Name: in vitro assays to assess blood-brain barrier mesh-like vessel formation and disruption
Uploaded: 2017-06-20T14:00:00
Description: Watch this Scientific Journal Video about In Vitro Assays to Assess Blood-brain Barrier Mesh-like Vessel Formation and Disruption at JoVE.com

Leon Tai is funded by University of Illinois Chicago start-up funds.

All experiments follow the University of Illinois, Chicago Institutional Animal Care and Use Committee protocols.
1. General Preparation
NOTE: The brain microvascular endothelial cell line (hCMEC/D3) is an extensively characterized immortalized human BEC line14,15,16,18,19. Culture the hCMEC/D3 cells on tis...

<ol>
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The methods described can be utilized to address several fundamental biological questions surrounding cerebrovascular coverage24. Specifically, they can identify which receptors and signaling pathways play a role in angiogenesis, vessel coverage in cancer tissue, and peripheral endothelial cells relevant to the brain. Examples include angiogenic growth factor receptors, nitric oxide, mitogen activated protein kinase signaling and calcium signaling25,<sup class="x...

The blood-brain barrier (BBB) of cerebral capillaries is the largest interface of blood-to-brain contact and plays a central role in the homeostasis of the central nervous system (CNS)1,2. Dynamic processes at the BBB prevent the uptake of unwanted molecules from the blood, remove waste products from the CNS, supply essential nutrients and signaling molecules to the CNS, and modulate neuroinflammation1,2,3,4,5. BBB damage is prevalent during aging and several neurodegenerative disorders including Alzheimer&#39;s disease (AD), multiple sclerosis and stroke1,2,3,4,5,6. Therefore, BBB dysfunction may play a key role in neurodegenerative disorders, including as a therapeutic target.
Maintaining vessel coverage is important for the homeostatic functions of the BBB. However, in vivo and in vitro data conflict on whether the processes involved in neurodegenerative disorders cause higher or lower BBB coverage6,7,8,9,10,11,12,13, particularly in AD. Therefore, there is a strong rationale for the development of in vitro models using relevant cell types to assess and more comprehensively understand the dynamics of BBB coverage. Cerebral capillaries are composed of astrocytes, pericytes and brain endothelial cells (BECs)3. All cell types contribute to the function of the BBB through structural support and via the secretion of effector molecules such as angiogenic growth factors, cytokines and chemokines that act in paracrine- and autocrine-like fashion. However, the major effector cells of the BBB are BECs3. In general, the cell culture techniques for assessing BBB function are permeability assays performed on cells grown on filter inserts, or assessing levels of key BEC proteins, both after the addition of stressors14,15,16. Although important, these assays do not focus on the cerebrovascular coverage.
Here, our previous methods17 are detailed to assess BEC coverage and meshwork-like structures using single cultures of immortalized human BECs, single cultures of primary mouse BECs, and a humanized triple culture model (BECs, astrocytes and pericytes) of the BBB. The goal was to demonstrate the detrimental effect of oA&#946;, which is considered an important contributor to AD progression, on BEC coverage. The protective effect of the epidermal growth factor (EGF) highlights the potential of the technique as a therapeutic screening tool. The technique has several broad applications for basic and applied research including: 1) delineating the role of specific pathways on angiogenesis and vessel coverage, 2) evaluating the effects of disease and aging-relevant factors on angiogenesis and vessel coverage, and 3) identifying pharmacological targets.

