Procoagulant activity induced by transcatheter closure of atrial septal defects is associated with exposure of phosphatidylserine on microparticles, platelets and red blood cells

Pb-Induced Eryptosis May Provoke Thrombosis Prior to Hemolysis

Lead (Pb) is a common metal, which can be toxic to the human body via the pollution of water or food, and can cause anemia and other diseases. However, what happens before hemolysis and anemia caused by Pb poisoning is unclear. Here, we demonstrated Pb can cause procoagulant activity of erythroid cells leading to thrombosis before hemolysis. In freshly isolated human erythroid cells, we observed that Pb resulted in hemolysis in both concentration- and time-dependent manners, but that no lysis occurred in Pb-exposed erythroid cells (≤20 μM for 1 h). Pb treatment did not cause shape changes at up to 0.5 h incubation but at 1 h incubation echinocyte and echino-spherocyte shape changes were observed, indicating that Pb can exaggerate a concentration- and time-dependent trend of shape changes in erythroid cells. After Pb treatment, ROS-independent eryptosis was shown with no increase of reactive oxygen species (ROS), but with an increase of [Ca2+]i and caspase 3 activity. With a thrombosis mouse model, we observed increased thrombus by Pb treatment (0 or 25 mg/kg). In brief, prior to hemolysis, we demonstrated Pb can cause ROS-independent but [Ca2+]i-dependent eryptosis, which might provoke thrombosis.

Antiplatelet and Antithrombotic Therapy After Patent Foramen Oval and Atrial Septal Defect Closure

Pathologies of the atrial septum include different interatrial communications varying from patent foramen ovale (PFO) to actual defects. Atrial septal defects (ASDs) may be localized within the fossa ovalis such as the secundum type ASD or outside the region of fossa ovalis, such as the ostium primum defect and sinus venosus defect. Over the last decades, the percutaneous closure of interatrial shunts has become a feasible and safe method. During these procedures, the delicate balance between thrombotic risk, device sealing process and bleeding risk is crucial. In this review, we sought to describe current available data on the antiplatelet and antithrombotic management of patients after percutaneous ASD or PFO closure.

New insights into sinusoidal obstruction syndrome

BACKGROUND

Entry criteria included patients who developed sinusoidal obstruction syndrome (SOS) at a single centre from January 2000 to December 2011. Patients who underwent haemopoietic stem cell transplantation or actinomicyn-based chemotherapy for nephroblastoma were selected. The study group comprised five patients with SOS who were compared with a control group of seven patients without SOS.

AIM

To study the relationships between endothelial extracellular vesicles (EV) and plasminogen-activator inhibitor type 1(PAI-1) to assess their modification in the early phase of SOS.

METHODS

Consecutive blood samples were tested for cell-derived EV, PAI-1 and coagulation parameters. Any statistically significant correlation between all datasets was searched.

RESULTS

Antithrombin level and platelet count were statistically significantly reduced in SOS patients, suggesting a consumption status. PAI-1:Ag and PAI-1:act showed an inverse relationship with platelet counts (coef. -0.034, SE = 0.016; P = 0.041 and -0.052, SE = 0.019; P = 0.011 respectively). During follow up, PAI-1:Ag was inversely related to EV CD144+ (coef. -0.261, SE = 0.094; P = 0.007) and antithrombin (coef -0.509, SE = 0.175; P = 0.005). PAI-1:act showed an inverse association with EV CD144+ (coef.-0.251, SE = 0.121; P = 0.043), EV CD31+/CD41+ (coef. -0.004, SE = 0.002; P = 0.026) and antithrombin (coef. -0.470, SE = 0.220; P = 0.038). EV generated by rupture of gap junctions (EV CD144+) were increased in SOS patients and also showed a change over time.

CONCLUSION

This study demonstrates the existence of an ongoing procoagulant and hypofibrinolytic status in SOS, indicating a possible role for anticoagulant therapy. Moreover, these findings suggest a role for EV CD 144+, either alone or in combination with PAI-1, as a new biomarker for SOS.

Enhanced procoagulant activity of platelets after chemotherapy in non-small cell lung cancer

The procoagulant status of patients with non-small cell lung cancer (NSCLC) after chemotherapy is poorly characterized and the role of platelets in hypercoagulative state of NSCLC is unknown. The aim of this study was to evaluate the procoagulant activity (PCA) of platelets in NSCLC before and after chemotherapy. The subjects were 52 patients newly diagnosed with NSCLC. The patients had decreased clotting time compared with healthy subjects, and the thrombin-antithrombin complex increased 2.5-fold after chemotherapy. Platelets in the patients after chemotherapy had enhanced phosphatidylserine (PS) exposure, and shortened coagulation time as well as increased thrombin and fibrin formation of platelets compared with those before chemotherapy. Platelet-derived microparticles increased 2-fold at day 1 and peaked at day 2 post-chemotherapy. Treatment of cisplatin in vitro also resulted in upregulated intrinsic FXa and thrombin formation on platelets with a dose-dependent manner. Platelets treated with aspirin significantly decreased PCA. However, lactadherin blocked PS and inhibited the PCA approximately by 70%. Seven days after chemotherapy, PCA of platelets restored to the baseline as that before chemotherapy, indicating that within a week of chemotherapy patient platelets are highly procoagulant and effective intervention should be taken in case of thrombosis. Our results suggested that platelets after chemotherapy had elevated PCA and may contribute to the hypercoagulative state of NSCLC. Prophylactic anti-coagulant combined with anti-platelet therapy may play an inhibitory role in thrombotic complications in NSCLC.

