Ultrasound-mediated blood-brain barrier opening: An effective drug delivery system for theranostics of brain diseases

Imaging probes for the detection of brain microenvironment

The brain microenvironment (BME) is a highly dynamic system that plays a critical role in neural excitation, signal transmission, development, aging, and neurological disorders. BME consists of three key components: neural cells, extracellular spaces, and physical fields, which provide structures and physicochemical properties to synergistically and antagonistically regulate cell behaviors and functions such as nutrient transport, waste metabolism and intercellular communication. Consequently, monitoring the BME is vital to acquire a better understanding of the maintenance of neural homeostasis and the mechanisms underlying neurological diseases. In recent years, researchers have developed a range of imaging probes designed to detect changes in the microenvironment, enabling precise measurements of structural and biophysical parameters in the brain. This advancement aids in the development of improved diagnostic and therapeutic strategies for brain disorders and in the exploration of cutting-edge mechanisms in neuroscience. This review summarizes and highlights recent advances in the probes for sensing and imaging BME. Also, we discuss the design principles, types, applications, challenges, and future directions of probes.

Ultrasound-Assisted Blood-Brain Barrier Opening Monitoring by Photoacoustic and Fluorescence Imaging Using Indocyanine Green

OBJECTIVE

The blood-brain barrier (BBB) is a selectively permeable membrane that restricts drug delivery to the central nervous system. Focused ultrasound (FUS) combined with microbubbles (MBs) is a promising technique to transiently open the BBB, enabling therapeutic delivery. However, real-time monitoring of BBB permeability changes remains challenging. This study investigated the use of indocyanine green (ICG) as a bi-modal contrast agent for photoacoustic and fluorescence imaging to assess BBB opening and closure dynamics.

METHODS

BALB/c mice underwent FUS-mediated BBB opening with different doses of MBs and ICG administration. Photoacoustic and fluorescence imaging were performed at various time points post-FUS to evaluate ICG extravasation dynamics. Magnetic resonance imaging (MRI) with gadolinium contrast was used as the gold standard for BBB permeability assessment. The effect of MB dose and injection timing on BBB closure kinetics was analyzed.

RESULTS

Photoacoustic imaging provided reliable BBB monitoring within the first hour post-FUS, whereas fluorescence imaging was more effective at detecting ICG extravasation at 24 h. A strong correlation was observed between fluorescence intensity and MRI-based contrast enhancement, confirming BBB opening dynamics. BBB closure followed an exponential decay model, with a half-closure time of approximately 81 min. The degree of BBB opening was proportional to the MB dose administered.

CONCLUSION

ICG-based photoacoustic and fluorescence imaging provide a non-invasive and cost-effective alternative to MRI for monitoring FUS-induced BBB opening. These techniques offer complementary temporal windows for assessment, improving the precision of BBB permeability evaluation in preclinical and potentially clinical applications.

Transcriptomic Alterations in the Hippocampus and Prefrontal Cortex of Rats with Chronic Unpredictable Stress Induced by Low-Intensity Pulsed Ultrasound

In our previous study, low-intensity pulsed ultrasound stimulation (LIPUS), a novel noninvasive neuromodulation tool, effectively alleviated depression-like behaviors in a rat model of depression. However, the underlying mechanisms remain unclear. The present study aimed to elucidate the relevant mechanisms through transcriptomic research. To induce depression-like phenotypes, rats were subjected to chronic unpredictable stress (CUS) for six weeks. Following this initial stress period, LIPUS was administered daily for an additional four weeks while the rats were continuously exposed to CUS, which was previously determined to significantly reduce immobility time in forced swimming test. The transcriptome expression profiles in the hippocampus and prefrontal cortex (PFC) were subsequently analyzed by RNA sequencing techniques. Overall, LIPUS reversed the abnormal expression of genes in the brain of model rats, especially the expression of genes linked to glucose and lipid metabolism. Specifically, we found that the CUS rats exhibited 3464 differentially expressed genes (DEGs) in the hippocampus and 1781 DEGs in the PFC compared to the control group. LIPUS reversed the expression of 592 genes in the hippocampus and 254 genes in the PFC. Functional analysis revealed a significant enrichment of DEGs related to oxygen carrier activity and sugar metabolism. Subsequently, the alterations in the top ten genes were validated using real-time PCR. The significant changes in the expression of hemoglobin subunit beta, growth hormone 1, and glucokinase were confirmed. The results suggest that LIPUS may alleviate depression-related manifestations by regulating cerebral oxygenation and sugar metabolism processes in the brain.

Nanomaterials-driven in situ vaccination: a novel frontier in tumor immunotherapy

In situ vaccination (ISV) has emerged as a promising strategy in cancer immunotherapy, offering a targeted approach that uses the tumor microenvironment (TME) to stimulate an immune response directly at the tumor site. This method minimizes systemic exposure while maintaining therapeutic efficacy and enhancing safety. Recent advances in nanotechnology have enabled new approaches to ISV by utilizing nanomaterials with unique properties, including enhanced permeability, retention, and controlled drug release. ISV employing nanomaterials can induce immunogenic cell death and reverse the immunosuppressive and hypoxic TME, thereby converting a "cold" tumor into a "hot" tumor and facilitating a more robust immune response. This review examines the mechanisms through which nanomaterials-based ISV enhances anti-tumor immunity, summarizes clinical applications of these strategies, and evaluates its capacity to serve as a neoadjuvant therapy for eliminating micrometastases in early-stage cancer patients. Challenges associated with the clinical translation of nanomaterials-based ISV, including nanomaterial metabolism, optimization of treatment protocols, and integration with other therapies such as radiotherapy, chemotherapy, and photothermal therapy, are also discussed. Advances in nanotechnology and immunotherapy continue to expand the possible applications of ISV, potentially leading to improved outcomes across a broad range of cancer types.

Ultrasonic head-mounted device spatiotemporal opening blood-brain barrier enhances the brain permeation of drugs for treatment of radiation-induced brain injury

The field of physical therapy is advancing and using focused ultrasound to deliver drugs into the brain gains growing interest. However, the blood-brain barrier makes it difficult for drugs to enter. Finding safe and efficient physical therapy strategies to complement drug treatments is essential. Here, the rule and molecular mechanisms of spatiotemporal opening blood-brain barrier of ultrasound were explored using a Bluetooth-controlled ultrasonic head-mounted device which was used to enhance the brain permeation of drugs for the treatment of radiation-induced brain injury. The falling-off of tight junction proteins in the blood-brain barrier was the key to spatiotemporally opening under ultrasound. Evans blue and Rhodamine B represented macromolecules and small molecules, respectively, which were intravenously injected into the circulation. Their brain permeation was promoted by brain ultrasound and the smaller molecules required the lower sound intensity that also affected the speed of drug-passing. During the blood-brain barrier restoration after ultrasound, biomarkers like enzymes and growth factors changed, which could be used for selection of dosing window. After the use of the helmet, the blood-brain barrier was restored after 24 h, and the efficacy of water-soluble drugs for the treatment of radiation brain injury was increased. It was suitable for non-invasive external use and enhanced the treating effect when cooperating with drugs. This study provides a research basis for applying ultrasound technology into physio-pharmacotherapy.

