Name: real-time monitoring and modulation of blood pressure in a rabbit model of ischemic stroke
Uploaded: 2023-02-10T13:15:00
Description: Watch this Scientific Journal Video about Real-Time Monitoring and Modulation of Blood Pressure in a Rabbit Model of Ischemic Stroke at JoVE.com

The research reported in this publication was supported by the National Center for Advancing Translational Sciences of the National Institutes of Health under Award Numbers UL1TR002538 and KL2TR002539 and by Transformational Grant 19TPA34910194 from the American Heart Association.

This protocol is approved by the Institutional Animal Care and Use Committee (University of Utah IACUC Protocol Number 21-09021). Mature New Zealand White rabbits are obtained from commercial vendors.
1. Animal acquisition
<ol>
	<li>Acclimate the animals for the required duration after arrival according to institutional protocol, housing animals socially in a vivarium with standard chow diets. The acclimation period at our institution is 2 weeks.</li>
</ol>
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J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Efficient+creation+of+an+APOE+knockout+rabbit.">Efficient creation of an APOE knockout rabbit.</a> Transgenic Research. 24 (2), 227-235 (2015).</li><li>Abela, G. 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F., Kadirvel, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=From+bench+to+bedside:+Utility+of+the+rabbit+elastase+aneurysm+model+in+pre-clinical+studies+of+intracranial+aneurysm+treatment.">From bench to bedside: Utility of the rabbit elastase aneurysm model in pre-clinical studies of intracranial aneurysm treatment.</a> Journal of Neurointerventional Surgery. 8 (5), 521-525 (2016).</li><li>Zabriskie, M. S., Wang, C., Wang, S., Alexander, M. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Apolipoprotein+E+knockout+rabbit+model+of+intracranial+atherosclerotic+disease.">Apolipoprotein E knockout rabbit model of intracranial atherosclerotic disease.</a> Animal Models and Experimental Medicine. 3 (2), 208-213 (2020).</li><li>Zabriskie, M. S., Cooke, D. L., Wang, C., Alexander, M. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spatially+resolved+transcriptomics+for+evaluation+of+intracranial+vessels+in+a+rabbit+model:+Proof+of+concept.">Spatially resolved transcriptomics for evaluation of intracranial vessels in a rabbit model: Proof of concept.</a> bioRxiv. , (2022).</li><li>Alexander, M. D., Darflinger, R. D., Sun, Z., Cooke, D. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assessment+of+cell+yield+among+different+devices+for+endovascular+biopsy+to+harvest+endothelial+cells.">Assessment of cell yield among different devices for endovascular biopsy to harvest endothelial cells.</a> Biotechniques. 66 (1), 34-36 (2017).</li><li>English, J. 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=A+novel+model+of+large+vessel+ischemic+stroke+in+rabbits:+microcatheter+occlusion+of+the+posterior+cerebral+artery.">A novel model of large vessel ischemic stroke in rabbits: microcatheter occlusion of the posterior cerebral artery.</a> Journal of Neurointerventional Surgery. 7 (5), 363-366 (2015).</li><li>Peng, T. J., Ortega-Guti&#233;rrez, S., de Havenon, A., Petersen, N. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Blood+pressure+management+after+endovascular+thrombectomy.">Blood pressure management after endovascular thrombectomy.</a> Frontiers in Neurology. 12, 723461 (2021).</li><li>Nepal, G., Shrestha, G. S., Shing, Y. K., Muha, A., Bhagat, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Systolic+blood+pressure+variability+following+endovascular+thrombectomy+and+clinical+outcome+in+acute+ischemic+stroke:+A+meta-analysis.">Systolic blood pressure variability following endovascular thrombectomy and clinical outcome in acute ischemic stroke: A meta-analysis.</a> Acta Neurologica Scandinavica. 144 (4), 343-354 (2021).</li><li>Bennett, A. E., 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=Increased+blood+pressure+variability+after+endovascular+thrombectomy+for+acute+stroke+is+associated+with+worse+clinical+outcome.">Increased blood pressure variability after endovascular thrombectomy for acute stroke is associated with worse clinical outcome.</a> Journal of Neurointerventional Surgery. 10 (9), 823-827 (2018).</li><li>de Havenon, 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=Increased+blood+pressure+variability+contributes+to+worse+outcome+after+intracerebral+hemorrhage.">Increased blood pressure variability contributes to worse outcome after intracerebral hemorrhage.</a> Stroke. 49 (8), 1981-1984 (2018).</li></ol>

