Platelet Functions During Extracorporeal Membrane Oxygenation. Platelet–Leukocyte Aggregates Analyzed by Flow Cytometry as a Promising Tool to Monitor Platelet Activation

Abstract

Extracorporeal membrane oxygenation (ECMO) is an extracorporeal circulation used to manage patients with severe circulatory or respiratory failure. It is associated with both high bleeding and thrombosis risks, mainly as a result of biomaterial/blood interface phenomena, high shear stress, and complex inflammatory response involving the activation of coagulation and complement systems, endothelial cells, leukocytes, and platelets. Besides their critical role in hemostasis, platelets are important players in inflammatory reactions, especially due to their ability to bind and activate leukocytes. Hence, we reviewed studies on platelet function of ECMO patients. Moreover, we addressed the issue of platelet–leukocyte aggregates (PLAs), which is a key step in both platelet and leukocyte activation, and deserves to be investigated in these patients. A reduced expression of GPIb and GPVI was found under ECMO therapy, due to the shedding processes. However, defective platelet aggregation is inconsistently reported and is still not clearly defined. Due to the high susceptibility of PLAs to pre-analytical conditions, defining and strictly adhering to a rigorous laboratory methodology is essential for reliable and reproducible results, especially in the setting of complex inflammatory situations like ECMO. We provide results on sample preparation and flow cytometric whole blood evaluation of circulating PLAs.

Synthetic Material Abdominal Swabs Reduce Activation of Platelets and Leukocytes Compared to Cotton Materials

“…However, thrombocytes have been reported to also liberate IL1β upon stimulation [35]. There is a strong mutual interaction and activation between platelets and leukocytes (especially neutrophils and macrophages) [36]. Therefore, the increase in leukocyte numbers only in the cotton group during HLM is likely related to the stimulation of proliferation and differentiation of neutrophil precursors by IL1β [30], which is released by either monocytes or platelets and can induce the mobilization of granulocyte progenitor cells and maturation of neutrophils in the bone marrow [37].…”

“…The latter is produced by activated monocytes [41]. Activated platelets secrete thrombocyte activating (e.g., platelet-activating factor, ADP, von Willebrand Factor, [42]) but also neutrophil-activating (neutrophil-activating peptide 2) and other inflammation-triggering mediators such as reactive oxygen species [36]. Therefore, the significantly higher activation of platelets, measured by β-TG release, in blood wrung from cotton could be responsible for the increased neutrophil activation.…”

Emerging Roles of Platelets in Allergic Asthma

“…Besides, a study documented that the inhibition of integrin aIIbb3 by tirofiban could significantly reduce the platelet-eosinophil aggregates and pulmonary eosinophil infiltration in allergic airways and reduce airway hyperresponsiveness and inflammation (72). Mechanistic studies further indicated that Mac-1 on eosinophils could interact with integrin aIIbb3 through a bridge molecule such as fibrinogen and sCD40L (73,74).…”

Characterization of Shear Stress Mediated Platelet Dysfunction: Data from an Ex Vivo Model for Extracorporeal Circulation and a Prospective Clinical Study

“…Balle et al demonstrated that patients with extracorporeal procedures have a reduced platelet adhesion, activation, and platelet aggregation during the ongoing procedure. 15,16 However, only limited data of published studies exist on this topic. So, we would like to introduce a sensitive and easy-to-use method to determine platelet activation status in whole blood (WB) after shear stress simulation, as by ECC, which may be helpful to assess the risk of both bleeding and thrombosis.…”