Applications of Matrix Metalloproteinase-9-Related Nanomedicines in Tumors and Vascular Diseases

Matrix metalloproteinase-9 (MMP-9) is implicated in tumor progression and vascular diseases, contributing to angiogenesis, metastasis, and extracellular matrix degradation. This review comprehensively examines the relationship between MMP-9 and these pathologies, exploring the underlying molecular mechanisms and signaling pathways involved. Specifically, we discuss the contribution of MMP-9 to tumor epithelial-mesenchymal transition, angiogenesis, and metastasis, as well as its involvement in a spectrum of vascular diseases, including macrovascular, cerebrovascular, and ocular vascular diseases. This review focuses on recent advances in MMP-9-targeted nanomedicine strategies, highlighting the design and application of responsive nanoparticles for enhanced drug delivery. These nanotherapeutic strategies leverage MMP-9 overexpression to achieve targeted drug release, improved tumor penetration, and reduced systemic toxicity. We explore various nanoparticle platforms, such as liposomes and polymer nanoparticles, and discuss their mechanisms of action, including degradation, drug release, and targeting specificity. Finally, we address the challenges posed by the heterogeneity of MMP-9 expression and their implications for personalized therapies. Ultimately, this review underscores the diagnostic and therapeutic potential of MMP-9-targeted nanomedicines against tumors and vascular diseases.

Utilization of nanotechnology to surmount the blood-brain barrier in disorders of the central nervous system

Central nervous system (CNS) diseases are a major cause of disability and death worldwide. Due to the blood-brain barrier (BBB), drug delivery for CNS diseases is extremely challenging. Nano-delivery systems can overcome the limitations of BBB to deliver drugs to the CNS, improve the ability of drugs to target the brain and provide potential therapeutic methods for CNS diseases. At the same time, the choice of different drug delivery methods (bypassing BBB or crossing BBB) can further optimize the therapeutic effect of the nano-drug delivery system. This article reviews the different methods of nano-delivery systems to overcome the way BBB enters the brain. Different kinds of nanoparticles to overcome BBB were discussed in depth.

Stimuli-responsive nanoscale drug delivery system for epilepsy theranostics

Epilepsy is a common neurological disease characterized by distinct pathological changes in the epileptogenic zone. Antiseizure drugs (ASDs) are widely used as the primary treatment for epilepsy. To improve the efficiency of ASDs medication, stimuli-responsive nanoscale drug delivery systems (nanoDDSs), triggered by either endogenous or exogenous factors, have been developed and been considered as a noninvasive and spatial-temporal approach to epilepsy theranostics. In this review, we introduce the pathological variations observed in epileptic lesions such as dysregulated neurotransmitter systems, disrupted ion homeostasis, and dynamic inflammatory cytokine networks. Furthermore, we summarize the recent advances in functional nano-assemblies that could be activated by endogenous stimuli of pathological alterations or exogenous stimuli such as electricity, light, and other interventions. Finally, we discuss the remaining challenges and prospect the insight into perspective of future development in this field. In summary, this review aims to highlight the potential of stimuli-responsive nanoDDSs as precise, controllable and efficient strategies for addressing unresolved issues in epilepsy theranostics. STATEMENT OF SIGNIFICANCE: This review summarizes recent progress in pathological changes such as dysregulated neurotransmitter system, disrupted ion homeostasis and dynamic inflammatory cytokine network, and emphasizes endogenous/exogenous stimuli-responsive nanoscale platforms including neurotransmitter-, ion-, and other stimuli-responsive nanoDDSs, providing the prospects of smart nanoDDSs applications and discussing the challenges to offer generalized guideline for further development of epilepsy theranostics.

Extracellular Vesicle-Associated Angiopoietin-2 and Cell Migration-Inducing Protein in Lung Cancer Progression and Brain Metastases

BACKGROUND

Angiopoietin-2 (ANGPT2) and cell migration-inducing protein (CEMIP) are key regulators of angiogenesis, extracellular matrix remodeling, and metastatic progression in various cancers, including lung cancer (LC). The presence of these biomarkers in extracellular vesicles (EVs) may offer valuable insights into the molecular mechanisms underlying LC progression and metastasis. Extracellular vesicles play a critical role in LC by enhancing intercellular communication and supporting processes such as angiogenesis, immune evasion, and metastasis, transferring key molecules like vascular endothelial growth factor (VEGF) and pro-angiogenic microRNAs (miRNAs).

METHODS

This study aimed to investigate the presence and quantification of ANGPT2 and CEMIP in the cargo of EVs isolated from plasma samples obtained from the peripheral venous blood of patients with localized lung cancer (LLC group), lung cancer with brain metastases (LCM group), and healthy controls (HC group). EVs were isolated using the density gradient ultracentrifugation method, and their characterization was performed through scanning and transmission electron microscopy as well as flow cytometry. Western blot analysis was used to identify ANGPT2 and CEMIP in EV cargo, and band intensity from western blot images was quantified using specialized software.

RESULTS

The expression of ANGPT2 and CEMIP in EV cargo was significantly higher in the oncologic groups (LLC and LCM combined) compared to the HC group. Notably, EV CEMIP levels were, on average, 59% higher in patients with brain metastases than in those with localized lung cancer. Following surgical resection, postoperative EV ANGPT2 and EV CEMIP levels decreased by 36% and 8.5%, respectively, in the LLC group, and by 40% and 4.6%, respectively, in the LCM group.

CONCLUSION

These findings emphasize the potential of ANGPT2 and CEMIP as biomarkers for LC progression and prognosis. To our knowledge, no previous study has evaluated the presence and quantification of ANGPT2 and CEMIP in EV cargo from lung cancer patients. To further validate their role in cancer progression, functional studies should explore the mechanistic effects of EV-associated ANGPT2 and CEMIP on angiogenesis, immune modulation, cell migration, extracellular matrix remodeling, and tumor progression in lung cancer models.

Vectors in CRISPR Gene Editing for Neurological Disorders: Challenges and Opportunities

Diseases of the nervous system are recognized as the second leading cause of death worldwide. The global prevalence of neurological diseases, such as Huntington's disease, Alzheimer's disease, and Parkinson's disease has seen a significant rise due to the increasing proportion of the aging population. The discovery of the clustered regularly interspaced short palindromic repeats (CRISPR) genome editing technique has paved way for universal neurological diseases treatment. However, finding a safe and effective method to deliver CRISPR gene-editing tools remains a main challenge for genome editing therapies in vivo. Adeno-associated virus (AAV) is currently one of the most commonly used vector systems, but some issues remain unresolved, including capsid immunogenicity, off-target mutations, and potential genotoxicity. To address these concerns, researchers are actively encouraging the development of new delivery systems, like virus-like particles and nanoparticles. These novel systems have the potential to enhance targeting efficiency, thereby offering possible solutions to the current challenges. This article reviews CRISPR delivery vectors for neurological disorders treatment and explores potential solutions to overcome limitations in vector systems. Additionally, the delivery strategies of CRISPR systems are highlighted as valuable tools for studying neurological diseases, and the challenges and opportunities that these vectors present.

Intracalvariosseous injection: an approach for central nervous system drug delivery through skull bone marrow with a preclinical research in stroke

BACKGROUND

Central nervous system (CNS) accessibility constitutes a major hurdle for drug development to treat neurological diseases. Existing drug delivery methods rely on breaking the blood-brain barrier (BBB) for drugs to penetrate the CNS. Researchers have discovered natural microchannels between the skull bone marrow and the dura mater, providing a pathway for drug delivery through the skull bone marrow. However, there has been no research on the feasibility, safety, and efficacy of this delivery method for drug treatment of stroke.

