Fibrinogen γ‐chain peptide‐coated, ADP‐encapsulated liposomes rescue thrombocytopenic rabbits from non‐compressible liver hemorrhage

Summary.  Background:  We developed a fibrinogen γ-chain (dodecapeptide HHLGGAKQAGDV [H12])-coated, ADP-encapsulated liposome (H12-[ADP]-liposome) that accumulates at bleeding sites via interaction with activated platelets via glycoprotein IIb–IIIa and augments platelet aggregation by releasing ADP. Objective:  To evaluate the efficacy of H12-(ADP)-liposomes for treating liver hemorrhage in rabbits with acute thrombocytopenia. Methods:  Thrombocytopenia (platelets < 50 000 μL−1) was induced in rabbits by repeated blood withdrawal (100 mL kg−1 in total) and isovolemic transfusion of autologous washed red blood cells. H12-(ADP)-liposomes with platelet-poor plasma (PPP), platelet-rich plasma (PRP), PPP, ADP liposomes with PPP or H12-(PBS)-liposomes/PPP, were administered to the thrombocytopenic rabbits, and liver hemorrhage was induced by penetrating liver injury. Results:  Administration of H12-(ADP)-liposomes and of PRP rescued all thrombocytopenic rabbits from liver hemorrhage as a result of potent hemostasis at the liver bleeding site, although rabbits receiving PPP or ADP liposomes showed 20% survival in the first 24 h. Administration of H12-(ADP)-liposomes and of PRP suppressed both bleeding volume and time from the site of liver injury. H12-(phosphate-buffered saline)-liposomes lacking ADP also improved rabbit survival after liver hemorrhage, although their hemostatic effect was weaker. In rabbits with severe thrombocytopenia (25 000 platelets μL−1), the hemostatic effects of H12-(ADP)-liposomes tended to be attenuated as compared with those of PRP treatment. Histologic examination revealed that H12-(ADP)-liposomes accumulated at the bleeding site in the liver. Notably, neither macrothombi nor microthrombi were detected in the lung, kidney or liver in rabbits treated with H12-(ADP)-liposomes. Conclusions:  H12-(ADP)-liposomes appear to be a safe and effective therapeutic tool for acute thrombocytopenic trauma patients with massive bleeding.