been widely used in studying the responses of cells to electrical stimulation. However, unlike the numerous steps required to fabricate a PDMS device, the simple and rapid construction of the acrylic micro&#64258;uidic chip makes it suitable for both device prototyping and production. Yet none of the reported devices facilitate the efficient study of the simultaneous chemical and dcEF effects on cells. In this report, we describe our design and fabrication of an acrylic-based multichannel dual-electric-field (MDF) chip to investigate the concurrent effect of chemical and electrical stimulation on lung cancer cells. The MDF chip provides eight combinations of electrical/chemical stimulations in a single test. The chip not only greatly shortens the required experimental time but also increases accuracy in electrotaxis studies.

Many microfluidic devices have been developed for use in the study of electrotaxis. Yet, none of these chips allows the efficient study of the simultaneous chemical and electric-field (EF) effects on cells. We developed a polymethylmethacrylate-based device that offers better-controlled coexisting EF and chemical stimulation for use in electrotaxis research.

The behavior of directional cell migration under a direct current electric-field (dcEF) is referred to as electrotaxis. The significant role of ...

An Orbital Shaking Culture of Mammalian Cells in O-shaped Vessels to Produce Uniform Aggregates

Suspension cultures of mammalian cell aggregates are required for various applications in medical and biotechnological fields. The disposable bag-based method is one of the simplest techniques for the mass production of cellular aggregates, but it does not protect the cultures against over-aggregation, which occurs when they gather at the bottom center of the culture vessel. To solve this problem, we developed an O-shaped dish and an O-shaped bag, neither of which contains a central region. Aggregates grown in either O-shaped culture vessel were noticeably more uniform in size than aggregates grown in conventional vessels. Histological analyses showed that aggregates in conventional culture dishes contained necrotic cores most likely caused by a poor oxygen supply. In contrast, aggregates that were grown in the O-shaped bag, even those with similar diameters to aggregates in conventional culture dishes, did not show necrotic cores. These results suggest that the O-shaped bag provides sufficient oxygen to the aggregates due to the oxygen permeability of the bag material. We, therefore, propose that this novel gas-permeable O-shaped culture bag is suitable for the mass production of uniform aggregates that are necessary in various biotechnological fields.

Here we present a protocol for using O-shaped vessels, specialized for suspension cultures of cellular aggregates, with orbital shaking. The HEK293 cells grown in this bag form more homogeneous aggregates than those grown in conventional culture vessels.

Suspension cultures of mammalian cell aggregates are required for various applications in medical and biotechnological fields. The disposable bag-based ...

A Novel Surgical Technique As a Foundation for In Vivo Partial Liver Engineering in Rat

Organ engineering is a novel strategy to generate liver organ substitutes that can potentially be used in transplantation. Recently, in vivo liver engineering, including in vivo organ decellularization followed by repopulation, has emerged as a promising approach over ex vivo liver engineering. However, postoperative survival was not achieved. The aim of this study is to develop a novel surgical technique of in vivo selective liver lobe perfusion in rats as a prerequisite for in vivo liver engineering. We generate a circuit bypass only through the left lateral lobe. Then, the left lateral lobe is perfused with heparinized saline. The experiment is performed with 4 groups (n = 3 rats per group) based on different perfusion times of 20 min, 2 h, 3 h, and 4 h. Survival, as well as the macroscopically visible change of color and the histologically determined absence of blood cells in the portal triad and the sinusoids, is taken as an indicator for a successful model establishment. After selective perfusion of the left lateral lobe, we observe that the left lateral lobe, indeed, turned from red to faint yellow. In a histological assessment, no blood cells are visible in the branch of the portal vein, the central vein, and the sinusoids. The left lateral lobe turns red after reopening the blocked vessels. 12/12 rats survived the procedure for more than one week. We are the first to report a surgical model for in vivo single liver lobe perfusion with a long survival period of more than one week. In contrast to the previously published report, the most important advantage of the technique presented here is that perfusion of 70% of the liver is maintained throughout the whole procedure. The establishment of this technique provides a foundation for in vivo partial liver engineering in rats, including decellularization and recellularization.

A Novel Surgical Technique As a Foundation for In Vivo Partial Liver Engineering in Rat

We establish a novel surgical technique for an in vivo single liver lobe perfusion model in rat as a prerequisite for further studying in vivo partial liver engineering in the future.

Organ engineering is a novel strategy to generate liver organ substitutes that can potentially be used in transplantation. Recently, in vivo liver ...

Gene Expression Analysis of Endothelial Cells Exposed to Shear Stress Using Multiple Parallel-plate Flow Chambers

We describe a workflow for the analysis of gene expression from endothelial cells subject to a steady laminar flow using multiple monitored parallel-plate flow chambers. Endothelial cells form the inner cellular lining of blood vessels and are chronically exposed to the frictional force of blood flow called shear stress. Under physiological conditions, endothelial cells function in the presence of various shear stress conditions. Thus, the application of shear stress conditions in in vitro models can provide greater insight into endothelial responses in vivo. The parallel-plate flow chamber previously published by Lane et al.9 is adapted to study endothelial gene regulation in the presence and absence of steady (non-pulsatile) laminar flow. Key adaptations in the set-up for laminar flow as presented here include a large, dedicated environment to house concurrent flow circuits, the monitoring of flow rates in real-time, and the inclusion of an exogenous reference RNA for the normalization of quantitative real-time PCR data. To assess multiple treatments/conditions with the application of shear stress, multiple flow circuits and pumps are used simultaneously within the same heated and humidified incubator. The flow rate of each flow circuit is measured continuously in real-time to standardize shear stress conditions throughout the experiments. Because these experiments have multiple conditions, we also use an exogenous reference RNA that is spiked-in at the time of RNA extraction for the normalization of RNA extraction and first-strand cDNA synthesis efficiencies. These steps minimize the variability between samples. This strategy is employed in our pipeline for the gene expression analysis with shear stress experiments using the parallel-plate flow chamber, but parts of this strategy, such as the exogenous reference RNA spike-in, can easily and cost-effectively be used for other applications.

Here, a workflow for the culture and gene expression analysis of endothelial cells under fluid shear stress is presented. Included is a physical arrangement for simultaneously housing and monitoring multiple flow chambers in a controlled environment and the use of an exogenous reference RNA for quantitative PCR.

We describe a workflow for the analysis of gene expression from endothelial cells subject to a steady laminar flow using multiple monitored parallel-plate ...