Name: methylation specific multiplex droplet pcr using polymer droplet generator device for hematological diagnostics
Uploaded: 2020-06-29T14:00:00
Description: Watch this Scientific Journal Video about Methylation Specific Multiplex Droplet PCR using Polymer Droplet Generator Device for Hematological Diagnostics at JoVE.com

The authors acknowledge financial support from the National Research Council of Canada.

All the experiments performed in this study involving human samples were approved by the NRC&#8217;s Ethics Board and were done according to NRC&#8217;s policies governing human subjects that follow applicable research guidelines and are compliant with the laws in Qu&#233;bec, Canada.
1. Cell preparation
<ol>
	<li>Thaw the frozen human peripheral blood mononuclear cells (PBMCs) immediately by placing the cryovial in a water bath at 37 &#176;C for 5 min.</li>
	<li>Invert the cryovial twice to...

<ol>
	<li>Teitell, M., Richardson, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=DNA+methylation+in+the+immune+system.">DNA methylation in the immune system.</a> Clinical Immunology. 109 (1), 2-5 (2003).</li><li>Suarez-Alvarez, B., Rodriguez, R. M., Fraga, M. F., L&#243;pez-Larrea, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=DNA+methylation:+A+promising+landscape+for+immune+system-related+diseases.">DNA methylation: A promising landscape for immune system-related diseases.</a> Trends in Genetics. 28 (10), 506-514 (2012).</li><li>Su&#225;rez-&#193;lvarez, B., Raneros, A. B., Ortega, F., L&#243;pez-Larrea, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Epigenetic+modulation+of+the+immune+function:+A+potential+target+for+tolerance.">Epigenetic modulation of the immune function: A potential target for tolerance.</a> Epigenetics. 8 (7), 694-702 (2013).</li><li>Kondilis-Mangum, H. D., Wade, P. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Epigenetics+and+the+adaptive+immune+response.">Epigenetics and the adaptive immune response.</a> Molecular Aspects of Medicine. 34 (4), 813-825 (2013).</li><li>Zouali, 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> The Autoimmune Diseases. , (2014).</li><li>Wiencke, J. 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=A+comparison+of+DNA+methylation+specific+droplet+digital+PCR+(mdPCR)+and+real+time+qPCR+with+flow+cytometry+in+characterizing+human+T+cells+in+peripheral+blood.">A comparison of DNA methylation specific droplet digital PCR (mdPCR) and real time qPCR with flow cytometry in characterizing human T cells in peripheral blood.</a> Epigenetics. 9 (10), 1360-1365 (2014).</li><li>Hindson, B. 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=High-throughput+droplet+digital+PCR+system+for+absolute+quantitation+of+DNA+copy+number.">High-throughput droplet digital PCR system for absolute quantitation of DNA copy number.</a> Analytical Chemistry. 83 (22), 8604-8610 (2011).</li><li>Pinheiro, L. B., 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=Evaluation+of+a+droplet+digital+polymerase+chain+reaction+format+for+DNA+copy+number+quantification.">Evaluation of a droplet digital polymerase chain reaction format for DNA copy number quantification.</a> Analytical Chemistry. 84 (2), 1003-1011 (2012).</li><li>Roy, E., Galas, J. C., Veres, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thermoplastic+elastomers+for+microfluidics:+Towards+a+high-throughput+fabrication+method+of+multilayered+microfluidic+devices.">Thermoplastic elastomers for microfluidics: Towards a high-throughput fabrication method of multilayered microfluidic devices.</a> Lab on a Chip. 11 (18), 3193-3196 (2011).</li><li>Roy, 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=From+cellular+lysis+to+microarray+detection,+an+integrated+thermoplastic+elastomer+(TPE)+point+of+care+Lab+on+a+Disc.">From cellular lysis to microarray detection, an integrated thermoplastic elastomer (TPE) point of care Lab on a Disc.</a> Lab on a Chip. 15 (2), 406-416 (2015).</li><li>Malic, 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=Epigenetic+subtyping+of+white+blood+cells+using+a+thermoplastic+elastomer-based+microfluidic+emulsification+device+for+multiplexed,+methylation-specific+digital+droplet+PCR.">Epigenetic subtyping of white blood cells using a thermoplastic elastomer-based microfluidic emulsification device for multiplexed, methylation-specific digital droplet PCR.</a> Analyst. 44 (22), 6541-6553 (2019).</li><li>Malic, 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=Polymer-based+microfluidic+chip+for+rapid+and+efficient+immunomagnetic+capture+and+release+of+Listeria+monocytogenes.">Polymer-based microfluidic chip for rapid and efficient immunomagnetic capture and release of Listeria monocytogenes.</a> Lab Chip. 15 (20), 3994-4007 (2015).</li><li>Malic, L., Morton, K., Clime, L., Veres, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=All-thermoplastic+nanoplasmonic+microfluidic+device+for+transmission+SPR+biosensing.">All-thermoplastic nanoplasmonic microfluidic device for transmission SPR biosensing.</a> Lab Chip. 13 (5), 798-810 (2013).</li></ol>

