This work was supported by the NSF Major Research Instrument mechanism under grant numbers 1626093 and 1919583.

NOTE: All medium preparation and cell culture techniques are carried out under aseptic conditions using a biosafety cabinet with laminar flow. All culture incubation steps described are carried out using an incubator designed to maintain an atmosphere of 37 &#176;C, 5% CO2, and 95% humidity.
1. Cell culture
<ol>
	<li>Preparation of growth medium
	<ol>
		<li>For MSC and LADMAC, add 50 mL of FBS and 5 mL of 100x antibiotic/antimycotic mix to 500 mL of high glucose DMEM.</li>
		<li>For the M&#934;, add 50 mL of FBS, 100 mL of LADMAC condition medium (prepared following the steps of section 1.2), and 5 mL of 100x antibiotic mix to 500 mL of high glucose DMEM. 
		&#8203;NOTE: LADMAC cells produce colony-stimulating factor (CSF-1) necessary to support the growth of the M&#934; cells.</li>
	</ol>
	</li>
	<li>Preparation of LADMAC conditioned medium
	<ol>
		<li>To seed LADMAC cells from frozen stock, add 19 mL of growth medium from section 1.1 in each of the five T75 cm2 cell-culture treated flasks and place in the cell culture incubator for 15 min to equilibrate to 37 &#176;C.</li>
		<li>Meanwhile, quick thaw one aliquot of 106 frozen cells by incubating in a 37 &#176;C water bath for 2-3 min or until it gets thawed. Add the cells to 9 mL of fresh MSC growth medium in a 15 mL or 50 mL sterile conical tube and centrifuge at 125 x g in a swinging bucket rotor for 5 min.</li>
		<li>Aspirate or decant the supernatant, add 5 mL of fresh growth medium, and gently pipette up and down to resuspend the cell pellet.</li>
		<li>Add 1 mL of the cell suspension to each of the five T75 cm2 flasks using a sterile serological pipette and place them&#160;in the cell culture incubator.</li>
		<li>Every 2-3 days, add an additional 10 mL of medium over a 7-10-day period. Then, collect the cells and the supernatant into sterile 50 mL conical tubes using a sterile serological pipette and centrifuge at 125 x g for 5 min.</li>
		<li>Separate the supernatant from the cell pellet and sterile filter the supernatant using a 0.2 &#181;m sterile single-use vacuum filter unit.
		<ol>
			<li>Remove the aspirator assembly from the package and connect using vacuum tubing to the aspirator pump. Pour the supernatant into the top compartment and replace the cover. Turn on the aspirator pump to filter into the bottom compartment.</li>
			<li>Prepare aliquots by pipetting into 50 mL sterile conical tubes and store at -20 &#176;C.</li>
		</ol>
		</li>
		<li>To freeze the cell pellet, resuspend in freezing medium at 106 cell/mL, place in a freezing container, and then place them in a -80 &#176;C freezer. After 24 h, transfer to LN2 storage.</li>
	</ol>
	</li>
	<li>Propagate cells in preparation for co-culture
	<ol>
		<li>To seed MSC and M&#934; cells from the frozen stock, equilibrate 9 mL of appropriate growth medium prepared in section 1.1 in each of the four 100 mm cell culture treated dishes for each cell type and place in the cell culture incubator for 15 min.</li>
		<li>Meanwhile, quick thaw the aliquots of 106 frozen cells by incubating them in a 37 &#176;C water bath for 2-3 min or until just thawed. Then, add the thawed MSC cells to 9 mL of fresh MSC growth medium and add the thawed M&#934; cells to 9 mL fresh M&#934; growth medium in 15 or 50 mL sterile conical tubes and centrifuge at 125 x g in swinging bucket rotor for 5 min.</li>
		<li>Aspirate or decant the supernatant and resuspend each pellet in 4 mL of the appropriate fresh growth medium by gently pipetting up and down. Add 1 mL of the cell suspension to each of the four 100 mm dishes for each cell type that have been equilibrated in step 1.3.1.</li>
		<li>Return the dishes with cells to the incubator. Change the medium every 2-3 days until 70%-80% confluent.</li>
	</ol>
	</li>
</ol>
2. Seed MSC in experimental dishes, Day 1
NOTE: Prior to seeding the MSC, design the experimental 96-well plate layout for fluorescent spectrophotometry and the chamber slide for dynamic imaging. For the 96-well plate, flank experimental wells with wells containing cells but do not use them in the assay. Mark at least four wells to be used for the reagent blank (RBL). See Table 1 for an example 96-well template and Table 2 for an example of a 4-well chamber slide template. Black or white 96-well plates with clear bottoms are recommended. A 1.5 mm borosilicate glass chamber slide is optimal, but the number of chambers can be adjusted dependent on the study design. A summary flow chart of the methods that follow is included in Figure 2.
<ol>
	<li>At 70%-80% confluency, aspirate the growth medium from the cultures in 100 mm dishes and add 5 mL of PBS to isolate the MSC.</li>
	<li>Aspirate the PBS, add 2 mL of 0.05% trypsin/EDTA, and place it in the culture incubator for 3-5 min.</li>
	<li>After 3 min, check the cell detachment using an inverted microscope. If the cells are detached, continue to the next step; if not, continue incubation for another 1-2 min. Do not incubate longer than 5-6 min.</li>
	<li>Add 5 mL of fresh growth medium to the dish with the detached cells. Rinse the dish using the trypsin/medium mixture and collect cells into a clean, sterile 50 mL conical tube using a sterile serological pipette.</li>
	<li>Centrifuge for 5 min at 125 x g. Aspirate the supernatant and resuspend the cell pellet in 10 mL of fresh growth medium by gently pipetting up and down.</li>
	<li>To count the cells, add 10 &#181;L of the cell suspension to 30 &#181;L of 0.4% trypan blue solution in a 1.5 mL microcentrifuge tube. Then, pipette 10 &#181;L of the mixture under the coverslip of a hemocytometer counting chamber.</li>
	<li>Using an inverted or bright field microscope, with the 10x objective, count the unstained (viable) cells in four of the 1 mm2 squares. Calculate the cell number using the formula: cells/mL = cell count/# 1 mm2 squares x dilution factor x 104. 
