Enzyme-responsive Hemostatic Elastin-like Polypeptides for Fibrin Stabilization and Enhanced Coagulation in Thrombocytopenia

Hemorrhage is a leading cause of mortality in trauma and surgery, particularly in thrombocytopenic patients with impaired platelet function. Current hemostatic therapies rely on plasma-derived products, but these are limited by logistical constraints and infectious risk. Here we report a recombinant protein-based hemostat that integrates biophysical design principles with clot-targeted drug delivery. We produced enzyme-responsive glutamine (Q)-containing block elastin-like polypeptides (Q-block-ELPs) that reinforce fibrin clots through phase separation and covalent cross-linking. Q-block-ELPs incorporate glutamine residues within a peptide motif recognized by coagulation factor XIIIa, enabling site-specific grafting into fibrin networks during clot formation. By tuning polymer length, Q-block valency, and lower critical solution temperature (LCST) behavior, we engineered Q-block-ELPs to phase separate at body temperature and integrate into the fibrin architecture. In vitro , Q-block-ELPs increase fibrin network density and stiffness. In a thrombocytopenic mouse model, systemic administration reduced blood loss and accelerated clot formation. This platform combines self-assembly with specific enzyme responsiveness to enhance clot mechanics and holds translational potential as a systemic hemostatic therapy in platelet-deficient bleeding disorders.