Substantial progress has been made in the management of IS, particularly considering advances in acute intervention and secondary prevention strategies. However, more work can be done to improve care for IS patients. Limited progress in other aspects of IS treatment, particularly in the realm of neuroprotection, likely results from the limitations in pathophysiological understanding of mechanistic processes at the tissue and molecular level. Impactful data from humans is unrealistic and likely impossible to acquire. In s...

Ischemic stroke (IS) is a leading cause of death and long-term disability worldwide, and its prevalence is projected to increase as society ages1. While substantial advances have been made in acute interventions and secondary prevention strategies, adjunctive neuroprotective treatments have not followed apace2,3,4,5,6,7. Further research is needed into stroke pathobiology because mechanisms by which therapies may or may not prove effective are poorly understood. This is largely due to the heterogeneous nature of the stroke patient population, many of whom have numerous comorbidities that confound analysis1. One driver of limitations in research is the absence of tissue-level data-the gold standard in biomedical research-due to the prohibitive morbidity of sampling tissue from the human central nervous system. Specifically, vascular tissue harvesting in a living human would cause a stroke, so vascular tissue is typically only obtained at autopsy, which is under-representative of the general population and skews toward more advanced disease in elderly patients with concomitant diagnoses.
In such cases, when sufficient human data cannot be utilized, animal models can bridge the data gaps. Large animal models of stroke are limited as most large animals used in research are ungulates having a rete mirabile that prevents direct endovascular access to the cerebral arteries8,9,10,11,12,13,14,15,16,17. Rabbits have a long history of use for the investigation of cardiovascular disease, including intracranial pathologies8,9,10,11,12,13,14,15,16,17. Rabbits present an ideal model for cerebrovascular diseases because they are large enough for endovascular catheterization and lack the rete mirabile that precludes intracranial access in other large mammals9,15,16,17. They have been previously utilized specifically for the investigation of IS through precise and well-controlled occlusion of an intracranial artery with a microcatheter18.
Blood pressure (BP) control, both through modulation of absolute BP or BP variability (BPV), the degree to which arterial BP fluctuates around a mean BP, is an emerging potential therapeutic target for IS patients after reports of worse outcomes in those with poorly controlled BP or BPV19,20,21,22. Mechanistic investigation into how changes lead to poor outcomes in IS patients is lacking. This is partly due to the difficulty in obtaining tissue-level data and performing well-controlled analyses in humans. To test interventions that modulate BP or BPV, animal models must be utilized to overcome these limitations. This report describes the successful pairing of a previously validated rabbit model of IS using controlled occlusion of the posterior cerebral artery in conjunction with continuous intra-arterial measurement of BP18. The method presented here improves on the previous approaches to stroke pathophysiology by applying a validated and reproducible stroke model to a system in which precise measurement and control of BP can be achieved. In this refined model, infarct burden can be assessed with post-procedural histopathologic staining of the harvested brain, which is also amenable to various stains and more advanced analyses such as spatial transcriptomics. Additionally, the occluded posterior circulation artery can also be chosen to be evaluated for morbidity analysis following survival procedures.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>3-0 Silk Suture</td>
			<td>Ethicon</td>
			<td>A184H</td>
			<td></td>
		</tr>
		<tr>
			<td>Buprenorphine</td>
			<td>Sigma-Aldrich</td>
			<td>B9275</td>
			<td></td>
		</tr>
		<tr>
			<td>Catheter</td>
			<td>Terumo</td>
			<td>CG415</td>
			<td>4F glide catheter</td>
		</tr>
		<tr>
			<td>Endovascular Pressure Sensor</td>
			<td>Millar</td>
			<td>SPR-524</td>
			<td></td>
		</tr>
		<tr>
			<td>Euthasol</td>
			<td>Virbac</td>
			<td>PVS111</td>
			<td></td>
		</tr>
		<tr>
			<td>Guidewire</td>
			<td>Terumo</td>
			<td>GR1804</td>
			<td></td>
		</tr>
		<tr>
			<td>Iohexol</td>
			<td>ThermoFisher</td>
			<td>466651000</td>
			<td>Iodinated Contrast</td>
		</tr>
		<tr>
			<td>Ketamine</td>
			<td>Biorbyt</td>
			<td>orb61131</td>
			<td></td>
		</tr>
		<tr>
			<td>LabChart Software</td>
			<td>ADInstruments</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Lidocaine</td>
			<td>Spectrum</td>
			<td>LI102</td>
			<td></td>
		</tr>
		<tr>
			<td>Microcatheter</td>
			<td>Medtronic</td>
			<td>EV3 105-5056</td>
			<td>Marathon Microcatheter</td>
		</tr>
		<tr>
			<td>Microwire</td>
			<td>Medtronic</td>
			<td>EV3 103-0608</td>
			<td>Mirage Microwire</td>
		</tr>
		<tr>
			<td>PowerLab&#160;</td>
			<td>ADInstruments</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Rabbit Brain 2mm Coronal Cutting Matrix</td>
			<td>Ted Pella</td>
			<td>15026</td>
			<td></td>
		</tr>
		<tr>
			<td>Saline</td>
			<td>FisherScientific</td>
			<td>23-535435</td>
			<td></td>
		</tr>
		<tr>
			<td>Sheath</td>
			<td>Merit Medical</td>
			<td>PSI-5F-11</td>
			<td></td>
		</tr>
		<tr>
			<td>Xylazine&#160;</td>
			<td>ThermoFisher</td>
			<td>J61430.14</td>
			<td></td>
		</tr>
	</tbody>
</table>

