The authors would like to thank the researchers belonging to GRIVAS Health for their valuable input. Also, midwives and clinical staff from the Obstetrics and Gynecology Service belong to the Hospital de Chillan, Chile. Founded by Fondecyt Regular 1200250.

The research was carried out following the principles expressed in the Declaration of Helsinki and under the authorization of the respective Ethical Review Boards. All human participants gave their informed consent before sample collection, as reported previously25. Additionally, the Bioethics and Biosafety Committee of the B&#237;o-B&#237;o University approved this project (Fondecyt grant 1200250). The animal work was conducted in accordance with the cardinal principles of the three R&#39;s in th...

Evaluating Murine BBB Disruption Induced by Hypoxic Human Placenta-Derived sEVs

This study unveils fresh insights into potential harm resulting from sEVs isolated from placental explants cultured in hypoxic conditions on the disruption of the rodent blood-brain barrier. The pathological mechanism involves a reduction in CLND-5 in the posterior brain region25.
Prior investigations have revealed that plasma-sEVs from individuals with preeclampsia induce endothelial dysfunction in various organs using in vitro models46...

Approximately 70% of maternal deaths due to preeclampsia, a hypertensive pregnancy syndrome characterized by impaired placentation processes, maternal systemic endothelial dysfunction, and, in severe cases, multi-organ failure1,2, are associated with acute cerebrovascular complications3,4. Most maternal deaths occur in low and middle-income countries5. However, the underlying mechanisms are still unclear despite the clinical and epidemiological relevance of cerebrovascular complications associated with preeclampsia.
On the other hand, extracellular vesicles (EVs) (diameter ~30-400 nm) are essential mediators of intercellular communication among tissues and organs, including maternal-placental interaction6. In addition to proteins and lipids on the external surface, EVs carry cargo within (proteins, RNA, and lipids). EVs can be categorized into (1) exosomes (diameter ~50-150 nm, also named small EVs (sEVs)), (2) medium/large EVs, and (3) apoptotic bodies, which differ by size, biogenesis, content, and potential signaling function. The composition of EVs is determined by the cells from which they originate and the disease type7. Syncytiotrophoblast-derived EVs express placental alkaline phosphatase (PLAP)8,9, which detects placentae-derived circulating small EVs (PDsEVs) in pregnancy. Also, PLAP helps discern changes in the PDsEVs cargo and their effects in preeclampsia versus normotensive pregnancies10,11,12,13,14,15.
The placenta has been recognized as the necessary component in the pathophysiology of preeclampsia16 or cerebral complications associated with this disease17,18,19. However, how this distant organ might induce alterations in brain circulation is unknown. Since sEVs play pivotal roles in cell-to-cell communication due to their capacity to transfer bioactive components from donor to recipient cells6,20,21, a growing number of studies have associated placental sEVs with the generation of maternal endothelial dysfunction21,22,23,24, including brain endothelial cells25,26in women with preeclampsia. Thus, the compromise of brain endothelial function may lead to disruption of the blood-brain barrier (BBB), a critical component in cerebrovascular complications associated with preeclampsia3,27.
Nevertheless, preclinical findings using rat cerebral vessels exposed to serum of women with preeclampsia28 or human brain endothelial cells exposed to plasma of women with preeclampsia29 reported that circulating factor(s) induce disruption of the BBB. Despite several candidates with the potential to harm the BBB present in the maternal circulation during preeclampsia, such as elevated levels of proinflammatory cytokines (i.e., tumor necrosis factor)18,28 or vascular regulators (i.e., vascular endothelial growth factor (VEGF))29,30,31, or oxidative molecules such as oxidized-lipoproteins (oxo-LDL)32,33, among others34, none of them establishes a direct connection between the placenta and the BBB. Recently, sEVs isolated from hypoxic placentas have shown the capacity to disrupt the BBB in nonpregnant female mice25. Since placental sEVs may carry most of the listed circulating factors with the capacity to disrupt the BBB, sEVs are considered suitable candidates to connect the injured placenta, be the carrier of harmful circulating factors, and disrupt the BBB in preeclampsia.
