Endothelial microparticle levels are similar in acute ischemic stroke and stroke mimics due to activation and not apoptosis/necrosis

Background: Endothelial microparticles (EMPs) are <2-mu m membranous blebs from endothelial cell membranes that have been demonstrated to be elevated in vasculopathic conditions. One study has demonstrated elevated EMPs in acute ischemic stroke (AIS) versus age- and comorbidity-matched controls. Objectives: To determine the level of EMPs in stroke mimics and AIS and determine if EMPs are released as a result of activation or apoptosis/necrosis in AIS. Methods: EMP levels in plasma of patients with AIS and stroke mimic patients were quantified by flow cytometry. Stroke status was verified in all patients by magnetic resonance imaging. Patients were matched for age and comorbidities. Markers for apoptosis/necrosis (platelet/endothelial cell adhesion molecule-1 [PECAM-1]/CD31 antigen) and activation (E-selectin/CD62e antigen) were compared. A PECAM-1/E-selectin ratio of >4.0 was used to determine whether EMPs were generated via activation or apoptosis/necrosis. Data were compared between groups using the Mann-Whitney U test. Results: EMP levels were similar in stroke mimic patients when compared with AIS; there was no difference between groups (PECAM-1, p = 0.393; E-selectin, p = 0.579). The PECAM-1/E-selectin ratio was also similar for AIS and stroke mimics, and all were >4.0. Conclusions: EMP levels were similar in patients with AIS and stroke mimic patients. The PECAM-1/E-selectin ratio demonstrated that EMPs were generated via activation and not apoptosis/necrosis. This suggests that EMPs may not be a good marker for AIS, given the inability to discriminate between stroke mimics and AIS. ACADEMIC EMERGENCY MEDICINE 2007; 14:685-690 (c) 2007 by the Society for Academic Emergency Medicine.