In vitro characterization of SynthoPlate™ (synthetic platelet) technology and its in vivo evaluation in severely thrombocytopenic mice

Abstract

Summary Background Platelet transfusion applications face severe challenges due to the limited availability and portability, high risk of contamination and short shelf-life of platelets. Therefore there is significant interest in synthetic platelet substitutes that can render hemostasis while avoiding these issues. Platelets promote hemostasis by injury site-selective adhesion and aggregation, and propagation of coagulation reactions on their membrane. Based on these mechanisms, we have developed a synthetic platelet technology (SynthoPlateTM) that integrates platelet-mimetic site-selective ‘adhesion’ and ‘aggregation’ functionalities via heteromultivalent surface-decoration of lipid vesicles with Von Willebrand Factor-binding, collagen-binding and active platelet integrin GPIIb-IIIa-binding peptides. Objective SynthoPlateTM was evaluated for its effects on platelets and plasma in vitro, and for systemic safety and hemostatic efficacy in severely thrombocytopenic mice in vivo. Methods In vitro, SynthoPlateTM was evaluated using aggregometry, fluorescence microscopy, microfluidics, and thrombin and fibrin generation assays. In vivo, SynthoPlateTM was evaluated for systemic safety using prothrombin and fibrin assays on plasma and for hemostatic effect on tail-transection bleeding time in severely thrombocytopenic (TCP) mice. Results SynthoPlateTM did not aggregate resting platelets or spontaneously promote coagulation in plasma, but could amplify recruitment and aggregation of active platelets at the bleeding site and thereby site-selectively enhance fibrin generation. SynthoPlateTM dose-dependently reduced bleeding time in TCP mice, to levels comparable to normal mice. SynthoPlateTM has a reasonable circulation residence time and is cleared mostly by the liver and spleen. Conclusion The results demonstrate the promise of SynthoPlateTM as a synthetic platelet substitute in transfusion treatment of platelet-related bleeding complications.

Platelet‐derived extracellular vesicles released after trauma promote hemostasis and contribute to DVT in mice

“…Mice were anesthetized and the tail tip (3 mm) was removed with a scalpel. Tails were submerged in PBS and bleeding was monitored as previously described . Bleeding time was quantified as the time from initiation of bleeding to the cessation of blood flow (seconds).…”

“…Tails were submerged in PBS and bleeding was monitored as previously described. 8,35 Bleeding time was quantified as the time from initiation of bleeding to the cessation of blood flow (seconds). Where noted mice were given 1-4 x 10 8 trauma-derived PEVs or equal volume PBS via penile vein injection 30 minutes before starting the tail bleed assay.…”

Enhanced Fibrinolysis with Magnetically Powered Colloidal Microwheels

“…Drug delivery via PA‐functionalized micro‐ and nanoparticles or blood cells is an alternative approach that can result in higher local concentrations and faster lysis than systemic administration of PA alone . When coupled with moieties that recognize fibrin(ogen) or transmembrane proteins on platelets, such particles can enhance accumulation at the surface of thrombi or take advantage of the unique fluid dynamics of a stenosed vessel . These approaches however rely on blood flow to deliver particles to the injury site, which requires particles in circulation prior to what is typically an acute and unpredictable thrombotic event.…”

Trauma‐targeted delivery of tranexamic acid improves hemostasis and survival in rat liver hemorrhage model

“…FMP‐decorated nanoparticles do not activate (and aggregate) quiescent platelets (Figure S1) but only interact with active platelets . Therefore, such particles do not have systemic pro‐thrombotic risk but provide an effective way to bind active platelet‐rich clots . The FMP was conjugated to the lipid DSPE‐PEG 2k ‐Azide via copper‐catalyzed cycloaddition (Figure A).…”

“…49 Therefore, such particles do not have systemic pro-thrombotic risk but provide an effective way to bind active platelet-rich clots. 50,51 The FMP was conjugated to the lipid DSPE-PEG 2k -Azide via copper-catalyzed cycloaddition ( Figure 3A).…”