Encapsulation of fibrinogen and thrombin with calcium carbonate for hemorrhage control

Hemorrhage remains the major cause of death in combat and civilian trauma, although significant advances in hemostatic agents and blood products have enhanced damage control resuscitation and reduced mortality. Currently, few hemostats are available for cessation of non-compressible torso hemorrhage, e.g., intra-abdominal hemorrhage. To address this hard-to-solve problem, self-propelling hemostatic particles composed of coagulation factors e.g., fibrinogen, thrombin, CaCO3 and protonated tranexamic acid (TXA+) that can move against blood flow and promote clot formation have been developed. This paper describes the preparation and characterization of CaCO3-encapsulated fibrinogen/thrombin particles. The particles were prepared by interfacial reaction method using water-oil-water emulsion under different conditions that varied in the concentrations of the coagulation factor and ammonium carbonate solutions, amounts of surfactants, mixing speed, volume ratio between water and oil phases. The resulting CaCO3 encapsulated fibrinogen/thrombin particles were characterized via light microscopy for morphology, gel electrophoresis for presence of fibrinogen and thrombin, rotational thromboelastometry for hemostatic effects and reaction with TXA+ for self-propulsion test. It was found that CaCO3 particles had spherical structure with less than 10 µm in diameter, could encapsulate fibrinogen and thrombin, enhance blood coagulation, and generate bubbles for propulsion by reacting with TXA+. Moreover, when particles were combined with TXA+, a synergistic hemostatic effect was obtained. These hemostatic and self-propelling properties could be optimized via changes to preparation method and composition. Further studies in animal bleeding models are warranted.