This work was supported by NIH/NIAID (R21AI119042) as well as NIH U24 Sample Sparing assay program (U24-AI118656).

The sample collection was approved by the University of Pittsburgh Institutional Review Board (IRB# PRO16060443, PRO10110387). All experiments are performed under a biosafety cabinet with the proper personal protective equipment.
1. Device Fabrication and Soft Lithography
NOTE: Standard soft lithography techniques15,16 were used to create the polydimethylsiloxane (PDMS) microchannel.
<ol>
	<li>Mix the PDMS...

<ol>
	<li>Hamid, Q., 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=Methods+of+sputum+processing+for+cell+counts,+immunocytochemistry+and+in+situ+hybridisation.">Methods of sputum processing for cell counts, immunocytochemistry and in situ hybridisation.</a> European Respiratory Journal. 20 (Supplement 37), 19S-23S (2002).</li><li>van Overveld, F. 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=Effects+of+homogenization+of+induced+sputum+by+dithiothreitol+on+polymorphonuclear+cells.">Effects of homogenization of induced sputum by dithiothreitol on polymorphonuclear cells.</a> J Physiol Pharmacol. 56, 143-154 (2005).</li><li>Qiu, D., Tan, W. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dithiothreitol+has+a+dose-response+effect+on+cell+surface+antigen+expression.">Dithiothreitol has a dose-response effect on cell surface antigen expression.</a> J Allergy Clin Immunol. 103 (5 Pt 1), 873-876 (1999).</li><li>Usher, L. R., 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=Induction+of+Neutrophil+Apoptosis+by+the+Pseudomonas+aeruginosa+Exotoxin+Pyocyanin:+A+Potential+Mechanism+of+Persistent+Infection.">Induction of Neutrophil Apoptosis by the Pseudomonas aeruginosa Exotoxin Pyocyanin: A Potential Mechanism of Persistent Infection.</a> The Journal of Immunology. 168 (4), 1861-1868 (2002).</li><li>Di Carlo, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inertial+microfluidics.">Inertial microfluidics.</a> Lab Chip. 9 (21), 3038-3046 (2009).</li><li>Martel, J. M., Toner, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inertial+focusing+dynamics+in+spiral+microchannels.">Inertial focusing dynamics in spiral microchannels.</a> Phys Fluids. 24 (3), 32001 (2012).</li><li>Zhang, 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=Fundamentals+and+applications+of+inertial+microfluidics:+a+review.">Fundamentals and applications of inertial microfluidics: a review.</a> Lab Chip. 16 (1), 10-34 (2016).</li><li>Hou, H. W., Bhattacharyya, R. P., Hung, D. T., Han, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+detection+and+drug-resistance+profiling+of+bacteremias+using+inertial+microfluidics.">Direct detection and drug-resistance profiling of bacteremias using inertial microfluidics.</a> Lab Chip. 15 (10), 2297-2307 (2015).</li><li>Warkiani, M. 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=Ultra-fast,+label-free+isolation+of+circulating+tumor+cells+from+blood+using+spiral+microfluidics.">Ultra-fast, label-free isolation of circulating tumor cells from blood using spiral microfluidics.</a> Nat Protoc. 11 (1), 134-148 (2016).</li><li>Warkiani, M. E., Tay, A. K., Guan, G., Han, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Membrane-less+microfiltration+using+inertial+microfluidics.">Membrane-less microfiltration using inertial microfluidics.</a> Sci Rep. 5, 11018 (2015).</li><li>Warkiani, M. E., Wu, L., Tay, A. K., Han, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Large-Volume+Microfluidic+Cell+Sorting+for+Biomedical+Applications.">Large-Volume Microfluidic Cell Sorting for Biomedical Applications.</a> Annu Rev Biomed Eng. 17, 1-34 (2015).</li><li>Kwon, 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=Microfluidic+Cell+Retention+Device+for+Perfusion+of+Mammalian+Suspension+Culture.">Microfluidic Cell Retention Device for Perfusion of Mammalian Suspension Culture.</a> Sci Rep. 7 (1), 6703 (2017).</li><li>Wu, L., Guan, G., Hou, H. W., Bhagat, A. A., Han, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Separation+of+leukocytes+from+blood+using+spiral+channel+with+trapezoid+cross-section.">Separation of leukocytes from blood using spiral channel with trapezoid cross-section.