We have shown that pMSCs can transition macrophages from an inflammatory M1 into an anti-inflammatory M2 phenotype. Our findings suggest a new immunosuppressive property of pMSCs that may be employed in the resolution of inflammation associated with inflammatory diseases and in tissue repair.

Problem-Women with antiphospholipid antibodies (aPL) are at risk for recurrent miscarriage, preeclampsia and preterm labor. aPL target the placenta directly by binding to Beta 2 -Glycoprotein I (β 2 GPI) expressed on the surface of trophoblast cells. The objective of this study was to determine the effects of aPL on trophoblast function and the mechanisms involved.Method of study-First trimester trophoblast were treated with anti-β 2 GPI monoclonal antibodies and patient-derived aPL, after which cell survival and function was evaluated.Results-We report that anti-β 2 GPI antibodies trigger an inflammatory response in trophoblast, characterized by increased secretion of IL-8, MCP-1, GRO-α and IL-1β, and that this occurs in a TLR-4/MyD88-dependent manner. At high concentrations, these antibodies also induce caspasemediated cell death. This was attenuated upon disabling of the MyD88 pathway, suggesting that anti-β 2 GPI-induced inflammatory mediators compromise trophoblast survival by acting in an autocrine/ paracrine manner. Enhanced IL-8, GRO-α and IL-1β secretion also occured when trophoblast were incubated with antibodies from patients with antiphospholipid syndrome. Heparin, which acts as a pro-survival factor in human trophoblast, attenuated the anti-β 2 GPI antibody-mediated cell death, and also the pro-inflammatory response, but only at high concentrations.Conclusions-These findings demonstrate that aPL triggers a placental inflammatory response via the TLR-4/MyD88 pathway, which in turn compromises trophoblast survival. Thus, the TLR-4/ MyD88 pathway may provide a new therapeutic target to improve pregnancy outcome in antiphospholipid syndrome patients.

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In recent years, attention has turned to examining the biodistribution of EVs in recipient animals to bridge between knowledge of EV function in vitro and in vivo. We undertook a systematic review of the literature to summarize the biodistribution of EVs following administration into animals. There were time‐dependent changes in the biodistribution of small‐EVs which were most abundant in the liver. Detection peaked in the liver and kidney in the first hour after administration, while distribution to the lungs and spleen peaked between 2–12 h. Large‐EVs were most abundant in the lungs with localization peaking in the first hour following administration and decreased between 2–12 h. In contrast, large‐EV localization to the liver increased as the levels in the lungs decreased. There was moderate to low localization of large‐EVs to the kidneys while localization to the spleen was typically low. Regardless of the origin or size of the EVs or the recipient species into which the EVs were administered, the biodistribution of the EVs was largely to the liver, lungs, kidneys, and spleen. There was extreme variability in the methodology between studies and we recommend that guidelines should be developed to promote standardization where possible of future EV biodistribution studies.

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