<table border="0" cellpadding="0" cellspacing="0" width="847">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:379px;">hCMEC/D3 cells</td>
			<td style="width:183px;">Milipore</td>
			<td style="width:119px;">SCC066</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:379px;">EBM-2 basal media&#160;</td>
			<td style="width:183px;">Lonza</td>
			<td>CC-3156</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:379px;">Collagen Type 1</td>
			<td style="width:183px;">ThermoFisher</td>
			<td style="width:119px;">A1064401&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:379px;">HBSS, calcium, magnesium, no phenol red</td>
			<td style="width:183px;">ThermoFisher</td>
			<td style="width:119px;">14025092</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:379px;">HBSS, no calcium, no magnesium, no phenol red</td>
			<td style="width:183px;">ThermoFisher</td>
			<td style="width:119px;">14175095</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:379px;">Trypsin-EDTA (0.25%)</td>
			<td style="width:183px;">ThermoFisher</td>
			<td style="width:119px;">25200056</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:379px;">Final concentrations of the SingleQuot growth factor supplements for EBM2 media</td>
			<td style="width:183px;">Lonza</td>
			<td>CC-4147</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">5% FBS</td>
			<td style="width:183px;">Lonza</td>
			<td>CC-4147</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">10% Ascorbic acid</td>
			<td style="width:183px;">Lonza</td>
			<td>CC-4147</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">10% Gentamycin sulphate</td>
			<td style="width:183px;">Lonza</td>
			<td>CC-4147</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">25% Hydrocortisone</td>
			<td style="width:183px;">Lonza</td>
			<td>CC-4147</td>
			<td></td>
		</tr>
		<tr height="78">
			<td height="78" style="height:78px;width:379px;">1/4 volume of the supplied growth factors: fibroblast growth factor, epidermal growth factor, insulin-like growth factor, vascular endothelial growth factor</td>
			<td style="width:183px;">Lonza</td>
			<td>CC-4147</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Puromycin hydrochloride</td>
			<td style="width:183px;">VWR</td>
			<td style="width:119px;">80503-312</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:379px;">MEM-HEPES&#160;</td>
			<td style="width:183px;">Thermo Scientific&#160;</td>
			<td style="width:119px;">12360-038</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:379px;">Papain cell dissociation system (papain and DNase1)</td>
			<td style="width:183px;">Worthington Biochemical</td>
			<td style="width:119px;">LK003150</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:379px;">Human pericytes</td>
			<td style="width:183px;">Sciencell</td>
			<td>1200</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:379px;">Pericyte basal media</td>
			<td style="width:183px;">Sciencell</td>
			<td>1201</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:379px;">Pericyte growth supplement</td>
			<td style="width:183px;">Sciencell</td>
			<td>1252</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:379px;">Human Astrocytes</td>
			<td style="width:183px;">Sciencell</td>
			<td>1800</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:379px;">Astrocyte media</td>
			<td style="width:183px;">Sciencell</td>
			<td>1801</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:379px;">Astrocyte growth supplement</td>
			<td style="width:183px;">Sciencell</td>
			<td>1852</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:379px;">Basement membrane (Matrigel Growth Factor Reduced)&#160;</td>
			<td style="width:183px;">Corning</td>
			<td style="width:119px;">356231</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:379px;">Angiogenesis m-plates (96-well)</td>
			<td style="width:183px;">ibidi</td>
			<td style="width:119px;">89646</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:379px;">Human Epidermal growth factor&#160;</td>
			<td style="width:183px;">Shenendoah Biotechnology</td>
			<td style="width:119px;">100-26</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">CellTracker green&#160;</td>
			<td style="width:183px;">ThermoFisher</td>
			<td>C7025</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">CellTracker orange</td>
			<td style="width:183px;">ThermoFisher</td>
			<td>C34551</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">CellTracker blue&#160;</td>
			<td style="width:183px;">ThermoFisher</td>
			<td>C2110</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:379px;">Poly-l-lysine</td>
			<td style="width:183px;">Sciencell</td>
			<td>0403</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:379px;">10% Neutral Buffered Formalin</td>
			<td style="width:183px;">Sigma-Aldrich</td>
			<td>HT5012-60ML</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:379px;">C57BL mice</td>
			<td style="width:183px;">Jackson Laboratory</td>
			<td style="width:119px;">na</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:379px;">PCR tube strips</td>
			<td style="width:183px;">GeneMate</td>
			<td style="width:119px;">T-3014-2</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:379px;">Zeiss stereo discover v.8 dissecting microscope</td>
			<td style="width:183px;">Zeiss</td>
			<td style="width:119px;">na</td>
			<td></td>
		</tr>
	</tbody>
</table>

in vitro assays to assess blood-brain barrier mesh-like vessel formation and disruption

