Magnetic Nanoparticles Mediated Thrombolysis-A Review

Abstract

Nanoparticles containing thrombolytic medicines have been developed for thrombolysis applications in response to the increasing demand for effective, targeted treatment of thrombosis disease. In recent years, there has been a great deal of interest in nanoparticles that can be navigated and driven by a magnetic field. However, there are few review publications concerning the application of magnetic nanoparticles in thrombolysis. In this study, we examine the current state of magnetic nanoparticles in the application of in vitro and in vivo thrombolysis under a static or dynamic magnetic field, as well as the combination of magnetic nanoparticles with an acoustic field for dual-mode thrombolysis. We also discuss four primary processes of magnetic nanoparticles mediated thrombolysis, including magnetic nanoparticle targeting, magnetic nanoparticle trapping, magnetic drug release, and magnetic rupture of blood clot fibrin networks. This review will offer unique insights for the future study and clinical development of magnetic nanoparticles mediated thrombolysis approaches.

Keywords: Magnetic nanoparticles; magnetic microbubbles; magneto-sonothrombolysis; sonothrombolysis; thrombolysis; thrombolytic agents.

FIGURE 1.

A mix of different applications of magnetic nanoparticles (MNPs) in medicine, and the types of pathologies or medical conditions they are used for.

FIGURE 2.

Mechanism of magnetic nanoparticles enhanced thrombolysis. The process includes magnetic targeting of thrombolytic drugs, magnetic trapping of drug loaded magnetic nanoparticles, magnetic releasing for the drugs and magnetic disruption of the fibrin networks of clot.

FIGURE 3.

Illustration of magnetic targeting process: magnetic nanoparticles were delivered through a catheter and targeted at the clot site under magnetic force.

FIGURE 4.

Illustration of the magnetic nanoparticle trapped on targeted clot site under magnetic field.

FIGURE 5.

In-vitro thrombolysis with magnetic nanoparticles in a static magnetic field. (A) Targeted tPA@MNCs nanoparticles induce thrombolysis after treatments of 60, 245, and 620 minutes in a static magnetic field. The findings are as follows: (a) immediately after the tPA@MNCs are delivered to the thrombus site by the magnet, noticeable changes in the thrombus periphery are observed. This indicates that the tPA@MNCs have successfully reached the targeted area and are beginning to interact with the thrombus. (b) After 60 minutes, further changes in the thrombus are observed, suggesting that the tPA is being released from the nanocontainers and is initiating the process of clot breakdown. (c) At 245 minutes, additional progress in thrombolysis is seen, with the clot continuing to break down due to the ongoing activities of the released tPA. (d). Finally, after 620 minutes (approximately 10 hours) under static conditions, the thrombus is completely destroyed. Reproduced from [74], Copyright 2018, with the permission of IEEE. (B) The covalently bonded tPA on SPION^DexCOOH can dissolve agarose-fibrin matrices efficiently in the direction of the external magnetic field and the adsorptive method can only dissolve around the holes. Reproduced from [72], Copyright 2017, with the permission of IEEE. (C) Visualization of the plasma clot lysis process provided by magnetic thrombolytic composite using an optical microscope at 0 minutes, 45 minutes, and 90 minutes (a)–(c), X10 magnification. This fragmentation is characterized by an increase in the contact area between the surface of plasmin and the fibrin network, which leads to faster thrombolysis over time. Reproduced from [75], Copyright 2016, with the permission of IEEE.

FIGURE 6.

