Name: a triple primary cell culture model of the human blood-brain barrier for studying ischemic stroke in vitro
Uploaded: 2022-10-06T14:05:00
Description: Watch this Scientific Journal Video about A Triple Primary Cell Culture Model of the Human Blood-Brain Barrier for Studying Ischemic Stroke In Vitro at JoVE.com

This work was supported by the National Institutes of Health (NIH) grants MH128022, MH122235, MH072567, MH122235, HL126559, DA044579, DA039576, DA040537, DA050528, and DA047157.

NOTE: See the Table of Materials for details related to all cells, materials, equipment, and solutions used in this protocol.
1. Triple cell culture BBB model setting
<ol>
	<li>Seeding pericytes
	<ol>
		<li>Cultivate HBVP in T75 culture flasks with an activated surface for cell adhesion within a 5% CO2 incubator at 37 &#176;C until confluent. Once confluence is reached, aspirate the old pericyte medium and wash the cells with 5 mL of warm Dulbecco...

<ol>
	<li>Mozaffarian, 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=Heart+disease+and+stroke+statistics-2016+update:+a+report+from+the+American+Heart+Association.">Heart disease and stroke statistics-2016 update: a report from the American Heart Association.</a> Circulation. 133 (94), 38 (2016).</li><li>Yousufuddin, M., Young, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Aging+and+ischemic+stroke.">Aging and ischemic stroke.</a> Aging. 11 (9), 2542-2544 (2019).</li><li>Donkor, E. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stroke+in+the+21st+century:+a+snapshot+of+the+burden,+epidemiology,+and+quality+of+life.">Stroke in the 21st century: a snapshot of the burden, epidemiology, and quality of life.</a> Stroke Research and Treatment. , 3238165 (2018).</li><li>Kadry, H., Noorani, B., Cucullo, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+blood-brain+barrier+overview+on+structure,+function,+impairment,+and+biomarkers+of+integrity.">A blood-brain barrier overview on structure, function, impairment, and biomarkers of integrity.</a> Fluids and Barriers of the CNS. 17 (1), 69 (2020).</li><li>Brown, L. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pericytes+and+neurovascular+function+in+the+healthy+and+diseased+brain.">Pericytes and neurovascular function in the healthy and diseased brain.</a> Frontiers in Cellular Neuroscience. 13, 282 (2019).</li><li>Cabezas, R., 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=Astrocytic+modulation+of+blood+brain+barrier:+perspectives+on+Parkinson's+disease.">Astrocytic modulation of blood brain barrier: perspectives on Parkinson's disease.</a> Frontiers in Cellular Neuroscience. 8, 211 (2014).</li><li>Abdullahi, W., Tripathi, D., Ronaldson, P. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Blood-brain+barrier+dysfunction+in+ischemic+stroke:+targeting+tight+junctions+and+transporters+for+vascular+protection.">Blood-brain barrier dysfunction in ischemic stroke: targeting tight junctions and transporters for vascular protection.</a> American Journal of Physiology-Cell Physiology. 315 (3), 343-356 (2018).</li><li>Candelario-Jalil, E., Dijkhuizen, R. M., Magnus, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neuroinflammation,+stroke,+blood-brain+barrier+dysfunction,+and+imaging+modalities.">Neuroinflammation, stroke, blood-brain barrier dysfunction, and imaging modalities.</a> Stroke. 53 (5), 1473-1486 (2022).</li><li>He, Y., Yao, Y., Tsirka, S. E., Cao, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell-culture+models+of+the+blood-brain+barrier.">Cell-culture models of the blood-brain barrier.</a> Stroke. 45 (8), 2514-2526 (2014).</li><li>Thomsen, L. B., Burkhart, A., Moos, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+triple+culture+model+of+the+blood-brain+barrier+using+porcine+brain+endothelial+cells,+astrocytes+and+pericytes.">A triple culture model of the blood-brain barrier using porcine brain endothelial cells, astrocytes and pericytes.</a> PLoS One. 10 (8), 0134765 (2015).</li><li>Song, Y., Cai, X., Du, D., Dutta, P., Lin, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+blood-brain+barrier+models+for+in+vitro+biological+analysis:+one+cell+type+vs+three+cell+types.">Comparison of blood-brain barrier models for in vitro biological analysis: one cell type vs three cell types.</a> ACS Applied Bio Materials. 2 (3), 1050-1055 (2019).</li><li>Xu, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Silver+nanoparticles+induce+tight+junction+disruption+and+astrocyte+neurotoxicity+in+a+rat+blood-brain+barrier+primary+triple+coculture+model.">Silver nanoparticles induce tight junction disruption and astrocyte neurotoxicity in a rat blood-brain barrier primary triple coculture model.</a> International Journal of Nanomedicine. 10, 6105-6118 (2015).</li><li>Appelt-Menzel, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Establishment+of+a+human+blood-brain+barrier+co-culture+model+mimicking+the+neurovascular+unit+using+induced+pluri-+and+multipotent+stem+cells.">Establishment of a human blood-brain barrier co-culture model mimicking the neurovascular unit using induced pluri- and multipotent stem cells.</a> Stem Cell Reports. 8 (4), 894-906 (2017).</li><li>Zhang, Y., 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=Rational+construction+of+a+reversible+arylazo-based+NIR+probe+for+cycling+hypoxia+imaging+in+vivo.">Rational construction of a reversible arylazo-based NIR probe for cycling hypoxia imaging in vivo.</a> Nature Communications. 12 (1), 2772 (2021).</li><li>Palacio-Casta&#241;eda, V., Kooijman, L., Venzac, B., Verdurmen, W. P. R., Le Gac, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Metabolic+switching+of+tumor+cells+under+hypoxic+conditions+in+a+tumor-on-a-chip+model.">Metabolic switching of tumor cells under hypoxic conditions in a tumor-on-a-chip model.</a> Micromachines. 11 (4), 382 (2020).</li><li>Ramsauer, M., Krause, D., Dermietzel, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Angiogenesis+of+the+blood-brain+barrier+in+vitro+and+the+function+of+cerebral+pericytes.">Angiogenesis of the blood-brain barrier in vitro and the function of cerebral pericytes.</a> FASEB Journal. 16 (10), 1274-1276 (2002).</li><li>Lyck, R., 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=ALCAM+(CD166)+is+involved+in+extravasation+of+monocytes+rather+than+T+cells+across+the+blood-brain+barrier.">ALCAM (CD166) is involved in extravasation of monocytes rather than T cells across the blood-brain barrier.</a> Journal of Cerebral Blood Flow &amp; Metabolism. 37 (8), 2894-2909 (2017).</li><li>Rizzi, 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=A+triple+culture+cell+system+modeling+the+human+blood-brain+barrier.">A triple culture cell system modeling the human blood-brain barrier.</a> Journal of Visualized Experiments. (177), (2021).</li><li>Kumar, S., Shaw, L., Lawrence, C., Lea, R., Alder, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=P50:+Developing+a+physiologically+relevant+blood+brain+barrier+model+for+the+study+of+drug+disposition+in+glioma.">P50: Developing a physiologically relevant blood brain barrier model for the study of drug disposition in glioma.</a> Neuro-Oncology. 16 (6), (2014).</li><li>Stone, N. L., England, T. J., O'Sullivan, S. E. <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+transwell+blood+brain+barrier+model+using+primary+human+cells.">A novel transwell blood brain barrier model using primary human cells.</a> Frontiers in Cellular Neuroscience. 13, 230 (2019).</li><li>Al Ahmad, A., Taboada, C. B., Gassmann, M., Ogunshola, O. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Astrocytes+and+pericytes+differentially+modulate+blood-brain+barrier+characteristics+during+development+and+hypoxic+insult.">Astrocytes and pericytes differentially modulate blood-brain barrier characteristics during development and hypoxic insult.</a> Journal of Cerebral Blood Flow &amp; Metabolism. 31 (2), 693-705 (2011).</li></ol>

