Name: measuring post-stroke cerebral edema, infarct zone and blood-brain barrier breakdown in a single set of rodent brain samples
Uploaded: 2020-10-23T13:30:00
Description: Watch this Scientific Journal Video about Measuring Post-Stroke Cerebral Edema, Infarct Zone and Blood-Brain Barrier Breakdown in a Single Set of Rodent Brain Samples at JoVE.com

We thank Maryna Kuscheriava, Maksym Kryvonosov, Daryna Yakumenko and Evgenia Goncharyk of the Department of Physiology, Faculty of Biology, Ecology, and Medicine, Oles Honchar, Dnipro University, Dnipro, Ukraine for their support and helpful contributions to our discussions. The data obtained are part of Ruslan Kuts&#8217;s PhD thesis.

The following procedures were conducted according to the recommendations of the Declaration of Helsinki and Tokyo and the Guidelines for the Use of Experimental Animals of the European Community. The experiments were also approved by the Animal Care Committee at the Ben-Gurion University of the Negev.
1. Preparing rats for the experimental procedure
<ol>
	<li>Select adult male Sprague-Dawley rats without overt pathology, each weighing between 300 and 350 g.</li>
	<li>Maintain all rats at roo...

The principal goal of the present protocol was to demonstrate consistent measurements of three main parameters of ischemic injury: IZ, BE and BBB permeability. Previous studies in this field have demonstrated the possibility of performing one or two of these parameters together in the same sample. Besides the cost reduction that this three-part method offers, it also provides a more desirable bioethical model that limits the number of animals that must be operated on and subsequently euthanized. As in all histological te...

One of the most common causes of morbidity and mortality worldwide is stroke. Globally, ischemic stroke represents 68% of all stroke cases, while in the United States ischemic stroke accounts for 87% of stroke cases1,2. It is estimated that the economic burden of stroke reaches $34 billion in the United States2 and &#8364;45 billion in the European Union3. Animal models of stroke are necessary to study its pathophysiology, develop new methods for evaluation, and propose new therapeutic options4.
Ischemic stroke occurs with occlusion of a major cerebral artery, usually the middle cerebral artery or one of its branches5. Thus, models of ischemic stroke have historically involved middle cerebral artery occlusion (MCAO)6,7,8,9,10,11,12. Following MCAO, neurological injury is most commonly assessed by measuring infarct zone (IZ) using a 2,3,5-triphenyltetrazolium chloride (TTC) staining method13, brain edema (BE) using drying or calculating hemispheric volumes14,15,16, and blood brain barrier (BBB) permeability by a spectrometry technique using Evans blue staining17,18,19.
The traditional MCAO method uses separate sets of brains for each of the three brain measurements. For a large sample size, this results in a significant number of euthanized animals, with added ethical and financial considerations. An alternative method to alleviate these costs would involve measurements of all three parameters in a single set of post-MCAO rodent brains.
Previous attempts have been made to measure combinations of parameters in the same brain sample. Simultaneous immunofluorescent staining methods20 as well as other molecular and biochemical analyses21 have been described after TTC staining in the same brain sample. We have previously calculated brain hemisphere volumes to assess brain edema and performed TTC staining to calculate infarct zone in the same brain set15.
In the present protocol, we present a modified MCAO technique that measures ischemic brain injury through determining IZ, BE, and BBB permeability in the same set of rodent brains. IZ is measured by TTC staining, BE is determined by calculating hemispheric volume, and BBB permeability is obtained by spectrometry methods19. In this protocol, we used a modified MCAO model, based on direct insertion and fixation of the monofilament catheter into the internal carotid artery (ICA) and further blocking of blood flow to the middle cerebral artery (MCA)22. This modified method shows a decreased rate of mortality and morbidity compared to the traditional MCAO method16,22.
This new approach provides a financially-sound and ethical model for measuring neurological injury after MCAO. This assessment of the main parameters of ischemic brain injury will help to comprehensively investigate its pathophysiology.

