This work was supported by grants from the Swiss National Science Foundation (310030_162579/1 to Brenda Renata Kwak and 320030_144150 to Pierre Fontana) as well as by a grant from the Swiss Heart Foundation.

Five unrelated healthy volunteers were recruited for blood sampling for platelet isolation and aggregation tests. Written informed consent was obtained and the protocol was approved by the Central Ethics Committee of the Geneva University Hospitals. All volunteers certified to be healthy and to have not taken any platelet-interfering drugs during at least the 10 days preceding the experiments.
1. Buffer Preparation for Human Blood Collection and Washed Platelet Isolation
<ol>
	<li>Prepare a 100 mL aqueous solution of acid-citrate-dextrose (ACD) by dissolving 1.4 g citric acid monohydrate (C6H8O7&#8226;H2O, 66.6 mM), 2.5 g trisodium citrate dihydrate (Na3C6H5O7&#8226;2 H2O, 85 mM) and 2 g of anhydrous D(+)-glucose. The pH of the solution is about 4.5.</li>
	<li>Prepare stock solutions for Tyrode&#39;s buffer as follows
	<ol>
		<li>Prepare stock solution 1 by dissolving 80 g NaCl, 2 g KCl, 10 g NaHCO3 and 0.58 g NaH2PO4*H2O in 500 mL of distilled H2O. The respective final concentrations are 2.73 M, 53.6 mM, 238 mM and 8.4 mM. Keep the solution at 4 &#176;C.</li>
		<li>Prepare stock solution 2 by dissolving 10.15 g MgCl2*6 H2O (100 mM) in 500 mL distilled H2O. Keep solution at 4 &#176;C.</li>
		<li>Prepare stock solution 3 by dissolving 10.95 g (100 mM) CaCl2*6 H2O in 500 mL distilled H2O. Keep solution at 4 &#176;C.</li>
	</ol>
	</li>
	<li>Prepare Tyrode&#39;s buffer by diluting 2.5 mL of stock solution 1 in a final volume of 50 mL with distilled H2O. This corresponds to final concentrations of 136.5 mM NaCl, 2.68 mM KCl, 11.9 mM NaHCO3 and 0.42 mM NaH2PO4*H2O. Adjust the pH to 7.35 and sterilize by filtering with 0.22-&#956;m filters.</li>
	<li>Prepare Tyrode&#39;s albumin 0.35% buffer (TA buffer7) by diluting 5 mL of stock solution 1, 1 mL of stock solution 2, 2 mL of stock solution 3, 0.5 mL 1M HEPES, 1.8 mL of 200 g/L human serum albumin and 0.1 g of anhydrous D(+)-glucose in a final volume of 100 mL distilled H2O.
	<ol>
		<li>Adjust the pH to 7.35 with 1N HCl and set the osmolarity to 295 mOsm/L by adding distilled H2O (10% of total volume). Final concentrations in this solution are: 124 mM NaCl, 2.44 mM KCl, 10.82 mM NaHCO3, 0.38 mM NaH2PO4*H2O, 0.91 mM MgCl2*6 H2O, 1.82 mM CaCl2*6 H2O. Keep TA buffer at 37 &#176;C during the whole experiment.</li>
	</ol>
	</li>
</ol>
2. Blood Collection
<ol>
	<li>Collect 45-50 mL of venous blood, from the antecubital vein using a 19 G needle and no or low tourniquet, into 50 mL tubes containing ACD anticoagulant (1 volume ACD for 6 volumes of blood). Discard the first 1-2 mL of blood to avoid the presence of thrombin and tissue factor.
	<ol>
		<li>After collection, mix the blood with the ACD by gently inverting the tube. Incubate the sample for 10 min at 37 &#176;C.</li>
	</ol>
	</li>
</ol>
3. Preparation of Human Washed Platelets
<ol>
	<li>Pre-heat the centrifuge to 37 &#176;C. All centrifugation steps below are performed at this temperature.</li>
	<li>Dispatch the collected blood into 15 mL tubes (5 mL per tube) and centrifuge at 250 x g for 13 min to obtain PRP. 
	NOTE: This centrifugation step results in the production of three layers in the sample: 1) The upper layer, composed of plasma, platelets, and a small fraction of white blood cells. 2) The intermediate layer, a portion rich in white blood cells. 3) The bottom layer, which is essentially composed of red blood cells.</li>
	<li>Collect the PRP by pipetting the upper layer carefully into a new 15 mL tube to maximally prevent contamination with red and white blood cells, and incubate for 10 min at 37 &#176;C.</li>
	<li>Centrifuge the PRP at 2,200 x g for 12 min (for 5 mL PRP). 
	NOTE: This centrifugation step should be performed with low brake or without brake.</li>
	<li>Remove the supernatant (platelet-poor plasma), and carefully resuspend the pellet with 10 mL of TA buffer containing 2 &#181;L/mL of heparin (5,000 U/mL) and 2.5 &#181;L/mL of 25 &#956;M PGI2 using a plastic Pasteur pipet. Incubate for 10 min at 37 &#176;C.</li>
	<li>Add 2.5 &#181;L/mL of 25 &#956;M PGI2 and centrifuge for 8 min at 1,900 x g (with low brake or without brake).</li>
	<li>Remove the supernatant and resuspend the pellet with 5 mL TA buffer containing 2.5 &#181;L/mL of 25 &#956;M PGI2 using a plastic Pasteur pipet. Incubate for 10 min at 37 &#176;C.</li>
