To investigate stress levels, serum cortisol levels, and changes in IL-12 concentration in patients with missed abortion. Patients with missed abortion (n = 48) were age and gestational age-matched with normal early pregnancy cases (n = 48). All subjects completed a stress evaluation survey questionnaire about common stressors. Venous blood samples were collected at 07.00 hours, and serum cortisol and IL-12 concentrations were measured by electrochemiluminescence immunoassay and ELISA methods, respectively. Missed abortion patients demonstrated a significantly higher number of common stressors and higher serum cortisol levels compared to controls (both p < 0.05). Dilation and curettage did not lead to significant differences in serum cortisol and IL-12 levels (p > 0.05). Stress and immunity alterations of the immune system may contribute to the aetiology of missed abortion.

Placental dysfunction, including senescent changes, is associated with the pathogenesis of missed miscarriage, although the underlying mechanism is unclear. Increasing evidence indicates that placenta-specific miRNAs are packaged in extracellular vesicles (EVs) from placental syncytiotrophoblasts and are released into the maternal circulation. Aberrant cargos including miRNAs in placental EVs have been reported to be associated with the pathogenesis of complicated pregnancies. In this study, we compared the miRNA profiles in EVs derived from missed miscarriage and healthy placentae and investigated possible biological pathways which may be involved in senescence, one cause of missed miscarriage. The total concentration of RNA in placental EVs was not different between the two groups. However, there were 54 and 94 differentially expressed miRNAs in placental large and small EVs from missed miscarriage compared to EVs from healthy controls. The aberrantly expressed miRNAs seen in placental EVs were also observed in missed miscarriage placentae. Gene enrichment analysis showed that some of those differentially expressed miRNAs are involved in cellular senescence, endocytosis, cell cycle and endocrine resistance. Furthermore, transfection of trophoblasts by a single senescence-associated miRNA that was differentially expressed in placental EVs derived from missed miscarriage did not cause trophoblast dysfunction. In contrast, EVs derived from missed miscarriage placenta induced senescent changes in the healthy placenta. Our data suggested that a complex of placental EVs, rather than a few differentially expressed miRNAs in placental EVs derived from missed miscarriage placentae could contribute in an autocrine manner to placental senescence, one of the causes of missed miscarriage.

Human pregnancy is a highly orchestrated process requiring extensive cross-talk between the mother and the fetus. Extracellular vesicles released by the fetal tissue, particularly the placenta, are recognized as important mediators of this process. More recently, the importance of placental extracellular vesicle biodistribution studies in animal models has received increasing attention as identifying the organs to which extracellular vesicles are targeted to helps us understand more about this communication system. Placental extracellular vesicles are categorized based on their size into macro-, large-, and small-extracellular vesicles, and their biodistribution is dependent on the extracellular vesicle’s particle size, the direction of blood flow, the recirculation of blood, as well as the retention capacity in organs. Macro-extracellular vesicles are exclusively localized to the lungs, while large- and small-extracellular vesicles show high levels of distribution to the lungs and liver, while there is inconsistency in the reporting of distribution to the spleen and kidneys. This inconsistency may be due to the differences in the methodologies employed between studies and their limitations. Future studies should incorporate analysis of placental extracellular vesicle biodistribution at the macroscopic level on whole animals and organs/tissues, as well as the microscopic cellular level.

Extracellular vesicles (EVs) are lipid-bound vesicles released from cells that play a crucial role in many physiological processes and pathological mechanisms. As such, there is great interest in their biodistribution. One currently accessible technology to study their fate in vivo involves fluorescent labelling of exogenous EVs followed by whole-animal imaging. Although this is not a new technology, its translation from studying the fate of whole cells to subcellular EVs requires adaptation of the labelling techniques, excess dye removal and a refined experimental design. In this Review, we detail the methods and considerations for using fluorescence in vivo and ex vivo imaging to study the biodistribution of exogenous EVs and their roles in physiology and disease biology.

Mesenchymal stromal cells (MSC) have recently been explored for their potential use as therapeutics in veterinary medicine applications. Alternatively, MSC-derived extracellular vesicles (EVs) may also provide therapeutic benefits but as an off-the-shelf solution, provided they can be produced in large enough quantities and without the risk of contamination from bovine EVs contained in fetal bovine serum that is a common component of cell culture media. Towards this aim, we demonstrated the successful isolation and characterisation of equine MSCs from pre-implantation embryos. We also demonstrate that many of these lines can be propagated long-term in culture and conducted a head-to-head comparison of two bioreactor systems for scalable EV production including in serum-free conditions. Based on our findings, the CELLineTM AD 1000 flasks enabled higher cell density cultures and significantly more EV production than the FibercellTM system or conventional culture flasks. These findings will enable future isolation of equine MSCs and the scalable culture of their EVs for a wide range of applications in this rapidly growing field.