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			<td>2 mL Syringe</td>
			<td>Braun</td>
			<td>4606027V</td>
			<td></td>
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			<td>2% chlorhexidine in 70% alcohol solution</td>
			<td>Sigma-Aldrich</td>
			<td>500 cc</td>
			<td>Provides general antisepsis of the skin in the operatory field</td>
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		<tr>
			<td>27 G Needle with Syringe</td>
			<td>Braun</td>
			<td>305620</td>
			<td></td>
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			<td>3-0 Silk sutures</td>
			<td>Henry Schein</td>
			<td>1007842</td>
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			<td>4-0 Nylon suture</td>
			<td>4-00</td>
			<td></td>
			<td></td>
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			<td>Brain &#38; Tissue Matrices</td>
			<td>Sigma-Aldrich</td>
			<td>15013</td>
			<td></td>
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			<td>Cannula Venflon 22 G</td>
			<td>KD-FIX</td>
			<td>183603985447</td>
			<td></td>
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			<td>Centrifuge Sigma 2-16P</td>
			<td>Sigma-Aldrich</td>
			<td>Sigma 2-16P</td>
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			<td>Compact Analytical Balances</td>
			<td>Sigma-Aldrich</td>
			<td>HR-AZ/HR-A</td>
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			<td>Digital weighing scale</td>
			<td>Sigma-Aldrich</td>
			<td>Rs 4,000</td>
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			<td>Dissecting scissors</td>
			<td>Sigma-Aldrich</td>
			<td>Z265969</td>
			<td></td>
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			<td>Eppendorf pipette</td>
			<td>Sigma-Aldrich</td>
			<td>Z683884</td>
			<td></td>
		</tr>
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			<td>Eppendorf tube</td>
			<td>Sigma-Aldrich</td>
			<td>EP0030119460</td>
			<td></td>
		</tr>
		<tr>
			<td>Fluorescence detector</td>
			<td>Tecan, M&#228;nnedorf Switzerland</td>
			<td>Model: Infinite 200 PRO multimode reader</td>
			<td>Optional.</td>
		</tr>
		<tr>
			<td>Fluorescence detector</td>
			<td>Molecular Devices LLC</td>
			<td>VWR cat. # 10822 512 SpectraMax Paradigm Multi Mode Microplate Reader Base Instrument</td>
			<td>Optional.</td>
		</tr>
		<tr>
			<td>Gauze sponges</td>
			<td>Fisher</td>
			<td>22-362-178</td>
			<td></td>
		</tr>
		<tr>
			<td>Heater with thermometer</td>
			<td>Heatingpad-1</td>
			<td>Model: HEATINGPAD-1/2</td>
			<td></td>
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		<tr>
			<td>Hemostatic microclips</td>
			<td>Sigma-Aldrich</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Horizon-XL</td>
			<td>Mennen Medical Ltd</td>
			<td></td>
			<td></td>
		</tr>
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			<td>Infusion cuff</td>
			<td>ABN</td>
			<td>IC-500</td>
			<td></td>
		</tr>
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			<td>Micro forceps</td>
			<td>Sigma-Aldrich</td>
			<td></td>
			<td></td>
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			<td>Micro scissors</td>
			<td>Sigma-Aldrich</td>
			<td></td>
			<td></td>
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			<td>Multiset</td>
			<td>Teva Medical</td>
			<td>998702</td>
			<td></td>
		</tr>
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			<td>Olympus BX 40 microscope</td>
			<td>Olympus</td>
			<td></td>
			<td></td>
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			<td>Operating forceps</td>
			<td>Sigma-Aldrich</td>
			<td></td>
			<td></td>
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			<td>Operating scissors</td>
			<td>Sigma-Aldrich</td>
			<td></td>
			<td></td>
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			<td>Optical scanner</td>
			<td>Canon</td>
			<td>Cano Scan 4200F</td>
			<td>Resolution 3200 x 6400 dpi</td>
		</tr>
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			<td>Petri dishes</td>
			<td>Sigma-Aldrich</td>
			<td>P5606</td>
			<td></td>
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			<td>Purina Chow</td>
			<td>Purina</td>
			<td>5001</td>
			<td>Rodent laboratory chow given to rats, mice and hamster is a life-cycle nutrition that has been used in biomedical research for over 5 decades. Provided to rats ad libitum in this experiment.</td>
		</tr>
		<tr>
			<td>Rat cages</td>
			<td>Techniplast</td>
			<td>2000P</td>
			<td>Conventional housing for rodents. Cages were used for housing rats throughout the experiment</td>
		</tr>
		<tr>
			<td>Scalpel blades #11</td>
			<td>Sigma-Aldrich</td>
			<td>S2771</td>
			<td></td>
		</tr>
		<tr>
			<td>Software</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Adobe Photoshop CS2 for Windows</td>
			<td>Adobe</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>ImageJ 1.37v</td>
			<td>NIH</td>
			<td></td>
			<td>The source code is freely available. The author, Wayne Rasband (wayne@codon.nih.gov), is at the Research Services Branch, National Institute of Mental Health, Bethesda, Maryland, USA</td>
		</tr>
		<tr>
			<td>Office 365 ProPlus</td>
			<td>Microsoft</td>
			<td>-</td>
			<td>Microsoft Office Excel</td>
		</tr>
		<tr>
			<td>Windows 10</td>
			<td>Microsoft</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Reagents</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>2,3,5-Triphenyltetrazolium chloride</td>
			<td>Sigma-Aldrich</td>
			<td>298-96-4</td>
			<td></td>
		</tr>
		<tr>
			<td>50% trichloroacetic acid</td>
			<td>Sigma-Aldrich</td>
			<td>76-03-9</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol 96 %</td>
			<td>Romical</td>
			<td></td>
			<td>Flammable liquid</td>
		</tr>
		<tr>
			<td>Evans blue 2%</td>
			<td>Sigma-Aldrich</td>
			<td>314-13-6</td>
			<td></td>
		</tr>
		<tr>
			<td>Isoflurane, USP 100%</td>
			<td>Piramamal Critical Care, Inc</td>
			<td>NDC 66794-017</td>
			<td></td>
		</tr>
	</tbody>
</table>