real-time monitoring and modulation of blood pressure in a rabbit model of ischemic stroke

Control of blood pressure, in terms of both absolute values and its variability, affects outcomes in ischemic stroke patients. However, it remains challenging to identify the mechanisms that lead to poor outcomes or evaluate measures by which these effects can be mitigated because of the prohibitive limitations inherent to human data. In such cases, animal models can be utilized to conduct rigorous and reproducible evaluations of diseases. Here we report refinement of a previously described model of ischemic stroke in rabbits that is augmented with continuous blood pressure recording to assess the impacts of modulation on blood pressure. Under general anesthesia, femoral arteries are exposed through surgical cutdowns to place arterial sheaths bilaterally. Under fluoroscopic visualization and roadmap guidance, a microcatheter is advanced into an artery of the posterior circulation of the brain. An angiogram is performed by injecting the contralateral vertebral artery to confirm occlusion of the target artery. With the occlusive catheter remaining in position for a fixed duration, blood pressure is continuously recorded to allow for tight titration of blood pressure manipulations, whether through mechanical or pharmacological means. At the completion of the occlusion interval, the microcatheter is removed, and the animal is maintained under general anesthesia for a prescribed length of reperfusion. For acute studies, the animal is then euthanized and decapitated. The brain is harvested and processed to measure the infarct volume under light microscopy and further assessed with various histopathological stains or spatial transcriptomic analysis. This protocol provides a reproducible model that can be utilized for more thorough preclinical studies on the effects of blood pressure parameters during ischemic stroke. It also facilitates effective preclinical evaluation of novel neuroprotective interventions that might improve care for ischemic stroke patients.

In the initial experiments with this model, our group successfully achieved the desired outcome of a posterior cerebral or superior cerebellar artery occlusion in 12 out of 14 animals (85.7%). For the experiment, seven males and seven females were studied. The mean animal weight was 3.6 kg (&#177; 0.46 kg). In the two animals in which success was not achieved, profound catheter-induced vasospasm precluded safe access to the intracranial circulation. In one rabbit, intracranial access could not be obtained due to occlusiv...