In this protocol, we describe a method to set up a reliable triple endothelial cell-pericyte-astrocyte culture BBB model for&#160;studying BBB dysfunction in the setting of ischemic stroke in vitro. Considering that pericytes are the nearest neighbors of endothelial cells in vivo, HBVP are plated on the underside of the well-inserts in this model16. Although this configuration lacks the direct cell-to-cell communication between astrocytes and endothelial cells, this arrangement a...

Stroke is one of the leading causes of death and long-term disability worldwide1. The incidence of stroke rapidly increases with age, doubling every 10 years after the age of 552. Ischemic stroke occurs as a result of cerebral blood flow disruption due to thrombotic and embolic events, which encompasses more than 80% of all stroke cases3. Even now, there are relatively few treatment options available to minimize tissue death following ischemic stroke. The treatments that do exist are time-sensitive and consequentially do not always lead to good clinical outcomes. Therefore, research on complex cellular mechanisms of ischemic stroke that affect poststroke recovery is urgently needed.
The BBB is a dynamic interface for the exchange of molecules between the blood and the brain parenchyma. Structurally, the BBB is comprised of brain microvascular endothelial cells interconnected by junctional complexes surrounded by a basement membrane, pericytes, and astrocytic endfeet4. Pericytes and astrocytes play an essential role in the maintenance of BBB integrity through the secretion of various factors necessary for the formation of strong, tight junctions5,6. The breakdown of the BBB is one of the hallmarks of ischemic stroke. Acute inflammatory response and oxidative stress associated with cerebral ischemia results in the disruption of tight junction protein complexes and dysregulated crosstalk between astrocytes, pericytes, and endothelial cells, which leads to increased paracellular solute permeability across the BBB7. BBB dysfunction further promotes the formation of brain edema and increases the risk of hemorrhagic transformation8. Considering all of the above, there is great interest in understanding the molecular and cellular changes that occur at the BBB level during and after ischemic stroke.
Although many in vitro BBB models have been developed over recent decades and used in a variety of studies, none of them can fully replicate in vivo conditions9. While some models are based on endothelial cell monolayers cultured on well-insert permeable supports alone or in combination with pericytes or astrocytes, only more recent studies have introduced triple cell culture model designs. Almost all existing triple culture BBB models incorporate primary brain endothelial cells along with astrocytes and pericytes isolated from animal species or cells derived from human pluripotent stem cells10,11,12,13.
Recognizing the need to better recapitulate the human BBB in vitro, we established a triple cell culture in vitro BBB model composed of human brain microvascular endothelial cells (HBMEC), primary human astrocytes (HA), and primary human brain vascular pericytes (HBVP). This triple culture BBB model is set up on 6-well plate, polyester membrane inserts with 0.4 &#181;m pore size. These well-inserts provide an optimal environment for cell attachment and enable easy access to both apical (blood) and basolateral (brain) compartments for medium sampling or compound application. The features of this proposed triple cell culture BBB model are assessed by measuring TEER and paracellular flux post OGD mimicking ischemic stroke in vitro, with a shortage of oxygen (&#60;1% O2) and nutrients (by using glucose-free medium) achieved by using a humidified, sealed chamber. Additionally, induced ischemic-like conditions in this model are accurately verified by direct visualization of hypoxic cells.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>24 mm Transwell with 0.4 &#181;m Pore Polyester Membrane Insert</td>
			<td>Corning</td>
			<td>3450</td>
			<td></td>
		</tr>
		<tr>
			<td>35 mm Glass Bottom Dishes</td>
			<td>MatTek Life Sciences (FISHERSCI)</td>
			<td>P35GC-1.5-14-C</td>
			<td></td>
		</tr>
		<tr>
			<td>Astrocyte Medium</td>
			<td>Science Cell</td>
			<td>1801</td>
			<td></td>
		</tr>
		<tr>
			<td>Attachment Factor</td>
			<td>Cell Systems (Fisher Scientific)</td>
			<td>4Z0-201</td>
			<td></td>
		</tr>
		<tr>
			<td>BD 60 mL Syringe</td>
			<td>BD</td>
			<td>309653</td>