	<li>During the incubation period, pipet 150 &#181;L of the platelet suspension into a 1.5 mL tube and count platelets, using an automatized cell counter (that detects the size of blood cells by measuring the changes in direct-current resistance).</li>
	<li>After the 10 min incubation, add 2.5 &#181;L/mL of 25 &#956;M PGI2 to the platelet suspension and immediately centrifuge at 1,900 x g for 8 min.</li>
	<li>Remove the supernatant and resuspend the pellet to a concentration of 250,000 platelets/&#181;L with an adequate volume of TA buffer (i.e. if the cell count is 500,000 per &#181;L, resuspend in 10 mL TA buffer) containing 32 &#181;L/mL of apyrase at 0.01 U/mL (final concentration 0.32 U/mL). 
	NOTE: High concentration of apyrase is used to avoid the desensitization of P2X1 receptors induced by spontaneous secretion of ATP10,11 in absence of agonists. This is important because collagen-induced responses are induced by fast paracrine/autocrine activation of P2X1 by ATP released from activated platelets. If the platelet signaling pathway does not critically require preservation of P2X1 function, use 0.02 U/mL apyrase. Several studies (reviewed in Mahaut-Smith et al.10) demonstrated that 0.02 U/mL apyrase avoids ADP receptor P2Y1 desensitization with negligible P2X1 responses.</li>
	<li>Incubate the cell suspension for at least 30 min at 37 &#176;C before performing the aggregometric measurements. The preparation is stable for 5 to 8 h.</li>
</ol>
4. Aggregometry
<ol>
	<li>Prepare fibrinogen (56 mg/mL) in Tyrode&#39;s buffer.</li>
	<li>Pipet 260 &#181;L of platelet suspension into glass cuvettes (Figure 1A; left cuvette) containing 10 &#181;L of fibrinogen (56 mg/mL) and a magnetic stirring rod, then incubate the suspension for 2 - 3 min at 37 &#176;C in incubation wells present in the aggregometer (Figure 1B and 1C).</li>
	<li>Pre-incubate with the Panx1 inhibitor Brilliant Blue FCF by adding 10 &#181;L of a 2.8 mM or 28 mM stock solution (final concentration 100 &#956;M and 1 mM, respectively) for 7 min at 37 &#176;C.</li>
	<li>Calibrate the aggregometer to an assumptive 100% aggregation value by measuring the OD of a cuvette containing 10 &#181;L fibrinogen (56 mg/mL), 10 &#181;L Brilliant Blue FCF (2.8 mM or 28 mM) and TA buffer without platelets.
	<ol>
		<li>Place the cuvette in an aggregation well under automatic stirring and press the corresponding button on the keyboard of the computer linked to the aggregometer (i.e. press F1 if aggregation well 1 is used). 
		NOTE: This experiment described below includes Brilliant Blue FCF. The compound used for calibration has to be adjusted to the experimental condition.</li>
	</ol>
	</li>
	<li>Calibrate the aggregometer to an assumptive 0% aggregation value by using the same platelet sample that will be used for the experiment under automatic stirring.
	<ol>
		<li>Place the cuvette in the aggregation well and press the corresponding button on the keyboard of the computer linked to the aggregometer. Wait for about 20-30 s before proceeding. This delay serves to assure that no aggregation happens before adding the agonists. 
		NOTE: As any difference in platelet number may have an effect on the measured OD, the 0% calibration step needs to be repeated for each individual measurement.</li>
	</ol>
	</li>
	<li>Add 20 &#181;L of desired agonist, such as 15 &#181;g/mL collagen (1 &#181;g/mL final) or 1.125 mM arachidonic acid (75 &#181;M final), into the cuvette. Immediately start the recording under continuous automatic stirring by pressing the corresponding button on the keyboard of the computer linked to the aggregometer. 
	NOTE: The addition of the agonist induces platelet activation. Platelet aggregates can clearly be distinguished in the glass cuvette at the end of the experiment (Figure 1A; right cuvette).</li>
	<li>The recording automatically stops after 6 min. At this point, save the data by clicking on the save icon of the computer. 
	NOTE: The calculation of the rate of aggregation is performed by the computer, which expresses the end results of the aggregation process as a percentage.</li>
	<li>Analyze the data.
	<ol>
		<li>For additional extensive information on protocols for the preparation of washed platelets suspensions and turbidimetric measurement of platelet aggregation, refer to other papers authored by experts in the field12,13.</li>
	</ol>
	</li>
</ol>