Blood-brain barrier (BBB) coverage plays a central role in the homeostasis of the central nervous system (CNS). The BBB is dynamically maintained by astrocytes, pericytes and brain endothelial cells (BECs). Here, we detail methods to assess BBB coverage using single cultures of immortalized human BECs, single cultures of primary mouse BECs, and a humanized triple culture model (BECs, astrocytes and pericytes) of the BBB. To highlight the applicability of the assays to disease states, we describe the effect of oligomeric amyloid-&#946; (oA&#946;), which is an important contributor to Alzheimer&#39;s disease (AD) progression, on BBB coverage. Further, we utilize the epidermal growth factor (EGF) to illuminate the drug screening potential of the techniques. Our results show that single and triple cultured BECs form meshwork-like structures under basal conditions, and that oA&#946; disrupts this cell meshwork formation and degenerates the preformed mesh structures, but EGF blocks this disruption. Thus, the techniques described are important for dissecting fundamental and disease-relevant processes that modulate BBB coverage.

In single cultures, both the hCMEC/D3 cells (Figure 3A) and the primary mouse BECs (Figure 3B) form meshwork-like structures throughout the well. The structures are characterized by a meshwork of interlinked nodes (Figure 3). In all the paradigms described (Figure 1), the meshwork-like structures are similar after 24 h in the control groups, forming ~20 meshwork-like str...

Watch this Scientific Journal Video about In Vitro Assays to Assess Blood-brain Barrier Mesh-like Vessel Formation and Disruption at JoVE.com

In Vitro Assays to Assess Blood-brain Barrier Mesh-like Vessel Formation and Disruption

Maintaining blood-brain barrier coverage is key for the homeostasis of the central nervous system. This protocol describes in vitro techniques to delineate the fundamental and pathological processes that modulate blood-brain barrier coverage.

In Vitro Assays to Assess Blood-brain Barrier Mesh-like Vessel Formation and Disruption

Blood-brain barrier (BBB) coverage plays a central role in the homeostasis of the central nervous system (CNS). The BBB is dynamically maintained by ...

