We thank all the fieldworkers for their help and the interviewees for their cooperation.

NOTE: Workflow for the detection of biomarkers for sperm function damage by flow cytometry includes (1) cell preparation, (2) staining with fluorescent reagents, and (3) flow cytometric analysis and data interpretation (Figure 1). The protocol follows the guidelines of the Ethics Committees of the Army Medical University (1.0/2013.4-12).
1. Cell preparation
<ol>
	<li>Obtain human semen samples by masturbation in plastic clinical specimen jars, preferably after 3-5 days of abstinence.</li>
	<li>Immediately incubate the semen samples in a 37 &#176;C incubator and completely liquefy the samples (up to 1 h).</li>
</ol>
2. Sperm cells counted using computer-aided sperm analysis (CASA)
<ol>
	<li>Mix the liquefied semen samples thoroughly.</li>
	<li>Add 10 &#181;L of semen into a sperm counting chamber (see the Table of Materials).</li>
	<li>Scan the slides in the Sperm Class Analyzer (see the Table of Materials), and count at least six areas and 400 spermatozoa for the estimation of sperm concentration. 
	&#8203;NOTE: Semen samples must be fresh, not frozen, for sperm apoptosis and MMP analysis.</li>
</ol>
3. Staining sperm cells
<ol>
	<li>Detection of sperm apoptosis using Annexin V-FITC/PI staining
	<ol>
		<li>Add 1 &#215; 106 sperm cells to a 1.5 mL centrifuge tube.</li>
		<li>Wash the cells with 500 &#181;L of cold phosphate-buffered saline (PBS).</li>
		<li>Centrifuge the sperm cell suspension at 300 &#215; g for 7 min and discard the supernatant.</li>
		<li>Resuspend the sperm cells in 200 &#181;L of 1x Binding Buffer.</li>
		<li>Add 2 &#181;L of FITC Annexin V and 2 &#181;L of PI (see the Table of Materials).</li>
		<li>Gently vortex the cells, incubate for 15 min at room temperature (25 &#176;C) in the dark, and place them in the flow cytometer immediately for analysis.</li>
	</ol>
	</li>
	<li>Analysis of mitochondrial membrane potential using JC-1 probe
	<ol>
		<li>Add 2 &#215; 106 sperm cells to a 1.5 mL centrifuge tube and centrifuge at 600 &#215; g for 5 min.</li>
		<li>Resuspend the sperm cell suspension in 1 mL of JC-1 working solution (see the Table of Materials).</li>
		<li>Gently vortex the cells and incubate for 20 min at 37 &#176;C in the dark.</li>
		<li>Centrifuge the suspension at 600 &#215; g for 5 min and discard the supernatant.</li>
		<li>Wash the pellet twice with 1 mL of PBS at a speed of 600 &#215; g for 5 min each.</li>
		<li>Resuspend the dyed sperm cells in 1 mL of PBS in flow cytometer tubes, and place the tubes in the flow cytometer immediately for analysis.</li>
		<li>Use carbonyl cyanide m-chlorophenyl hydrazone (CCCP) as a positive control. Resuspend the sperm cells (as previously described in step 3.2.1) in 1 mL of CCCP working solution (see the Table of Materials), and gently vortex the cells and incubate for 20 min at room temperature. Centrifuge the suspension at 600 &#215; g for 5 min and discard the supernatant. Repeat steps 3.2.2-3.2.6.</li>
	</ol>
	</li>
	<li>Sperm chromatin structure assay
	<ol>
		<li>Place an aliquot of liquefied raw semen (0.25 mL) into a cryotube, and immediately freeze the semen samples in liquid nitrogen (-196 &#176;C) until ready for the SCSA.</li>
		<li>Thaw the semen samples in a 37 &#176;C water bath and dilute them with TNE buffer (see the Table of Materials) to a concentration of 1-2 &#215; 106 cells/mL.</li>
		<li>Add 200 &#181;L of the diluted sample to a flow cytometer test tube and mix it with 400 &#181;L of acid solution (see the Table of Materials) for 30 s.</li>
		<li>Stain the samples with 1.2 mL of AO staining solution (see the Table of Materials) and place in the flow cytometer immediately for analysis.</li>
		<li>Use a reference sample as an internal standard to flow cytometer set-up and calibrations. Dilute the reference sample with 4 &#176;C TNE buffer to a concentration of 1-2 &#215; 106 cells/mL. Repeat steps 3.3.1-3.3.4. 
		NOTES: All solutions and buffers are stored at 4 &#176;C. (1) The semen should not be diluted before flash freezing. Raw semen samples should be thawed and diluted with TNE buffer at the time of flow cytometry measurements. (2) For infertility clinics, ~0.25 mL of raw semen should be flash-frozen in an ultracold freezer or a LN2 tank. These frozen aliquots can then be sent to an SCSA diagnostic laboratory on dry ice or in a LN2 dry shipper. (3) A human ejaculate sample that demonstrates heterogeneity of DNA integrity (e.g., 15% DNA fragmentation index [DFI]) was used as an internal standard reference.</li>
	</ol>
	</li>
</ol>
4. Flow cytometer setup
NOTE: Before starting the flow cytometer, the instrument&#39;s system check should be performed to verify analytical performance. Run the samples after all checks have been completed and passed.
<ol>
	<li>Open the flow cytometer software and start the cytometer.</li>
	<li>Collect sample data.
	<ol>
		<li>First, load a control sample onto the flow cytometer, and click RUN to start data collection (adjust settings if needed). Wait for the instrument to begin aspirating the sample and provide a real-time preview of detected events. 
		NOTE: The control sample: a negative control (unstained sperm cells) for sperm apoptosis; a positive control (CCCP-treated cells) for MMP; a reference sample for SCSA.</li>
		<li>Create dot plots for viewing data and select the x/y-axis parameters (such as FSC, SSC) and linear to specify data are displayed. Select and apply a polygonal gate to delineate the sperm population for analysis, and so that the instrument plots detected events in real-time.</li>
		<li>Analyze the sperm events within the region.
		<ol>
			<li>For sperm apoptosis, set the FL1 as the x-axis and the FL2 as the x-axis. To isolate the live, apoptotic, or necrotic cells, tap and drag the quadrant gate to subset the sperm populations down to four specific populations.</li>
			<li>For MMP, set the FL1 as the x-axis and the FL2 as the y-axis. Create a polygonal gate to subset the sperm populations down to two specific populations.</li>
			<li>For SCSA, set the FL4 as the x-axis (red fluorescence, 125/1,024 flow cytometry channels) and the FL1 as the y-axis (green fluorescence, 475/1,024 flow cytometry channels). Draw the gates at a 45&#176; angle to exclude cellular debris signals.</li>
		</ol>
		</li>
		<li>Set a run limit to indicate when to stop collecting data. Calculate a total of 10,000 sperm cells for each sample for sperm apoptosis, MMP, and SCSA analyses.</li>
		<li>Set the fluidics rate (slow, medium, and fast, or a custom fluidics rate), depending on the cell numbers. 
		NOTES: For SCSA analysis, to determine sperm concentrations, thaw the frozen raw sample and run it on the FCM. If the flow rate is &#62;250/s, dilute the sample to the correct flow rate. Measure all samples independently twice, and calculate the mean values. A reference sample was tested when every 10-15 samples were measured to ensure standardization and stability of the instrument from day-to-day.</li>
		<li>Set the threshold to eliminate debris and noise from cell samples. Apply these settings for all samples in the experiment.</li>
		<li>If needed, set the color compensation to correct fluorescence spillover.</li>
		<li>Gently back-pipette the samples before loading them onto the flow cytometer, name the sample, and run the samples.</li>
		<li>Once all samples have been run, save the sample data as FCS files by giving them a file name for further software analysis. Save the work template of the current experiment for retrieval in future runs (optional).</li>
	</ol>
	</li>
</ol>
5. Data analysis
<ol>
	<li>Import the data into the data analysis software for the flow cytometer (see the Table of Materials).</li>
	<li>Double-click the first sample in workspace. Wait until a Graph window opens, showing a plot of events along FSC versus SSC parameters. Create a gate that isolates the sperm population included within the gate, producing a &#39;child&#39; population from the parent set of events.</li>
	<li>Double-click within the gated area, and open a new Graph window containing only the sperm events. Set the x- and y-axis parameters to select fluorescent channel.</li>
	<li>Select the Gate tool. Click within the plot to make the gates appear, so that the created gates isolate the different cell populations.</li>
	<li>Right-click (or control-click) any of the highlighted rows, and select Copy analysis to group. Apply the gating tree to all samples within the group.</li>
	<li>Save and export the data table.</li>
</ol>