<ol>
	<li>Patel, S. R., Hartwig, J. H., Italiano, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+biogenesis+of+platelets+from+megakaryocyte+proplatelets.">The biogenesis of platelets from megakaryocyte proplatelets.</a> J Clin Invest. 115 (12), 3348-3354 (2005).</li><li>Andrews, R. K., Berndt, M. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Platelet+physiology+and+thrombosis.">Platelet physiology and thrombosis.</a> Thromb Res. 114 (5-6), 447-453 (2004).</li><li>Go, A. 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=Heart+disease+and+stroke+statistics--2014+update:+a+report+from+the+American+Heart+Association.">Heart disease and stroke statistics--2014 update: a report from the American Heart Association.</a> Circulation. 129 (3), e28-e292 (2014).</li><li>Creager, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Results+of+the+CAPRIE+trial:+efficacy+and+safety+of+clopidogrel.+Clopidogrel+versus+aspirin+in+patients+at+risk+of+ischaemic+events.">Results of the CAPRIE trial: efficacy and safety of clopidogrel. Clopidogrel versus aspirin in patients at risk of ischaemic events.</a> Vasc Med. 3 (3), 257-260 (1998).</li><li>Born, G. V., Cross, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Aggregation+of+Blood+Platelets.">The Aggregation of Blood Platelets.</a> J Physiol. 168, 178-195 (1963).</li><li>Cazenave, J. P., Hemmendinger, S., Beretz, A., Sutter-Bay, A., Launay, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=[Platelet+aggregation:+a+tool+for+clinical+investigation+and+pharmacological+study+Methodology].">[Platelet aggregation: a tool for clinical investigation and pharmacological study Methodology].</a> Ann Biol Clin (Paris). 41 (3), 167-179 (1983).</li><li>Molica, F., 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=Functional+role+of+a+polymorphism+in+the+Pannexin1+gene+in+collagen-induced+platelet+aggregation.">Functional role of a polymorphism in the Pannexin1 gene in collagen-induced platelet aggregation.</a> Thromb Haemost. 114 (2), 325-336 (2015).</li><li>Taylor, K. A., Wright, J. R., Vial, C., Evans, R. J., Mahaut-Smith, M. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Amplification+of+human+platelet+activation+by+surface+pannexin-1+channels.">Amplification of human platelet activation by surface pannexin-1 channels.</a> J Thromb Haemost. 12 (6), 987-998 (2014).</li><li>Wang, J., Jackson, D. G., Dahl, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+food+dye+FD&amp;C+Blue+No.+1+is+a+selective+inhibitor+of+the+ATP+release+channel+Panx1.">The food dye FD&amp;C Blue No. 1 is a selective inhibitor of the ATP release channel Panx1.</a> J Gen Physiol. 141 (5), 649-656 (2013).</li><li>Mahaut-Smith, M. P., Jones, S., Evans, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+P2X1+receptor+and+platelet+function.">The P2X1 receptor and platelet function.</a> Purinergic Signal. 7 (3), 341-356 (2011).</li><li>Hechler, 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=Inhibition+of+platelet+functions+and+thrombosis+through+selective+or+nonselective+inhibition+of+the+platelet+P2+receptors+with+increasing+doses+of+NF449+[4,4',4'',4'''-(carbonylbis(imino-5,1,3-benzenetriylbis-(carbonylimino)))tetrakis+-benzene-1,3-disulfonic+acid+octasodium+salt].">Inhibition of platelet functions and thrombosis through selective or nonselective inhibition of the platelet P2 receptors with increasing doses of NF449 [4,4',4'',4'''-(carbonylbis(imino-5,1,3-benzenetriylbis-(carbonylimino)))tetrakis -benzene-1,3-disulfonic acid octasodium salt].</a> J Pharmacol Exp Ther. 314 (1), 232-243 (2005).</li><li>Cazenave, J. P., 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=Preparation+of+washed+platelet+suspensions+from+human+and+rodent+blood.">Preparation of washed platelet suspensions from human and rodent blood.</a> Methods Mol Biol. 272, 13-28 (2004).</li><li>Jarvis, G. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Platelet+aggregation:+turbidimetric+measurements.">Platelet aggregation: turbidimetric measurements.</a> Methods Mol Biol. 272, 65-76 (2004).</li><li>Thompson, N. T., Scrutton, M. C., Wallis, R. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Particle+volume+changes+associated+with+light+transmittance+changes+in+the+platelet+aggregometer:+dependence+upon+aggregating+agent+and+effectiveness+of+stimulus.">Particle volume changes associated with light transmittance changes in the platelet aggregometer: dependence upon aggregating agent and effectiveness of stimulus.</a> Thromb Res. 41 (5), 615-626 (1986).</li><li>Malinski, J. A., Nelsestuen, G. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Relationship+of+turbidity+to+the+stages+of+platelet+aggregation.">Relationship of turbidity to the stages of platelet aggregation.</a> Biochim Biophys Acta. 882 (2), 177-182 (1986).</li><li>Riess, H., Braun, G., Brehm, G., Hiller, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Critical+evaluation+of+platelet+aggregation+in+whole+human+blood.">Critical evaluation of platelet aggregation in whole human blood.</a> Am J Clin Pathol. 85 (1), 50-56 (1986).</li><li>Hayward, C. P., 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=An+evaluation+of+methods+for+determining+reference+intervals+for+light+transmission+platelet+aggregation+tests+on+samples+with+normal+or+reduced+platelet+counts.">An evaluation of methods for determining reference intervals for light transmission platelet aggregation tests on samples with normal or reduced platelet counts.</a> Thromb Haemost. 100 (1), 134-145 (2008).</li><li>Frelinger, A. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Platelet+function+tests,+independent+of+platelet+count,+are+associated+with+bleeding+severity+in.">Platelet function tests, independent of platelet count, are associated with bleeding severity in.</a> ITP. Blood. 126 (7), 873-879 (2015).</li><li>Fusegawa, Y., Goto, S., Handa, S., Kawada, T., Ando, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Platelet+spontaneous+aggregation+in+platelet-rich+plasma+is+increased+in+habitual+smokers.">Platelet spontaneous aggregation in platelet-rich plasma is increased in habitual smokers.</a> Thromb Res. 93 (6), 271-278 (1999).</li><li>Davis, R. B., Boyd, D. G., McKinney, M. E., Jones, C. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+exercise+and+exercise+conditioning+on+blood+platelet+function.">Effects of exercise and exercise conditioning on blood platelet function.</a> Med Sci Sports Exerc. 22 (1), 49-53 (1990).</li><li>Yee, D. L., Sun, C. W., Bergeron, A. L., Dong, J. F., Bray, P. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Aggregometry+detects+platelet+hyperreactivity+in+healthy+individuals.">Aggregometry detects platelet hyperreactivity in healthy individuals.</a> Blood. 106 (8), 2723-2729 (2005).</li><li>Cattaneo, M., 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=Recommendations+for+the+Standardization+of+Light+Transmission+Aggregometry:+A+Consensus+of+the+Working+Party+from+the+Platelet+Physiology+Subcommittee+of+SSC/ISTH.">Recommendations for the Standardization of Light Transmission Aggregometry: A Consensus of the Working Party from the Platelet Physiology Subcommittee of SSC/ISTH.</a> J Thromb Haemost. , (2013).</li><li>Patel, D., Zhang, X., Veenstra, 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=Connexin+hemichannel+and+pannexin+channel+electrophysiology:+how+do+they+differ?.">Connexin hemichannel and pannexin channel electrophysiology: how do they differ?.</a> FEBS Lett. 588 (8), 1372-1378 (2014).</li><li>European Food Safety Authority. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Scientific+Opinion+on+the+re-evaluation+of+Brilliant+Blue+FCF+(E+133)+as+a+food+additive.">Scientific Opinion on the re-evaluation of Brilliant Blue FCF (E 133) as a food additive.</a> EFSA Journal. 8 (11), 1853-1889 (2010).</li><li>Lages, B., Scrutton, M. C., Holmsen, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Studies+on+gel-filtered+human+platelets:+isolation+and+characterization+in+a+medium+containing+no+added+Ca2+,+Mg2+,+or+K+.">Studies on gel-filtered human platelets: isolation and characterization in a medium containing no added Ca2+, Mg2+, or K+.</a> J Lab Clin Med. 85 (5), 811-825 (1975).</li></ol>