			<td></td>
		</tr>
		<tr>
			<td>BrainPhys Imaging Optimized Medium</td>
			<td>STEMCELL Technologies</td>
			<td>5791</td>
			<td></td>
		</tr>
		<tr>
			<td>Complete Classic Medium With Serum and CultureBoost</td>
			<td>4Z0-500</td>
			<td>Cell Systems</td>
			<td></td>
		</tr>
		<tr>
			<td>Corning 50 mL PP Centrifuge Tubes (Conical Bottom with CentriStar Cap</td>
			<td>VWR</td>
			<td>430829</td>
			<td></td>
		</tr>
		<tr>
			<td>Corning 75cm&#178; U-Shaped Canted Neck Not Treated Cell Culture Flask&#160;</td>
			<td>Corning</td>
			<td>431464U</td>
			<td></td>
		</tr>
		<tr>
			<td>Corning CellBIND 96-well Flat Clear Bottom Black Polystyrene Microplates</td>
			<td>Corning</td>
			<td>3340</td>
			<td></td>
		</tr>
		<tr>
			<td>Countes Cell Counting Chamber Slides</td>
			<td>Thermo Fisher Scientific</td>
			<td>C10228</td>
			<td></td>
		</tr>
		<tr>
			<td>Countess II FL Automated Cell Counter</td>
			<td>Thermo Fisher Scientific</td>
			<td>ZGEXSCCOUNTESS2FL</td>
			<td></td>
		</tr>
		<tr>
			<td>Decon CiDehol 70 Isopropyl Alcohol Solution&#160;</td>
			<td>Fisher Scientific&#160;</td>
			<td>04-355-71</td>
			<td></td>
		</tr>
		<tr>
			<td>Disposable Petri Dishes</td>
			<td>VWR</td>
			<td>25384-088</td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM Medium (No glucose, No glutamine, No phenol red)</td>
			<td>ThermoFisher</td>
			<td>A14430-01</td>
			<td>Glucose-free medium</td>
		</tr>
		<tr>
			<td>DPBS (No Calcium, No Magnesium)</td>
			<td>ThermoFisher</td>
			<td>14190250</td>
			<td></td>
		</tr>
		<tr>
			<td>EBM Endothelial Cell Growth Basal Medium, Phenol Red Free, 500 mL</td>
			<td>Lonza</td>
			<td>CC-3129</td>
			<td></td>
		</tr>
		<tr>
			<td>EVOM2 Epithelial Volt/Ohm (TEER) Meter with STX2 electrodes</td>
			<td>World Precison Instruments</td>
			<td>NC9792051</td>
			<td>Epithelial voltohmmeter&#160;</td>
		</tr>
		<tr>
			<td>Fluorescein isothiocyanate&#8211;dextran (wt 20,000)</td>
			<td>Millipore Sigma</td>
			<td>FD20-250MG</td>
			<td></td>
		</tr>
		<tr>
			<td>Fluorescein isothiocyanate&#8211;dextran (wt 70,000)</td>
			<td>Millipore Sigma</td>
			<td>FD70S-250MG</td>
			<td></td>
		</tr>
		<tr>
			<td>Fluorview FV3000 Confocal Microscope</td>
			<td>Olympus</td>
			<td>FV3000</td>
			<td></td>
		</tr>
		<tr>
			<td>Gas Tank (95% N2, 5% CO2)</td>
			<td>Airgas</td>
			<td>X02NI95C2003071</td>
			<td></td>
		</tr>
		<tr>
			<td>HBSS (No calcium, No magnesium, no phenol red)</td>
			<td>Thermofisher</td>
			<td>14025092</td>
			<td></td>
		</tr>
		<tr>
			<td>Hoechst 33342, Trihydrochloride, Trihydrate - 10 mg/mL Solution in Water</td>
			<td>ThermoFisher</td>
			<td>H3570</td>
			<td></td>
		</tr>
		<tr>
			<td>Human Astrocytes</td>
			<td>Science Cell</td>
			<td>1800</td>
			<td></td>
		</tr>
		<tr>
			<td>Human Brain Vascular Pericytes</td>
			<td>Science Cell</td>
			<td>1200</td>
			<td></td>
		</tr>
		<tr>
			<td>Hypoxia Incubator Chamber</td>
			<td>STEMCELL Technologies</td>
			<td>27310</td>
			<td></td>
		</tr>
		<tr>
			<td>Image-iT Green Hypoxia Reagent</td>
			<td>ThermoFisher</td>
			<td>I14834</td>
			<td></td>
		</tr>
		<tr>
			<td>Pericyte Medium</td>
			<td>Science Cell</td>
			<td>1201</td>
			<td></td>
		</tr>
		<tr>
			<td>Primary Human Brain Microvascular Endothelial Cells</td>
			<td>ACBRI 376</td>
			<td>Cell Systems</td>
			<td></td>
		</tr>
		<tr>
			<td>Rocking Platform Shaker, Double</td>
			<td>VWR</td>
			<td>10860-658</td>
			<td></td>
		</tr>
		<tr>
			<td>Single Flow Meter</td>
			<td>STEMCELL Technologies</td>
			<td>27311</td>
			<td></td>
		</tr>
		<tr>
			<td>SpectraMax iD3 Microplate Reader</td>
			<td>Molecular Devices</td>
			<td>75886-128</td>
			<td></td>
		</tr>
		<tr>
			<td>Syringe Filter, 25 mm, 0.22 &#956;m, PVDF, Sterile</td>
			<td>NEST Scientific</td>
			<td>380121</td>
			<td></td>
		</tr>
		<tr>
			<td>TPP Mutli-well Plates (6 wells)</td>
			<td>MidSci</td>
			<td>TP92406</td>
			<td></td>
		</tr>
		<tr>
			<td>TPP Tissue Culture Flasks T-75 Flasks</td>
			<td>MidSci</td>
			<td>TP90075</td>
			<td>Flasks with activated surface for cell adhesion</td>
		</tr>
		<tr>
			<td>Trypsin-EDTA (0.25%), phenol red</td>
			<td>ThermoFisher</td>
			<td>25200056</td>
			<td></td>
		</tr>
		<tr>
			<td>UltraPure Distilled Water</td>
			<td>Invitrogen (Life Technologies)</td>
			<td>10977-015</td>
			<td></td>
		</tr>
		<tr>
			<td>Uno Stage Top Incubator-</td>
			<td>Oko Lab</td>
			<td>UNO-T-H-CO2-TTL</td>
			<td></td>
		</tr>
	</tbody>
</table>