<ol>
	<li>Agarwal, A., Mulgund, A., Hamada, A., Chyatte, M. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+unique+view+on+male+infertility+around+the+globe.">A unique view on male infertility around the globe.</a> Reproductive Biology and Endocrinology. 13 (1), 1-9 (2015).</li><li>Nachtigall, R. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=International+disparities+in+access+to+infertility+services.">International disparities in access to infertility services.</a> Fertility and Sterility. 85 (4), 871-875 (2006).</li><li>Agarwal, A., Allamaneni, S. S. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sperm+DNA+damage+assessment:+a+test+whose+time+has+come.">Sperm DNA damage assessment: a test whose time has come.</a> Fertility and Sterility. 84 (4), 850-853 (2005).</li><li>Pe&#241;a, F. J., Ortega Ferrusola, C., Mart&#237;n Mu&#241;oz, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=New+flow+cytometry+approaches+in+equine+andrology.">New flow cytometry approaches in equine andrology.</a> Theriogenology. 86 (1), 366-372 (2016).</li><li>Oosterhuis, G. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measuring+apoptosis+in+human+spermatozoa:+a+biological+assay+for+semen+quality.">Measuring apoptosis in human spermatozoa: a biological assay for semen quality.</a> Fertility and Sterility. 74 (2), 245-250 (2000).</li><li>Koopman, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Annexin+V+for+flow+cytometric+detection+of+phosphatidylserine+expression+on+B+cells+undergoing+apoptosis.">Annexin V for flow cytometric detection of phosphatidylserine expression on B cells undergoing apoptosis.</a> Blood. 84 (5), 1415-1420 (1994).</li><li>Freitas, M. J., Vijayaraghavan, S., Fardilha, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Signaling+mechanisms+in+mammalian+sperm+motility.">Signaling mechanisms in mammalian sperm motility.</a> Biology of Reproduction. 96 (1), 2-12 (2017).</li><li>Lehti, M. S., Sironen, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Formation+and+function+of+sperm+tail+structures+in+association+with+sperm+motility+defects.">Formation and function of sperm tail structures in association with sperm motility defects.</a> Biology of Reproduction. 97 (4), 522-536 (2017).</li><li>Durairajanayagam, D., Singh, D., Agarwal, A., Henkel, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Causes+and+consequences+of+sperm+mitochondrial+dysfunction.">Causes and consequences of sperm mitochondrial dysfunction.</a> Andrologia. 53 (1), 13666 (2021).</li><li>Agnihotri, S. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mitochondrial+membrane+potential+(MMP)+regulates+sperm+motility.">Mitochondrial membrane potential (MMP) regulates sperm motility.</a> In Vitro Cellular and Developmental Biology. Animal. 52 (9), 953-960 (2016).</li><li>Smiley, S. T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intracellular+heterogeneity+in+mitochondrial+membrane+potentials+revealed+by+a+J-aggregate-forming+lipophilic+cation+JC-1.">Intracellular heterogeneity in mitochondrial membrane potentials revealed by a J-aggregate-forming lipophilic cation JC-1.</a> Proceedings of the National Academy of Sciences of the United States of America. 88 (9), 3671-3675 (1991).</li><li>Evenson, D. P., Darzynkiewicz, Z., Melamed, M. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Relation+of+mammalian+sperm+chromatin+heterogeneity+to+fertility.">Relation of mammalian sperm chromatin heterogeneity to fertility.</a> Science. 210 (4474), 1131-1133 (1980).</li><li>Evenson, D. P., Djira, G., Kasperson, K., Christianson, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Relationships+between+the+age+of+25,445+men+attending+infertility+clinics+and+sperm+chromatin+structure+assay+(SCSA&#174;)+defined+sperm+DNA+and+chromatin+integrity.">Relationships between the age of 25,445 men attending infertility clinics and sperm chromatin structure assay (SCSA&#174;) defined sperm DNA and chromatin integrity.</a> Fertility and Sterility. 114 (2), 311-320 (2020).</li><li>Evenson, D. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sperm+chromatin+structure+assay+(SCSA&#174;).">Sperm chromatin structure assay (SCSA&#174;).</a> Methods in Molecular Biology. 927, 147-164 (2013).</li><li>Agarwal, A., Said, T. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Role+of+sperm+chromatin+abnormalities+and+DNA+damage+in+male+infertility.">Role of sperm chromatin abnormalities and DNA damage in male infertility.</a> Human Reproduction Update. 9 (4), 331-345 (2003).</li><li>Ricci, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Apoptosis+in+human+sperm:+its+correlation+with+semen+quality+and+the+presence+of+leukocytes.">Apoptosis in human sperm: its correlation with semen quality and the presence of leukocytes.</a> Human Reproduction. 17 (10), 2665-2672 (2002).</li><li>Zhang, H. -. B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Early+apoptotic+changes+in+human+spermatozoa+and+their+relationships+with+conventional+semen+parameters+and+sperm+DNA+fragmentation.">Early apoptotic changes in human spermatozoa and their relationships with conventional semen parameters and sperm DNA fragmentation.</a> Asian Journal of Andrology. 10 (2), 227-235 (2008).</li><li>. WHO laboratory manual for the examination and processing of human semen Available from: <a target="_blank" href="https://www.who.int/publications/i/item/9789240030787">https://www.who.int/publications/i/item/9789240030787</a> (2022)</li><li>Evenson, D. P., Wixon, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Environmental+toxicants+cause+sperm+DNA+fragmentation+as+detected+by+the+Sperm+Chromatin+Structure+Assay+(SCSA).">Environmental toxicants cause sperm DNA fragmentation as detected by the Sperm Chromatin Structure Assay (SCSA).</a> Toxicology and Applied Pharmacology. 207 (2), 532-537 (2005).</li><li>Wang, Y. X., 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=Phthalate+exposure+in+association+with+serum+hormone+levels,+sperm+DNA+damage+and+spermatozoa+apoptosis:+A+cross-sectional+study+in+China.">Phthalate exposure in association with serum hormone levels, sperm DNA damage and spermatozoa apoptosis: A cross-sectional study in China.</a> Environmental Research. 150, 557-565 (2016).</li><li>Ni, W., 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=Diurnal+variation+in+sperm+DNA+fragmentation:+analysis+of+11,382+semen+samples+from+two+populations+and+in+vivo+animal+experiments.">Diurnal variation in sperm DNA fragmentation: analysis of 11,382 semen samples from two populations and in vivo animal experiments.</a> Chronobiology International. 36 (11), 1455-1463 (2019).</li></ol>

