Study of the Thrombogenic Activity of Platelet-derived Microparticles from Patients with Acute Coronary Syndrome.

Background: To observe the thrombogenic activity of platelet-derived microparticles (PMPs) in PMP-free plasma from non-coronary artery disease (non-CAD) patients and explore the relationship between PMPs and thrombosis in acute coronary syndrome (ACS) patients.

Methods: Patients with ACS who were diagnosed at the outpatient department of cardiology in the People's Hospital of Xinjiang Uygur Autonomous Region, and non-CAD subjects were enrolled in the study from January 2011 to December 2014. Subjects were assigned to the ACS group (n=200) (which consisted of patients with acute myocardial infarction (AMI, n=100) and patients with unstable angina pectoris) (UAP, n=100), or to the non-CAD group (n=100). After informed consent was obtained from subjects, peripheral blood was collected from ACS patients and non-CAD subjects and then put into sodium citrate anticoagulant tubes. The PMPs were analyzed by flow cytometry using flow cytometry. The plasma of non-CAD patients was thawed and centrifuged to obtain MP-free plasma. MP-free plasma was placed into a black 96-well microplate at 40 μl per well. 10 μl PMP suspension containing 1×10, 1×10 or 1×10 PMPs from ACS patients or non-CAD patients was added into the MP-free plasma. The coagulation reaction was induced by adding 50 μl of fluorescence-labeled thrombin substrate, and the microplate was placed into the microplate reader.

Results: Compared with the PMP levels in the non-CAD patient group (40×10), the PMPs were increased in the AMI sub-group (250×10) and the UAP sub-group (126×10) of the ACS patients, and the differences were statistically significant (<0.05). The relative fluorescence intensity of the ACS group was higher than that of the non-CAD group at every time point, and the differences were of statistical significance (<0.05). The peak thrombogenic activity of 1×10, 1×10, 1×10 PMPs in ACS patients was at 6 min, 8 min, and 11 min respectively, whereas the thrombogenic activity of 1×10, 1×10, 1×10 PMPs in non-CAD patients was at 16 min, 21 min, and 41 min respectively.

Conclusion: The levels of platelets and PMPs in ACS patients were higher than those in non-CAD patients, implying that rupture of the coronary atherosclerotic plaques led to an increase in platelets and the subsequent massive release of PMPs by the activated platelets. The plaques in the ACS patients are prone to rupture such that the platelets are in an activated state and release a large amount of PMPs, therefore promoting thrombosis.