Name: a microfluidic platform for stimulating chondrocytes with dynamic compression
Uploaded: 2019-09-13T13:00:00
Description: Watch this Scientific Journal Video about A Microfluidic Platform for Stimulating Chondrocytes with Dynamic Compression at JoVE.com

We thank Drs. Christopher Moraes and Stephen A. Morin for their support for device design and fabrication. This study was supported by Bioengineering for Human Health grant from the University of Nebraska-Lincoln (UNL) and the University of Nebraska Medical Center (UNMC), and grant AR070242 from the NIH/NIAMS. We thank Janice A. Taylor and James R. Talaska of the Advanced Microscopy Core Facility at the University of Nebraska Medical Center for providing assistance with confocal microscopy.

NOTE: Wear personal protective equipment (PPE) such as gloves and lab coat for every step in this protocol.
1. Master mold fabrication
NOTE: Perform step 1.1 - 1.3 in a fume hood.
<ol>
	<li>Glass treatment 
	NOTE: Wear a face shield, gloves, and a lab coat for step 1.1.
	<ol>
		<li>Make Piranha solution (60 mL) by mixing sulfuric acid (H2SO4) and hydrogen peroxide (H2O2) with a volume ratio of 3:1. 
		CAUTION: ...

<ol>
	<li>Lu, H., 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=Microfluidic+shear+devices+for+quantitative+analysis+of+cell+adhesion.">Microfluidic shear devices for quantitative analysis of cell adhesion.</a> Analytical Chemistry. 76 (18), 5257-5264 (2004).</li><li>Malek, A. M., Izumo, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanism+of+endothelial+cell+shape+change+and+cytoskeletal+remodeling+in+response+to+fluid+shear+stress.">Mechanism of endothelial cell shape change and cytoskeletal remodeling in response to fluid shear stress.</a> Journal of Cell Science. 109 (4), 713-726 (1996).</li><li>Paguirigan, A. L., Beebe, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microfluidics+meet+cell+biology:+bridging+the+gap+by+validation+and+application+of+microscale+techniques+for+cell+biological+assays.">Microfluidics meet cell biology: bridging the gap by validation and application of microscale techniques for cell biological assays.</a> BioEssays. 30 (9), 811-821 (2008).</li><li>Garc&#237;a-Carde&#241;a, G., Comander, J., Anderson, K. R., Blackman, B. R., Gimbrone, 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=Biomechanical+activation+of+vascular+endothelium+as+a+determinant+of+its+functional+phenotype.">Biomechanical activation of vascular endothelium as a determinant of its functional phenotype.</a> Proceedings of the National Academy of Sciences. 98 (8), 4478-4485 (2001).</li><li>Huh, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reconstituting+organ-level+lung+functions+on+a+chip.">Reconstituting organ-level lung functions on a chip.</a> Science. 328 (5986), 1662-1668 (2010).</li><li>Moraes, C., Chen, J. H., Sun, Y., Simmons, C. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microfabricated+arrays+for+high-throughput+screening+of+cellular+response+to+cyclic+substrate+deformation.">Microfabricated arrays for high-throughput screening of cellular response to cyclic substrate deformation.</a> Lab on a Chip. 10 (2), 227-234 (2010).</li><li>Moraes, C., Wang, G., Sun, Y., Simmons, C. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+microfabricated+platform+for+high-throughput+unconfined+compression+of+micropatterned+biomaterial+arrays.">A microfabricated platform for high-throughput unconfined compression of micropatterned biomaterial arrays.</a> Biomaterials. 31 (3), 577-584 (2010).</li><li>Sundararaghavan, H. G., Monteiro, G. A., Firestein, B. L., Shreiber, D. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neurite+growth+in+3D+collagen+gels+with+gradients+of+mechanical+properties.">Neurite growth in 3D collagen gels with gradients of mechanical properties.</a> Biotechnology and Bioengineering. 102 (2), 632-643 (2009).</li><li>Bougault, C., Paumier, A., Aubert-Foucher, E., Mallein-Gerin, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+analysis+of+chondrocytes+cultured+in+agarose+in+response+to+dynamic+compression.">Molecular analysis of chondrocytes cultured in agarose in response to dynamic compression.</a> BMC Biotechnology. 8 (1), 71 (2008).</li><li>Kaviani, R., Londono, I., Parent, S., Moldovan, F., Villemure, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Compressive+mechanical+modulation+alters+the+viability+of+growth+plate+chondrocytes+in+vitro.">Compressive mechanical modulation alters the viability of growth plate chondrocytes in vitro.