The goals of this assay are to dissect the role of disease-relevant processes in blood brain-barrier coverage disruption, identify the underlying mechanisms, and test potential treatments in vitro.This method can answer key basic and applied research questions in the blood-brain barrier and neuro-degeneration fields.For example, by addressing whether disease-relevant stresses disrupt preformed network structures and identifying the underlying pathways.Through further screening, treatments can be identified that prevent stress-induced blood-brain barrier disruption for future in vivo testing.The implications of this technique extend towards mechanistic understanding of and treatment for Alzheimer's disease, because of the importance of the homeostatic functions of the blood-brain barrier on cognition.Though this method can provide insight into the blood-brain barrier dysfunction in Alzheimer's disease, it can also be applied to other neurodegenerative disorders with blood-brain barrier dysfunction, such as stroke.Begin by passaging hCMEC/D3 immortal endothelial cells at a ratio of one to five by incubating the cell sheet with calcium and magnesium-free HBSS for three minutes.Then detach the cells using five milliliters of 0.25%trypsin EDTA for five minutes.Neutralize the trypsin by adding five milliliters of EBM-2 complete medium.Collect the cells, and centrifuge at 290 times g for five minutes at four degrees Celsius.Following centrifugation, discard the supernatant, and resuspend the pellet in EBM-2 complete medium.Then, replate the cells at a one to five ratio.To prepare endothelial cells from the mouse brain, remove the brain stems and cerebella from seven euthanized mice with forceps.Then, detach the meninges by carefully rolling the brains on gauss.Then, place the brain tissue into a petri dish containing minimal essential medium with HEPES, and use a sterile razor blade to mince the remaining brain tissue.Then transfer the minced brain tissue to a 15 milliliter conical tube.And centrifuge at 290 times g for five minutes at four degrees Celsius.After removing the supernatant, add papain and DNase solution, and incubate in a 37 degree Celsius water bath for one hour to digest the tissue.Following the incubation, triturate the homogenate using a 19-gauge needle, and then a 21-gauge needle.Once triturated, add one volume of 22%bovine serum albumin solution.Then centrifuge at 1, 360 times g for 10 minutes at four degrees Celsius.Resuspend the resulting pellet in one milliliter of EBM-2 complete, and then centrifuge at 290 times g for five minutes at four degrees Celsius.After the centrifugation, again use one milliliter of EBM-2 complete medium to resuspend the cells, and plate the cells at one milliliter per well in collagen-coated, six-well plates.24 hours later, replace the medium with EBM-2 complete medium containing four micrograms per milliliter of puromycin hydrochloride, and continue to culture the cells until they reach full confluence at one times 10 to the fifth cells per square centimeter.Lastly, 24 hours prior to the assay, incubate the fully confluent brain endothelial cells in EBM-2 basal medium.On the day of the assay, pipette 10 microliters of basement membrane matrix into each well of a 96-well plate, and allow to set for one hour at 37 degrees Celsius.Suspend the lyophilized green cell tracking dye in 10 microliters of DMSO to generate a 10-millimolar stock solution.Dilute this solution to 10-micromolar in EBM-2 basal medium.Remove the medium from the six-well plate containing brain endothelial cells, and replace with EBM-2 basal containing the green cell tracking dye.Incubate the cells for 20 to 30 minutes at 37 degrees Celsius.Following the incubation, remove the medium with cell tracking dye, wash the cell sheet, and attach the cells with trypsin.Neutralize the trypsin with EBM-2 containing 10%FBS, and transfer the cells to centrifuge tubes.Centrifuge at 240 time g for five minutes at four degrees Celsius.Following centrifugation, resuspend the cell pellets in one milliliter of EBM-2 basal medium, plate the labeled cells in multiple 96-well plates at 10, 000 cells per well, and return the cells to the incubator until oligomeric oa

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Research

JoVE Journal

Medicine

MRI-guided Disruption of the Blood-brain Barrier using Transcranial Focused Ultrasound in a Rat Model

Focused ultrasound (FUS) disruption of the blood-brain barrier (BBB) is an increasingly investigated technique for circumventing the BBB1-5. The BBB is a significant obstacle to pharmaceutical treatments of brain disorders as it limits the passage of molecules from the vasculature into the brain tissue to molecules less than approximately 500 Da in size6. FUS induced BBB disruption (BBBD) is temporary and reversible4 and has an advantage over chemical means of inducing BBBD by being highly localized. FUS induced BBBD provides a means for investigating the effects of a wide range of therapeutic agents on the brain, which would not otherwise be deliverable to the tissue in sufficient concentration. While a wide range of ultrasound parameters have proven successful at disrupting the BBB2,5,7, there are several critical steps in the experimental procedure to ensure successful disruption with accurate targeting. This protocol outlines how to achieve MRI-guided FUS induced BBBD in a rat model, with a focus on the critical animal preparation and microbubble handling steps of the experiment.

Microbubble-mediated focused ultrasound disruption of the blood-brain barrier (BBB) is a promising technique for non-invasive targeted drug delivery in the brain1-3. This protocol outlines the experimental procedure for MRI-guided transcranial BBB disruption in a rat model.

Focused ultrasound (FUS) disruption of the blood-brain barrier (BBB) is an increasingly investigated technique for circumventing the BBB1-5. The BBB is a ...