	NOTE: For this example, the number of 1 mm2 squares counted is four, and the dilution factor is 4.</li>
	<li>Use the equation C1V1 = C2V2 to calculate for and prepare a 1 x 105 cell/mL suspension. Prepare 1 mL of cell/mL suspension for every column of the 96-well plate to be filled and 0.75 mL for every chamber of the 4-well chamber slide to be filled according to the plate design. 
	NOTE: C1 = cell count, V1 = what is being calculated, C2 = 1 x 105, V2 = 5.50 mL.</li>
	<li>Determine V1, subtract it from the desired 5.50 mL of the total volume to determine the volume of the fresh medium needed to prepare the suspension. Add the volume of cells (V1) from the original suspension to the volume of fresh medium for a total of 5.50 mL with 1 x 105 cells/mL.</li>
	<li>Add 100 &#181;L of 1 x 105 cell/mL suspension to each well of the 96-well plate according to the plate design using a multichannel micropipettor and 530 &#181;L to each of the wells of the chamber slide using a micropipette according to the plate design. Incubate overnight. 
	NOTE: For this experiment, MSC&#160;are plated in columns 1, 2, 3, and 6 of the 96-well plate (Table 1) and wells 1 and 2 of the 4-well chamber slide (Table 2). Therefore, at least 5.50 mL of a 1 x 105 cell/mL suspension is prepared. M&#934; at 80% confluence are treated with inflammatory mediators the same day the MSC&#160;are seeded in the experimental plates.</li>
</ol>
3. Activate the M&#934; with IFN-&#947;, Day 1
<ol>
	<li>Prepare the activation medium and IFN-&#947; stock.
	<ol>
		<li>For 200 mL of activation medium, add 40 mg of BSA to 200 mL of serum-free high glucose DMEM and sterile filter using a 0.2 &#181;m sterile single-use vacuum filter unit.</li>
		<li>To prepare 0.1% BSA/PBS, add 20 mg of BSA to 20 mL of PBS. Vortex to dissolve. Use a 0.2 &#181;m sterile syringe filter to filter into a clean, sterile 50 mL conical tube.</li>
		<li>Add 1 mL of the sterile 0.1% BSA/PBS solution to 100 &#181;g of lyophilized IFN-&#947; to achieve a 100 &#181;g/mL of stock solution. Store in 50 &#181;L aliquots at -20 &#176;C.</li>
	</ol>
	</li>
	<li>Activate the M&#934; with IFN-&#947;
	<ol>
		<li>Add 2.5 &#181;L of 100 &#181;g/mL of IFN-&#947; stock for every 1 mL of the medium needed. For every 100 mm dish to be activated, prepare 10 mL of activation medium containing IFN-&#947; at a concentration of 250 ng/mL.</li>
		<li>Aspirate the growth medium from the M&#934; cultures and replace it with 5 mL of the activation medium without IFN- &#947; to rinse.</li>
		<li>Aspirate the medium used for rinsing and replace it with 10 mL of IFN- &#947; supplemented activation medium for the experimental dish and with 10 mL of non-supplemented activation medium for the control. Incubate the cultures for 16-24 h.</li>
	</ol>
	</li>
</ol>
4. Isolate the M&#934; and prepare the co-cultures, Day 2
<ol>
	<li>Remove the activation medium from the M&#934; cells and replace it with 5 mL of fresh growth medium. Scrape gently with a cell lifter and collect the cells into a 50 mL conical tube.</li>
	<li>Count the cells using trypan blue exclusion and hemocytometry as described for MSC in, steps 2.6-2.7.</li>
	<li>Using the equation in steps 2.8-2.9, prepare two separate suspensions of 2 x 105 cells/mL, one with cells from the control and one with cells from the treated M&#934; cultures. 
	NOTE: Prepare 1 mL of cell/mL suspension for every column of the 96-well plate to be filled and 0.75 mL for every chamber of the 4-well chamber slide to be filled according to the plate design.</li>
	<li>Gently aspirate the medium from the experimental wells of the 96-well plate containing MSC. Using a multichannel micropipette, add 100 &#181;L of the treated and the control M&#934; cell suspensions in the appropriate experimental wells with and without MSC according to the plate design. Incubate overnight.</li>
	<li>Gently aspirate the medium from the 4-well chamber slide containing MSC, and, using a micropipette, add 530 &#181;L of M&#934; cell suspension to the appropriate wells according to the design. Incubate overnight.</li>
</ol>
5. Phagocytosis assay, kinetic fluorescent 96-well plate read, Day 3
<ol>
	<li>Set the assay parameters
	<ol>
		<li>On the day of the assay, turn on the fluorescent plate reader and computer-set the temperature on the system to 37 &#176;C.</li>
		<li>Open the system Pro software and check the instrument icon in the upper-left corner to determine whether the instrument is connected to the computer. If the red circle with a line is visible, click on the instrument icon and choose the instrument in the pop-up window to make the connection.</li>
		<li>Select New Experiment to access the Plate Set-Up Helper pop-up window. From the Plate Set-Up Helper menu, select Configure Your Acquisition Settings.</li>
		<li>Select Monochromator from the settings menu for the optical configuration. Select FL (fluorescence) for the read mode and Kinetic for the read type.</li>
		<li>In the same configurations window, under Category, click on Wavelengths, and then set bandwidths to 9 nm for excitation and 15 nm for emission.</li>
		<li>Set the Number of Wavelength Pairs to 1. Set the wavelengths LM1 to 510 nm for excitation and to 540 nm for emission.</li>
		<li>Continue through the categories and select Plate Type next. Select the option that matches the plate type being used. 
		NOTE: It is important that the selection matches the plate type. The read heights are set by the system according to the selection.</li>
		<li>Next, select Read Area and highlight the area of the 96-well plate included in the experimental design.</li>
		<li>Select PMT and Optics, set PMT Gain to High and Flashes per read to 6. Check the box next to Read from Bottom if using a clear-bottom plate.</li>
		<li>Select Timing and set for 10 min intervals over a 70 min period.</li>
		<li>Select Shake, check the Before First Read box, and set for 5 s. Check the Between Reads box and set for 3 s. Set shake intensity for both to Low and Linear.</li>