</a> Journal of Orthopaedic Research. 33 (11), 1587-1593 (2015).</li><li>M&#233;nard, A. L., 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=In+vivo+dynamic+loading+reduces+bone+growth+without+histomorphometric+changes+of+the+growth+plate.">In vivo dynamic loading reduces bone growth without histomorphometric changes of the growth plate.</a> Journal of Orthopaedic Research. 32 (9), 1129-1136 (2014).</li><li>Robling, A. G., Duijvelaar, K. M., Geevers, J. V., Ohashi, N., Turner, C. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modulation+of+appositional+and+longitudinal+bone+growth+in+the+rat+ulna+by+applied+static+and+dynamic+force.">Modulation of appositional and longitudinal bone growth in the rat ulna by applied static and dynamic force.</a> Bone. 29 (2), 105-113 (2001).</li><li>Sergerie, K., 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=Growth+plate+explants+respond+differently+to+in+vitro+static+and+dynamic+loadings.">Growth plate explants respond differently to in vitro static and dynamic loadings.</a> Journal of Orthopaedic Research. 29 (4), 473-480 (2011).</li><li>Valteau, B., Grimard, G., Londono, I., Moldovan, F., Villemure, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vivo+dynamic+bone+growth+modulation+is+less+detrimental+but+as+effective+as+static+growth+modulation.">In vivo dynamic bone growth modulation is less detrimental but as effective as static growth modulation.</a> Bone. 49 (5), 996-1004 (2011).</li><li>Walsh, A. J. L., Lotz, J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biological+response+of+the+intervertebral+disc+to+dynamic+loading.">Biological response of the intervertebral disc to dynamic loading.</a> Journal of Biomechanics. 37 (3), 329-337 (2004).</li><li>Zimmermann, E. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+situ+deformation+of+growth+plate+chondrocytes+in+stress-controlled+static+vs+dynamic+compression.">In situ deformation of growth plate chondrocytes in stress-controlled static vs dynamic compression.</a> Journal of Biomechanics. 56, 76-82 (2017).</li><li>Akyuz, E., Braun, J. T., Brown, N. A. T., Bachus, K. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Static+versus+dynamic+loading+in+the+mechanical+modulation+of+vertebral+growth.">Static versus dynamic loading in the mechanical modulation of vertebral growth.</a> Spine. 31 (25), E952-E958 (2006).</li><li>Alberty, A., Peltonen, J., Ritsil&#228;, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+distraction+and+compression+on+proliferation+of+growth+plate+chondrocytes:+A+study+in+rabbits.">Effects of distraction and compression on proliferation of growth plate chondrocytes: A study in rabbits.</a> Acta Orthopaedica Scandinavica. 64 (4), 449-455 (1993).</li><li>Amini, S., Veilleux, D., Villemure, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tissue+and+cellular+morphological+changes+in+growth+plate+explants+under+compression.">Tissue and cellular morphological changes in growth plate explants under compression.</a> Journal of Biomechanics. 43 (13), 2582-2588 (2010).</li><li>Aronsson, D. D., Stokes, I. A. F., Rosovsky, J., Spence, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanical+modulation+of+calf+tail+vertebral+growth:+implications+for+scoliosis+progression.">Mechanical modulation of calf tail vertebral growth: implications for scoliosis progression.</a> Journal of Spinal Disorders. 12 (2), 141-146 (1999).</li><li>Cancel, M., Grimard, G., Thuillard-Crisinel, D., Moldovan, F., Villemure, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+in+vivo+static+compressive+loading+on+aggrecan+and+type+II+and+X+collagens+in+the+rat+growth+plate+extracellular+matrix.">Effects of in vivo static compressive loading on aggrecan and type II and X collagens in the rat growth plate extracellular matrix.</a> Bone. 44 (2), 306-315 (2009).</li><li>Reich, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Weight+loading+young+chicks+inhibits+bone+elongation+and+promotes+growth+plate+ossification+and+vascularization.">Weight loading young chicks inhibits bone elongation and promotes growth plate ossification and vascularization.</a> Journal of Applied Physiology. 98 (6), 2381-2389 (2005).</li><li>Stokes, I. A., Mente, P. L., Iatridis, J. C., Farnum, C. E., Aronsson, D. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enlargement+of+growth+plate+chondrocytes+modulated+by+sustained+mechanical+loading.">Enlargement of growth plate chondrocytes modulated by sustained mechanical loading.