This protocol allows us to investigate whether sEVs isolated from placental explants cultured under hypoxic conditions can disrupt the BBB in nonpregnant female mice as a proxy for understanding the pathophysiology of cerebral complications during preeclampsia.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Adult mice brain slecer matrice 3D printed</td>
			<td>Open access file</td>
			<td>Adult mice</td>
			<td>Adult mice brain slicer. Printed in PLA filament.</td>
		</tr>
		<tr>
			<td>Anti &#946;-Actin primary antibody</td>
			<td>Sigma-Aldrich</td>
			<td>Clon AC-74</td>
			<td>Antibody for loading control (Western blot)</td>
		</tr>
		<tr>
			<td>Anti-Claudin5 primary antibody</td>
			<td>Santa cruz Biotechnology</td>
			<td>sc-374221</td>
			<td>Primary antibody for tight junction protein CLDN5 of mice BBB (Western blot)</td>
		</tr>
		<tr>
			<td>BCA protein kit</td>
			<td>Thermo Scientific</td>
			<td>23225</td>
			<td>Kit for measuring protein concentration</td>
		</tr>
		<tr>
			<td>Culture media #200 500 mL</td>
			<td>Thermo Fisher Scientific</td>
			<td>m200500</td>
			<td>Culture media for placental explants</td>
		</tr>
		<tr>
			<td>D180 CO2 incubator</td>
			<td>RWD Life science</td>
			<td>D180</td>
			<td>Standard incubator to estabilize explants and culture sEVs-Nor</td>
		</tr>
		<tr>
			<td>Evans blue dye&#160; &#62; 75% 10 g</td>
			<td>Sigma-Aldrich</td>
			<td>E2129.10G</td>
			<td>Dye to analize blood brain barrier disruption IN VIVO</td>
		</tr>
		<tr>
			<td>Fetal bovine serum 500 mL</td>
			<td>Thermo Fisher Scientific</td>
			<td>16000044</td>
			<td>Additive growth factor for culture media 200</td>
		</tr>
		<tr>
			<td>Himac Ultracentrifuge CP100NX</td>
			<td>Himac eppendorf group</td>
			<td>5720410101</td>
			<td>Ultracentrifuge for condicioned media &#62; 1,20,000 x g</td>
		</tr>
		<tr>
			<td>ImageJ software</td>
			<td>NIH</td>
			<td></td>
			<td>https://imagej.nih.gov/ij/download.html</td>
		</tr>
		<tr>
			<td>Isoflurane x 100 mL</td>
			<td>USP Baxter</td>
			<td>212-094</td>
			<td>Volatile inhalated anaesthesia agent for mice</td>
		</tr>
		<tr>
			<td>Kit CellTiter 96 Non-radioactive&#160;</td>
			<td>Promega</td>
			<td>0000105232</td>
			<td>In vitro assay for placental explants viability</td>
		</tr>
		<tr>
			<td>Mouse IgG Secondary antibody</td>
			<td>Thermo Fisher Scientific</td>
			<td>MO 63103</td>
			<td>Secondary antibody for CLDN5 (western blot)</td>
		</tr>
		<tr>
			<td>NanoSight NS300</td>
			<td>Malvern Panalytical</td>
			<td>90278090</td>
			<td>Nanotracking analysis of particles from placental explants condicioned media</td>
		</tr>
		<tr>
			<td>Paraformaldehide E 97% solution 500 mL</td>
			<td>Thermo Fisher Scientific</td>
			<td>A11313.22</td>
			<td>Fixative solution for brain tissue slices and intracardial perfusion (once diluted)</td>
		</tr>
		<tr>
			<td>PBS 1 X pH 7.4 500 mL</td>
			<td>Thermo Fisher Scientific</td>
			<td>10010023</td>
			<td>Wash solution for placenta explants</td>
		</tr>
		<tr>
			<td>Peniciline-streptomicine 100x 20 mL</td>
			<td>Thermo Fisher Scientific</td>
			<td>10378016</td>
			<td>Antiobiotics for placental explants culture media</td>
		</tr>
		<tr>
			<td>ProOX C21 Cytocentric O2 and CO2 Subchamber Controller</td>
			<td>BioSpherix</td>
			<td>SCR_021131</td>
			<td>CO2 regulator to induce Hypoxia in sealed chamber for sEVs-Hyp</td>
		</tr>
		<tr>
			<td>Sodium Thiopental 1 g</td>
			<td>Chemie</td>
			<td>7061</td>
			<td>humanitarian euthanasia agent</td>
		</tr>
		<tr>
			<td>Somnosuite low flow anesthesia system</td>
			<td>Kent Scientifics</td>
			<td>SS-01</td>
			<td>Isoflurane vaporizer for small rodents</td>
		</tr>
		<tr>
			<td>Surgical Warming platform</td>
			<td>Kent Scientifics</td>
			<td>A41166</td>
			<td>Warming platform for mainteinance anesthesia in mice</td>
		</tr>
		<tr>
			<td>Syringe Filters, Polytetrafluoroethylene (PTFE), Hydrophobic, 0.22 &#181;m, Sterile, 25 mm</td>
			<td>Southern labware</td>
			<td>10026</td>
			<td>Filtration of condicioned media harvested from placental explants&#160;</td>
		</tr>
		<tr>
			<td>Tabletop High-Speed Micro Centrifuges&#160;HITACHI himac CT15E/CT15RE</td>
			<td>Hitachi medical systems</td>
			<td>6020</td>
			<td>Serial centrifugations of condicioned media &#60; 1,20, 000 x g</td>
		</tr>
		<tr>
			<td>Trinocular stereomicroscope transmided and reflective light 10x-160x&#160;</td>
			<td>Center Medical</td>
			<td>2597</td>
			<td>Stereomicroscope to register brain slices</td>
		</tr>
	</tbody>
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disruption of the mouse blood-brain barrier by small extracellular vesicles from hypoxic human placentas