The presented experimental protocol and methods allow for in-house mdPCR using a fabricated TPE droplet generator, a thermal cycler, and fluorescence microscope. The fabricated device using soft TPE to TPE bonding affords hydrophobic surface properties that are uniform across all channel walls, such that the final device does not require any surface treatment for subsequent use as a droplet generator. This material has been routinely employed in point-of-care platforms that necessitate compatibility with high throughput ...

Analysis of white blood cells (WBCs) composition is among the most frequently requested laboratory tests in hematological diagnostics. Differential leukocyte count serves as an indicator for a spectrum of diseases including infection, inflammation, anemia, and leukemia, and is under investigation as an early prognostic biomarker for several other conditions as well. Gold standard in WBC subtyping involves immunostaining and/or flow cytometry both of which require costly, instability-prone fluorescent antibodies and are often highly dependent on operator proficiency in sample preparation. Moreover, this method is applicable to fresh blood samples only, such that the samples cannot be frozen for shipment or later analysis.
Epigenetic markers have recently emerged as powerful analytical tools for the study of phenotypic variations. Subsequently, human leukocyte populations have been shown to have cell-lineage DNA methylation patterns that allow for the precise characterization of WBC subsets. Subtyping based on epigenetic markers provides a promising alternative that does not depend on fresh blood sample collection or expensive antibodies and can be exploited as a biomarker for disease onset and susceptibility1,2,3,4,5.
Genome-wide studies have been performed for extensive mapping of methylated specific CG-rich regions in the genome (CpG islands) in leukocyte subtypes to identify candidate epigenetic markers specific to leukocyte subtypes. PCR protocols have been developed because of this reason for methylated gene regions, e.g., CD3Z and FOXP3, corresponding to CD3+ T-Cells and CD4+ CD25+ Regulatory T-Cells (T-Regs), respectively. Wiencke et al. have demonstrated the utility of duplex droplet PCR for epigenetic subtyping of T-Cells, yielding results that highly correlate with flow activated cell sorting (FACS) analysis6. This quantitative genetic analysis method relies on partitioning the template nucleic acid molecules and PCR reagents into thousands of discrete, volumetrically defined, sub-nanoliter sized droplets containing zero, one or more target nucleic acid copies, using water-in-oil emulsions enabled by microfluidics7,8. The PCR amplification is performed within each individual droplet and the endpoint fluorescence intensity of each droplet is measured, allowing absolute quantification of targets present in the sample. Droplet PCR has been established to be more precise, accurate, and technically simpler than standard qPCR, making it a more favorable DNA methylation-based method for clinical evaluation of T-Cells. Although a rapidly emerging subtyping methodology, multiplexed epigenetic analysis to probe for various methylated CpG regions simultaneously is lacking. This is necessary for routine leukocyte differential counts.
Herein, a thermoplastic elastomer (TPE) droplet microfluidic device is presented and employed for methylation-specific multiplex droplet PCR (mdPCR). The technology has been used to delineate specific leukocyte subtypes, CD3+ T-Cells and CD4+ CD25+ T-Regs, based on cell-lineage DNA methylation patterns, i.e., epigenetic variation of CD3Z and FOXP3 CpG regions, respectively. A detailed protocol for DNA extraction, bisulfite conversion and mdPCR is described in concert with a fabrication method for a TPE droplet generation device. Representative results of the method are compared to those of immunofluorescence staining highlighting the utility of the proposed approach.