a triple primary cell culture model of the human blood-brain barrier for studying ischemic stroke in vitro

Ischemic stroke is a major cause of death and disability worldwide with limited therapeutic options. The neuropathology of ischemic stroke is characterized by an interruption in blood supply to the brain leading to cell death and cognitive dysfunction. During and after ischemic stroke, blood-brain barrier (BBB) dysfunction facilitates injury progression and contributes to poor patient recovery. Current BBB models primarily include endothelial monocultures and double co-cultures with either astrocytes or pericytes.
Such models lack the ability to fully imitate a dynamic brain microenvironment, which is essential for cell-to-cell communication. Additionally, commonly used BBB models often contain immortalized human endothelial cells or animal-derived (rodent, porcine, or bovine) cell cultures that pose translational limitations. This paper describes a novel well-insert-based BBB model containing only primary human cells (brain microvascular endothelial cells, astrocytes, and brain vascular pericytes) enabling the investigation of ischemic brain injury in vitro. 
The effects of oxygen-glucose deprivation (OGD) on barrier integrity were assessed by passive permeability, transendothelial electrical resistance (TEER) measurements,and direct visualization of hypoxic cells. The presented protocol offers a distinct advantage inmimicking the intercellular environment of the BBB in vivo, serving as a more realistic in vitro BBB model for developing new therapeutic strategies in the setting of ischemic brain injury.

To examine the effects of astrocytes and pericytes on the barrier function of HBMEC, we constructed the triple cell culture BBB model on cell culture inserts (Figure 1A) along with HBMEC monoculture and two double co-culture models as controls (Figure 1B). Double co-culture controls included a non-contact co-culture of HBMEC with HA and contact co-culture of HBMEC with HBVP. After 6 days in co-culture, all experimental setups were subjected to OGD for 4 h. The b...

Watch this Scientific Journal Video about A Triple Primary Cell Culture Model of the Human Blood-Brain Barrier for Studying Ischemic Stroke In Vitro at JoVE.com

A Triple Primary Cell Culture Model of the Human Blood-Brain Barrier for Studying Ischemic Stroke In Vitro

Here, we describe the method for establishing a triple cell culture model of the blood-brain barrier based on primary human brain microvascular endothelial cells, astrocytes, and pericytes. This multicellular model is suitable for studies of neurovascular unit dysfunction during ischemic stroke in vitro or for the screening of drug candidates.

A Triple Primary Cell Culture Model of the Human Blood-Brain Barrier for Studying Ischemic Stroke In Vitro

Ischemic stroke is a major cause of death and disability worldwide with limited therapeutic options. The neuropathology of ischemic stroke is ...

