A Comparison of Focused and Unfocused Ultrasound for Microbubble-Mediated Gene Delivery

Enhancing the therapeutic efficacy of gefitinib on subcutaneously transplanted SKOV3 ovarian cancer tumors in nude mice via ultrasound‑stimulated microbubble cavitation

The present study aimed to explore the effect of ultrasound-stimulated microbubble cavitation (USMC) on drug concentration and therapeutic efficacy of oral gefitinib in treating subcutaneously transplanted SKOV3 ovarian cancer tumors in nude mice. The present study employed the VINNO70 ultrasonic diagnostic and treatment integrated machine for USMC therapy. Firstly, the mechanical index was set at 0.25, and the therapeutic efficacy of USMC treatment was assessed at intervals of 5, 10 and 20 min. Briefly, 72 nude mice were randomized into the following four groups (n=18/group): Control group, USMC5 min group, USMC10 min group and USMC20 min group, and the therapeutic response to USMC treatment was evaluated by comparing pre-and post-intervention effects. Additionally, the combined therapeutic efficacy of USMC and gefitinib was investigated by randomly dividing 96 tumor-bearing mice into the following four groups (n=24/group): Control group, USMC group, gefitinib group and USMC + gefitinib group. Contrast-enhanced ultrasound, hematoxylin and eosin staining, western blotting, immunofluorescence staining, TUNEL staining, ELISA and liquid chromatography-mass spectrometry were performed in the present study. The results showed that USMC combined with gefitinib had the best treatment effect; the tumor inhibition rate was higher than that of gefitinib alone and the overall survival time was prolonged. In addition, the drug concentration in the tumor tissue obtained from the USMC + gefitinib group was revealed to be ~1.4 times higher than that detected in the group treated with gefitinib alone. The experimental results also confirmed that the strongest tumor inhibition rate and longest overall survival time was observed in the USMC + gefitinib group, followed by the gefitinib group and USMC group. STAT3 is an important signaling transducer and transcription factor, which, when phosphorylated, can lead to abnormal cell proliferation and malignant transformation. In addition, the upregulation of phosphorylated (p)-STAT3 is consider a reason for the poor efficacy of gefitinib in treating ovarian cancer. The present study revealed that ultrasound microbubble therapy could overcome this side effect. In conclusion, USMC improved the effects of oral gefitinib on subcutaneously transplanted SKOV3 ovarian cancer tumors in nude mice and increased drug penetration. In addition, USMC overcame the gefitinib-induced side effect of upregulated STAT3 phosphorylation and reduced the expression levels of p-STAT3 in the tumor.

Fabrication of porous poly(L-lactide-co-ε-caprolactone) micropowder for microbubble effect and ultrasound-mediated drug delivery

Biodegradable elastic poly(L-lactide-co-ε-caprolactone) (PLCL) copolymer (50:50, lactide:caprolactone molar ratio) was synthesized and porous PLCL micropowders was fabricated by a simple method involving rapid cooling of 0.1, 0.5, and 1% (wt/vol) PLCL/dioxane spray into liquid nitrogen. The physicochemical properties of the porous PLCL micropowders were examined by measuring their pore size, pore morphology, and microbead size using a scanning electron microscopy (SEM) and dye and temozolomide (TMZ)-release testing under ultrasound. Human U-87MG, glioblastoma (GBM) cell culture tests were performed to evaluate cell cytotoxicity by released drug from PLCL micropowders. In this study, the porous PLCL micropowders prepared from 1 wt%/vol% PLCL solutions showed a highly porous structure, satisfactory mechanical properties, and optimal drug release efficiency compared with those produced from 0.1 or 0.5 wt%/vol% solutions. The results of the accumulated release test with the results of the absorbance of the dye initially applied, it was confirmed that more than 80% of the added dye was trapped inside the micropowder, and clearly GBM cytotoxicity effect could be observed by the released TMZ. The drug release system using micropowders and ultrasound can be applied as a drug supply system for various diseases such as brain tumors with low drug permeability.

