This work is supported by funding from the United States Army, Medical Research and Materiel Command, Combat Casualty Care Program.&#160;We thank LTC Kevin S. Akers, MD and Ms. Kristen R. Lye for their assistance in making the video.

Prior to any human procedure, the institutional&#160;review board (IRB) must approve the protocol. The protocol used in this study was approved by the US Army Medical Research and Materiel Command IRB. The protocol is designed to demonstrate the physiological responses of compensation to a progressive reduction in central blood volume similar to that experienced by individuals during ongoing hemorrhage in a controlled and reproducible laboratory setting. The laboratory room temperature is controlled at 23 - 25 &#730;C.
1. Equipment Preparation
<ol>
	<li>Turn on equipment and devices requiring warm-up and calibration. 
	NOTE: Equipment and devices include a data acquisition system to record data at 1 Hz; two separate devices that provide noninvasive, continuous measurements of brachial artery blood pressure and arterial oxygen saturation (SpO2) using two separate infrared finger photoplethysmography cuff sensors9-11; a capnograph for measurement of end-tidal CO2 and respiratory rate; and a finger pulse oximeter to acquire peripheral pulsatile arterial waveforms for measuring Compensatory Reserve.</li>
	<li>Synchronize all of the instruments with internal clocks by adjusting the time stamp on each instrument to match a laboratory master clock that will be used to mark time during the experiment.</li>
</ol>
2. Subject Preparation
<ol>
	<li>Instruct the subject to avoid caffeine, alcohol, and strenuous exercise 24 h prior to testing, and to avoid eating at least 2 h prior to the protocol in the event that hemodynamic decompensation induces nausea.</li>
	<li>Prior to initiation of the protocol, have the physician perform a medical screening exam to ensure the subject meets minimal health requirements, and ensures the absence of exclusion criteria (nicotine use, hypertension, autonomic dysfunction, or history of syncopal episodes). Since pregnancy is an exclusion criterion for participation, require female participants to take a standard urine pregnancy test on the day of the study. 
	NOTE: For the safety of the subject, the study physician is certified in advanced life support, and is present during the study. A fully-equipped &#39;crash cart&#39; is immediately available to support the subject&#39;s airway, respiration, and circulation in the event of loss of consciousness or an acute cardiac arrhythmia taking place during the LBNP procedure.</li>
	<li>Inform the subject about the procedure, and obtain written consent to participate in the study. 
	NOTE: Explain to the subject that the goal of the study is to apply LBNP until the onset of cardiovascular decompensation (presyncope). Explain that there are cardiovascular parameters that define this point, and LBNP will be terminated when these cardiovascular parameters are observed. Inform the subject that they may also experience symptoms typically associated with presyncope during the LBNP procedure. Instruct the subject to notify the investigator if these symptoms occur and LBNP will immediately be terminated.</li>
	<li>Place the neoprene LBNP skirt on the subject. Ensure that the skirt is snug around the waist and torso in order to create an air-tight seal.</li>
	<li>Instruct the subject to lay supine on the bed of the LBNP chamber while straddling a stationary post to secure the torso in place during LBNP. Instruct the subject to relax the lower body during LBNP exposure. Secure the subject into the LBNP chamber by sliding the bed into the chamber and attaching the neoprene skirt to the chamber opening to create an air-tight seal. 