Our protocol recognizes the need to better recapitulate the human blood-brain barrier in vitro for the study of complex cellular mechanisms that affect post-stroke recovery. Our triple model exhibits robust integrity which is partly related to large compartmenting of well inserts, allowing us to decrease the change frequency and avoid disruption of populations. Our model is a great tool for studying the molecular and cellular changes that occur at the blood-brain barrier during and after ischemic stroke.Our protocol allows for the discovery of novel targets and therapeutics to improve post-stroke recovery. Current treatments for ischemic stroke are time sensitive and consequentially are not always effective. Begin by cultivating HBVP in T75 culture flasks with an activated surface for cell adhesion within a 5%carbon dioxide incubator at 37 degrees Celsius until confluent.Once confluence is reached, aspirate the old pericyte medium and wash the cells with five milliliters of warm Dulbecco's PBS. Aspirate the Dulbecco's PBS and detach the cells from the flask using a combination of four milliliters of warm trypsin EDTA solution and one milliliter of Dulbecco's PBS. Incubate the flask for five minutes at 37 degree Celsius in a carbon dioxide incubator.View under a microscope to confirm whether the cells are detached from the flask. Add five milliliters of warm pericyte medium containing 2%FBS to the flask and transfer the detached cells to a 50 milliliter centrifuge tube. Centrifuge the cell suspension for three minutes at 200 g allowing the cells to form a pellet in the bottom of the tube.Aspirate the medium from the tube ensuring the cell pellet remains intact. Re-suspend the cell pellet in pericyte medium. Calculate the amount of medium depending on the confluence of the cells and the number of well inserts needed.Take 10 microliters of the re-suspended cells, place them into a cell counting slide, and count the number of cells. Determine the cell density and seed 300, 000 cells per insert in one milliliter of pericyte medium onto the abluminal side of the well inserts. Cultivate primary human astrocytes using the astrocyte medium containing 2%FBS as described in the text manuscript.Determine the cell density and seed 300, 000 cells per well onto the bottom of the tissue culture six-well plates. Cover the plate to prevent evaporation and incubate overnight. Similarly, cultivate HBMEC in tissue culture dishes using complete classic medium containing 10%FBS as described in the text manuscript.Take out the tissue culture six-well plates containing astrocytes and the well inserts containing pericytes from the incubator. Aspirate the astrocyte medium from the tissue culture six-well plates and add one milliliter of pericyte medium and one milliliter of astrocyte medium to each well. Aspirate the pericyte medium from the well inserts and place them into the tissue culture six-well plates containing the seeded astrocytes.Seed HBMEC at a density of 300, 000 cells per well in two milliliters of complete classic medium onto the apical side of the same well inserts. Wash the cells thrice with Dulbecco's PBS. For triple cell cultures subjected to oxygen-glucose deprivation, add glucose-free medium to both the apical and basolateral compartments.Replace the culture medium with fresh medium and normoxic control cell cultures. Place control triple cultures in the 5%carbon dioxide incubator at 37 degrees Celsius. Place a Petri dish containing 20 milliliters of sterile water in the hypoxia incubator chamber to provide adequate humidification of the cultures.Open the chamber by releasing the ring clamp, then arrange the cell cultures on the shelves. Seal the chamber by securing the ring clamp. Open the inlet and outlet ports of the chamber and attach the tubing from the top of the chamber's flow meter.Attach the tubing from the bottom of the flow meter to the gas tank via an air filter. Open the tank flow control valve by turning it counterclockwise to allow minimum gas flow. Slowly open the pressure regulator valve by turning clockwise.Flush the chamber with the gas mixture for five minutes at a flow rate of 20 liters per minute. Disconnect the chamber from the gas source and close both white plastic clamps firmly. Turn off the tank flow control valve by turning clockwise.Close the pressure regulator valve by turning counterclockwise. Place the hypoxia chamber in a conventional incubator set at 37 degrees Celsius for four hours. Place the sterilized TEER instrument into the biosafety cabinet and plug the electrodes into the epithelial volt ohm meter.Sterilize the electrodes in 30 milliliters of 70%isopropyl alcohol solution for a minimum of 30 minutes. Turn on the TEER instrument and set the function to ohms. Remove the electrodes from the 70%isopropyl alcohol solution and place them in 20 milliliters of Dulbecco's PBS for a minimum of 30 minutes until the digital readout on the TEER device reads zero ohms.Insert the long prong of the electrode through one of the three openings in the well insert hangar of the blank well insert control lowering it until it touches the bottom of the well. Ensure that the short prong is resting above the apical culture on the bottom of the well insert. Wait until the digital readout values on the TEER instrument level off before recording the value.Place the electrodes back into Dulbecco's PBS to wash them between measurements. Continue to collect all the TEER measurements for two more blank well insert controls. Collect the TEER measurements of the sample plates as demonstrated earlier.Once all the measurements have been taken place the electrode back into the 70%isopropyl alcohol solution for 30 minutes. Then disconnect the electrodes from the TEER instrument and allow them to air dry. Calculate the TEER values.Aspirate the medium from the basolateral compartment and replace it with two milliliters of phenol red free endothelial cell growth medium in the triple cell culture blood-brain barrier model. Wash the cells in the apical compartment twice with HBSS. Add one milliliter of the FITC dextran solution in the apical compartment and cover the plate with aluminum foil, then place the plate in the incubator set at 37 degrees Celsius with 5%carbon dioxide for one hour.Take 100 microliters of medium from the basolateral compartments and transfer it into a black 96-well plate. Measure the fluorescence using a microplate reader with the excitation and the emission wavelengths set to 480 and 530 nanometers, respectively. Seed 200 microliters of HBMEC, primary astrocytes, and HBVP in the center of poly-D-lysine coated 35 millimeter glass bottom dishes at a density of 150, 000 cells per dish.Before seeding HBMEC, coat the bottom of the dishes with the attachment factor. Allow the cells to attach to the glass surface by leaving them overnight at 37 degree Celsius in a carbon dioxide incubator. Once confluence is reached, discard the culture medium and add two milliliters of pre-warmed glucose-free medium for oxygen-glucose deprivation or normal medium for controls.After oxygen-glucose deprivation treatment, replace the medium with the imaging optimized medium in all dishes, then perform fluorescence live-cell imaging with the GFP filter and top stage confocal microscope incubator as described in the text manuscript. The barrier integrity of the endothelial monolayer in the indicated blood-brain barrier model configurations was assessed by determining TEER before and after oxygen-glucose deprivations, as well as after 24 hours of re-oxygenation. For four hours the oxygen-glucose deprivation caused a significant decrease in TEER values only in HBMEC monoculture and the co-culture model with HBMEC and HBVP.These decreased levels reached the baseline levels following 24 hours of re-oxygenation. The TEER values in the triple co-culture model were significantly higher than those in the double co-culture controls or monoculture control immediately after oxygen-glucose deprivation. The paracellular permeability of endothelial monolayers to 20 kilodalton molecular mass, FITC dextran, was drastically increased in the HBMEC monoculture and to a lesser extent in the co-culture model with HBMEC and HBVP as compared to normoxic controls.Furthermore, 20 kilodalton FITC dextran permeability levels were the lowest in the triple brain-blood barrier model among all models under normoxic and oxygen-glucose deprivation conditions. No changes were observed in 70 kilodalton, FITC dextran flux across endothelial monolayers in any of the models. All primary human types exposed to oxygen-glucose deprivation exhibited strong green fluorescence, proving that the imaged live cells were hypoxic.After seeding human brain vascular pericytes on the abluminal side of well inserts, it is very important to cover them with the flip plate to prevent evaporation. In our model we use a relatively small, 0.4 micrometer pore diameter of polyester well inserts making it suitable for the screening of drug candidates to any disease that requires crossing the blood-brain barrier for treatment. This technique provides an excellent opportunity to visualize modification of proteins and transporters if needed.

