Platelets play a key role in the pathogenesis of atherothrombosis, and also perform the physiological hemostasis. The platelet function assays have values in the investigating patients with suspected platelet disorders and in studying the effects of anti-platelet drugs. There are increasing assays for investigating platelet function, including assessment of platelet adhesion, activation and aggregation, etc. However, all of these assays have certain limited sensitivity. It is necessary to develop a simple, sensitive assay that measures the activated platelet. This article reviewed advances of researches on platelet function assays, including assay for general function of platelet, assay of platelet adhesion function, platelet activation assay, platelet aggregation assay, platelet coagulation assay and application of flow cytometry in assessment of platelet functions, etc. and looked forward to research prospect in this field.
Blood Platelets ; physiology ; Humans ; Platelet Activation ; physiology ; Platelet Adhesiveness ; physiology ; Platelet Aggregation ; physiology ; Platelet Function Tests ; methods ; trends

OBJECTIVE: To study the effect of gradient shear stress on platelet aggregation by microfluidic chip Technology. METHODS: Microfluidic chip was used to simulate 80% fixed stenotic microchannel, and the hydrodynamic behavior of the stenotic microchannel model was analyzed by the finite element analysis module of sollidwork software. Microfluidic chip was used to analyze the adhesion and aggregation behavior of platelets in patients with different diseases, and flow cytometry was used to detect expression of the platelet activation marker CD62p. Aspirin, Tirofiban and protocatechuic acid were used to treat the blood, and the adhesion and aggregation of platelets were observed by fluorescence microscope. RESULTS: The gradient fluid shear rate produced by the stenosis model of microfluidic chip could induce platelet aggregation, and the degree of platelet adhesion and aggregation increased with the increase of shear rate within a certain range of shear rate. The effect of platelet aggregation in patients with arterial thrombotic diseases were significantly higher than normal group (P<0.05), and the effect of platelet aggregation in patients with myelodysplastic disease was lower than normal group (P<0.05). CONCLUSION The microfluidic chip analysis technology can accurately analyze and evaluate the platelet adhesion and aggregation effects of various thrombotic diseases unde the environment of the shear rate, and is helpful for auxiliary diagnosis of clinical thrombotic diseases.
Humans ; Microfluidics ; Platelet Adhesiveness ; Platelet Aggregation ; Blood Platelets/metabolism* ; Platelet Aggregation Inhibitors/pharmacology* ; Platelet Activation/physiology* ; Thrombosis

BACKGROUND: Resveratrol has been shown to inhibit platelet aggregation. However, the mechanism for this action of resveratrol remains to be clarified. The purpose of this study was to elucidate the Ca METHODS: Ca RESULTS: Thapsigargin-induced Ca CONCLUSIONS The results suggest that resveratrol inhibits thrombin-induced platelet aggregation through decreasing Ca
Antioxidants/administration & dosage* ; Calcium/physiology* ; Humans ; Platelet Aggregation/drug effects* ; Platelet Aggregation Inhibitors/pharmacology* ; Resveratrol/pharmacology* ; Signal Transduction/drug effects*

Platelet glycoprotein VI (GPVI) is a major receptor for collagen on the platelet surface. It mediates the initial platelet contact with collagen, generates intracellular signals, increases the affinity of integrin receptor, and causes platelet aggregation and thrombosis. Suppression of GPVI function can significantly inhibit collagen-induced platelet adhesion, aggregation and thrombosis, so GPVI has become a novel target for antiplatelet therapy. Within the last few years, major advances have been made in understanding platelet-collagen interactions. In this paper, the advances of study on GPVI, including composition of GPVI, functions of GPVI, factors related with functions of GPVI, GPVI and clinic were summarized.
Humans ; Platelet Adhesiveness ; physiology ; Platelet Aggregation ; physiology ; Platelet Glycoprotein GPIIb-IIIa Complex ; metabolism ; physiology ; Platelet Glycoprotein GPIb-IX Complex ; metabolism ; physiology ; Platelet Membrane Glycoproteins ; chemistry ; metabolism ; physiology ; Protein Binding ; physiology

OBJECTIVETo study the pathological and clinical characteristics of a patient with spontaneous platelet aggregation of his giant and morphologically abnormal platelets.