	NOTE: The LBNP chamber provides the capability of accurately (within 0.1 mmHg) controlling the internal pressure from 0 to -100 mmHg either manually or with a computerized profile. The chamber includes an adjustable saddle to secure the subject&#39;s body position. Clear plexiglass windows allow for visualization of the subject&#39;s legs. An adjustable aluminum waist board allows for an air-tight seal to be created by a neoprene skirt worn by the subject and the LBNP chamber at the level of the iliac crest (Figure 1).</li>
	<li>Place electrocardiogram (ECG) electrodes on the right and left humoral-clavicular joints, and on the right and left lower ribs (total of 4) in a modified lead II configuration (Figure 1) for continuous measurement of heart rate.</li>
	<li>Position the subject&#39;s arms on the arm rests, adjusted so that the hands are supported at heart level. Using appropriate size finger cuffs, place an infrared finger photoplethysmography&#160;device on the left and right middle fingers for continuous noninvasive beat-to-beat measurement of blood pressure.</li>
	<li>Attach the finger cuffs to the pressure monitors. Calibrate the devices and record blood pressure according to the manufacturer instructions.12 Enter subject information (age, sex, height, and weight) to enable the appropriate assumptions for calculation (estimation) of stroke volume, cardiac output and peripheral vascular resistance by the Modelflow algorithm if desired.13,14</li>
	<li>Place the finger pulse oximeter on the right index finger for continuous measurement of compensatory reserve1,12 (Figure 2).</li>
	<li>Place a nasal cannula on the subject and instruct the subject to breathe through the nose to assure sensitive reflections in inspiration and expiration. Nasal air sampling will allow the subject to talk freely for self-reporting of developing symptoms. Connect the nasal cannula to the capnograph for the continuous measurement of respiration and end tidal CO2.</li>
</ol>
3. Performing the LBNP Protocol
<ol>
	<li>Start data recording by clicking the &#34;Start&#34; button on the data acquisition system. Record baseline data for 5 min. Initiate the first level of central hypovolemia by turning on the vacuum motor and setting negative pressure to -15 mmHg, and hold this pressure for 5 min. Figure 3 outlines the protocol.</li>
	<li>Increase the LBNP to -30 mmHg, and hold this pressure for 5 min.</li>
	<li>Increase the LBNP to -45 mmHg, and hold this pressure for 5 min.</li>
	<li>Increase the LBNP to -60 mmHg, and hold this pressure for 5 min.</li>
	<li>Increase the LBNP to -70 mmHg, and hold this pressure for 5 min.</li>
	<li>Continue to increase LBNP levels by -10 mmHg every 5 min until the end of the protocol (5 min at -100 mmHg LBNP) or the point of hemodynamic decompensation. Terminate the LBNP by pressing the pressure release button on the LBNP chamber. 
	NOTE: Hemodynamic decompensation is identified by a precipitous fall in systolic arterial pressure below 80 mmHg, or the subject reporting presyncopal symptoms such as grey-out (loss of color vision), tunnel vision, sweating, nausea or dizziness (Figure 4).</li>
	<li>Continue recording data on the data acquisition system during 10 min after the cessation of LBNP (postLBNP recovery).</li>
	<li>Stop recording data at the end of the 10-min recovery period by clicking the &#34;Stop&#34; button on the data acquisition system.</li>
	<li>Detach all instrumentation from the subject and remove the subject from the LBNP chamber. Ask the subject to sit after stepping down from the LBNP platform to ensure they are symptom-free before leaving the laboratory. The study is now complete.</li>
	<li>Download data files from the acquisition system for extraction of the Compensatory Reserve Index (CRI), Mean Arterial Pressure (MAP), heart rate, and SpO2 values. 1,15,16</li>
</ol>