METHODS

We used a microporous method for intracalvariosseous (ICO) injection to deliver drugs directly into brain parenchyma through skull bone marrow. Safety of ICO was assessed by monitoring changes in skull and peripheral blood neutrophil counts, and FITC-dextran extravasation across the BBB. Drug delivery pathways were observed through transparent skull-dura mater-brain tissue. In a rodent stroke model, NA-1 or Y-3 neuroprotective agents were administered via ICO to evaluate safety and efficacy by assessing neurological deficits, infarct size, neuroinflammatory factors, neuronal apoptosis, and liver/kidney function. Drug concentration in tissues was measured using fluorescence tracing and high-performance liquid chromatography to gauge ICO delivery efficiency.

FINDINGS

ICO injection delivers drugs to the brain parenchyma through microchannels between the skull bone marrow and the dura mater, offering higher delivery efficiency than intravenous injection. After ICO injection, there were no changes in neutrophil counts in the skull bone marrow and peripheral blood, and the amount of FITC-dextran passing through the BBB remained unchanged. This confirmed that ICO injection does not cause skull infection or break BBB, which suggested ICO injection is safe and feasible. In the treatment of stroke with neuroprotective agents, although the drug dosage of ICO injection was lower than intravenous injection, drug accumulation in the brain increased after ICO injection, which helped repair nerve damage, reduce neuronal apoptosis, and decrease the expression of inflammatory factors.

INTERPRETATION

ICO injection is a central nervous system drug delivery method that utilizes natural microchannels between the skull and dura mater for efficient drug delivery. Our results assessed the feasibility and safety of ICO injection at the preclinical level and evaluated its efficacy in animal models of stroke. The findings provided a foundation for the clinical translation of ICO injection.

FUNDING

This study was supported by The National Natural Science Foundation of China (No. 82425101); Beijing Municipal Science & Technology Commission (No. Z231100004823036); Capital's Funds for Health Improvement and Research (2022-2-2045); National Key Research & Development Program of China (2022YFF1501500, 2022YFF1501501, 2022YFF1501502, 2022YFF1501503, 2022YFF1501504, 2022YFF1501505).

Present insights into the progress in gene therapy delivery systems for central nervous system diseases

Central nervous system (CNS) diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), spinal cord injury (SCI), and ischemic strokes and certain rare diseases, such as amyotrophic lateral sclerosis (ALS) and ataxia, present significant obstacles to treatment using conventional molecular pharmaceuticals. Gene therapy, with its ability to target previously "undruggable" proteins with high specificity and safety, is increasingly utilized in both preclinical and clinical research for CNS ailments. As our comprehension of the pathophysiology of these conditions deepens, gene therapy stands out as a versatile and promising strategy with the potential to both prevent and treat these diseases. Despite the remarkable progress in refining and enhancing the structural design of gene therapy agents, substantial obstacles persist in their effective and safe delivery within living systems. To surmount these obstacles, a diverse array of gene delivery systems has been devised and continuously improved. Notably, Adeno-Associated Virus (AAVs)-based viral gene vectors and lipid-based nanocarriers have each advanced the in vivo delivery of gene therapies to various extents. This review aims to concisely summarize the pathophysiological foundations of CNS diseases and to shed light on the latest advancements in gene delivery vector technologies. It discusses the primary categories of these vectors, their respective advantages and limitations, and their specialized uses in the context of gene therapy delivery.

Transcytosis: an effective mechanism to enhance nanoparticle extravasation and infiltration through biological barriers

Nanoparticles (NPs)1have been explored as drugs carriers for treating tumors and central nervous system (CNS)2diseases and for oral administration. However, they lack satisfactory clinical efficacy due to poor extravasation and infiltration through biological barriers to target tissues. Most clinical antitumor NPs have been designed based on enhanced permeability and retention effects which are insufficient and heterogeneous in human tumors. The tight junctions33TJs: tight junctionsof the blood-brain barrier44BBB: blood-brain barrierand the small intestinal epithelium severely impede NPs from being transported into the CNS and blood circulation, respectively. By contrast, transcytosis enables NPs to bypass these physiological barriers and enhances their infiltration into target tissues by active transport. Here, we systematically review the mechanisms and putative application of NP transcytosis for targeting tumor and CNS tissues, explore oral NP administration, and propose future research directions in the field of NP transcytosis.

Efficacy and safety of focused ultrasound-mediated blood-brain barrier opening in Alzheimer's disease: A systematic review and meta-analysis

Background

Alzheimer's disease (AD) manifests as an insidiously progressive neurodegenerative pathology, wherein the current therapeutic armamentarium remains constrained to symptomatic management, highlighting an urgent need for innovative therapies.

Objective

This meta-analysis systematically conducts an assessment of the safety and efficacy of focused ultrasound (FUS)-mediated reversible blood-brain barrier opening (BBBO) in AD, while further exploring its potential associations with cognitive function and amyloid-β (Aβ) deposition in patients.

Methods

PubMed, Embase, CNKI, Cochrane Library, and Web of Science were searched in this study. The study protocol has been registered with PROSPERO (registration number, CRD42024585286). ROBINS-I tool was used to assess the risk of bias, followed by further data analysis.

Results

Fifty-seven AD patients from eight distinct clinical studies were systematically incorporated into the meta-analytical framework. The time span was from 2018 to 2023. After FUS-mediated BBBO, the analysis demonstrated significant outcomes of FUS for both safety (OR: 0.88; 95% CI: 0.75-0.98, p < 0.01) and efficacy (OR: 0.91; 95% CI: 0.61-1.00, p < 0.01). There was no deterioration of cognitive function after surgery, and the observed adverse events were minor and temporary in nature.

Conclusions

This meta-analysis underscores the potential of FUS as a non-invasive, safe, and effective method for enhancing BBB permeability in AD patients, offering a promising avenue for targeted drug delivery and disease modification. Future multicenter studies with larger sample sizes and standardized methodologies are warranted to confirm these results and explore the integration of FUS with existing and emerging AD therapies.

Engineering Stimuli-Responsive Materials for Precision Medicine

Over the past decade, precision medicine has garnered increasing attention, making significant strides in discovering new therapeutic drugs and mechanisms, resulting in notable achievements in symptom alleviation, pain reduction, and extended survival rates. However, the limited target specificity of primary drugs and inter-individual differences have often necessitated high-dosage strategies, leading to challenges such as restricted deep tissue penetration rates and systemic side effects. Material science advancements present a promising avenue for these issues. By leveraging the distinct internal features of diseased regions and the application of specific external stimuli, responsive materials can be tailored to achieve targeted delivery, controllable release, and specific biochemical reactions. This review aims to highlight the latest advancements in stimuli-responsive materials and their potential in precision medicine. Initially, we introduce disease-related internal stimuli and capable external stimuli, elucidating the reaction principles of responsive functional groups. Subsequently, we provide a detailed analysis of representative pre-clinical achievements of stimuli responsive materials across various clinical applications, including enhancements in the treatment of cancers, injury diseases, inflammatory diseases, infection diseases, and high-throughput microfluidic biosensors. Finally, we discuss some clinical challenges, such as off-target effects, long-term impacts of nano-materials, potential ethical concerns, and offer insights into future perspectives of stimuli-responsive materials.