METHODSPlatelet size and structure were observed under light microscope and electron microscope. Platelet aggregation was measured turbidometrically. Platelet glycoproteins (GP) were analyzed using flow cytometry. PCR and DNA sequencing were performed to identify the gene abnormality.

RESULTSThe patient had spontaneous platelet aggregation of giant platelets with thickened plasma membrane and increased number of granules in various shapes. Aspirin and ticlopidine did not affect the spontaneous aggregation. The expression of GP I b, GP II b, GP III a and P-selectin in the platelet membrane were in normal range. Results of gene analyses for GP I balpha, GP I bbeta and GPIX were also normal.

CONCLUSIONBoth morphological and functional abnormalities of the platelets from the patient were clearly distinguishable from that of other hereditary giant platelet disorders. It would probably represent a novel platelet disorder which had not been reported to date.

Aspirin ; pharmacology ; Bernard-Soulier Syndrome ; metabolism ; pathology ; Blood Platelet Disorders ; metabolism ; pathology ; Cell Size ; physiology ; Child ; Cytoplasmic Granules ; pathology ; ultrastructure ; Female ; Humans ; Platelet Aggregation ; drug effects ; physiology ; Platelet Aggregation Inhibitors ; pharmacology ; Platelet Membrane Glycoproteins ; genetics ; metabolism ; Ticlopidine ; pharmacology

This study was aimed to investigate the aggregation of rehydrated-lyophilized platelets. The aggregation rate of fresh and rehydrated-lyophilized platelets were measured by using thrombin, ristocetin, ADP and collagen as inductors and APACT2 aggregameter; the effects of intra- and extra-cellular trehalose on maximum aggregation rate of rehydrated-lyophilized platelets were detected by using ADP as an inductor. The results showed that the aggregation rate of fresh platelets was all about 100%, while aggregation rate of rehydrated lyophilized platelets was (70.17 +/- 7.36)%, (15.3 +/- 2.81)%, (68.67 +/- 6.86)%, (64.67 +/- 11.6)% respectively, when the concentration of thrombin, ristocetin, ADP and collagen was 1 U/ml, 1.6 mg/ml, 20 micromol/L and 2 microg/ml. The maximum aggregation rates of rehydrated-lyophilized platelets in intra- and extra-cellular trehalose, extracellular trehalose and blank control groups were (66.0 +/- 4.69)%, (25.3 +/- 2.42)% and (11.5 +/- 1.87)% (P < 0.01), meanwhile there was significant difference of rehydrated-lyophilized platelet aggregation rate between intra- and extra-cellular trehalose and extracellular trehalose groups (P < 0.01). It is concluded that the concentrations of thrombin (1 U/ml), ristocetin (1.6 mg/ml), ADP (20 micromol/L) and collagen (2 microg/ml) are optimal for platelets aggregation tests, the internal and extracellular trehalose significantly enhance the aggregation of rehydrated-lyophilized platelets.
Blood Platelets ; cytology ; drug effects ; metabolism ; Blood Preservation ; methods ; Freeze Drying ; methods ; Humans ; Platelet Aggregation ; physiology

Microcirculatory dysfunction of local wounds and distant tissues after burns results in ischemia and hypoxia of tissues and organs, thus affecting the course and prognosis of burns. Platelet is an important component of blood, and the changes in its rheological behavior influence the blood flow in the microcirculation, as well as the microvascular structure and function. The abnormality of platelet rheological behavior plays an important role in the occurrence and development of microcirculatory dysfunction after burn. Changes in rheological behavior of platelets are due to changes in platelet morphology, adhesion, aggregation, shrinkage functions, and release reaction. Investigation of platelet rheological behavior and its regulation after burn may be of significant implication in the analysis of patient's condition and instruction for treatment. This article reviews the changes in platelet rheological behavior and its regulation after burn in the aspects of morphology, adhesion, aggregation, shrinkage functions, and release reaction.
Blood Platelets ; physiology ; Burns ; blood ; physiopathology ; Hemodynamics ; Humans ; Microcirculation ; Platelet Aggregation ; Rheology