The authors declare that there are no conflicts of interest.

Chromatin integrity, MMP, and apoptosis of human spermatozoa have been found to be valuable predictors of reproductive outcomes. The latest-released WHO laboratory manual for the examination and processing of human semen (sixth edition) also highlighted some of these indicators (chromatin integrity and apoptosis) as extended examinations beyond the basic examination of routine parameters such as sperm count18. Recent publications also suggest that these indicators may be more sensitive markers of response to external hazardous exposures, indicating their potential for the identification of reproductive damage at an earlier stage19,20. Combining these indicators with routine examinations may also provide a more comprehensive understanding about the profile of sperm dysfunction and the complexity of male reproductive damage in the population.
There are several key issues that substantially determine the success of sperm analysis with FCM. First, the measurement of sperm MMP and apoptosis requires immediate examination after the semen is liquefied. To minimize the time cost, two technicians can separately take charge of the pretreatment of MMP and apoptosis analysis of a sample. As the pretreatment of apoptosis is simpler, it would transfer to the flow-cytometric step faster than the MMP analysis. For the SCSA analysis, fresh semen samples should be cryopreserved immediately upon availability after liquefaction. The sperm samples can then be stored in liquid nitrogen for a relatively long period and do not need immediate examination.
Accordingly, the in-site time cost of the experiment can be compressed to 40 min, which is the duration of MMP analysis plus the flow-cytometric step of sperm analysis. Second, the setup of the gating in the flow cytometric platform must be decided for each batch of samples separately. The sperm samples with clear cell subgroups in the scatter plot can be selected as the reference to draw the gating area. Third, as there are no widely accepted clinical reference values for the indicators of this experiment, historic results may be used as an important tool for quality control. Positive and negative controls are also encouraged to be set in each batch of measurements, especially for SCSA and MMP.
The representative results of sperm analysis provided here are derived using an Accuri C6. However, the technique could be applied to other commercial platforms with minor modification. Usually, a total of 5 &#215; 106 sperm cells would be needed to meet the requirement for the measurement of all the indicators. If the sperm concentration of a sample is much lower than the average level, the need for the volume of semen would increase.
Similar to routine sperm parameters, there is also noticeable intraindividual variation in the chromatin integrity, MMP, and apoptosis of human spermatozoa21. Accordingly, multiple tests of samples collected at different times may provide a more accurate estimation of the sperm function damage level. Although there is no recommended period of abstinence before sperm sampling for the flow cytometric analysis, 2-7 days of ejaculatory abstinence, suggested for routine sperm analysis by WHO, may be adopted. It may help to improve the comparability of the results among laboratories and among different samples collected from the same men.
A major limitation of this method is that two of the three tested biomarkers - the apoptosis and mitochondrial membrane potential - require fresh semen samples. This may limit their application to men who can provide semen samples to the laboratory. For the test of DNA damage (SCSA), reference samples should be prepared before the experiment to calibrate the flow cytometer. Of note, the application of the present protocol requires an FCM instrument in the lab, which is still a considerable challenge for many clinical laboratories, although cooperation with a third-party service may be an alternative choice in some regions.
Additionally, the expense of the dyes and other reagents is also a financial factor for males who may need the examination. Lastly, the protocol may need modification if different brands or versions of FCM are used to examine the biomarkers. In summary, this paper presents a practical approach to estimate three biomarkers of human spermatozoa damage by a single flow cytometry machine. This may provide valuable information about male reproductive health and complement the routine sperm examination.

