Name: A Method of Targeted Cell Isolation via Glass Surface Functionalization (Video) | JoVE Journal
Uploaded: 2016-09-20T08:00:00.000+00:00
Duration: 10 min 40 s
Description: Learn a customizable glass surface functionalization method using desthiobiotin and streptavidin to gently capture and release specific cell types. This technique enables screening of biomarkers for tumor angiogenesis and drug resistance research.

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5 minutes

We would like to thank the American Cancer Society, Illinois Division (282802) and the National Science Foundation CBET (1512598) for funding support. We also would like to thank Dr. Dianwen Zhang from the University of Illinois Beckman Institute for microscopy training. Finally, we would like to thank Jared Weddell, Stacie Chen, and Spencer Mamer for insightful discussions.

1. Cleaning the Glass Surface and Preparing Reagents
<ol>
	<li>Place a glass surface in an oxygen plasma machine for 5 min at 50% power to clean it.</li>
	<li>Prepare 2.5 ml 2% reconstituted (3-aminopropyl) triethoxysilane (APTES) solution, by adding 50 &#181;l of APTES and 2.45 ml of ethanol in a conical tube.</li>
</ol>
2. APTES and DSB Functionalization
<ol>
	<li>Add APTES solution to the surfaces. Pipette 150 &#181;l per well for 8 well plates. Pipette 100 &#181;l per well for 24 well plates. Pipette 1.1 ml for 60 x 15 mm glass dishes. Cover the surfaces to prevent evaporation and uneven distribution of APTES solution. Place the surfaces on a platform shaker for 50 min at room temperature, which creates an even distribution of the APTES layer. 
	NOTE: APTES is an aminosilane that forms the first layer of the surface. If using a different surface, heuristically determine the volume of solution needed to cover the surface.</li>
	<li>Select the temperature for the oven, while the surfaces are on the shaker: Heat to 55 &#176;C for 2 hr for the 8 well plates and 24 well plates. Heat glass only dishes to 90 &#176;C for 1 hr.</li>
	<li>Rinse the surfaces with ethanol.
	<ol>
		<li>Administer the amount of ethanol required by referencing based on the surface used. Add 150 &#181;l ethanol to each well for 8 well plates. Add 125 &#181;l ethanol to each well for 24 well plates. Add 1.1 ml ethanol for glass dishes.</li>
		<li>Rinse the surface by discharging and drawing the liquid from a fixed point such as the corner of the well. Hold the pipette at approximately a 70&#176; angle so the tip is not directly pointed into the surface. Rinse twice more using ethanol. 
		NOTE: If any of the glass bottom well plates have any plastic in them, do not heat them above 65 &#176;C, as the plastic will begin to melt and warp.</li>
	</ol>
	</li>
	<li>Dry with 100% nitrogen gas dispensed from a tank. Place the surfaces in the oven.</li>
	<li>Prepare 2.5 ml of d-desthiobiotin (DSB) solution by combining 1.5 mg/ml DSB in 37.5 &#181;l of dimethyl sulfoxide (DMSO), and 5 mg/ml 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) in 2462.5 &#181;l of the 0.1 M 4-morpholinoethanesulfonic acid hydrate (MES) (pH 6) buffer. Then combine both solutions.</li>
	<li>Add 1 &#181;l of 2-&#946; mercaptoethanol, after 15 min, into the solution to quench the reaction between DSB and EDC. Remove hot APTES functionalized glass surfaces from the oven. Wait 5-10 min for the glass surfaces to cool.</li>
	<li>Add MES buffer the surface to rinse, using amounts based on the surface. Add 150 &#181;l MES buffer to each well for 8 well plates. Add 125 &#181;l MES buffer to each well for 24 well plates. Add 1.1 ml MES buffer for glass dishes.</li>
	<li>Rinse surface by discharging and drawing the liquid from a fixed point such as the corner of the well. Hold the pipette at approximately a 70&#176; angle so the tip is not directly pointed into the surface. Rinse twice more with MES buffer.</li>
	<li>Apply the DSB solution to the surfaces to allow them to incubate. Add 150 &#181;l DSB solution per well for 8 well plates. Add 100 &#181;l DSB solution per well for 24 well plates. Add 1.1 ml for glass dishes DSB solution.</li>
	<li>Place the DSB covered glass surfaces on a damp paper towel inside a Petri dish. Cover and incubate in a 4 &#176;C fridge for 18-24 hr.</li>
</ol>
3. Streptavidin Functionalization
<ol>
	<li>Rinse each glass surface three times with 1 ml of 1.0x Phosphate Buffered Saline (PBS). Rinse surface by discharging and drawing the liquid from a fixed point such as the corner of the well. Hold the pipette at approximately a 70&#176; angle so the tip is not directly pointed into the surface. Dilute the streptavidin (SAv) stock solution to 0.4 mg/ml (recommended). 
	NOTE: PBS is isotonic so it can be used as a medium for dilution and rinsing. PBS is used as a solvent for the SAv, and therefore, will not affect the ability of the SAv to bind to the surface.</li>
	<li>Apply 0.4 mg/ml of SAv solution evenly to the surfaces so that a thin layer of forms at the bottom of the glass, select the amount of solution based on surface. For 8 well plates, add 150 &#181;l 0.4 mg/ml SAv solution per well. For 24 well plates, add 100 &#181;l 0.4 mg/ml SAv solution per well. For glass dishes, add 1.1 ml 0.4 mg/ml SAv solution.</li>
	<li>Cover and move the plates to a 14 cm Petri dish to retain moisture. Incubate the Petri dish in refrigerator for 18-24 hr. 
	NOTE: It is essential to utilize consistent volumes of APTES, DSB, and SAv on each surface.</li>
	<li>Rinse each glass surface three times with 150&#160;&#181;l of PBS to remove SAv. Rinse surface by discharging and drawing the liquid from a fixed point such as the corner of the well. Hold the pipette at approximately a 70&#176; angle so the tip is not directly pointed into the surface.</li>
	<li>Wet a paper towel with de-ionized water and place the paper towel flat in 14 cm Petri dish surrounding the plates to retain moisture in the wells. Cover the Petri dish containing the wells. Incubate the Petri dish in a 4 &#176;C Biosafety level 1 (BSL-1) refrigerator until needed.</li>