The authors have nothing to disclose.

There is great interest in finding new drugs capable of modulating platelet function in order to prevent thrombosis without enhancing the risk of bleeding. For this purpose, in vitro laboratory tests which can reliably and reproducibly monitor aggregation responses in human platelets are absolutely necessary. Turbidimetric aggregometry is an easy technique to perform. However, some precautions need to be kept in mind. The measurements need to be performed under continuous stirring as the aggregation process is l...

Platelets are crucial components of blood and their main function-together with coagulation factors-is to stop bleeding after blood vessel injury. Platelets are small (2-3 &#181;m) anuclear fragments derived from megakaryocytes of the bone marrow1. Platelets circulate in non-activated state, during which they appear as lens-shaped structures. Upon interruption of the endothelium, platelets gather to the site of blood vessel injury to plug the hole, a process called primary hemostasis. Initially, platelets attach to sub-endothelial molecules, such as collagen and von Willebrand factor, that are exposed as a result of the injury-adhesion step2. Then, they change shape and secrete chemical messengers-activation step. Finally, they connect to each other by bridging receptors-aggregation step. Primary hemostasis is followed by a secondary process involving activation of the coagulation cascade with fibrin deposition, which stabilizes the initial thrombus2.
Acute ischemic events such as myocardial infarction3 often result from thrombi that form because of physical disruption (rupture) of an atherosclerotic plaque. Current anti-platelet drugs are the cornerstone of the treatment of this widespread disease but their clinical benefit is limited by an increased risk for bleeding. The most prescribed drugs in cardiovascular patients, aspirin and anti-P2Y12 compounds, target the thromboxane A2 and the ADP pathways4, respectively, which are the major pathways leading to platelet activation. However, innovative research towards new targets that would optimally balance antithrombotic effects and haemorragic risk is still necessary.
From the 1960s5 to today, turbidimetric aggregometry has played a crucial role in research, enhancing our knowledge of platelet reactivity and in the monitoring of the potency of anti-thrombotic reagents in humans. Turbidimetry was initially applied to PRP extracted from blood samples. Indeed, blood collection performed in tubes containing citrate allows fast and large production of PRP without having any effect on platelet integrity and function. However, the short-term stability (about 3 h) of PRP and the remaining plasmatic enzymes, such as thrombin, and the low calcium concentration associated with potentially artefactual aggregation profiles are of major inconvenience for the use of PRP. An important step forward has been the development of a method for platelet isolation with additional centrifugation and washing steps6. In short, PRP is isolated from whole blood collected on acid-citrate-dextrose (ACD) and platelets are isolated after serial centrifugation steps before being resuspended in an iso-osmotic phosphate buffer (Tyrode&#39;s buffer) containing glucose, human serum albumin and divalent cations (Ca2+ and Mg2+). To avoid changes in platelet reactivity, the pH of Tyrode&#39;s buffer is carefully kept at 7.35-7.4. Moreover, undesired activation of platelets is prevented by adding prostacyclin (PGI2) before some centrifugation steps. Finally, addition of apyrase prevents washed platelets from becoming resistant against the action of ATP/ADP. The resulting platelet suspension lacks coagulant factors and the stability of platelets is increased by at least two-fold as compared to PRP solutions. In addition, the fact that platelets are inactive but intact warrants the reproducibility of turbidimetric measurements and provides the ability to study the action of agonists or antagonists of platelet aggregation in an optimal way.
Using this method, we have shown in a recent study that inhibiting the formation of Panx1 channels by a genetic approach (knock-out mice) or decreasing Panx1 channel activity by pharmacological approaches reduced collagen-induced platelet aggregation7. Panx1 forms ATP-release channels, which are ubiquitously expressed in many cell types including human platelets7,8. In fact, we demonstrated by turbidimetry on human washed platelets that a 7 min preincubation with a panel of more-or-less specific chemical blockers (probenecid, mefloquine and 10Panx1 peptides) prior to the addition of various agonists, inhibited specifically collagen-induced platelet aggregation while platelet responses to AA and ADP were not affected. We demonstrated that ATP release through Panx1 channels specifically interferes in the GPVI signaling pathway leading to collagen-induced aggregation. Interestingly, multiple FDA-approved compounds with applications in other diseases (probenecid, mefloquine) affect the activity of Panx1 channels in platelets. On one hand, this opens new therapeutic perspectives to selectively modify platelet reactivity. On the other hand, one should consider potential secondary effects of these compounds. In this context, the safe food dye Brilliant Blue FCF used in multiple candies and energy drinks has been described as a selective inhibitor of Panx19. We describe here a protocol for the isolation of human washed platelets and turbidimetric measurements of platelet aggregation adapted to investigate the effect of the Brilliant Blue FCF dye as an antagonist of platelet aggregation.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>citric acid monohydrate (C6H8O7*H2O)</td>
			<td>Roth</td>
			<td>5949-29-1</td>
			<td>danger of eye damage/irritation</td>
		</tr>
		<tr>
			<td>trisodium citrate dihydrate (Na3C6H5O7*2H2O)</td>
			<td>Sigma-Aldrich</td>
			<td>S1804</td>
			<td>-</td>
		</tr>
		<tr>
			<td>D(+)-glucose</td>
			<td>Sigma-Aldrich</td>
			<td>G8270</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Sodium chloride (NaCl)</td>
			<td>Sigma-Aldrich</td>
			<td>S9888</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Potassium chloride (KCl)</td>
			<td>Sigma-Aldrich</td>
			<td>P9541</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Sodium bicarbonate (NaHCO3)</td>
			<td>Sigma-Aldrich</td>
			<td>S6014</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Sodium dihydrogenophosphate monohydrate (NaH2PO4*H2O)</td>
			<td>Sigma-Aldrich</td>
			<td>S9638</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Magnesium chloride hexahydrate (MgCl2*6H2O)</td>
			<td>Sigma-Aldrich</td>
			<td>M9272</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Calcium chloride hexahydrate (CaCl2*6H2O)</td>
			<td>Sigma-Aldrich</td>
			<td>442909</td>
			<td>danger of eye damage/irritation</td>
		</tr>
		<tr>
			<td>N-2-hydroxyethylpiperazine-N-2-ethane sulfonic acid (Hepes)</td>
			<td>ThermoFisher Scientific&#160;</td>
			<td>15630</td>
			<td>-</td>
		</tr>
		<tr>
			<td>human serum albumin</td>
			<td>CSL Behring</td>
			<td>00257/374</td>
			<td>-</td>
		</tr>
		<tr>
			<td>hydrochloric acid</td>
			<td>Sigma-Aldrich</td>
			<td>320331</td>
			<td>Corrosive and irritative for the respiratory system. Can cause severe skin and eye damages.</td>
		</tr>
		<tr>
			<td>Eppendorf 5810 R</td>
			<td>Fisher Scientific</td>
			<td>-</td>
			<td>-</td>
		</tr>
		<tr>
			<td>heparin</td>
			<td>Drosspharm AG/SA</td>
			<td>20810</td>
			<td></td>
		</tr>
		<tr>
			<td>prostacyclin I2 (PGI2)</td>
			<td>Cayman</td>
			<td>18220</td>
			<td>-</td>
		</tr>
		<tr>
			<td>apyrase from potatoes</td>
			<td>Sigma-Aldrich</td>
			<td>A6535</td>
			<td>-</td>
		</tr>
		<tr>
			<td>fibrinogen (Haemocomplettan)</td>
			<td>CSL Behring</td>
			<td>HS 73466011</td>
			<td>-</td>
		</tr>
		<tr>
			<td>thrombo-aggragometer SD-Medical</td>
			<td>SD-Innovation</td>
			<td>TA8V</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Brilliant blue FCF (Erioglaucine disodium salt)</td>
			<td>Sigma-Aldrich</td>
			<td>80717</td>
			<td>Harmful to aquatic life with long lasting effects (Avoid release to the environnement)</td>
		</tr>
		<tr>
			<td>collagen</td>
			<td>Horm, Nycomed</td>
			<td></td>
			<td>-</td>
		</tr>
		<tr>
			<td>arachidonic acid</td>
			<td>Bio/Data corporation</td>
			<td>C/N 101297</td>
			<td>-</td>
		</tr>
		<tr>
			<td>cell counter Sysmex KX-21N</td>
			<td>Sysmex Digitana&#160;</td>
			<td>-</td>
			<td>-</td>
		</tr>
		<tr>
			<td>HEPES</td>
			<td>Gibco</td>
			<td>15630-056</td>
			<td>-</td>
		</tr>
		<tr>
			<td>glass cuvettes</td>
			<td>SD-Innovation</td>
			<td>THCV1000</td>
			<td>-</td>
		</tr>
		<tr>
			<td>magnetic stirrers</td>
			<td>SD-Innovation</td>
			<td>THA100</td>
			<td>-</td>
		</tr>
	</tbody>
</table>