		<li>Close the window. When the Plate Set-Up Helper window pops up, select Configure Your Plate Layout. Highlight the BL wells of the plate design and click on Plate Blank.</li>
		<li>Highlight each of the experimental rows, click on Add, name the group, and then select a color.</li>
		<li>Under Assignment Options below the plate design, select Series, and then define the series in the window and click on OK. Repeat for each group.</li>
	</ol>
	</li>
	<li>Prepare the zymosan suspension
	<ol>
		<li>While waiting for the system temperature to reach 37 &#176;C, resuspend 1 mg of zymosan particles in 5 mL of the live-cell imaging medium.
		<ol>
			<li>Add 1 mL of live-cell imaging medium to the vial containing the particles and collect them into a glass culture tube. Rinse the vial with an additional 1 mL of imaging solution and transfer to the same glass tube to ensure that all the particles are transferred. Add 3 mL of additional imaging solution to achieve a 0.2 mg/mL of particle suspension.</li>
		</ol>
		</li>
		<li>Vortex with quick pulses for 30-60 s. Then, use a probe sonicator to sonicate with 60 quick pulses. 
		NOTE: It is very important to create a homogenous suspension of particles and not let the suspension sit too long before adding to the experimental wells. Clumping recurs rapidly. The particle per cell density may need to be optimized depending on the source, treatment, and density of M&#934; used. In the studies presented, conjugated zymosan particles were used. However, conjugated E. coli and S. aureus are also available.</li>
	</ol>
	</li>
	<li>Add zymosan and read the plate
	<ol>
		<li>Aspirate the medium from the experimental wells and rinse 1x with 100 &#181;L of the live-cell imaging solution. Rinse the RBL wells with the live-cell imaging solution as well.</li>
		<li>Aspirate the live-cell imaging solution from experimental and RBL wells and replace it with 100 &#181;L of the zymosan particle suspension prepared in section 5.2.</li>
		<li>Open the plate tray of the fluorescent reader using the touchpad interface. Set the plate, without the lid, in the tray with the A1 well in the upper-left corner. Close the tray using the touchpad and click on the green Read button in the top menu.</li>
		<li>When the read is complete, save the file to the appropriate folder and export the data in a spreadsheet format by clicking on File and selecting Export.</li>
		<li>Calculate the mean &#177; SEM relative fluorescence for each replicate group at each time point (10 min, 20 min, 30 min, etc.) in the spreadsheet (Supplementary File 1) and transfer the data to graphing software.</li>
		<li>Use a line graph format to present the data and apply two-way ANOVA (Time x Treatment/MSC as factors) followed by Tukey&#39;s multiple comparisons test to determine differences between individual groups. 
		&#8203;NOTE: While the 96-well plate read is in progress, prepare the dynamic imaging plate for time-lapse image acquisition. Ensure that the dynamic imaging proceeds with the analysis of one experimental well at a time.</li>
	</ol>
	</li>
</ol>
6. Phagocytosis assay, dynamic imaging, Day 3
<ol>
	<li>Turn on the imaging system and computer. Double click to open the software. Select the Pro program mode.</li>
	<li>Check the stage area to ensure no samples are present and nothing is impeding the movement of the stage. Then, click on Calibrate Now.</li>
	<li>Under the Incubation menu on the sidebar on the right, check the box next to H Unit XL and set it to 37 &#176;C. 
	NOTE: Wait until the incubated stage is almost to the temperature before preparing the samples for imaging.</li>
	<li>Rinse the first experimental well with 750 &#181;L of imaging medium and replace it with 400 &#181;L of the zymosan particle suspension prepared in section 5.2. Leave the remaining wells in the growth medium. 
	NOTE: It may be necessary to vortex and sonicate the particle suspension again briefly if it has settled for more than 15 min.</li>
	<li>Place the slide on the incubated stage of the imaging system. Set a timer for 10 min.</li>
	<li>Use the imaging software, select Brightfield under the Locate tab, and then click on the eyepiece icon in the system configuration window below. With the 10x objective in place, use the eyepiece and focusing knob to focus on the cells.</li>
	<li>Select the Acquisition tab, use the Experiment drop-down menu, and then select a set of wavelengths that includes EGFP filter set to accommodate 509 nm excitation 533 nm emission wavelengths of the pH-sensitive dye.</li>
	<li>When there is ~2 min left on the timer, use the software to change the objective to 20x by clicking on the 20x icon in the objective menu.
	<ol>
		<li>Click on the Channels menu, select EGFP filters and use the Exposure menu to set the exposure time to 400 ms to detect the pH-sensitive green fluorophore once it has been enclosed in the phagolysosome.</li>
		<li>Click on Live and adjust the focus using the focusing knob.</li>
	</ol>
	</li>
	<li>Click on Stop&#160;to turn off the light and check the box next to the Time-lapse experimental setting at the top.</li>
	<li>In the Focusing Strategy menu select Software Autofocus. From the drop-down in the Autofocus menu, select Smart and Coarse settings to reduce the time of exposure to light while the autofocus is running.</li>
	<li>In the Time-Lapse menu, set the desired number of acquisitions to 30-60 and the interval time to 1 min.</li>
	<li>After the time-lapse parameters are set and after 10 min of addition of particles to the first well, click on the Start Experiment button to begin acquisition.</li>
	<li>When the acquisition is complete using the first experimental well, repeat steps 6.4-6.12 for each of the remaining experimental wells.</li>
	<li>Save all the experiment files with the date and parameters in the title to the appropriate folder.</li>
	<li>Close the software. Reopen the software in Processing mode and export the files in the MP4 format using the Export menu.</li>
</ol>

