Platelet-like particles for augmenting hemostasis

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Project Abstract Uncontrolled bleeding represents a significant clinical challenge in general surgery, trauma, and emergency medicine. Exsanguination (bleeding) is the major cause of death from traumatic injury (~ 40%) and bleeding following invasive surgeries such as cardiopulmonary bypass is associated with significant morbidity and mortality. During the normal clotting cascade, the protease thrombin is activated, which in turn activates dormant circulating platelets and the clotting protein precursor, fibrinogen. Activated platelets form a hemostatic plug at the site of injury, stemming blood loss. Platelets are sufficient to achieve short-term hemostasis and are critical to the maturation of stable fibrin-based clots via their activity in fibrin recruitment and clot contraction. Thus, it is not surprising that their massive dilution during hemorrhage or active inhibition during surgery results in a failure of the clotting system. Current hemostasis technologies include topical sealants, exothermic zeolites and recombinant clotting factors. Each of these approaches has demonstrated modest successes, yet all have significant drawbacks such as a lack of wound specificity; none are as “evolved” as the natural wound-responsive hemostasis system. Thus, more recent efforts have focused on creation of synthetic analogs of platelets. The vital platelet functions that one would like to recapitulate include injury-triggered enhancement of fibrin clot formation and clot contraction/stabilization. To date, artificial platelet approaches only recapitulate clot/platelet binding in a non-triggered (i.e. constitutive) and non-specific fashion and lack the other critical platelet functions. Here we propose a novel and simple approach to the creation of platelet-like structures through the application of synthetic biology. We are proposing two aims. The first aim is to understand how our platelet-like particles interact with various stages of the coagulation cascade and to understand the fundamental mechanism of action of our platelet-like particles in augmenting hemostasis. The second aim is to explore the in vivo function of the platelet-like particles, specifically in the augmentation of hemostasis in multiple models of trauma-associated coagulopathy.