Multifunctional Nanoagent for Thrombus-Targeted Fibrinolytic Therapy

Abstract

Aims Current thrombolytic therapies rely upon exogenous plasminogen activators (PA) to effectively lyse clots, thereby restoring blood flow and preventing tissue and organ death. Yet, these PAs may also impair normal hemostasis which may lead to life-threatening bleeding, including intracerebral hemorrhage. Thus, the aim of this current study is to develop new thrombus-targeted fibrinolytic agents that harness the multifunctional theranostic capabilities of nanomaterials, potentially allowing for the generation of efficacious thrombolytics while minimizing deleterious side effects. Materials and Methods A thrombus-targeted nano-fibrinolytic agent (CLIO-FXIII-PEG-tPA) was synthesized using a magnetofluorescent crosslinked dextran-coated iron oxide (CLIO) nanoparticle platform that was conjugated to recombinant tissue plasminogen activator (tPA). Thrombus-targeting was achieved by derivatizing the nanoparticle with an activated factor XIII (FXIIIa)-sensitive peptide based on the amino terminus of α2-antiplasmin. Human plasma clot binding ability of the targeted and control agents was assessed by fluorescence reflectance imaging. Next, the in vitro enzymatic activity of the agents was assessed by S2288-based amidolytic activity, and an ELISA D-dimer assay for fibrinolysis. In vivo targeting of the nanoagent was next examined by intravital fluorescence microscopy of murine arterial and venous thrombosis. The fibrinolytic activity of the targeted nanoagent compared to free tPA was then evaluated in vivo in murine pulmonary embolism. Results In vitro, the targeted thrombolytic nanoagent demonstrated binding to fresh frozen plasma (FFP) clots superior to control nanoagents (ANOVA p < 0.05). On a weight (mg) basis, the S2288 amidolytic efficiency of the targeted nanoagent was approximately 15% reduced compared to free tPA. When normalized by S2288-based activity, targeted, control, and free tPA samples demonstrated equivalent in vitro fibrinolytic activity against human plasma clots, as determined by ELISA D-dimer assays. The FXIIIa targeted fibrinolytic nanoagent efficiently bound the margin of intravascular thrombi as detected by IVFM. In in vivo fibrinolysis studies normalized for activity, the FXIIIa-targeted agent lysed pulmonary emboli with similar efficacy as free tPA (p>0.05). Conclusions The applicability of a FXIIIa-targeted thrombolytic nanoagent in the treatment of thromboembolism was demonstrated in vitro and in vivo. Future studies are planned to investigate the safety profile and overall efficacy of this class of nanoagents, and to further optimize their thrombus-targeting profile and lytic action.

Multifunctional, stimuli-sensitive nanoparticulate systems for drug delivery

“…The SPION acted as a magnetic resonance imaging (MRI) contrast agent, whereas the plasmid DNA suppressed the local immune response 48 . NDDSs for targeted thrombolytic therapy were developed by conjugating a thrombolytic agent (recombinant tissue plasminogen activator) to dextran-coated iron oxide nanoparticles, which were additionally modified with a thrombus-targeted peptide that was sensitive to activated factor XIII 49 . These NDDSs had increased binding to the margins of intravascular thrombi and good thrombolytic activity in a mouse model of pulmonary embolism.…”

Anti-candida, anti-coagulant and thrombolytic activities of biosynthesized silver nanoparticles using cell-free extract of Bacillus safensis LAU 13

“…The use of conventional therapies such as heparin, tissue plasminogen activator, urokinase, or streptokinase in the management of thrombosis have been plagued with complications of bleeding associated with reocclusion and reinfarction [14][15]. Among the innovative nanotechnological approaches being sought for in the management of thrombosis is the use of nanoparticles either as thrombolytic or anti-platelet agents [14,16] or as carriers of other thrombolytic agents [17]. Other applications of nanoparticles are in the in vivo visualization of thrombi using magnetic resonance imaging and computed tomography [15].…”

The Melding of Nanomedicine in Thrombosis Imaging and Treatment: a Review

“…The major advantage of these systems is the diversity of shapes that can be achieved whereas the polymeric architecture plays a critical role in their effectiveness [50]. Small changes in architecture might have an effect on solubility, drug loading capability and biodegradability.…”