Non-Invasive Brain Sensing Technologies for Modulation of Neurological Disorders

The non-invasive brain sensing modulation technology field is experiencing rapid development, with new techniques constantly emerging. This study delves into the field of non-invasive brain neuromodulation, a safer and potentially effective approach for treating a spectrum of neurological and psychiatric disorders. Unlike traditional deep brain stimulation (DBS) surgery, non-invasive techniques employ ultrasound, electrical currents, and electromagnetic field stimulation to stimulate the brain from outside the skull, thereby eliminating surgery risks and enhancing patient comfort. This study explores the mechanisms of various modalities, including transcranial direct current stimulation (tDCS) and transcranial magnetic stimulation (TMS), highlighting their potential to address chronic pain, anxiety, Parkinson's disease, and depression. We also probe into the concept of closed-loop neuromodulation, which personalizes stimulation based on real-time brain activity. While we acknowledge the limitations of current technologies, our study concludes by proposing future research avenues to advance this rapidly evolving field with its immense potential to revolutionize neurological and psychiatric care and lay the foundation for the continuing advancement of innovative non-invasive brain sensing technologies.

Sono-activated materials for enhancing focused ultrasound ablation: Design and application in biomedicine

The ablation effect of focused ultrasound (FUS) has played an increasingly important role in the biomedical field over the past decades, and its non-invasive features have great advantages, especially for clinical diseases where surgical treatment is not available or appropriate. Recently, rapid advances in the adjustable morphology, enzyme-mimetic activity, and biostability of sono-activated materials have significantly promoted the medical application of FUS ablation. However, a systematic review of sono-activated materials based on FUS ablation is not yet available. This progress review focuses on the recent design, fundamental principles, and applications of sono-activated materials in the FUS ablation biomedical field. First, the different ablation mechanisms and the key factors affecting ablation are carefully determined. Then, the design of sono-activated materials with high FUS ablation efficiencies is comprehensively discussed. Subsequently, the representative biological applications are summarized in detail. Finally, the primary challenges and future perspectives are also outlined. We believe this timely review will provide key information and insights for further exploration of focused ultrasound ablation and new inspiration for designing future sono-activated materials. STATEMENT OF SIGNIFICANCE: The ablation effect of focused ultrasound (FUS) has played an increasingly important role in the biomedical field over the past decades. However, there are also some challenges of FUS ablation, such as skin burns, tumour recurrence after thermal ablation, and difficulty in controlling cavitation ablation. The rapid advance in adjustable morphology, enzyme-mimetic activity, and biostability of sono-activated materials has significantly promoted the medical application of FUS ablation. However, the systematic review of sono-activated materials based on FUS ablation is not yet available. This progress review focuses on the recent design, fundamental principles, and applications in the FUS ablation biomedical field of sono-activated materials. We believe this timely review will provide key information and insights for further exploration of FUS ablation.

Nanotargeted Cationic Lipid Microbubbles Carrying HSV-TK Gene Inhibit the Development of Subcutaneous Liver Tumor Model After HIFU Ablation

OBJECTIVES

High-intensity focused ultrasound (HIFU) has been widely used in clinical settings and has achieved suitable results in the treatment of many cancerous or noncancerous diseases. However, in the treatment of liver cancer, because the tumor is located deep within the liver tissue, when ultrasound penetrates the tissue, it will inevitably produce sound energy attenuation. This attenuation limits the reliability of HIFU treatment, reduce the efficacy of HIFU, and increase the risk of tumor recurrence.

METHODS

Cationic microbubbles (CMB) were successfully linked with GPC3 and HSV-TK plasmids, and targeted gene-carrying CMB were successfully constructed. Moreover, the gene-targeted cation microbubbles had suitable targeting and can specifically bind with liver cancer cells.

RESULTS

The HSV-TK transfection efficiency was high and had a significant inhibitory effect on the proliferation and invasion of liver cancer cells. After the gene-carrying cation microbubbles entered the animal body, they had a great targeting effect in vivo. They transfected the target genes into liver cancer cells, and the HSV-TK/GCV system initiated cell death, demonstrating that these targeted microbubbles, enhanced HIFU treatment.

CONCLUSIONS

Overall, CMB combined with a GPC3 antibody and HSV-TK plasmid can target residual subcutaneous liver tumor cells under the guidance of GPC3 antibody, and kill residual subcutaneous liver tumor cells under the action of ultrasound, thus enhancing the therapeutic effect of HIFU on liver cancer.