</ol>
4. Cell Capture and Release
<ol>
	<li>Start with T175 flask(s) of cells intended for the experiment. Aspirate the media from flask(s). Wash out the remaining media with 5 ml of room temperature PBS. Aspirate PBS from the flask(s).</li>
	<li>Add 10 ml of non-enzymatic lifting agent, such as Cell Dissociation Solution, to the T-175 flask of cells. Put the flask in the incubator for 6 min to allow for lifting of the cells from the flask.</li>
	<li>After 6 min, add 10 ml of cold Hank&#39;s Balanced Salt Solution (HBSS; See List of Materials) to inactivate the lifting agent. Take out 20 &#181;l of cells to count number of cells in solution using a hemacytometer. 
	NOTE: Depending on the functionalized surfaces used in the capture experiment, the number of cells needed varies. For functionalized 8 well plates, use 300,000 cells per well. For functionalized glass dishes, use 1.1 million cells. For functionalized 24 well plates, 125,000 cells are recommended. More information on cell counting is found in the Supplement.</li>
	<li>Repeat steps 4.1- 4.3 for another flask of cells, if fewer cells are present than needed for the experiment. Combine cell suspensions and recount cells to get total number of cells in solution.</li>
	<li>Spin down cell suspension in a centrifuge at 500 x g for 5 min at 4 &#176;C to get a pellet of concentrated cells. Find the appropriate amount of HBSS to add to the cell suspension to get a concentration of 1 x 106 cells per ml, then aspirate the supernatant from the spun down cells, and add the calculated volume. This volume can be calculated using the equations in the Supplement.</li>
	<li>Pipette up and down (triturate) to resuspend the cells in solution and reduce cellular clumping in solution that may reduce antibody binding. Split the cellular solution into separate control and experimental solutions. View Supplemental File for components and calculations.</li>
	<li>Add the biotinylated antibodies to the respective cell solutions as described in the Supplemental File. Incubate for 30 min at 4 &#176;C on an end-over-end mixer. 
	NOTE: For MCF7GFP cells, 0.5 mg/ml hIgG or 0.5 mg/ml HLA-ABC antibodies are recommended. For RAW macrophages, 1 mg/ml mCD11b are recommended at half the volume to account for the dilution differences. For Human Umbilical Vein Endothelial Cells (HUVECs), 0.5 mg/ml hCD31 is recommended.</li>
	<li>Wash the functionalized glass surface with HBSS. For this experiment, an 8 well plate is advised.
	<ol>
		<li>Add 150 &#181;l HBSS to each well for 8 well plates. Rinse twice more using HBSS. Rinse surface by discharging and drawing the liquid from a fixed point such as the corner of the well. Hold the pipette at approximately a 70&#176; angle so the tip is not directly pointed into the surface. Keep cold at 4 &#176;C.</li>
	</ol>
	</li>
	<li>Add cell solutions to the wells and wait 45 min for the cells to incubate on ice on the shaker. Make the solution of biotin in sterile HBSS by using calculated volumes as described in the Supplement.</li>
	<li>Remove the cell solution from the glass wells by using HBSS.
	<ol>
		<li>Gently pipette 150 &#181;l HBSS into each well. Then pipette out the HBSS. Rinse surface by discharging and drawing the liquid from a fixed point such as the corner of the well. Hold the pipette at approximately a 70&#176; angle so the tip is not directly pointed into the surface.</li>
		<li>Repeat two more times. After washing, add HBSS to the wells to keep the cells wet.</li>
	</ol>
	</li>
	<li>Add 150 &#181;l of 20 mM biotin solution to each respective release well, and then wait 20 min to allow for reaction.</li>
	<li>Recollect non-specifically bound cells by washing with HBSS as stated above, and then if using fluorescently labeled cells, proceed to fluorescence image the cells. Also image live cells in a flask (as a control, to compare with the cells in the well). If using green fluorescent protein (GFP) transfected cells, the excitation will be 470 nm, and the emission will be 515 nm.</li>
</ol>
5. Antibody Optimization: Antibody Titration
<ol>
	<li>Begin by lifting the cells from the T75 or T175 flask as explained in step 4.1- 4.3. 
	NOTE: These volumes are calibrated for 24 well plates, but can be changed to suit any glass functionalized surfaces through heuristic testing. A representative antibody titration is shown in Figure 1.</li>
	<li>Count cells using the hemacytometer, and then spin down the cell solution in a conical tube at 500 x g for 5 min at 4 &#176;C. Reconstitute cells to 1 million cells per ml, using the calculations described in the Supplement.</li>
	<li>Split the 1 million cells per ml solution into six different solutions of 500 &#181;l in different centrifuge tubes for the antibody (Ab) solutions.
	<ol>
		<li>Dilute the antibody stock solution to 10 &#181;g/ml, 1 &#181;g/ml, 100 ng/ml, 10 ng/ml, 1 ng/ml. Create the controls by using 100 &#181;l of Stain Buffer (PBS + 1% sodium azide + 1% BSA), and 500 &#181;l of cells for the control with no Ab in it. For the blank control (No Ab and no cells), use a solution of 300 &#181;l PBS. 
		NOTE: CAUTION: Sodium azide is extremely toxic, explosive, and extreme care must be taken when using it. Please consult the material safety data sheet (MSDS) and use the appropriate safety equipment.</li>
	</ol>
	</li>
	<li>Combine and incubate the Ab solutions with the cell solutions in the end-over-end mixer at 4 &#176;C for 30 min. Rinse the functionalized 24 well plates with HBSS three times. Rinse the surface by discharging and drawing the liquid from a fixed point such as the corner of the well. Hold the pipette at approximately a 70&#176; angle so the tip is not directly pointed into the surface.</li>