<ol>
	<li>Convertino, V. A., Wirt, M. D., Glenn, J. P., Lein, B. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+compensatory+reserve+for+early+and+accurate+prediction+of+hemodynamic+compromise:+a+review+of+the+underlying+physiology.">The compensatory reserve for early and accurate prediction of hemodynamic compromise: a review of the underlying physiology.</a> Shock. 45 (6), 580-590 (2016).</li><li>Eastridge, B. 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=Death+on+the+battlefield+(2001-2011):+Implications+for+the+future+of+combat+casualty+care.">Death on the battlefield (2001-2011): Implications for the future of combat casualty care.</a> Journal of Trauma and Acute Care Surgery. 73 (6), S431-S437 (2012).</li><li>Orlinsky, M., Shoemaker, W., Reis, E. D., Kerstein, M. 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Surg. 192 (6), 727-731 (2006).</li><li>Brunauer, A., 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=The+arterial+blood+pressure+associated+with+terminal+cardiovascular+collapse+in+critically+ill+patients:+a+retrospective+cohort+study.">The arterial blood pressure associated with terminal cardiovascular collapse in critically ill patients: a retrospective cohort study.</a> Crit Care. 18 (6), 719 (2014).</li><li>Hinojosa-Laborde, C., 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=Validation+of+lower+body+negative+pressure+as+an+experiomental+model+of+hemorrhage.">Validation of lower body negative pressure as an experiomental model of hemorrhage.</a> J. Appl. Physiol. 116, 406-415 (2014).</li><li>Martina, J. 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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=Continuous+stroke+volume+monitoring+by+modelling+flow+from+non-invasive+measurement+of+arterial+pressure+in+humans+under+orthostatic+stress.">Continuous stroke volume monitoring by modelling flow from non-invasive measurement of arterial pressure in humans under orthostatic stress.</a> Clin. Sci. 97, 291-301 (1999).</li><li>Leonetti, 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=Stroke+volume+monitored+by+modeling+flow+from+finger+arterial+pressure+waves+mirrors+blood+volume+withdrawn+by+phlebotomy.">Stroke volume monitored by modeling flow from finger arterial pressure waves mirrors blood volume withdrawn by phlebotomy.</a> Clin. Auton. Res. 14 (3), 176-181 (2004).</li><li>Convertino, V. A., Grudic, G., Mulligan, J., Moulton, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Estimation+of+individual-specific+progression+to+impending+cardiovascular+instability+using+arterial+waveforms.">Estimation of individual-specific progression to impending cardiovascular instability using arterial waveforms.</a> J. Appl. Physiol(Bethesda, Md :1985). 115 (8), 1196-1202 (2013).</li><li>Convertino, V. A., 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=Individual-specific,+beat-to-beat+trending+of+significant+human+blood+loss:+the+compensatory+reserve.">Individual-specific, beat-to-beat trending of significant human blood loss: the compensatory reserve.</a> Shock. 44 (Supplement 1), 27-32 (2015).</li><li>Cooke, W. H., Ryan, K. L., Convertino, V. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lower+body+negative+pressure+as+a+model+to+study+progression+to+acute+hemorrhagic+shock+in+humans.">Lower body negative pressure as a model to study progression to acute hemorrhagic shock in humans.</a> J. Appl. Physiol. 96, 1249-1261 (2004).</li><li>Convertino, V. A., 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=Inspiratory+resistance+maintains+arterial+pressure+during+central+hypovolemia:+implications+for+treatment+of+patients+with+severe+hemorrhage.">Inspiratory resistance maintains arterial pressure during central hypovolemia: implications for treatment of patients with severe hemorrhage.</a> Crit Care Med. 35 (4), 1145-1152 (2007).</li><li>Carter, R., Hinojosa-Laborde, C., Convertino, V. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Variability+in+integration+of+mechanisms+associated+with+high+tolerance+to+progressive+reductions+in+central+blood+volume:+the+compensatory+reserve.">Variability in integration of mechanisms associated with high tolerance to progressive reductions in central blood volume: the compensatory reserve.</a> Physiol Reports. 4 (1), (2016).</li><li>Convertino, V. A., Sather, 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=Vasoactive+neuroendocrine+responses+associated+with+tolerance+to+lower+body+negative+pressure+in+humans.">Vasoactive neuroendocrine responses associated with tolerance to lower body negative pressure in humans.</a> Clin. Physiol. 20, 177-184 (2000).</li><li>Convertino, V. A., 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=Use+of+advanced+machine-learning+techniques+for+noninvasive+monitoring+of+hemorrhage.">Use of advanced machine-learning techniques for noninvasive monitoring of hemorrhage.</a> J. Trauma. 71 (1 Suppl), S25-S32 (2011).</li><li>Convertino, V. A., Rickards, C. A., Ryan, K. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Autonomic+mechanisms+associated+with+heart+rate+and+vasoconstrictor+reserves.">Autonomic mechanisms associated with heart rate and vasoconstrictor reserves.</a> Clin. Auton. Res. 22, 123-130 (2012).</li><li>Rickards, C. A., Ryan, K. L., Cooke, W. H., Convertino, V. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tolerance+to+central+hypovolemia:+the+influence+of+oscillations+in+arterial+pressure+and+cerebral+blood+velocity.">Tolerance to central hypovolemia: the influence of oscillations in arterial pressure and cerebral blood velocity.</a> J. Appl. Physiol. 111 (4), 1048-1058 (2011).</li><li>Johnson, B. D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reductions+in+central+venous+pressure+by+lower+body+negative+pressure+of+blood+loss+elicit+similar+hemodynamic+responses.">Reductions in central venous pressure by lower body negative pressure of blood loss elicit similar hemodynamic responses.</a> J. Appl. 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Trauma. 66, S69-S76 (2009).</li><li>Kragh, 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=Survival+with+emergency+tourniquet+use+to+stop+bleeding+in+major+limb+trauma.">Survival with emergency tourniquet use to stop bleeding in major limb trauma.</a> Ann Surgery. 249 (1), 1-7 (2009).</li><li>Chung, K. 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=Continous+renal+replacement+therapy+improves+survival+in+severly+burned+military+casualties+with+acute+kidney+injury.">Continous renal replacement therapy improves survival in severly burned military casualties with acute kidney injury.</a> J. Trauma. 64, S179-S187 (2008).</li><li>Stewart, C. 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The authors declare that they have no competing financial interests. The views expressed herein are the private views of the authors and are not to be construed as representing those of the US Department of the Army or the US Department of Defense.

