Heparin-Peptide Nanogranules for Thrombosis-Actuated Anticoagulation.

Despite nearly a century of clinical use as a blood thinner, heparin's rapid serum clearance and potential to induce severe bleeding events continue to urge the development of more effective controlled delivery strategies. Subcutaneous depots that steadily release the anticoagulant into circulation represent a promising approach to reducing overdose frequency, sustaining therapeutic concentrations of heparin in plasma, and prolonging anticoagulant activity in a safe and effective manner. Subcutaneously deliverable heparin-peptide nanogranules that allow for long-lasting heparin bioavailability in the circulatory system, while enabling on-demand activation of heparin's anticoagulant effects in the thrombus microenvironment, are reported. Biophysical studies demonstrate this responsive behavior is due to the sequestration of heparin within self-assembling peptide nanofibrils and its mechanically actuated decoupling to elicit antithrombotic effects at the clotting site. In vivo studies show these unique properties converge to allow subcutaneous nanogranule depots to extend heparin serum concentrations for an order of magnitude longer than standard dosing regimens while enabling prolonged and controlled anticoagulant activity. This biohybrid delivery system demonstrates a potentially scalable platform for the development of safer, easier to administer, and more effective antithrombotic nanotechnologies.