turbidimetry on human washed platelets: the effect of the pannexin1-inhibitor brilliant blue fcf on collagen-induced aggregation

Turbidimetry is a laboratory technique that is applied to measure the aggregation of platelets suspended in either plasma (platelet-rich plasma, PRP) or in buffer (washed platelets), by the use of one or a combination of agonists. The use of washed platelets separated from their plasma environment and in the absence of anticoagulants allows for studying intrinsic platelet properties. Among the large panel of agonists, arachidonic acid (AA), adenosine di-phosphate (ADP), thrombin and collagen are the most frequently used. The aggregation response is quantified by measuring the relative optical density (OD) over time of platelet suspension under continuous stirring. Platelets in homogeneous suspension limit the passage of light after the addition of an agonist, platelet shape change occurs producing a small transitory increase in OD. Following this initial activation step, platelet clots form gradually, allowing the passage of light through the suspension as a result of decreased OD. The aggregation process is ultimately expressed as a percentage, compared to the OD of platelet-poor plasma or buffer. Rigorous calibration is thus essential at the beginning of each experiment. As a general rule: calibration to 0% is set by measuring the OD of a non-stimulated platelet suspension while measuring the OD of the suspension medium containing no platelets represents a value of 100%. Platelet aggregation is generally visualized as a real-time aggregation curve. Turbidimetry is one of the most commonly used laboratory techniques for the investigation of platelet function and is considered as the historical gold standard and used for the development of new pharmaceutical agents aimed at inhibiting platelet aggregation. Here, we describe detailed protocols for 1) preparation of human washed platelets and 2) turbidimetric analysis of collagen-induced aggregation of human washed platelets pretreated with the food dye Brilliant Blue FCF that was recently identified as an inhibitor of Pannexin1 (Panx1) channels.

The aggregometer software automatically produces the aggregation curves and gives the values for maximal aggregation in percentage. The values can be copied to a data analysis software in order to perform statistical analysis and visualize maximal aggregation values in form of bar charts. Optionally, each individual point of the aggregation curves can be exported successively into a spreadsheet software and then to statistical software (e.g. GraphPad) in order to visualize the cu...

Watch this Scientific Journal Video about Turbidimetry on Human Washed Platelets: The Effect of the Pannexin1-inhibitor Brilliant Blue FCF on Collagen-induced Aggregation at JoVE.com

Turbidimetry on Human Washed Platelets: The Effect of the Pannexin1-inhibitor Brilliant Blue FCF on Collagen-induced Aggregation

We describe a straightforward method for the isolation of washed platelets from human blood followed by agonist-induced platelet aggregation measurements by turbidimetry. As an example we apply this method for studying the aggregation response of human platelets to collagen after a pre-incubation with the Pannexin1 channel inhibitor Brilliant Blue FCF.

Turbidimetry is a laboratory technique that is applied to measure the aggregation of platelets suspended in either plasma (platelet-rich plasma, PRP) or ...

turbidimetry-on-human-washed-platelets-effect-pannexin1-inhibitor

Research

JoVE Journal

Medicine

11.9K Views.  University of Geneva. We describe a straightforward method for the isolation of washed platelets from human blood followed by agonist-induced platelet aggregation measurements by turbidimetry. As an example we apply this method for studying the aggregation response of human platelets to collagen after a pre-incubation with the Pannexin1 channel inhibitor Brilliant Blue FCF.