In-vivo thrombolysis with magnetic nanoparticles in a static magnetic field. (A) The study used T2-weighted and Vs3DI imaging techniques to monitor the in vivo thrombolysis after abdominal aorta injuries using MR. The treatment area (a1), (a2) was imaged before and after treatment with Fe3O4−PLGA-rtPA/CS-cRGD nanoparticles at 10 (b1), (b2), 20 (c1), (c2), 40 (d1), (d2), and 60 (e1), (e2) min. The T2-weighted images showed a decrease in the T2 signal at the mural thrombus and a widening of the hypointensity zone (red circles) at 10 and 20 min after injection. The Vs3DI images showed the formation of a thrombus in the rat abdominal aorta, and partial reappearance of the vessel lumen signal (red circles) was detected at 40 and 60 min after treatment with the nanoparticles. Reproduced from [90], Copyright 2014, with the permission of IEEE. (B) The results of histological examination of animals injected with saline, uPA, or MNPs@uPA. In the rat carotid artery, the saline group showed a white parietal clot containing multiple aggregates of adhered erythrocytes, dense fibrin, platelets, and leukocytes. In contrast, only single adherent erythrocytes near the inner wall of the vessel were observed in animals injected with MNPs@uPA, while multiple large erythrocyte aggregates completely covered the vessel wall and occupied >50% of the lumen in animals injected with uPA. Similar findings were observed in the rabbit femoral artery. (a)–(f) Sections of the rat carotid artery and (g)–(i) rabbit femoral artery 24 h post clot formation. Colors: blue, vessel walls; red, erythrocyte aggregates; green, red clot; white, white clot. Reproduced from [92], Copyright 2018, with the permission of IEEE. (C) The impact of thrombolytic drug on the stroke model induced by MNP@Thrombin was investigated. The changes in the infarction size with MNP or MNP@Thrombin after thrombolytic treatment were observed through TTC staining images. TTC staining, which can identify neuronal degradation, was employed to detect any pathological alterations after stroke. The use of U.K. led to a decrease in stroke lesions’ sizes and reduced neuronal degradation. These results were in line with the clinical scenario. Reproduced from [99], Copyright 2021, with the permission of IEEE. (D) The study aimed to investigate the dual targeting of Fe₃O₄-(4-PLA(G₃)₄)-RGD/nattokinase nanoparticles in male rats using RGD and magnetic targeting. After inducing thrombi formation, the rats were administered with 500 μL of PBS or PBS with either nattokinase or Fe₃O₄-(4-PLA(G₃)₄)-RGD/nattokinase through the tail vein. Frozen sections of the thrombi were observed and labeled as 1, with the Fe₃O₄-(4-PLA(G₃)₄)-RGD/nattokinase nanoparticles marked in a red circle. Hematoxylin and eosin staining of the experimental vessels was also performed and labeled as 2, after intravenous injection of PBS, PBS with nattokinase, PBS with Fe₃O₄-(4-PLA(G₃)₄)-RGD/nattokinase, and PBS with Fe₃O₄-(4-PLA(G₃)₄)-RGD/nattokinase under an external magnet. Reproduced from [95], Copyright 2020, with the permission of IEEE.

FIGURE 7.

In-vitro thrombolysis with magnetic nanoparticles in a dynamic magnetic field. (A) During treatments with (a) free tPA and (b) tPA-NCs, representative intravital microscopy pictures of the mesentery vasculature were acquired at various times. Reproduced from [114], Copyright 2015, with the permission of IEEE. (B) BMMs provided a platform for microvascular thrombolysis that was extremely minimally invasive. BMM swarm is propelled toward a blood clot in an artificial glass vein. The tPA-loaded BMMs were activated to collectively target and concentrate at the site of the blood clot in artificial vasculature using a rotating magnetic field. Scale bar: 300 μm. Reproduced from [116], Copyright 2020, with the permission of IEEE. (C) A platelet-rich thrombus was treated in a microfluidic model of hemostasis by tPA-wheels. After the horizontal channel coated with collagen-mimetic peptides and tissue factor is occluded by the thrombus, μwheels are introduced from the left vertical channel while blood is present in the right vertical channel. a, b, and c show brightfield images of μwheels accumulating at and penetrating into the thrombus. d to f shows epifluorescence of fibrin(ogen), while g to i shows epifluorescence of platelets. Reproduced from [118], Copyright 2017, with the permission of IEEE. (D) (a) These image sequences demonstrate a thrombus removal process that was solely mediated by urokinase. The moving boundary of the thrombus indicates that the thrombus was gradually eliminated by the diffusion of the injected urokinase. The average speed of the boundary movement was approximately 20 μm/min. (b) The image sequences depict the process of thrombus removal using RMF-guided Fe₃O₄ NPs. In the experiment, urokinase at a concentration of 50 μg/mL and NPs at a concentration of 10 mg/mL were used, and the interval between images was 102 s. At the start of the experiment (0 s), the NPs were seen to cluster into a microrod with a length of about 150 μm under the influence of the static magnetic field. The microrod then began to rotate with an angular velocity of ω, generated by the RMF. This rotation produced a vortex, which enhanced the diffusion of urokinase to the surface of the thrombus and accelerated its dissolution. Although the cohesive force of the aggregate was not strong enough, causing it to fragment into two parts at times (as shown in the images at 20 s and 80 s), the phenomenon of enhanced diffusion of urokinase continued, and the 2 mg thrombus was ablated in about 102 s. The thrombolysis speed was approximately 36 μm/min, which is 1.8 times faster than using the same dose of pure urokinase alone. Reproduced from [55], Copyright 2018, with the permission of IEEE.

