Stress, Pregnancy, and Extracellular Vesicles: A Direct Line of Communication

How mother-fetus crosstalk across the placenta is critical for pregnancy and development.

Here’s something you maybe wouldn’t expect: maternal stress signals, encoded in tiny extracellular vesicles (EVs), cross the maternal-fetal divide. These EVs are packed with stress-induced cargo and can influence the fetus and they have the power to potentially alter its development. In a recent study, researchers not only uncovered this fascinating mechanism but also identifying EV origins using our anti-excitatory amino acid transporter 2 (EAAT2) antibody.(1)

Stress Turns EVs Into Messengers

When pregnant rats were exposed to stress, their circulating small EVs (sEVs) carried distinct stress signatures. Proteins associated with neurons, such as Aldolase C, significantly decreased, while proteins associated with astrocytes, including EAAT2, markedly increased, indicating stress-specific changes in cargo composition (Figure 1). Using Alomone Labs’ Anti-EAAT2 (GLT-1) (extracellular) Antibody (#AGC-022) – a key marker for astrocytic origin – the researchers pinpointed the source of these vesicles. This is an important finding because the shift toward astrocytic EV content under stress provides a mechanistic link between maternal stress and changes in the EV cargo. The increased astrocytic content could reflect a neuroprotective or compensatory mechanism, as astrocytes are known to respond to stress-related signaling.

Figure 1. Repetitive restraint stress induces changes in concentration and cargo of maternal circulating sEVs. (A) Size and concentration distribution profile of circulating blood plasma-borne sEVs from control and stressed pregnant dams. (B) Concentration (particles/ml) of blood plasma-borne sEVs in control and stressed pregnant dams. (C) Size (mode) of blood plasma-borne sEVs in control and stressed pregnant dams. Bars represent mean ± SEM (Control group: n = 9; Stress group: n = 13). (D) Representative images of Western blot analyses for characterization of blood plasma-borne sEVs from control (C) and stressed (S) pregnant dams. Positive (CD-63, flotillin-1, TSG-101) and negative (GM130) markers for sEVS were used for characterization. Rat brain protein homogenates were used as positive controls (+). (E-E’) Western blot analyses of maternal blood plasma-borne sEVs for brain neuronal-enriched (synaptophysin, GluN2A, Glun2B) and astrocyte-enriched (EAAT2, GFAP, Aldolase C) proteins. Representative images of Western blots (E) and densitometric quantification analyses (E’) are shown. Bars represent mean ± SEM (Control and Stress groups: n = 3 pools of plasma-borne sEVs; each pool is composed by plasma-derived sEVS from 4 different pregnant rats). * p < 0.05; ** p < 0.01 (Student’s t-test).

Maternal EVs Target the Fetus

Here’s where it gets really interesting. When sEVs from stressed mothers were fluorescently labeled and injected into other pregnant rats, they homed in on placental and fetal tissues, particularly in stress-like conditions (Figure 2). The effect wasn’t uniform – instead, fetal tissues took up these EVs differently depending on sex, with male tissues showing heightened receptivity. This implies that EVs don’t just passively transport stress signals – they ensure those signals are received and potentially acted upon.

Figure 2. Repetitive restraint stress affect biodistribution of maternal circulating sEVS into placental and fetal tissues. (A) Schematic representation of the experimental design. Plasma-borne sEVs from 4 control rats or 4 stressed rats at GD17.5 were isolated, pooled, and stained with the lipophilic marker DiR. Labelled-sEVS from both stressed and control rats (Donors) were intravenously (tail vein) injected into pregnant stressed and pregnant control recipient rats at E17.5 and analyzed after 24 h (at 18.5). (B, D) Representative images of DiR fluorescent signal distribution in placentas (B) and fetuses (D) 24 h after labelled-sEVs injection. PBS-DiR was used as negative control. (C, E) Quantification of DiR fluorescent signals in placentas (C) and fetuses (E) from Group CC (control recipients that received control donor sEVs), Group SS (stressed recipients that received donor sEVs from stressed pregnant dams), Group CS (control recipients that received donor sEvs from stressed dams), and Group SC (stressed recipients that received control donor sEVs). Fluorescence intensity (arbitrary units, A.U.) was normalized by placental and fetal area, respectively. Data shown as scatter dot plots with mean ± SEM. n = 44 placentas/fetuses from 4 litters for Group CC; n = 36 placentas/fetuses from 3 litters for Group SS; n = 50 placentas/fetuses from 4 litters for Group CS; n = 62 placentas/fetuses from 4 litters for Group SC. * p < 0.05 (Statistical comparisons by mixed-effects modelling to control for litter effects; treatments were used as fixed effect and litter as random effect).

A Diagnostic Window

The study proposes EVs as biomarkers for maternal stress – something that would offer a non-invasive way to monitor pregnancy health. The use of Alomone’s EAAT2 antibody also highlights a practical approach to identify EV origins. Beyond biomarkers, this research suggests therapeutic possibilities, where EV manipulation could mitigate the effects of stress on fetal development.

The data here takes EVs from their classic role as molecular couriers and makes adds biological diplomats to their jobs, translating maternal stress into fetal outcomes.

Reference

1. The study proposes EVs as biomarkers for maternal stress – something that would offer a non-invasive way to monitor pregnancy health. The use of Alomone’s EAAT2 antibody also highlights a practical approach to identify EV origins. Beyond biomarkers, this research suggests therapeutic possibilities, where EV manipulation could mitigate the effects of stress on fetal development.

   The data here takes EVs from their classic role as molecular couriers and makes adds biological diplomats to their jobs, translating maternal stress into fetal outcomes.