The protective effects of gastrodin on neurological disorders: an update and future perspectives

Neurological disorders are characterized by high mortality and disability rates. Furthermore, the burden associated with disability and mortality resulting from neurological disorders has been increasing at an alarming rate. Botanical drugs and their bioactive components have emerged as a prominent area of research, offering a promising avenue for developing novel alternatives for treating neurological diseases. Gastrodin is the principal active component derived from the traditional Chinese medicinal plant Gastrodia elata Blume (GEB). Existing literature reveals that gastrodin exerts various pharmacological protective actions against neurological disorders. This review aimed to collate novel literature on gastrodin for treating neurological disorders from Web of Science, PubMed, Embase and CNKI. The pharmacokinetics of gastrodin, its therapeutic role in neurological disorders, the main mechanisms of action and clinical application were addressed. Furthermore, a detailed overview of gastrodin drug delivery systems and physical enhancement methods was presented, offering invaluable insights into potential research and the extensive applications of gastrodin.

Cerebral biomimetic nano-drug delivery systems: A frontier strategy for immunotherapy

Brain diseases are a significant threat to human health, especially in the elderly, and this problem is growing as the aging population increases. Efficient brain-targeted drug delivery has been the greatest challenge in treating brain disorders due to the unique immune environment of the brain, including the blood-brain barrier (BBB). Recently, cerebral biomimetic nano-drug delivery systems (CBNDSs) have provided a promising strategy for brain targeting by mimicking natural biological materials. Herein, this review explores the latest understanding of the immune microenvironment of the brain, emphasizing the immune mechanisms of the occurrence and progression of brain disease. Several brain targeting systems are summarized, including cell-based, exosome-based, protein-based, and microbe-based CBNDSs, and their immunological mechanisms are highlighted. Moreover, given the rise of immunotherapy, the latest applications of CBNDSs in immunotherapy are also discussed. This review provides a comprehensive understanding of CBNDSs and serves as a guideline for immunotherapy in treating brain diseases. In addition, it provides inspiration for the future of CBNDSs.

Microenvironment Self-Adaptive Nanomedicine Promotes Spinal Cord Repair by Suppressing Inflammation Cascade and Neural Apoptosis

Despite various biomaterial-based strategies are tried in spinal cord injury (SCI), developing safe and effective microinvasive pharmacotherapy strategies is still an unmet clinical need. Stimuli-responsive nanomedicine has emerged as a promising non-invasion technology, which enhances drug delivery and promotes functional recovery following SCI. Considering the multiple progressive pathological events and the blood spinal cord barrier (BSCB) associating SCI, a microenvironment self-adaptive nanoparticle (custom-designed with rabies virus glycoprotein 29-RVG29 and hyaluronic acid-HA, RHNP) capable of consistently crossing the BSCB and selectively targeting inflammatory cells and neural cells based on different stages of SCI are developed. The data indicated that RHNP can effectively traverse the BSCB through RVG29, and adaptively modulate cellular internalization by selectively exposing either HA or RVG29 through diselenide bonds, depending on pathological reactive oxygen species (ROS) signals. Furthermore, curcumin is loaded into RHNP (RHNP-Cur) to improve motor function and coordination of hind-limbs in a traumatic SCI mouse model. This study finds that RHNP-Cur exhibited inhibitory effects on the inflammatory cascade originating from M1 microglia/macrophages and neurotoxic astrocytes, and protected neural cells from inflammation-induced apoptosis during nerve regeneration. Collectively, the work provides a microenvironment self-adaptive nanomedicine which enables efficient microinvasive treatment of SCI.

Medical Ultrasound Application Beyond Diagnosis: Insights From Ultrasound Sensing and Biological Response

Ultrasound (US) can easily penetrate media with excellent spatial precision corresponding to its wavelength. Naturally, US plays a pivotal role in the echolocation abilities of certain mammals such as bats and dolphins. In addition, medical US generated by transducers interact with tissues via delivering ultrasonic energy in the modes of heat generation, exertion of acoustic radiation force (ARF), and acoustic cavitation. Based on the principle of echolocation, various assistive devices for visual impairment people have been developed. High-Intensity Focused Ultrasound (HIFU) are developed for targeted ablation and tissue destruction. Besides thermal ablation, histotripsy with US is designed to damage tissue purely via mechanical effect without thermal coagulation. Low-Intensity Focused Ultrasound (LIFU) has been proven to be an effective stimulation method for neuromodulation. Furthermore, US has been reported to transiently increase the permeability of biological membranes, enabling acoustic transfection and blood-brain barrier open. All of these advances in US are changing the clinic. This review mainly introduces the advances in these aspects, focusing on the physical and biological principles, challenges, and future direction.

The effect of combined ultrasound stimulation and gastrodin on seizures in mice

Both physiotherapy and medicine play essential roles in the treatment of epilepsy. The purpose of this research was to evaluate the efficacy of the combined therapy with focus ultrasound stimulation (FUS) and gastrodin (GTD) on seizures in a mouse model. Kainic acid-induced seizure mice were divided into five groups randomly: sham, FUS, saline + sham, GTD + sham and GTD + FUS. The results showed that combined therapy with ultrasound stimulation and gastrodin can significantly reduce the number and duration of seizures in GTD + FUS group. 9.4T magnetic resonance imaging and histologic staining results revealed the underlying mechanism of the combined therapy may be that ultrasound stimulation increases cell membrane permeability to increase GTD concentration in brain. In addition, we verified the safety of FUS combined with GTD therapy. This research provides a new strategy for neurological disorders combining treatment of physical neuromodulation and medicine.

An ultrasound-activated piezoelectric sonosensitizer enhances mitochondrial depolarization for effective treatment of orthotopic glioma

Despite the significant advancements in piezoelectric materials for sonodynamic therapy (SDT), the suppression of orthotopic glioma remains challenging, primarily due to the unclear mechanism and the restriction of blood-brain barrier (BBB). Herein, we proposed that layered piezoelectric SrBi2Ta2O9 nanoparticles (SBTO NPs) could effectively depolarize the mitochondrial membrane potential (ΔΨm) of glioma cells under ultrasound (US) exposure. The US-induced band bending in SBTO NPs enhanced redox ability, promoting an increase in reactive oxygen species (ROS) generation. The in vitro results proved that SBTO NPs selectively accumulated in mitochondria under US and induced apoptosis in a mitochondrial depolarization manner mediated by the generation of ROS and free charges. Furthermore, SBTO NPs could cross the BBB and then accumulate in gliomas through US/microbubbles (MBs) procedure and protein-mediated transport. The therapeutic effect of piezoelectric SBTO NPs mediated SDT was proved in the orthotopic glioma mouse model. As validated by the histopathological observation and the long-term evaluation, the good biocompatibility and biosafety of SBTO NPs make it possible for deep tumor therapy, and worthy for further preclinical study. STATEMENT OF SIGNIFICANCE: Employing piezoelectric sonosensitizers for sonodynamic therapy (SDT) has emerged as a promising strategy for cancer treatment; however, the unclear mechanism and blood-brain barrier (BBB) limit the effectiveness of SDT in glioma. Herein, we developed piezoelectric SrBi2Ta2O9 nanoparticles (SBTO NPs) with a built-in electric field for glioma treatment and explored the underlying therapeutic mechanism. Notably, SBTO NPs selectively accumulated in mitochondria under ultrasound (US) and induced apoptosis in a mitochondrial depolarization manner, which is mediated by the generation of reactive oxygen species (ROS) and free charges. In an orthotopic glioma mouse model, SBTO NPs were delivered into the glioma through US/microbubbles and transferrin-mediated transport pathways, inhibiting tumor growth. This work provides a new paradigm for the treatment of orthotopic glioma and other tumor types.

