Molecular requirements for safer generation of thrombolytics by bioengineering the tissue-type plasminogen activator A chain

Background Thrombolysis with tissue-type plasminogen activator (t-PA) is the only treatment approved for acute ischemic stroke. Although t-PA is an efficient clot lysis enzyme, it also causes damage to the neurovascular unit, including hemorrhagic transformations and neurotoxicity. Objectives On the basis of the mechanism of action of t-PA on neurotoxicity, we aimed at studying the molecular requirements to generate safer thrombolytics. Methods We produced original t-PA-related mutants, including a non-cleavable single-chain form with restored zymogenicity (sc*-t-PA) and a t-PA modified in the kringle2 lysine-binding site (K2*-t-PA). Both sc*-t-PA and K2*-t-PA showed fibrinolytic activities similar to that of wild-type t-PA on both euglobulin-containing and plasma-containing clots. In contrast to wild-type t-PA, the two mutants did not promote N-methyl-d-aspartate receptor-mediated neurotoxicity. Conclusions We designed t-PA mutants with molecular properties that, in contrast to t-PA, do not induce neurotoxicity.