Comparison of the platelet activation status of single-donor platelets obtained with two different cell separator technologies.

Background: The microparticle content (MP%) of apheresis platelets-a marker of platelet activation-is influenced by donor factors and by external stressors during collection and storage. This study assessed the impact of apheresis technology and other factors on the activation status (MP%) of single-donor apheresis platelets.

Study Design And Methods: Data from six US hospitals that screened platelets by measuring MP% through dynamic light scattering (ThromboLUX) were retrospectively analyzed.

Screening of red blood cells for extracellular vesicle content as a product quality indicator.

Background: The controversy around the quality and clinical impact of stored and differentially manufactured red cell concentrates (RCCs) from different donor groups is ongoing. Current studies are limited by the lack of quality measures suitable for routine screening of RCCs. As extracellular vesicles (EVs) are markers of cellular activation or degradation, this study investigated the utility of EV screening to characterize the effects of RBCs production methods and storage.

Routine Screening Method for Microparticles in Platelet Transfusions.

Platelet inventory management based on screening microparticle content in platelet concentrates is a new quality improvement initiative for hospital blood banks. Cells fragment off microparticles (MP) when they are stressed. Blood and blood components may contain cellular fragments from a variety of cells, most notably from activated platelets.

Microparticle detection to guide platelet management for the reduction of platelet refractoriness in children - A study proposal.

Microparticles have been shown to shed from a variety of viable cells as a consequence of inflammatory processes, activation or physical stress. Seventy to 90% of circulating microparticles are thought to be platelet-derived. The content of microparticles in blood collected from normal blood donors is highly variable and transfers into the final blood component.

Characterization of platelet concentrates using dynamic light scattering.

Background: Each year, millions of platelet transfusions save the lives of cancer patients and patients with bleeding complications. However, between 10 and 30% of all platelet transfusions are clinically ineffective as measured by corrected count increments, but no test is currently used to identify and avoid these transfusions. ThromboLUX(®) is the first platelet test intended to routinely characterize platelet concentrates prior to transfusion.

Novel test for microparticles in platelet-rich plasma and platelet concentrates using dynamic light scattering.

Background: The level and clinical importance of platelet (PLT)-derived microparticles (PMPs) in PLT-rich plasma (PRP) and PLT transfusions is largely unknown due to the lack of technology to routinely determine the number and size of PMP in PLT samples. Dynamic light scattering (DLS) is ideally suited to measure particles of submicron size but has previously been limited to the analysis of PLT-free samples.

Study Design And Methods: PMPs were enumerated in 81 PRP and 79 apheresis PLT concentrate (APC) samples from the same donors using ThromboLUX (LightIntegra Technology, Inc.

Long-term aspirin and clopidogrel response evaluated by light transmission aggregometry, VerifyNow, and thrombelastography in patients undergoing percutaneous coronary intervention.

Background: A reduced response to aspirin and clopidogrel predicts ischemic events, but reliable tests are needed to identify low responders. We compared 3 platelet-function tests during long-term dual treatment with aspirin and clopidogrel.

Methods: Patients who underwent a percutaneous coronary intervention and were receiving a combination of 325 mg/day aspirin and 75 mg/day clopidogrel were followed for 1 year.

Platelet quality measured with dynamic light scattering correlates with transfusion outcome in hematologic malignancies.

Background: A clinically meaningful test for platelet (PLT) quality could improve the transfusion management of patients. The aim of this pilot study was to determine whether a new measure of PLT quality and function based on dynamic light scattering (DLS) correlates with transfusion outcome.

Study Design And Methods: For a total of 160 transfusions, the pretransfusion, 1 hour posttransfusion, and 24-hour posttransfusion PLT counts were routinely measured in 49 patients (31 male, 18 female; age 46 +/- 15 years) with hematologic malignancies.

The ELAPSE (Evaluation of Long-Term Clopidogrel Antiplatelet and Systemic Anti-Inflammatory Effects) study.

Objectives: This study was designed to evaluate the effects of long-term clopidogrel and aspirin administration on platelet aggregation, activation, and inflammation.

