Quantification of bulk lipid species in human platelets and their thrombin-induced release.

Lipids play a central role in platelet physiology. Changes in the lipidome have already been described for basal and activated platelets. However, quantitative lipidomic data of platelet activation, including the released complex lipids, are unavailable. Here we describe an easy-to-use protocol based on flow-injection mass spectrometry for the quantitative analysis of bulk lipid species in basal and activated human platelets and their lipid release after thrombin activation. We provide lipid species concentrations of 12 healthy human donors, including cholesteryl ester (CE), ceramide (Cer), free cholesterol (FC), hexosylceramide (HexCer), lysophosphatidylcholine (LPC), lysophosphatidylethanolamine (LPE), phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI), phosphatidylserine (PS), sphingomyelin (SM) and triglycerides (TG). The assay exhibited good technical repeatability (CVs < 5% for major lipid species in platelets). Except for CE and TG, the inter-donor variability of the majority of lipid species concentrations in platelets was < 30% CV. Balancing of concentrations revealed the generation of LPC and loss of TG. Changes in lipid species concentrations indicate phospholipase-mediated release of arachidonic acid mainly from PC, PI, and PE but not from PS. Thrombin induced lipid release was mainly composed of FC, PS, PC, LPC, CE, and TG. The similarity of the released lipidome with that of plasma implicates that lipid release may originate from the open-canalicular system (OCS). The repository of lipid species concentrations determined with this standardized platelet release assay contribute to elucidating the physiological role of platelet lipids and provide a basis for investigating the platelet lipidome in patients with hemorrhagic or thrombotic disorders.

[Coagulation disorders in the intensive care unit - what is new?]. / Gerinnungsstörungen bei Intensivpatienten: Diagnostik und Therapie.

The phase III non-vitamin K dependent oral anticoagulants (NOAC) studies and recently published real world data on the use of dabigatran and rivaroxaban have shown that the bleeding profile in particular of intracranial and other life-threatening bleeding of NOAC is more favourable than that of warfarin. In case of a bleeding complication in a patient treated with a NOAC the recently updated EHRA practical guide offers management strategies. Idarucizumab, the specific antidot for dabigatran is approved to reverse the anticoagulant effect of dabigatran-treated patients who have serious bleeding and require an urgent procedure. Andexanet alfa, a specific antidot for direct and indirect factor Xa-inhibitors will be available in the future. The frequency of thrombocytopenia in ICU patients is high whereas the heparin induced thrombocytopenia (HIT) only counts for a small minority of patients with thrombocytopenia. To avoid an overdiagnosis of HIT a reliable and complete clinical and laboratory workup has to be performed. New immunoassays have been developed to provide results within a short period of time. These tests appear to have improved diagnostic accuracy compared with ELISAs in patients with suspected HIT and may reduce misdiagnosis and overtreatment. Acquired haemophilia (AH) is a rare and often life threatening bleeding disorder caused by autoantibodies against factor VIII. Susoctocog alfa is a B-domain deleted recombinant factor VIII porcine sequence that has recently been approved to treat severe bleeding in patients with AH. Susoctocog alfa offers the ability to effectively titrate and monitor dosing based on factor VIII activity levels.