Name: mechanostimulation of multicellular organisms through a high-throughput microfluidic compression system
Uploaded: 2022-12-23T13:15:00
Description: Watch this Scientific Journal Video about Mechanostimulation of Multicellular Organisms Through a High-Throughput Microfluidic Compression System at JoVE.com

This work was supported by the National Science Foundation (CMMI-1946456), the Air Force Office of Scientific Research (FA9550-18-1-0262), and the National Institute of Health (R01AG06100501A1; R21AR08105201A1).

1. Preparation of the silicon wafer mold
<ol>
	<li>Clean the silicon wafer (see Table of Materials) first with acetone and then with isopropyl alcohol (IPA).</li>
	<li>Place the silicon wafer on a 250 &#176;C hot plate for 30 min for dehydration bake (Figure 3A).</li>
	<li>Coat the silicon wafer with hexamethyldisilazane (HDMS) in a vapor prime oven (see Table of Materials) (process temperature: 150 &#176;C, process pressure: 2 Torr, proce...

<ol>
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H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Drosophila-A+versatile+model+in+biology+&amp;+medicine.">Drosophila-A versatile model in biology &amp; medicine.</a> Materials Today. 14 (5), 190-195 (2011).</li><li>Konno, 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=State-of-the-art+technology+of+model+organisms+for+current+human+medicine.">State-of-the-art technology of model organisms for current human medicine.</a> Diagnostics. 10 (6), 392 (2020).</li><li>Morgan, T. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sex+limited+inheritance+in+Drosophila.">Sex limited inheritance in Drosophila.</a> Science. 32 (812), 120-122 (1910).</li><li>Wu, Q., Kumar, N., Velagala, V., Zartman, J. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tools+to+reverse-engineer+multicellular+systems:+Case+studies+using+the+fruit+fly.">Tools to reverse-engineer multicellular systems: Case studies using the fruit fly.</a> Journal of Biological Engineering. 13 (1), 1-16 (2019).</li><li>Jayamohan, H., et al., Patrinos, 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=Chapter+11+-+Advances+in+Microfluidics+and+Lab-on-a-Chip+Technologies.">Chapter 11 - Advances in Microfluidics and Lab-on-a-Chip Technologies.</a> Molecular Diagnostics. , 197-217 (2017).</li><li>Scheler, O., Postek, W., Garstecki, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recent+developments+of+microfluidics+as+a+tool+for+biotechnology+and+microbiology.">Recent developments of microfluidics as a tool for biotechnology and microbiology.</a> Current Opinion in Biotechnology. 55, 60-67 (2019).</li><li>Mohammed, 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=Innovative+tools+for+mechanobiology:+Unraveling+outside-in+and+inside-out+mechanotransduction.">Innovative tools for mechanobiology: Unraveling outside-in and inside-out mechanotransduction.</a> Frontiers in Bioengineering and Biotechnology. 7, 162 (2019).</li><li>Shorr, A. Z., S&#246;nmez, U. M., Minden, J. S., LeDuc, P. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High-throughput+mechanotransduction+in+Drosophila+embryos+with+mesofluidics.">High-throughput mechanotransduction in Drosophila embryos with mesofluidics.</a> Lab on a Chip. 19 (7), 1141-1152 (2019).</li><li>Kim, Y. T., 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=Mechanochemical+Actuators+of+Embryonic+Epithelial+Contractility.">Mechanochemical Actuators of Embryonic Epithelial Contractility.</a> Proceedings of the National Academy of Sciences. 40, 14366-14371 (2014).</li><li>Ashburner, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Drosophila. A Laboratory Handbook. , (1989).</li><li>Qin, D., Xia, Y., Whitesides, G. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Soft+lithography+for+micro-and+nanoscale+patterning.">Soft lithography for micro-and nanoscale patterning.</a> Nature Protocols. 5 (3), 491 (2010).</li><li>Lee, 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=A+new+fabrication+process+for+uniform+SU-8+thick+photoresist+structures+by+simultaneously+removing+edge+bead+and+air+bubbles.">A new fabrication process for uniform SU-8 thick photoresist structures by simultaneously removing edge bead and air bubbles.</a> Journal of Micromechanics and Microengineering. 21 (12), 125006 (2011).</li><li>Xia, Y., Whitesides, G. 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The article describes the development of a microfluidic device to automatically align, immobilize, and precisely apply mechanical stimulation to hundreds of whole Drosophila embryos. The integration of the microfluidic system with a thin glass coverslip allowed for the imaging of embryos with high-resolution confocal microscopy during the stimulation. The microfluidic device also enabled the collection of the embryos right after the stimulation for running downstream biological assays. The design considerations,...