	<li>Aliquot 125 &#181;l of each sample solution into the appropriate APTES, DSB, and SAv functionalized well. Incubate at 4 &#176;C or on ice for 45 min on the glass surface. Rinse the surface with HBSS three times to remove non-specifically attached cells. Rinse surface by discharging and drawing the liquid from a fixed point such as the corner of the well. Hold the pipette at approximately a 70&#176; angle so the tip is not directly pointed into the surface. Do NOT rinse the bottom row, as those are controls.</li>
	<li>Add 150 &#181;l of HBSS to each washed well, put the 24 well plates on ice, and then use a plate reader to measure fluorescence of GFP cells (Excitation 485 nm / Emission 528 nm) .</li>
</ol>
6. Cell Optimization: Cell Titration
<ol>
	<li>Lift the cells as mentioned in steps 4.1 -4.3.</li>
	<li>Count cells using a hemacytometer. Spin down cell solution in conical tube at 500 x g for 5 min at 4 &#176;C. Reconstitute cells to 1 million cells per ml. 
	NOTE: More information on the use of the hemacytometer can be found in the Supplement.</li>
	<li>Pipette 1.6 ml from the cell solution for the 1.6 million cells stock and place in a conical tube. Pipette 800 &#181;l of cells from the cell solution for the 800,000 cells stock and place in a conical tube. Pipette 80 &#181;l from the cell stock for the 80,000 cells stock and place in a conical tube. Pipette 8 &#181;l from the cell stock for 8,000 cells stock and place in a conical tube. 
	NOTE: Concentrations are given per 8 well plate measurements, replicate as needed. An example of plate output is shown in Figure 2.</li>
	<li>Take the four stock solutions and spin in a centrifuge at 500 x g for 5 min at 4 &#176;C. Re-suspend all stock solutions in 400 &#181;l of HBSS.</li>
	<li>Add 1.6 &#181;l of 100 ng/ml antibody to the 1.6 million cell stock, 0.8 &#181;l to the 800,000 cell stock, and 0.5 &#181;l to all other stocks. Incubate the antibody for 30 min in the end-over-end mixer for 30 min at 4 &#176;C. Wash the functionalized glass surface with HBSS three times. 
	NOTE: The functionalized 8 well plate is recommended for microscopy quantification, while the functionalized 24 well plate is recommended for plate reader quantification. Antibody concentration for 8,000 cell stock was not reduced to allow the limiting factor of the capture surface to not be the lack of antibodies in solution, but rather the capturing properties of the surface.</li>
	<li>Apply 150 &#181;l of the sample solutions to each well. Apply the 1.6 million cell stock to the first column of wells on the left. Apply the 800,000 cell stock to the second column from the left. Apply the 80,000 cell stock to the third column from the left. Finally apply the 8,000 cell stock to the last column. Incubate for 45 min at 4 &#176;C on the shaker. 
	NOTE: The 1.6 million cell stock serves as the highest concentration to be tested, and is double the amount of cells that is used typically in cell separation experiments (600,000 cells per well) The 800,000 cell stock serves as the control for the experiment as it is the typical cellular concentration that is used in cell separation experiments (3,000,000 cells per well). The 80,000 cell stock serves as a ten-fold dilution to test for lower concentrations for cellular capture (30,000 cells per well). The 8,000 cell stock serves as a hundred fold dilution to use as a test to check the lower limit of cellular separation (3,000 cells per well).</li>
	<li>Rinse with HBSS three times. Rinse surface by discharging and drawing the liquid from a fixed point such as the corner of the well. Hold the pipette at approximately a 70&#176; angle so the tip is not directly pointed into the surface. Collect all washes.</li>
	<li>Image the cells on a fluorescence microscope, if using 8 well plates, take pictures of each surface, and apply 150&#160;&#181;l biotin to each surface for one hour at 4 &#176;C on the shaker. After one hour, rinse biotin release wells with HBSS 3 times as before. Collect all washes from wells for counting with the hemocytometer and image the release wells.</li>
	<li>Apply 150&#160;&#181;l of 20 mM excess biotin solution to appropriate biotin release wells for 1 hr, if using 24 well plates, and then rinse those wells 3 times with HBSS. Quantitate 24 well plates using a plate reader. Use a hemacytometer to count cells from all collected well washes.</li>
</ol>
7. Image Analysis
Note: The FIJI software package (http://fiji.sc/Fiji) is recommended for image analysis. Initially, the images were converted into grayscale image, and then the brightness/contrast was altered to bring out the cells.
<ol>
	<li>Load up the image, and convert to grayscale by clicking the image tab then scrolling down to &#34;Type&#34; and then clicking &#34;8 bit&#34;.</li>
	<li>Increase the contrast of the image by clicking the image tab and then scrolling to &#34;Adjust&#34;. Click on &#34;Brightness and Contrast&#34;, and then use the scroll bars to make the cells stand out. If using fluorescence images, invert the images to make the cells more defined.</li>
	<li>Load a plugin onto ImageJ called ITCN (http://rsb.info.nih.gov/ij/plugins/itcn.html) to analyze the images.</li>
	<li>Open ITCN. When a dialog box appears that prompts the user with several parameters to estimate the size of the cell, set the minimum width of the cell of interest first. Click the &#34;Detect Dark Peaks&#34; option if the image is fluorescent and the cells are darkened.</li>
	<li>Set the threshold value at 2 initially, and then hit the &#34;Count&#34; button. A newly counted version of the picture will appear with red dots delineating where cells have been counted.</li>
	<li>Adjust the threshold and width parameter to get more accurate cellular data by defining the size of a &#34;cell&#34;. Note: The number of cells counted will be in a dialog box on the right. Changing parameters will give different number of cells counted.</li>
	<li>Continue to iterate through the threshold and width parameters until a good estimate is reached for the number of cells.</li>
</ol>