Watch this Scientific Journal Video about Real-Time Monitoring and Modulation of Blood Pressure in a Rabbit Model of Ischemic Stroke at JoVE.com

Real-Time Monitoring and Modulation of Blood Pressure in a Rabbit Model of Ischemic Stroke

Continuous arterial blood pressure recording allows the investigation of impacts of various hemodynamic parameters. This report demonstrates the application of continuous arterial blood pressure monitoring in a large animal model of ischemic stroke for determination of stroke pathophysiology, impact of different hemodynamic factors, and the assessment of novel treatment approaches.

Control of blood pressure, in terms of both absolute values and its variability, affects outcomes in ischemic stroke patients. However, it remains ...

Understanding the pathophysiology of ischemic stroke is limited due to the absence of high quality tissue data in humans. Since such samples are impossible to acquire, well-controlled animal model studies can serve as a surrogate. The rabbit model used in this protocol provides consistent high-quality data for the interrogation of ischemic stroke.The technique described here allows for precise control and modulation of hemodynamic factors to assess their impact on ischemic stroke pathophysiology. A well-planned procedure can lead to high-quality results, particularly by employing strategies to mitigate vasospasm in the arteries, through a combination of pharmacologic prophylaxis and effective angiographic techniques. To begin, place the rabbit in a supine position on a fluoroscopy compatible operative table.Extend the head as it optimizes positioning for subsequent angiographic views. To mitigate vasospasm, place 0.5 inches of transdermal nitroglycerin on the inside of the ear after induction of anesthesia. After removing the fur from both inguinal regions using electric clippers, prepare the skin with scrubs of chlorhexidine and alcohol.Drape the skin in the usual sterile fashion, and palpate the bilateral femoral arterial pulses. Make a five-centimeter surgical incision with a number 10 blade at the site where lidocaine was injected. Use blunt dissection to expose the neurovascular bundle, and if needed, extend the incision to expose an arterial segment large enough for access.Upon isolation of the neurovascular bundle, drop several drops of 1%lidocaine on the artery to prevent vasospasm. Separate the artery gently from the vein and the adjacent nerve using forceps. Identify the artery by the characteristic appearance of its muscular wall compared to the thin walls of the vein.After isolating the artery, pass the right angle forceps under the vessel. Then grasp two vessel loops with the instrument and gently pass them under the artery. Situate one each at the upstream and downstream ends of the exposed vessel.Subject the artery to gentle traction by pulling the vessel loops, and inspect the vessel for any residual tissue to be removed with gentle dissection, increasing the chances of successful access. After dissecting the vessel and preparing the angiocatheter, drip lidocaine on the vessel again. The artery visibly dilates, increasing the chances of successful access and placement of a sheath using the Seldinger technique.Apply gentle traction to the downstream vessel loop to engorge the artery by reducing outflow and stabilizing the vessel for the access attempt. Next, slowly advance the needle of the angiocatheter into the middle of the exposed arterial segment. On seeing a flash of blood in the angiocatheter and the hub chamber, advance the catheter into the arterial lumen.On successfully placing the angiocatheter, advance a cope microwire through the angiocatheter lumen and into the aorta. Then remove the angiocatheter over the wire and replace it with a five French slim hydrophilic sheath. Confirm the return of the arterial blood through the sidearm tubing by opening the three-way valve.Lock the valve closed, and flush the sheath with 0.9%saline. Secure the sheath hub to the adjacent skin with an additional 3.0 silk suture, and repeat this process for the contralateral femoral artery. Under fluoroscopic visualization, advance a four French glide catheter over a 0.035-inch glide wire inserted through the left femoral sheath.Positioned the tip of the glide catheter in the