measuring post-stroke cerebral edema, infarct zone and blood-brain barrier breakdown in a single set of rodent brain samples

One of the most common causes of morbidity and mortality worldwide is ischemic stroke. Historically, an animal model used to stimulate ischemic stroke involves middle cerebral artery occlusion (MCAO). Infarct zone, brain edema and blood-brain barrier (BBB) breakdown are measured as parameters that reflect the extent of brain injury after MCAO. A significant limitation to this method is that these measurements are normally obtained in different rat brain samples, leading to ethical and financial burdens due to the large number of rats that need to be euthanized for an appropriate sample size. Here we present a method to accurately assess brain injury following MCAO by measuring infarct zone, brain edema and BBB permeability in the same set of rat brains. This novel technique provides a more efficient way to evaluate the pathophysiology of stroke.

Infarct zone measurement
An independent-sample t-test indicated that 19 rats that underwent permanent MCAO demonstrated a significant increase in brain infarct volume compared to the 16 sham-operated rats (MCAO=7.49% &#177; 3.57 vs. Sham = 0.31% &#177; 1.9, t(28.49) = 7.56, p &#60; 0.01 (see Figure 2A)). The data is expressed as a mean percentage of the contralateral hemisphere &#177; SD.
Brain...

Watch this Scientific Journal Video about Measuring Post-Stroke Cerebral Edema, Infarct Zone and Blood-Brain Barrier Breakdown in a Single Set of Rodent Brain Samples at JoVE.com

Measuring Post-Stroke Cerebral Edema, Infarct Zone and Blood-Brain Barrier Breakdown in a Single Set of Rodent Brain Samples

This protocol describes a novel technique of measuring the three most important parameters of ischemic brain injury on the same set of rodent brain samples. Using only one brain sample is highly advantageous in terms of ethical and economic costs.

One of the most common causes of morbidity and mortality worldwide is ischemic stroke. Historically, an animal model used to stimulate ischemic stroke ...