a-triple-primary-cell-culture-model-human-blood-brain-barrier-for

Research

JoVE Journal

Biochemistry

Thermostabilization, Expression, Purification, and Crystallization of the Human Serotonin Transporter Bound to S-citalopram

The serotonin transporter is a sodium and chloride-coupled transporter that &#34;pumps&#34; extracellular serotonin into cells. S-citalopram is a drug used to treat depression and anxiety by binding to the serotonin transporter with high-affinity, blocking serotonin reuptake. Here we report an efficient procedure and a set of tools to stabilize, express, purify, and crystallize serotonin transporter-antibody complexes bound to S-citalopram and other antidepressants. Mutations which stabilize the serotonin transporter were identified using an S-citalopram binding assay. Serotonin transporter expressed in baculovirus-transduced HEK293S GnTI- cells, was reconstituted into proteoliposomes and used to raise high-affinity antibodies. We have developed a strategy to discover antibodies that are useful for structural studies. A straightforward approach for the expression of antibody fragments in Sf9 cells has also been established. Transporter-antibody complexes purified using this procedure are well-behaved and readily crystallize, producing complexes with S-citalopram that diffract X-rays to 3-4 &#197; resolution. The strategies developed here can be utilized to determine the structure of other challenging membrane proteins.

Thermostabilization, Expression, Purification, and Crystallization of the Human Serotonin Transporter Bound to S-citalopram

This manuscript describes how to screen for thermostabilizing mutations, purify the human serotonin transporter, generate high affinity antibodies, and crystallize the serotonin transporter-antibody complex bound to the antidepressant drug S-citalopram. This protocol can be adapted to the study of other challenging membrane transporters, receptors, and channels.

The serotonin transporter is a sodium and chloride-coupled transporter that &#34;pumps&#34; extracellular serotonin into cells. S-citalopram is a drug ...

Using Scaffold Liposomes to Reconstitute Lipid-proximal Protein-protein Interactions In Vitro

Studies of integral membrane proteins in vitro are frequently complicated by the presence of a hydrophobic transmembrane domain. Further complicating these studies, reincorporation of detergent-solubilized membrane proteins into liposomes is a stochastic process where protein topology is impossible to enforce. This paper offers an alternative method to these challenging techniques that utilizes a liposome-based scaffold. Protein solubility is enhanced by deletion of the transmembrane domain, and these amino acids are replaced with a tethering moiety, such as a His-tag. This tether interacts with an anchoring group (Ni2+ coordinated by nitrilotriacetic acid (NTA(Ni2+)) for His-tagged proteins), which enforces a uniform protein topology at the surface of the liposome. An example is presented wherein the interaction between Dynamin-related protein 1 (Drp1) with an integral membrane protein, Mitochondrial Fission Factor (Mff), was investigated using this scaffold liposome method. In this work, we have demonstrated the ability of Mff to efficiently recruit soluble Drp1 to the surface of liposomes, which stimulated its GTPase activity. Moreover, Drp1 was able to tubulate the Mff-decorated lipid template in the presence of specific lipids. This example demonstrates the effectiveness of scaffold liposomes using structural and functional assays and highlights the role of Mff in regulating Drp1 activity.

Using Scaffold Liposomes to Reconstitute Lipid-proximal Protein-protein Interactions In Vitro

This paper describes a method for assessing the interactions and assemblies of integral membrane proteins in vitro with various partner factors in a lipid-proximal environment.

Studies of integral membrane proteins in vitro are frequently complicated by the presence of a hydrophobic transmembrane domain. Further complicating ...

Time-resolved ElectroSpray Ionization Hydrogen-deuterium Exchange Mass Spectrometry for Studying Protein Structure and Dynamics

Intrinsically disordered proteins (IDPs) have long been a challenge to structural biologists due to their lack of stable secondary structure elements. Hydrogen-Deuterium Exchange (HDX) measured at rapid time scales is uniquely suited to detect structures and hydrogen bonding networks that are briefly populated, allowing for the characterization of transient conformers in native ensembles. Coupling of HDX to mass spectrometry offers several key advantages, including high sensitivity, low sample consumption and no restriction on protein size. This technique has advanced greatly in the last several decades, including the ability to monitor HDX labeling times on the millisecond time scale. In addition, by incorporating the HDX workflow onto a microfluidic platform housing an acidic protease microreactor, we are able to localize dynamic properties at the peptide level. In this study, Time-Resolved ElectroSpray Ionization Mass Spectrometry (TRESI-MS) coupled to HDX was used to provide a detailed picture of residual structure in the tau protein, as well as the conformational shifts induced upon hyperphosphorylation.

Conformational flexibility plays a critical role in protein function. Herein, we describe the use of time-resolved electrospray ionization mass spectrometry coupled to hydrogen-deuterium exchange for probing the rapid structural changes that drive function in ordered and disordered proteins.

Intrinsically disordered proteins (IDPs) have long been a challenge to structural biologists due to their lack of stable secondary structure elements. ...