proximal left vertebral artery. After removing the wire, flush the catheter with heparinized 0.9%saline. Perform angiography by injecting the left vertebral artery with iodinated contrast under lobe magnification to visualize the entire head and neck.For the left vertebral injection, inject 50%contrast, diluted in normal saline, with a gentle crescendo from a three CC syringe. Determine the injection amount by checking the reflux down the right vertebral artery and into the right subclavian artery. During this injection, also note the posterior cerebral artery or superior cerebral artery, one of which will be the target to occlude with the microcatheter.Prepare a 2.4 French flow-directed microcatheter with a 0.010 inch microwire, and make a C shape on the tip of the microwire. Under roadmap guidance, advance the microcatheter inside a four French glide catheter using the right femoral sheath and over the wire into the right vertebral artery. Advance the microcatheter through the cervical segment of the left vertebral artery.To pass the sharp turn as it's best from the V2 to V3 segment, advance the microcatheter alone while the microwire is back proximal to its tip. After passing the sharp turn from V2 to V3, the microcatheter often passes easily to the proximal basal or artery. At this point, advance the microwire and select the desired posterior cerebral and superior cerebellar arteries, as microcatheter injections are not advisable due to the fragile nature of the intracranial arteries.Further advance the microcatheter over the microwire into the target artery and choose a proximal position, as it is typically safest in the posterior to communicate due to its angulation at its origin. A deeper position is feasible in the superior cerebellar artery. Repeat the angiogram by injecting the left vertebral artery catheter with high magnification over the head to confirm occlusion of the target artery.For optimal imaging, inject full-strength contrast, typically no more than one CC, which is adequate for pacification of all intracranial arteries. Gently remove the microwire from the microcatheter under fluoroscopic visualization to confirm a stable position. Place a stopcock on the hub of the microcatheter and close the stopcock to prevent blood loss from retrograde blood flow.Remove the left vertebral catheter to make the left femoral access sheath available. During the ensuing occlusion period, acquire intermittent fluoroscopic images to confirm the stable position of the occlusive microcatheter. Remove the occlusive microcatheter after three hours.And then continue arterial blood pressure measurement and modulation for the additional desired period. Inflate and deflate the balloon catheter in the aorta to monitor the blood pressure variability. In acute procedures with immediate brain harvesting, remove the calvarium in a piecemeal fashion with rongeurs, starting at the occipital ridge and working anteriorly until the brain can be harvested intact.Place the brain in formalin or flash freeze, depending on the type of tissue analysis desired. In all the animals, the brain was successfully harvested and histopathological analysis was carried out, demonstrating infarction in the right cerebellum. The blood pressure was traced from a Fogarty balloon catheter placed in the infrarenal aorta, and the data from approximately one hour of monitoring demonstrates real-time arterial pressure changes with changes in balloon inflation.Short-term tracing of the blood pressure demonstrates the pressure changes throughout the cardiac cycle. Additionally, small rapid changes were noted from respiratory variability, which is physiologically normal. An immediate near-doubling of measured blood pressure was noted following the inflation of the balloon.While attempting this procedure, meticulous blunt dissection and dripping lidocaine to prevent vasospasm during access of the angiocatheter is critical. Also, angiography of the left vertebral artery provides a roadmap for efficient endovascular access to the targeted intracranial artery. Hemodynamics can be modulated in pharmacological ways or by inflating a balloon catheter in the aorta.The harvested brain specimens can be analyzed with a variety of techniques, such as histopathology or spatial transcriptomics.

