Effect of MSC and MSC-derived extracellular vesicles on human blood coagulation

Mesenchymal stem cells (MSC) have emerged as potent therapeutic tool for a number of pathologies, including immune ones. However, unwelcome effects of MSC on the blood coagulation were revealed in some cases, which require more in-depth analysis. In this study, we explored the trombotic properties of human MSC from umbilical cord. We revealed strong procoagulant effects of umbilical cord MSC toward human and rat whole blood and platelets-free plasma using rotational thromboelastometry and thrombodynamics tests. The similar potentiation of clotting was demonstrated for MSC-derived extracellular vesicles (EV). In order to suggest approaches to avoid unwanted effects we studied the impact of heparin supplement on MSC/EV procoagulation properties. We found that therapeutic doses of unfractionated heparin injected in the patient's blood (administered in vivo) did not abrogate the procoagulant properties of MSC. Mass-spectrometry analysis of proteins of MSC and EV involved in coagulation-associated pathways was used to evaluate mechanisms of protrombotic effects.