Rat Model of Blood-brain Barrier Disruption to Allow Targeted Neurovascular Therapeutics

Endothelial cells with tight junctions along with the basement membrane and astrocyte end feet surround cerebral blood vessels to form the blood-brain barrier1. The barrier selectively excludes molecules from crossing between the blood and the brain based upon their size and charge. This function can impede the delivery of therapeutics for neurological disorders. A number of chemotherapeutic drugs, for example, will not effectively cross the blood-brain barrier to reach tumor cells2. Thus, improving the delivery of drugs across the blood-brain barrier is an area of interest.
The most prevalent methods for enhancing the delivery of drugs to the brain are direct cerebral infusion and blood-brain barrier disruption3. Direct intracerebral infusion guarantees that therapies reach the brain; however, this method has a limited ability to disperse the drug4. Blood-brain barrier disruption (BBBD) allows drugs to flow directly from the circulatory system into the brain and thus more effectively reach dispersed tumor cells. Three methods of barrier disruption include osmotic barrier disruption, pharmacological barrier disruption, and focused ultrasound with microbubbles. Osmotic disruption, pioneered by Neuwelt, uses a hypertonic solution of 25% mannitol that dehydrates the cells of the blood-brain barrier causing them to shrink and disrupt their tight junctions. Barrier disruption can also be accomplished pharmacologically with vasoactive compounds such as histamine5 and bradykinin6. This method, however, is selective primarily for the brain-tumor barrier7. Additionally, RMP-7, an analog of the peptide bradykinin, was found to be inferior when compared head-to-head with osmotic BBBD with 25% mannitol8. Another method, focused ultrasound (FUS) in conjunction with microbubble ultrasound contrast agents, has also been shown to reversibly open the blood-brain barrier9. In comparison to FUS, though, 25% mannitol has a longer history of safety in human patients that makes it a proven tool for translational research10-12.
In order to accomplish BBBD, mannitol must be delivered at a high rate directly into the brain's arterial circulation. In humans, an endovascular catheter is guided to the brain where rapid, direct flow can be accomplished. This protocol models human BBBD as closely as possible. Following a cut-down to the bifurcation of the common carotid artery, a catheter is inserted retrograde into the ECA and used to deliver mannitol directly into the internal carotid artery (ICA) circulation. Propofol and N2O anesthesia are used for their ability to maximize the effectiveness of barrier disruption13. If executed properly, this procedure has the ability to safely, effectively, and reversibly open the blood-brain barrier and improve the delivery of drugs that do not ordinarily reach the brain 8,13,14.

Blood-brain barrier disruption aids the delivery of certain drugs to the brain. Mannitol delivered intra-arterially shrinks cells surrounding blood vessels in order to physically disrupt the barrier.

Endothelial cells with tight junctions along with the basement membrane and astrocyte end feet surround cerebral blood vessels to form the blood-brain ...

An in vivo Assay to Test Blood Vessel Permeability

This method is based on the intravenous injection of Evans Blue in mice as the test animal model. Evans blue is a dye that binds albumin. Under physiologic conditions the endothelium is impermeable to albumin, so Evans blue bound albumin remains restricted within blood vessels. In pathologic conditions that promote increased vascular permeability endothelial cells partially lose their close contacts and the endothelium becomes permeable to small proteins such as albumin. This condition allows for extravasation of Evans Blue in tissues. A healthy endothelium prevents extravasation of the dye in the neighboring vascularized tissues. Organs with increased permeability will show significantly increased blue coloration compared to organs with intact endothelium. The level of vascular permeability can be assessed by simple visualization or by quantitative measurement of the dye incorporated per milligram of tissue of control versus experimental animal/tissue. Two powerful aspects of this assay are its simplicity and quantitative characteristics. Evans Blue dye can be extracted from tissues by incubating a specific amount of tissue in formamide. Evans Blue absorbance maximum is at 620 nm and absorbance minimum is at 740 nm. By using a standard curve for Evans Blue, optical density measurements can be converted into milligram dye captured per milligram of tissue. Statistical analysis should be used to assess significant differences in vascular permeability.

An in vivo Assay to Test Blood Vessel Permeability

We are presenting an in vivo assay to test blood vessel permeability. This assay is based on intravenous injection of a dye and subsequent visualization of its diffusion into interstitial spaces.

This method is based on the intravenous injection of Evans Blue in mice as the test animal model. Evans blue is a dye that binds albumin. Under ...

