Thrombolysis effect of a novel targeted microbubble with low-frequency ultrasound in vivo

Abstract

Clot-targeted microbubbles (TMB) were developed based on oligopeptide specific to the glycoprotein IIb/IIIa receptor on active platelets. In this study, we aimed to elucidate the thrombolysis effect of this TMB in both intraarterial and intravenous application and compare the clot lysis efficiency of the TMB and untargeted microbubbles(UTMB) in presence of external low frequency ultrasound (LFUS) (800 kHz, 2.4 w/cm(2), pulse-wave). An acute arterial occlusion model was induced in rabbits by blocking the common carotid artery with an autogenous clot. Animals were randomized to five groups to receive the following treatment: 1) intra-arterial TMB and LFUS (IA TMB/LFUS); 2) intravenous TMB and LFUS (IV TMB/LFUS); 3) intravenous untargeted-microbubbles and LFUS (IV UTMB/LFUS); 4) LFUS only; 5) intra-arterial normal saline (NS) control. Declotting score and a variation of thrombolysis-in-myocardial-infarction (TIMI) flow scale were applied to assess clot clearance and flow restore according to the angiogram. IA TMB/LFUS treatment produced highest declotting score (3.5 +/- 0.53) and success rate (100%). IV TMB/LFUS treatment produced a higher declotting score (1.95 +/- 1.12) than LFUS treatment (0.53 +/- 0.38) (P = 0.026). and higher TIMI (1.94 +/- 0.62 vs. 0.47 +/- 0.44, P = 0.020). When administrated intravenously, TMB/LFUS created a higher declotting score (1.95 +/- 1.12) than that of UTMB/LFUS (0.61 +/- 0.43) (P = 0.033). The superiority was observed in TIMI also (1.94 +/- 0.62 vs. 0.72 +/- 0.25, P = 0.041). The results demonstrate that either intra-arterial or intravenous TMB is effective in clearing clot in-vivo model. The TMB showed advantage over UTMB in systemic administration.

Thrombolytic effects of a combined therapy with targeted microbubbles and ultrasound in a 6 h cerebral thrombosis rabbit model

“…The TMB and UTMB were prepared as described previously [14,15]. In brief, TMB was a product of an oligopeptide (P1 polypeptide) specific to the glycoprotein IIb/ IIIa receptor on active platelets during a chemical reaction with dipalmitoylphosphatidylethanolamine (DPPG; Avanti Polar Lipids, Alabaster, AL, USA) and distearoylphosphatidylethanolamine-polyethylene glycol-benzotriazole carbonate (MW = 3400) (DSPE-PEG-BTC, Shearwater Polymers, Huntsville, AL, USA) (DPPG: DSPE-PEG-BTC: peptide = 73:21:6, wt/wt).…”

“…In our previous studies, a novel TMB was prepared via loading P 1 polypeptide as a new inhibitor of the GPIIb/IIIa receptor and was confirmed to have high echogenicity, stability and good targeting to thrombus in vivo [14]. When combined with external low-frequency ultrasound (LFUS), this novel TMB was effective not only in dissolving thrombus and recanalizing an occluded vessel in a 0.5 h cerebral embolism rabbit model [15] but also in preventing rethrombosis in vivo [16]. Furthermore, compared to rt-PA, which is a common, approved thrombolytic drug in clinic, the risk of hemorrhage was reduced, and the fibrinolytic and coagulation systems were not affected [15].…”

“…When combined with external low-frequency ultrasound (LFUS), this novel TMB was effective not only in dissolving thrombus and recanalizing an occluded vessel in a 0.5 h cerebral embolism rabbit model [15] but also in preventing rethrombosis in vivo [16]. Furthermore, compared to rt-PA, which is a common, approved thrombolytic drug in clinic, the risk of hemorrhage was reduced, and the fibrinolytic and coagulation systems were not affected [15]. However, whether this TMB combined with LFUS could improve thrombolysis beyond the 0.5 h cerebral embolism rabbit model has not been certified.…”

Removing vascular obstructions: a challenge, yet an opportunity for interventional microdevices

“…For instance, in (Alonso et al 2009) the peak of negative pressure suitable to achieve thrombolysis is lowered from 6 MPa down to 1.56 MPa at 2 MHz thanks to the presence of microbubbles. Microbubble dose can be reduced using intra-arterial infusion via catheter (B. Wang et al 2008). In addition, preparation of functionalized, clottargeted microbubbles can further enhance treatment localization, augmenting thrombolysis efficiency while reducing systemic effects and risk of platelet aggregation and reocclusion .…”

Effects of low-frequency ultrasound combined with microbubbles on benign prostate hyperplasia

“…Low-frequency ultrasound and microbubble have been shown to accelerate thrombolysis in vitro and in vivo. 14,15 In addition, low frequency ultrasound has also been effective for suppressing tumour proliferation and for promoting tumour apoptosis.…”