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<li>BD Biosciences. <a target="_blank" href="http://scholar.google.com/scholar?hl=en&safe=off&q=%22CD+Marker+Handbook%3A+Human+and+Mouse%22">CD Marker Handbook: Human and Mouse</a>. , at: 
 <a target="_blank" href="https://www.bdbiosciences.com/documents/cd_marker_handbook.pdf">https://www.bdbiosciences.com/documents/cd_marker_handbook.pdf</a> (2010).</li>
<li>Tanzeglock, T., Soos, M., Stephanopoulos, G., Morbidelli, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Induction+of+mammalian+cell+death+by+simple+shear+and+extensional+flows%5BTitle%5D)+AND+%22Biotechnol.+Bioeng%22%5BJournal%5D)">Induction of mammalian cell death by simple shear and extensional flows.</a> Biotechnol. Bioeng. 104 (2), 360-370 (2009).</li>
<li>Processing Blood. , at: 
 <a target="_blank" href="https://www.google.com/patents/US20140030238">https://www.google.com/patents/US20140030238</a> (2014).</li>
<li>Fukuda, S., Schmid-Schönbein, G. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Centrifugation+attenuates+the+fluid+shear+response+of+circulating+leukocytes%5BTitle%5D)+AND+%22J.+Leukoc.+Biol%22%5BJournal%5D)">Centrifugation attenuates the fluid shear response of circulating leukocytes.</a> J. Leukoc. Biol. 72 (July), 133-139 (2002).</li>
<li>dela Paz, N. G., Walshe, T. E., Leach, L. L., Saint-Geniez, M., D'Amore, P. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Role+of+shear-stress-induced+VEGF+expression+in+endothelial+cell+survival%5BTitle%5D)+AND+%22J.+Cell+Sci%22%5BJournal%5D)">Role of shear-stress-induced VEGF expression in endothelial cell survival.</a> J. Cell Sci. 125 (Pt 4), 831-843 (2012).</li>
<li>Allard, W. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Tumor+Cells+Circulate+in+the+Peripheral+Blood+of+All+Major+Carcinomas+but+not+in+Healthy+Subjects+or+Patients+With+Nonmalignant+Diseases+Tumor+Cells+Circulate+in+the+Peripheral+Blood+of+All+Major+Carcinomas+but+not+in+Healthy+Subjects+or+Patients+With+Nonmalignant+diseases.%26%2334%5BTitle%5D)+AND+%22Clinical+Cancer+Research%22%5BJournal%5D)">Tumor Cells Circulate in the Peripheral Blood of All Major Carcinomas but not in Healthy Subjects or Patients With Nonmalignant Diseases Tumor Cells Circulate in the Peripheral Blood of All Major Carcinomas but not in Healthy Subjects or Patients With Nonmalignant diseases.&#34.</a> Clinical Cancer Research. 10, 6897-6904 (2005).</li>
<li>Nagrath, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Isolation+of+rare+circulating+tumour+cells+in+cancer+patients+by+microchip+technology%5BTitle%5D)+AND+%22Nature%22%5BJournal%5D)">Isolation of rare circulating tumour cells in cancer patients by microchip technology.</a> Nature. 450 (7173), 1235-1239 (2007).</li>
<li>Chen, S., Weddel, J., Gupta, P., Conard, G., Parkin, J., Imoukhuede, P. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((QFlow+Cytometer-Based+Receptoromic+Screening%3A+A+High-throughput+Quantification+Approach+Informing+Biomarker+Selection+and+Nanosensor%5BTitle%5D)+AND+%22Submiss%22%5BJournal%5D)">QFlow Cytometer-Based Receptoromic Screening: A High-throughput Quantification Approach Informing Biomarker Selection and Nanosensor.</a> Submiss. , (2016).</li>
<li>Vasa, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Number+and+migratory+activity+of+circulating+endothelial+progenitor+cells+inversely+correlate+with+risk+factors+for+coronary+artery+disease%5BTitle%5D)+AND+%22Circ.+Res%22%5BJournal%5D)">Number and migratory activity of circulating endothelial progenitor cells inversely correlate with risk factors for coronary artery disease.</a> Circ. Res. 89 (1), E1-E7 (2001).</li>
<li>Hirsch, J. D., Eslamizar, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Easily+reversible+desthiobiotin+binding+to+streptavidin%2C+avidin%2C+and+other+biotin-binding+proteins%3A+uses+for+protein+labeling%2C+detection%2C+and+isolation%5BTitle%5D)+AND+%22Anal.+Biochem%22%5BJournal%5D)">Easily reversible desthiobiotin binding to streptavidin, avidin, and other biotin-binding proteins: uses for protein labeling, detection, and isolation.</a> Anal. Biochem. 308 (2), 343-357 (2002).</li>
<li>Wilchek, M., Bayer, E. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Applications+of+Avidin-Biotin+Technology%3A+Literature+Survey%5BTitle%5D)+AND+%22Methods+Enzymol%22%5BJournal%5D)">Applications of Avidin-Biotin Technology: Literature Survey.</a> Methods Enzymol. 152 (1), 183-189 (1987).</li>
<li>Wu, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Immunofluorescent+labeling+of+cancer+marker+Her2+and+other+cellular+targets+with+semiconductor+quantum+dots%5BTitle%5D)+AND+%22Nat.+Biotechnol%22%5BJournal%5D)">Immunofluorescent labeling of cancer marker Her2 and other cellular targets with semiconductor quantum dots.</a> Nat. Biotechnol. 21 (1), 41-46 (2002).</li>
<li>Lee-Montiel, F. T., Imoukhuede, P. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Engineering+quantum+dot+calibration+standards+for+quantitative+fluorescent+profiling%5BTitle%5D)+AND+%22J.+Mater.+Chem.+B%22%5BJournal%5D)">Engineering quantum dot calibration standards for quantitative fluorescent profiling.</a> J. Mater. Chem. B. 1, 6434(2013).</li>
<li>Oligonucleotide-linked magnetic particles and uses thereof. , Available from: 
 <a target="_blank" href="http://www.google.com/patents/US5512439">http://www.google.com/patents/US5512439</a> (1996).</li>
<li>Naranbhai, V., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Impact+of+blood+processing+variations+on+natural+killer+cell+frequency%2C+activation%2C+chemokine+receptor+expression+and+function%5BTitle%5D)+AND+%22J.+Immunol.+Methods%22%5BJournal%5D)">Impact of blood processing variations on natural killer cell frequency, activation, chemokine receptor expression and function.</a> J. Immunol. Methods. 366 (1-2), 28-35 (2011).</li>
<li>Yadav, A. R., Sriram, R., Carter, J. A., Miller, B. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Comparative+study+of+solution-phase+and+vapor-phase+deposition+of+aminosilanes+on+silicon+dioxide+surfaces%5BTitle%5D)+AND+%22Mater.+Sci.+Eng.+C%22%5BJournal%5D)">Comparative study of solution-phase and vapor-phase deposition of aminosilanes on silicon dioxide surfaces.</a> Mater. Sci. Eng. C. 35 (1), 283-290 (2014).</li>
</ol>

