DETECTION OF PLATELET-DERIVED MICROPARTICLES USING FLOW CYTOMETRY AND ITS CLINICAL APPLICATION

Objective.To establish a flow cytometric internal standard method for counting platelet-derived microparti-cles(PMPs)and to study its clinical significance. Methods. PMPs suspension(platelet poor plasma,PPP) was extracted by gradual centrifugation. According to the size of PMPs,3 μm and 0.8μm latex beads were used as internal standards for the quantitation. PMPs were counted by adjusting flow cytometric discrimination and voltage of forward scatter and side scatter. Results. In 30 healthy donors,the average concentration of resting PMPs was(1.2×105±5.7×104 )/ml and that of activated PMPs was(1.6×106±9.1×105)/ml. Compared with healthy donors,PMPs mean value was significantly higher(P< 0.001)in 18 patients with coronary artery disease,12 with acute cerebral infraction and 23 with chronic renal failure[the average PMPs concentration,( 6.1×105±2.5×105 )/ml, ( 6.8×105±3.4×105)/ml and(5.9×105±3.1×105)/ml respectively]. However,no significant difference in PMPs concentration was observed in 25 patients with acute leukemia and severe thrombocytopenia during the aplastic phase after chemotherapy [1.3×105±6.1×104)/ml,(P >0.05)] .Conclusions. PMPs is a useful indicator in monitoring platelet activation,and plays an important role in thrombotic disease. By flow cytometric internal standard method,PMPs can be counted rapidly and accurately,which may be very helpful in interlaboratory comparative studies.

Bionic immunoactivator copresenting autophagy promoting and costimulatory molecules for synergistic cancer immunotherapy

Immunotherapy has great promise in improving malignant tumor treatment.However,the efficacy of existing strategies is often limited by the immunosuppressive environment.Here,we demonstrate an in situ bionic immunoactivator,PLT-Bec1/DTA-1,with possessed natural advantages of platelets for tumor recruitment and activation,on which DTA-1(CD357 monoclonal antibody)and Bec1 were tethered as combined immune boosters.PLT-Bec1/DTA-1,as a self-triggered release repository,can deliver the pre-tethered Bec1 and DTA-1 deeply through the secretion of platelet microparticles(PMPs),thereby cooperate tacitly and exhibit superiority in immune activation of dendritic cells(DCs)and T cells via autophagy inducibility,coupled with glucocorticoid-induced tumor necrosis factor receptor(GITR)-triggered T_(Reg) suppression,remodeled the immunosuppressive network of tumor microenvironment.PLT-Bec1/DTA-1 promoted antigen presentation and T cell proliferation,and alleviated the low activity state of bone marrow-derived dendritic cells(BMDCs)in tumor suppressive environment.PLT-Bec1/DTA-1 inhibited tumor recurrence(5-and 13-fold lower of control group in tumor volume)and CD8^(+)T/T_(Reg) ratio(6.3-and 8.8-fold vs.control group)in mouse tumor model after intravenous or subcutaneous administration.Also,PLT-Bec1/DTA-1 prevented tumor colonization in lung through in situ immune activation,and was slightly superior to the combined of Bec1 and PD-L1.Our findings highlight the promise of delivering immunostimulatory payloads via bionic carriers,eliciting automatic in situ activation of effector immune cells in tumor microenvironment for tumor eradication.All these results provide promising prospects into the application of immunoactivator in improving cancer synergistic immunotherapy to overcome the bottlenecks in clinic.

Tao-Hong-Si-Wu Decoction promotes angiogenesis after cerebral ischaemia in rats via platelet microparticles

Platelet microparticles(PMPs)are membrane particles derived from the platelet membrane that enter into the blood circulation.We sought to explore the therapeutic effects of Tao-Hong-Si-Wu Decoction(THSWD)on angiogenesis in a rat model of cerebral ischaemia-reperfusion(I/R).The protective effect of THSWD on I/R rats was observed morphologically by immunohistochemical expression of VEGF and CD34,along with immunofluorescence results of co-expression of Brd U and v WF.Then,PMPs from different groups of rats were extracted,and cytokine array analysis was used to screen for angiogenesis associated proteins.The results showed that THSWD can promote the expression of VEGF,CD34,Brd U and v WF.Cytokine array analysis revealed the changes in the expression of 29 related angiogenic proteins in the total protein of PMPs,which involved the Notch signalling pathway.Compared with model group,the expression levels of NICD and Hes-1 in the THSWD group were significantly increased.In the context of I/R,the angiogenesis-related proteins of PMPs are different.THSWD may involve the promotion of activation of the Notch signalling pathway to achieve therapeutic effects on cerebral ischaemia.

Platelets in Kawasaki disease:Is this only a numbers game or something beyond?

Kawasaki disease(KD)is a medium vessel vasculitis with predilection to cause coronary artery abnormalities.KD is now the most common cause of acquired heart disease in developed countries.Thrombocytosis is consistently found in patients with KD,usually in 2nd to 3rd week of illness.Thrombocytopenia has occasionally been reported in the acute phase of KD.An increase or decrease in platelet number in patients with KD was initially considered to be a benign phenomenon.However,recent literature on platelet biology in KD has suggested that platelets are not only increasing but are rather activated.This phenomenon has been found to increase the risk of thrombosis in these patients.Similarly a fall in platelet counts during acute stage of KD has also been found to be associated with increased severity of disease.In this review,we update on the current best understanding about pathogenic role of platelets in patients with KD.