</a> Journal of Bone and Joint Surgery. 84 (10), 1842-1848 (2002).</li><li>Stokes, I. A. F., Clark, K. C., Farnum, C. E., Aronsson, D. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Alterations+in+the+growth+plate+associated+with+growth+modulation+by+sustained+compression+or+distraction.">Alterations in the growth plate associated with growth modulation by sustained compression or distraction.</a> Bone. 41 (2), 197-205 (2007).</li><li>Lee, D., Erickson, A., Dudley, A. T., Ryu, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanical+stimulation+of+growth+plate+chondrocytes:+previous+approaches+and+future+directions.">Mechanical stimulation of growth plate chondrocytes: previous approaches and future directions.</a> Experimental Mechanics. , (2018).</li><li>Lee, D., Erickson, A., You, T., Dudley, A. T., Ryu, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pneumatic+microfluidic+cell+compression+device+for+high-throughput+study+of+chondrocyte+mechanobiology.">Pneumatic microfluidic cell compression device for high-throughput study of chondrocyte mechanobiology.</a> Lab on a Chip. 18 (14), 2077-2086 (2018).</li><li>Guilak, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Compression-induced+changes+in+the+shape+and+volume+of+the+chondrocyte+nucleus.">Compression-induced changes in the shape and volume of the chondrocyte nucleus.</a> Journal of Biomechanics. 28 (12), 1529-1541 (1995).</li><li>Knight, M. M., Ghori, S. A., Lee, D. A., Bader, D. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+of+the+deformation+of+isolated+chondrocytes+in+agarose+subjected+to+cyclic+compression.">Measurement of the deformation of isolated chondrocytes in agarose subjected to cyclic compression.</a> Medical Engineering &amp; Physics. 20 (9), 684-688 (1998).</li><li>Moraes, C., Sun, Y., Simmons, C. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microfabricated+platforms+for+mechanically+dynamic+cell+culture.">Microfabricated platforms for mechanically dynamic cell culture.</a> Journal of Visualized Experiments. (46), e224 (2010).</li><li>Sim, W. Y., 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+pneumatic+micro+cell+chip+for+the+differentiation+of+human+mesenchymal+stem+cells+under+mechanical+stimulation.">A pneumatic micro cell chip for the differentiation of human mesenchymal stem cells under mechanical stimulation.</a> Lab on a Chip. 7 (12), 1775-1782 (2007).</li><li>Hosmane, S., 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=Valve-based+microfluidic+compression+platform:+single+axon+injury+and+regrowth.">Valve-based microfluidic compression platform: single axon injury and regrowth.</a> Lab on a Chip. 11 (22), 3888-3895 (2011).</li><li>Ho, K. K. Y., Wang, Y. L., Wu, J., Liu, A. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Advanced+microfluidic+device+designed+for+cyclic+compression+of+single+adherent+cells.">Advanced microfluidic device designed for cyclic compression of single adherent cells.</a> Frontiers in Bioengineering and Biotechnology. 6 (148), (2018).</li><li>Seo, 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=Interconnectable+dynamic+compression+bioreactors+for+combinatorial+screening+of+cell+mechanobiology+in+three+dimensions.">Interconnectable dynamic compression bioreactors for combinatorial screening of cell mechanobiology in three dimensions.</a> ACS Applied Materials &amp; Interfaces. 10 (16), 13293-13303 (2018).</li><li>Erickson, A. 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=A+tunable,+three-dimensional+in+Vitro+culture+model+of+growth+plate+cartilage+using+alginate+hydrogel+acaffolds.">A tunable, three-dimensional in Vitro culture model of growth plate cartilage using alginate hydrogel acaffolds.</a> Tissue Engineering Part A. 24 (1-2), 94-105 (2018).</li><li>Lee, D., Rahman, M. M., Zhou, Y., Ryu, S. <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+confocal+microscopy+indentation+method+for+hydrogel+elasticity+measurement.">Three-dimensional confocal microscopy indentation method for hydrogel elasticity measurement.</a> Langmuir. 31 (35), 9684-9693 (2015).</li><li>Johnston, I. D., McCluskey, D. K., Tan, C. K. L., Tracey, M. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanical+characterization+of+bulk+Sylgard+184+for+microfluidics+and+microengineering.">Mechanical characterization of bulk Sylgard 184 for microfluidics and microengineering.</a> Journal of Micromechanics and Microengineering. 24 (3), 035017 (2014).</li></ol>