The authors have nothing to disclose.

Improvements in cell isolation techniques furthers scientific studies in structure-function relationships in neuroscience18, stem cell programming in regenerative biology, and angiogenic signaling in vascular biology19. Indeed, primary cell culture20 (e.g., HUVECs) in vascular biology is primarily done through the use of cell isolation techniques. Cell isolation was also recently used for quantitative flow (qFlow) cytometry analysis of plasma membrane receptors3,14,15,19,21<...

Current bench-top cell separation approaches (e.g., fluorescence activated cell sorting1, laser capture micro-dissection2, immuno-magnetic bead separation1) can take several hours of preparation and sorting. These large time scales can affect physiological response and expression levels, resulting in analyses that are not representative of the physiological response3. Systems are needed that can rapidly and efficiently isolate specific cell types without disrupting cell-surface receptor-levels in order to improve cell isolation and enrichment for biomedical applications. Therefore, the rationale for our approach is to develop a gentle approach for cell isolation.
The &#34;lab on a chip&#34; concept offers the promise of orders of magnitude quicker (hours-to-minutes) cell isolation, and most frequently involves capturing cells onto a surface and releasing cells or intracellular contents through physical4,5 or chemical methods6. Although these approaches offer a few advantages such as identifying protein7,8 expression, identifying RNA expression9-11, or even providing cells for in vitro culture12,13, many of these techniques cannot be translated to diagnostics such as cell receptor profiling due to their non-physiological environments. Enzymatic lifting agents such as collagenases can also affect these receptor quantities14,15, meaning cell receptor quantification techniques that use these lifting agents will not generate accurate physiological data. Cellular lysis prevents differentiation between the native surface receptors, and those which were previously internalized16. This protocol describes a fast and gentle approach for cell isolation.