Amyloid-β-targeting immunotherapies for Alzheimer's disease

Recent advances in clinical passive immunotherapy have provided compelling evidence that eliminating amyloid-β (Aβ) slows cognitive decline in Alzheimer's disease (AD). However, the modest benefits and side effects observed in clinical trials indicate that current immunotherapy therapy is not a panacea, highlighting the need for a deeper understanding of AD mechanisms and the significance of early intervention through optimized immunotherapy or immunoprevention. This review focuses on the centrality of Aβ pathology in AD and summarizes recent clinical progress in passive and active immunotherapies targeting Aβ, discussing their lessons and failures to inform future anti-Aβ biotherapeutics design. Various delivery strategies to optimize Aβ-targeting immunotherapies are outlined, highlighting their benefits and drawbacks in overcoming challenges such as poor stability and limited tissue accessibility of anti-Aβ biotherapeutics. Additionally, the perspectives and challenges of immunotherapy and immunoprevention targeting Aβ are concluded in the end, aiming to guide the development of next-generation anti-Aβ immunotherapeutic agents towards improved efficacy and safety.

Open-Source Throttling of CD8+ T Cells in Brain with Low-Intensity Focused Ultrasound-Guided Sequential Delivery of CXCL10, IL-2, and aPD-L1 for Glioblastoma Immunotherapy

Improving clinical immunotherapy for glioblastoma (GBM) relies on addressing the immunosuppressive tumor microenvironment (TME). Enhancing CD8+ T cell infiltration and preventing its exhaustion holds promise for effective GBM immunotherapy. Here, a low-intensity focused ultrasound (LIFU)-guided sequential delivery strategy is developed to enhance CD8+ T cells infiltration and activity in the GBM region. The sequential delivery of CXC chemokine ligand 10 (CXCL10) to recruit CD8+ T cells and interleukin-2 (IL-2) to reduce their exhaustion is termed an "open-source throttling" strategy. Consequently, up to 3.39-fold of CD8+ T cells are observed with LIFU-guided sequential delivery of CXCL10, IL-2, and anti-programmed cell death 1 ligand 1 (aPD-L1), compared to the free aPD-L1 group. The immune checkpoint inhibitors (ICIs) therapeutic efficacy is substantially enhanced by the reversed immunosuppressive TME due to the expansion of CD8+ T cells, resulting in the elimination of tumor, prolonged survival time, and long-term immune memory establishment in orthotopic GBM mice. Overall, LIFU-guided sequential cytokine and ICIs delivery offers an "open-source throttling" strategy of CD8+ T cells, which may present a promising strategy for brain-tumor immunotherapy.

Designed Nanodrugs for Ultrasonic Removal of Toxic Polyglutamine Aggregates from Neuron Cells

Clearing of toxic polyglutamine aggregates from neuronal cells is crucial for ameliorating Huntington's disease. However, such clearance is challenging, requiring the targeting of affected neuron cells in the brain, followed by the removal of polyglutamine from cells. Here we report a designed nanodrug that can be used for the ultrasound-based removal of toxic polyglutamine aggregates from neuron cells. The nanodrug is composed of a sonosensitizer molecule, chlorin e6- or protoporphyrin IX-loaded polymer micelle of 20-30 nm in size that rapidly delivers the sonosensitizer into the cell nucleus. Ultrasound exposure of these cells generates singlet oxygen in the nucleus/perinuclear region that induces strong autophagic flux and clears toxic polyglutamine aggregates from cells. It has been demonstrated that the nanodrug and ultrasound treatment can enhance the cell survival against polyglutamine aggregates by 4 times. This result suggests that the nanodrug can be designed for focused ultrasound-based wireless treatment of various neurodegenerative diseases.

A review of temporal interference, nanoparticles, ultrasound, gene therapy, and designer receptors for Parkinson disease

In this review, we summarize preclinical and clinical trials investigating innovative neuromodulatory approaches for Parkinson disease (PD) motor symptom management. We highlight the following technologies: temporal interference, nanoparticles for drug delivery, blood-brain barrier opening, gene therapy, optogenetics, upconversion nanoparticles, magnetothermal nanoparticles, magnetoelectric nanoparticles, ultrasound-responsive nanoparticles, and designer receptors exclusively activated by designer drugs. These studies establish the basis for novel and promising neuromodulatory treatments for PD motor symptoms.

Neurological glycogen storage diseases and emerging therapeutics

Glycogen storage diseases (GSDs) comprise a group of inherited metabolic disorders characterized by defects in glycogen metabolism, leading to abnormal glycogen accumulation in multiple tissues, most notably affecting the liver, skeletal muscle, and heart. Recent findings have uncovered the importance of glycogen metabolism in the brain, sustaining a myriad of physiological functions and linking its perturbation to central nervous system (CNS) pathology. This link resulted in classification of neurological-GSDs (n-GSDs), a group of diseases with shared deficits in neurological glycogen metabolism. The n-GSD patients exhibit a spectrum of clinical presentations with common etiology while requiring tailored therapeutic approaches from the traditional GSDs. Recent research has elucidated the genetic and biochemical mechanisms and pathophysiological basis underlying different n-GSDs. Further, the last decade has witnessed some promising developments in novel therapeutic approaches, including enzyme replacement therapy (ERT), substrate reduction therapy (SRT), small molecule drugs, and gene therapy targeting key aspects of glycogen metabolism in specific n-GSDs. This preclinical progress has generated noticeable success in potentially modifying disease course and improving clinical outcomes in patients. Herein, we provide an overview of current perspectives on n-GSDs, emphasizing recent advances in understanding their molecular basis, therapeutic developments, underscore key challenges and the need to deepen our understanding of n-GSDs pathogenesis to develop better therapeutic strategies that could offer improved treatment and sustainable benefits to the patients.

Radiation enhancement using focussed ultrasound-stimulated microbubbles for head and neck cancer: A phase 1 clinical trial

BACKGROUND AND PURPOSE

Preclinical research demonstrated that the exposure of microbubbles (intravascular gas microspheres) to focussed ultrasound within the targeted tumour upregulates pro-apoptotic pathways and enhances radiation-induced tumour cell death. This study aimed to assess the safety and efficacy of magnetic resonance (MR)-guided focussed ultrasound-stimulated microbubbles (MRgFUS-MB) for head and neck cancers (HN).

MATERIALS AND METHODS

This prospective phase 1 clinical trial included patients with newly diagnosed or recurrent HN cancer (except nasopharynx malignancies) for whom locoregional radiotherapy with radical- or palliative-intent as deemed appropriate. Patients with contraindications for microbubble administration or contrast-enhanced MR were excluded. MR-coupled focussed ultrasound sonicated intravenously administered microbubbles within the MR-guided target volume. Patients receiving 5-10 and 33-35 radiation fractions were planned for 2 and 3 MRgFUS-MB treatments, respectively. Primary endpoint was toxicity per CTCAEv5.0. Secondary endpoint was tumour response at 3 months per RECIST 1.1 criteria.