Video: Turbidimetry on Human Washed Platelets: The Effect of the Pannexin1-inhibitor Brilliant Blue FCF on Collagen-induced Aggregation

A Contusive Model of Unilateral Cervical Spinal Cord Injury Using the Infinite Horizon Impactor

While the majority of human spinal cord injuries occur in the cervical spinal cord, the vast majority of laboratory research employs animal models of spinal cord injury (SCI) in which the thoracic spinal cord is injured. Additionally, because most human cord injuries occur as the result of blunt, non-penetrating trauma (e.g. motor vehicle accident, sporting injury) where the spinal cord is violently struck by displaced bone or soft tissues, the majority of SCI researchers are of the opinion that the most clinically relevant injury models are those in which the spinal cord is rapidly contused.1 Therefore, an important step in the preclinical evaluation of novel treatments on their way to human translation is an assessment of their efficacy in a model of contusion SCI within the cervical spinal cord. Here, we describe the technical aspects and resultant anatomical and behavioral outcomes of an unilateral contusive model of cervical SCI that employs the Infinite Horizon spinal cord injury impactor.
Sprague Dawley rats underwent a left-sided unilateral laminectomy at C5. To optimize the reproducibility of the biomechanical, functional, and histological outcomes of the injury model, we contused the spinal cords using an impact force of 150 kdyn, an impact trajectory of 22.5&deg; (animals rotated at 22.5&deg;), and an impact location off of midline of 1.4 mm. Functional recovery was assessed using the cylinder rearing test, horizontal ladder test, grooming test and modified Montoya's staircase test for up to 6 weeks, after which the spinal cords were evaluated histologically for white and grey matter sparing.
The injury model presented here imparts consistent and reproducible biomechanical forces to the spinal cord, an important feature of any experimental SCI model. This results in discrete histological damage to the lateral half of the spinal cord which is largely contained to the ipsilateral side of injury. The injury is well tolerated by the animals, but does result in functional deficits of the forelimb that are significant and sustained in the weeks following injury. The cervical unilateral injury model presented here may be a resource to researchers who wish to evaluate potentially promising therapies prior to human translation.

A reliable and repeatable way to produce a cervical unilateral spinal cord injury using the Infinite Horizon impactor is described. The method takes advantage of a custom designed frame and clamp to stabilize the spine. The standardized procedure and biomechanical injury parameters result in sufficient and sustained injuries.

While the majority of human spinal cord injuries occur in the cervical spinal cord, the vast majority of laboratory research employs animal models of ...

Immunohistochemical Staining of B7-H1 (PD-L1) on Paraffin-embedded Slides of Pancreatic Adenocarcinoma Tissue

B7-H1/PD-L1, a member of the B7 family of immune-regulatory cell-surface proteins, plays an important role in the negative regulation of cell-mediated immune responses through its interaction with its receptor, programmed death-1 (PD-1) 1,2. Overexpression of B7-H1 by tumor cells has been noted in a number of human cancers, including melanoma, glioblastoma, and carcinomas of the lung, breast, colon, ovary, and renal cells, and has been shown to impair anti-tumor T-cell immunity3-8.
Recently, B7-H1 expression by pancreatic adenocarcinoma tissues has been identified as a potential prognostic marker9,10. Additionally, blockade of B7-H1 in a mouse model of pancreatic cancer has been shown to produce an anti-tumor response11. These data suggest the importance of B7-H1 as a potential therapeutic target. Anti-B7-H1 blockade antibodies are therefore being tested in clinical trials for multiple human solid tumors including melanoma and cancers of lung, colon, kidney, stomach and pancreas12.
In order to eventually be able to identify the patients who will benefit from B7-H1 targeting therapies, it is critical to investigate the correlation between expression and localization of B7-H1 and patient response to treatment with B7-H1 blockade antibodies. Examining the expression of B7-H1 in human pancreatic adenocarcinoma tissues through immunohistochemistry will give a better understanding of how this co-inhibitory signaling molecule contributes to the suppression of antitumor immunity in the tumor's microenvironment. The anti-B7-H1 monoclonal antibody (clone 5H1) developed by Chen and coworkers has been shown to produce reliable staining results in cryosections of multiple types of human neoplastic tissues4,8, but staining on paraffin-embedded slides had been a challenge until recently13-18. We have developed the B7-H1 staining protocol for paraffin-embedded slides of pancreatic adenocarcinoma tissues. The B7-H1 staining protocol described here produces consistent membranous and cytoplasmic staining of B7-H1 with little background.

Immunohistochemical Staining of B7-H1 PD-L1 on Paraffin-embedded Slides of Pancreatic Adenocarcinoma Tissue

B7-H1 (PD-L1) and its binding to PD-1 provide a major tumor-induced immunosuppressive signal in the tumor&#x2019;s microenvironment. An immunohistochemical staining technique to characterize the expression and localization of B7-H1 in pancreatic adenocarcinoma is described here.

B7-H1/PD-L1, a member  of the B7 family of immune-regulatory cell-surface proteins, plays an important  role in the negative regulation of cell-mediated ...

Formation of Human Prostate Epithelium Using Tissue Recombination of Rodent Urogenital Sinus Mesenchyme and Human Stem Cells

Progress in prostate cancer research is severely limited by the availability of human-derived and hormone-na&iuml;ve model systems, which limit our ability to understand genetic and molecular events underlying prostate disease initiation. Toward developing better model systems for studying human prostate carcinogenesis, we and others have taken advantage of the unique pro-prostatic inductive potential of embryonic rodent prostate stroma, termed urogenital sinus mesenchyme (UGSM). When recombined with certain pluripotent cell populations such as embryonic stem cells, UGSM induces the formation of normal human prostate epithelia in a testosterone-dependent manner. Such a human model system can be used to investigate and experimentally test the ability of candidate prostate cancer susceptibility genes at an accelerated pace compared to typical rodent transgenic studies. Since Human embryonic stem cells (hESCs) can be genetically modified in culture using inducible gene expression or siRNA knock-down vectors prior to tissue recombination, such a model facilitates testing the functional consequences of genes, or combinations of genes, which are thought to promote or prevent carcinogenesis.
The technique of isolating pure populations of UGSM cells, however, is challenging and learning often requires someone with previous expertise to personally teach. Moreover, inoculation of cell mixtures under the renal capsule of an immunocompromised host can be technically challenging. Here we outline and illustrate proper isolation of UGSM from rodent embryos and renal capsule implantation of tissue mixtures to form human prostate epithelium. Such an approach, at its current stage, requires in vivo xenografting of embryonic stem cells; future applications could potentially include in vitro gland formation or the use of induced pluripotent stem cell populations (iPSCs).

To unravel the earliest molecular mechanisms underlying prostate cancer initiation, novel and innovative human model systems and approaches are desperately needed. The potential of pre-prostatic urogenital sinus mesenchyme (UGSM) to induce pluripotent stem cell populations to form human prostate epithelium is a powerful experimental tool in prostate research.