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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 ...

Real-time Cytotoxicity Assays in Human Whole Blood

A live cell-based whole blood cytotoxicity assay (WCA) that allows access to temporal information of the overall cell cytotoxicity is developed with high-throughput cell positioning technology. The targeted tumor cell populations are first preprogrammed to immobilization into an array format, and labeled with green fluorescent cytosolic dyes. Following the cell array formation, antibody drugs are added in combination with human whole blood. Propidium iodide (PI) is then added to assess cell death. The cell array is analyzed with an automatic imaging system. While cytosolic dye labels the targeted tumor cell populations, PI labels the dead tumor cell populations. Thus, the percentage of target cancer cell killing can be quantified by calculating the number of surviving targeted cells to the number of dead targeted cells. With this method, researchers are able to access time-dependent and dose-dependent cell cytotoxicity information. Remarkably, no hazardous radiochemicals are used. The WCA presented here has been tested with lymphoma, leukemia, and solid tumor cell lines. Therefore, WCA allows researchers to assess drug efficacy in a highly relevant ex&#160;vivo condition.

The whole blood cytotoxicity assay (WCA) is a cytotoxicity assay developed by incorporating high-throughput cell positioning technology with fluorescence microscopy and automated image processing. Here, we describe how lymphoma cells treated with an anti-CD20 antibody can be analyzed real-time in human whole blood to provide quantitative cellular cytotoxicity analysis.

A live cell-based whole blood cytotoxicity assay (WCA) that allows access to temporal information of the overall cell cytotoxicity is developed with ...

Embolic Middle Cerebral Artery Occlusion (MCAO) for Ischemic Stroke with Homologous Blood Clots in Rats

Clinically, thrombolytic therapy with use of recombinant tissue plasminogen activator (tPA) remains the most effective treatment for acute ischemic stroke. However, the use of tPA is limited by its narrow therapeutic window and by increased risk of hemorrhagic transformation. There is an urgent need to develop suitable stroke models to study new thrombolytic agents and strategies for treatment of ischemic stroke. At present, two major types of ischemic stroke models have been developed in rats and mice: intraluminal suture MCAO and embolic MCAO. Although MCAO models via the intraluminal suture technique have been widely used in mechanism-driven stroke research, these suture models do not mimic the clinical situation and are not suitable for thrombolytic studies. Among these models, the embolic MCAO model closely mimics human ischemic stroke and is suitable for preclinical investigation of thrombolytic therapy. This embolic model was first developed in rats by Overgaard et al.1 in 1992 and further characterized by Zhang et al. in 19972. Although embolic MCAO has gained increasing attention, there are technical problems faced by many laboratories. To meet increasing needs for thrombolytic research, we present a highly reproducible model of embolic MCAO in the rat, which can develop a predictable infarct volume within the MCA territory. In brief, a modified PE-50 tube is gently advanced from the external carotid artery (ECA) into the lumen of the internal carotid artery (ICA) until the tip of the catheter reaches the origin of the MCA. Through the catheter, a single homologous blood clot is placed at the origin of the MCA. To identify the success of MCA occlusion, regional cerebral blood flow was monitored, neurological deficits and infarct volumes were measured. The techniques presented in this paper should help investigators to overcome technical problems for establishing this model for stroke research.

Embolic Middle Cerebral Artery Occlusion MCAO for Ischemic Stroke with Homologous Blood Clots in Rats

In this paper, we demonstrate a standard method for producing an embolic middle cerebral artery occlusion with homologous blood clots (fibrin-rich) in adult rat. This model closely mimics human ischemic stroke and is suitable for preclinical study of thrombolytic therapy for ischemic stroke.

Clinically, thrombolytic therapy with use of recombinant tissue plasminogen activator (tPA) remains the most effective treatment for acute ischemic ...

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 ...

PET Imaging of Neuroinflammation Using [11C]DPA-713 in a Mouse Model of Ischemic Stroke

Neuroinflammation is central to the pathological cascade following ischemic stroke. Non-invasive molecular imaging methods have the potential to provide critical insights into the temporal dynamics and role of certain neuroimmune interactions in stroke. Specifically, Positron Emission Tomography (PET) imaging of translocator protein 18 kDa (TSPO), a marker of activated microglia and peripheral myeloid-lineage cells, provides a means to detect and track neuroinflammation in vivo. Here, we present a method to accurately quantify neuroinflammation using [11C]N,N-Diethyl-2-[2-(4-methoxyphenyl)-5,7-dimethylpyrazolo[1,5-a]pyrimidin-3-yl]acetamide ([11C]DPA-713), a promising second generation TSPO-PET radiotracer, in distal middle cerebral artery occlusion (dMCAO) compared to sham-operated mice. MRI was performed 2 days post-dMCAO surgery to confirm stroke and define the infarct location and volume. PET/Computed Tomography (CT) imaging was carried out 6 days post-dMCAO to capture the peak increase in TSPO levels following stroke. Quantitation of PET images was conducted to assess the uptake of [11C]DPA-713 in the brain and spleen of dMCAO and sham mice to assess central and peripheral levels of inflammation. In vivo [11C]DPA-713 brain uptake was confirmed using ex vivo autoradiography.