Infertility has become a public health problem, with male infertility contributing to 40%-50% of all cases1,2. Although conventional semen quality analysis plays an important role in determining male fertility potential, approximately 15% of patients with infertility have normal sperm parameters such as sperm count, motility, and morphology3. Moreover, routine sperm examinations have poor repeatability, provide limited information on sperm function, and cannot give an accurate evaluation of male fertility or reflect the subtle defects of sperm. Multiple techniques have been developed to test sperm function, such as the hemizona assay (HZA), the sperm penetration assay, the hypo-osmotic swelling test, the antisperm antibody testing, but these methods are time-consuming and vulnerable to subjective influences of the operators. Therefore, it is necessary to develop rapid and accurate methods for sperm function analysis.
FCM is a rapid, single-cell analysis technology developed in the 1970s, which has been widely used in various fields of cell biology and medicine. FCM is a robust tool for the evaluation of sperm function that analyzes spermatozoa labeled with a specific fluorescence probe4. The spermatozoa pass through single- or multi-channel lasers, and scattered light and emitted fluorescence are produced by a laser beam. The scattered light includes forward scattered light (FSC) and side scattered light (SSC), which reflects the size of the tested cell and the cell granularity or internal structure. These signals are collected, displayed, and analyzed by the computer system, and, consequently, a series of characteristics from the spermatozoa are measured quickly and accurately. Therefore, FCM is a rapid, objective, multi-dimensional, and high-throughput technique that has gained increasing attention in the field of sperm analysis. The application of FCM can make up for shortcomings in traditional methods and provides a new approach for the detection of sperm internal structure and function.
Sperm apoptosis is closely related to male fertility5. Detection of sperm apoptosis is an important index to evaluate sperm function at a molecular level. FCM is widely recognized as a reliable and sensitive method to detect sperm apoptosis using Annexin V-FITC/PI staining. The basic principle is that phosphatidylserine (PS) is transferred from the inner layer of the cell membrane to its outer layer in the early stage of apoptosis. Annexin V is a Ca2+-dependent phospholipid protein (usually labeled by FITC) that has a high affinity for PS, thus, detects PS exposed to the outer surface of the cell membrane6. Necrosis and apoptosis can be distinguished in combination with Pl staining. Therefore, the method of Annexin V-FITC/PI double staining is widely used, as it is rapid, simple, and easy to detect different apoptotic sperm cells.
A mature mammalian sperm contains approximately 72-80 mitochondria7, suggesting a biological reason for the retention of sperm mitochondria8. Sperm mitochondria have been found to play important roles in sustaining sperm motility and fertility9. The JC-1 stain, which can be used as an indicator of MMP in a variety of cell types, is one of the most popular fluorochromes for sperm mitochondrial activity assessment10. JC-1 is a cationic dye that potential-dependently accumulates in the mitochondria. JC-1 has a maximum fluorescence emission at 525 nm (green) and forms J-aggregates11 when binding to membranes with a high potential (&#916;&#936;m, 80-100 mV), resulting in a shift in fluorescence emission to ~590 nm (orange-red). Consequently, sperm mitochondrial depolarization is indicated by a decrease in the red/green fluorescence intensity ratio, and FCM can be used to detect MMP levels in human semen samples.
The SCSA methodology was invented by Evenson et al.12, and is considered a precise and repeatable test with unique dual-parameter data (red vs green fluorescence) on a 1,024 &#215; 1,024 channel scale13. In damaged sperm, DNA and altered proteins in sperm nuclei are labeled by AO, and breakages of the DNA strand are measured by red fluorescence, while intact double strands emit green fluorescence in FCM14. Nowadays, many methods have been developed to estimate sperm DNA integrity. However, unlike SCSA, these assays are often labor-intensive and lack the ability for a diagnosis of male infertility. The SCSA test results significantly corelate with human DNA pregnancy and miscarriage, provide compelling evidence that SCSA may be useful in human semen analysis, and may serve as a valuable tool to infertility clinicians15.
Chromatin integrity, MMP, and apoptosis reflect different aspects of sperm function, and thus, the combination of these biomarkers may provide a more comprehensive insight into sperm status. FCM can be used for separate measurements of either chromatin integrity, MMP, or apoptosis in human semen specimens. Although the expense of FCM and the cost of dyes have limited the wide application of these techniques in clinical laboratories for reproductive health, their value for fecundity estimation is being accepted.
However, as each of the experiments requires pretreatment of sperm samples, and all pretreated samples need to be tested as soon as possible, simultaneous measurement of all the three biomarkers for a sample with a single FCM may lead to a long waiting time for some of the experiments and obstruct the reliability of the results. This is because the sperms receive additional damage during the waiting process, if the protocol is not properly arranged taking all the three experiments entirely into consideration. This paper presents a protocol that realizes the fluent measurement of all the three biomarkers in a single cytometry without substantial compromise of experiment quality induced by prolonged waiting times.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>0.1 M citric acid buffer</td>
			<td>Sigma-Aldrich Chemical Co., USA</td>
			<td>251275-5G</td>
			<td>Add 21.01 g/L citric acid monohydrate (FW = 210.14; 0.10 M) to 1.0 L H2O. Store up to several months at 4 &#176;C.</td>
		</tr>
		<tr>
			<td>0.2 M Na2PO4 buffer</td>
			<td>Sigma-Aldrich Chemical Co., USA</td>
			<td>V900061-500G</td>
			<td>Add 28.4 g sodium phosphate dibasic (FW = 141.96; 0.2 M) to 1.0 L H2O. Store up to several months at 4 &#176;C.</td>
		</tr>
		<tr>
			<td>10 mM CCCP stock solution</td>
			<td>Sigma-Aldrich Chemical Co., USA</td>
			<td>C2759</td>
			<td>Add 20.46 mg CCCP to 10.0 mL DMSO,making up to the final of CCCP in a concentration of 10mM, aliquot and store at &#8722;80 &#176;C.</td>
		</tr>
		<tr>
			<td>10 &#181;M CCCP working solution</td>
			<td></td>
			<td></td>
			<td>Add 10 mL of PBS to a 15 mL polypropylene centrifuge tube and add 10 &#956;L CCCP stock solution, making up to the final of CCCP in a concentration of 10 &#181;M.</td>
		</tr>
		<tr>
			<td>1 mM JC-1 stock solution</td>
			<td>Sigma-Aldrich Chemical Co., USA</td>
			<td>T4069</td>
			<td>JC-1 is purchased lyophilized. Add a small quantity of DMSO to the vial and vortex for several minutes until all the dye has dissolved. Transfer the solution to a light-tight tube and rinse the vial with appropriate volume of DMSO, making up to the final of JC-1 in a concentration of 1 mg/mL&#160; aliquot and store at &#8722;20 &#176;C.</td>
		</tr>
		<tr>
			<td>37 &#176;C incubator</td>
			<td>Thermo Scientific, USA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>5 &#181;M JC-1 working solution</td>
			<td></td>
			<td></td>
			<td>Add 10 mL of PBS to a 15 mL polypropylene centrifuge tube and add 50 &#956;L from a thawed JC-1 stock aliquot. Stir gently to assure a homogenous dilution. This solution must be stored in the dark and used promptly.</td>
		</tr>
		<tr>
			<td>Accuri C6 Flow cytometer</td>
			<td>BD Pharmingen, San Diego, CA, United States</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Acid solution, pH 1.2</td>
			<td></td>
			<td></td>
			<td>Combine 20.0 mL of 2.0 N HCl (0.08 N), 4.39 g of NaCl (0.15 M), and 0.5 mL of Triton X-100 (0.1%) in H2O for a final volume of 500 mL. Adjust pH to 1.2 with 5 mol/L HCl.</td>
		</tr>
		<tr>
			<td>Acridine Orange (AO) stock solution, 1.0 mg/mL</td>
			<td>Polysciences, Inc, Warrington, Pa</td>
			<td>65-61-2</td>
			<td>Dissolve chromatographically purified AO in dd-H2O at 1.0 mg/mL.</td>
		</tr>
		<tr>
			<td>AO staining solution (working solution)</td>
			<td></td>
			<td></td>
			<td>Add 600 &#956;L of AO stock solution to each 100 mL of staining buffer.</td>
		</tr>
		<tr>
			<td>Biological safety hood</td>
			<td>Airtech, USA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Computer-aided sperm analysis system (CASA )</td>
			<td>Microptic, Barcelona, Spain</td>
			<td></td>
			<td>Sperm Class Analyzer 5.3.00</td>
		</tr>
		<tr>
			<td>Sperm Counting Chamber</td>
			<td>Goldcyto, Spain</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Equipments</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>FITC Annexin V Apoptosis Detection Kit I</td>
			<td>BD Biosciences, San Jose, CA</td>
			<td>556547</td>
			<td>Included: (1) FITC Annexin V is bottled at 100 ng/&#181;L; (2) Propidium Iodide (PI):The PI Staining Solution is composed of 50 &#181;g PI/mL in PBS (pH 7.4) and is 0.2 &#181;M sterile filtered; (3) 10x Binding Buffer: 0.1 M Hepes (pH 7.4), 1.4 M NaCl, 25 mM CaCl2. For a 1x working solution, dilute 1 part of the 10x Annexin V Binding Buffer to 9 parts of distilled water. Store at 4 &#176;C and protected from prolonged exposure to light. Do not freeze.</td>
		</tr>
		<tr>
			<td>FlowJo&#160;10</td>
			<td>Tree Star, Inc., San Carlos, CA, USA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Horizontal centrifuge</td>
			<td>Thermo Scientific, USA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>liquid nitrogen tank</td>
			<td>Thermolyne, USA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Materials</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>PBS</td>
			<td>Beyotime, Shanghai, China</td>
			<td>C0221A</td>
			<td>Ready-to-use PBS buffers is purchased and stored at room temperature</td>
		</tr>
		<tr>
			<td>Staining buffer, pH 6.0</td>
			<td></td>
			<td></td>
			<td>Combine 370 mL of 0.10 M citric acid buffer, 630 mL of 0.20 M Na2PO4 buffer, 372 mg of EDTA (disodium, FW = 372.24; 1 mM), and 8.77 g of NaC1 (0.15 M). Mix overnight on a stir plate to insure that the EDTA is entirely in solution. pH to 6.0 with saturated NaOH solution.</td>
		</tr>
		<tr>
			<td>The reference sample for SCSA analysis</td>
			<td></td>
			<td></td>
			<td>The reference sample was diluted with cold (4 &#176;C) TNE buffer to a working concentration of 1&#8211;2 &#215; 106 cells/mL, and used to set the green at 475/1,024 flow cytometry channels and set the red at 125/1,024 flow cytometry channels.</td>
		</tr>
		<tr>
			<td>TNE buffer, 1x, pH 7.4 (working solution)</td>
			<td></td>
			<td></td>
			<td>Combine 60 mL of 10x TNE and 540 mL of H2O. Check pH (7.4).</td>
		</tr>
		<tr>
			<td>TNE buffer, 10x, pH 7.4</td>
			<td>Perfemiker, Shanghai, China</td>
			<td>PM11733</td>
			<td>Ready-to-use buffers is purchased and stored at 4 &#176;C.</td>
		</tr>
	</tbody>
</table>