Stretch in Brain Microvascular Endothelial Cells (cEND) as an In Vitro Traumatic Brain Injury Model of the Blood Brain Barrier

Due to the high mortality incident brought about by traumatic brain injury (TBI), methods that would enable one to better understand the underlying mechanisms involved in it are useful for treatment. There are both in vivo and in vitro methods available for this purpose. In vivo models can mimic actual head injury as it occurs during TBI. However, in vivo techniques may not be exploited for studies at the cell physiology level. Hence, in vitro methods are more advantageous for this purpose since they provide easier access to the cells and the extracellular environment for manipulation.
Our protocol presents an in vitro model of TBI using stretch injury in brain microvascular endothelial cells. It utilizes pressure applied to the cells cultured in flexible-bottomed wells. The pressure applied may easily be controlled and can produce injury that ranges from low to severe. The murine brain microvascular endothelial cells (cEND) generated in our laboratory is a well-suited model for the blood brain barrier (BBB) thus providing an advantage to other systems that employ a similar technique. In addition, due to the simplicity of the method, experimental set-ups are easily duplicated. Thus, this model can be used in studying the cellular and molecular mechanisms involved in TBI at the BBB.

Stretch in Brain Microvascular Endothelial Cells cEND as an In Vitro Traumatic Brain Injury Model of the Blood Brain Barrier

In vitro traumatic brain injury models are being developed to reproduce in vivo brain deformation. Stretch-induced injury has been employed for astrocytes, neurons, glial cells, aortic, and brain endothelial cells. However, our system uses a blood brain barrier (BBB) model that possesses properties constituting a legitimate model of the BBB to establish an in vitro&#160;TBI model.

Due to the high mortality incident brought about by traumatic brain injury (TBI), methods that would enable one to better understand the underlying ...

Setting-up an In Vitro Model of Rat Blood-brain Barrier (BBB): A Focus on BBB Impermeability and Receptor-mediated Transport

The blood brain barrier (BBB) specifically regulates molecular and cellular flux between the blood and the nervous tissue. Our aim was to develop and characterize a highly reproducible rat syngeneic in vitro model of the BBB using co-cultures of primary rat brain endothelial cells (RBEC) and astrocytes to study receptors involved in transcytosis across the endothelial cell monolayer. Astrocytes were isolated by mechanical dissection following trypsin digestion and were frozen for later co-culture. RBEC were isolated from 5-week-old rat cortices. The brains were cleaned of meninges and white matter, and mechanically dissociated following enzymatic digestion. Thereafter, the tissue homogenate was centrifuged in bovine serum albumin to separate vessel fragments from nervous tissue. The vessel fragments underwent a second enzymatic digestion to free endothelial cells from their extracellular matrix. The remaining contaminating cells such as pericytes were further eliminated by plating the microvessel fragments in puromycin-containing medium. They were then passaged onto filters for co-culture with astrocytes grown on the bottom of the wells. RBEC expressed high levels of tight junction (TJ) proteins such as occludin, claudin-5 and ZO-1 with a typical localization at the cell borders. The transendothelial electrical resistance (TEER) of brain endothelial monolayers, indicating the tightness of TJs reached 300 ohm&#183;cm2 on average. The endothelial permeability coefficients (Pe) for lucifer yellow (LY) was highly reproducible with an average of 0.26 &#177;&#160;0.11 x 10-3 cm/min. Brain endothelial cells organized in monolayers expressed the efflux transporter P-glycoprotein (P-gp), showed a polarized transport of rhodamine 123, a ligand for P-gp, and showed specific transport of transferrin-Cy3 and DiILDL across the endothelial cell monolayer. In conclusion, we provide a protocol for setting up an in vitro BBB model that is highly reproducible due to the quality assurance methods, and that is suitable for research on BBB transporters and receptors.