Using LBNP to cause progressive and continuous reductions in central blood volume, we were able to induce a typical response of hemodynamic decompensation in the subject, characterized by a sudden onset of hypotension and bradycardia (Figure 7). It is important to understand that the integrated compensatory response to hemorrhage is very complex,19 resulting in significant individual variability in the tolerance to blood loss.1 As such, some individuals have relatively responsive co...

The most important function of the cardiovascular system is the control of adequate perfusion (blood flow and oxygen delivery) to all tissues of the body through homeostatic regulation of arterial blood pressure. Various mechanisms of compensation (e.g., autonomic nervous system activity, cardiac rate and contractility, venous return, vasoconstriction, respiration) contribute to maintain normal physiological levels of oxygen in the tissues.1 Reductions in circulating blood volume such as those caused by hemorrhage can compromise the ability of cardiovascular compensatory mechanisms and ultimately lead to low arterial blood pressure, serious tissue hypoxia, and circulatory shock that can be fatal.
Circulatory shock caused by severe bleeding (i.e., hemorrhagic shock) is a leading cause of death due to trauma.2 One of the most challenging aspects of preventing a patient from developing shock is our inability to recognize its early onset. Early and accurate assessment of the progression toward the development of shock is currently limited in the clinical setting by technologies (i.e., medical monitors) that provide measurements of vital signs that change very little in the early stages of blood loss because of the body&#39;s numerous compensatory mechanisms for regulating blood pressure.3-6 As such, the capability to measure the sum total of the body&#39;s reserve to compensate for blood loss represents the most accurate reflection of tissue perfusion state and the risk of developing shock.1 This reserve is called the compensatory reserve which can be accurately assessed by real-time measurements of changes in features of the arterial waveform.1 Depletion of the compensatory reserve replicates the terminal cardiovascular instability observed in critically ill patients with sudden onset of hypotension; a condition known as hemodynamic decompensation.7
The relationship between the utilization of the compensatory reserve and regulation of blood pressure during ongoing blood loss in humans can be demonstrated in the laboratory using a comprehensive set of physiological measurements (e.g., blood pressures, heart rate, arterial blood oxygen saturation, stroke volume, cardiac output, vascular resistance, respiration rate, pulse character, mental status, end-tidal CO2, tissue oxygen) provided by standard physiological monitoring during continuous progressive reductions in central blood volume similar to those that occur during hemorrhage. Lowered central blood volume can be induced noninvasively with progressive increases in Lower Body Negative Pressure (LBNP).8 Using this combination of physiological measurements and LBNP, the conceptual understanding of how to assess the body&#39;s ability to compensate for reduced central blood volume can easily be demonstrated. This study depicts the prelab preparation, the demonstration of compensatory response in relation to other physiological responses during simulated hemorrhage, and the postlab evaluation of results. The experimental techniques necessary for making measurements of compensatory reserve are demonstrated in a human volunteer.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Dynamic Research Evaluation Workstation (DREW) data acquisition syetem</td>
			<td>NA</td>
			<td>NA</td>
			<td>Custom Built by ISR personnel.&#160; The DREW allows for time synchronization of both digital and analog signal data collection from up to 16 independent instruments with a sampling rate of 1000 Hz.</td>
		</tr>
		<tr>
			<td>Finometer</td>
			<td>Finapress Medical Systems (FMS)</td>
			<td>Model 1</td>
			<td>Device that provides non-invasive, continuous measurements of brachial artery blood pressure and arterial oxygen saturation (SpO2) using two separate infrared finger photophlethymography cuff sensors.</td>
		</tr>
		<tr>
			<td>BCI Capnocheck Plus</td>
			<td>Smith Medical PM Inc.</td>
			<td>9004</td>
			<td>Capnograph used to measure&#160; end tidal CO2 and respiration rate</td>
		</tr>
		<tr>
			<td>CipherOX&#160;</td>
			<td>Flashback Technologies Inc.</td>
			<td>R200</td>
			<td>Investigational device used to calculate Compensatory Reserve Index (CRI)</td>
		</tr>
		<tr>
			<td>Nonin 9560 Pulse Oximeter</td>
			<td>Nonin</td>
			<td>9560</td>
			<td>finger pulse oximeter</td>
		</tr>
		<tr>
			<td>Lower Body Negative Pressure Chamber (LBNP)</td>
			<td>NASA</td>
			<td>79K32632-1</td>
			<td>Custom Chamber built by NASA</td>
		</tr>
		<tr>
			<td>ECG Biotach</td>
			<td>Gould</td>
			<td>13-6615-65</td>
			<td>Electrocardiograph for measuring ECG</td>
		</tr>
		<tr>
			<td>Nasal CO2 Sample Line</td>
			<td>Salter Labs</td>
			<td>REF 4000</td>
			<td>Latex free nasal cannula for sampling expired air</td>
		</tr>
	</tbody>
</table>

