Recombinant
tissue-type plasminogen activator (rtPA, or
Alteplase) is the first approved
thrombolytic drug for
acute ischemic stroke, but suffers from a short half-life and poor resistance to
plasminogen activator inhibitor (PAI-1), limiting its clinical use. The development of novel
thrombolytic agents with improved benefit/risk balance has always been of great significance. In this study, we identified a mutant of
serine protease domain of tPA (named ΔtPAA146V) capable of escaping the inhibition by endogenous
PAI-1 with 66-fold increased resistance compared to the wild type tPA. Based on this mutant, we generated a triple fusion ΔtPA (TriF-ΔtPA) containing
albumin and
fibrin binding
peptide(FBP). The fusion with
albumin effectively prolonged the plasma half-life of ΔtPA in mice to 144 min, which is much longer than ΔtPA and did not affect its thrombolytic activity. Furthermore, FBP rendered
fibrin specificity of the fusion
protein, giving a dissociation constant of ∼ 25 ± 0.9 μM. In a novel murine carotid
embolism-induced
stroke (CES) model, i.v. administration of TriF-ΔtPA promoted vascular recanalization, reduced
infarct volume, and mitigated neurobehavioral deficits more significantly compared to ΔtPA-HSA or
Alteplase, showing little
bleeding risk. Together, this long-acting PAI-1-resistant
thrombolytic agent holds great potential for clinical applications.