</a> Anal Chem. 84 (21), 9324-9331 (2012).</li><li>Guan, 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=Spiral+microchannel+with+rectangular+and+trapezoidal+cross-sections+for+size+based+particle+separation.">Spiral microchannel with rectangular and trapezoidal cross-sections for size based particle separation.</a> Sci Rep. 3, 1475 (2013).</li><li>Kotz, K., Cheng, X., Toner, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=PDMS+Device+Fabrication+and+Surface+Modification.">PDMS Device Fabrication and Surface Modification.</a> J Vis Exp. (8), e319 (2007).</li><li>Duffy, D. C., McDonald, J. C., Schueller, O. J. A., 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=Rapid+Prototyping+of+Microfluidic+Systems+in+Poly(dimethylsiloxane).">Rapid Prototyping of Microfluidic Systems in Poly(dimethylsiloxane).</a> Analytical Chemistry. 70 (23), 4974-4984 (1998).</li><li>Ryu, 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=Patient-Derived+Airway+Secretion+Dissociation+Technique+To+Isolate+and+Concentrate+Immune+Cells+Using+Closed-Loop+Inertial+Microfluidics.">Patient-Derived Airway Secretion Dissociation Technique To Isolate and Concentrate Immune Cells Using Closed-Loop Inertial Microfluidics.</a> Anal Chem. 89 (10), 5549-5556 (2017).</li><li>Mach, A. J., Di Carlo, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Continuous+scalable+blood+filtration+device+using+inertial+microfluidics.">Continuous scalable blood filtration device using inertial microfluidics.</a> Biotechnol Bioeng. 107 (2), 302-311 (2010).</li><li>Di Carlo, D., Irimia, D., Tompkins, R. G., Toner, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Continuous+inertial+focusing,+ordering,+and+separation+of+particles+in+microchannels.">Continuous inertial focusing, ordering, and separation of particles in microchannels.</a> Proc Natl Acad Sci U S A. 104 (48), 18892-18897 (2007).</li><li>Xiang, 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=Fundamentals+of+elasto-inertial+particle+focusing+in+curved+microfluidic+channels.">Fundamentals of elasto-inertial particle focusing in curved microfluidic channels.</a> Lab Chip. 16 (14), 2626-2635 (2016).</li><li>Lotvall, 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=Asthma+endotypes:+a+new+approach+to+classification+of+disease+entities+within+the+asthma+syndrome.">Asthma endotypes: a new approach to classification of disease entities within the asthma syndrome.</a> J Allergy Clin Immunol. 127 (2), 355-360 (2011).</li><li>Houston, 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=Sputum+neutrophils+in+cystic+fibrosis+patients+display+a+reduced+respiratory+burst.">Sputum neutrophils in cystic fibrosis patients display a reduced respiratory burst.</a> J Cyst Fibros. 12 (4), 352-362 (2013).</li><li>Janoff, A., Scherer, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mediators+of+inflammation+in+leukocyte+lysosomes.+IX.+Elastinolytic+activity+in+granules+of+human+polymorphonuclear+leukocytes.">Mediators of inflammation in leukocyte lysosomes. IX. Elastinolytic activity in granules of human polymorphonuclear leukocytes.</a> J Exp Med. 128 (5), 1137-1155 (1968).</li><li>Kawabata, K., Hagio, T., Matsuoka, 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+neutrophil+elastase+in+acute+lung+injury.">The role of neutrophil elastase in acute lung injury.</a> Eur J Pharmacol. 451 (1), 1-10 (2002).</li><li>Rubin, B. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Plastic+Bronchitis.">Plastic Bronchitis.</a> Clin Chest Med. 37 (3), 405-408 (2016).</li><li>Kokot, K., Teschner, M., Schaefer, R. M., Heidland, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stimulation+and+inhibition+of+elastase+release+from+human+neutrophils+dependent+on+the+calcium+messenger+system.">Stimulation and inhibition of elastase release from human neutrophils dependent on the calcium messenger system.</a> Miner Electrolyte Metab. 13 (2), 133-140 (1987).</li></ol>

