Placental cell-derived exosomes increase in maternal circulation with gestational age

Objectives: Studies completed to date provide persuasive evidence that placental cell-derived exosomes (PdE) play a significant role in intercellular communication pathways that potentially contribute to development of materno-fetal vascular exchange. Furthermore, the release and composition of these microvesicles during pregnancy remain to be fully elucidated. Ours aim was to establish the gestational-age profile of PdE in maternal plasma. Methods: Plasma samples (n=20 per group) were obtained from non-pregnant (control) and pregnant women in the first (FT: 11-14 weeks), second (ST: 22-24 weeks) and third (TT: 32-36 weeks) trimester pregnancy from Davila Clinic (Santiago, Chile) with informed consent. Plasma was collected and exosomes were isolated by differential and buoyant density centrifugation. The expression of CD63 and placenta-specific marker, PLAP in exosomes was determined by Western Blot. The effect of 100 μg/ml exosomes isolated from FT, ST and TT on endothelial cell migration were established using a real-time, live-cell imaging system (Incucyte™). Finally, the exosomal proteins where identified by liquid-chromatography mass spectrometry (MS, Triple Tof 5600 AbSciex). Results: Plasma exosome concentration was increased in pregnant women compared to non-pregnant women and increased with gestational age (p < 0.05). PLAP/CD63 ratio also increased significantly (p < 0.05) during gestation. Exosmes isolated from FT, ST and TT increased endothelial cell migration (1.9 ± 0.1-fold, 1.6 ± 0.2-fold and 1.3 ± 0.1-fold, respectively) compared to the control. MS analysis identified 100 different proteins involved mainly in immunomodulatory process and cell-to-cell communication. Conclusions: These data establish that the release of bioactive, PdE into the maternal plasma increases throughout pregnancy and alter the phenotype of endothelial cell in vitro. While the role of PdE in regulating maternal and/or fetal vascular responses, in normal and pathological pregnancies remains to be elucidated, changes in their protein profile may be of clinical utility in the diagnosis of placental dysfunction.