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S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+real+time+imaging+platform+to+quantify+macrophage+pahgocytosis.">A novel real time imaging platform to quantify macrophage pahgocytosis.</a> Biochemical Pharmacology. 116, 107-119 (2016).</li><li>Takahashi, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Flow+cytometric+quantitation+of+platelet+phagocytosis+by+monocytes+using+a+pH-sensitive+dye,+pHrodo-SE.">Flow cytometric quantitation of platelet phagocytosis by monocytes using a pH-sensitive dye, pHrodo-SE.</a> Journal of Immunological Methods. 447, 57-64 (2017).</li></ol>

The authors have no conflicts of interest to declare.

Analysis of phagocytosis using bioparticles conjugated to a pH-sensitive dye is a relatively new tool that has proven advantageous over traditional fluorescently labeled particles12,19,20. With traditional fluorescent-labeled particles, only end-point analysis is feasible. Detection is carried out with fluorescent microscopy and/or spectrofluorometry after washing or quenching particles that have not been taken up by the phagocy...

Mesenchymal stem cells (MSC) are progenitor cells that give rise to connective tissue cells. MSC are present in adult mammalian tissues and can be isolated from the bone marrow1. Due to their immunomodulatory properties, these cells are widely studied2. Early studies focused on MSC regulation of T-cells3,4,5,6 but more recently, their regulation of macrophage cells (M&#934;), a major cellular component of innate immunity, has received increased attention7,8,9,10,11,12,13,14. The importance of MSC-M&#934; interaction in the treatment of inflammatory disease is underscored by the fact that depletion of monocytes/macrophages abrogates the therapeutic effects of MSC in animal models8. Here, the focus is the cell contact interaction of the MSC with M&#934;. MSC&#160;have the capacity to&#160;regulate the phenotype of M&#934; by promoting the switch from inflammatory to anti-inflammatory responses, leading to tissue repair activities8,9,10,11, and much has been done to demonstrate these regulatory mechanisms. Under other circumstances, MSC can support or exacerbate a&#160;M&#934;-driven inflammatory response12,13 and enhance M&#934; phagocytic activity14,15. However, there is a critical lack of existing data that identifies the mechanisms whereby and the conditions under which MSC regulate M&#934; phagocytic activity.
M&#934; have families of receptors that recognize either opsonized (antibody or complement coated) or non-opsonized pathogens leading to phagocytosis16. The activation and activity of the latter is less well studied17. In a non-inflammatory in vitro environment, MSC&#160;enhance M&#934; phagocytosis of non-opsonized pathogens13. However, recognition of non-opsonized pathogens by M&#934; may be reduced after exposure to an inflammatory environment produced by lymphocytes during an adaptive immune response. IFN-&#947;, released by natural killer cells and effector lymphocytes, has an inhibitory effect on M&#934; phagocytosis of non-opsonized particles18. A co-culture model was developed to study the mechanisms of MSC direct contact regulation of M&#934; phagocytosis. The goal of the experiment presented here is to determine whether MSC&#160;regulate M&#934; phagocytosis of non-opsonized pathogens after M&#934; have been exposed to IFN-&#947; (Figure 1).

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>96 Well Black Polystyrene Microplate</td>
			<td>MilliporeSigma</td>
			<td>CLS3603-48EA</td>
			<td></td>
		</tr>
		<tr>
			<td>0.4% trypan blue solution</td>
			<td>MilliporeSigma</td>
			<td>T8154-20ML</td>
			<td></td>
		</tr>
		<tr>
			<td>15 mL and 50 mL Conical Sterile Polypropylene Centrifuge Tubes</td>
			<td>ThermoFisher</td>
			<td>339653</td>
			<td></td>
		</tr>
		<tr>
			<td>4-well Chambered Coverglass w/ non-removable wells</td>
			<td>ThermoFisher</td>
			<td>155382PK</td>
			<td></td>
		</tr>
		<tr>
			<td>Antibiotic-Antimycotic (100X)&#160;Gibco</td>
			<td>ThermoFisher</td>
			<td>15240096</td>
			<td></td>
		</tr>
		<tr>
			<td>Axiobserver 7 Imaging System</td>
			<td>Zeiss</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Bovine Serum Albumin (BSA)</td>
			<td>MilliporeSigma</td>
			<td>A8806-1G</td>
			<td></td>
		</tr>
		<tr>
			<td>Cell lifter</td>
			<td>MilliporeSigma</td>
			<td>CLS3008-100EA</td>
			<td></td>
		</tr>
		<tr>
			<td>Culture flasks, tissue culture treated, surface area 75&#160;cm2, canted neck, with cap, filtered</td>
			<td>MilliporeSigma</td>
			<td>C7231-120EA</td>
			<td></td>
		</tr>
		<tr>
			<td>D1 ORL UVA [D1]</td>
			<td>ATCC</td>
			<td>CRL-12424</td>
			<td>Mouse MSC Cell Line</td>
		</tr>
		<tr>
			<td>DMEM, High Glucose</td>
			<td>ThermoFisher</td>
			<td>11965092</td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum, qualified, heat inactivated</td>
			<td>ThermoFisher</td>
			<td>16140071</td>
			<td></td>
		</tr>
		<tr>
			<td>Hemocytometer</td>
			<td>FisherScientific</td>
			<td>02-671-51B</td>
			<td></td>
		</tr>
		<tr>
			<td>I-11.15</td>
			<td>ATCC</td>
			<td>CRL-2470</td>
			<td>Mouse M&#934; Cell Line</td>
		</tr>
		<tr>
			<td>LADMAC Cell Line</td>
			<td>ATCC</td>
			<td>CRL-2420</td>
			<td>LADMAC cells secrete the growth factor colony stimulating factor 1 (CSF-1).</td>
		</tr>
		<tr>
			<td>Live-Cell Imaging solution</td>
			<td>ThermoFisher</td>
			<td>A14291DJ</td>
			<td></td>
		</tr>
		<tr>
			<td>PBS, pH 7.4</td>
			<td>ThermoFisher</td>
			<td>10010031</td>
			<td></td>
		</tr>
		<tr>
			<td>pHrodo Green Zymosan Bioparticles Conjugate</td>
			<td>ThermoFisher</td>
			<td>P35365</td>
			<td></td>
		</tr>
		<tr>
			<td>Recombinant Murine IFN-&#947;</td>
			<td>Preprotech</td>
			<td>315-05</td>
			<td></td>
		</tr>
		<tr>
			<td>Spectramax i3X</td>
			<td>Molecular Devices</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Sterile Single Use Vacuum Filter Units, 250 mL, 0.2 &#181;m</td>
			<td>ThermoFisher</td>
			<td>568-0020</td>
			<td></td>
		</tr>
		<tr>
			<td>Sterile syringe filters, 0.2 micrometer</td>
			<td>ThermoFisher</td>
			<td>723-2520</td>
			<td></td>
		</tr>
		<tr>
			<td>Tissue-culture treated culture dishes, 100 mm x 20 mm</td>
			<td>MilliporeSigma</td>
			<td>CLS430167-100EA</td>
			<td></td>
		</tr>
		<tr>
			<td>Trypsin-EDTA (0.05%), phenol red</td>
			<td>ThermoFisher</td>
			<td>25300054</td>
			<td></td>
		</tr>
	</tbody>
</table>