<table><tbody><tr><td>(3-Aminopropyl) triethoxysilane (APTES)</td><td>Acros Organics</td><td>919-30-2</td><td>Used to make 2% APTES solution</td></tr><tr><td>Plasma Cleaner Pico</td><td>Diener</td><td>Model 1</td><td>Cleans surfaces and allows for bonding of PDMS to glass</td></tr><tr><td>d-Desthiobiotin (DSB)</td><td>Sigma</td><td>D20655</td><td>Used as the releasing mechanism in the cellular capture surface.&amp;nbsp;</td></tr><tr><td>dimethyl sulfoxide (DMSO)</td><td>British Drug Houses (BDH)</td><td>BDH1115-1LP</td><td>Dissolves the DSB into solution</td></tr><tr><td>1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC)</td><td>Thermo-Scientific</td><td>5g: 22980&lt;br/&gt; 25g: 22981</td><td>Activates carboxylic acids and allows binding of proteins to glass surface.</td></tr><tr><td>uncoated 8-well culture slide</td><td>BD Falcon</td><td>Case of 24: 354118&lt;br/&gt; Case of 96: 354108</td><td>Used in cellular experiments involving Zeiss fluorescence microscope such as initial capture and release quantification experiments</td></tr><tr><td>Glass bottom 24-well plates</td><td>MatTek</td><td>P24G-0-13-F</td><td>Used in cellular experiments involving the plate reader such as antibody and cellular titration experiments</td></tr><tr><td>Mercaptoethanol</td><td>Science Lab</td><td>60-24-2</td><td>Used to quench reaction between EDC and DSB</td></tr><tr><td>4-Morpholinoethanesulfonic acid hydrate&lt;br/&gt; (MES Hydrate 99%)</td><td>Fisher Scientific</td><td>AC172590250</td><td>Used to make 0.1 M MES Buffer for use in EDC reaction</td></tr><tr><td>Precision Oven</td><td>Thermo Scientific</td><td>11-475-153</td><td>Used in curing of PDMS and APTES layer.</td></tr><tr><td>Titramax 1000 Shaker</td><td>Heidolph</td><td>13-889-420</td><td>Used to ensure even distribution of APTES on surfaces.</td></tr><tr><td>1x Streptavidin 5 mg [e7105-5mg]</td><td>Proteo Chem</td><td>9013-20-1</td><td>Biotin-binding protein. May cause irritation.</td></tr><tr><td>5 cm Glass Dish</td><td>Fisher Scientific</td><td>08748A</td><td>Used in HUVEC studies as well as future profiling studies.</td></tr><tr><td>14 cm Petri Dish with Cover</td><td>Sigma-Aldrich</td><td>Z717231</td><td>Used to hold samples being functionalized and transport them.</td></tr><tr><td>MCF7-GFP cells</td><td>Cell Biolabs</td><td>AKR211</td><td>Stored in liquid nitrogen</td></tr><tr><td>RAW264.7 mouse macrophages</td><td>ATCC</td><td>TIB-71</td><td>Gifted to us from Smith lab at the University of Illinois. Stored in liquid nitrogen.</td></tr><tr><td>TrypLE</td><td>Life Technologies</td><td>12605036</td><td>Stored in 100 ml at room temperature</td></tr><tr><td>Dulbecco&amp;rsquo;s modified Eagle medium</td><td>Cell Media Facility at School of Chemical Sciences at UIUC</td><td>50003PC</td><td>Supplier: Corning</td></tr><tr><td>Nonessential amino acids</td><td>Cell Media Facility at School of Chemical Sciences at UIUC</td><td>25-025-CI</td><td>Already added into DMEM by facility. Supplier: Corning.</td></tr><tr><td>Cell scraper</td><td>Fisher Scientific</td><td>12-565-58</td><td>Small 23 cm 50 pack</td></tr><tr><td>Cell Dissociation Solution</td><td>Corning</td><td>MT-25-056CI</td><td>Used to lift cells non-enzymatically for the use in cell experiments</td></tr><tr><td>Hemacytometer</td><td>Hausser</td><td>02-671-54</td><td>Used to count cells for quantification of cell solutions and capture and release effectivity.</td></tr><tr><td>Biotin</td><td>Amresco</td><td>58-85-5</td><td>Used to release cells from surface.</td></tr><tr><td>HBSS</td><td>Created from Recipe</td><td>N/A</td><td>Used to keep cells alive in suspension as well as wash surfaces of non-specific binding. Adapted from Cold Spring Harbor Protocols: In 500&amp;nbsp;ml, use 4&amp;nbsp;g NaCl, 0.2&amp;nbsp;g KCl, 0.0402&amp;nbsp;g Na&lt;sub&gt;2&lt;/sub&gt;PO&lt;sub&gt;4&lt;/sub&gt;&amp;#8226;7H&lt;sub&gt;2&lt;/sub&gt;O, 0.03&amp;nbsp;g KH&lt;sub&gt;2&lt;/sub&gt;PO&lt;sub&gt;4&lt;/sub&gt; and 0.5&amp;nbsp;g glucose. Add DI water to get to&amp;nbsp;500 ml, filter, and then refrigerate.</td></tr><tr><td>HLA-ABC Antibody</td><td>BioLegend</td><td>311402</td><td>Antibody used to capture MCF7gfp cells</td></tr><tr><td>hIgG Antibody</td><td>BioLegend</td><td>HP6017</td><td>Antibody used to capture MCF7gfp cells</td></tr><tr><td>MCF7 GFP cells</td><td>Cell Biolabs</td><td>AKR-211</td><td>Luminal Breast Cancer line that has been transfected with green fluorescent protein.</td></tr><tr><td>Assorted Conicals</td><td>Thermo-Scientific</td><td>15mL: 12-565-268</td><td>50/15 ml plastic conicals for storing solutions and aliquots.</td></tr><tr><td>Mini-Tube Rotators (End over End Mixer)</td><td>Fisher Scientific</td><td>05-450-127</td><td>Used to incubate antibody and mix other cellular solutions in order to mix</td></tr><tr><td>Axiovert 200M (Fluorescence Microscope)</td><td>Zeiss</td><td>N/A</td><td>Zeiss Axiovert 200 M inverted florescence microscope.</td></tr><tr><td>Zeba Desalting columns</td><td>Thermo-Scientific</td><td>PI-87770</td><td>Used to purify newly biotinylated antibodies after the use of the Biotinylation Kit. Instructions provided at: http://www.funakoshi.co.jp/data/datasheet/PCC/89894.pdf</td></tr><tr><td>EZ Link Sulfo NHS Low Weight Biotinylation Kit</td><td>Thermo- Scientific</td><td></td><td>Used to biotinylate antibodies to allow them to integrate with the capture surface</td></tr><tr><td>Plate Reader</td><td>BioTek</td><td>Synergy HTX Multimode Reader</td><td>Used to quantitatively measure fluorescent intensity in the titration experiments.</td></tr></tbody></table>

a method of targeted cell isolation via glass surface functionalization

A Method of Targeted Cell Isolation via Glass Surface Functionalization

One of the limiting factors to the adoption and advancement of personalized medicine is the inability to develop diagnostic tools to probe individual nuances in expression from patient to patient. Current methodologies that try to separate cells to fill this niche result in disruption of physiological expression, making the separation technique useless as a diagnostic tool. In this protocol, we describe the functionalization and optimization of a surface for the cellular capture and release. This functionalized surface integrates biotinylated antibodies with a glass surface functionalized with an aminosilane (APTES), desthiobiotin and streptavidin. Cell release is facilitated through the introduction of biotin, allowing the recollection and purification of cells captured by the surface. This release is done through the targeting of the secondary moiety desthiobiotin, which results in a much more gentle release paradigm. This reduction in harsh reagents and shear forces reduces changes in cellular expression. The functionalized surface captures up to 80% of cells in a single cell mixture and has demonstrated 50% capture in a dual-cell mixture. Applications of this technology to xenografts and cancer separation studies are investigated. Quantification techniques for surface verification such as plate reader and ImageJ analyses are described as well.