Cellular microparticles and pathophysiology of traumatic brain injury

Traumatic brain injury (TBI) is a leading cause of death and disability worldwide. The finding that cellular microparticles (MPs) generated by injured cells profoundly impact on pathological courses of TBI has paved the way for new diagnostic and therapeutic strategies. MPs are subcellular fragments or organelles that serve as carriers of lipids, adhesive receptors, cytokines, nucleic acids, and tissue-degrading enzymes that are unique to the parental cells. Their sub-micron sizes allow MPs to travel to areas that parental cells are unable to reach to exercise diverse biological functions. In this review, we summarize recent developments in identifying a casual role of MPs in the pathologies of TBI and suggest that MPs serve as a new class of therapeutic targets for the prevention and treatment of TBI and associated systemic complications.

Dissimilarity of increased phosphatidylserine-positive microparticles and associated coagulation activation in acute coronary syndromes

OBJECTIVE

We evaluated cellular origin, numbers, and procoagulant activity of phosphatidylserine-positive microparticles (MPs) among subgroups in acute coronary syndromes (ACS).

MATERIALS AND METHODS

Parameters were measured on admission, days 1 (within 24 h of admission), 2, 3, and 7. All ST-elevated myocardial infarction (STEMI) patients presented more than 3 h from symptom onset and received fibrinolysis treatment; controls included unstable angina and non-STEMI patients as well as healthy controls. Phosphatidylserine-positive MPs were detected by flow cytometry, whereas procoagulant activity was assessed by coagulation time, purified coagulation complex assays, and fibrin formation. MP-induced fibrins were visualized by confocal microscopy.

RESULTS

On admission, the total MP count was ∼2.5-fold higher in the ACS groups compared with the healthy controls (P<0.05), primarily originating from platelets and endothelial cells, and there were no significant differences among ACS subgroups. Specifically, leukocyte-derived and erythrocyte-derived MPs were higher in the STEMI group compared with unstable angina and non-STEMI groups (both P<0.05). Further, MPs from the ACS groups reduced coagulation time by 27.5% and induced intrinsic and extrinsic FXase, prothrombinase, and fibrin formation by 2.8-, 2.3-, 2.5-, and 1.7-fold, respectively (P<0.05 for all), whereas blocking phosphatidylserine with lactadherin inhibited ∼70% of procoagulant activity. MP number and concomitant coagulation decreased significantly by day 2 and continued to decrease gradually during the recovery period.

CONCLUSION

This study shows that MP characteristics from circulating blood may be used as prognostic indicators to reflect the origin cell of activation and thrombophilic states found in ACS subgroups.

Microparticles and blood cells induce procoagulant activity via phosphatidylserine exposure in NSTEMI patients following stent implantation

BACKGROUND

Relatively little is known about the role of phosphatidylserine (PS) in procoagulant activity (PCA) in patients with non-ST-elevated myocardial infarction (NSTEMI) after stent implantation. This study was designed to evaluate whether exposed PS on microparticles (MPs) and blood cells were involved in the hypercoagulable state in NSTEMI patients with stent implantation.

METHODS

NSTEMI patients (n=90) and healthy controls (n=20) were included in our study. PS exposure on MPs and blood cells was analyzed with flow cytometer and confocal microscope. PCA was evaluated by clotting time, purified coagulation complex assays and fibrin production assays.

RESULTS

Baseline levels of MPs and PS⁺ blood cells were significantly higher (P<0.001) in the patients than in controls. After stent implantation, a remarkable increase was observed in both MPs and PS⁺ blood cells. Specifically, PS⁺ MPs, PS⁺ platelets and erythrocytes peaked at 18h following stent implantation, while PS⁺ leukocytes peaked on day 2. In addition, circulating MPs (mostly derived from platelets, leukocytes, erythrocytes and endothelial cells) cooperating with PS⁺ blood cells, contributed to markedly shortened coagulation time and markedly increased FXa/thrombin/fibrin (all P<0.01) generation in patient group. Moreover, blockade of exposed PS on MPs and cells with lactadherin inhibited PCA by approximately 70%.

CONCLUSIONS

Our results suggest that PS⁺ MPs and blood cells play a procoagulant role in NSTEMI patients following stent implantation. Blockade of PS could become a novel therapeutic modality for the prevention of thrombosis in these patients.