Setting-up an In Vitro Model of Rat Blood-brain Barrier BBB: A Focus on BBB Impermeability and Receptor-mediated Transport

The aim of the present study was to validate the reproducibility of an in vitro BBB model involving a rat syngeneic co-culture of endothelial cells and astrocytes. The endothelial cell monolayer presented high TEER and low LY permeability. Expression of specific TJ proteins, functional responses to inflammation and functionality of transporters and receptors were assessed.

The blood brain barrier (BBB) specifically regulates molecular and cellular flux between the blood and the nervous tissue. Our aim was to develop and ...

A Novel in vivo Gene Transfer Technique and in vitro Cell Based Assays for the Study of Bone Loss in Musculoskeletal Disorders

Differentiation and activation of osteoclasts play a key role in the development of musculoskeletal diseases as these cells are primarily involved in bone resorption. Osteoclasts can be generated in vitro from monocyte/macrophage precursor cells in the presence of certain cytokines, which promote survival and differentiation. Here, both in vivo and in vitro techniques are demonstrated, which allow scientists to study different cytokine contributions towards osteoclast differentiation, signaling, and activation. The minicircle DNA delivery gene transfer system provides an alternative method to establish an osteoporosis-related model is particularly useful to study the efficacy of various pharmacological inhibitors in vivo. Similarly, in vitro culturing protocols for producing osteoclasts from human precursor cells in the presence of specific cytokines enables scientists to study osteoclastogenesis in human cells for translational applications. Combined, these techniques have the potential to accelerate drug discovery efforts for osteoclast-specific targeted therapeutics, which may benefit millions of osteoporosis and arthritis patients worldwide.

A Novel in vivo Gene Transfer Technique and in vitro Cell Based Assays for the Study of Bone Loss in Musculoskeletal Disorders

Differentiation of precursor cells into osteoclasts is regulated by cytokines and growth factors. Here, a novel gene transfer technique for differentiation of osteoclasts in vivo and cell culture protocols for differentiating precursor cells into osteoclasts in vitro as a method to study the effects of cytokines on osteoclastogenesis are described.

Differentiation and activation of osteoclasts play a key role in the development of musculoskeletal diseases as these cells are primarily involved in bone ...

Oxygen-Glucose Deprivation and Reoxygenation as an In Vitro Ischemia-Reperfusion Injury Model for Studying Blood-Brain Barrier Dysfunction

Ischemia-Reperfusion (IR) injury is known to contribute significantly to the morbidity and mortality associated with ischemic strokes. Ischemic cerebrovascular accidents account for 80% of all strokes. A common cause of IR injury is the rapid inflow of fluids following an acute/chronic occlusion of blood, nutrients, oxygen to the tissue triggering the formation of free radicals.
Ischemic stroke is followed by blood-brain barrier (BBB) dysfunction and vasogenic brain edema. Structurally, tight junctions (TJs) between the endothelial cells play an important role in maintaining the integrity of the blood-brain barrier (BBB). IR injury is an early secondary injury leading to a non-specific, inflammatory response. Oxidative and metabolic stress following inflammation triggers secondary brain damage including BBB permeability and disruption of tight junction (TJ) integrity.
Our protocol presents an in vitro example of oxygen-glucose deprivation and reoxygenation (OGD-R) on rat brain endothelial cell TJ integrity and stress fiber formation. Currently, several experimental in vivo models are used to study the effects of IR injury; however they have several limitations, such as the technical challenges in performing surgeries, gene dependent molecular influences and difficulty in studying mechanistic relationships. However, in vitro models may aid in overcoming many of those limitations. The presented protocol can be used to study the various molecular mechanisms and mechanistic relationships to provide potential therapeutic strategies. However, the results of in vitro studies may differ from standard in vivo studies and should be interpreted with caution.

Oxygen-Glucose Deprivation and Reoxygenation as an In Vitro Ischemia-Reperfusion Injury Model for Studying Blood-Brain Barrier Dysfunction

Ischemia-Reperfusion (IR) injury is associated with a high rate of morbidity and mortality. The goal of the in vitro model of oxygen-glucose deprivation and reoxygenation (OGD-R) described here is to assess the effects of ischemia reperfusion injury on a variety of cells, particularly in blood-brain barrier (BBB) endothelial cells.