flow cytometric analysis of biomarkers for detecting human sperm functional defects

The conventional semen parameter analysis is widely used to assess male fertility. However, studies have found that ~15% of infertile patients show no abnormalities in conventional semen parameters. Additional technologies are needed to explain the idiopathic infertility and detect subtle sperm defects. Currently, biomarkers of sperm function, including sperm apoptosis, mitochondrial membrane potential (MMP), and DNA damage, reveal sperm physiology at the molecular level and are capable of predicting male fertility.
With flow cytometry (FCM) techniques, each of these markers can be rapidly, accurately, and precisely measured in human semen samples, but time costs substantially increase and results could be obstructed if all the biomarkers need to be tested with a single cytometer. In this protocol, after collection and immediate incubation at 37 &#176;C for liquefication, semen samples were further analyzed for sperm apoptosis using Annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI) staining. The MMP was labeled with 5,5&#8242;,6,6&#8242;-tetrachloro-1,1&#8242;,3,3&#8242;-tetraethyl-benzimidazolylcarbocyanine iodide (JC-1) probe, and DNA damage was assessed using the sperm chromatin structure assay (SCSA) with acridine orange (AO) staining. Thus, flow cytometric analysis of sperm function markers can be a practical and reliable toolkit for the diagnosis of infertility and evaluation of sperm function at both bench and bed.

