Publication Date:
2018-11-29
Description:
Background Thrombosis is a common complication of hereditary hemolytic anemia (HHA). Etiology of a hypercoagulable state in patients with HHA involves inflammation and splenectomy, although the etiology of the latter is insufficiently established. Because the concentration of circulating extracellular vesicles (EVs) has been reported to increase after splenectomy, and because in patients with sickle cell disease (SCD) circulating EVs are associated with coagulation, we analyzed the concentration of circulating EVs and their procoagulant activity in plasma from splenectomized and non-splenectomized patients with HHA. Methods This is a cross sectional, observational study in adult patients with HHA (SCD, other hemoglobin disorders, red cell enzyme disorders, red cell membrane disorders). Blood samples were collected with a 21-gauge butterfly needle and collected in 9 mL citrate phosphate dextrose adenine (CPDA) vacutainers, without use of a tourniquet. The tubes were mixed gently and the time between blood collection and centrifugation was maximum one hour. EVs in platelet-depleted plasma were labeled for Heat Shock Protein 70, CD14 (monocyte-derived EVs), CD61 (platelet EVs), CD62e (endothelial EVs), CD62p (P-selectin-exposing platelet EVs), CD71 (reticulocyte EVs), CD144 (endothelial EVs), CD235a (erythrocyte EVs) and lactadherin (phosphatidylserine (PS)-exposing EVs), and measured with a dedicated flow cytometer for EVs (A60-micro, Apogee Flow systems; lower limit of detection 170-180 nm single EVs). The coagulant activity of EVs was studied by a fibrin generation test, which measures the EV-dependent clotting time of plasma. The time to fibrin formation (1/2max) was measured using optical densitometry (λ = 405 nm) and an arbitrary cut off of V1/2max 25% difference between duplicates or from patients that used anticoagulant medication were excluded from analysis Results Ninety seven patients were included in the study. Baseline characteristics are shown in Table 1. FGT of 63 patients were included. Thirteen patients (21%) had a positive FGT. Patients with positive FGT had increased concentrations of circulating EVs (CD61, CD71, lactadherin: p=
Print ISSN:
0006-4971
Electronic ISSN:
1528-0020
Topics:
Biology
,
Medicine
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