To test the effects of compressive stress on growth plate chondrocytes, we developed the microfluidic chondrocyte compression device (Figure 1) to apply various levels of compressive stress to the chondrocytes in the alginate hydrogel scaffold for 3D culture in high throughput ways. To assist other researchers to adopt our device or to develop similar devices, we provided details of the device fabrication steps in this protocol article.
The crucial steps in this p...

Micro-engineered platforms are valuable tools for studying the molecular, cellular, and tissue level biology because they enable dynamic control of both the physical and chemical microenvironments1,2,3,4,5,6,7,8. Thus, multiple hypotheses can be simultaneously tested in a tightly controlled manner. In the case of growth plate cartilage, there are increasing evidences of an important role of compressive stress in modulating bone growth through action on the growth plate cartilage9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25. However, the mechanism of action of compressive stress &#8211; in particular, how stress guides the formation of chondrocyte columns in the growth plate &#8211; is poorly understood.
The goal of this protocol is to create a pneumatically actuating microfluidic chondrocyte compression device26 to elucidate mechanisms of mechanobiology in growth plate chondrocytes (Figure 1a-c). The device consists of two parts: the pneumatic actuation unit and the alginate gel construct. The microfluidic pneumatic actuation unit is fabricated using polydimethylsiloxane (PDMS) based on the photo- and soft-lithography. This unit contains a 5 x 5 array of thin PDMS membrane balloons which can be inflated differently based on their diameters. The alginate gel construct consists of the chondrocytes embedded in a 5 x&#160;5 array of alginate gel cylinders, and the entire alginate-chondrocyte constructs are assembled with the actuation unit. The alginate gel constructs are compressed by the pneumatically inflated PDMS balloons (Figure 1b). The microfluidic device can generate five different levels of compressive stress simultaneously in a single platform based on differences in the PDMS balloon diameter. Thus, a high-throughput test of chondrocyte mechanobiology under multiple compression conditions is possible.
The microfluidic device described in this protocol has many advantages over the conventional compression device such as external fixators14,21,23 and macroscopic compression devices16,19,27,28 for studying chondrocyte mechanobiology: 1) The microfluidic device is cost effective because it consumes smaller volume of samples than the macroscopic compression device, 2) The microfluidic device is time effective because it can test multiple compression conditions simultaneously, 3) The microfluidic device can combine mechanical and chemical stimuli by forming a concentration gradient of chemicals based on the limited mixing in microchannels, and 4) Various microscopy techniques (time-lapse microscopy and fluorescence confocal microscopy) can be applied with the microfluidic device made of transparent PDMS.
We adopted and modified the method of Moraes et al.7,29 to create different compressive stress levels in a single device to enable high-throughput mechanobiology studies of chondrocyte compression. Our approach is appropriate for cells (e.g., chondrocytes) which need three-dimensional (3D) culture environment and for biological assays after compressing cells. Although some microfluidic cell compression devices can compress cells cultured on two-dimensional (2D) substrates30,31,32, they cannot be used for chondrocytes because 2D cultured chondrocytes dedifferentiate. There are microfluidic platforms for compressing 3D cultured cells in photopolymerized hydrogels7,33, but they are limited in isolating cells after compression experiments because isolating cells from photopolymerized hydrogel is not easy. Additionally, the effects of ultraviolet (UV) exposure and photo crosslinking initiators on cells may need to be evaluated. In contrast, our method allows rapid isolation of cells after compression experiments for post biological assays because alginate hydrogels can be depolymerized quickly by calcium chelators. The detailed device fabrication and characterization methods are described in this protocol. A brief procedure for fabricating the microfluidic chondrocyte compression device is shown in Figure 2.