mesenchymal stem cell regulation of macrophage phagocytosis; quantitation and imaging

Mesenchymal stem cells (MSC) have traditionally been studied for their regenerative properties, but more recently, their immunoregulatory characteristics have been at the forefront. They interact with and regulate immune cell activity. The focus of this study is the MSC regulation of macrophage phagocytic activity. Macrophage (M&#934;) phagocytosis is an important part of the innate immune system response to infection, and the mechanisms through which MSC modulate this response are under active investigation. Presented here is a method to study M&#934; phagocytosis of non-opsonized zymosan particles conjugated to a pH-sensitive fluorescent molecule while in co-culture with MSC. As phagocytic activity increases and the labeled zymosan particles are enclosed within the acidic environment of the phagolysosome, the fluorescence intensity of the pH-sensitive molecule increases. With the appropriate excitation and emission wavelengths, phagocytic activity is measured using a fluorescent spectrophotometer and kinetic data is presented as changes in relative fluorescent units over a 70 min period. To support this quantitative data, the change in the phagocytic activity is visualized using dynamic imaging. Results using this method demonstrate that when in co-culture, MSC enhance M&#934; phagocytosis of non-opsonized zymosan of both naive and IFN-&#947; treated M&#934;. These data add to the current knowledge of MSC regulation of the innate immune system. This method can be applied in future investigations to fully delineate the underlying cellular and molecular mechanisms.

After calculating mean &#177; SEM for each group at all time points, the data is presented in line graph format with the Y-axis as the Relative Fluorescent Intensity and the X-axis as Time. Supplementary File 1 provides an example of raw data from a kinetic read of the 96-well plate in a spreadsheet format.
In this study, the optimal results presented in Figure 3A, and Table 3 demonstrate that 1) co-culture with MSC&#160;enhances ...

Watch this Scientific Journal Video about Mesenchymal Stem Cell Regulation of Macrophage Phagocytosis; Quantitation and Imaging at JoVE.com

Mesenchymal Stem Cell Regulation of Macrophage Phagocytosis; Quantitation and Imaging

Presented here is a protocol to quantify and produce dynamic images of mesenchymal stem cell (MSC) mediated regulation of macrophage (M&#934;) phagocytosis of non-opsonized yeast (zymosan) particles that are conjugated to a pH-sensitive fluorescent molecule.

Mesenchymal stem cells (MSC) have traditionally been studied for their regenerative properties, but more recently, their immunoregulatory characteristics ...

mesenchymal-stem-cell-regulation-macrophage-phagocytosis-quantitation

Research

JoVE Journal

Immunology and Infection

3.1K Views.  Molloy College. Presented here is a protocol to quantify and produce dynamic images of mesenchymal stem cell (MSC) mediated regulation of macrophage (MΦ) phagocytosis of non-opsonized yeast (zymosan) particles that are conjugated to a pH-sensitive fluorescent molecule.