The objective of this study was to explore the changes of aggregation function of apheresis platelets and soluble P-selectin (sP-selectin) during storage. 20 samples of apheresis platelets were collected, and the aggregation function were examined by function test and the level of sP-selectin every day in storage of 5 days. The results showed that the aggregation function of platelets declined obviously during storage, there were significant differences between the first-day group and any of the other groups (p < 0.01). The max platelet aggregation rate was < or = 3% in the fourth-day group; sP-selectin level in plasma increased with prolong of storage time; there were significant differences between the first-day group and any of the other groups (p < 0.05). In conclusion, platelets were activated continuously during storage, while its aggregation function declines significantly. The ability of platelet aggregation to response to ADP loses almost completely since the fourth day during platelet storage. It should be paid more attention to the damage of apheresis collected platelets during storage.
Adult ; Blood Platelets ; metabolism ; physiology ; Humans ; Male ; P-Selectin ; blood ; Platelet Aggregation ; Platelet Count ; Plateletpheresis ; methods ; Specimen Handling

To explore the influence of raising oxygen (dissolved oxygen) content on function of platelet concentrate, the platelet concentrate was prepared by a CS-3000 plus blood cell separator. Experiments were divided into 2 groups: test group and control group. After raising oxygen content in platelet plasma under sterile operation, the platelet samples of two groups were preserved in oscillator with horizontal oscillation at 22 +/- 2 degrees C. The platelet count, platelet aggregation rate, lactic acid content and CD62p expression level of platelet were detected on 0, 1, 2, 3, 4, 5 days of platelet preservation. The results showed that the platelet count and platelet aggregation rate decreased with prolongation of preserved time, while the lactic acid content and CD62p expression level of platelet increased gradually. Compared with control group, there were significant differences in aggregation rate of platelet preserved for 2-3 days, and in CD62p expression level of platelet preserved for 1-3 days, while significant difference was found in lactic acid content of platelet preserved for 1-3 days. It is concluded that raising content of oxygen in platelet plasma can provide more oxygen to compensate oxygen supply deficiency for platelet metabolism and improve the efficiency of platelet oxygenic metabolism and the quality of platelet during preservation.
Blood Platelets ; drug effects ; physiology ; Blood Preservation ; methods ; Humans ; Lactic Acid ; metabolism ; Oxygen ; pharmacology ; Platelet Aggregation ; drug effects ; Platelet Count ; Platelet Function Tests

The purpose of this study was to evaluate in vitro the effects of hydrocortisone and aminophylline on adenosine diphosphate (ADP)-induced platelet aggregation in horses. Blood samples from 30 healthy Thoroughbred horses were collected by via jugular venipuncture to assess platelet aggregation. Platelet-rich and platelet-poor plasma were prepared from all samples by centrifugation and divided into three different aliquots. In the first aliquot, platelet aggregation was measured after platelet activation with 1 microM and 0.5 microM ADP (Group A). In the other two aliquots, the effect of a 10 min preincubation with hydrocortisone (Group B) or aminophylline (Group C) on ADP-induced aggregation at final ADP concentrations of 1 microM and 0.5 microM was observed. Platelet aggregation, recorded by an aggregometer, was evaluated by measuring the maximum degree of platelet aggregation and the initial velocities of platelet aggregation were obtained. Our results demonstrated the inhibitory effect of hydrocortisone and the induction effect of aminophylline on equine platelet responses in vitro.
Adenosine Diphosphate/pharmacology ; Aminophylline/*pharmacology ; Animals ; Anti-Inflammatory Agents/*pharmacology ; Female ; Horses/*physiology ; Hydrocortisone/*pharmacology ; Male ; Platelet Aggregation/*drug effects