Progress in prostate cancer research is severely  limited by the availability of human-derived and hormone-na&iuml;ve model systems,  which limit our ...

Measuring Frailty in HIV-infected Individuals. Identification of Frail Patients is the First Step to Amelioration and Reversal of Frailty

A simple, validated protocol consisting of a battery of tests is available to identify elderly patients with frailty syndrome. This syndrome of decreased reserve and resistance to stressors increases in incidence with increasing age. In the elderly, frailty may pursue a step-wise loss of function from non-frail to pre-frail to frail. We studied frailty in HIV-infected patients and found that ~20% are frail using the Fried phenotype using stringent criteria developed for the elderly1,2. In HIV infection the syndrome occurs at a younger age.
HIV patients were checked for 1) unintentional weight loss; 2) slowness as determined by walking speed; 3) weakness as measured by a grip dynamometer; 4) exhaustion by responses to a depression scale; and 5) low physical activity was determined by assessing kilocalories expended in a week's time. Pre-frailty was present with any two of five criteria and frailty was present if any three of the five criteria were abnormal.
The tests take approximately 10-15 min to complete and they can be performed by medical assistants during routine clinic visits. Test results are scored by referring to standard tables. Understanding which of the five components contribute to frailty in an individual patient can allow the clinician to address relevant underlying problems, many of which are not evident in routine HIV clinic visits.

Frailty syndrome is commonly seen in the aged and reflects multi-system physiological change. However, with reduced functional reserve and resilience frailty is also known to be common in the HIV infected population. This study outlined an easily administered screening test to identify HIV patients with frailty. When significant components of frailty are identified, clinicians will be able to focus on amelioration of the problem and promote reversion to the pre-frail state.

A simple, validated protocol consisting of a battery of tests is available to identify elderly patients with frailty syndrome. This syndrome of decreased ...

A Thrombotic Stroke Model Based On Transient Cerebral Hypoxia-ischemia

Stroke research has endured many setbacks in translating neuroprotective therapies into clinical practice. In contrast, the real-world therapy (tPA thrombolysis) rarely produces benefits in mechanical occlusion-based experimental models, which dominate preclinical stroke research. This split between the bench and bedside suggests the need to employ tPA-responsive models in preclinical stroke research. To this end, a simple and tPA-reactive thrombotic stroke model is invented and described here. This model consists of transient occlusion of the unilateral common carotid artery and delivery of 7.5% oxygen through a face mask in adult mice for 30 min, while maintaining the animal rectal temperature at 37.5 &#177; 0.5 &#176;C. Although reversible ligation of the unilateral carotid artery or hypoxia each suppressed cerebral blood flow only transiently, the combination of both insults caused lasting reperfusion deficits, fibrin and platelet deposition, and large infarct in the middle cerebral artery-supplied territory. Importantly, tail-vein injection of recombinant tPA at 0.5, 1, or 4 hr post-tHI (10 mg/kg) provided time-dependent reduction of the mortality rate and infarct size. This new stroke model is simple and can be standardized across laboratories to compare experimental results. Further, it induces thrombosis without craniectomy or introducing pre-formed emboli. Given these unique merits, the tHI model is a useful addition to the repertoire of preclinical stroke research.

Thromboembolic stroke models are vital tools for optimizing the recanalization therapy. Here we report a murine thrombotic stroke model based on transient cerebral hypoxic-ischemic (tHI) insult, which triggers thrombosis and infarction, and responds favorably to tissue plasminogen activator (tPA)-mediated fibrinolysis in a therapeutic window similar to those in stroke patients.

Stroke research has endured many setbacks in translating neuroprotective therapies into clinical practice. In contrast, the real-world therapy (tPA ...

Phosphorus-31 Magnetic Resonance Spectroscopy: A Tool for Measuring In Vivo Mitochondrial Oxidative Phosphorylation Capacity in Human Skeletal Muscle

Skeletal muscle mitochondrial oxidative phosphorylation (OXPHOS) capacity, which is critically important in health and disease, can be measured in vivo and noninvasively in humans via phosphorus-31 magnetic resonance spectroscopy (31PMRS). However, the approach has not been widely adopted in translational and clinical research, with variations in methodology and limited guidance from the literature. Increased optimization, standardization, and dissemination of methods for in vivo 31PMRS would facilitate the development of targeted therapies to improve OXPHOS capacity and could ultimately favorably impact cardiovascular health. 31PMRS produces a noninvasive, in vivo measure of OXPHOS capacity in human skeletal muscle, as opposed to alternative measures obtained from explanted and potentially altered mitochondria via muscle biopsy. It relies upon only modest additional instrumentation beyond what is already in place on magnetic resonance scanners available for clinical and translational research at most institutions. In this work, we outline a method to measure in vivo skeletal muscle OXPHOS. The technique is demonstrated using a 1.5 Tesla whole-body MR scanner equipped with the suitable hardware and software for 31PMRS, and we explain a simple and robust protocol for in-magnet resistive exercise to rapidly fatigue the quadriceps muscle. Reproducibility and feasibility are demonstrated in volunteers as well as subjects over a wide range of functional capacities.

Phosphorus-31 Magnetic Resonance Spectroscopy: A Tool for Measuring In Vivo Mitochondrial Oxidative Phosphorylation Capacity in Human Skeletal Muscle

This work demonstrates the feasibility of an in vivo phosphorus-31 magnetic resonance spectroscopy (31PMRS) technique to quantify mitochondrial oxidative phosphorylation (OXPHOS) capacity in human skeletal muscle.

Skeletal muscle mitochondrial oxidative phosphorylation (OXPHOS) capacity, which is critically important in health and disease, can be measured in vivo ...

