Abstract 810: Endothelial Microparticles: A Novel Marker For Endothelial Dysfunction In Patients with Diabetes Mellitus.
Background: Endothelial microparticles (EMPs) are membrane vesicles that are shed from endothelial cells (EC) in response to injury. On their surface are various signaling molecules that participate in atherosclerosis, thrombosis, and inflammation. Subsequently, the phenotypic assessment of EMPs can provide useful information reflecting the nature of EC injury. Considering that Diabetes Mellitus (DM) is a condition characterized by elevated inflammatory cytokines and EC dysfunction we tested the hypothesis that EMPs are elevated in patients with DM.
Methods and Results: Flow cytometry was used to measure EMPs identified by E-selectin (62E) and platelet-endothelial cell adhesion molecule 1 (CD31) in 20 patients with advanced DM. A cohort of 20 healthy individuals served as controls. Simultaneous detection of two antigens allowed us to distinguish EMPs from platelet (CD41a+) microparticles. The absolute number of EMPs was enumerated from platelet-free plasma using a technique with TruCount beads as an internal reference. EMPs are defined as elements ranging in size between 0.5 and 2 μm as assessed by the logarithmic amplification of their forward and side scatter signals. In addition, EMP morphology was examined by transmission electron microscopy. The pellet fraction of platelet-free plasma demonstrated multiple vesicles of diameter 0.5 – 2.0 μm. As assessed by flow cytometry, the absolute number of EMPs (EMPx104/mL) specific for CD31 was significantly increased in the DM population (CD31+ 41a−: 2.8 ± 0.98 to 7.8 ± 2.1 , p<0.05). Levels of CD62E+ 41a− specific EMPs were similar in DM and control groups.
Conclusion: We developed a single-platform flow cytometry method for quantitating the absolute number of EMPs in plasma from patients with DM. Although the specific relationship between plasma levels of EMPs and EC dysfunction is unclear, our study strengthens the link between DM and EMP production. Elevated levels of CD31+ EMPs might provide new options for risk assessment and may have implications for future treatment strategies of DM. Further investigation of the mechanisms involved in the release of EMPs in DM is warranted.