Clinical Research Directory

PLATELET Function Assay With Flow Imaging on ImageSTREAM Cytometer

Platelets are essential blood elements to maintain hemostasis. Quantitative or qualitative defects can be responsible of hemorrhagic (platelet disorders) or thrombotic (heparin induced thrombocytopenia \[HIT\]) troubles. Diagnosis of these pathologies is sometimes urgent and consists in delicate platelet functional assays that are mostly made in expert centers. These platelets functional assays measure platelets activation and/or aggregation in response to diverse inductors and may lack sensitivity. The investigators would like to propose a new diagnostic tool with the use of imaging flow cytometry which provides much more information than classic cytometer on cell morphology thanks to images collected by the optical channel of the ImageStream cytometer. The use of this cytometer offers an innovative approach. This study is a monocentric prospective and non-interventional study. The investigators will analyze patient samples with the ImageStream cytometer and reference laboratory tests (light transmission aggregometry and serotonin release assay) in parallel and compare results from the different techniques. This new diagnostic technique will demonstrate a non-inferiority diagnosis compared to reference tests and maybe a better sensibility.

Change in Platelet Lipid Metabolism and Procoagulant Phenotype Induced by Cardiopulmonary Bypass. Impact on Postoperative Inflammatory Response and Bleeding Complications During Cardiac Surgery.

The PLACARD research project aims to investigate the impact of CPB-induced platelet modifications during cardiac surgery on the post-operative inflammatory response and bleeding complications. Our objectives are to study the impact of CPB on the formation of procoagulant platelets, to assess changes in platelet lipid profile and bioenergetics before, during and after cardiac surgery, and to connect the ex-vivo observations to post-operative clinical and biological parameters of these patients during their stay in cardiovascular intensive care unit.

Coagulation Factors Alterations in Patients Undergoing Complex Thoraco-abdominal Aortic Aneurysm Repair

This study will evaluate the impact of complex thoraco-abdominal aortic aneurysm repair in coagulation during the immediate postoperative period in patients undergoing omplex thoraco-abdominal aortic aneurysm repair.

Inflammation, Platelets and Sickle Cell Disease

Sickle cell disease (SCD) is an autosomal recessive genetic disorder linked to a single mutation on beta-globin chains. This leads to red blood cell deformation and chronic hemolysis which can result in vaso-occlusive events, anemia and vasculopathy. Pathophysiology is incompletely understood, and beyond red blood cell's abnormalities this involves hemostasis and innate immunity. The aim of our study is to describe the mechanisms of thrombo-inflammation during the vaso-occlusive crisis (VOC) in adults with sickle cell disease.

Characterization and Quantification of Platelet/Leukocyte Aggregates in Patients With Suspected Heparin-induced Thrombocytopenia

The investigators would like to analyze platelet/leukoplak activation, quantify and morphologically characterize these aggregates using in vitro analysis, directly on whole blood from adult patients with suspected HIT. This would enable to better describe the in vivo pathophysiology of the HIT-suspect patient, and eliminate the need for platelet donors to perform the usual confirmatory techniques, whose inter- and intra-individual variability is very high. What's more, the SRA test, evaluated as the reference test, requires the use of radioisotopes and is therefore only carried out in a few biological expertise centers, resulting in a very long delay in the delivery of results. It should also be noted that, in practice, HÉPARINE is immediately stopped in patients with suspected HIT, and they are put on an expensive anticoagulant (DANAPAROIDE SODIQUE or ARGATROBAN) in curative doses until the results of the confirmatory tests are back. In this serious, life-threatening condition, it is essential to have a sensitive, specific test to confirm HIT as quickly as possible. Each patient with suspected HIT (rapid \>30% reduction in platelet count after initiation of heparin therapy) should have 4 tubes of 3.2% citrated whole blood (2.7ml) collected at the time of suspected HIT (D0) and before any therapeutic switch (or 24 h max after switch). A new sample (4 citrated tubes) will be taken at D4, D7 and D14 during hospitalization, in patients who test positive for anti-PF4/H Ac. All patients with suspected HIT will follow the standard diagnostic pathway, i.e. a screening test (immunological test for anti-PF4/heparin antibodies, total Ig, ACL TOP, Werfen) followed by a confirmatory test (platelet aggregation on TA-8V, STAGO and/or SRA). Doppler ultrasonography of the lower limbs will be performed in HIT-suspect patients with a positive anti-PF4/H antibody test, as currently performed as part of routine care.