<table>
	<tbody>
		<tr>
			<td>Bio-Rad, Mississauga, ON</td>
			<td>TFI0201</td>
			<td>PCR tube</td>
			<td></td>
		</tr>
		<tr>
			<td>RAN Biotechnologies, Beverly, MA</td>
			<td>008-FluoroSurfactant</td>
			<td>Fluoro-surfactant</td>
			<td></td>
		</tr>
		<tr>
			<td>Silicon Quest International, Santa Clara, CA</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Oxford Instruments, Abingdon, UK</td>
			<td></td>
			<td>EMCCD camera</td>
			<td></td>
		</tr>
		<tr>
			<td>Thermo Fisher Scientific, Waltham, MA</td>
			<td>MA5-16728</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Thermo Fisher Scientific, Waltham, MA</td>
			<td>22-8425-71</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>CellProfiler</td>
			<td></td>
			<td>Used for fluorescence image analysis</td>
			<td></td>
		</tr>
		<tr>
			<td>Nikon, Japan</td>
			<td></td>
			<td>10x objective</td>
			<td></td>
		</tr>
		<tr>
			<td>American Type Culture Collection (ATCC), Manassas, VA</td>
			<td>PCS-800-011</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Ram&#233;-Hart Instrument Co. (Netcong, NJ)</td>
			<td>p/n 200-U1</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Fisher, Canada</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Vitrocom, NJ, USA</td>
			<td>5015 and 5010</td>
			<td>Borosilicate capilary tube</td>
			<td></td>
		</tr>
		<tr>
			<td>(http://definetherain.org.uk/)</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Hamamatsu, Japan</td>
			<td>LC-L1V5</td>
			<td>DEL UV light source</td>
			<td></td>
		</tr>
		<tr>
			<td>Dolomite</td>
			<td>3200063</td>
			<td>Disposable fluidic tubing</td>
			<td></td>
		</tr>
		<tr>
			<td>Dolomite</td>
			<td>3200302</td>
			<td>Disposable fluidic tubing</td>
			<td></td>
		</tr>
		<tr>
			<td>IDT, Coralville, IA</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Nikon, Melville, NY</td>
			<td></td>
			<td>Upright light microscope</td>
			<td></td>
		</tr>
		<tr>
			<td>Cytec Industries, Woodland Park, NJ</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>EV Group, Sch&#228;rding, Austria</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Zymo Research, Irvine, CA</td>
			<td>D5030</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Photron, San Diego, CA</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>IDT, Coralville, IA</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Gersteltec, Pully, Switzerland</td>
			<td></td>
			<td>SU-8 photoresist</td>
			<td></td>
		</tr>
		<tr>
			<td>Fineline Imaging, Colorado Springs, CO</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Qiagen, Hilden, Germany</td>
			<td>203603</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Image J</td>
			<td></td>
			<td>Used to assess droplet diameter</td>
			<td></td>
		</tr>
		<tr>
			<td>Anachemia, Montreal, QC</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Excelitas, MA, USA</td>
			<td></td>
			<td>Broad-spectrum LED fluorescent lamp</td>
			<td></td>
		</tr>
		<tr>
			<td>Galenvs Sciences Inc., Montreal, QC</td>
			<td>DE1010</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Hexpol TPE, &#197;m&#229;l, Sweden</td>
			<td></td>
			<td>Thermoplastic elastomer (TPE)</td>
			<td></td>
		</tr>
		<tr>
			<td>Thermo Fisher Scientific, Waltham, MA</td>
			<td>13-400-518</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Nikon, Japan</td>
			<td></td>
			<td>Used for image acquisition</td>
			<td></td>
		</tr>
		<tr>
			<td>3M, St Paul, MN</td>
			<td></td>
			<td>Carrier Oil</td>
			<td></td>
		</tr>
		<tr>
			<td>Thermo Fisher Scientific, Waltham, MA</td>
			<td>R37605</td>
			<td>Blue fluorescent live cell stain (DAPI)</td>
			<td></td>
		</tr>
		<tr>
			<td>IDEX Health &#38; Science, Oak Harbor, WA</td>
			<td>P-881</td>
			<td>PEEK fittings</td>
			<td></td>
		</tr>
		<tr>
			<td>Sigma-Aldrich, Oakville, ON</td>
			<td>806552</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Dow Corning, Midland, MI</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>ThinkyUSA, CA, USA</td>
			<td>ARV 310</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Ihc world, Maryland, USA</td>
			<td>IW-125-0</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Zinsser NA, Northridge, CA</td>
			<td>2607808</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Cetoni GmbH, Korbussen, Germany</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Sigma-Aldrich, Oakville, ON</td>
			<td>484431</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Bio-Rad, Mississauga, ON</td>
			<td>1861096</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Hitachi High-Technologies, Mississauga, ON</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Nikon, Melville, NY</td>
			<td></td>
			<td>Inverted microscope</td>
			<td></td>
		</tr>
		<tr>
			<td>Nikon, Japan</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Loctite</td>
			<td>AA 352</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

