A rat model of orthopedic injury-induced hypercoagulability and fibrinolytic shutdown

Abstract

Background-Post-injury hypercoagulability occurs in >25% of injured patients, increasing risk of thromboembolic complications despite chemoprophylaxis. However, few clinically relevant animal models of posttraumatic hypercoagulability exist. We aimed to evaluate a rodent model of bilateral hindlimb injury as a preclinical model of post-injury hypercoagulability.Methods-Forty Wistar rats were anesthetized with isoflurane: twenty underwent bilateral hindlimb fibula fracture, soft tissue and muscular crush injury, and bone homogenate injection intended to mimic the physiological severity of bilateral femur fracture. Twenty sham rats underwent anesthesia only. Terminal citrated blood samples drawn at 0, 6, 12, and 24h (n=5 per timed group) for analysis by native thromboelastography (TEG) in the presence and absence of taurocholic acid (TUCA) to augment fibrinolysis. Plasminogen activator inhibitor 1 (PAI-1) and alpha-2 antiplasmin (A2AP) levels in plasma were assessed via ELISA.Results-Injured rats became hypercoagulable relative to baseline by 6h based on TEG MA and G (p<0.005); sham rats became hypercoagulable to a lesser degree by 24h (p<0.005). Compared to sham animals, injured rats were hypercoagulable by MA and G within 6h of injury, remained hypercoagulable by MA and G through at least 24h (all p<0.01), and showed impaired fibrinolysis by TUCA LY30 at 12h (p=0.019) and native LY30 at 24h (p=0.045).

Changes in Thrombelastography in Patients with Acute Exacerbation of Chronic Obstructive Pulmonary Disease and the Relationship with Lung Function

“…The enhanced fibrinogen activity in the patients enrolled in this study may be explained by the fact that during acute exacerbations of COPD, due to the presence of a hypercoagulable state of the blood, fibrinogen is not only involved in the endogenous and exogenous coagulation process as a coagulation factor but can also act as an acute phase response protein, triggering platelet aggregation and increasing blood viscosity; and elevated fibrinogen provides more substrates for enzymatic reactions in the coagulation process and also causes a marked increase in the aggregation of red blood cells, reducing the speed of blood flow and stagnation of blood, thus promoting thrombosis; In addition, recurrent lung infections and chronic inflammatory processes can also lead to increased fibrinogen and enhanced activity [ 27 ]. MA mainly reflects platelet function, and when MA is elevated it indicates increased platelet activity and a hypercoagulable state of blood [ 28 ]. Long-term hypoxia and inflammatory stimulation damage the vascular endothelial system of AECOPD patients, after endothelial damage, subintimal collagen fibers are exposed and release tissue factors, and platelets gather, which then affect the production of anticoagulant factors and the balance of the pulmonary vascular internal environment, so as to start endogenous and exogenous coagulation, resulting in the imbalance of coagulation function and fibrinolytic system; Inflammatory mediators and inflammatory factors released by inflammatory cells following damage to the vascular endothelium in patients with AECOPD, which not only damage lung tissue structure and increase airway inflammation but also interact with platelets and enhance platelet activity; In addition, chronic tobacco and toxic particle irritation can inhibit prostacyclin synthesis in the blood, which enhances the action of thromboxane A2, which can also trigger platelet aggregation and increase platelet activity [ 29 ].…”

Chinese expert consensus on diagnosis and treatment of trauma-induced hypercoagulopathy

“…1). High circulating actin and myosin released due to cell death can also promote clot propagation and fibrinolysis shutdown, reflected in low TEG LY30%, high α angle, and elevated levels of plasminogen activator inhibitor type-1 (PAI-1) [25,26]. Moreover, uncontrolled systemic release of endogenous damage-associated molecular patterns (DAMPs) after trauma triggers inflammasomes to activate caspases, which leads in turn to the release of interleukin-1β and interleukin-18 as well as promotes pyroptosis [27].…”

The α-globin chain of hemoglobin potentiates tissue plasminogen activator induced hyperfibrinolysis in vitro

“…[28][29][30][31] Thus, in the severely injured, the tPA:PAI-1 balance seems to be of importance in tipping the state of fibrinolysis toward the extremes of HF or SD; however, the triggers for HF and SD remain undefined. [26][27][28][29][30][31] In short, severe injury causes the release of intracellular proteins into the circulation many of which may bind or interact with plasma proteins including PAI-1 or tPA. 24,[32][33][34] Hemoglobin is the most abundant intracellular protein in RBCs and hemoglobinbased oxygen carriers potentiate HF in vitro in tPA-challenged TEGs from healthy volunteers.…”

“…15,[25][26][27] Conversely, SD has been associated with increases in PAI-1 in patients postoperatively and trauma patients, the source of which is likely from platelets, endothelial cells, or organ parenchyma. [28][29][30][31] Thus, in the severely injured, the tPA:PAI-1 balance seems to be of importance in tipping the state of fibrinolysis toward the extremes of HF or SD; however, the triggers for HF and SD remain undefined. [26][27][28][29][30][31] In short, severe injury causes the release of intracellular proteins into the circulation many of which may bind or interact with plasma proteins including PAI-1 or tPA.…”

“…Elevated tPA levels are associated with HF through plasmin activation, and similarly, patients with congenital plasminogen activator inhibitor 1 (PAI-1) deficiency may develop HF 15,25–27 . Conversely, SD has been associated with increases in PAI-1 in patients postoperatively and trauma patients, the source of which is likely from platelets, endothelial cells, or organ parenchyma 28–31 . Thus, in the severely injured, the tPA:PAI-1 balance seems to be of importance in tipping the state of fibrinolysis toward the extremes of HF or SD; however, the triggers for HF and SD remain undefined 26–31 …”