Vascular injury leads to formation of a structured thrombus as a consequence of platelet activation and aggregation, thrombin and fibrin formation, and trapping of leukocytes and red cells. This review summarises current evidence for heterogeneity of platelet responses and functions in the thrombus-forming process. Environmental factors contribute to response heterogeneity, as the platelets in ...

To assess the individual contributions of the platelet glycoprotein (GP) IIb/IIIa receptor and the alpha v beta 3 vitronectin receptor to platelet levels of fibrinogen and vitronectin, we analyzed the platelets from two groups of Glanzmann thrombasthenic patients: Iraqi-Jews, whose platelets lack both receptors, and Arab patients in Israel, whose platelets lack GPIIb/IIIa, but have normal or in...

The effect of human platelets with deficient lipoxygenase activities on leukotriene B4 (LTB4) synthesis by neutrophils was studied. When arachidonic acid (AA) metabolites obtained from the incubation of washed normal neutrophils and platelets with N-formylmethionylleucylphenylalanine (FMLP), cytochalasin B, and AA were analyzed by reversed-phase high-performance liquid chromatography, the synth...

To evaluate the poststorage viability of apheresis platelets stored for up to 18 days in 80% platelet additive solution (PAS)/20% plasma, 117 healthy subjects donated platelets using the Haemonetics MCS+, COBE Spectra (Spectra), or Trima Accel (Trima) systems. Control platelets from the same subjects were compared with their stored test PAS platelets by radiolabeling their stored and control pl...

To study the immunosuppressive effects of three different treatments, 30 dogs received at weekly intervals eight platelet transfusions from a single random donor dog. The three experimental protocols were daily oral cyclosporine (Cs) treatment of recipients; in vitro ultraviolet (UV)-irradiation of donor platelets; and Cs-loading of donor platelets. All nine recipients of Cs, 11/12 (92%) recipi...

Megakaryocytes and functional platelets were generated in vitro from murine embryonic stem (ES) cells using a coculture system with stromal cells. Morphologically two distinctive megakaryocytes were observed sequentially. Small megakaryocytes rapidly produced proplatelets on day 8 of the differentiation and large hyperploid megakaryocytes developed after day 12, suggesting primitive and definit...

Studies have indicated that platelets play an important role in tumorigenesis, and an abundance of platelets accumulate in the ovarian tumor microenvironment outside the vasculature. However, whether cancer cells recruit platelets within intestinal tumors and how they signal adherent platelets to enter intestinal tumor tissues remain unknown. Here, we unexpectedly found that large numbers of pl...

Platelets, derived from megakaryocytes, are anucleate cytoplasmic discs that circulate in the blood stream and play major roles in hemostasis, inflammation, and vascular biology. Platelet transfusions are used in a variety of medical settings to prevent life-threatening thrombocytopenia because of cancer therapy, other causes of acquired or inherited thrombocytopenia, and trauma. Currently, pla...

Platelets are small, oval, circulating, anucleate cells that upon endothelial damage form a haemostatic plug and stop blood leakage. Circulating platelets derive from bone-marrow-resident megakaryocytes that daily produce and release approximately 100 billions of new platelets into the blood stream (Kaushansky, 2006; Semple et al., 2011). During haemostasis, tethering platelets adhere to the va...

Continuous or repeated injury of rabbit aortae by indwelling vascular catheters caused the deposition of platelets on the injured vessels and the formation of thrombi rich in platelets and fibrin at sites where flow was most disturbed and injury was most extensive. Incorporation of 51Cr platelets into the thrombi reached a maximum between 3 and 24 hr. The platelet-fibrin-rich thrombi remained r...