Using this protocol we show cell capture (Figure 3A) and cell release (Figure 3C) of MCF7GFP cells as well as live cell controls (Figure 4). We quantified the cell capture as 60% and 80% were released (Figure 3C). When we extended this approach to a mixture of RAW 264.7 macrophages and MCF7GFP cells, 50% of RAW macrophages were captured (Fig. 3D) and 80% of RAW macrophages were release with 20 mM biotin (...

This protocol describes customizable surface functionalization of the desthiobiotin, streptavidin, and APTES system in order to isolate specific cell types of interest. In addition, this manuscript covers the applications, optimization, and verification of this process.

One of the limiting factors to the adoption and advancement of personalized medicine is the inability to develop diagnostic tools to probe individual ...

The overall goal of this glass surface functionalization process is to allow for the gentle capture and release of cells of interest. This method can help answer key questions in the field of tumor angiogenesis, enabling screening of cell biomarkers that indicate drug resistance. The main advantage of this technique is that it is completely customizable, for virtually any cell type of interest.As long as there is an antibody specific to the cell type, the surface can be adapted for its capture. Though this method can provide insight into cancer angiogenesis, it may also be applied to other diseases as purified samples are necessary for the development of more personalized treatment regimens. We first had the idea for this method when we were trying to develop a reversible release mechanism for capturing cells, using the interaction between desthiobiotin and the adivin family.After cleaning a glass surface in an oxygen plasma machine for five minutes according to the text protocol, prepare 2.5 milliliters of 2%reconstituted 3-Aminopropyl triethoxysilane, or APTES solution, by combining 50 microliters of APTES and 2.45 milliliters of ethanol in a conical tube. Pipette the APTES solution onto the glass surfaces, then cover the surfaces and place them on a platform shaker at room temperature for 50 minutes to evenly distribute the APTES layer. In the meantime, preheat the oven to 55 degrees Celsius for the eight-and 24-well plates, or 90 degrees Celsius for the glass dishes.After removing the plates from the shaker, use ethanol to rinse the glass surfaces according to the text protocol. With 100%nitrogen gas, dry the surfaces. Then place the eight-and 24-well plates in the oven for two hours, or the glass dishes in the oven for one hour.Next, prepare 2.5 milliliters of d-Desthiobiotin, or DSB solution, by mixing 1.5 milligrams per milliliter of DSB in 37.5 microliters of DMSO, and adding five milligrams per milliliter of EDC to 2, 462.5 microliters of 0.1 Molar MES buffer, pH 6. Then combine the two solutions. After 15 minutes, add one microliter of BME to quench the reaction between DSB and EDC.Remove the hot APTES functionalized glass surfaces from the oven, and allow them to cool for five to 10 minutes. Add MES buffer to the glass surfaces to rinse them by holding the pipette at a 70 degree angle so that the tip is not directly pointed at the surface. Then discharge and draw the buffer from a fixed point, such as the corner of the well.Then, use the MES buffer to rinse two more times. Apply DSB solution to the glass surfaces. Transfer them to a damp paper towel inside a Petri dish, cover the dish, and incubate in the fridge for 18 to 24 hours.After the incubation at four degrees Celsius, use PBS to rinse each glass surface three times, as demonstrated earlier in this video. Then, dilute Streptavidin, or SAV stock solution, to 0.4 milligrams per milliliter, and evenly apply it to the glass surfaces so that a thin layer forms. After incubating the glass for 18 to 24 hours, use 150 microliters of PBS to rinse each surface three times.Then wet a paper towel with deionized water, and place it flat in a 14 centimeter Petri dish surrounding the plates to retain moisture in the wells. Cover the Petri dish with the glass surfaces, and place it in a four degrees Celsius biosafety Level 1 fridge until needed. To carry out cell capture, aspirate the medium from T175 flasks of cells.Then use PBS to rinse the cells and aspirate the buffer. Add 10 milliliters of non-enzymatic lifting agent, such as Cell Dissociation Solution, to the flask. Then incubate at 37 degrees Celsius for six minutes.After six minutes, add 10 milliliters of cold HBSS to dilute the lifting agent. Then pipette 20 microliters of the cells and use a hemocytometer to count them. Centrifuge the cell suspension at 500 x g, in four degrees Celsius, for five minutes.And use HBSS to resuspend the cells to one times 10 to the sixth cells per milliliter. Pipette up and down to resuspend the cells in solution, and reduce cellular clumping that may reduce antibody binding. Then, split the cellular suspension into separate control and experimental solutions.Add the biotinylated antibodies to the respective cells solutions and incubate on an end-over-end mixer at four degrees Celsius for 30 minutes. Use 150 microliters of HBSS to wash the functionalized glass in eight-well plates three times, as demonstrated earlier in the video. Add the cell solution to the wells, and incubate on ice on the shaker for 45 minutes.In the meantime, prepare a 20 millimolar solution of biotin in sterile HBSS. Then, after the incubation, gently use 150 microliters of HBSS to rinse the cell solution from the glass. After repeating the rinse two more times, add 150 microliters of the biotin solution to each respective release well, and incubate for 20 minutes to allow the reaction to proceed.Recollect nonspecifically bound cells by using HBSS to wash the cells. Then, proceed to fluorescence imaging and analysis according to the text protocol. Include images of live cells in a flask as a control.In this experiment, MCF7GFP cells were exposed to the functionalized surface. 60%of the cells were captured using the HLA-ABC antibody. Upon exposure to 20 millimolar biotin, 80%of the captured cells were released.As shown here when the MCF7GFP cells were mixed with RAW 264.7 cells, 50%of the RAW macrophages were captured, and the addition of 20 micromolar biotin subsequently released 80%of the captured RAW cells. This figure illustrates that the positive control RAW macrophages exhibit no fluorescence activity. However, the negative control MCF7GFP cells are positive for GFP fluorescence.Because excess antibody can decrease cell capture, the antibody concentration was optimized by titrating from zero to 10, 000 nanograms per milliliter of HLA antibody. The results showed that the ideal antibody concentration was between 100 and 1, 000 nanograms per milliliter. In addition, cell optimization experiments determined that the ideal concentration of cells that can be captured is between one times 10 to the fifth, and one times 10 to the sixth cells, since quantities below that number are lower than the background.Once mastered, this technique can be done in three days, with less than six hours of experimental time, not including the overnight incubations. While attempting this procedure, it's important to remember to collect the cell washes during the experiments, as they can give vital information about the effectiveness of the surface. Following this procedure, other methods like flow cytometry can be performed in order to answer additional questions, like what receptor expression levels the cells of interest may have.After its development, surface functionalization has paved the way for researchers in the field of biomaterials to explore biosafe integration of materials, such as, implants in patients for a variety of diseases and injuries. After watching this video, you should have a good understanding of how to surface functionalize glass surfaces to capture and release cells of interest, allowing for downstream analysis. Don't forget that working with live cells in sodium azide can be extremely hazardous, and precautions such as proper training, PPE, and disposal, should always be taken while performing this procedure.