In inertial microfluidics, particle and cells localize at a certain lateral position in a micro-channel based on their size5,18,19,20. Due to the combined effect of the Dean drag force and the inertial lift force in the curved microchannel, large particles or neutrophils (&#62;10 &#181;m) are located inside the channel and small particles, mucus aggregates, and debris smaller than 6 &#181;m are...

Since cells are encapsulated in a large amount of mucus in airway secretions, the functional assessment of leukocytes by an in vitro assay has been hindered. Dithiothreitol (DTT) is the most common lysis buffer to dissociate and homogenize the sputum for cytological analysis and detection of mediators while providing tolerable viability of isolated cells1,2. However, DTT can interfere with surface-bound antigens of airway neutrophils, resulting in the disruption of neutrophil function such as elastase and myeloperoxidase (MPO) release2,3.Therefore, few studies of human airway neutrophil function have been conducted with peripheral blood neutrophils, which may not reveal the physiological characteristics of pulmonary4. Meanwhile, inertial microfluidics has made advances in isolating cells from various patient biomatrices5,6.The equilibrium between inertial lift forces and Dean drag aligns the particle/cell according to their size, which allows label-free particle separation7. Our group previously introduced a sample preparation method for circulating tumor cells8,9, pathogens in blood8, cells from a suspension culture10,11,12, and polymorphonuclear leukocytes (PMNs) from blood13,14.
Here, we introduce a protocol to prepare immune cells from a patient&#39;s airway secretions using closed-loop inertial microfluidics for a downstream in vitro assay, such as the neutrophil elastase (NE) assay. This method provides both high concentration and recovery, especially when there is a significant overlap in the lateral direction of the cell/particle from which the cell/particle-of-interest is to be removed, which is commonly observed in clinical samples. By recirculating the Inner wall (IW)-focused large particles or cells back to the input sample tube, the particle or cell-of-interest concentrates in the original reservoir, while background fluids with small mucin aggregates pass through the waste reservoir. Despite the heterogeneous fluidic properties of clinical samples, the proposed method recovers consistently above 95% of neutrophils from airway secretion samples that are diluted 1,000-fold with a clean saline solution (~1 mL). By contrast, the lysis method presents a wide range of PMNs recovery rates depending on the sample condition. The proposed protocol captures leukocytes in a label-free manner with no physical or chemical disruption, which provides the possibility to harvest delicate cells from clinically challenging biometrics with minimally invasive procedures.

<table>
	<tbody>
		<tr>
			<td>PDMS precursor</td>
			<td>Dow corning</td>
			<td>184 SIL ELAST KIT 3.9KG</td>
			<td>10:1 ratio of base and curing agent</td>
		</tr>
		<tr>
			<td>VWR gravity convection oven</td>
			<td>VWR</td>
			<td>414005-128</td>
			<td>PDMS precursor to be cured in 90 deg.</td>
		</tr>
		<tr>
			<td>100mm petri dish</td>
			<td>VWR</td>
			<td>89000-324</td>
			<td>Fabrication of PDMS Supporting layer</td>
		</tr>
		<tr>
			<td>Harris Uni-core puncher</td>
			<td>Sigma-aldrich</td>
			<td>WHAWB100076</td>
			<td>2mm diameter or other depending on the tubing size</td>
		</tr>
		<tr>
			<td>Air plasma machine</td>
			<td>Femto Science</td>
			<td>Cute</td>
			<td>Surface plasma treatment for PDMS device to bottom base.</td>
		</tr>
		<tr>
			<td>2&#8221; x 3&#8221; glass slide</td>
			<td>TED PELLA, INC.</td>
			<td>2195</td>
			<td>To support PDMS device</td>
		</tr>
		<tr>
			<td>Masterflex spooled platinum-cured silicone tubing, L/S 14</td>
			<td>Cole-Parmer</td>
			<td>EW-96410-14</td>
			<td>Tubing for microfluidics and peristlatic pump</td>
		</tr>
		<tr>
			<td>1/16 inch Luer connector, male</td>
			<td>Harvard apparatus</td>
			<td>PC2 72-1443</td>
			<td>Connector for fluid guide</td>
		</tr>
		<tr>
			<td>50mL Falcon tube</td>
			<td>Corning</td>
			<td>21008-940</td>
			<td>sample collection &#38; preparation</td>
		</tr>
		<tr>
			<td>Phosphate-Buffered Saline, 1X Without Calcium and Magnesium</td>
			<td>Corning</td>
			<td>45000-446&#160;</td>
			<td>Buffer solution to dilute sample</td>
		</tr>
		<tr>
			<td>Halyard Closed suction Catheter, Elbow, 14F/ channel 4.67mm</td>
			<td>HALYARD HEALTH</td>
			<td>22113</td>
			<td>Tracheal seceation suction catheter</td>
		</tr>
		<tr>
			<td>0.9% Sterile Normal saline, 10mL pre-filled syringe</td>
			<td>BD PosiFlush</td>
			<td>NHRIC: 8290-306547</td>
			<td>For tracheal seceation collection from the patients</td>
		</tr>
		<tr>
			<td>SecurTainer&#8482; III Specimen Containers, 20mL</td>
			<td>Simport</td>
			<td>1176R36</td>
			<td>Sterile sputum (airway secretion) collection container</td>
		</tr>
		<tr>
			<td>Syringe with Luer-Lok Tip, 10mL</td>
			<td>BD</td>
			<td>BD309604</td>
			<td>To pipette homogenize the mucus sample and reach the bottom of sample tube</td>
		</tr>
		<tr>
			<td>BD&#160; Blunt Fill Needle, with BD Luer-Lok&#160; Tip</td>
			<td>BD</td>
			<td></td>
			<td>To pipette homogenize the mucus sample and reach the bottom of sample tube</td>
		</tr>
		<tr>
			<td>40&#181;m nylon cell strainer&#160;</td>
			<td>Falcon</td>
			<td>21008-949</td>
			<td>To remove large chunk or blood clots, which can block the microfluidics access hole or the channel.</td>
		</tr>
		<tr>
			<td>Peristaltic pump (Masterflex L/S Digital Drive)</td>
			<td>Cole-Parmer</td>
			<td>HV-07522-30</td>
			<td>operation of microfluidics</td>
		</tr>
		<tr>
			<td>BD LSR II flow cytometer</td>
			<td>BD Bioscience</td>
			<td>LSR II flow cytometer</td>
			<td>Quantification of cell recovery ratio</td>
		</tr>
		<tr>
			<td>Fluorescein isothiocyanate (FITC)-conjugated mouse anti-human CD66b monoclonal antibody</td>
			<td>BD Bioscience</td>
			<td>561927</td>
			<td>Immunostaining of neutrophils for Flow cytometer analysis</td>
		</tr>
		<tr>
			<td>Allophycocyanin (APC)-conjugated mouse anti-human CD45 monoclonal antibody</td>
			<td>BD Bioscience</td>
			<td>561864</td>
			<td>Immunostaining of neutrophils for Flow cytometer analysis</td>
		</tr>
		<tr>
			<td>Plate reader</td>
			<td>Thermo Fisher scientific</td>
			<td>Varioskan</td>
			<td>Plate reader for neutrophil elastase assay, ex485/em525</td>
		</tr>
		<tr>
			<td>Neutrophil elastase assay kit</td>
			<td>Cayman Chemical</td>
			<td>600610</td>
			<td>Neutrophil functionality assessment</td>
		</tr>
		<tr>
			<td>Fluoresbrite YG Microspheres 10.0&#181;m</td>
			<td>PolyScience, Inc.</td>
			<td>18140-2</td>
			<td>Fluorescent particles to express white blood cell trajectory in microfluidics</td>
		</tr>
	</tbody>
</table>