In the present protocol, we present a modified middle cerebral artery occlusion technique that measures ischemic brain injury to determinate an infarct zone, brain edema, and BBB permeability in the same set of rodent brains. In terms of ethical and economic costs, the main advantage of this technique is that only one brain sample is required for all three measurements. This assessment of the main parameters of ischemic brain injury will help to comprehensively investigate pathophysiology of ischemic stroke.To begin, remove the rat brain, and cut 2 millimeter thick horizontal sections with a 0.009-inch stainless steel, uncoated, single edge razor blade. Place the sections in 0.005%TTC and incubate them for 30 minutes at 37 degrees Celsius, then place the brain tissue on the microscope slides and perform optical scanning of the six brain slices with a resolution of 1600 x 1600 DPI. Use a photo editor to add a blue filter to the images.After opening the software, go to image, adjustments, and channel mixer. Select blue as the output channel and check monochrome, then click okay. Save the image in the JPEG file format.Use the polygon selection tool in ImageJ version 1.37 to select each hemisphere of each of the six brain slices and save it as a separate image file. To calculate the infarct volume and brain edema, use a macro to convert the pixels in the image to white or black, based on a threshold. Then, close all files and use a second macro to compare the number of white and black pixels to determine the infarct volume and brain edema.Copy the raw data to a spreadsheet. When calculating infarct volume, correct for tissue swelling by using the ratios of ipsilateral and contralateral cerebral hemispheres. Express the brain edema areas as a percentage of the standard areas of the unaffected contralateral hemisphere.Determine blood brain barrier disruption 24 hours after occlusion. Divide the right and left hemispheres into six slices and put each slice into a microcentrifuge tube. Homogenize each slice of the brain tissue in trichloroacetic acid, using 4 milliliters of 50%trichloroacetic acid per gram of brain tissue.Centrifuge the samples at 10, 000 times G for 20 minutes, then transfer the supernatant into a fresh tube and dilute it 1:3 with 96%ethanol. Perform luminescence spectrophotometry with a plate reader. An independent sample t-test indicated that 19 rats that underwent permanent middle cerebral artery occlusion, or MCAO, demonstrated a significant increase in brain infarct volume compared to the 16 sham operated rats.The rats that underwent permanent MCAO also demonstrated a significant increase in the extent of brain edema and blood brain barrier breakdown after 24 hours, compared to the sham operated animals. When attempting this procedure, it is important to ensure that chemical concentration comply with the protocol. This protocol makes it possible to evaluate all three parameters of ischemic damage in one sample of the brain.

measuring-post-stroke-cerebral-edema-infarct-zone-blood-brain-barrier

Research

JoVE Journal

Neuroscience

Functional Neuroimaging Using Ultrasonic Blood-brain Barrier Disruption and Manganese-enhanced MRI

Although mice are the dominant model system for studying the genetic and molecular underpinnings of neuroscience, functional neuroimaging in mice remains technically challenging. One approach, Activation-Induced Manganese-enhanced MRI (AIM MRI), has been used successfully to map neuronal activity in rodents 1-5. In AIM MRI, Mn2+ acts a calcium analog and accumulates in depolarized neurons 6,7. Because Mn2+ shortens the T1 tissue property, regions of elevated neuronal activity will enhance in MRI. Furthermore, Mn2+ clears slowly from the activated regions; therefore, stimulation can be performed outside the magnet prior to imaging, enabling greater experimental flexibility. However, because Mn2+ does not readily cross the blood-brain barrier (BBB), the need to open the BBB has limited the use of AIM MRI, especially in mice.
One tool for opening the BBB is ultrasound. Though potentially damaging, if ultrasound is administered in combination with gas-filled microbubbles (i.e., ultrasound contrast agents), the acoustic pressure required for BBB opening is considerably lower. This combination of ultrasound and microbubbles can be used to reliably open the BBB without causing tissue damage 8-11.
Here, a method is presented for performing AIM MRI by using microbubbles and ultrasound to open the BBB. After an intravenous injection of perflutren microbubbles, an unfocused pulsed ultrasound beam is applied to the shaved mouse head for 3 minutes. For simplicity, we refer to this technique of BBB Opening with Microbubbles and UltraSound as BOMUS 12. Using BOMUS to open the BBB throughout both cerebral hemispheres, manganese is administered to the whole mouse brain. After experimental stimulation of the lightly sedated mice, AIM MRI is used to map the neuronal response.
To demonstrate this approach, herein BOMUS and AIM MRI are used to map unilateral mechanical stimulation of the vibrissae in lightly sedated mice 13. Because BOMUS can open the BBB throughout both hemispheres, the unstimulated side of the brain is used to control for nonspecific background stimulation. The resultant 3D activation map agrees well with published representations of the vibrissae regions of the barrel field cortex 14. The ultrasonic opening of the BBB is fast, noninvasive, and reversible; and thus this approach is suitable for high-throughput and/or longitudinal studies in awake mice.