Microbubble-assisted ultrasound for inner ear drug delivery

Treating pathologies of the inner ear is a major challenge. To date, a wide range of procedures exists for administering therapeutic agents to the inner ear, with varying degrees of success. The key is to deliver therapeutics in a way that is minimally invasive, effective, long-lasting, and without adverse effects on vestibular and cochlear function. Microbubble-assisted ultrasound ("sonoporation") is a promising new modality that can be adapted to the inner ear. Combining ultrasound technology with microbubbles in the middle ear can increase the permeability of the round window, enabling therapeutic agents to be delivered safely and effectively to the inner ear in a targeted manner. As such, sonoporation is a promising new approach to treat hearing loss and vertigo. This review summarizes all studies on the delivery of therapeutic molecules to the inner ear using sonoporation.

Non-viral in vivo cytidine base editing in hepatocytes using focused ultrasound targeted microbubbles

CRISPR-Cas9-based genome editing technologies, such as base editing, have the potential for clinical translation, but delivering nucleic acids into target cells in vivo is a major obstacle. Viral vectors are widely used but come with safety concerns, while current non-viral methods are limited by low transfection efficiency. Here we describe a new method to deliver CRISPR-Cas9 base editing vectors to the mouse liver using focused ultrasound targeted microbubble destruction (FUTMD). We demonstrate, using the example of cytosine base editing of the Pde3b gene, that FUTMD-mediated delivery of cytosine base editing vectors can introduce stop codons (up to ∼2.5% on-target editing) in mouse liver cells in vivo. However, base editing specificity is less than one might hope with these DNA constructs. Our findings suggest that FUTMD-based gene editing tools can be rapidly and transiently deployed to specific organs and sites, providing a powerful platform for the development of non-viral genome editing therapies. Non-viral delivery also reveals greater off-target base exchange in vivo than in vitro.

Simple sacrificial-layer-free microfabrication processes for air-cavity Fresnel acoustic lenses (ACFALs) with improved focusing performance

Focused ultrasound (FUS) is a powerful tool widely used in biomedical therapy and imaging as well as in sensors and actuators. Conventional focusing techniques based on curved surfaces, metamaterial structures, and multielement phased arrays either present difficulties in massively parallel manufacturing with high precision or require complex drive electronics to operate. These difficulties have been addressed by microfabricated self-focusing acoustic transducers (SFATs) with Parylene air-cavity Fresnel acoustic lenses (ACFALs), which require a time-demanding step in removing the sacrificial layer. This paper presents three new and improved types of ACFALs based on polydimethylsiloxane (PDMS), an SU-8/PDMS bilayer, and SU-8, which are manufactured through simple sacrificial-layer-free microfabrication processes that are two to four times faster than that for the Parylene ACFALs. Moreover, by studying the effect of the lens thickness on the acoustic transmittance through the lens, the performance of the transducers has been optimized with improved thickness control techniques developed for PDMS and SU-8. As a result, the measured power transfer efficiency (PTE) and peak output acoustic pressure are up to 2.0 and 1.8 times higher than those of the Parylene ACFALs, respectively. The simple microfabrication techniques described in this paper are useful for manufacturing not only high-performance ACFALs but also other miniaturized devices with hollow or suspended structures for microfluidic and optical applications.

The Significance of PAX8-PPARγ Expression in Thyroid Cancer and the Application of a PAX8-PPARγ-Targeted Ultrasound Contrast Agent in the Early Diagnosis of Thyroid Cancer

Objective. To investigate the significance of PAX8-PPARγ expression in thyroid cancer and the application of a PAX8-PPARγ-targeted ultrasound contrast agent in the early diagnosis of thyroid cancer. Methods. In this study, the expression of PAX8-PPARγ in thyroid cancer tissues, paracancer groups, and normal thyroid tissues was detected by western and immunohistochemical techniques; the effects of PAX8-PPARγ expression inhibition on thyroid cancer cell growth, clonogenic ability, and antiapoptosis were examined. The terminal carboxylactic acid/hydroxyacetic acid copolymer (PLGA-COOH) nanoparticles were prepared by the double emulsification solvent volatilization method. The in vitro cytotoxicity of the targeted contrast agent was detected by MTS and other methods; LD50 was used to evaluate its short-term in vivo toxicity after intraperitoneal injection in mice. Results. PAX8-PPARγ expression was significantly increased in thyroid cancer tissues, and the expression level of PAX8-PPARγ was closely correlated with TNM staging and lymph node metastasis ( $P$  < 0.05). In addition, PAX8-PPARγ was also expressed at high levels in thyroid cancer cell lines relative to normal thyroid cells. MTS experiments showed that the PAX8-PPARγ-targeted ultrasound nanocontrast agent had no significant toxic side effects on thyroid cells; countess observed that the contrast agent had no effect on cell survival and mortality; the LD50 assay showed that the targeted contrast agent had a wide safety range. Western blot showed the expression of caspase-3, BAX, and Bcl-2 in thyroid cancer cells, indicating that the nanocontrast agent has a good biosafety. In vitro targeting experiments showed that there were more nanospheres aggregated around the cells in the targeted contrast group. In vivo targeting imaging of nude mice revealed that the ultrasound signal was significantly enhanced in the targeted group compared with the nontargeted group after 20 min of LIFU irradiation. Conclusion. PAX8-PPARγ overexpression in thyroid cancer cell lines and thyroid cancer tissues promoted the proliferation and antiapoptotic ability of thyroid cancer cells and promoted the tumorigenic ability in nude mice in vivo. We successfully prepared a PAX8-PPARγ-targeted ultrasound nanocontrast agent, which has regular morphology, uniform size, and high stability, and its liquid-gas phase change can be promoted at lower temperature. Therefore, this contrast agent can achieve US-targeted imaging and temperature phase transition function, and may have enhanced ultrasound imaging potential.