label-free neutrophil enrichment from patient-derived airway secretion using closed-loop inertial microfluidics

Airway secretions contain a large number of immune-related cells, e.g., neutrophils, macrophages, and lymphocytes, which can be used as a major resource to evaluate a variety of pulmonary diseases, both for research and clinical purposes. However, due to the heterogeneous and viscous nature of patient mucus, there is currently no reliable dissociation method that does not damage the host immune cells in the patient airway secretion. In this research, we introduce a sample preparation method that uses inertial microfluidics for the patient&#39;s immune assessment. Regardless of the heterogeneous fluidic properties of the clinical samples, the proposed method recovers more than 95% of neutrophils from airway secretion samples that are diluted 1,000-fold with milliliters of clean saline. By recirculating the concentrated output stream to the initial sample reservoir, a high concentration, recovery, and purity of the immune cells are provided; recirculation is considered a trade-off to the single-run syringe-based operation of inertial microfluidics. The closed-loop operation of spiral microfluidics provides leukocytes without physical or chemical disturbance, as demonstrated by the phorbol 12-myristate 13-acetate (PMA)-induced elastase release of sorted neutrophils.

We achieved transparent immune-cell suspensions with both DTT mucolysis and microfluidics dissociation (Figure 3A). Microfluidics dissociation collected 4.40 x 105 PMNs on average (2.1 x 104 to 5.60 x 105 PMNs, n = 6) from airway secretion samples diluted 1,000-fold (50 mL total volume) in 1 mL of clean suspension. Compared to the initial diluent, 94.0% PMNs (CD66b+/CD45+) were recovered in a small volume...

Watch this Scientific Journal Video about Label-free Neutrophil Enrichment from Patient-derived Airway Secretion Using Closed-loop Inertial Microfluidics at JoVE.com

Label-free Neutrophil Enrichment from Patient-derived Airway Secretion Using Closed-loop Inertial Microfluidics

In this research, we demonstrate a label-free neutrophil separation method from clinical airway secretions using closed-loop operation of spiral inertial microfluidics. The proposed method would expand the clinical in vitro assays for various respiratory diseases.

Airway secretions contain a large number of immune-related cells, e.g., neutrophils, macrophages, and lymphocytes, which can be used as a major resource ...