A technique is described for broadly opening the blood-brain barrier in the mouse using microbubbles and ultrasound. Using this technique, manganese can be administered to the mouse brain. Because manganese is an MRI contrast agent that accumulates in depolarized neurons, this approach enables imaging of neuronal activity.

Although mice are the dominant model system for studying the genetic and molecular underpinnings of neuroscience, functional neuroimaging in mice remains ...

Assessment of Blood-brain Barrier Permeability by Intravenous Infusion of FITC-labeled Albumin in a Mouse Model of Neurodegenerative Disease

Disruption of blood-brain barrier (BBB) integrity is a common feature for different neurological and neurodegenerative diseases. Although the interplay between perturbed BBB homeostasis and the pathogenesis of brain disorders needs further investigation, the development and validation of a reliable procedure to accurately detect BBB alterations may be crucial and represent a useful tool for potentially predicting disease progression and developing targeted therapeutic strategies.
Here, we present an easy and efficient procedure for evaluating BBB leakage in a neurodegenerative condition like that occurring in a preclinical mouse model of Huntington disease, in which defects in the permeability of BBB are clearly detectable precociously in the disease. Specifically, the high molecular weight fluorescein isothiocyanate labelled (FITC)-albumin, which is able to cross the BBB only when the latter is impaired, is acutely infused into a mouse jugular vein and its distribution in the vascular or parenchymal districts is then determined by fluorescence microscopy.
Accumulation of green fluorescent-albumin in the brain parenchyma functions as an index of aberrant BBB permeability and, when quantitated by using Image J processing software, is reported as Green Fluorescence Intensity.

In this study, we present an easy and efficient procedure for evaluating the disruption of the blood-brain barrier under neurodegenerative conditions. To achieve our objective, we infused high molecular weight fluorescein isothiocyanate labelled (FITC)-albumin into mouse jugular vein and evaluated its leakage into the brain parenchyma by fluorescence microscopy.

Disruption of blood-brain barrier (BBB) integrity is a common feature for different neurological and neurodegenerative diseases. Although the interplay ...

An In Vivo Blood-brain Barrier Permeability Assay in Mice Using Fluorescently Labeled Tracers

Blood-brain barrier (BBB) is a specialized barrier that protects the brain microenvironment from toxins and pathogens in the circulation and maintains brain homeostasis. The principal sites of the barrier are endothelial cells of the brain capillaries whose barrier function results from tight intercellular junctions and efflux transporters expressed on the plasma membrane. This function is regulated by pericytes and astrocytes that together form the neurovascular unit (NVU). Several neurological diseases such as stroke, Alzheimer&#39;s disease (AD), brain tumors are associated with an impaired BBB function. Assessment of the BBB permeability is therefore crucial in evaluating the severity of the neurological disease and the success of the treatment strategies employed.
We present here a simple yet robust permeability assay that have been successfully applied to several mouse models both, genetic and experimental. The method is highly quantitative and objective in comparison to the tracer fluorescence analysis by microscopy that is commonly applied. In this method, mice are injected intraperitoneally with a mix of aqueous inert fluorescent tracers followed by anesthetizing the mice. Cardiac perfusion of the animals is performed prior to harvesting brain, kidneys or other organs. Organs are homogenized and centrifuged followed by fluorescence measurement from the supernatant. Blood drawn from the cardiac puncture just before perfusion serves for normalization purpose to the vascular compartment. The tissue fluorescence is normalized to the wet weight and serum fluorescence to obtain a quantitative tracer permeability index. For additional confirmation, the contralateral hemi-brain preserved for immunohistochemistry can be utilized for tracer fluorescence visualization purposes.

An In Vivo Blood-brain Barrier Permeability Assay in Mice Using Fluorescently Labeled Tracers

Here we present a mouse brain vascular permeability assay using intraperitoneal injection of fluorescent tracers followed by perfusion that is applicable to animal models of blood-brain barrier dysfunction. One hemi-brain is used for assessing permeability quantitatively and the other for tracer visualization/immunostaining. The procedure takes 5 - 6 h for 10 mice.