<table>
	<tbody>
		<tr>
			<td>(3-Aminopropyl)triethoxysilane (ATPES)</td>
			<td>Sigma-Aldrich</td>
			<td>741442-100ML</td>
			<td></td>
		</tr>
		<tr>
			<td>(Tridecafluoro-1, 1, 2, 2-Tetrahydrooctyl)-1-Trichlorosilane</td>
			<td>United Chemical Technologies</td>
			<td>T2492-KG</td>
			<td></td>
		</tr>
		<tr>
			<td>Acrylic sheet</td>
			<td>McMaster-Carr</td>
			<td>8560K354</td>
			<td></td>
		</tr>
		<tr>
			<td>Air pump</td>
			<td>Schwarzer Precision</td>
			<td>SP 500 EC-LC4.5V DC</td>
			<td>We used the model purchased in 2015. The internal design and performance of air pump (SP 500 EC-LC) changed in early 2016. Also, air pump performance has changed in the course of time. Thus, air pressure generated by an SP 500 EC-LC air pump should be calibrated before use.</td>
		</tr>
		<tr>
			<td>Alginate powder</td>
			<td>FMC Corporation</td>
			<td>Pronova UP MVG</td>
			<td></td>
		</tr>
		<tr>
			<td>Barb Straight Connectors (Metal tube)</td>
			<td>Pneumadyne</td>
			<td>EB40-250</td>
			<td></td>
		</tr>
		<tr>
			<td>Calcein AM</td>
			<td>Invitrogen</td>
			<td>C3100MP</td>
			<td></td>
		</tr>
		<tr>
			<td>Dulbecco&#39;s Modified Eagle Medium (DMEM)</td>
			<td>Gibco</td>
			<td>11960-044</td>
			<td></td>
		</tr>
		<tr>
			<td>Dyed red aqueous fluorescent particles</td>
			<td>Thermo Fisher Scientific</td>
			<td>R0100</td>
			<td></td>
		</tr>
		<tr>
			<td>EDC (1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride)</td>
			<td>Thermo Fisher Scientific</td>
			<td>22980</td>
			<td></td>
		</tr>
		<tr>
			<td>Foam pad</td>
			<td>GRAINGER</td>
			<td>Item # 5GCE8</td>
			<td></td>
		</tr>
		<tr>
			<td>Function / Arbitrary Waveform Generator</td>
			<td>Keysight Technologies</td>
			<td>33210A</td>
			<td></td>
		</tr>
		<tr>
			<td>Hydrochloric acid</td>
			<td>Fisher Chemical</td>
			<td>A144-500</td>
			<td></td>
		</tr>
		<tr>
			<td>Hydrogen peroxide</td>
			<td>Fisher BioReagents</td>
			<td>BP2633500</td>
			<td></td>
		</tr>
		<tr>
			<td>Isopropyl alcohol</td>
			<td>BDH1174-4LP</td>
			<td>VWR</td>
			<td></td>
		</tr>
		<tr>
			<td>Microscope slides</td>
			<td>Thermo Fisher Scientific</td>
			<td>22-267-013</td>
			<td></td>
		</tr>
		<tr>
			<td>Plasma cleaner</td>
			<td>Harrick Plasma</td>
			<td>PDC-001</td>
			<td></td>
		</tr>
		<tr>
			<td>Polydimethylsiloxane (PDMS)</td>
			<td>Dow Corning</td>
			<td>184 SIL ELAST KIT 0.5KG</td>
			<td></td>
		</tr>
		<tr>
			<td>Power supply</td>
			<td>Keysight Technologies</td>
			<td>E3630A</td>
			<td></td>
		</tr>
		<tr>
			<td>SeaKem LE Agarose</td>
			<td>Lonza</td>
			<td>50004</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium hydroxide</td>
			<td>Fisher Chemical</td>
			<td>S318-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Solenoid manifold</td>
			<td>Pneumadyne</td>
			<td>MSV10-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Solenoid valve</td>
			<td>Pneumadyne</td>
			<td>S10MM-30-12-3</td>
			<td></td>
		</tr>
		<tr>
			<td>Spin coater</td>
			<td>Laurell Technologies</td>
			<td>WS-650Mz-23NPPB</td>
			<td></td>
		</tr>
		<tr>
			<td>SU8 Developer</td>
			<td>MicroChem Corp.</td>
			<td>Y020100 4000L1PE</td>
			<td></td>
		</tr>
		<tr>
			<td>SU8-100</td>
			<td>MicroChem Corp.</td>
			<td>Y131273 0500L1GL</td>
			<td></td>
		</tr>
		<tr>
			<td>SU8-5</td>
			<td>MicroChem Corp.</td>
			<td>Y131252 0500L1GL</td>
			<td></td>
		</tr>
		<tr>
			<td>Sulfo-NHS (N-hydroxysulfosuccinimide)</td>
			<td>Thermo Fisher Scientific</td>
			<td>24510</td>
			<td></td>
		</tr>
		<tr>
			<td>Sulfuric acid</td>
			<td>EMD Millipore</td>
			<td>MSX12445</td>
			<td></td>
		</tr>
	</tbody>
</table>