This method can help answer key questions in the pulmonary diseases research such as pneumonia, asthma, cystic fibrosis, and chronic obstructive pulmonary disease. The main advantage of this technique is to isolate and enrich patient neutrophil from patient airway secretion without vertical chemical disturbance. Demonstrating the procedure will be Kyungyong, a PhD student from my laboratory.To start with, maintain a ratio of 10 to one and mix the PDMS precursor with the base and curing agent. Next, add 30 grams of the PDMS mixture on the micro machine aluminum mold. Then add another 20 grams of PDMS mixture on a 100 millimeter Petri dish.For the purpose of degas, put the mold and the Petri dish in the vacuum desiccator. After degassing, release the vacuum and place the mold and the Petri dish in an oven at 90 degrees Celsius for an hour. After one hour, remove the mold and the Petri dish from the oven and let it cool at room temperature for 10 minutes.Next, use a knife to cut the outline and punch the fluid access holes with two millimeter biopsy punch on the device. After punching the holes, secure a tape and adhere it to the channel side of the device and on the thick film of PDMS. Use forceps to peel the tape carefully to remove the dust.Then start treating the channel side of the device and the plain PDMS with air plasma. Then bond both the channel side and the plain PDMS with the prepared supporting layer of plain PDMS. Next, leave the chip on a glass slide with dimensions of 102 by 76 millimeters.Place the glass slide in an oven at 70 degrees Celsius for at least 30 minutes to increase the bond strength. Use a 10 milliliter syringe to collect one milliliter of airway secretion samples in nine milliliters of phosphate buffered saline. Then with the help of a blunt pipette, homogenize the mucus sample.Next, use a 40 micrometer nylon cell strainer to strain the diluent and remove large chunks of tissue or blood clots. After the straining is complete, put the sample on ice. Then add 50 milliliters of phosphate buffered saline to the 0.5 milliliter sample diluent to achieve a final concentration of 1, 000 times diluted sample.Use the fluid guide to assemble the PDMS chip in order to apply uniform flow to each of the four spiral micro channels. Next, use a male Luer connector with 1/16 inch diameter to connect to the inlet, the inner wall outlet, and the outer wall outlet ports of the fluid guide. Then connect the silicone tubing to the sample suspension.Next, connect the peristaltic pump to the inlet tubing. Place the outer wall outlet tubing in the waste reservoir. Then position the end of the inlet tubing and the inner wall outlet tubing in the sample reservoir.After positioning the tubing, leave a 50 milliliter tube filled with five milliliters of phosphate buffered saline without calcium and magnesium in the sample reservoir. Then in order to prime the device, start pumping at a flow rate of approximately one milliliter per minute. After placing the sample in the sample reservoir, switch on the peristaltic pump and set the flow rate at four milliliters per minute.After the sample volume reaches the desired volume of approximately one to two milliliters, stop the operation and disconnect the tubing. Clinical sample consisting of patient tracheal secretion is used for the microfluidic dissociation method in order to obtain the PMN rich population of cells. On subjecting the microfluidic dissociation method, highly purified CD45, CD66B plus rich PMN population of cells are obtained.Here, the samples obtained from two different patients represented as case one and two are subjected to microfluidic dissociation to obtain the resulting cell suspension. Next, on subjecting the patient airway secretion sample to microfluidics, 94%of PMN are recovered consistently from all six samples. On the other hand, subjecting the patient sample to DTT mucolysis method resulted in recovering only 53.5%of PMNs with wide variation among the samples.The neutrophils isolated by the microfluidics and DTT mucolytic methods are treated with PMA to trigger the neutrophil elastase release. Interestingly, patient samples subjected to microfluidics show intact functional cells with increased release of elastase by PMA stimulation. Whereas cells obtained after mucolytic dissociation show no significant increase in the elastase release from six different patient samples studied.This is due to a chemically disturbed neutrophil surface. Once mastered, this technique can be done in 50 minutes if it is performed properly. By providing a dissociation protocol to capture neutrophils from clinical airway secretions, the method presented in this study is expected to expand the scope of clinical research on respiratory diseases such as pneumonia, asthma, cystic fibrosis, and chronic obstructive pulmonary disease.The implications of this technique extend towards therapy of immune related pulmonary diseases such as asthma and chronic obstructive pulmonary disease because the proposed methods provides a way to capturing patient immune cell in noninvasive and label-free manner. Though this method can provide insight into respiratory research, it can also be applied to other patient biofluids with challenging biometrics such as nasal fluid, cervical fluid, and intestinal fluid. After watching this video, you should have a good understanding of how to separate neutrophils from patient airway secretion using close-looped spiral inertia microfluidics.Don't forget that working with clinical samples can be extremely hazardous. All experiments must be performed under a biosafety cabinet with the personal protective equipments.

label-free-neutrophil-enrichment-from-patient-derived-airway

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Immunology and Infection

Detection of Human Leukocyte Antigen Biomarkers in Breast Cancer Utilizing Label-free Biosensor Technology