Blood-brain barrier (BBB) is a specialized barrier that protects the brain microenvironment from toxins and pathogens in the circulation and maintains ...

An In Vivo Assessment of Blood-Brain Barrier Disruption in a Rat Model of Ischemic Stroke

Ischemic stroke leads to vasogenic cerebral edema and subsequent primary brain injury, which is mediated through destruction of the blood-brain barrier (BBB). Rats with induced ischemic stroke were established and used as in vivo models to investigate the functional integrity of the BBB. Spectrophotometric detection of Evans blue (EB) in the brain samples with ischemic injury could provide reliable justification for the research and development of novel therapeutic modalities. This method generates reproducible results, and is applicable in any laboratory without a need for special equipment. Here, we present a visualized and technical guideline on the detection of the extravasation of EB following induction of ischemic stroke in rats.

An In Vivo Assessment of Blood-Brain Barrier Disruption in a Rat Model of Ischemic Stroke

The overall goal of this procedure is to provide a highly reproducible technique for in vivo assessment of the blood-brain barrier disruption in rat models of ischemic stroke.

Ischemic stroke leads to vasogenic cerebral edema and subsequent primary brain injury, which is mediated through destruction of the blood-brain barrier ...

Effects of Blast-induced Neurotrauma on Pressurized Rodent Middle Cerebral Arteries

Though there have been studies on the histopathological and behavioral effects of blast exposure, fewer have been dedicated to blast&#39;s cerebral vascular effects. Impact (i.e., non-blast) traumatic brain injury (TBI) is known to decrease pressure autoregulation in the cerebral vasculature in both humans and experimental animals. The hypothesis that blast-induced traumatic brain injury (bTBI), like impact TBI, results in impaired cerebral vascular reactivity was tested by measuring myogenic dilatory responses to reduced intravascular pressure in rodent middle cerebral arterial (MCA) segments from rats subjected to mild bTBI using an Advanced Blast Simulator (ABS) shock tube. Adult, male Sprague-Dawley rats were anesthetized, intubated, ventilated and prepared for Sham bTBI (identical manipulation and anesthesia except for blast injury) or mild bTBI. Rats were randomly assigned to receive Sham bTBI or mild bTBI followed by sacrifice 30 or 60 min post-injury. Immediately after bTBI, righting reflex (RR) suppression times were assessed, euthanasia at the time points post-injury was completed, the brain was harvested and the individual MCA segments were collected, mounted and pressurized. As the intraluminal pressure perfused through the arterial segments was reduced in 20 mmHg increments from 100 to 20 mmHg, MCA diameters were measured and recorded. With decreasing intraluminal pressure, MCA diameters steadily increased significantly above baseline in the Sham bTBI groups while MCA dilator responses were significantly reduced (p &#60; 0.05) in both bTBI groups as evidenced by the impaired, smaller MCA diameters recorded for the bTBI groups. In addition, RR suppression in the bTBI groups was significantly (p &#60; 0.05) higher than in the Sham bTBI groups. MCA&#39;s collected from the Sham bTBI groups exhibited typical vasodilatory properties to decreases in intraluminal pressure while MCA&#39;s collected following bTBI exhibited significantly impaired myogenic vasodilatory responses to reduced pressure that persisted for at least 60 min after bTBI.

Here, we present a protocol to describe methods for ex vivo vascular reactivity determination following a primary blast traumatic brain injury (bTBI) using isolated, pressurized, rodent middle cerebral arterial (MCA) segments. bTBI induction is accomplished using a shock tube, also known as an Advanced Blast Simulator (ABS) device.

Though there have been studies on the histopathological and behavioral effects of blast exposure, fewer have been dedicated to blast&#39;s cerebral ...

A Benchtop Approach to the Location Specific Blood Brain Barrier Opening using Focused Ultrasound in a Rat Model

Stereotaxic surgery is the gold standard for localized drug and gene delivery to the rodent brain. This technique has many advantages over systemic delivery including precise localization to a target brain region and reduction of off target side effects. However, stereotaxic surgery is highly invasive which limits its translational efficacy, requires long recovery times, and provides challenges when targeting multiple brain regions. Focused ultrasound (FUS) can be used in combination with circulating microbubbles to transiently open the blood brain barrier (BBB) in millimeter sized regions. This allows intracranial localization of systemically delivered agents that cannot normally cross the BBB. This technique provides a noninvasive alternative to stereotaxic surgery. However, to date this technique has yet to be widely adopted in neuroscience laboratories due to the limited access to equipment and standardized methods. The overall goal of this protocol is to provide a benchtop approach to FUS BBB opening (BBBO) that is affordable and reproducible and can therefore be easily adopted by any laboratory.

