Search

Coagulation disturbances are major contributors to COVID-19 pathogenicity, but limited data exist on the involvement of extracellular vesicles (EVs) and residual cells (RCs). Fifty hospitalized COVID-19 patients stratified by their D-dimer levels into high (>1.5 mg/L, n = 15) or low (≤1.5 mg/l, n = 35) and 10 healthy controls were assessed for medium-sized EVs (mEVs; 200-1000 nm) and large EVs/ RCs (1000-4000 nm) by high sensitivity flow cytometry. EVs were analyzed for CD61, CD235a, CD45, and CD31, commonly used to detect platelets, red blood cells, leukocytes or endothelial cells, respectively, whilst phosphatidyl serine EVs/RCs were detected by lactadherin-binding implicating procoagulant catalytic surface. Small EV detection (sEVs; 50-200 nm) and CD41a (platelet integrin) colocalization with general EV markers CD9, CD63, and CD81 were performed by single particle interferometric reflectance imaging sensor. Patients with increased D-dimer exhibited the highest number of RCs and sEVs irrespective of cell origin (p < .05). Platelet activation, reflected by increased CD61+ and lactadherin+ mEV and RC levels, associated with coagulation disturbances. Patients with low D-dimer could be discriminated from controls by tetraspanin signatures of the CD41a+ sEVs, suggesting the changes in the circulating platelet sEV subpopulations may offer added prognostic value during COVID progression. [ABSTRACT FROM AUTHOR]

Background: Non-refrigerated whole blood can be used for bleeding emergencies when cold-stored whole blood is unavailable. Storage time in room temperature is usually limited to 24 h although there is little evidence supporting this practice. We studied the quality of whole blood stored in room temperature for 5 days to investigate the effects of prolonged storage time., Study Design and Methods: Non-leukoreduced whole blood in CPDA-1 from 10 group O or A RhD positive male donors was stored in +22°C for 120 h. Samples were taken daily to assess blood cultures, blood count and metabolic parameters. Platelet function and blood coagulation were evaluated with multiple electrode aggregometry, viscoelastic tests (sonorheometry and rotational thromboelastometry), thrombin generation assay and measurements of individual clotting factors., Results: Blood cell counts remained stable during storage. Metabolic changes were similar to those previously reported in cold-stored blood products. Most coagulation factor levels, including FVIII, decreased during storage but remained within physiological range. Thrombin generation remained mostly intact during storage. In viscoelastic tests, clotting times prolonged, but clot strength remained stable. Platelet function in multiple electrode aggregometry impaired along with storage. No bacterial growth was detected in any sample., Conclusion: Whole blood stored in room temperature for 5 days seems bacteriologically safe and retains most of its metabolic and hemostatic function. These results suggest that whole blood stored in room temperature may be usable for longer than the currently recommended 24 h., (© 2025 AABB.)

Background: Extracellular vesicles (EVs) have procoagulative properties. As EVs are known to accumulate in stored blood products, we compared the EV content and coagulation capacity of leukoreduced cold-stored whole blood (CSWB) with current prehospital and in-hospital component therapies to understand the role of EVs in the haemostatic capacity of ageing CSWB., Materials and Methods: Blood was obtained from 12 O RhD-positive male donors. CSWB was compared with in-hospital component therapy of red blood cells (RBCs), OctaplasLG and buffy-coat platelets and prehospital component therapy of RBC and lyophilized plasma. Samples were drawn on Days 1 and 14 of CSWB and RBC cold storage. Blood count, haemolysis markers, rotational thromboelastometry, sonorheometry and thrombin generation were analysed. EVs were analysed using nanoparticle tracking analysis and cellular origin was determined using imaging flow cytometry., Results: There was a trend towards increased production of both platelet and RBC-derived EVs during CSWB storage. Particle count increased during storage, whereas thrombin generation slowed down and in viscoelastic assays, clotting times prolonged, clot formation became impaired, and stiffness of the resulting clot decreased., Conclusion: Both platelet and RBC-derived EVs increased in number in CSWB during storage. This did not appear to compensate for the in vitro decreasing haemostatic capacity of ageing CSWB, suggesting EVs produced during storage may not have active procoagulative effects, but rather reflect the ageing of blood cells., (© 2025 Finnish Red Cross Blood Service and The Author(s). Transfusion Medicine published by John Wiley & Sons Ltd on behalf of British Blood Transfusion Society.)

Convalescent plasma (CP) therapy for COVID-19 infection may have favorable safety but varying efficacy, with concerns about its procoagulant impact. We investigated whether administration of CP to hospitalized patients affects their coagulation profile. Fifty-four patients randomized in a double-blinded fashion received either placebo, low-titer CP (LCP) or high-titer CP (HCP). Donor blood samples were obtained at the time of the plasmapheresis, while recipient blood samples were collected before infusion, one day post-infusion and between two and six days after infusion. Routine laboratory follow-up, coagulation biomarkers, antiphospholipid antibodies, and thrombin generation (TG) were assessed. CP donors had normal blood cell counts and coagulation profiles, without differences between LCP and HCP donors at the baseline. All CP recipients were on low-molecular-weight heparin thromboprophylaxis at the time of the infusion. Despite randomization, the HCP group had lower baseline (p = 0.004) and Day 1 platelet counts (p = 0.019) than the LCP group. Von Willebrand antigen (VWF:Ag) levels clearly exceeded normal without differences at baseline. At Day 1, LCP recipients had higher VWF:Ag (mean ± SD 224 ± 15%) than HCP recipients (210 ± 8%) (p = 0.012). In all groups, overall 80% lupus anticoagulant was positive. Baseline TG variables were comparable, but again LCP recipients exhibited higher endogenous thrombin potential (ETP) (1313 ± 535 nM.min) (p = 0.038) and peak TG (184 ± 106 nM) (p = 0.037) than the HCP group (870 ± 425 nM.min and 86 ± 54 nM). Our findings show that LCP increases VWF:Ag levels and enhances TG despite the thromboprophylaxis. These results suggest that HCP induces less hypercoagulability than LCP, which may contribute to the variability in CP efficacy., Competing Interests: Declaration of Conflicting InterestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.