According to the American Cancer Society, more than 200,000 women will be diagnosed with invasive breast cancer each year and approximately 40,000 will die from the disease. The human leukocyte antigen (HLA) class I samples peptides derived from proteasomal degradation of cellular proteins and presents these fragments on the cell surface for interrogation by circulating cytotoxic T lymphocytes (CTL). Generation of T-cell receptor mimic (TCRm) monoclonal antibodies (mAbs) which recognize breast cancer specific peptide/HLA-A*02:01 complexes such as those derived from macrophage migration inhibitory factor (MIF19-27) and NY-ESO-1157-165 enable detection and destruction of breast cancer cells in the absence of an effective anti-tumor CTL response. Intact class I HLA/peptide complexes are shed by breast cancer cells and represent potentially relevant cancer biomarkers. In this work, a breakthrough biomarker screening system for cancer diagnostics incorporating T-cell receptor mimic monoclonal antibodies combined with a novel, label-free biosensor utilizing guided-mode resonance (GMR) sensor technology is presented. Detection of shed MIF/HLA-A*02:01 complexes in MDA-MB-231 cell supernatants, spiked human serum, and patient plasma is demonstrated. The impact of this work could revolutionize personalized medicine through development of companion disease diagnostics for targeted immunotherapies.

Intact class I HLA/peptide complexes are shed by cancer cells, representing a potential relevant cancer biomarker. Utilizing label-free sensor technology and T-cell receptor mimicking monoclonal antibodies, detection of shed MIF/HLA-A*02:01 complexes in MDA-MB-231 cell supernatants, spiked human serum, and patient plasma is demonstrated, enabling development of a novel cancer diagnostic platform.

According to the American Cancer Society, more than 200,000 women will be diagnosed with invasive breast cancer each year and approximately 40,000 will ...

Intravital Imaging of Neutrophil Priming Using IL-1&#946; Promoter-driven DsRed Reporter Mice

Neutrophils are the most abundant leukocytes in human blood circulation and are quickly recruited to inflammatory sites. Priming is a critical event that enhances the phagocytic functionality of neutrophils. Although extensive studies have unveiled the existence and importance of neutrophil priming during infection and injury, means of visualizing this process in vivo have been unavailable. The protocol provided enables monitoring of the dynamic process of neutrophil priming in living animals by combining three methodologies: 1) DsRed reporter signal &#8212; used as a measure of priming 2) in vivo neutrophil labeling &#8212; achieved by injection of fluorescence-conjugated anti-lymphocyte antigen 6G (Ly6G) monoclonal antibody (mAb) and 3) intravital confocal imaging. Several critical steps are involved in this protocol: oxazolone-induced mouse ear skin inflammation, appropriate sedation of animals, repeated injections of anti-Ly6G mAb, and prevention of focus drift during imaging. Although a few limitations have been observed, such as the limit of continuous imaging time (~ 8 hr) in one mouse and the leakage of fluorescein isothiocyanate-dextran from blood vessels in the inflammatory state, this protocol provides a fundamental framework for intravital imaging of primed neutrophil behavior and function, which can easily be expanded to examination of other immune cells in mouse inflammation models.

Intravital Imaging of Neutrophil Priming Using IL-1&amp;#946; Promoter-driven DsRed Reporter Mice

This current protocol employs fluorescent reporters, in vivo labeling, and intravital imaging techniques to enable monitoring of the dynamic process of neutrophil priming in living animals.

Neutrophils are the most abundant leukocytes in human blood circulation and are quickly recruited to inflammatory sites. Priming is a critical event that ...

Imaging the Neutrophil Phagosome and Cytoplasm Using a Ratiometric pH Indicator

Neutrophils are crucial to host innate defense and, consequently, constitute an important area of medical research. The phagosome, the intracellular compartment where the killing and digestion of engulfed particles take place, is the main arena for neutrophil pathogen killing that requires tight regulation. Phagosomal pH is one aspect that is carefully controlled, in turn regulating antimicrobial protease activity. Many fluorescent pH-sensitive dyes have been used to visualize the phagosomal environment. S-1 has several advantages over other pH-sensitive dyes, including its dual emission spectra, its resistance to photo-bleaching, and its high pKa. Using this method, we have demonstrated that the neutrophil phagosome is unusually alkaline in comparison to other phagocytes. By using different biochemical conjugations of the dye, the phagosome can be delineated from the cytoplasm so that changes in the size and shape of the phagosome can be assessed. This allows for further monitoring of ionic movement.

This manuscript describes a simple method to measure the phagosomal pH and area as well as the cytoplasmic pH of human and mouse neutrophils using the ratiometric indicator seminaphthorhodafluor (SNARF)-1, or S-1. This is achieved using live-cell confocal fluorescence microscopy and image analysis.

Neutrophils are crucial to host innate defense and, consequently, constitute an important area of medical research. The phagosome, the intracellular ...

