Microparticles: a link to increased thrombin generation.

Abstract

Circulating microparticles in human plasma may play a significant role in thrombogenesis because they carry the initiator of blood coagulation, tissue factor. Microparticles in blood are derived from diverse cell types, including erythrocytes, endothelial cells and platelets. Thrombin generation is an important part of the coagulation system and might be influenced by the presence of microparticles in the circulation. With this study, we determined the contribution of microparticles to increased thrombin generation in plasma samples received for thrombophilia workup and compare that with normal plasma. Microparticles were isolated from 50 plasma samples with increased thrombin generation and 20 plasma samples with normal thrombin generation, using filtration. Thrombin generation assay were performed by adding a low concentration of tissue factor-containing phospholipids and a fluorescence substrate for thrombin formation to plasma samples and measuring fluorescence at 1-min intervals over a period of 90 min on all samples (with and without the presence of microparticles). The peak thrombin, velocity-index and area under the curve were calculated. Microparticles contribute to the different parameters in samples with increased thrombin generation as follows: 50 ± 19% for peak thrombin, 58 ± 24% for velocity-index and 35 ± 13% for area under the curve. Microparticles did not contribute to thrombin generation in plasma samples with normal thrombin generation. Microparticles play a significant role in coagulation and contribute largely to increased thrombin generation in plasma; however, microparticles do not contribute to coagulation in the plasma of participants with normal thrombin generation.