RESULTS

Twelve patients were enrolled between Jun/2020 and Nov/2023, but 1 withdrew consent. Eleven patients were included in safety analysis. Median follow-up was 7 months (range, 0.3-38). Most patients had oropharyngeal cancer (55 %) and received 20-30 Gy/5-10 fractions (63 %). No systemic toxicity or MRgFUS-MB-related adverse events occurred. The most severe acute adverse events were radiation-related grade 3 toxicities in 6 patients (55 %; dermatitis in 3, mucositis in 1, dysphagia in 6). No radiation necrosis or grade 4/5 toxicities were reported. 8 patients were included in the 3-month tumour response assessment: 4 had partial response (50 %), 3 had complete response (37.5 %), and 1 had progressive disease (12.5 %).

CONCLUSIONS

MRgFUS-MB treatment was safe and associated with high rates of tumour response at 3 months.

Advancements in strategies for overcoming the blood-brain barrier to deliver brain-targeted drugs

The blood-brain barrier is known to consist of a variety of cells and complex inter-cellular junctions that protect the vulnerable brain from neurotoxic compounds; however, it also complicates the pharmacological treatment of central nervous system disorders as most drugs are unable to penetrate the blood-brain barrier on the basis of their own structural properties. This dramatically diminished the therapeutic effect of the drug and compromised its biosafety. In response, a number of drugs are often delivered to brain lesions in invasive ways that bypass the obstruction of the blood-brain barrier, such as subdural administration, intrathecal administration, and convection-enhanced delivery. Nevertheless, these intrusive strategies introduce the risk of brain injury, limiting their clinical application. In recent years, the intensive development of nanomaterials science and the interdisciplinary convergence of medical engineering have brought light to the penetration of the blood-brain barrier for brain-targeted drugs. In this paper, we extensively discuss the limitations of the blood-brain barrier on drug delivery and non-invasive brain-targeted strategies such as nanomedicine and blood-brain barrier disruption. In the meantime, we analyze their strengths and limitations and provide outlooks on the further development of brain-targeted drug delivery systems.

Nanocarrier drug delivery system: promising platform for targeted depression therapy

Depression is a chronic mental disorder characterized by persistent low mood and loss of interest. Treatments for depression are varied but may not be sufficient cure. Drug-based treatment regimens have drawbacks such as slow onset of action, low bioavailability, and drug side effects. Nanocarrier Drug Delivery Systems (NDDS) has received increasing attention for brain drug delivery since it assists the drug through the blood-brain barrier and improves bioavailability, which may be beneficial for treating depression. Due to the particle size and physicochemical properties of nanocarriers, it presents a promise to improve the stability and solubility of antidepressants, thereby enhancing the drug concentration. Moreover, ligand-modified nanocarriers can be taken as a target direct medicines release system and reduce drug side effects. The purpose of the present review is to provide an up-to-date understanding of the Nanocarrier drug delivery system and relevant antidepressants in different routes of ingestion, to lay a foundation for the treatment of patients with depression.

Ultrasound-Based Micro-/Nanosystems for Biomedical Applications

Due to the intrinsic non-invasive nature, cost-effectiveness, high safety, and real-time capabilities, besides diagnostic imaging, ultrasound as a typical mechanical wave has been extensively developed as a physical tool for versatile biomedical applications. Especially, the prosperity of nanotechnology and nanomedicine invigorates the landscape of ultrasound-based medicine. The unprecedented surge in research enthusiasm and dedicated efforts have led to a mass of multifunctional micro-/nanosystems being applied in ultrasound biomedicine, facilitating precise diagnosis, effective treatment, and personalized theranostics. The effective deployment of versatile ultrasound-based micro-/nanosystems in biomedical applications is rooted in a profound understanding of the relationship among composition, structure, property, bioactivity, application, and performance. In this comprehensive review, we elaborate on the general principles regarding the design, synthesis, functionalization, and optimization of ultrasound-based micro-/nanosystems for abundant biomedical applications. In particular, recent advancements in ultrasound-based micro-/nanosystems for diagnostic imaging are meticulously summarized. Furthermore, we systematically elucidate state-of-the-art studies concerning recent progress in ultrasound-based micro-/nanosystems for therapeutic applications targeting various pathological abnormalities including cancer, bacterial infection, brain diseases, cardiovascular diseases, and metabolic diseases. Finally, we conclude and provide an outlook on this research field with an in-depth discussion of the challenges faced and future developments for further extensive clinical translation and application.

An Overview on the Physiopathology of the Blood-Brain Barrier and the Lipid-Based Nanocarriers for Central Nervous System Delivery

The state of well-being and health of our body is regulated by the fine osmotic and biochemical balance established between the cells of the different tissues, organs, and systems. Specific districts of the human body are defined, kept in the correct state of functioning, and, therefore, protected from exogenous or endogenous insults of both mechanical, physical, and biological nature by the presence of different barrier systems. In addition to the placental barrier, which even acts as a linker between two different organisms, the mother and the fetus, all human body barriers, including the blood-brain barrier (BBB), blood-retinal barrier, blood-nerve barrier, blood-lymph barrier, and blood-cerebrospinal fluid barrier, operate to maintain the physiological homeostasis within tissues and organs. From a pharmaceutical point of view, the most challenging is undoubtedly the BBB, since its presence notably complicates the treatment of brain disorders. BBB action can impair the delivery of chemical drugs and biopharmaceuticals into the brain, reducing their therapeutic efficacy and/or increasing their unwanted bioaccumulation in the surrounding healthy tissues. Recent nanotechnological innovation provides advanced biomaterials and ad hoc customized engineering and functionalization methods able to assist in brain-targeted drug delivery. In this context, lipid nanocarriers, including both synthetic (liposomes, solid lipid nanoparticles, nanoemulsions, nanostructured lipid carriers, niosomes, proniosomes, and cubosomes) and cell-derived ones (extracellular vesicles and cell membrane-derived nanocarriers), are considered one of the most successful brain delivery systems due to their reasonable biocompatibility and ability to cross the BBB. This review aims to provide a complete and up-to-date point of view on the efficacy of the most varied lipid carriers, whether FDA-approved, involved in clinical trials, or used in in vitro or in vivo studies, for the treatment of inflammatory, cancerous, or infectious brain diseases.

Recent advances in stimuli-responsive controlled release systems for neuromodulation

Neuromodulation aims to modulate the signaling activity of neurons or neural networks by the precise delivery of electrical stimuli or chemical agents and is crucial for understanding brain function and treating brain disorders. Conventional approaches, such as direct physical stimulation through electrical or acoustic methods, confront challenges stemming from their invasive nature, dependency on wired power sources, and unstable therapeutic outcomes. The emergence of stimulus-responsive delivery systems harbors the potential to revolutionize neuromodulation strategies through the precise and controlled release of neurochemicals in a specific brain region. This review comprehensively examines the biological barriers controlled release systems may encounter in vivo and the recent advances and applications of these systems in neuromodulation. We elucidate the intricate interplay between the molecular structure of delivery systems and response mechanisms to furnish insights for material selection and design. Additionally, the review contemplates the prospects and challenges associated with these systems in neuromodulation. The overarching objective is to propel the application of neuromodulation technology in analyzing brain functions, treating brain disorders, and providing insightful perspectives for exploiting new systems for biomedical applications.