Figure 2 shows the measurement of sperm apoptosis using Annexin V-FITC/PI staining. The FITC signal (green fluorescence) was measured in the FL1 channel, and the PI signal (red fluorescence) was measured in the FL2 channel. In the Annexin V/PI bivariate analysis, the quadrant makers identified four distinctive sperm populations. The results were expressed as the percentages of Annexin V-/PI&#8722; sperm (viable or live cells), Annexin V+/PI&#8722; sperm (early apoptotic cells or apoptotic cells), Annexin V+/PI+ sperm (late apoptotic cells), and Annexin V&#8722;/PI+ sperm (necrotic cells)16,17 (Figure 2B). A negative control (unstained sperm cells) was also used to set up compensation and quadrants (Figure 2A).
Figure 3 shows the measurement of MMP using JC-1 probe in human sperm. MMP % is presented as the orange-red/(green + orange-red) fluorescence ratio by analyzing the cytogram. A good-quality semen sample usually shows high orange-red fluorescence and low green fluorescence (active mitochondria, upper-left quadrant) (Figure 3A). Conversely, a poor-quality semen sample usually shows low orange-red fluorescence and high green fluorescence (inactive mitochondria, lower-right quadrant), possibly due to mitochondrial disruption (Figure 3B).
Figure 4 shows the data of SCSA13,14. These typical SCSA cytograms were obtained from two individual samples. Sample A came from a fertile man and sample B from an infertile man. Analysis of the flow cytometric data was carried out using FlowJo software. Cytograms show the source of each component of SCSA data. The x-axis (red fluorescence with 1,024 gradations of red fluorescence) indicates fragmented DNA; the y-axis (green fluorescence with 1,024 gradations) indicates native DNA stainability. The dotted line at y = 750 represents the boundary of normal sperm. Above that line of y = 750 are sperm with partially uncondensed chromatin, which were determined as immature sperm.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/63790/63790fig01.jpg" /> 
Figure 1: Workflow for the detection of biomarkers for sperm function damage by flow cytometry. Semen samples were obtained and pretreated as described in protocol step 1. (1) Cell preparation, (2) staining with fluorescent reagents, and (3) flow cytometric analysis and data interpretation. Abbreviations: MMP = mitochondrial membrane potential; SCSA = sperm chromatin structure assay; PBS = phosphate-buffered saline; AO = acridine orange. <a href="https://www.jove.com/files/ftp_upload/63790/63790fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/63790/63790fig02.jpg" /> 
Figure 2: Representative results of sperm apoptosis using Annexin V-FITC/PI staining. The lower left quadrant contains Annexin V-/PI&#8722; sperm (viable or live cells), the lower right quadrant shows Annexin V+/PI&#8722; sperm (early apoptotic cells or apoptotic cells), the upper right quadrant represents Annexin V+/PI+ sperm (late apoptotic cells), and the upper left quadrant contains Annexin V&#8722;/PI+ sperm (necrotic cells). (A) Negative control (unstained sperm cells); (B) a sample with sperm apoptosis. Abbreviations: FITC = fluorescein isothiocyanate; PI = propidium iodide. <a href="https://www.jove.com/files/ftp_upload/63790/63790fig02large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/63790/63790fig03.jpg" /> 
Figure 3: Measurement of mitochondrial membrane potential using JC-1 probe. (A) The sperm subpopulation with high MMP. (B) The sperm subpopulation with low MMP. Set FL1-A and FL2-A as the x axis (green fluorescence) and the y-axis (orange-red fluorescence), respectively. Abbreviations: MMP = mitochondrial membrane potential. <a href="https://www.jove.com/files/ftp_upload/63790/63790fig03large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/63790/63790fig04.jpg" /> 
Figure 4: Detecting DNA damage in human sperm using sperm chromatin structure assay. (A) A semen sample with normal chromatin structure. (B) A semen sample with high proportion of spermatozoa with abnormal chromatin structure. FlowJo software was used to make computer gates around the cell populations identified as: 1) normal sperm, 2) HDS sperm, 3) DFI sperm, and 4) cell debris, and percentages of HDS and DFI sperm were calculated. Abbreviation: SCSA = sperm chromatin structure assay; HDS = high DNA stainability; DFI = DNA fragmentation index. <a href="https://www.jove.com/files/ftp_upload/63790/63790fig04large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about Flow Cytometric Analysis of Biomarkers for Detecting Human Sperm Functional Defects at JoVE.com

Flow Cytometric Analysis of Biomarkers for Detecting Human Sperm Functional Defects

The present protocol provides a practical solution that allows for the measurement of apoptosis, mitochondrial membrane potential, and DNA damage in human sperm with a single cytometer.

The conventional semen parameter analysis is widely used to assess male fertility. However, studies have found that ~15% of infertile patients show no ...

flow-cytometric-analysis-biomarkers-for-detecting-human-sperm

Research

JoVE Journal

Medicine

2.0K Views.  Army Medical University (Third Military Medical University). The present protocol provides a practical solution that allows for the measurement of apoptosis, mitochondrial membrane potential, and DNA damage in human sperm with a single cytometer.

Video: Flow Cytometric Analysis of Biomarkers for Detecting Human Sperm Functional Defects

Dissection of Human Vitreous Body Elements for Proteomic Analysis

The vitreous is an optically clear, collagenous extracellular matrix that fills the inside of the eye and overlies the retina. 1,2 Abnormal interactions between vitreous substructures and the retina underlie several vitreoretinal diseases, including retinal tear and detachment, macular pucker, macular hole, age-related macular degeneration, vitreomacular traction, proliferative vitreoretinopathy, proliferative diabetic retinopathy, and inherited vitreoretinopathies. 1,2 The molecular composition of the vitreous substructures is not known. Since the vitreous body is transparent with limited surgical access, it has been difficult to study its substructures at the molecular level. We developed a method to separate and preserve these tissues for proteomic and biochemical analysis. The dissection technique in this experimental video shows how to isolate vitreous base, anterior hyaloid, vitreous core, and vitreous cortex from postmortem human eyes. One-dimensional SDS-PAGE analyses of each vitreous component showed that our dissection technique resulted in four unique protein profiles corresponding to each substructure of the human vitreous body. Identification of differentially compartmentalized proteins will reveal candidate molecules underlying various vitreoretinal diseases.

This video shows an effective technique for differentiating and dissecting the various semi-transparent structures of the human vitreous body in post mortem eyes.

The vitreous is an optically clear, collagenous extracellular matrix that fills the inside of the eye and overlies the retina. 1,2 Abnormal interactions ...

The Use of Primary Human Fibroblasts for Monitoring Mitochondrial Phenotypes in the Field of Parkinson's Disease

Parkinson's disease (PD) is the second most common movement disorder and affects 1% of people over the age of 60 1. Because ageing is the most important risk factor, cases of PD will increase during the next decades 2. Next to pathological protein folding and impaired protein degradation pathways, alterations of mitochondrial function and morphology were pointed out as further hallmark of neurodegeneration in PD 3-11.
After years of research in murine and human cancer cells as in vitro models to dissect molecular pathways of Parkinsonism, the use of human fibroblasts from patients and appropriate controls as ex vivo models has become a valuable research tool, if potential caveats are considered. Other than immortalized, rather artificial cell models, primary fibroblasts from patients carrying disease-associated mutations apparently reflect important pathological features of the human disease.
Here we delineate the procedure of taking skin biopsies, culturing human fibroblasts and using detailed protocols for essential microscopic techniques to define mitochondrial phenotypes. These were used to investigate different features associated with PD that are relevant to mitochondrial function and dynamics. Ex vivo, mitochondria can be analyzed in terms of their function, morphology, colocalization with lysosomes (the organelles degrading dysfunctional mitochondria) and degradation via the lysosomal pathway. These phenotypes are highly relevant for the identification of early signs of PD and may precede clinical motor symptoms in human disease-gene carriers. Hence, the assays presented here can be utilized as valuable tools to identify pathological features of neurodegeneration and help to define new therapeutic strategies in PD.

The Use of Primary Human Fibroblasts for Monitoring Mitochondrial Phenotypes in the Field of Parkinson&#039;s Disease

Fibroblasts from patients carrying mutations in Parkinson's disease-causing genes represent an easily accessible ex vivo model to study disease-associated phenotypes. Live cell imaging gives the opportunity to study morphological and functional parameters in living cells. Here we describe the preparation of human fibroblasts and subsequent monitoring of mitochondrial phenotypes.

Parkinson's disease (PD) is the second most  common movement disorder and affects 1% of people over the age of 60 1. Because ageing is  the most important ...