Label-Free Identification of Lymphocyte Subtypes Using Three-Dimensional Quantitative Phase Imaging and Machine Learning

We describe here a protocol for the label-free identification of lymphocyte subtypes using quantitative phase imaging and machine learning. Identification of lymphocyte subtypes is important for the study of immunology as well as diagnosis and treatment of various diseases. Currently, standard methods for classifying lymphocyte types rely on labeling specific membrane proteins via antigen-antibody reactions. However, these labeling techniques carry the potential risks of altering cellular functions. The protocol described here overcomes these challenges by exploiting intrinsic optical contrasts measured by 3D quantitative phase imaging and a machine learning algorithm. Measurement of 3D refractive index (RI) tomograms of lymphocytes provides quantitative information about 3D morphology and phenotypes of individual cells. The biophysical parameters extracted from the measured 3D RI tomograms are then quantitatively analyzed with a machine learning algorithm, enabling label-free identification of lymphocyte types at a single-cell level. We measure the 3D RI tomograms of B, CD4+ T, and CD8+ T lymphocytes and identified their cell types with over 80% accuracy. In this protocol, we describe the detailed steps for lymphocyte isolation, 3D quantitative phase imaging, and machine learning for identifying lymphocyte types.

We describe a protocol for the label-free identification of lymphocyte subtypes using quantitative phase imaging and a machine learning algorithm. Measurements of 3D refractive index tomograms of lymphocytes present 3D morphological and biochemical information for individual cells, which is then analyzed with a machine-learning algorithm for identification of cell types.

We describe here a protocol for the label-free identification of lymphocyte subtypes using quantitative phase imaging and machine learning. Identification ...

Automated Image-Based Quantification of Neutrophil Extracellular Traps Using NETQUANT

Neutrophil extracellular traps (NETs) are web-like antimicrobial structures consisting of DNA and granule derived antimicrobial proteins. Immunofluorescence microscopy and image-based quantification methods remain important tools to quantitate neutrophil extracellular trap formation. However, there are key limitations to the immunofluorescence-based methods that are currently available for quantifying NETs. Manual methods of image-based NET quantification are often subjective, prone to error and tedious for users, especially non-experienced users. Also, presently available software options for quantification are either semi-automatic or require training prior to operation. Here, we demonstrate the implementation of an automated immunofluorescence-based image quantification method to evaluate NET formation called NETQUANT. The software is easy to use and has a user-friendly graphical user interface (GUI). It considers biologically relevant parameters such as an increase in the surface area and DNA:NET marker protein ratio, and nuclear deformation to define NET formation. Furthermore, this tool is built as a freely available app, and allows for single-cell resolution quantification and analysis.

Here, we present a protocol for generating neutrophil extracellular traps (NETs) and operating NETQUANT, a fully automatic software option for quantification of NETs in immunofluorescence images.

Neutrophil extracellular traps (NETs) are web-like antimicrobial structures consisting of DNA and granule derived antimicrobial proteins. ...

Identification of Neutrophil Extracellular Traps in Paraffin-Embedded Feline Arterial Thrombi using Immunofluorescence Microscopy

Neutrophil extracellular traps (NETs), composed of cell-free DNA (cfDNA) and proteins like histones and neutrophil elastase (NE), are released by neutrophils in response to systemic inflammation or pathogens. Although NETs have previously been shown to augment clot formation and inhibit fibrinolysis in humans and dogs, the role of NETs in cats with cardiogenic arterial thromboembolism (CATE), a life-threatening complication secondary to hypertrophic cardiomyopathy, is unknown. A standardized method to identify and quantify NETs in cardiogenic arterial thrombi in cats will advance our understanding of their pathological role in CATE. Here, we describe a technique to identify NETs in formaldehyde-fixed and paraffin-embedded thrombi within the aortic bifurcation, extracted during necropsy. Following deparaffinization with xylene, aortic sections underwent indirect heat-induced antigen retrieval. Sections were then blocked, permeabilized, and ex vivo NETs were identified by colocalization of cell-free DNA (cfDNA), citrullinated histone H3 (citH3), and neutrophil elastase (NE) using immunofluorescence microscopy. To optimize the immunodetection of NETs in thrombi, autofluorescence of tissue elements was limited by using an autofluorescence quenching process prior to microscopy. This technique could be a useful tool to study NETs and thrombosis in other species and offers new insights into the pathophysiology of this complex condition.

We describe a method to identify neutrophil extracellular traps (NETs) in formaldehyde-fixed and paraffin-embedded feline cardiogenic arterial thrombi using heat-induced antigen retrieval and a double immunolabeling protocol.

Neutrophil extracellular traps (NETs), composed of cell-free DNA (cfDNA) and proteins like histones and neutrophil elastase (NE), are released by ...