FIGURE 8.

In-vivo thrombolysis with magnetic nanoparticles in a dynamic magnetic field. (A) Active nanomotors were used to enhance thrombolysis in a mice embolism model. (a) The experimental setup involved injecting different treatments into the right femoral vessels of C57/BL6 mice and inducing a rotating magnetic field (20 Hz, 40 mT) on the infected hindlimb for 45 minutes. (b) After 24 hours, the mice were anesthetized to check for previously formed thrombi in the femoral vessel. Three groups of mice were used, where Group I was treated with PBS, Group II was injected with t-PA solution, and Group III was treated with both t-PA and nickel rods. The results showed that thrombus remained in all mice of Group I, while Group II mice had a little residual thrombus. However, Group III mice, treated with both t-PA and Ni nanorods and subjected to the rotating magnetic field, had no residual thrombus left. Reproduced from [126], Copyright 2014, with the permission of IEEE. (B) In vivo fluorescence images of rats receiving different treatments are shown. Groups III and IV exhibited higher fluorescence intensity at the femoral vein site compared to groups I and II. This suggests that the system was successfully enriched at a specific site with the assistance of a magnet. Reproduced from [127], Copyright 2021, with the permission of IEEE. (C) Representative images of thrombolysis in dMCAO mice under different treatments. (a) As expected, no thrombolysis was observed in the control group treated with normal saline (NS) within 120 minutes. (b) When tPA was administered at a dose of 10 mg/kg, the blood clot was partially lysed and small arteries were reoccluded, resulting in incomplete recanalization within 85 minutes. (c) In contrast, MRs were able to rapidly target the blood clot with the guidance of magnets, but they could not achieve complete recanalization within 120 minutes. (d) However, when tPA-MRs (1 mg/kg; equivalent to 0.13 mg/kg tPA) were administered after dMCAO and under the influence of a rotational magnetic field (RMF, 20 Hz, 40 mT), the blood flow was restored in just 25 minutes, with no occlusion observed in the distal bifurcation. Reproduced from [128], Copyright 2018, with the permission of IEEE. (D) The thrombus images were captured and the changes in the thrombus were measured using ultrasound imaging every 30 minutes for a total of 90 minutes for various treatments. When the carotid artery was obstructed by a thrombus, the injected tPA solution flowed out through the collateral. Microscopic examination did not show any significant change in the thrombus after native tPA solution treatment. However, after 30 minutes of treatment, the signal of the thrombus area in the sagittal ultrasound image weakened, indicating gradual thrombolysis over time. After 90 minutes of treatment, the length of the thrombus decreased but did not dissolve completely, as shown by the filled thrombus signals in the vascular system from the cross-sectional ultrasound image. Combination treatment involved injecting an equivalent amount of tPA solution and magnetic nanoparticles, followed by guided diffusion to the thrombus through rotating locomotion. The thrombus length decreased gradually over time. Notably, the sagittal and cross-sectional ultrasound images revealed an opening at the embolic site at 60 minutes, suggesting recanalization of the blocked blood vessel. The recanalization area further increased at 90 minutes, and a clear passage was formed, as shown in the sagittal ultrasound image. Reproduced from [129], Copyright 2021, with the permission of IEEE.