A Colorimetric Method for Measuring Iron Content in Plants

Iron, one of the most important micronutrients in living organisms, is involved in basic processes, such as respiration and photosynthesis. Iron content is rather low in all organisms, amounting in plants to about 0.009% of dry weight. To date, one of the most accurate methods for measuring iron concentration in plant tissues is flame absorption atomic spectroscopy. However, this approach is time-consuming and expensive and requires specific equipment not commonly found in plant laboratories. Therefore, a simpler, yet accurate method that can be routinely used is needed. The colorimetric Prussian Blue method is regularly used for qualitative iron staining in animal and plant histological sections. In this study, we adapted the Prussian Blue method for quantitative measurements of iron in tobacco leaves. We validated the accuracy of this method using both atomic spectroscopy and Prussian Blue staining to measure iron content in the same samples and found a linear regression (R2 = 0.988) between the two procedures. We conclude that the Prussian Blue method for quantitative iron measurement in plant tissues is precise, simple, and inexpensive. However, the linear regression presented here may not be appropriate for other plant species, due to potential interactions between the sample and the reagent. Establishment of a regression curve is thus needed for different plant species.

We present a simple and reliable protocol for measuring iron content in plant tissues using the colorimetric Prussian Blue method.

Iron, one of the most important micronutrients in living organisms, is involved in basic processes, such as respiration and photosynthesis. Iron content ...

Assessing the Viability of a Synthetic Bacterial Consortium on the In Vitro Gut Host-microbe Interface

The interplay between host and microbiota has been long recognized and extensively described. The mouth is similar to other sections of the gastrointestinal tract, as resident microbiota occurs and prevents colonisation by exogenous bacteria. Indeed, more than 600 species of bacteria are found in the oral cavity, and a single individual may carry around 100 different at any time. Oral bacteria possess the ability to adhere to the various niches in the oral ecosystem, thus becoming integrated within the resident microbial communities, and favouring growth and survival. However, the flow of bacteria into the gut during swallowing has been proposed to disturb the balance of the gut microbiota. In fact, oral administration of P. gingivalis shifted bacterial composition in the ileal microflora. We used a synthetic community as a simplified representation of the natural oral ecosystem, to elucidate the survival and viability of oral bacteria subjected to simulated gastrointestinal transit conditions. Fourteen species were selected, subjected to in vitro salivary, gastric, and intestinal digestion processes, and presented to a multicompartment cell model containing Caco-2 and HT29-MTX cells to simulate the gut mucosal epithelium. This model served to unravel the impact of swallowed bacteria on cells involved in the enterohepatic circulation. Using synthetic communities allows for controllability and reproducibility. Thus, this methodology can be adapted to assess pathogen viability and subsequent inflammation-associated changes, colonization capacity of probiotic mixtures, and ultimately, potential bacterial impact on the presystemic circulation.

Assessing the Viability of a Synthetic Bacterial Consortium on the In Vitro Gut Host-microbe Interface

Gut host-microbe interactions were assessed using a novel approach combining a synthetic oral community, in vitro gastrointestinal digestion, and a model of the small intestine epithelium. We present a method that can be adapted to evaluate cell invasion of pathogens and multi-species biofilms, or even to test probiotic formulations&#39; survivability.

The interplay between host and microbiota has been long recognized and extensively described. The mouth is similar to other sections of the ...

Calibration-free In Vitro Quantification of Protein Homo-oligomerization Using Commercial Instrumentation and Free, Open Source Brightness Analysis Software

Number and brightness is a calibration-free fluorescence fluctuation spectroscopy (FFS) technique for detecting protein homo-oligomerization. It can be employed using a conventional confocal microscope equipped with digital detectors. A protocol for the use of the technique in vitro is shown by means of a use case where number and brightness can be seen to accurately quantify the oligomeric state of mVenus-labelled FKBP12F36V before and after the addition of the dimerizing drug AP20187. The importance of using the correct microscope acquisition parameters and the correct data preprocessing and analysis methods are discussed. In particular, the importance of the choice of photobleaching correction is stressed. This inexpensive method can be employed to study protein-protein interactions in many biological contexts.

Calibration-free In Vitro Quantification of Protein Homo-oligomerization Using Commercial Instrumentation and Free, Open Source Brightness Analysis Software

This protocol describes a calibration-free approach for quantifying protein homo-oligomerization in vitro based on fluorescence fluctuation spectroscopy using commercial light scanning microscopy. The correct acquisition settings and analysis methods are shown.

Number and brightness is a calibration-free fluorescence fluctuation spectroscopy (FFS) technique for detecting protein homo-oligomerization. It can be ...

Studying RNA Interactors of Protein Kinase RNA-Activated during the Mammalian Cell Cycle

Protein kinase RNA-activated (PKR) is a member of the innate immune response proteins and recognizes the double-stranded secondary structure of viral RNAs. When bound to viral double-stranded RNAs (dsRNAs), PKR undergoes dimerization and subsequent autophosphorylation. Phosphorylated PKR (pPKR) becomes active and induces phosphorylation of the alpha subunit of eukaryotic initiation factor 2 (eIF2&#945;) to suppress global translation. Increasing evidence suggests that PKR can be activated under physiological conditions such as during the cell cycle or under various stress conditions without infection. However, our understanding of the RNA activators of PKR is limited due to the lack of a standardized experimental method to capture and analyze PKR-interacting dsRNAs. Here, we present an experimental protocol to specifically enrich and analyze PKR bound RNAs during the cell cycle using HeLa cells. We utilize the efficient crosslinking activity of formaldehyde to fix PKR-RNA complexes and isolate them via immunoprecipitation. PKR co-immunoprecipitated RNAs can then be further processed to generate a high-throughput sequencing library. One major class of PKR-interacting cellular dsRNAs is mitochondrial RNAs (mtRNAs), which can exist as intermolecular dsRNAs through complementary interaction between the heavy-strand and the light-strand RNAs. To study the strandedness of these duplex mtRNAs, we also present a protocol for strand-specific qRT-PCR. Our protocol is optimized for the analysis of PKR-bound RNAs, but it can be easily modified to study cellular dsRNAs or RNA-interactors of other dsRNA binding proteins.