Label-Free Quantitative Proteomics Workflow for Discovery-Driven Host-Pathogen Interactions

The technological achievements of mass spectrometry (MS)-based quantitative proteomics opens many undiscovered avenues for analyzing an organism&#8217;s global proteome under varying conditions. This powerful strategy applied to the interactions of microbial pathogens with the desired host comprehensively characterizes both perspectives towards infection. Herein, the workflow describes label-free quantification (LFQ) of the infectome of Cryptococcus neoformans, a fungal facultative intracellular pathogen that is the causative agent of the deadly disease cryptococcosis, in the presence of immortalized macrophage cells. The protocol details the proper protein preparation techniques for both pathogen and mammalian cells within a single experiment, resulting in appropriate peptide submission for liquid-chromatography (LC)-MS/MS analysis. The high throughput generic nature of LFQ allows a wide dynamic range of protein identification and quantification, as well as transferability to any host-pathogen infection setting, maintaining extreme sensitivity. The method is optimized to catalogue extensive, unbiased protein abundance profiles of a pathogen within infection-mimicking conditions. Specifically, the method demonstrated here provides essential information on C. neoformans pathogenesis, such as protein production necessary for virulence and identifies critical host proteins responding to microbial invasion.

Here, we present a protocol to profile the interplay between host and pathogen during infection by mass spectrometry-based proteomics. This protocol uses label-free quantification to measure changes in protein abundance of both host (e.g., macrophages) and pathogen (e.g., Cryptococcus neoformans) in a single experiment.

The technological achievements of mass spectrometry (MS)-based quantitative proteomics opens many undiscovered avenues for analyzing an organism&#8217;s ...

Quantifying Myeloperoxidase-DNA and Neutrophil Elastase-DNA Complexes from Neutrophil Extracellular Traps by Using a Modified Sandwich ELISA

Certain stimuli, such as microorganisms, cause neutrophils to release neutrophil extracellular traps (NETs), which are basically web-like structures composed of DNA with granule proteins, such as myeloperoxidase (MPO) and neutrophil elastase (NE), and cytoplasmic and cytoskeletal proteins. Although interest in NETs has increased recently, no sensitive, reliable assay method is available for measuring NETs in clinical settings. This article describes a modified sandwich enzyme-linked immunosorbent assay to quantitatively measure two components of circulating NETs, MPO-DNA and NE-DNA complexes, which are specific components of NETs and are released into the extracellular space as breakdown products of NETs. The assay uses specific monoclonal antibodies for MPO or NE as the capture antibodies and a DNA-specific detection antibody. MPO or NE binds to one site of the capture antibody during the initial incubation of samples containing MPO-DNA or NE-DNA complexes. This assay shows good linearity and high inter-assay and intra-assay precision. We used it in 16 patients with COVID-19 with accompanying acute respiratory distress syndrome and found that the plasma concentrations of MPO-DNA and NE-DNA were significantly higher than in the plasma obtained from healthy controls. This detection assay is a reliable, highly sensitive, and useful method for investigating the characteristics of NETs in human plasma and culture supernatants.

We present a protocol for a modified sandwich enzyme-linked immunosorbent assay technique to quantitatively measure two components of neutrophil extracellular trap remnants, myeloperoxidase conjugated-DNA and neutrophil elastase conjugated-DNA complexes,derived from activated neutrophils.

Certain stimuli, such as microorganisms, cause neutrophils to release neutrophil extracellular traps (NETs), which are basically web-like structures ...

Quantifying NET Formation Using Dual-Dye Live Cell Analysis

Real-Time High Throughput Technique to Quantify Neutrophil Extracellular Traps Formation in Human Neutrophils

Neutrophils are myeloid-lineage cells that form a crucial part of the innate immune system. The past decade has revealed additional key roles that neutrophils play in the pathogenesis of cancer, autoimmune diseases, and various acute and chronic inflammatory conditions by contributing to the initiation and perpetuation of immune dysregulation through multiple mechanisms, including the formation of neutrophil extracellular traps (NETs), which are structures crucial in antimicrobial defense. Limitations in techniques to quantify NET formation in an unbiased, reproducible, and efficient way have restricted our ability to further understand the role of neutrophils in health and diseases. We describe an automated, real-time, high-throughput method to quantify neutrophils undergoing NET formation using a live cell imaging platform coupled with a membrane permeability-dependent dual-dye approach using two different DNA dyes to image intracellular and extracellular DNA. This methodology is able to help assess neutrophil physiology and test molecules that can target NET formation.

Author Spotlight: Quantifying Neutrophil Extracellular Traps in Disease and Drug Screening Using Dual-Color Live-Cell Imaging

We present an automated high-throughput method to quantify neutrophil extracellular traps (NETs) utilizing the live cell analysis system, coupled with a membrane permeability-dependent dual-dye approach.