Video: Mesenchymal Stem Cell Regulation of Macrophage Phagocytosis; Quantitation and Imaging

Intravital Imaging of the Mouse Thymus using 2-Photon Microscopy

Two-photon Microscopy (TPM) provides image acquisition in deep areas inside tissues and organs. In combination with the development of new stereotactic tools and surgical procedures, TPM becomes a powerful technique to identify "niches" inside organs and to document cellular "behaviors" in live animals. While intravital imaging provides information that best resembles the real cellular behavior inside the organ, it is both more laborious and technically demanding in terms of required equipment/procedures than alternative ex vivo imaging acquisition. Thus, we describe a surgical procedure and novel "stereotactic" organ holder that allows us to follow the movements of Foxp3+ cells within the thymus.
Foxp3 is the master regulator for the generation of regulatory T cells (Tregs). Moreover, these cells can be classified according to their origin: ie. thymus-differentiated Tregs are called "naturally-occurring Tregs" (nTregs), as opposed to peripherally-converted Tregs (pTregs). Although significant amount of research has been reported in the literature concerning the phenotype and physiology of these T cells, very little is known about their in vivo interactions with other cells. This deficiency may be due to the absence of techniques that would permit such observations. The protocol described in this paper provides a remedy for this situation.
Our protocol consists of using nude mice that lack an endogenous thymus since they have a punctual mutation in the DNA sequence that compromises the differentiation of some epithelial cells, including thymic epithelial cells. Nude mice were gamma-irradiated and reconstituted with bone marrows (BM) from Foxp3-KIgfp/gfp mice. After BM recovery (6 weeks), each animal received embryonic thymus transplantation inside the kidney capsule. After thymus acceptance (6 weeks), the animals were anesthetized; the kidney containing the transplanted thymus was exposed, fixed in our organ holder, and kept under physiological conditions for in vivo imaging by TPM. We have been using this approach to study the influence of drugs in the generation of regulatory T cells.

We have developed novel laboratory tools and protocols for intravital imaging acquisition of the thymus. Our technique should help in the identification of &#x201C;niches&#x201D; within the thymus where T cell development occurs.

Two-photon Microscopy (TPM) provides image acquisition in deep areas inside tissues and organs. In combination with the development of new stereotactic ...

Live-cell Video Microscopy of Fungal Pathogen Phagocytosis

Phagocytic clearance of fungal pathogens, and microorganisms more generally, may be considered to consist of four distinct stages: (i) migration of phagocytes to the site where pathogens are located; (ii) recognition of pathogen-associated molecular patterns (PAMPs) through pattern recognition receptors (PRRs); (iii) engulfment of microorganisms bound to the phagocyte cell membrane, and (iv) processing of engulfed cells within maturing phagosomes and digestion of the ingested particle. Studies that assess phagocytosis in its entirety are informative1, 2, 3, 4, 5 but are limited in that they do not normally break the process down into migration, engulfment and phagosome maturation, which may be affected differentially. Furthermore, such studies assess uptake as a single event, rather than as a continuous dynamic process. We have recently developed advanced live-cell imaging technologies, and have combined these with genetic functional analysis of both pathogen and host cells to create a cross-disciplinary platform for the analysis of innate immune cell function and fungal pathogenesis. These studies have revealed novel aspects of phagocytosis that could only be observed using systematic temporal analysis of the molecular and cellular interactions between human phagocytes and fungal pathogens and infectious microorganisms more generally. For example, we have begun to define the following: (a) the components of the cell surface required for each stage of the process of recognition, engulfment and killing of fungal cells1, 6, 7, 8; (b) how surface geometry influences the efficiency of macrophage uptake and killing of yeast and hyphal cells7; and (c) how engulfment leads to alteration of the cell cycle and behavior of macrophages 9, 10.
In contrast to single time point snapshots, live-cell video microscopy enables a wide variety of host cells and pathogens to be studied as continuous sequences over lengthy time periods, providing spatial and temporal information on a broad range of dynamic processes, including cell migration, replication and vesicular trafficking. Here we describe in detail how to prepare host and fungal cells, and to conduct the video microscopy experiments. These methods can provide a user-guide for future studies with other phagocytes and microorganisms.

We describe methods for live-cell video microscopy of Candida albicans phagocytosis by macrophages. These methods enable stage-specific analysis of macrophage migration, recognition, engulfment and phagosome maturation and reveal novel aspects of phagocytosis.

Phagocytic clearance of fungal pathogens, and microorganisms more generally, may be considered to consist of four distinct stages: (i) migration of ...

In vivo Imaging Method to Distinguish Acute and Chronic Inflammation

Inflammation is a fundamental aspect of many human diseases. In this video report, we demonstrate non-invasive bioluminescence imaging techniques that distinguish acute and chronic inflammation in mouse models. With tissue damage or pathogen invasion, neutrophils are the first line of defense, playing a major role in mediating the acute inflammatory response. As the inflammatory reaction progresses, circulating monocytes gradually migrate into the site of injury and differentiate into mature macrophages, which mediate chronic inflammation and promote tissue repair by removing tissue debris and producing anti-inflammatory cytokines. Intraperitoneal injection of luminol (5-amino-2,3-dihydro-1,4-phthalazinedione, sodium salt) enables detection of acute inflammation largely mediated by tissue-infiltrating neutrophils. Luminol specifically reacts with the superoxide generated within the phagosomes of neutrophils since bioluminescence results from a myeloperoxidase (MPO) mediated reaction. Lucigenin (bis-N-methylacridinium nitrate) also reacts with superoxide in order to generate bioluminescence. However, lucigenin bioluminescence is independent of MPO and it solely relies on phagocyte NADPH oxidase (Phox) in macrophages during chronic inflammation. Together, luminol and lucigenin allow non-invasive visualization and longitudinal assessment of different phagocyte populations across both acute and chronic inflammatory phases. Given the important role of inflammation in a variety of human diseases, we believe this non-invasive imaging method can help investigate the differential roles of neutrophils and macrophages in a variety of pathological conditions.

In vivo Imaging Method to Distinguish Acute and Chronic Inflammation

We describe a non-invasive imaging method for distinguishing inflammatory stages. Systemic delivery of luminol reveals areas of acute inflammation dependent upon MPO activity in neutrophils. In contrast, injection of lucigenin allows for visualization of chronic inflammation dependent upon Phox activity in macrophages.

Inflammation is a fundamental aspect of many human diseases. In this video report, we demonstrate non-invasive bioluminescence imaging techniques that ...