integrated compensatory responses in a human model of hemorrhage

Hemorrhage is the leading cause of trauma-related deaths, partly because early diagnosis of the severity of blood loss is difficult. Assessment of hemorrhaging patients is difficult because current clinical tools provide measures of vital signs that remain stable during the early stages of bleeding due to compensatory mechanisms. Consequently, there is a need to understand and measure the total integration of mechanisms that compensate for reduced circulating blood volume and how they change during ongoing progressive hemorrhage. The body&#39;s reserve to compensate for reduced circulating blood volume is called the &#39;compensatory reserve&#39;. The compensatory reserve can be accurately evaluated with real-time measurements of changes in the features of the arterial waveform measured with the use of a high-powered computer. Lower Body Negative Pressure (LBNP) has been shown to simulate many of the physiological responses in humans associated with hemorrhage, and is used to study the compensatory response to hemorrhage. The purpose of this study is to demonstrate how compensatory reserve is assessed during progressive reductions in central blood volume with LBNP as a simulation of hemorrhage.

The LBNP procedure causes a reduction in air pressure around the lower torso and legs. As this vacuum is progressively increased, blood volume shifts from the head and upper torso to the lower body to create a state of central hypovolemia. The progressive reduction in central blood volume (i.e., LBNP) produces significant alterations in the features of the arterial waveform measured with the infrared finger photoplethysmograph (Figure 5). The Compensatory Reserve...

Watch this Scientific Journal Video about Integrated Compensatory Responses in a Human Model of Hemorrhage at JoVE.com

Integrated Compensatory Responses in a Human Model of Hemorrhage

The purpose of this protocol is to demonstrate the techniques for measuring compensatory responses to reduced central blood volume using lower body negative pressure as a noninvasive experimental model of human hemorrhage which can be used to quantify the total integration of compensatory mechanisms to blood volume deficit in humans.

Hemorrhage is the leading cause of trauma-related deaths, partly because early diagnosis of the severity of blood loss is difficult. Assessment of ...

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12.4K Views.  JBSA Fort Sam Houston. The purpose of this protocol is to demonstrate the techniques for measuring compensatory responses to reduced central blood volume using lower body negative pressure as a noninvasive experimental model of human hemorrhage which can be used to quantify the total integration of compensatory mechanisms to blood volume deficit in humans.

Video: Integrated Compensatory Responses in a Human Model of Hemorrhage

Stem Cell Transplantation in an in vitro Simulated Ischemia/Reperfusion Model

Stem cell transplantation protocols are finding their way into clinical practice1,2,3. Getting better results, making the protocols more robust, and finding new sources for implantable cells are the focus of recent research4,5. Investigating the effectiveness of cell therapies is not an easy task and new tools are needed to investigate the mechanisms involved in the treatment process6. We designed an experimental protocol of ischemia/reperfusion in order to allow the observation of cellular connections and even subcellular mechanisms during ischemia/reperfusion injury and after stem cell transplantation and to evaluate the efficacy of cell therapy. H9c2 cardiomyoblast cells were placed onto cell culture plates7,8. Ischemia was simulated with 150 minutes in a glucose free medium with oxygen level below 0.5%. Then, normal media and oxygen levels were reintroduced to simulate reperfusion. After oxygen glucose deprivation, the damaged cells were treated with transplantation of labeled human bone marrow derived mesenchymal stem cells by adding them to the culture. Mesenchymal stem cells are preferred in clinical trials because they are easily accessible with minimal invasive surgery, easily expandable and autologous. After 24 hours of co-cultivation, cells were stained with calcein and ethidium-homodimer to differentiate between live and dead cells. This setup allowed us to investigate the intercellular connections using confocal fluorescent microscopy and to quantify the survival rate of postischemic cells by flow cytometry. Confocal microscopy showed the interactions of the two cell populations such as cell fusion and formation of intercellular nanotubes. Flow cytometry analysis revealed 3 clusters of damaged cells which can be plotted on a graph and analyzed statistically. These populations can be investigated separately and conclusions can be drawn on these data on the effectiveness of the simulated therapeutical approach.

Stem Cell Transplantation in an in vitro Simulated Ischemia/Reperfusion Model

We demonstrate how to set up an in vitro ischemia/reperfusion model and how to evaluate the effect of stem cell therapy on postischemic cardiac cells.

Stem cell transplantation protocols are finding their way into clinical practice1,2,3. Getting better results, making the protocols more robust, and ...