Focused ultrasound with microbubble agents can open the blood brain barrier focally and transiently. This technique has been used to deliver a wide range of agents across the blood brain barrier. This article provides a detailed protocol for the localized delivery to the rodent brain with or without MRI guidance.

Stereotaxic surgery is the gold standard for localized drug and gene delivery to the rodent brain. This technique has many advantages over systemic ...

A High-Throughput Image-Guided Stereotactic Neuronavigation and Focused Ultrasound System for Blood-Brain Barrier Opening in Rodents

The blood-brain barrier (BBB) has been a major hurdle for the treatment of various brain diseases. Endothelial cells, connected by tight junctions, form a physiological barrier preventing large molecules (&#62;500 Da) from entering the brain tissue. Microbubble-mediated focused ultrasound (FUS) can be used to induce a transient local BBB opening, allowing larger drugs to enter the brain parenchyma.
In addition to large-scale clinical devices for clinical translation, preclinical research for therapy response assessment of drug candidates requires dedicated small animal ultrasound setups for targeted BBB opening. Preferably, these systems allow high-throughput workflows with both high-spatial precision as well as integrated cavitation monitoring, while still being cost effective in both initial investment and running costs.
Here, we present a bioluminescence and X-ray guided stereotactic small animal FUS system that is based on commercially available components and fulfills the aforementioned requirements. A particular emphasis has been placed on a high degree of automation facilitating the challenges typically encountered in high-volume preclinical drug evaluation studies. Examples of these challenges are the need for standardization in order to ensure data reproducibility, reduce intra-group variability, reduce sample size and thus comply with ethical requirements and decrease unnecessary workload. The proposed BBB system has been validated in the scope of BBB opening facilitated drug delivery trials on patient-derived xenograft models of glioblastoma multiforme and diffuse midline glioma.

The blood-brain barrier (BBB) can be temporarily disrupted with microbubble-mediated focused ultrasound (FUS). Here, we describe a step-by-step protocol for high-throughput BBB opening in vivo using a modular FUS system accessible for non-ultrasound experts.

The blood-brain barrier (BBB) has been a major hurdle for the treatment of various brain diseases. Endothelial cells, connected by tight junctions, form a ...

Focused Ultrasound Induced Blood-Brain Barrier Opening for Targeting Brain Structures and Evaluating Chemogenetic Neuromodulation

Acoustically Targeted Chemogenetics (ATAC) allows for the noninvasive control of specific neural circuits. ATAC achieves such control through a combination of focused ultrasound (FUS) induced blood-brain barrier opening (FUS-BBBO), gene delivery with adeno-associated viral (AAV) vectors, and activation of cellular signaling with engineered, chemogenetic, protein receptors and their cognate ligands. With ATAC, it is possible to transduce both large and small brain regions with millimeter precision using a single noninvasive ultrasound application. This transduction can later allow for a long-term, noninvasive, device-free neuromodulation in freely moving animals using a drug. Since FUS-BBBO, AAVs, and chemogenetics have been used in multiple animals, ATAC should also be scalable for the use in other animal species. This paper expands upon a previously published protocol and outlines how to optimize the gene delivery with FUS-BBBO to small brain regions with MRI-guidance but without a need for a complicated MRI-compatible FUS device. The protocol, also, describes the design of mouse targeting and restraint components that can be 3D-printed by any lab and can be easily modified for different species or custom equipment. To aid reproducibility, the protocol describes in detail how the microbubbles, AAVs, and venipuncture were used in ATAC development. Finally, an example data is shown to guide the preliminary investigations of studies utilizing ATAC.

This protocol delineates steps necessary for the gene delivery through focused ultrasound blood brain barrier (BBB) opening, evaluation of the resulting gene expression, and measurement of neuromodulation activity of chemogenetic receptors through histological tests.