The 4-vessel Sampling Approach to Integrative Studies of Human Placental Physiology In Vivo

The human placenta is highly inaccessible for research while still in utero. The current understanding of human placental physiology in vivo is therefore largely based on animal studies, despite the high diversity among species in placental anatomy, hemodynamics and duration of the pregnancy. The vast majority of human placenta studies are ex vivo perfusion studies or in vitro trophoblast studies. Although in vitro studies and animal models are essential, extrapolation of the results from such studies to the human placenta in vivo is uncertain. We aimed to study human placenta physiology in vivo at term, and present a detailed protocol of the method. Exploiting the intraabdominal access to the uterine vein just before the uterine incision during planned cesarean section, we collect blood samples from the incoming and outgoing vessels on the maternal and fetal sides of the placenta. When combining concentration measurements from blood samples with volume blood flow measurements, we are able to quantify placental and fetal uptake and release of any compound. Furthermore, placental tissue samples from the same mother-fetus pairs can provide measurements of transporter density and activity and other aspects of placental functions in vivo. Through this integrative use of the 4-vessel sampling method we are able to test some of the current concepts of placental nutrient transfer and metabolism in vivo, both in normal and pathological pregnancies. Furthermore, this method enables the identification of substances secreted by the placenta to the maternal circulation, which could be an important contribution to the search for biomarkers of placenta dysfunction.

The 4-vessel Sampling Approach to Integrative Studies of Human Placental Physiology In Vivo

We present a detailed method to study human placental physiology in vivo at term. The method combines blood sampling from the incoming and outgoing vessels on the maternal and fetal sides of the placenta with ultrasound measurements of volume blood flow and placental tissue sampling.

The human placenta is highly inaccessible for research while still in utero. The current understanding of human placental physiology in vivo is therefore ...

Measuring the Effect of Chemicals on the Growth and Reproduction of Caenorhabditis elegans

Toxicological evaluation is crucial for understanding the effects of chemicals on living organisms in basic and applied biological science fields. A non-mammalian soil round worm, Caenorhabditis elegans, is a valuable model organism for toxicology studies due to its convenience and lack of animal ethics issues compared with mammalian animal systems. In this protocol, a detailed procedure of toxicological evaluation of chemicals in C. elegans is described. A clinical anticancer drug, etoposide, which targets human topoisomerase II and inhibits DNA replication of human cancer cells, was selected as a model testing chemical. Age-synchronized C. elegans eggs were exposed to either dimethyl sulfoxide (DMSO) or etoposide, and then the growth of C. elegans was monitored every day for 4 days by the stereo microscope observation. The total number of eggs laid from C. elegans treated with DMSO or etoposide was also counted by using the stereo microscope. Etoposide treatment significantly affected the growth and reproduction of C. elegans. By comparison of the total number of eggs laid from worms with different treatment periods of chemicals, it can be decided that the reproductive toxicity of chemicals on C. elegans reproduction is reversible or irreversible. These protocols may be helpful for both the development of various drugs and risk assessment of environmental toxicants.

Measuring the Effect of Chemicals on the Growth and Reproduction of Caenorhabditis elegans

A basic protocol to evaluate the toxicity of chemicals in a model animal, Caenorhabditis elegans, is described. The method is convenient and useful for the development of pharmaceuticals as well as for the risk assessment of various environmental pollutants.

Toxicological evaluation is crucial for understanding the effects of chemicals on living organisms in basic and applied biological science fields. A ...

A Primary Human Trophoblast Model to Study the Effect of Inflammation Associated with Maternal Obesity on Regulation of Autophagy in the Placenta

Maternal obesity is associated with an increased risk of adverse perinatal outcomes that are likely mediated by compromised placental function that can be attributed to, in part, the dysregulation of autophagy. Aberrant changes in the expression of autophagy regulators in the placentas from obese pregnancies may be regulated by inflammatory processes associated with both obesity and pregnancy. Described here is a protocol for sampling of villous tissue and isolation of villous cytotrophoblasts from the term human placenta for primary cell culture. This is followed by a method for simulating the inflammatory milieu in the obese intrauterine environment by treating primary trophoblasts from lean pregnancies with tumor necrosis factor alpha (TNF&#945;), a proinflammatory cytokine that is elevated in obesity and in pregnancy. Through the implementation of the protocol described here, it is found that exposure to exogenous TNF&#945; regulates the expression of Rubicon, a negative regulator of autophagy, in trophoblasts from lean pregnancies with female fetuses. While a variety of biological factors in the obese intrauterine environment maintain the potential to modulate critical pathways in trophoblasts, this ex vivo system is especially useful for determining if expression patterns observed in vivo in human placentas with maternal obesity are a direct result of TNF&#945; signaling. Ultimately, this approach affords the opportunity to parse out the regulatory and molecular implications of inflammation associated with maternal obesity on autophagy and other critical cellular pathways in trophoblasts that have the potential to impact placental function.

Presented here is a protocol for sampling of human placental villous tissue followed by isolation of cytotrophoblasts for primary cell culture. Treatment of trophoblasts with TNF&#945; recapitulates inflammation in the obese intrauterine environment and facilitates the discovery of molecular targets regulated by inflammation in placentas with maternal obesity.

Maternal obesity is associated with an increased risk of adverse perinatal outcomes that are likely mediated by compromised placental function that can be ...

Effect of Artificial Tear Formulations on the Metabolic Activity of Human Corneal Epithelial Cells after Exposure to Desiccation

Artificial lipid-containing tear formulations are developed to reduce tear evaporation by the restoration of a deficient tear lipid layer. Artificial tear formulations that prevent cell desiccation will result in ocular surface protection and the maintenance of cell metabolic activity. During dehydration, cells undergo the process of loss of metabolic activity and subsequently cell death. This work describes a method for assessing the efficacy of artificial tear formulations. The metabolic dye (i.e., alamarBlue) changes from a low fluorescent molecule resazurin to a fluorescent molecule resorufin in viable cells. The biological performance of an artificial tear formulation is measured as the ability of the formulation to (a) maintain cell viability and (b) provide cell protection from desiccation. Growth media and saline are used as controls for the cell viability/desiccation tests. Cells are incubated with test solutions for 30 min and then desiccated for 0 or 5 min at 37 &#176;C and 45% relative humidity. Cell metabolic activity after initial exposure and after cell desiccation is then determined. The results show the comparative effects of eye drop formulations on cell metabolic activity and desiccation protection. This method can be used to test dry eye formulations that are designed to treat individuals with evaporative dry eye.

The purpose of this protocol is to evaluate if different artificial tear formulations can protect human corneal epithelial cells from desiccation using an in vitro model. After exposure to artificial tear formulations and desiccation, human corneal epithelial cells are assessed for metabolic activity.

Artificial lipid-containing tear formulations are developed to reduce tear evaporation by the restoration of a deficient tear lipid layer. Artificial tear ...