A Low Mortality Rat Model to Assess Delayed Cerebral Vasospasm After Experimental Subarachnoid Hemorrhage

Objective: To characterize and establish a reproducible model that demonstrates delayed cerebral vasospasm after aneurysmal subarachnoid hemorrhage (SAH) in rats, in order to identify the initiating events, pathophysiological changes and potential targets for treatment.
Methods: Twenty-eight male Sprague-Dawley rats (250 - 300 g) were arbitrarily assigned to one of two groups - SAH or saline control. Rat subarachnoid hemorrhage in the SAH group (n=15) was induced by double injection of autologous blood, 48 hr apart, into the cisterna magna. Similarly, normal saline (n=13) was injected into the cisterna magna of the saline control group. Rats were sacrificed on day five after the second blood injection and the brains were preserved for histological analysis. The degree of vasospasm was measured using sections of the basilar artery, by measuring the internal luminal cross sectional area using NIH Image-J software. The significance was tested using Tukey/Kramer's statistical analysis.
Results: After analysis of histological sections, basilar artery luminal cross sectional area were smaller in the SAH than in the saline group, consistent with cerebral vasospasm in the former group. In the SAH group, basilar artery internal area (.056 &mu;m &plusmn; 3) were significantly smaller from vasospasm five days after the second blood injection (seven days after the initial blood injection), compared to the saline control group with internal area (.069 &plusmn; 3; p=0.004). There were no mortalities from cerebral vasospasm.
Conclusion: The rat double SAH model induces a mild, survivable, basilar artery vasospasm that can be used to study the pathophysiological mechanisms of cerebral vasospasm in a small animal model. A low and acceptable mortality rate is a significant criterion to be satisfied for an ideal SAH animal model so that the mechanisms of vasospasm can be elucidated 7, 8. Further modifications of the model can be made to adjust for increased severity of vasospasm and neurological exams.

Aneurysmal subarachnoid hemorrhage (SAH) is bleeding that occurs into the subarachnoid space when an aneurysm ruptures. While the morbidity and mortality from this event has been on a decline due to improved treatment approaches, the risk of vasospasm after subarachnoid hemorrhage continues to be the same as it was several years ago. The importance of establishing a comprehensive and reproducible animal model to identify initiating events of cerebral vasospasm has been the focus of research since the first use of rats in an experimental vasospasm model in 1979 by Barry et al. Early work in rats demonstrated that a single injection of autologous blood into the cisterna magna led to acute (within minutes) but not delayed cerebral vasospasm 3, 6, 14. Here we characterize a low mortality SAH rat model that results in reproducible delayed vasospasm.

Objective: To characterize and establish a reproducible model that demonstrates delayed cerebral vasospasm after aneurysmal subarachnoid hemorrhage (SAH) ...

A Murine Model of Subarachnoid Hemorrhage

In this video publication a standardized mouse model of subarachnoid hemorrhage (SAH) is presented. Bleeding is induced by endovascular Circle of Willis perforation (CWp) and proven by intracranial pressure (ICP) monitoring. Thereby a homogenous blood distribution in subarachnoid spaces surrounding the arterial circulation and cerebellar fissures is achieved. Animal physiology is maintained by intubation, mechanical ventilation, and continuous on-line monitoring of various physiological and cardiovascular parameters: body temperature, systemic blood pressure, heart rate, and hemoglobin saturation. Thereby the cerebral perfusion pressure can be tightly monitored resulting in a less variable volume of extravasated blood. This allows a better standardization of endovascular filament perforation in mice and makes the whole model highly reproducible. Thus it is readily available for pharmacological and pathophysiological studies in wild type and genetically altered mice.

A standardized mouse model of subarachnoid hemorrhage by intraluminal Circle of Willis perforation is described. Vessel perforation and subarachnoid bleeding are monitored by intracranial pressure monitoring. In addition various vital parameters are recorded and controlled to maintain physiologic conditions.

In this video publication a standardized mouse model of subarachnoid  hemorrhage (SAH) is presented. Bleeding is induced by endovascular Circle of  Willis ...

Excitotoxic Stimulation of Brain Microslices as an In vitro Model of Stroke

Examining molecular mechanisms involved in neuropathological conditions, such as ischemic stroke, can be difficult when using whole animal systems. As such, primary or &#39;neuronal-like&#39; cell culture systems are commonly utilized. While&#160;these systems are relatively easy to work with, and are useful model systems in which various functional outcomes (such as cell death) can be readily quantified, the examined outcomes and pathways in cultured immature neurons (such as excitotoxicity-mediated cell death pathways) are not necessarily the same as those observed in mature brain, or in intact tissue. Therefore, there is the need to develop models in which cellular mechanisms in mature neural tissue can be examined. We have developed an in vitro technique that can be used to investigate a variety of molecular pathways in intact nervous tissue. The technique described herein utilizes rat cortical tissue, but this technique can be adapted to use tissue from a variety of species (such as mouse, rabbit, guinea pig, and chicken) or brain regions (for example, hippocampus, striatum, etc.). Additionally, a variety of stimulations/treatments can be used (for example, excitotoxic, administration of inhibitors, etc.). In conclusion, the brain slice model described herein can be used to examine a variety of molecular mechanisms involved in excitotoxicity-mediated brain injury.