Background: Clopidogrel resistance was described in 15% to 30% of patients with short-term therapy, but its antiplatelet effects with long-term therapy is unknown.

Methods: We performed a prospective study of patients undergoing coronary stenting who were on aspirin for > or =5 days but not previously on clopidogrel.

Effects of aspirin and clopidogrel in healthy men measured by platelet aggregation and PFA-100.

There are no generally accepted definitions for low-response (frequently called resistance) to the platelet inhibitors, aspirin and clopidogrel. Low-response may increase the risk of cardiovascular events in atherosclerotic patients. We aimed to define the normal drug responses in healthy men.

Quebec platelet disorder: features, pathogenesis and treatment.

Quebec platelet disorder (QPD) is a rare, autosomal-dominant, inherited bleeding disorder that is associated with unique abnormalities in fibrinolysis. Its hallmark features are delayed-onset bleeding following hemostatic challenges that responds to fibrinolytic inhibitor therapy and increased expression and storage of the fibrinolytic enzyme urokinase plasminogen activator in platelets, without increased plasma urokinase plasminogen activator or systemic fibrinolysis. The increased urokinase plasminogen activator in QPD platelets is only partially inhibited, and, as a result, there is intraplatelet generation of plasmin, and secondary degradation of many platelet alpha-granule proteins.

Past and future approaches to assess the quality of platelets for transfusion.

No automated test exists to routinely measure platelet quality. Currently, the short, 5-day shelf life of platelet concentrates is largely dictated by the risk associated with bacterial contamination and not by platelet quality. With the implementation of bacterial testing and pathogen inactivation, platelet quality will become the major determinant for the shelf life of platelet concentrates.

Diagnosing platelet delta-storage pool disease in children by flow cytometry.

Bleeding problems are symptomatic of platelet delta-storage pool diseases (SPDs) such as Hermansky-Pudlak syndrome. Although at present no cure is available for delta-SPD, early diagnosis is of great importance for prophylactic and supportive treatment. This study tested the usefulness of a flow cytometric assay for platelet serotonin in children.

Platelet serotonin levels support depression scores for women with postpartum depression.

Objective: It is very challenging to make an unbiased diagnosis of psychiatric illness. Platelets have long been proposed as easily obtainable, neurological models of serotonergic neurons. This study examined whether a new measurement for platelet serotonin could aid in the diagnosis of postpartum depression and support the results from questionnaires.

Portable dynamic light scattering instrument and method for the measurement of blood platelet suspensions.

No routine test exists to determine the quality of blood platelet transfusions although every year millions of patients require platelet transfusions to survive cancer chemotherapy, surgery or trauma. A new, portable dynamic light scattering instrument is described that is suitable for the measurement of turbid solutions of large particles under temperature-controlled conditions. The challenges of small sample size, short light path through the sample and accurate temperature control have been solved with a specially designed temperature-controlled sample holder for small diameter, disposable capillaries.

The influence of selective serotonin reuptake inhibitors on human platelet serotonin.

Clinical depression has been proposed to be an independent risk factor for cardiovascular disease. While it is suggested that selective serotonin reuptake inhibitors (SSRIs) reduce the risk of acute cardiovascular problems of depressed patients, the effect of SSRIs on platelets, the only blood cells committed to serotonin (5-HT) transport, remains largely unknown. The goal of this pilot study was to measure the 5-HT levels in platelets of untreated and SSRI-treated depressed patients and normal subjects and to determine whether the interaction of SSRIs with platelets can explain their possible cardiovascular benefit in patients with depression.

A novel immunocytochemical assay for the detection of serotonin in platelets.

A method for the rapid, inexpensive and easy detection of platelet serotonin (5-hydroxytryptamine, 5-HT) is not currently available. Consequently, many patients suffering from unresolved platelet-related bleeding disorders are not examined for a possible platelet 5-HT deficiency. The direct measurement of 5-HT concentration with high-performance liquid chromatography (HPLC) or serotonin enzyme-linked immunosorbent assay (ELISA) is costly and highly demanding.