Unilateral Opening of Rat Blood-Brain Barrier Assisted by Diagnostic Ultrasound Targeted Microbubbles Destruction

A One-Stone-Two-Birds Strategy of Targeting Microbubbles with "Dual" Anti-Inflammatory and Blood-Brain Barrier "Switch" Function for Ischemic Stroke Treatment

Inflammation is considered to be the main target of the development of new stroke therapies. There are three key issues in the treatment of stroke inflammation: the first one is how to overcome the blood-brain barrier (BBB) to achieve drug delivery, the second one is how to select drugs to treat stroke inflammation, and the third one is how to achieve targeted drug delivery. In this study, we constructed hydrocortisone-phosphatidylserine microbubbles and combined them with ultrasound (US)-targeted microbubble destruction technology to successfully open the BBB to achieve targeted drug delivery. Phosphatidylserine on the microbubbles was used for its "eat me" effect to increase the targeting of the microvesicles. In addition, we found that hydrocortisone can accelerate the closure of the BBB, achieving efficient drug delivery while reducing the entry of peripheral toxins into the brain. In the treatment of stroke inflammation, it was found that hydrocortisone itself has anti-inflammatory effects and can also change the polarization of microglia from the harmful pro-inflammatory M1 phenotype to the beneficial anti-inflammatory M2 phenotype, thus achieving dual anti-inflammatory effects and enhancing the anti-inflammatory effects in ischemic areas after stroke, well reducing the cerebellar infarction volume by inhibiting the inflammatory response after cerebral ischemia. A confocal microendoscope was used to directly observe the polarization of microglial cells in living animal models for dynamic microscopic visualization detection showing the advantage of being closer to clinical work. Taken together, this study constructed a multifunctional targeted US contrast agent with the function of "one-stone-two-birds", which can not only "on-off" the BBB but also have "two" anti-inflammatory functions, providing a new strategy of integrated anti-inflammatory targeted delivery and imaging monitoring for ischemic stroke treatment.

Ultrasound targeted microbubble destruction assists dual delivery of beta-amyloid antibody and neural stem cells to restore neural function in transgenic mice of Alzheimer's disease

OBJECTIVES

To explore the feasibility, efficacy and safety of ultrasound targeted microbubbles destruction (UTMD) assisted dual delivery of beta-amyloid (Aβ) antibody loaded by microbubbles (MB_Aβ ) and neural stem cells (NSCs) on Alzheimer's disease (AD).

METHODS

27 APP/PS1 double transgenic mice (Tg mice) and 33 wild-type mice were used. Wild-type mice were insonated by diagnostic ultrasound with microbubbles (MB) for 5 min to observe the blood brain barrier (BBB) opening. The survival situation of engrafted NSCs crossing the opened BBB mediated by UTMD in AD mice was evaluated by in vivo imaging system. We further explored the combination therapy of UTMD mediated Aβ antibody and NSCs dual delivery. Tg mice in each group were exposed to diagnostic ultrasound for 5 min once a week for four times, with MB, MB_Aβ , and/or NSCs administration. Cognition and memory functions were explored by Morris water maze test, Aβ plaques deposition was evaluated by immunohistochemical, and brain-derived neurotrophic factor (BDNF) and synaptophysin (SYN) expression were detected by western blot and immunofluorescence.

RESULTS

BBB was opened mediated by diagnostic ultrasound with MB and the duration of opening was about 10 h. The transplanted NSCs survived in Tg mice for no more than 72 h. Compared with control group, the mice in combined delivery of NSCs and Aβ antibody by UTMD group improved memory function and spatial learning with shorter latency to find the platform, longer distance traveled and longer time spent in targeted quadrant, and more crossing times (P < 0.05). Besides, the combination delivery group promoted the clearance of Aβ plaques compared with control group both in hippocampus (P < 0.01) and cortex (P < 0.05). Moreover, the expression of BDNF in combination delivery group was significantly higher than that in control group and US mediated MB group (P < 0.05). No significant change of SYN was observed in each group.

CONCLUSION

UTMD assisted dual delivery of Aβ antibody and NSCs to AD mice brain could help to clear Aβ plaques, increase the expression of BDNF and restore the impaired neural function. This finding may offer potential insight into treatment of AD. This article is protected by copyright. All rights reserved.

Phase-changeable nanoparticle-mediated energy conversion promotes highly efficient high-intensity focused ultrasound ablation

This review describes how phase-changeable nanoparticles enable highly efficient high-intensity focused ultrasound ablation (HIFU). HIFU is effective in the clinical treatment of solid malignant tumors. However, it has intrinsic disadvantages for treating some deep lesions, such as damage to surrounding normal tissues. When phase-changeable nanoparticles are used in HIFU treatment, they could serve as good synergistic agents because they are transported in the blood and permeated and accumulated effectively in tissues. HIFU's thermal effects can trigger nanoparticles to undergo a special phase transition, thus enhancing HIFU ablation efficiency. Nanoparticles can also carry anticancer agents and release them in the targeted area to achieve chemo-synergistic therapy response. Although the formation of nanoparticles is complicated and HIFU applications are still in an early stage, the potential for their use in synergy with HIFU treatment shows promising results.

Recent Advances on Ultrasound Contrast Agents for Blood-Brain Barrier Opening with Focused Ultrasound

The blood-brain barrier is the primary obstacle to efficient intracerebral drug delivery. Focused ultrasound, in conjunction with microbubbles, is a targeted and non-invasive way to disrupt the blood-brain barrier. Many commercially available ultrasound contrast agents and agents specifically designed for therapeutic purposes have been investigated in ultrasound-mediated blood-brain barrier opening studies. The new generation of sono-sensitive agents, such as liquid-core droplets, can also potentially disrupt the blood-brain barrier after their ultrasound-induced vaporization. In this review, we describe the different compositions of agents used for ultrasound-mediated blood-brain barrier opening in recent studies, and we discuss the challenges of the past five years related to the optimal formulation of agents.

Electroacupuncture: a new approach to open the blood-brain barrier in rats recovering from middle cerebral artery occlusion

Objective

To examine for an opening effect on the blood–brain barrier (BBB) in intact rats and rats with experimental ischaemia-reperfusion (I/R) during the recovery period after various electroacupuncture (EA) treatments with different time courses, and to determine whether there is a time-dependent effect. An additional objective was to determine whether this method could induce the penetration of nerve growth factor (NGF) through the BBB.

Methods

A middle cerebral artery occlusion (MCAO) model was first established. We chose different stimulation time courses and observed the effects of EA treatment (100 Hz frequency; 2 mA intensity) at GV20 and GV26 on the BBB in rats recovering from MCAO 3 weeks after modelling. The rats were injected with 2% Evans blue (EB) saline. The brain water content was measured using a wet/dry weighing method. The degree of penetration of EB was detected using spectrophotometry and laser confocal microscopy. The rats were then injected with NGF, and the concentration of NGF in the brain tissues was measured using ELISA.

Results

The increase in the BBB permeability was most notable following the 8 min EA stimulation (P<0.05), which may be advantageous for the targeted delivery of drugs (such as NGF) into the brain. Additionally, this effect did not appear to cause brain oedema (P>0.05) in healthy or MCAO rats.

Conclusions

EA treatment for a certain stimulation time at GV20 and GV26 in MCAO rats can increase BBB permeability.