A dual-targeting therapeutic nanobubble for imaging-guided atherosclerosis treatment

Atherosclerosis is a cardiovascular disease that seriously endangers human health. Low shear stress (LSS) is recognized as a vital factor in causing chronic inflammatory and further inducing the occurrence and development of atherosclerosis. Targeting imaging and treatment are of substantial significance for the diagnosis and therapy of atherosclerosis. On this ground, a kind of ultrasound (US) imaging-guided therapeutic polymer nanobubbles (NBs) with dual targeting of magnetism and antibody was rationally designed and constructed for the efficiently treating LSS-mediated atherosclerosis. Under the combined targeting effect of an external magnetic field and antibodies, the drug-loaded therapeutic NBs can be effectively accumulated in the inflammatory area caused by LSS. Upon US irradiation, the NBs can be selectively disrupted, leading to the rapid release of the loaded drugs at the targeted site. Notably, the US irradiation generates a cavitation effect that induces repairable micro gaps in nearby cells, thereby enhancing the uptake of released drugs and further improving the therapeutic effect. The prominent US imaging, efficient anti-inflammatory effect and treatment outcome of LSS-mediated atherosclerosis had been verified in vivo on a surgically constructed LSS-atherosclerosis animal model. This work showcased the potential of the designed NBs with multifunctionality for in vivo imaging, dual-targeting, and drug delivery in the treatment of atherosclerosis.

Recent advances of focused ultrasound induced blood-brain barrier opening for clinical applications of neurodegenerative diseases

With the aging population on the rise, neurodegenerative disorders have taken center stage as a significant health concern. The blood-brain barrier (BBB) plays an important role to maintain the stability of central nervous system, yet it poses a formidable obstacle to delivering drugs for neurodegenerative disease therapy. Various methods have been devised to confront this challenge, each carrying its own set of limitations. One particularly promising noninvasive approach involves the utilization of focused ultrasound (FUS) combined with contrast agents-microbubbles (MBs) to achieve transient and reversible BBB opening. This review provides a comprehensive exploration of the fundamental mechanisms behind FUS/MBs-mediated BBB opening and spotlights recent breakthroughs in its application for neurodegenerative diseases. Furthermore, it addresses the current challenges and presents future perspectives in this field.

Exploring the Impact of Irradiation on Glioblastoma Blood-Brain-Barrier Permeability: Insights from Dynamic-Contrast-Enhanced-MRI and Histological Analysis

(1) Background: Glioblastoma (GB) presents a formidable challenge in neuro-oncology due to its aggressive nature, limited treatment options, and poor prognosis. The blood-brain barrier (BBB) complicates treatment by hindering drug delivery to the tumor site, particularly to the infiltrative cells in the margin of the tumor, which are mainly responsible for tumor recurrence. Innovative strategies are therefore needed to enhance drug delivery in the margins of the tumor. This study explores whether irradiation can enhance BBB permeability by assessing hemodynamic changes and the distribution of contrast agents in the core and the margins of GB tumors. (2) Methods: Mice grafted with U-87MG cells were exposed to increasing irradiation doses. The distribution of contrast agents and hemodynamic parameters was evaluated using both non-invasive magnetic resonance imaging (MRI) techniques with gadolinium-DOTA as a contrast agent and invasive histological analysis with Evans blue, a fluorescent vascular leakage marker. Diffusion-MRI was also used to assess cytotoxic effects. (3) Results: The histological study revealed a complex dose-dependent effect of irradiation on BBB integrity, with increased vascular leakage at 5 Gy but reduced leakage at higher doses (10 and 15 Gy). However, there was no significant increase in the diffusion of Gd-DOTA outside the tumor area by MRI. (4) Conclusions: The increase in BBB permeability could be an interesting approach to enhance drug delivery in glioblastoma margins for low irradiation doses. In this model, DCE-MRI analysis was of limited value in assessing the BBB opening in glioblastoma after irradiation.

Insights into Targeted and Stimulus-Responsive Nanocarriers for Brain Cancer Treatment

Brain cancers, especially glioblastoma multiforme, are associated with poor prognosis due to the limited efficacy of current therapies. Nanomedicine has emerged as a versatile technology to treat various diseases, including cancers, and has played an indispensable role in combatting the COVID-19 pandemic as evidenced by the role that lipid nanocarrier-based vaccines have played. The tunability of nanocarrier physicochemical properties -including size, shape, surface chemistry, and drug release kinetics- has resulted in the development of a wide range of nanocarriers for brain cancer treatment. These nanocarriers can improve the pharmacokinetics of drugs, increase blood-brain barrier transfer efficiency, and specifically target brain cancer cells. These unique features would potentially allow for more efficient treatment of brain cancer with fewer side effects and better therapeutic outcomes. This review provides an overview of brain cancers, current therapeutic options, and challenges to efficient brain cancer treatment. The latest advances in nanomedicine strategies are investigated with an emphasis on targeted and stimulus-responsive nanocarriers and their potential for clinical translation.

Translating ultrasound-mediated drug delivery technologies for CNS applications

Ultrasound enhances drug delivery into the central nervous system (CNS) by opening barriers between the blood and CNS and by triggering release of drugs from carriers. A key challenge in translating setups from in vitro to in vivo settings is achieving equivalent acoustic energy delivery. Multiple devices have now been demonstrated to focus ultrasound to the brain, with concepts emerging to also target the spinal cord. Clinical trials to date have used ultrasound to facilitate the opening of the blood-brain barrier. While most have focused on feasibility and safety considerations, therapeutic benefits are beginning to emerge. To advance translation of these technologies for CNS applications, researchers should standardise exposure protocol and fine-tune ultrasound parameters. Computational modelling should be increasingly used as a core component to develop both in vitro and in vivo setups for delivering accurate and reproducible ultrasound to the CNS. This field holds promise for transformative advancements in the management and pharmacological treatment of complex and challenging CNS disorders.

Radiation enhancement using focussed ultrasound-stimulated microbubbles for breast cancer: A Phase 1 clinical trial

BACKGROUND

Preclinical studies have demonstrated that tumour cell death can be enhanced 10- to 40-fold when radiotherapy is combined with focussed ultrasound-stimulated microbubble (FUS-MB) treatment. The acoustic exposure of microbubbles (intravascular gas microspheres) within the target volume causes bubble cavitation, which induces perturbation of tumour vasculature and activates endothelial cell apoptotic pathways responsible for the ablative effect of stereotactic body radiotherapy. Subsequent irradiation of a microbubble-sensitised tumour causes rapid increased tumour death. The study here presents the mature safety and efficacy outcomes of magnetic resonance (MR)-guided FUS-MB (MRgFUS-MB) treatment, a radioenhancement therapy for breast cancer.