Excitotoxic Stimulation of Brain Microslices as an In vitro Model of Stroke

We have developed a brain slice model which can be used to examine molecular mechanisms involved in excitotoxicity-mediated brain injury.&#160;This technique generates viable mature brain tissue and reduces animal numbers required for experimentation, whilst keeping the neuronal circuitry, cellular interactions, and postsynaptic compartments partly intact.

Examining molecular mechanisms involved in neuropathological conditions, such as ischemic stroke, can be difficult when using whole animal systems. As ...

Urinary Bladder Distention Evoked Visceromotor Responses as a Model for Bladder Pain in Mice

Approximately 3-8 million people in the United States suffer from interstitial cystitis/bladder pain syndrome (IC/BPS), a debilitating condition characterized by increased urgency and frequency of urination, as well as nocturia and general pelvic pain, especially upon bladder filling or voiding. Despite years of research, the cause of IC/BPS remains elusive and treatment strategies are unable to provide complete relief to patients. In order to study nervous system contributions to the condition, many animal models have been developed to mimic the pain and symptoms associated with IC/BPS. One such murine model is urinary bladder distension (UBD). In this model, compressed air of a specific pressure is delivered to the bladder of a lightly anesthetized animal over a set period of time. Throughout the procedure, wires in the superior oblique abdominal muscles record electrical activity from the muscle. This activity is known as the visceromotor response (VMR) and is a reliable and reproducible measure of nociception. Here, we describe the steps necessary to perform this technique in mice including surgical manipulations, physiological recording, and data analysis. With the use of this model, the coordination between primary sensory neurons, spinal cord secondary afferents, and higher central nervous system areas involved in bladder pain can be unraveled. This basic science knowledge can then be clinically translated to treat patients suffering from IC/BPS.

Approximately 3-8 million people in the United States suffer from interstitial cystitis/bladder pain syndrome (IC/BPS), a debilitating condition characterized in part by pelvic pain. In order to study nervous system contributions to the condition, a physiological model of urinary bladder pain is used in mice and rats.

Approximately 3-8 million people in the United States suffer from interstitial cystitis/bladder pain syndrome (IC/BPS), a debilitating condition ...

The Rabbit Blood-shunt Model for the Study of Acute and Late Sequelae of Subarachnoid Hemorrhage: Technical Aspects

Early brain injury and delayed cerebral vasospasm both contribute to unfavorable outcomes after subarachnoid hemorrhage (SAH). Reproducible and controllable animal models that simulate both conditions are presently uncommon. Therefore, new models are needed in order to mimic human pathophysiological conditions resulting from SAH.
This report describes the technical nuances of a rabbit blood-shunt SAH model that enables control of intracerebral pressure (ICP). An extracorporeal shunt is placed between the arterial system and the subarachnoid space, which enables examiner-independent SAH in a closed cranium. Step-by-step procedural instructions and necessary equipment are described, as well as technical considerations to produce the model with minimal mortality and morbidity. Important details required for successful surgical creation of this robust, simple and consistent ICP-controlled SAH rabbit model are described.

The experimental intracranial pressure-controlled blood shunt subarachnoid hemorrhage (SAH) model in the rabbit combines the standard procedures &#8212; subclavian artery cannulation and transcutaneous cisterna magna puncture, which enables close mimicking of human pathophysiological conditions after SAH. We present step-by-step instructions and discuss key surgical points for successful experimental SAH creation.

Early brain injury and delayed cerebral vasospasm both contribute to unfavorable outcomes after subarachnoid hemorrhage (SAH). Reproducible and ...

Mouse Pneumonectomy Model of Compensatory Lung Growth

In humans, disrupted repair and remodeling of injured lung contributes to a host of acute and chronic lung disorders which may ultimately lead to disability or death. Injury-based animal models of lung repair and regeneration are limited by injury-specific responses making it difficult to differentiate changes related to the injury response and injury resolution from changes related to lung repair and lung regeneration. However, use of animal models to identify these repair and regeneration signaling pathways is critical to the development of new therapies aimed at improving pulmonary function following lung injury. The mouse pneumonectomy model utilizes compensatory lung growth to isolate those repair and regeneration signals in order to more clearly define mechanisms of alveolar re-septation. Here, we describe our technique for performing mouse pneumonectomy and sham pneumonectomy. This technique may be utilized in conjunction with lineage tracing or other transgenic mouse models to define molecular and cellular mechanism of lung repair and regeneration.

Mouse pneumonectomy is a commonly employed model of compensatory lung growth. This procedure can be used in conjunction with lineage tracing or transgenic mouse models to elucidate underlying mechanisms.