Ischemia-Reperfusion (IR) injury is known to contribute significantly to the morbidity and mortality associated with ischemic strokes. Ischemic ...

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

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

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

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

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

Improved Method for the Establishment of an In Vitro Blood-Brain Barrier Model Based on Porcine Brain Endothelial Cells

The aim of this protocol presents an optimized procedure for the purification and cultivation of pBECs and to establish in vitro blood-brain barrier (BBB) models based on pBECs in mono-culture (MC), MC with astrocyte-conditioned medium (ACM), and non-contact co-culture (NCC) with astrocytes of porcine or rat origin. pBECs were isolated and cultured from fragments of capillaries from the brain cortices of domestic pigs 5-6 months old. These fragments were purified by careful removal of meninges, isolation and homogenization of grey matter, filtration, enzymatic digestion, and centrifugation. To further eliminate contaminating cells, the capillary fragments were cultured with puromycin-containing medium. When 60-95% confluent, pBECs growing from the capillary fragments were passaged to permeable membrane filter inserts and established in the models. To increase barrier tightness and BBB characteristic phenotype of pBECs, the cells were treated with the following differentiation factors: membrane permeant 8-CPT-cAMP (here abbreviated cAMP), hydrocortisone, and a phosphodiesterase inhibitor, RO-20-1724 (RO). The procedure was carried out over a period of 9-11 days, and when establishing the NCC model, the astrocytes were cultured 2-8 weeks in advance. Adherence to the described procedures in the protocol has allowed the establishment of endothelial layers with highly restricted paracellular permeability, with the NCC model showing an average transendothelial electrical resistance (TEER) of 1249 &#177; 80 &#937; cm2, and paracellular permeability (Papp) for Lucifer Yellow of 0.90 10-6 &#177; 0.13 10-6 cm sec-1 (mean &#177; SEM, n=55). Further evaluation of this pBEC phenotype showed good expression of the tight junctional proteins claudin 5, ZO-1, occludin and adherens junction protein p120 catenin. The model presented can be used for a range of studies of the BBB in health and disease and, with the highly restrictive paracellular permeability, this model is suitable for studies of transport and intracellular trafficking.

Improved Method for the Establishment of an In Vitro Blood-Brain Barrier Model Based on Porcine Brain Endothelial Cells

The aim of the protocol is to present an optimized procedure for the establishment of an in vitro blood-brain barrier (BBB) model based on primary porcine brain endothelial cells (pBECs). The model shows high reproducibility, high tightness, and is suitable for studies of transport and intracellular trafficking in drug discovery.

The aim of this protocol presents an optimized procedure for the purification and cultivation of pBECs and to establish in vitro blood-brain barrier (BBB) ...

Micro-dissection of Enamel Organ from Mandibular Incisor of Rats Exposed to Environmental Toxicants

Enamel defects resulting from environmental conditions and ways of life are public health concerns because of their high prevalence. These defects result from altered activity of cells responsible for enamel synthesis named ameloblasts, which present in enamel organ. During amelogenesis, ameloblasts follow a specific and precise sequence of events of proliferation, differentiation, and death. A rat continually growing incisors is a suitable experimental model to study ameloblast activity and differentiation stages in physiological and pathological conditions. Here, we describe a reliable and consistent method to micro-dissect enamel organ of rats exposed to environmental toxicants. The micro-dissected dental epithelia contain secretion- and maturation-stage ameloblasts that may be used for qualitative experiments, such as immunohistochemistry assays and in situ hybridization, as well as for quantitative analyses such as RT-qPCR, RNA-seq, and Western blotting.

Understanding enamel formation and possible alterations requires the study of ameloblast activity. Here, we describe a reliable and consistent method to micro-dissect enamel organs containing secretion- and maturation-stage ameloblasts that may be used for further quantitative and qualitative experimental procedures.

Enamel defects resulting from environmental conditions and ways of life are public health concerns because of their high prevalence. These defects result ...