Antithrombin nanoparticles inhibit stent thrombosis in ex vivo static and flow models

Abstract

Introduction Despite significant advances in intravascular stent technology, safe prevention of stent thrombosis over prolonged periods after initial deployment persists as a medical need to reduce device failure. The objective of this project was to assess the potential of perfluorocarbon nanoparticles conjugated with the direct thrombin inhibitor D-phenylalanyl-L-prolyl-L-arginyl chloromethylketone (PPACK-NP) to inhibit stent thrombosis. Methods In a static model of stent thrombosis, 3 mm × 3 mm pieces of stainless steel coronary stents were cut and adsorbed with thrombin to create a procoagulant surface that would facilitate thrombus development. Following treatment with PPACK-NP or control NP, stents were exposed to platelet poor plasma (PPP) or platelet rich plasma (PRP) for set time points up to 60 minutes. Measurements of final clot weight in grams were utilized for assessing the effect of nanoparticle treatment on limiting thrombosis. Additionally, groups of stents were exposed to flowing plasma containing various treatments (saline, free PPACK, control NP and PPACK-NP) and generated thrombi were stained and imaged to investigate the treatment effects of PPACK-NP under flow conditions. Results The static model of stent thrombosis utilized in this study indicated a significant reduction in thrombus deposition with PPACK-NP treatment (0.00067 ± 0.00026g, N=3) compared to control NP (0.0098 ± 0.0015g, N=3, p = 0.026) in PPP. Exposure to PRP demonstrated similar effects with PPACK-NP treatment (0.00033 ± 0.00012g, N=3) versus control NP treatment (0.0045 ± 0.00012g, N=3, p = 0.000017). In additional studies, stents were exposed to both platelet rich plasma pretreated with vorapaxar and PPACK-NP, which illustrated adjunctive benefit to oral platelet inhibitors for prevention of stent thrombosis. Additionally, an in vitro model of stent thrombosis under flow conditions established that PPACK-NP treatment significantly inhibited thrombus deposition on stents. Conclusion This study demonstrates that anti-thrombin perfluorocarbon nanoparticles exert marked focal anti-thrombin activity to prevent intravascular stent thrombosis and occlusion.

Neutralizing blood-borne polyphosphate in vivo provides safe thromboprotection

“…Development of materials with low propensity to cause contact activation would reduce the risk of device-associated thrombosis 63 . Similar to nanoparticle drug-eluting stents coupled with a direct thrombin inhibitor 64 , targeting procoagulant polyP by PPX immobilized on catheters, stents or artificial heart valves could provide a safe novel approach of anticoagulation that can be employed in FXII-related disease states. Furthermore, the enzymatic activity of PPX would facilitate degradation of multiple polyP molecules, potentially exceeding the antithrombotic activity of currently used anticoagulants such as thrombin and FXa inhibitors that target a single coagulation protease.…”

Recent Advances in the Development of Theranostic Nanoparticles for Cardiovascular Diseases

“…In addition, PPACK nanoparticles could specifically bind to acute thrombotic lesions and enable detection of the thrombus by MRI. In a follow-up study, Palekar et al [89,90] found that with the accumulation of thrombin in the coronary stent, PPACK nanoparticles continuously bound to and inactivated thrombin molecules on the surface, forming an "anti-coagulation" surface. Results showed that these PPACK perfluorocarbon nanoparticles were also able to prevent the formation of coronary stent thrombosis.…”

Antimicrobial Nanostructures for Neurodegenerative Infections

“…Nanoparticles and nanomedicines contribute to various pharmaceutical applications, like diagnosis of disease progression, drug delivery, and treatment of various ailments, such as cancer, thrombosis, wounds, osteoporosis, vertebral fracture, and microbial infective diseases, e.g., TB and HIV-associated opportunistic infections (Khajuria et al, 2014;Palekar et al, 2016;Sagar et al, 2015;Tang et al, 2015;Wolfram et al, 2015). Furthermore, it is expected that they will produce potential therapeutic agents for neuroinfective disorders.…”