Living systems constantly experience and respond to various mechanical inputs throughout their lifetimes1. Mechanotransduction has been linked to many diseases, including developmental disorders, muscle and bone loss, and neuropathologies through signaling pathways directly or indirectly affected by the mechanical environment2. However, the genes and proteins that are regulated by mechanical stimulation3 in the mechanosensitive signaling pathways4 remain largely unknown5, preventing the elucidation of the mechanical regulation mechanisms and the identification of molecular targets for diseases associated with pathological mechanotransduction6,7. One limiting factor in projecting mechanobiology studies onto the related physiological processes is using individual cells with conventional culture dishes instead of intact multicellular organisms. Model organisms, such as Drosophila melanogaster (fruit fly), have contributed greatly to understanding the genes, signaling pathways, and proteins involved in animal development8,9,10. Nevertheless, using Drosophila and other multicellular model organisms in mechanobiology research has been hindered by challenges with experimental tools. Conventional techniques for preparing, sorting, imaging, or applying various stimuli require mostly manual manipulation; these approaches are time-consuming, require expertise, introduce variability, and limit the experimental design and sample size11. Recent microtechnological advancements are a great resource for enabling novel biological assays with very high throughput and highly controlled experimental parameters12,13,14.
This article describes the development of an enhanced microfluidic device to align, immobilize, and precisely apply mechanical stimulation in the form of uniaxial compression to hundreds of whole Drosophila embryos15&#160;(Figure 1). Integration of the microfluidic system with a glass coverslip allowed high-resolution confocal imaging of the samples during the stimulation. The microfluidic device also enabled fast collection of the embryos after the stimulation for running -omics assays (Figure 2). Explanations of the design considerations of this device, as well as the fabrication using soft lithography and experimental characterization, are described herein. Since making a silicon wafer mold of such a device requires a uniform coating of thick photoresist (thickness &#62;200 &#181;m) over large areas with high aspect ratio (AR) trenches (AR &#62;5), this method considerably modified the traditional photolithographic mold fabrication protocol. In this way, this method facilitated the handling, adhesion, coating, patterning, and development of the photoresist. Additionally, potential pitfalls and their solutions are discussed. Lastly, the versatility of this design and fabrication strategy was demonstrated using other multicellular systems such as Drosophila egg chambers and brain organoids16.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>100 mL tri-cornered perforated plastic beakers with 60 mm Petri dishes</td>
			<td>Fisher</td>
			<td>14-955-111B</td>
			<td>Perferate with air holes</td>
		</tr>
		<tr>
			<td>100 mm P B &#60;100&#62; 0-100 500um SSP Test Grade Si Wafer</td>
			<td>University Wafer</td>
			<td>452</td>
			<td></td>
		</tr>
		<tr>
			<td>Biopsy punches</td>
			<td>Ted Pella</td>
			<td>15110</td>
			<td></td>
		</tr>
		<tr>
			<td>Bleach</td>
			<td></td>
			<td></td>
			<td>Not brand specific</td>
		</tr>
		<tr>
			<td>Blunt needle set</td>
			<td>CML Supply</td>
			<td>901</td>
			<td></td>
		</tr>
		<tr>
			<td>Contact Mask Aligner</td>
			<td>Quintel</td>
			<td>Q4000 MA</td>
			<td></td>
		</tr>
		<tr>
			<td>Cutting mat</td>
			<td>Dahle</td>
			<td>Vantage 10670</td>
			<td>size: 24&#34; x 36&#34;</td>
		</tr>
		<tr>
			<td>Developer</td>
			<td>Kayaku Advance Materials</td>
			<td>SU-8 2000</td>
			<td></td>
		</tr>
		<tr>
			<td>Direct Write Lithographer</td>
			<td>Heidelberg</td>
			<td>MLA100</td>
			<td></td>
		</tr>
		<tr>
			<td>Dissecting microscope</td>
			<td></td>
			<td></td>
			<td>Any commericailly availble dissecting microscope with transmitted light</td>
		</tr>
		<tr>
			<td>Glass petri dish</td>
			<td>Fisher</td>
			<td>FB0875713A</td>
			<td></td>
		</tr>
		<tr>
			<td>Glass slide</td>
			<td>Warner Instruments</td>
			<td>64-0710&#160; (CS-24/60)</td>
			<td></td>
		</tr>
		<tr>
			<td>HMDS Vapor Prime Oven</td>
			<td>Yes Engineering</td>
			<td>YES-3TA</td>
			<td></td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td></td>
			<td></td>
			<td>Not brand specific</td>
		</tr>
		<tr>
			<td>Oven</td>
			<td>Labnet</td>
			<td>I5110A</td>
			<td></td>
		</tr>
		<tr>
			<td>Paintbrush</td>
			<td></td>
			<td></td>
			<td>Not brand specific</td>
		</tr>
		<tr>
			<td>PDMS</td>
			<td>Dow Corning</td>
			<td>Sylgard 184</td>
			<td></td>
		</tr>
		<tr>
			<td>Photoresist</td>
			<td>MicroChem</td>
			<td>SU-8 2100</td>
			<td></td>
		</tr>
		<tr>
			<td>Plasma cleaner</td>
			<td>Harrick Plasma</td>
			<td>PDC-32G</td>
			<td></td>
		</tr>
		<tr>
			<td>Portable pressure source</td>
			<td>hygger Quietest</td>
			<td>HGD946</td>
			<td></td>
		</tr>
		<tr>
			<td>Pressure gauge</td>
			<td>Cole-Parmer</td>
			<td>EW-68950-25</td>
			<td></td>
		</tr>
		<tr>
			<td>Spin Coater</td>
			<td>Laurell</td>
			<td>WS-650-8B</td>
			<td></td>
		</tr>
		<tr>
			<td>Trichloro(1H,1H,2H,2H-perfluorooctyl)silane (PFOCTS)</td>
			<td>Sigma-Aldrich</td>
			<td>448931-10G</td>
			<td></td>
		</tr>
		<tr>
			<td>Triton-X 100</td>
			<td>Fisher</td>
			<td>AAA16046AP</td>
			<td></td>
		</tr>
		<tr>
			<td>Tubing</td>
			<td>Saint-Gobain</td>
			<td>02-587-1A</td>
			<td></td>
		</tr>
		<tr>
			<td>Ultrasonic Cleaner</td>
			<td>Cole-Parmer</td>
			<td>UX-08895-05</td>
			<td></td>
		</tr>
		<tr>
			<td>Vacuum Pump</td>
			<td>Cole-Parmer</td>
			<td>EW-07164-87</td>
			<td></td>
		</tr>
	</tbody>
</table>