PET Imaging of Neuroinflammation Using [11C]DPA-713 in a Mouse Model of Ischemic Stroke

Positron Emission Tomography (PET) imaging of translocator protein 18 kDa (TSPO) provides a non-invasive means to visualize the dynamic role of neuroinflammation in the development and progression of brain diseases. This protocol describes TSPO-PET and ex vivo autoradiography to detect neuroinflammation in a mouse model of ischemic stroke.

Neuroinflammation is central to the pathological cascade following ischemic stroke. Non-invasive molecular imaging methods have the potential to provide ...

Real-time Pressure-volume Analysis of Acute Myocardial Infarction in Mice

Acute myocardial infarction can lead to acute heart failure and cardiogenic shock. The evaluation of hemodynamics is critical for the evaluation of any potential therapeutic approach directed against acute left ventricular (LV) dysfunction. Current imaging modalities (e.g., echocardiography and magnetic resonance imaging) have several limitations since data on LV pressure cannot directly be measured. LV catheterization in mice undergoing coronary artery occlusion could serve as a novel method for a real-time evaluation of LV function.
At the beginning of the procedure, mice were anesthetized followed by endotracheal intubation. For LV catheterization, the right carotid artery was exposed via middle-neck incision. The catheter was introduced and placed into the LV cavity. Left thoracotomy was conducted and the left main coronary artery (LCA) was ligated. To induce reperfusion, the suture was released after 45 min. Pressure-volume data was recorded at all times.
Ligation of the LCA caused a decrease in LV systolic function as evidenced by a 30% reduction in stroke volume, LV ejection fraction (EF), and cardiac output. Maximum dP/dt as a parameter for LV contractility was also significantly reduced and diastolic function was severely impaired (minimum dP/dt -40%). Reperfusion over a period of 20 min did not lead to a complete recovery of LV function.
Real-time pressure-volume analysis served as a valid procedure for monitoring cardiac function during acute myocardial infarction in mice. Maintaining stable anesthesia and a standardized surgical approach was crucial to ensure valid results. As the early phase of acute myocardial infarction is critical for morbidity and mortality, the delineated method could be beneficial for preclinical evaluation of new strategies for cardioprotection.

Acute myocardial infarction in mice induces acute but incompletely characterized changes in left ventricular (LV) function. LV catheterization in mice undergoing coronary artery occlusion serves as a novel method for a real-time evaluation of LV function.

Acute myocardial infarction can lead to acute heart failure and cardiogenic shock. The evaluation of hemodynamics is critical for the evaluation of any ...

A Rabbit Venous Interposition Model Mimicking Revascularization Surgery using Vein Grafts to Assess Intimal Hyperplasia under Arterial Blood Pressure

Although vein grafts have been commonly used as autologous grafts in revascularization surgeries for ischemic diseases, the long-term patency remains poor because of the acceleration of intimal hyperplasia due to the exposure to arterial blood pressure. The present protocol is designed for the establishment of experimental venous intimal hyperplasia by interposing rabbit jugular veins to the ipsilateral carotid arteries. The protocol does not require surgical procedures deep in the body trunk and the extent of the incision is limited, which is less invasive for the animals, allowing long-term observation after implantation. This simple procedure enables researchers to investigate strategies to attenuate the progression of intimal hyperplasia of the implanted vein grafts. Using this protocol, we reported the effects transduction of microRNA-145 (miR-145), which is known to control the phenotype of vascular smooth muscle cells (VSMCs) from the proliferative to the contractile state, into harvested vein grafts. We confirmed the attenuation of intimal hyperplasia of vein grafts by transducing miR-145 before implantation surgery through the phenotype change of the VSMCs. Here we report a less invasive experimental platform to investigate the strategies that can be used to attenuate intimal hyperplasia of vein grafts in revascularization surgeries.

The present protocol aims to experimentally create venous intimal hyperplasia by subjecting veins to arterial blood pressure for developing strategies to attenuate venous intimal hyperplasia following revascularization surgery using vein grafts.

Although vein grafts have been commonly used as autologous grafts in revascularization surgeries for ischemic diseases, the long-term patency remains poor ...

