Clinical significance of circulating microparticles in Ph- myeloproliferative neoplasms.

Microparticles (MPs) are small membrane vesicles that are classified into subcategories based on their origin, such as platelet-derived MPs (PMPs), endothelial MPs (EMPs), red blood cell MPs (RMPs) and tissue factor MPs (TF + MPs). Philadelphia chromosome-negative myeloproliferative neoplasms (Ph-MPN) are disorders characterized by abnormal haematopoiesis, thrombosis and the JAK2V617F mutation. MPs are biomarkers for procoagulant state in cancer patients, but their relevance in patients with Ph-MPN was unclear. The present study aimed to measure MP variation in MPN patients and evaluate association with the JAK2V617F mutation and with thrombosis and splenomegaly. In total, 92 patients with MPN were enrolled in the present study, including 60 with essential thrombocythaemia (ET), 20 with polycythaemia vera (PV), and 12 with primary myelofibrosis (PMF). RMPs, PMPs, TF + MPs and EMPs were measured by flow cytometry. The levels of RMPs, PMPs, EMPs and TF + MPs in patients with Ph-MPN were all found to be significantly increased compared with controls (P<0.05). Additionally, the levels of all four types of MPs in the PMF group were significantly increased compared with the PV group (P<0.05), and the level of RMPs in the PMF group was significantly increased compared with the ET group (P<0.05). MP levels were increased in the Ph-MPN patients with thrombosis compared with patients without thrombosis (P<0.05). MP levels were increased in Ph-MPN patients with splenomegaly compared with patients without splenomegaly (P<0.05). The level of PMPs in patients with the JAK2V617F mutation was increased compared with patients without the mutation (P<0.05). In conclusion, the present study showed that MPs are associated with Ph-MPN pathogenesis, and may promote thrombosis.