Thrombolytic therapy based on P-selectin targeted polymer nanoparticles

Injection of tissue plasminogen activator (tPA) remains the standard treatment for thrombolysis. However, high doses have to be administered with the risk to cause hemorrhages [1]. In our work, tPA-loaded nanoparticles were... [ view full abstract ]

Injection of tissue plasminogen activator (tPA) remains the standard treatment for thrombolysis. However, high doses have to be administered with the risk to cause hemorrhages [1]. In our work, tPA-loaded nanoparticles were investigated to decrease the injected amount while keeping the same efficiency by ensuring a specific delivery. For this purpose, we synthesized polymer nanoparticles (NPs) targeting P-selectin as this protein is indeed a biomarker of activated platelets composing the thrombus.

Fluorescent polysaccharide-poly(isobutylcyanoacrylate) nanoparticles were synthesized by redox radical emulsion polymerization. They were functionalized with fucoidan (Fuco-NPs) as this anionic polysaccharide shows a nanomolar affinity for P-selectin [2]. Carboxymethyl-dextran was used as control (Control-NPs). To validate the targeting strategy, an in vitro flow assay was set up. Human whole blood was injected into collagen coated micro-channels to induce platelets activation and aggregation. Adhesion of NPs onto aggregates in venous conditions was quantified by fluorescence microscopy. tPA (Actilyse®) was loaded onto NPs by adsorption. The drug-related activity of the suspensions was measured in vitro and used to normalize the doses. Finally, an in vivo study was performed in a mouse model of mesenteric thrombosis induced by iron chloride.

Both NPs were similar in size, surface charge and fluorescence intensity. Fuco-NPs bound significantly more than Control-NPs to platelet aggregates confirming the potential of Fucoidan-functionalized NPs for targeting activated platelets (Figure A). The preclinical study showed that only Fuco-NPs-tPA were able to induce complete thrombolysis (4 mice out of 11) at a dose four times lower than the recommended one for murine models (Figure B). This result reinforced the choice of an active targeting approach, compare to other delivery strategies [3].

Fuco-NPs were efficient as carriers for thrombolysis enabling to decrease the injected tPA dose and therefore the risk of undesirable side effects. Although the variability between individuals is high in the developed model, this study underlines the great potential of targeted nanomedicine to fight thrombotic diseases.

[1] J. Alvazer-Sabin et al. Lancet Neurology 12(7) (2013)
[2] L. Bachelet et al. Biochimica et Biophysica Acta 1790(2) (2009)
[3] M. Varna et al. Future Science OA 1(4) (2015)