N-Acetyl Cysteine Prevents Arterial Thrombosis in a Dose-Dependent Manner In Vitro and in Mice.

BACKGROUND: Platelet-rich thrombi occlude arteries causing fatal infarcts like heart attacks and strokes. Prevention of thrombi by current antiplatelet agents can cause major bleeding. Instead, we propose using N-acetyl cysteine (NAC) to act against the protein VWF (von Willebrand factor), and not platelets, to prevent arterial thrombi from forming. METHODS: NAC was assessed for its ability to prevent arterial thrombosis by measuring platelet accumulation rate and occlusion time using a microfluidic model of arterial thrombosis with human blood. Acute clot formation, clot stability, and tail bleeding were measured in vivo with the murine modified Folts model. The effect of NAC in the murine model after 6 hours was also measured to determine any persistent effects of NAC after it has been cleared from the blood. RESULTS: We demonstrate reduction of thrombi formation following treatment with NAC in vitro and in vivo. Human whole blood treated with 3 or 5 mmol/L NAC showed delayed thrombus formation 2.0× and 3.7× longer than control, respectively (P<0.001). Blood treated with 10 mmol/L NAC did not form an occlusive clot, and no macroscopic platelet aggregation was visible (P<0.001). In vivo, a 400-mg/kg dose of NAC prevented occlusive clots from forming in mice without significantly affecting tail bleeding times. A lower dose of NAC significantly reduced clot stability. Mice given multiple injections showed that NAC has a lasting and cumulative effect on clot stability, even after being cleared from the blood (P<0.001). CONCLUSIONS: Both preclinical models demonstrate that NAC prevents thrombus formation in a dose-dependent manner without significantly affecting bleeding time. This work highlights a new pathway for preventing arterial thrombosis, different from antiplatelet agents, using an amino acid derivative as an antithrombotic therapeutic.

Novel tubing connectors reduce ECMO circuit thrombosis.

BACKGROUND: Thrombosis within extracorporeal membrane oxygenation (ECMO) circuits is a common complication that dominates clinical management of patients receiving mechanical circulatory support. Prior studies have identified that over 80% of circuit thrombosis can be attributed to tubing-connector junctions. METHODS: A novel connector was designed that reduces local regions of flow stagnation at the tubing-connector junction to eliminate a primary source of ECMO circuit thrombi. To compare clotting between the novel connectors and the traditional connectors, both in vitro loops and an in vivo caprine model of long-term (48 h) ECMO were used to generate tubing-connector junction clots. RESULTS: In vitro, the traditional connectors uniformly (9/9) formed large thrombi, while novel connectors formed a small thrombus in only one of nine (p < 0.0001). In the long-term goat ECMO circuits, the traditional connectors exhibited more thrombi (p < 0.04), and these thrombi were more likely to protrude into the lumen of the tubing (p < 0.001). CONCLUSION: Both in vitro and in vivo validation experiments successfully recreated circuit thrombosis and demonstrate that the adoption of novel connectors can reduce the burden of circuit thrombosis.

Design of functionalized cyclic peptides through orthogonal click reactions for cell culture and targeting applications.

An approach for the design of functionalized cyclic peptides is established for use in 3D cell culture and in cell targeting. Sequential orthogonal click reactions, specifically a photoinitiated thiol-ene and strain promoted azide-alkyne cycloaddition, were utilized for peptide cyclization and conjugation relevant for biomaterial and biomedical applications, respectively.