Cerebrovascular complications, including cerebral edema and ischemic and hemorrhagic stroke, constitute the leading cause of maternal mortality associated with preeclampsia. The underlying mechanisms of these cerebrovascular complications remain unclear. However, they are linked to placental dysfunction and blood-brain barrier (BBB) disruption. Nevertheless, the connection between these two distant organs is still being determined. Increasing evidence suggests that the placenta releases signaling molecules, including extracellular vesicles, into maternal circulation. Extracellular vesicles are categorized according to their size, with small extracellular vesicles (sEVs smaller than 200 nm in diameter) considered critical signaling particles in both physiological and pathological conditions. In preeclampsia, there is an increased number of circulating sEVs in maternal circulation, the signaling function of which is not well understood. Placental sEVs released in preeclampsia or from normal pregnancy placentas exposed to hypoxia induce brain endothelial dysfunction and disruption of the BBB. In this protocol, we assess whether sEVs isolated from placental explants cultured under hypoxic conditions (modeling one aspect of preeclampsia) disrupt the BBB in vivo.

Author Spotlight: Modeling an Aspect of Preeclampsia in Female Mice Using Hypoxic Human Placenta-Derived Small Extracellular Vesicles

Disruption of the Mouse Blood-Brain Barrier by Small Extracellular Vesicles from Hypoxic Human Placentas

Our research is focused on the placenta/brain communication. We are exploring whether small extracellular vesicles can disrupt the blood-brain barrier, and if that is the potential underlying mechanism associated with cerebrovascular complication observed in women with preeclampsia. We have previously shown that plasma of women with preeclampsia can impair the blood-brain barrier.However, the nature of this potential harmful factor present in the plasma is unknown. Results from our laboratory show that extracellular vesicles derived from the plasma of women with preeclampsia, or from placentas, cultured in hypoxia, impairs the blood-brain barrier. The underlying mechanism of how placental extracellular vesicles impair the blood-brain barrier needs further investigation.That includes analysis of the content of extracellular vesicles, such as specific microRNAs that control the expression of digestion proteins in brain endothelial cells.

This protocol evaluates the capacity of sEVs derived from placentas cultured in hypoxia to disrupt the BBB in nonpregnant mice. This method allows one to understand better the potential connection between the placenta and the brain in normal and pathological conditions. In particular, this method may constitute a proxy to analyze placental sEVs participation in the onset of cerebral complications in preeclampsia.
Contrary to mice injected with sEVs-Nor, mice injected with sEVs-Hyp show a progr...

Watch this Scientific Journal Video about Author Spotlight: Modeling an Aspect of Preeclampsia in Female Mice Using Hypoxic Human Placenta-Derived Small Extracellular Vesicles at JoVE.com

A protocol is presented to evaluate whether small EVs (sEVs) isolated from placental explants cultured under hypoxic conditions (modeling one aspect of preeclampsia) disrupt the blood-brain barrier in nonpregnant adult female mice.

Cerebrovascular complications, including cerebral edema and ischemic and hemorrhagic stroke, constitute the leading cause of maternal mortality associated ...

Disruption of the Mouse Blood-Brain Barrier by Small Extracellular Vesicles from Hypoxic Human Placentas

Abstract