Sustained thromboprophylaxis mediated by an RBC-targeted pro-urokinase zymogen activated at the site of clot formation

Sergei Zaitsev, Dirk Spitzer, Juan Carlos Murciano, Bi Sen Ding, Samira Tliba, M. Anna Kowalska, Oscar A. Marcos-Contreras, Alice Kuo, Victoria Stepanova, John P. Atkinson, Mortimer Poncz, Douglas B. Cines, Vladimir R. Muzykantov

Research output: Contribution to journalArticlepeer-review

86 Scopus citations

Abstract

Plasminogen activators (PAs) are used to treat life-threatening thrombosis, but not for thromboprophylaxis because of rapid clearance, risk of bleeding, and central nervous system (CNS) toxicity. We describe a novel strategy that may help to overcome these limitations by targeting a thrombin-activated PA pro-drug to circulating red blood cells (RBCs). We fused a single chain antibody (scFv Ter-119) that binds to mouse glycophorin A (GPA) with a variant human single-chain low molecular weight urokinase construct that can be activated selectively by thrombin (scFv/uPA-T). scFv/uPA-T bound specifically to mouse RBCs without altering their biocompatibility and retained its zymogenic properties until converted by thrombin into an active 2-chain molecule. As a result, RBC-bound scFv/uPA-T caused thrombin-induced fibrinolysis. One hour and 48 hours after intravenous (IV) injection in mice, approximately 70% and approximately 35% of scFv/uPA-T was retained in the blood, respectively, and approximately 95% of the circulating scFv/uPA-T remained bound to RBCs. A single IV injection of scFv/uPA-T provided effective prophylaxis against arterial and venous thrombosis for up to 24 hours. Thus, prophylactic delivery of RBC-targeted PA pro-drugs activated selectively at the site of clot formation represents a new approach to prevent thrombosis in clinical settings where the risk of clotting is high.

Original languageEnglish
Pages (from-to)5241-5248
Number of pages8
JournalBlood
Volume115
Issue number25
DOIs
StatePublished - Jun 24 2010

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