We present experimental approaches for studying RNA-interactors of double-stranded RNA binding protein kinase RNA-activated (PKR) during the mammalian cell cycle using HeLa cells. This method utilizes formaldehyde to crosslink RNA-PKR complexes and immunoprecipitation to enrich PKR-bound RNAs. These RNAs can be further analyzed through high-throughput sequencing or qRT-PCR.

Protein kinase RNA-activated (PKR) is a member of the innate immune response proteins and recognizes the double-stranded secondary structure of viral ...

A Strategy to Identify Compounds that Affect Cell Growth and Survival in Cultured Mammalian Cells at Low-to-Moderate Throughput

Cytotoxicity is a critical parameter that needs to be quantified when studying drugs that may have therapeutic benefits. Because of this, many drug screening assays utilize cytotoxicity as one of the critical characteristics to be profiled for individual compounds. Cells in culture are a useful model to assess cytotoxicity before proceeding to follow up on promising lead compounds in more costly and labor-intensive animal models. We describe a strategy to identify compounds that affect cell growth in a tdTomato expressing human neural stem cells (NSC) line. The strategy uses two complementary assays to assess cell number. One assay works via the reduction of 3-(4,5-dimethylthizol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) to formazan as a proxy for cell number and the other directly counts the tdTomato expressing NSCs. The two assays can be performed simultaneously in a single experiment and are not labor intensive, rapid, and inexpensive. The strategy described in this demonstration tested 57 compounds in an exploratory primary screen for toxicity in a 96-well plate format. Three of the hits were characterized further in a six-point dose response using the same assay set-up as the primary screen. In addition to providing excellent corroboration for toxicity, comparison of results from the two assays may be effective in identifying compounds affecting other aspects of cell growth.

It is often necessary to assess the potential cytotoxicity of a set of compounds on cultured cells. Here, we describe a strategy to reliably screen for toxic compounds in a 96-well format.

Cytotoxicity is a critical parameter that needs to be quantified when studying drugs that may have therapeutic benefits. Because of this, many drug ...

A Semi-Quantitative Drug Affinity Responsive Target Stability (DARTS) assay for studying Rapamycin/mTOR interaction

Drug Affinity Responsive Target Stability (DARTS) is a robust method for detection of novel small molecule protein targets. It can be used to verify known small molecule-protein interactions and to find potential protein targets for natural products. Compared with other methods, DARTS uses native, unmodified, small molecules and is simple and easy to operate. In this study, we further enhanced the data analysis capabilities of the DARTS experiment by monitoring the changes in protein stability and estimating the affinity of protein-ligand interactions. The protein-ligand interactions can be plotted into two curves: a proteolytic curve and a dose-dependence curve. We have used the mTOR-rapamycin interaction as an exemplary case for establishment of our protocol. From the proteolytic curve we saw that the proteolysis of mTOR by pronase was inhibited by the presence of rapamycin. The dose-dependency curve allowed us to estimate the binding affinity of rapamycin and mTOR. This method is likely to be a powerful and simple method for accurately identifying novel target proteins and for the optimization of drug target engagement.

A Semi-Quantitative Drug Affinity Responsive Target Stability DARTS assay for studying Rapamycin/mTOR interaction

In this study, we enhanced the data analysis capabilities of the DARTS experiment by monitoring the changes in protein stability and estimating the affinity of protein-ligand interactions. The interactions can be plotted into two curves: a proteolytic curve and a dose-dependence curve. We have used mTOR-rapamycin interaction as an exemplary case.

Drug Affinity Responsive Target Stability (DARTS) is a robust method for detection of novel small molecule protein targets. It can be used to verify known ...

Real-Time, Semi-Automated Fluorescent Measurement of the Airway Surface Liquid pH of Primary Human Airway Epithelial Cells

In recent years, the importance of mucosal surface pH in the airways has been highlighted by its ability to regulate airway surface liquid (ASL) hydration, mucus viscosity and activity of antimicrobial peptides, key parameters involved in innate defense of the lungs. This is of primary relevance in the field of chronic respiratory diseases such as cystic fibrosis (CF) where these parameters are dysregulated. While different groups have studied ASL pH both in vivo and in vitro, their methods report a relatively wide range of ASL pH values and even contradictory findings regarding any pH differences between non-CF and CF cells. Furthermore, their protocols do not always provide enough details in order to ensure reproducibility, most are low throughput and require expensive equipment or specialized knowledge to implement, making them difficult to establish in most labs. Here we describe a semi-automated fluorescent plate reader assay that enables the real-time measurement of ASL pH under thin film conditions that more closely resemble the in vivo situation. This technique allows for stable measurements for many hours from multiple airway cultures simultaneously and, importantly, dynamic changes in ASL pH in response to agonists and inhibitors can be monitored. To achieve this, the ASL of fully differentiated primary human airway epithelial cells (hAECs) are stained overnight with a pH-sensitive dye in order to allow for the reabsorption of the excess fluid to ensure thin film conditions. After fluorescence is monitored in the presence or absence of agonists, pH calibration is performed in situ to correct for volume and dye concentration. The method described provides the required controls to make stable and reproducible ASL pH measurements, which ultimately could be used as a drug discovery platform for personalized medicine, as well as adapted to other epithelial tissues and experimental conditions, such as inflammatory and/or host-pathogen models.

We present a protocol to make dynamic measurements of the airway surface liquid pH under thin film conditions using a plate-reader.