New Approaches in Nanomedicine for Ischemic Stroke

Ischemic stroke, caused by the interruption of blood flow to the brain and subsequent neuronal death, represents one of the main causes of disability in developed countries. Therapeutic methods such as recanalization approaches, neuroprotective drugs, or recovery strategies have been widely developed to improve the patient’s outcome; however, important limitations such as a narrow therapeutic window, the ability to reach brain targets, or drug side effects constitute some of the main aspects that limit the clinical applicability of the current treatments. Nanotechnology has emerged as a promising tool to overcome many of these drug limitations and improve the efficacy of treatments for neurological diseases such as stroke. The use of nanoparticles as a contrast agent or as drug carriers to a specific target are some of the most common approaches developed in nanomedicine for stroke. Throughout this review, we have summarized our experience of using nanotechnology tools for the study of stroke and the search for novel therapiesThis project was supported by the FRQS, ISCIII (AC19/00031 and AC20/00041), and ANR under the framework of EuroNanoMed III_2020 (PLATMED_project); the European Union program FEDER and the European Regional Development Fund–ERDF; and the Xunta de Galicia (IN607D2020/03 and ED431G2019/03). E.P. and B.P acknowledge the AEI grants (PID2019-111218RB-I00 and RyC-2017-23457). Finally, F.C. thanks the ISCIII and Miguel Servet program (CPII19/00020)S

HMGB-1 promotes fibrinolysis and reduces neurotoxicity mediated by tissue plasminogen activator.

International audienceOwing to its ability to generate the clot-dissolving protease plasmin, tissue plasminogen activator (tPA) is the only approved drug for the acute treatment of ischemic stroke. However, tPA also promotes hemorrhagic transformation and excitotoxic events. High mobility group box-1 protein (HMGB-1) is a non-histone transcription factor and a pro-inflammatory cytokine, which has also been shown to bind to both tPA and plasminogen. We thus investigated the cellular and molecular effects through which HMGB-1 could influence the vascular and parenchymal effects of tPA during ischemia. We demonstrate that HMGB-1 not only increases clot lysis by tPA, but also reduces the passage of vascular tPA across the blood-brain barrier, as well as tPA-driven leakage of the blood-brain barrier. In addition, HMGB-1 prevents the pro-neurotoxic effect of tPA, by blocking its interaction with N-methyl-D-aspartate (NMDA) receptors and the attendant potentiation of NMDA-induced neuronal Ca²⁺ influx. In conclusion, we show in vitro that HMGB-1 can promote the beneficial effects of tPA while counteracting its deleterious properties. We suggest that derivatives of HMGB-1, devoid of pro-inflammatory properties, could be used as adjunctive therapies to improve the overall benefit of tPA-mediated thrombolysis following stroke

Toward Safer Thrombolytic Agents in Stroke: Molecular Requirements for NMDA Receptor-Mediated Neurotoxicity

International audienceCurrent thrombolytic therapy for acute ischemic stroke with tissue-type plasminogen activator (tPA) has clear global benefits. Nevertheless, evidences argue that in addition to its prohemorrhagic effect, tPA might enhance excitotoxic necrosis. In the brain parenchyma, tPA, by binding to and then cleaving the amino-terminal domain (ATD) of the NR1 subunit of N-methyl-D-aspartate (NMDA) glutamate receptors, increases calcium influx to toxic levels. We show here that tPA binds the ATD of the NR1 subunit by a two-sites system (K(D)=24 nmol/L). Although tenecteplase (TNK) and reteplase also display two-sites binding profiles, the catalytically inactive mutant TNKS478A displays a one-site binding profile and desmoteplase (DSPA), a kringle 2 (K2) domain-free plasminogen activator derived from vampire bat, does not interact with NR1. Moreover, we show that in contrast to tPA, DSPA does not promote excitotoxicity. These findings, together with three-dimensional (3D) modeling, show that a critical step for interaction of tPA with NR1 is the binding of its K2 domain, followed by the binding of its catalytic domain, which in turn cleaves the NR1 subunit at its ATD, leading to a subsequent potentiation of NMDA-induced calcium influx and neurotoxicity. This could help design safer new generation thrombolytic agents for stroke treatment