High Throughput Sequential ELISA for Validation of Biomarkers of Acute Graft-Versus-Host Disease

Unbiased discovery proteomics strategies have the potential to identify large numbers of novel biomarkers that can improve diagnostic and prognostic testing in a clinical setting and may help guide therapeutic interventions. When large numbers of candidate proteins are identified, it may be difficult to validate candidate biomarkers in a timely and efficient fashion from patient plasma samples that are event-driven, of finite volume and irreplaceable, such as at the onset of acute graft-versus-host disease (GVHD), a potentially life-threatening complication of allogeneic hematopoietic stem cell transplantation (HSCT).
Here we describe the process of performing commercially available ELISAs for six validated GVHD proteins: IL-2R&alpha;5, TNFR16, HGF7, IL-88, elafin2, and REG3&alpha;3 (also known as PAP1) in a sequential fashion to minimize freeze-thaw cycles, thawed plasma time and plasma usage. For this procedure we perform the ELISAs in sequential order as determined by sample dilution factor as established in our laboratory using manufacturer ELISA kits and protocols with minor adjustments to facilitate optimal sequential ELISA performance. The resulting plasma biomarker concentrations can then be compiled and analyzed for significant findings within a patient cohort. While these biomarkers are currently for research purposes only, their incorporation into clinical care is currently being investigated in clinical trials.
This technique can be applied to perform ELISAs for multiple proteins/cytokines of interest on the same sample(s) provided the samples do not need to be mixed with other reagents. If ELISA kits do not come with pre-coated plates, 96-well half-well plates or 384-well plates can be used to further minimize use of samples/reagents.

High throughput validation of multiple candidate biomarkers can be performed by sequential ELISA in order to minimize freeze/thaw cycles and use of precious plasma samples. Here, we demonstrate how to sequentially perform ELISAs for six different validated plasma biomarkers1-3 of graft-versus-host disease (GVHD)4 on the same plasma sample.

Unbiased discovery proteomics strategies have  the potential to identify large numbers of novel biomarkers that can improve  diagnostic and prognostic ...

High-throughput Flow Cytometry Cell-based Assay to Detect Antibodies to N-Methyl-D-aspartate Receptor or Dopamine-2 Receptor in Human Serum

Over the recent years, antibodies against surface and conformational proteins involved in neurotransmission have been detected in autoimmune CNS diseases in children and adults. These antibodies have been used to guide diagnosis and treatment. Cell-based assays have improved the detection of antibodies in patient serum. They are based on the surface expression of brain antigens on eukaryotic cells, which are then incubated with diluted patient sera followed by fluorochrome-conjugated secondary antibodies. After washing, secondary antibody binding is then analyzed by flow cytometry. Our group has developed a high-throughput flow cytometry live cell-based assay to reliably detect antibodies against specific neurotransmitter receptors. This flow cytometry method is straight forward, quantitative, efficient, and the use of a high-throughput sampler system allows for large patient cohorts to be easily assayed in a short space of time. Additionally, this cell-based assay can be easily adapted to detect antibodies to many different antigenic targets, both from the central nervous system and periphery. Discovering additional novel antibody biomarkers will enable prompt and accurate diagnosis and improve treatment of immune-mediated disorders.

Over the recent years, live cell-based assays have been used successfully to detect antibodies against surface and conformational antigens. Here, we describe a method using high-throughput flow cytometry enabling the analysis of large cohorts of patients. Detection of novel antibodies will improve diagnosis and treatment of immune-mediated disorders.

Over the recent years, antibodies against surface and conformational proteins involved in neurotransmission have been detected in autoimmune CNS diseases ...

Network Analysis of the Default Mode Network Using Functional Connectivity MRI in Temporal Lobe Epilepsy

Functional connectivity MRI (fcMRI) is an fMRI method that examines the connectivity of different brain areas based on the correlation of BOLD signal fluctuations over time. Temporal Lobe Epilepsy (TLE) is the most common type of adult epilepsy and involves multiple brain networks. The default mode network (DMN) is involved in conscious, resting state cognition and is thought to be affected in TLE where seizures cause impairment of consciousness. The DMN in epilepsy was examined using seed based fcMRI. The anterior and posterior hubs of the DMN were used as seeds in this analysis. The results show a disconnection between the anterior and posterior hubs of the DMN in TLE during the basal state. In addition, increased DMN connectivity to other brain regions in left TLE along with decreased connectivity in right TLE is revealed. The analysis demonstrates how seed-based fcMRI can be used to probe cerebral networks in brain disorders such as TLE.

The Default Mode Network (DMN) in Temporal Lobe Epilepsy (TLE) is analyzed in the resting state of the brain using seed-based functional connectivity MRI (fcMRI).

Functional connectivity MRI (fcMRI) is an fMRI method that examines the connectivity of different brain areas based on the correlation of BOLD signal ...

Collection, Isolation, and Flow Cytometric Analysis of Human Endocervical Samples

Despite the public health importance of mucosal pathogens (including HIV), relatively little is known about mucosal immunity, particularly at the female genital tract (FGT). Because heterosexual transmission now represents the dominant mechanism of HIV transmission, and given the continual spread of sexually transmitted infections (STIs), it is critical to understand the interplay between host and pathogen at the genital mucosa. The substantial gaps in knowledge around FGT immunity are partially due to the difficulty in successfully collecting and processing mucosal samples. In order to facilitate studies with sufficient sample size, collection techniques must be minimally invasive and efficient. To this end, a protocol for the collection of cervical cytobrush samples and subsequent isolation of cervical mononuclear cells (CMC) has been optimized. Using ex vivo flow cytometry-based immunophenotyping, it is possible to accurately and reliably quantify CMC lymphocyte/monocyte population frequencies and phenotypes. This technique can be coupled with the collection of cervical-vaginal lavage (CVL), which contains soluble immune mediators including cytokines, chemokines and anti-proteases, all of which can be used to determine the anti- or pro-inflammatory environment in the vagina.

The use of cytobrush sampling to collect lymphocytes and monocytes from the endocervix is a minimally invasive technique that provides samples for analysis of female genital tract immunity. In this protocol, we describe the collection of cytobrush samples and immune cell isolation for flow cytometry assays.

Despite the public health importance of mucosal pathogens (including HIV), relatively little is known about mucosal immunity, particularly at the female ...