Ultrasound-mediated gene delivery of factor VIII plasmids for hemophilia A gene therapy in mice

Gene therapy offers great promises for a cure of hemophilia A resulting from factor VIII (FVIII) gene deficiency. We have developed and optimized a non-viral ultrasound-mediated gene delivery (UMGD) strategy. UMGD of reporter plasmids targeting mice livers achieved high levels of transgene expression predominantly in hepatocytes. Following UMGD of a plasmid encoding human FVIII driven by a hepatocyte-specific promoter/enhancer (pHP-hF8/N6) into the livers of hemophilia A mice, a partial phenotypic correction was achieved in treated mice. In order to achieve persistent and therapeutic FVIII gene expression, we adopted a plasmid (pHP-hF8-X10) encoding an FVIII variant with significantly increased FVIII secretion. By employing an optimized pulse-train ultrasound condition and immunomodulation, the treated hemophilia A mice achieved 25%–150% of FVIII gene expression on days 1–7 with very mild transient liver damage, as indicated by a small increase of transaminase levels that returned to normal within 3 days. Therapeutic levels of FVIII can be maintained persistently without the generation of inhibitors in mice. These results indicate that UMGD can significantly enhance the efficiency of plasmid DNA transfer into the liver. They also demonstrate the potential of this novel technology to safely and effectively treat hemophilia A.

Effect of Gambogic Acid-Loaded Porous-Lipid/PLGA Microbubbles in Combination With Ultrasound-Triggered Microbubble Destruction on Human Glioma

Gambogic acid (GA) is a highly effective antitumor agent, and it is used for the treatment of a wide range of cancers. It is challenging to deliver drugs to the central nervous system due to the inability of GA to cross the blood-brain barrier (BBB). Studies have shown that ultrasound-targeted microbubble destruction can be used for transient and reversible BBB disruption, significantly facilitating intracerebral drug delivery. We first prepared GA-loaded porous-lipid microbubbles (GA porous-lipid/PLGA MBs), and an in vitro BBB model was established. The cell viability was detected by CCK-8 assay and flow cytometry. The results indicate that U251 human glioma cells were killed by focused ultrasound (FUS) combined with GA/PLGA microbubbles. FUS combined with GA/PLGA microbubbles was capable of locally and transiently enhancing the permeability of BBB under certain conditions. This conformational change allows the release of GA to extracellular space. This study provides novel targets for the treatment of glioma.

Ultrasound-Enabled Therapeutic Delivery and Regenerative Medicine: Physical and Biological Perspectives

The role of ultrasound in medicine and biological sciences is expanding rapidly beyond its use in conventional diagnostic imaging. Numerous studies have reported the effects of ultrasound on cellular and tissue physiology. Advances in instrumentation and electronics have enabled successful in vivo applications of therapeutic ultrasound. Despite path breaking advances in understanding the biophysical and biological mechanisms at both microscopic and macroscopic scales, there remain substantial gaps. With the progression of research in this area, it is important to take stock of the current understanding of the field and to highlight important areas for future work. We present herein key developments in the biological applications of ultrasound especially in the context of nanoparticle delivery, drug delivery, and regenerative medicine. We conclude with a brief perspective on the current promise, limitations, and future directions for interfacing ultrasound technology with biological systems, which could provide guidance for future investigations in this interdisciplinary area.