In humans, disrupted repair and remodeling of injured lung contributes to a host of acute and chronic lung disorders which may ultimately lead to ...

Induction of Accelerated Atherosclerosis in Mice: The "Wire-Injury" Model

Atherosclerosis is a proliferative fibro-inflammatory disease developing in the arterial wall, inducing a deficient blood flow or a lack of blood flow. Moreover, by rupture of the defective vascular wall, atherosclerosis induces occlusive thrombus formation, which represents the main cause of myocardial infarction or stroke and the most frequent cause of death. Despite the advances in the cardiovascular field, many questions remain unanswered, and additional basic research is essential to improve our understanding of the molecular mechanisms during atherosclerosis and its effects. Due to limited clinical studies, there is a need for representative animal models recreating atherosclerotic conditions such as neointima formation after stent implantation, balloon angioplasty, or endarterectomy. Since the mouse presents many advantages and is the most frequently used model for studying molecular processes, the current study proposes an invasive procedure of endothelial denudation, also known as the wire-injury model, which is representative of the human condition of neointima formation in arteries after revascularization procedures.

This study describes an invasive procedure for the induction of accelerated atherosclerosis in mice. In comparison to other methods using electric- or cryo-induced injury, mechanical-induced injury mimics the human condition of restenosis after revascularization therapies and is ideal for the study of the molecular mechanisms involved.

Atherosclerosis is a proliferative fibro-inflammatory disease developing in the arterial wall, inducing a deficient blood flow or a lack of blood flow. ...

Isometric Contractility Measurement of the Mouse Mesenteric Artery Using Wire Myography

The wire myograph technique is used to assess the contractility of vascular smooth muscles in response to depolarization, GPCR agonists/inhibitors and drugs. It is widely used in many studies on the physiological functions of vascular smooth muscle, the pathogenesis of vascular diseases such as hypertension, and the development of smooth muscle relaxant drugs. The mouse is a widely used model animal with a large pool of disease models and genetically modified strains. We introduced this method to measure the isometric contraction of mouse mesenteric artery in detail. A 1.4-mm segment of mouse mesenteric resistance artery was isolated and mounted on a myograph chamber by passing two steel wires through its lumen. After equilibration and normalization steps, the vessel segment was potentiated by a high-K+ solution twice prior to the contraction assay. As an example of the application of this method in drug development, we measured the relaxant effect of a novel natural substance, neoliensinine, isolated from a Chinese herb, embryos of the lotus seed (Nelumbo nucifera Gaertn.) on mouse mesenteric arteries. The vessel segments mounted on the myograph chamber were stimulated with a high-K+ solution. When the force tension reached a stable sustained phase, cumulative doses of neoliensinine were added to the chamber. We found that neoliensinine had a dose-dependent relaxant effect on smooth muscle contraction, thus suggesting that it bears potential activity against hypertension. In addition, as the vessel segment can survive at least 4 hours after mounting and maintain contractility induced by the high-K+ solution for many times, we suggest that the wire myograph system may be used for the time-consuming process of drug screening.

The wire myograph technique is used to investigate vascular smooth muscle functions and screen new drugs. We report a detailed protocol for measuring the isometric contractility of the mouse mesenteric artery and for screening new relaxants of vascular smooth muscle.

The wire myograph technique is used to assess the contractility of vascular smooth muscles in response to depolarization, GPCR agonists/inhibitors and ...

A Preclinical Controlled Cortical Impact Model for Traumatic Hemorrhage Contusion and Neuroinflammation

Cerebral contusion is a severe medical problem affecting millions of people worldwide each year. There is an urgent need to understand the pathophysiological mechanism and to develop effective therapeutic strategy for this devastating neurological disorder. Intraparenchymal hemorrhage and post-traumatic inflammatory response induced by initial physical impact can aggravate microglia/macrophage activation and neuroinflammation which subsequently worsen brain pathology. We provide here a controlled cortical impact (CCI) protocol that can reproduce experimental cortical contusion in mice by using a pneumatic impactor system to deliver mechanical force with controllable magnitude and velocity onto the dural surface. This preclinical model allows researchers to induce moderately severe focal cerebral contusion in mice and to investigate a wide range of post-traumatic pathological progressions including hemorrhage contusion, microglia/macrophage activation, iron toxicity, axonal injury, as well as short-term and long-term neurobehavioral deficits. The present protocol can be useful for exploring the long-term effects of and potential interventions for cerebral contusion.

Intraparenchymal hemorrhage and neuroinflammation accompanied by cerebral contusion can trigger severe secondary brain injury. This protocol details a mouse controlled cortical impact (CCI) model allowing researchers to study hemorrhage contusion and post-traumatic immune responses and explore potential therapeutics.