Real-Time Monitoring of Neurocritical Patients with Diffuse Optical Spectroscopies

Neurophysiological monitoring is an important goal in the treatment of neurocritical patients, as it may prevent secondary damage and directly impact morbidity and mortality rates. However, there is currently a lack of suitable non-invasive, real-time technologies for continuous monitoring of cerebral physiology at the bedside. Diffuse optical techniques have been proposed as a potential tool for bedside measurements of cerebral blood flow and cerebral oxygenation in case of neurocritical patients. Diffuse optical spectroscopies have been previously explored to monitor patients in several clinical scenarios ranging from neonatal monitoring to cerebrovascular interventions in adults. However, the feasibility of the technique to aid clinicians by providing real-time information at the bedside remains largely unaddressed. Here, we report the translation of a diffuse optical system for continuous real-time monitoring of cerebral blood flow, cerebral oxygenation, and cerebral oxygen metabolism during intensive care. The real-time feature of the instrument could enable treatment strategies based on patient-specific cerebral physiology rather than relying on surrogate metrics, such as arterial blood pressure. By providing real-time information on the cerebral circulation at different time scales with relatively cheap and portable instrumentation, this approach may be especially useful in low-budget hospitals, in remote areas and for&#160;monitoring in open fields (e.g., defense and sports).

Presented here is a protocol for non-invasively monitoring cerebral hemodynamics of neurocritical patients in real-time and at the bedside using diffuse optics. Specifically, the proposed protocol uses a hybrid diffuse optical systems to detect and display real-time information on cerebral oxygenation, cerebral blood flow and cerebral metabolism.

Neurophysiological monitoring is an important goal in the treatment of neurocritical patients, as it may prevent secondary damage and directly impact ...

Real-Time Assessment of Spinal Cord Microperfusion in a Porcine Model of Ischemia/Reperfusion

Spinal cord injury is a devastating complication of aortic repair. Despite developments for the prevention and treatment of spinal cord injury, its incidence is still considerably high and therefore, influences patient outcome. Microcirculation plays a key role in tissue perfusion and oxygen supply and is often dissociated from macrohemodynamics. Thus, direct evaluation of spinal cord microcirculation is essential for the development of microcirculation-targeted therapies and the evaluation of existing approaches in regard to spinal cord microcirculation. However, most of the methods do not provide real-time assessment of spinal cord microcirculation. The aim of this study is to describe a standardized protocol for real-time spinal cord microcirculatory evaluation using laser-Doppler needle probes directly inserted in the spinal cord. We used a porcine model of ischemia/reperfusion to induce deterioration of the spinal cord microcirculation. In addition, a fluorescent microsphere injection technique was used. Initially, animals were anesthetized and mechanically ventilated. Thereafter, laser-Doppler needle probe insertion was performed, followed by the placement of cerebrospinal fluid drainage. A median sternotomy was performed for exposure of the descending aorta to perform aortic cross-clamping. Ischemia/reperfusion was induced by supra-celiac aortic cross-clamping for a total of 48 min, followed by reperfusion and hemodynamic stabilization. Laser-Doppler Flux was performed in parallel with macrohemodynamic evaluation. In addition, automated cerebrospinal fluid drainage was used to maintain a stable cerebrospinal pressure. After completion of the protocol, animals were sacrificed, and the spinal cord was harvested for histopathological and microsphere analysis. The protocol reveals the feasibility of spinal cord microperfusion measurements using laser-Doppler probes and shows a marked decrease during ischemia as well as recovery after reperfusion. Results showed comparable behavior to fluorescent microsphere evaluation. In conclusion, this new protocol might provide a useful large animal model for future studies using real-time spinal cord microperfusion assessment in ischemia/reperfusion conditions.

Spinal cord microcirculation plays a pivotal role in spinal cord injury. Most methods do not allow real-time assessment of spinal cord microcirculation, which is essential for the development of microcirculation-targeted therapies. Here, we propose a protocol using Laser-Doppler-Flow Needle probes in a large animal model of ischemia/reperfusion.

Spinal cord injury is a devastating complication of aortic repair. Despite developments for the prevention and treatment of spinal cord injury, its ...