mechanostimulation of multicellular organisms through a high-throughput microfluidic compression system

During embryogenesis, coordinated cell movement generates mechanical forces that regulate gene expression and activity. To study this process, tools such as aspiration or coverslip compression have been used to mechanically stimulate whole embryos. These approaches limit experimental design as they are imprecise, require manual handling, and can process only a couple of embryos simultaneously. Microfluidic systems have great potential for automating such experimental tasks while increasing throughput and precision. This article describes a microfluidic system developed to precisely compress whole Drosophila melanogaster (fruit fly) embryos. This system features microchannels with pneumatically actuated deformable sidewalls and enables embryo alignment, immobilization, compression, and post-stimulation collection. By parallelizing these microchannels into seven lanes, steady or dynamic compression patterns can be applied to hundreds of Drosophila embryos simultaneously. Fabricating this system on a glass coverslip facilitates the simultaneous mechanical stimulation and imaging of samples with high-resolution microscopes. Moreover, the utilization of biocompatible materials, like PDMS, and the ability to flow fluid through the system make this device capable of long-term experiments with media-dependent samples. This approach also eliminates the requirement for manual mounting which mechanically stresses samples. Furthermore, the ability to quickly collect samples from the microchannels enables post-stimulation analyses, including -omics assays which require large sample numbers unattainable using traditional mechanical stimulation approaches. The geometry of this system is readily scalable to different biological systems, enabling numerous fields to benefit from the functional features described herein including high sample throughput, mechanical stimulation or immobilization, and automated alignment.

The microfluidic system is divided into two sub-compartments separated by deformable PDMS sidewalls. The first compartment is the liquid system where Drosophila embryos are introduced, automatically aligned, lined up, and compressed. The second compartment is a gas system where the gas pressure at either side of the compression channels is controlled via dead-end microchannels to precisely control the effective width of the compression channels. The microfluidic device is sealed with a glass slide at th...

Watch this Scientific Journal Video about Mechanostimulation of Multicellular Organisms Through a High-Throughput Microfluidic Compression System at JoVE.com

Mechanostimulation of Multicellular Organisms Through a High-Throughput Microfluidic Compression System

The present protocol describes the design, fabrication, and characterization of a microfluidic system capable of aligning, immobilizing, and precisely compressing hundreds of Drosophila melanogaster embryos with minimal user intervention. This system enables high-resolution imaging and recovery of samples for post-stimulation analysis and can be scaled to accommodate other multicellular biological systems.

During embryogenesis, coordinated cell movement generates mechanical forces that regulate gene expression and activity. To study this process, tools such ...

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