Acoustically Targeted Chemogenetics (ATAC) allows for the noninvasive control of specific neural circuits. ATAC achieves such control through a ...

Transendothelial Resistance Measurement to Assess Cell Barrier Integrity

Barrier Functional Integrity Recording on bEnd.3 Vascular Endothelial Cells via Transendothelial Electrical Resistance Detection

The blood-brain barrier (BBB) is a dynamic physiological structure composed of microvascular endothelial cells, astrocytes, and pericytes. By coordinating the interaction between restricted transit of harmful substances, nutrient absorption, and metabolite clearance in the brain, the BBB is essential in preserving central nervous system homeostasis. Building in vitro models of the BBB is a valuable tool for exploring the pathophysiology of neurological disorders and creating pharmacological treatments. This study describes a procedure for creating an in vitro monolayer BBB cell model by seeding bEnd.3 cells into the upper chamber of a 24-well plate. To assess the integrity of cell barrier function, the conventional epithelial cell voltmeter was used to record the transmembrane electrical resistance of normal cells and CoCl2-induced hypoxic cells in real-time. We anticipate that the above experiments will provide effective ideas for the creation of in vitro models of BBB and drugs to treat disorders of central nervous system diseases.

Author Spotlight: Applications of TEER Detection to Assess Cell Barrier Integrity 

This protocol describes a dependable and efficient in vitro model of the brain blood barrier. The method uses mouse cerebral vascular endothelial cells bEnd.3 and measures transmembrane electrical resistance.

The blood-brain barrier (BBB) is a dynamic physiological structure composed of microvascular endothelial cells, astrocytes, and pericytes. By coordinating ...

A 3D Blood-Brain Barrier Model Derived from Human Pluripotent Stem-Cells

Reconstruction of the Blood-Brain Barrier In Vitro to Model and Therapeutically Target Neurological Disease

The blood-brain barrier (BBB) is a key physiological component of the central nervous system (CNS), maintaining nutrients, clearing waste, and protecting the brain from pathogens. The inherent barrier properties of the BBB pose a challenge for therapeutic drug delivery into the CNS to treat neurological diseases. Impaired BBB function has been related to neurological disease. Cerebral amyloid angiopathy (CAA), the deposition of amyloid in the cerebral vasculature leading to a compromised BBB, is a co-morbidity in most cases of Alzheimer&#39;s disease (AD), suggesting that BBB dysfunction or breakdown may be involved in neurodegeneration. Due to limited access to human BBB tissue, the mechanisms that contribute to proper BBB function and BBB degeneration remain unknown. To address these limitations, we have developed a human pluripotent stem cell-derived BBB (iBBB) by incorporating endothelial cells, pericytes, and astrocytes in a 3D matrix. The iBBB self-assembles to recapitulate the anatomy and cellular interactions present in the BBB. Seeding iBBBs with amyloid captures key aspects of CAA. Additionally, the iBBB offers a flexible platform to modulate genetic and environmental factors implicated in cerebrovascular disease and neurodegeneration, to investigate how genetics and lifestyle affect disease risk. Finally, the iBBB can be used for drug screening and medicinal chemistry studies to optimize therapeutic&#160;delivery to the CNS. In this protocol, we describe the differentiation of the three types of cells (endothelial cells, pericytes, and astrocytes) arising from human pluripotent stem cells, how to assemble the differentiated cells into the iBBB, and how to model CAA in vitro using exogenous amyloid. This model overcomes the challenge of studying live human brain tissue with a system that has both biological fidelity and experimental flexibility, and enables the interrogation of the human BBB and its role in neurodegeneration.

Author Spotlight: A Personalized Approach Towards Investigating Alzheimer's Disease Using an In Vitro Blood-Brain Barrier Model 

The blood-brain barrier (BBB) has a crucial role in sustaining a stable and healthy brain environment. BBB dysfunction is associated with many neurological diseases. We have developed a 3D, stem-cell-derived model of the BBB to investigate cerebrovascular pathology, BBB integrity, and how the BBB is altered by genetics and disease.

The blood-brain barrier (BBB) is a key physiological component of the central nervous system (CNS), maintaining nutrients, clearing waste, and protecting ...