a microfluidic platform for stimulating chondrocytes with dynamic compression

Mechanical stimuli are known to modulate biological functions of cells and tissues. Recent studies have suggested that compressive stress alters growth plate cartilage architecture and results in growth modulation of long bones of children. To determine the role of compressive stress in bone growth, we created a microfluidic device actuated by pneumatic pressure, to dynamically (or statically) compress growth plate chondrocytes embedded in alginate hydrogel cylinders. In this article, we describe detailed methods for fabricating and characterizing this device. The advantages of our protocol are: 1) Five different magnitudes of compressive stress can be generated on five technical replicates in a single platform, 2) It is easy to visualize cell morphology via a conventional light microscope, 3) Cells can be rapidly isolated from the device after compression to facilitate downstream assays, and 4) The platform can be applied to study mechanobiology of any cell type that can grow in hydrogels.

This article shows detailed steps of the microfluidic chondrocyte compression device fabrication (Figure 2). The device contains a 5 x&#160;5 arrays of cylindrical alginate-chondrocyte constructs, and these constructs can be compressed with five different magnitudes of compression (Figure 1, Figure 3 and Figure 4). The height of the pneumatic microchannel is around 90 &#956;m, and the PDMS balloon diame...

Watch this Scientific Journal Video about A Microfluidic Platform for Stimulating Chondrocytes with Dynamic Compression at JoVE.com

A Microfluidic Platform for Stimulating Chondrocytes with Dynamic Compression

This article provides detailed methods for fabricating and characterizing a pneumatically actuating microfluidic device for chondrocyte compression.

Mechanical stimuli are known to modulate biological functions of cells and tissues. Recent studies have suggested that compressive stress alters growth ...

Research

JoVE Journal

Bioengineering

High-throughput Protein Expression Generator Using a Microfluidic Platform

Rapidly increasing fields, such as systems biology, require the development and implementation of new technologies, enabling high-throughput and ...

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 ...

Microfluidic Platform for Measuring Neutrophil Chemotaxis from Unprocessed Whole Blood

Neutrophils play an essential role in protection against infections and their numbers in the blood are frequently measured in the clinic. Higher ...

The Multi-organ Chip - A Microfluidic Platform for Long-term Multi-tissue Coculture

The ever growing amount of new substances released onto the market and the limited predictability of current in vitro test systems has led to a high need ...

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 ...

Microfluidic Platform with Multiplexed Electronic Detection for Spatial Tracking of Particles

Microfluidic processing of biological samples typically involves differential manipulations of suspended particles under various force fields in order to ...

Imaging the Root Hair Morphology of Arabidopsis Seedlings in a Two-layer Microfluidic Platform

Imaging the Root Hair Morphology of Arabidopsis Seedlings in a Two-layer Microfluidic Platform

Root hairs increase root surface area for better water uptake and nutrient absorption by the plant. Because they are small in size and often obscured by ...

A Microfluidic Platform for Longitudinal Imaging in Caenorhabditis elegans

A Microfluidic Platform for Longitudinal Imaging in Caenorhabditis elegans

In the last decade, microfluidic techniques have been applied to study small animals, including the nematode Caenorhabditis elegans, and have proved ...

An Ultrahigh-throughput Microfluidic Platform for Single-cell Genome Sequencing

Sequencing technologies have undergone a paradigm shift from bulk to single-cell resolution in response to an evolving understanding of the role 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 ...