Research ArticleHEALTH AND MEDICINE

Accelerating thrombolysis using a precision and clot-penetrating drug delivery strategy by nanoparticle-shelled microbubbles

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Science Advances  29 Jul 2020:
Vol. 6, no. 31, eaaz8204
DOI: 10.1126/sciadv.aaz8204
  • Fig. 1 Precision delivery strategy using the magnetic targeting and ultrasound-triggered release.

    (A) Illustration of targeted delivery and controlled release for thrombolysis. (B) Illustration of the synthesis of nanomedicine-shelled microbubble (i.e., MMB-SiO2-tPA).

  • Fig. 2 Preparation, characterization, tPA activity maintenance of MMB-SiO2-tPA, and controlled tPA release.

    (A) Environmental scanning electron microscope image of MMB-SiO2-tPA in bright field mode. Scale bar, 10 μm. (B) Scanning electron microscopy and elemental mapping of a single MMB-SiO2-tPA. Scale bar, 5 μm. (C) The diameter distribution of the MMB-SiO2-tPA; n = 200. (D) Contents of iron and silicon in different volumes of MMB-SiO2-tPA quantified by ICP-OES. (E) Content of thrombolytic drug (tPA) in different volumes of MMB-SiO2-tPA by BCA assay. (F) Counting MMB-SiO2-tPA in different volumes of solutions. (G) In vitro enzymatic activity of native tPA, SiO2-tPA, and MMB-SiO2-tPA versus time in the presence of plasminogen activator inhibitor-1 (PAI-1). (H) The retained activity of tPA after 3 and 12 hours in the presence of PAI-1. (I) Cumulative release profiles of thrombolytic drug tPA from MMB-SiO2-tPA at different acoustic pressure of ultrasound. Error bars in all figures indicated the standard divisions by at least triplicate experiments.

  • Fig. 3 Ultrasound imaging of thrombi after intravenous injection of MMB-SiO2-tPA in a femoral vein thrombi–bearing mouse model.

    (A) Schematic illustration of the ultrasound imaging and magnetic targeting process in a femoral vein thrombosis model. (B) In vitro ultrasound phantom images of MMB-SiO2-tPA in B mode and contrast mode. (C) In vivo ultrasound images of femoral vein thrombi before and after MMB-SiO2-tPA injection in B mode and contrast mode. A magnet was placed adjacent to the femoral vein after 5 min after MMB-SiO2-tPA injection. (D) The acoustic intensities of the interested area (red frame) quantified in ultrasound phantom images. a.u., arbitrary units. (E) The acoustic intensities of the interested area (red frame) quantified in ultrasound images of the mouse model. Error bars in all figures indicated the standard divisions by at least triplicate experiments.

  • Fig. 4 In vitro fibrin-lysis assay by a vertical-channel gel system composed of agarose-fibrin.

    (A) Schematic diagrams and representative photographs of the fibrinolytic process of the agarose-fibrin gel incubated with saline, native tPA, SiO2-tPA, and MMB-SiO2-tPA at different thrombolysis times, respectively. (B) Quantification of fibrinolytic area of fibrin over time incubated with saline, native tPA, SiO2-tPA, and MMB-SiO2-tPA (n = 5; ***P < 0.001). (C) The mean fibrinolytic rate of fibrin at different time intervals incubated with native tPA, SiO2-tPA, and MMB-SiO2-tPA (n = 5).

  • Fig. 5 Assessment of dissolution efficiency in ex vivo blood clots.

    (A) Schematic illustration of the blood clot dissolution treatment process under the magnetic field combined with low-intensity ultrasound. (B) Representative images of the thrombolysis processes at 0, 3, 6, 9, and 12 hours after being treated by saline, native tPA, SiO2-tPA, and MMB-SiO2-tPA, respectively. (C) Quantification of the dissolution efficiency by measuring the mass loss of the blood clot at 3 hours after treatments. (D) Quantification of the dissolution efficiency by measuring the mass loss of the blood clot at 12 hours after treatments. (E) Absorbance values (λ = 540 nm) of the supernatants at 12 hours after treatments; n = 5; *P < 0.05, **P < 0.01, and ***P < 0.001.

  • Fig. 6 Low-intensity ultrasound improves the efficacy of femoral vein thrombolysis in a mouse model.

    (A) Schematic illustration of the treatment procedures of a femoral vein thrombosis mouse model. (B) Representative images of thrombolysis evaluation after treatment with saline, native tPA, SiO2-tPA, and MMB-SiO2-tPA, respectively. The white arrows indicate the inducted thrombi (n = 4). (C) Representative histological analysis of the femoral vein after treatment with saline, native tPA, SiO2-tPA, and MMB-SiO2-tPA for 12 hours, respectively (n = 4). Scale bar, 50 μm. (D) Quantification of the thrombus area (% vein lumen) in femoral vein in different treatment groups (n = 4). (E) Representative histological analysis of the femoral vein after administration and magnetic targeting of MMB-SiO2-tPA with or without low-intensity ultrasound. The red arrow indicates the enrichment of MMB-SiO2-tPA, and the red circles indicate the MMB-SiO2-tPA with an intact structure. Scale bars, 50 μm.

Supplementary Materials

  • Supplementary Materials

    Accelerating thrombolysis using a precision and clot-penetrating drug delivery strategy by nanoparticle-shelled microbubbles

    Siyu Wang, Xixi Guo, Weijun Xiu, Yang Liu, Lili Ren, Huaxin Xiao, Fang Yang, Yu Gao, Chenjie Xu, Lianhui Wang

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