methylation specific multiplex droplet pcr using polymer droplet generator device for hematological diagnostics

A multiplexed droplet PCR (mdPCR) workflow and detailed protocol for determining epigenetic-based white blood cell (WBC) differential count is described, along with a thermoplastic elastomer (TPE) microfluidic droplet generation device. Epigenetic markers are used for WBC&#160;subtyping which is of important prognostic value in different diseases. This is achieved through the quantification of DNA methylation patterns of specific CG-rich regions in the genome (CpG loci). In this paper, bisulfite-treated DNA from peripheral blood mononuclear cells (PBMCs) is encapsulated in droplets with mdPCR reagents including primers and hydrolysis fluorescent probes specific for CpG loci that correlate with WBC sub-populations. The multiplex approach allows for the interrogation of many CpG loci without the need for separate mdPCR reactions, enabling more accurate parametric determination of WBC sub-populations using epigenetic analysis of methylation sites. This precise quantification can be extended to different applications and highlights the benefits for clinical diagnosis and subsequent prognosis.

The TPE-based microfluidic droplet generator device was fabricated using the described protocol as shown in Figure 1. A transparency mask was used in photolithography to obtain silicon (Si) master. Soft lithography was performed to obtain an inverse PDMS replica of the Si master which was then used to fabricate the epoxy mold. Epoxy precursor was poured onto the PDMS and cured to crosslink and harden. This mold, representing the exact replica of the Si master was more resilient for subsequen...

Watch this Scientific Journal Video about Methylation Specific Multiplex Droplet PCR using Polymer Droplet Generator Device for Hematological Diagnostics at JoVE.com

Methylation Specific Multiplex Droplet PCR using Polymer Droplet Generator Device for Hematological Diagnostics

Epigenetic markers are used for white blood cell (WBC) subtyping through the quantification of DNA methylation patterns. This protocol presents a multiplex droplet polymerase chain reaction (mdPCR) method using a thermoplastic elastomer (TPE)-based microfluidic device for droplet generation allowing for precise and multiplex methylation-specific target quantification of WBC differential counts.

A multiplexed droplet PCR (mdPCR) workflow and detailed protocol for determining epigenetic-based white blood cell (WBC) differential count is described, ...

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