Large-Scale Purification of Porcine or Bovine Photoreceptor Outer Segments for Phagocytosis Assays on Retinal Pigment Epithelial Cells

Analysis of one of the vital functions of retinal pigment epithelial (RPE) cells, the phagocytosis of spent aged distal fragments of photoreceptor outer segments (POS) can be performed in vitro. Photoreceptor outer segments with stacks of membranous discs containing the phototransduction machinery are continuously renewed in the retina. Spent POS are eliminated daily by RPE cells. Rodent, porcine/bovine and human RPE cells recognize POS from various species in a similar manner. To facilitate performing large series of experiments with little variability, a large stock of POS can be isolated from porcine eyes and stored frozen in aliquots. This protocol takes advantage of the characteristic of photopigments that display an orange color when kept in the dark. Under dim red light, retinae are collected in a buffer from opened eyecups cut in halves. The retinal cell suspension is homogenized, filtered and loaded onto a continuous sucrose gradient. After centrifugation, POS are located in a discrete band in the upper part of the gradient that has a characteristic orange color. POS are then collected, spun, resuspended sequentially in wash buffers, counted and aliquoted. POS obtained this way can be used for phagocytosis assays and analysis of protein activation, localization or interaction at various times after POS challenge. Alternatively, POS can be labeled with fluorophores, e.g., FITC, before aliquoting for subsequent fluorescence quantification of POS binding or engulfment. Other possible applications include the use of modified POS or POS challenge combined with stress conditions to study the effect of oxidative stress or aging on RPE cells.

This article describes the protocol for the purification of photoreceptor outer segment fragments (POS) via ultracentrifugation from porcine/bovine retinae using homogenization and sucrose gradient centrifugation. This protocol allows the preparation of large stocks of POS aliquots, labeled or unlabeled, that can then be stored at -80 &#176;C.

Analysis of one of the vital functions of retinal pigment epithelial (RPE) cells, the phagocytosis of spent aged distal fragments of photoreceptor outer ...

High Throughput Fluorometric Technique for Assessment of Macrophage Phagocytosis and Actin Polymerization

The goal of fluorometric analysis is to serve as an efficient, cost effective, high throughput method of analyzing phagocytosis and other cellular processes. This technique can be used on a variety of cell types, both adherent and non-adherent, to examine a variety of cellular properties. When studying phagocytosis, fluorometric technique utilizes phagocytic cell types such as macrophages, and fluorescently labeled opsonized particles whose fluorescence can be extinguished in the presence of trypan blue. Following plating of adherent macrophages in 96-well plates, fluorescent particles (green or red) are administered and cells are allowed to phagocytose for varied amounts of time. Following internalization of fluorescent particles, cells are washed with trypan blue, which facilitates extinction of fluorescent signal from bacteria which are not internalized, or are merely adhering to the cell surface. Following the trypan wash, cells are washed with PBS, fixed, and stained with DAPI (nuclear blue fluorescent label), which serves to label nuclei of cells. By a simple fluorometric quantification through plate reading of nuclear (blue) or particle (red/green) fluorescence we can examine the ratio of relative fluorescence units of green:blue and determine a phagocytic index indicative of amount of fluorescent bacteria internalized per cell. The duration of assay using a 96-well method and multichannel pipettes for washing, from end of phagocytosis to end of data acquisition, is less than 45 min. Flow cytometry could be used in a similar manner but the advantage of fluorometry is its high throughput, rapid method of assessment with minimal manipulation of samples and quick quantification of fluorescent intensity per cell. Similar strategies can be applied to non adherent cells, live labeled bacteria, actin polymerization, and essentially any process utilizing fluorescence. Therefore, fluorometry is a promising method for its low cost, high throughput capabilities in the study of cellular processes.

Here we present a protocol to quantify phagocytosis of fluorescent particles by adherent macrophage cell line using a fluorometric method. This method facilitates a high throughput quantification of particle internalization as well as the resulting actin polymerization.

The goal of fluorometric analysis is to serve as an efficient, cost effective, high throughput method of analyzing phagocytosis and other cellular ...

Macrophage Cholesterol Depletion and Its Effect on the Phagocytosis of Cryptococcus neoformans

Cryptococcosis is a life-threatening infection caused by pathogenic fungi of the genus Cryptococcus. Infection occurs upon inhalation of spores, which are able to replicate in the deep lung. Phagocytosis of Cryptococcus by macrophages is one of the ways that the disease is able to spread into the central nervous system to cause lethal meningoencephalitis. Therefore, study of the association between Cryptococcus and macrophages is important to understanding the progression of the infection. The present study describes a step-by-step protocol to study macrophage infectivity by C. neoformansin vitro. Using this protocol, the role of host sterols on host-pathogen interactions is studied. Different concentrations of methyl--cyclodextrin (MCD) were used to deplete cholesterol from murine reticulum sarcoma macrophage-like cell line J774A.1. Cholesterol depletion was confirmed and quantified using both a commercially available cholesterol quantification kit and thin layer chromatography. Cholesterol depleted cells were activated using Lipopolysacharide (LPS) and Interferon gamma (IFN&#947;) and infected with antibody-opsonized Cryptococcus neoformans wild-type H99 cells at an effector-to-target ratio of 1:1. Infected cells were monitored after 2 hr of incubation with C. neoformans and their phagocytic index was calculated. Cholesterol depletion resulted in a significant reduction in the phagocytic index. The presented protocols offer a convenient method to mimic the initiation of the infection process in a laboratory environment and study the role of host lipid composition on infectivity.

Macrophage Cholesterol Depletion and Its Effect on the Phagocytosis of Cryptococcus neoformans

In this article, a protocol for infection of macrophages with Cryptococcus neoformans is described. Also, a method for sterol depletion from the macrophages is explained. These protocols provide a guide to study fungal infections in vitro and examine the role of sterols in such infections.

Cryptococcosis is a life-threatening infection caused by pathogenic fungi of the genus Cryptococcus. Infection occurs upon inhalation of spores, which are ...