Functional Human Liver Preservation and Recovery by Means of Subnormothermic Machine Perfusion

There is currently a severe shortage of liver grafts available for transplantation. Novel organ preservation techniques are needed to expand the pool of donor livers. Machine perfusion of donor liver grafts is an alternative to traditional cold storage of livers and holds much promise as a modality to expand the donor organ pool. We have recently described the potential benefit of subnormothermic machine perfusion of human livers. Machine perfused livers showed improving function and restoration of tissue ATP levels. Additionally, machine perfusion of liver grafts at subnormothermic temperatures allows for objective assessment of the functionality and suitability of a liver for transplantation. In these ways a great many livers that were previously discarded due to their suboptimal quality can be rescued via the restorative effects of machine perfusion and utilized for transplantation. Here we describe this technique of subnormothermic machine perfusion in detail. Human liver grafts allocated for research are perfused via the hepatic artery and portal vein with an acellular oxygenated perfusate at 21 &#176;C.

We describe a method of ex vivo machine perfusion of human liver grafts at subnormothermic temperature (21 &#176;C).

There is currently a severe shortage of liver grafts available for transplantation.  Novel organ preservation techniques are needed to expand the pool of ...

Detecting Anastasis In Vivo by CaspaseTracker Biosensor

Anastasis (Greek for &#8220;rising to life&#8221;) is a recently discovered cell recovery phenomenon whereby dying cells can reverse late-stage cell death processes that are generally assumed to be intrinsically irreversible. Promoting anastasis could in principle rescue or preserve injured cells that are difficult to replace such as cardiomyocytes or neurons, thereby facilitating tissue recovery. Conversely, suppressing anastasis in cancer cells, undergoing apoptosis after anti-cancer therapies, may ensure cancer cell death and reduce the chances of recurrence. However, these studies have been hampered by the lack of tools for tracking the fate of cells that undergo anastasis in live animals. The challenge is to identify the cells that have reversed the cell death process despite their morphologically normal appearance after recovery. To overcome this difficulty, we have developed Drosophila and mammalian CaspaseTracker biosensor systems that can identify and permanently track the anastatic cells in vitro or in vivo. Here, we present in vivo protocols for the generation and use of the CaspaseTracker dual biosensor system to detect and track anastasis in Drosophila melanogaster after transient exposure to cell death stimuli. While conventional biosensors and protocols can label cells actively undergoing apoptotic cell death, the CaspaseTracker biosensor can permanently label cells that have recovered after caspase activation - a hallmark of late-stage apoptosis, and simultaneously identify active apoptotic processes. This biosensor can also track the recovery of the cells that attempted other forms of cell death that directly or indirectly involved caspase activity. Therefore, this protocol enables us to continuously track the fate of these cells and their progeny, facilitating future studies of the biological functions, molecular mechanisms, physiological and pathological consequences, and therapeutic implications of anastasis. We also discuss the appropriate controls to distinguish cells that undergo anastasis from those that display non-apoptotic caspase activity in vivo.

Detecting Anastasis In Vivo by CaspaseTracker Biosensor

Anastasis is technically challenging to detect in vivo because the cells that have reversed the cell death process can be morphologically indistinguishable from normal healthy cells. Here we describe protocols for detecting and tracking cells that undergo anastasis in live animals by using our newly developed in vivo CaspaseTracker biosensor system.

Anastasis (Greek for &#8220;rising to life&#8221;) is a recently discovered cell recovery phenomenon whereby dying cells can reverse late-stage cell death ...

Simultaneous Flow Cytometric Characterization of Multiple Cell Types Retrieved from Mouse Brain/Spinal Cord Through Different Homogenization Methods

Recent advances in viral vector and nanomaterial sciences have opened the way for new cutting-edge approaches to investigate or manipulate the central nervous system (CNS). However, further optimization of these technologies would benefit from methods allowing rapid and streamline determination of the extent of CNS and cell-specific targeting upon administration of viral vectors or nanoparticles in the body. Here, we present a protocol that takes advantage of the high throughput and multiplexing capabilities of flow cytometry to allow a straightforward quantification of different cell subtypes isolated from mouse brain or spinal cord, namely microglia/macrophages, lymphocytes, astrocytes, oligodendrocytes, neurons and endothelial cells. We apply this approach to highlight critical differences between two tissue homogenization methods in terms of cell yield, viability and composition. This could instruct the user to choose the best method depending on the cell type(s) of interest and the specific application. This method is not suited for analysis of anatomical distribution, since the tissue is homogenized to generate a single-cell suspension. However, it allows to work with viable cells and it can be combined with cell-sorting, opening the way for several applications that could expand the repertoire of tools in the hands of the neuroscientist, ranging from establishment of primary cultures derived from pure cell populations, to gene-expression analyses and biochemical or functional assays on well-defined cell subtypes in the context of neurodegenerative diseases, upon pharmacological treatment or gene therapy.

We present a flow cytometry method to identify simultaneously different cell types retrieved from mouse brain or spinal cord. This method could be exploited to isolate or characterize pure cell populations in neurodegenerative diseases or to quantify the extent of cell targeting upon in vivo administration of viral vectors or nanoparticles.

Recent advances in viral vector and nanomaterial sciences have opened the way for new cutting-edge approaches to investigate or manipulate the central ...

3D Planning and Printing of Patient Specific Implants for Reconstruction of Bony Defects

We are in the midst of the 3D era in most aspects of life, and especially in medicine. The surgical discipline is one of the major players in the medical field using the constantly developing 3D planning and printing capabilities. Computer-assisted design (CAD) and computer assisted manufacturing (CAM) are used to describe the 3D planning and manufacturing of the product. The planning and manufacturing of 3D surgical guides and reconstruction implants is performed almost exclusively by engineers. As technology advances and software interfaces become more user-friendly, it raises a question regarding the possibility of transferring the planning and manufacturing to the clinician. The reasons for such a shift are clear: the surgeon has the idea of what he wants to design, and he also knows what is feasible and could be used in the operating room. It allows him to be prepared for any scenario/unexpected results during the operation and allows the surgeon to be creative and express his new ideas using the CAD software. The purpose of this method is to provide clinicians with the ability to create their own surgical guides and reconstruction implants. In this manuscript, a detailed protocol will provide a simple method for segmentation using segmentation software and implant planning using a 3D design software. Following the segmentation and stl file production using segmentation software, the clinician could create a simple patient specific reconstruction plate or a more complex plate with a cradle for bone graft positioning. Surgical guides can be created for accurate resection, hole preparation for proper reconstruction plate positioning or for bone graft harvesting and re-contouring. A case of lower jaw reconstruction following plate fracture and nonunion healing of a trauma sustained injury is detailed.

This protocol describes the use of 3D planning and printing for reconstruction of bony defects. We use segmentation tools to create 3D models followed by 3D design software to create patient specific implants for reconstruction purposes concomitant to ablative surgery or as a second stage.

We are in the midst of the 3D era in most aspects of life, and especially in medicine. The surgical discipline is one of the major players in the medical ...