a-method-targeted-cell-isolation-via-glass-surface

Research

JoVE Journal

Cancer Research

In this article we describe how we obtain FRET traces from individual DNA molecules immobilized to a surface using an automated scanning confocal microscope.

Automated System for Single Molecule Fluorescence Measurements of Surface-immobilized Biomolecules

Source: Fattahi, N., et al. Photodegradable Hydrogel Interfaces for Bacteria Screening, Selection, and Isolation. J. Vis. Exp. (2021).This video demonstrates the extraction of bacterial colonies from a photodegradable hydrogel using UV light. A specific colony is selected, and a patterned light exposure is designed to initiate localized hydrogel degradation. After adjusting light intensity and duration, the UV light is applied, releasing the colony. The colony is then aspirated through tubing...

Targeted Bacterial Colony Isolation Using Light-Patterned Hydrogel Degradation

In this video, we demonstrate the isolation of EpCAM-expressing epithelial cancer cells from peripheral blood samples. The technique involves the use of a medical-grade wire functionalized with EpCAM antibodies to capture the target cells. The captured cells are then subsequently extracted into a buffer solution.

Functionalized Wire-based Target Cell Isolation: An Ex Vivo Technique to Isolate Cancer Cells from Spiked Peripheral Blood

Contactless dielectrophoresis (cDEP) achieves sorting and enrichment of particles via their intrinsic dielectric properties. Fluidic electrode channels replace metallic electrodes traditional to DEP, suiting cDEP to non-damaging sterile characterization and sorting of biological particles. We demonstrate how to prepare a cDEP microdevice and conduct cell characterization and sorting experiments.

Label-free Isolation and Enrichment of Cells Through Contactless Dielectrophoresis

Traditional techniques for fabricating polyacrylamide (PA) gels containing fluorescent probes involve sandwiching a gel between an adherent surface and a glass slide. Here, we show that coating this slide with poly-D-lysine (PDL) and fluorescent probes localizes the probes to within 1.6 µm from the gel surface.

A Novel Method for Localizing Reporter Fluorescent Beads Near the Cell Culture Surface for Traction Force Microscopy

Here, we present a protocol for isolating and culturing single cells with a microfluidic platform, which utilizes a new microwell design concept to allow for high-efficiency single cell isolation and long-term clonal culture.

A Microfluidic Platform for High-throughput Single-cell Isolation and Culture

This protocol is to recover and prepare rare target cells from a mixture with non-target background cells for molecular genetic characterization at the single-cell level. DNA quality is equal to non-treated single cells and allows for single-cell application (both screening based and targeted analysis).

Target Cell Pre-enrichment and Whole Genome Amplification for Single Cell Downstream Characterization

We describe a simple lithographic procedure for the immobilization of gene-length DNA molecules on a surface, which can be used to perform cell-free gene expression experiments on biochips.

Functional Surface-immobilization of Genes Using Multistep Strand Displacement Lithography

The use of photodegradable hydrogels to isolate bacterial cells by utilizing a high-resolution light pattering tool is reported. Essential experimental procedures, results, and advantages of the process are reviewed. The method enables rapid and inexpensive isolation of targeted bacteria showing rare or unique functions from heterogeneous communities or populations.

Photodegradable Hydrogel Interfaces for Bacteria Screening, Selection, and Isolation

We adapted a permeable microporous membrane insert to mimic the tumor microenvironment (TME). The model consists of a mixed cell culture, allows simplified generation of highly enriched individual cell populations without using fluorescent tagging or cell sorting, and permits studying intercellular communication within the TME under normal or stress conditions.

A Mimic of the Tumor Microenvironment: A Simple Method for Generating Enriched Cell Populations and Investigating Intercellular Communication

Learn a customizable glass surface functionalization method using desthiobiotin and streptavidin to gently capture and release specific cell types. This technique enables screening of biomarkers for tumor angiogenesis and drug resistance research.

A Method of Targeted Cell Isolation via Glass Surface Functionalization

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