Assessment of the Immunomodulatory Properties of Human Mesenchymal Stem Cells (MSCs)

The immunomodulatory properties of multilineage human mesenchymal stem cells (MSCs) appear to be highly relevant for clinical use towards a wide-range of immune-related diseases. Mechanisms involved are increasingly being elucidated and in this article, we describe the basic experiment to assess MSC immunomodulation by assaying for suppression of effector leukocyte proliferation. Representing activation, leukocyte proliferation can be assessed by a number of techniques, and we describe in this protocol the use of the fluorescent cellular dye carboxyfluorescein succinimidyl ester (CFSE) to label leukocytes with subsequent flow cytometric analyses. This technique can not only assess proliferation without radioactivity, but also the number of cell divisions that have occurred as well as allowing for identification of the specific population of proliferating cells and intracellular cytokine/factor expression. Moreover, the assay can be tailored to evaluate specific populations of effector leukocytes by magnetic bead surface marker selection of single peripheral blood mononuclear cell populations prior to co-culture with MSCs. The flexibility of this co-culture assay is useful for investigating cellular interactions between MSCs and leukocytes.

Assessment of the Immunomodulatory Properties of Human Mesenchymal Stem Cells MSCs

The immunomodulatory properties of human mesenchymal stem cells (MSC) appear increasingly relevant for clinical application. Using a co-culture system of MSCs and peripheral blood leukocytes pre-stained with the fluorescent dye carboxyfluorescein succinimidyl ester (CFSE), we describe the in vitro assessment of MSC immunomodulation on effector leukocyte proliferation and specific subpopulations.

The immunomodulatory properties of multilineage human mesenchymal stem cells (MSCs) appear to be highly relevant for clinical use towards a wide-range of ...

Organoids as Model for Infectious Diseases: Culture of Human and Murine Stomach Organoids and Microinjection of Helicobacter Pylori

Recently infection biologists have employed stem cell derived cultures to answer the need for new and better models to study host-pathogen interactions. Three cellular sources have been used: Embryonic stem cells (ESC), induced pluripotent stem cells (iPSC) or adult stem cells. Here, culture of mouse and human gastric organoids derived from adult stem cells is described and used for infection with the gastric pathogen Helicobacter pylori. Human gastric glands are isolated from resection material, seeded in a basement matrix and embedded in medium containing growth factors epidermal growth factor (EGF), R-spondin, Noggin, Wnt, fibroblast growth factor (FGF) 10, gastrin and transforming growth factor (TGF) beta inhibitor. In these conditions, gastric glands grow into 3-dimensional organoids containing 4 lineages of the stomach. The organoids expand indefinitely and can be frozen and thawed similarly as cell lines. For infection studies, bacteria are microinjected into the lumen of the organoids. Infected organoids are processed for imaging. The described methods can be adapted to other organoids and infections with other bacteria, viruses or parasites. This allows the study of infection-induced changes in primary cells.

Stem cell derived cultures harbor tremendous potential to model infectious diseases. Here, the culture of mouse and human gastric organoids derived from adult stem cells is described. The organoids are microinjected with the gastric pathogen Helicobacter pylori.

Recently infection biologists have employed stem cell derived cultures to answer the need for new and better models to study host-pathogen interactions. ...

Saturated Fatty Acids Induce Ceramide-associated Macrophage Cell Death

Macrophages highly express epidermal fatty acid-binding protein and adipose fatty acid-binding protein. They actively uptake saturated and unsaturated fatty acids, which might play a critical role in regulating their immune functions. Numerous studies have shown that various fatty acids, saturated or unsaturated, may possess different impacts on cell growth and function. However, the approaches used for fatty acid preparation vary, which may lead to non-physiological results. Serum albumin, a natural carrier for fatty acids in mammalian peripheral blood, is recommended for forming a conjugate complex with the sodium salt of fatty acids to study fatty acid function in mammalian cells, thus minimizing the toxicity of fatty acid soap. Thus, a simple, relatively quick heating and sonicating method is developed and presented here for BSA-fatty acid conjugate formation. We describe a protocol using saturated fatty acids, especially stearic acids to induce severe cell death in mouse bone-marrow derived macrophages. We further demonstrate that saturated fatty acid-induced cell death is positively associated with accumulated cellular ceramide levels. This method can be extended for studies of the impact of fatty acid on other mammalian cells.

We illustrate a straight-forward method to derive murine primary macrophages from bone marrow cells and a simple method to prepare BSA-fatty acid conjugates. Then we demonstrate that saturated fatty acids can induce macrophage cell death, and such cell death is positively associated with cellular accumulation of ceramide levels.

Macrophages highly express epidermal fatty acid-binding protein and adipose fatty acid-binding protein. They actively uptake saturated and unsaturated ...

Fabricating Optical-quality Glass Surfaces to Study Macrophage Fusion

Visualizing the formation of multinucleated giant cells (MGCs) from living specimens has been challenging due to the fact that most live imaging techniques require propagation of light through glass, but on glass macrophage fusion is a rare event. This protocol presents the fabrication of several optical-quality glass surfaces where adsorption of compounds containing long-chain hydrocarbons transforms glass into a fusogenic surface. First, preparation of clean glass surfaces as starting material for surface modification is described. Second, a method is provided for the adsorption of compounds containing long-chain hydrocarbons to convert non-fusogenic glass into a fusogenic substrate. Third, this protocol describes fabrication of surface micropatterns that promote a high degree of spatiotemporal control over MGC formation. Finally, fabricating glass bottom dishes is described. Examples of use of this in vitro cell system as a model to study macrophage fusion and MGC formation are shown.

This protocol describes the fabrication of optical-quality glass surfaces adsorbed with compounds containing long-chain hydrocarbons that can be used to monitor macrophage fusion of living specimens and enables super-resolution microscopy of fixed specimens.