METHODS AND FINDINGS

This prospective, single-center, single-arm Phase 1 clinical trial included patients with stages I-IV breast cancer with in situ tumours for whom breast or chest wall radiotherapy was deemed adequate by a multidisciplinary team (clinicaltrials.gov identifier: NCT04431674). Patients were excluded if they had contraindications for contrast-enhanced MR or microbubble administration. Patients underwent 2 to 3 MRgFUS-MB treatments throughout radiotherapy. An MR-coupled focussed ultrasound device operating at 800 kHz and 570 kPa peak negative pressure was used to sonicate intravenously administrated microbubbles within the MR-guided target volume. The primary outcome was acute toxicity per Common Terminology Criteria for Adverse Events (CTCAE) v5.0. Secondary outcomes were tumour response at 3 months and local control (LC). A total of 21 female patients presenting with 23 primary breast tumours were enrolled and allocated to intervention between August/2020 and November/2022. Three patients subsequently withdrew consent and, therefore, 18 patients with 20 tumours were included in the safety and LC analyses. Two patients died due to progressive metastatic disease before 3 months following treatment completion and were excluded from the tumour response analysis. The prescribed radiation doses were 20 Gy/5 fractions (40%, n = 8/20), 30 to 35 Gy/5 fractions (35%, n = 7/20), 30 to 40 Gy/10 fractions (15%, n = 3/20), and 66 Gy/33 fractions (10%, n = 2/20). The median follow-up was 9 months (range, 0.3 to 29). Radiation dermatitis was the most common acute toxicity (Grade 1 in 16/20, Grade 2 in 1/20, and Grade 3 in 2/20). One patient developed grade 1 allergic reaction possibly related to microbubbles administration. At 3 months, 18 tumours were evaluated for response: 9 exhibited complete response (50%, n = 9/18), 6 partial response (33%, n = 6/18), 2 stable disease (11%, n = 2/18), and 1 progressive disease (6%, n = 1/18). Further follow-up of responses indicated that the 6-, 12-, and 24-month LC rates were 94% (95% confidence interval [CI] [84%, 100%]), 88% (95% CI [75%, 100%]), and 76% (95% CI [54%, 100%]), respectively. The study's limitations include variable tumour sizes and dose fractionation regimens and the anticipated small sample size typical for a Phase 1 clinical trial.

CONCLUSIONS

MRgFUS-MB is an innovative radioenhancement therapy associated with a safe profile, potentially promising responses, and durable LC. These results warrant validation in Phase 2 clinical trials.

TRIAL REGISTRATION

clinicaltrials.gov, identifier NCT04431674.

Optimal timing for drug delivery into the hippocampus by focused ultrasound: A comparison of hydrophilic and lipophilic compounds

Aims

Previous studies have reported that focused ultrasound (FUS) helps modulate the blood-brain barrier (BBB). These studies have generally used the paracellular pathway owing to tight junction proteins (TJPs) regulation. However, BBB transport pathways also include diffusion and transcytosis. Few studies have examined transcellular transport across endothelial cells. We supposed that increased BBB permeability caused by FUS may affect transcytosis. We investigated drug delivery through transcytosis and paracellular transport to the brain after BBB modulation using FUS.

Main methods

FUS and microbubbles were applied to the hippocampus of rats, and were euthanized at 1, 4, 24, and 48 h after sonication. To investigate paracellular transport, we analyzed TJPs, including zona occludens-1 (ZO-1) and occludin. We also investigated caveola-mediated transcytosis by analyzing caveola formation and major facilitator superfamily domain-containing 2a (Mfsd2a) levels, which inhibit caveola vesicle formation.

Key findings

One hour after FUS, ZO-1 and occludin expression was the lowest and gradually increased over time, returning to baseline 24 h after FUS treatment. Compared with that of TJPs, caveola formation started to increase 1 h after FUS treatment and peaked at 4 h after FUS treatment before returning to baseline by 48 h after FUS treatment. Decreased Mfsd2a levels were observed at 1 h and 4 h after FUS treatment, indicating increased caveola formation.

Significance

FUS induces BBB permeability changes and regulates both paracellular transport and caveola-mediated transcytosis. However, a time difference was observed between these two mechanisms. Hence, when delivering drugs into the brain after FUS, the optimal drug administration timing should be determined by the mechanism by which each drug passes through the BBB.

Developing hydrogels for gene therapy and tissue engineering

Hydrogels are a class of highly absorbent and easily modified polymer materials suitable for use as slow-release carriers for drugs. Gene therapy is highly specific and can overcome the limitations of traditional tissue engineering techniques and has significant advantages in tissue repair. However, therapeutic genes are often affected by cellular barriers and enzyme sensitivity, and carrier loading of therapeutic genes is essential. Therapeutic gene hydrogels can well overcome these difficulties. Moreover, gene-therapeutic hydrogels have made considerable progress. This review summarizes the recent research on carrier gene hydrogels for the treatment of tissue damage through a summary of the most current research frontiers. We initially introduce the classification of hydrogels and their cross-linking methods, followed by a detailed overview of the types and modifications of therapeutic genes, a detailed discussion on the loading of therapeutic genes in hydrogels and their characterization features, a summary of the design of hydrogels for therapeutic gene release, and an overview of their applications in tissue engineering. Finally, we provide comments and look forward to the shortcomings and future directions of hydrogels for gene therapy. We hope that this article will provide researchers in related fields with more comprehensive and systematic strategies for tissue engineering repair and further promote the development of the field of hydrogels for gene therapy.

Nanotherapeutics for Alleviating Anesthesia-Associated Complications

Current management of anesthesia-associated complications falls short in terms of both efficacy and safety. Nanomaterials with versatile properties and unique nano-bio interactions hold substantial promise as therapeutics for addressing these complications. This review conducts a thorough examination of the existing nanotherapeutics and highlights the strategies for developing prospective nanomedicines to mitigate anesthetics-related toxicity. Initially, general, regional, and local anesthesia along with the commonly used anesthetics and related prevalent side effects are introduced. Furthermore, employing nanotechnology to prevent and alleviate the complications of anesthetics is systematically demonstrated from three aspects, that is, developing 1) safe nano-formulization for anesthetics; 2) nano-antidotes to sequester overdosed anesthetics and alter their pharmacokinetics; 3) nanomedicines with pharmacodynamic activities to treat anesthetics toxicity. Finally, the prospects and challenges facing the clinical translation of nanotherapeutics for anesthesia-related complications are discussed. This work provides a comprehensive roadmap for developing effective nanotherapeutics to prevent and mitigate anesthesia-associated toxicity, which can potentially revolutionize the management of anesthesia complications.

From concept to early clinical trials: 30 years of microbubble-based ultrasound-mediated drug delivery research

Ultrasound mediated drug delivery, a promising therapeutic modality, has evolved remarkably over the past three decades. Initially designed to enhance contrast in ultrasound imaging, microbubbles have emerged as a main vector for drug delivery, offering targeted therapy with minimized side effects. This review addresses the historical progression of this technology, emphasizing the pivotal role microbubbles play in augmenting drug extravasation and targeted delivery. We explore the complex mechanisms behind this technology, from stable and inertial cavitation to diverse acoustic phenomena, and their applications in medical fields. While the potential of ultrasound mediated drug delivery is undeniable, there are still challenges to overcome. Balancing therapeutic efficacy and safety and establishing standardized procedures are essential areas requiring attention. A multidisciplinary approach, gathering collaborations between researchers, engineers, and clinicians, is important for exploiting the full potential of this technology. In summary, this review highlights the potential of using ultrasound mediated drug delivery in improving patient care across various medical conditions.

Exploiting Sound for Emerging Applications of Extracellular Vesicles

Extracellular vesicles are nano- to microscale, membrane-bound particles released by cells into extracellular space, and act as carriers of biomarkers and therapeutics, holding promising potential in translational medicine. However, the challenges remain in handling and detecting extracellular vesicles for disease diagnosis as well as exploring their therapeutic capability for disease treatment. Here, we review the recent engineering and technology advances by leveraging the power of sound waves to address the challenges in diagnostic and therapeutic applications of extracellular vesicles and biomimetic nanovesicles. We first introduce the fundamental principles of sound waves for understanding different acoustic-assisted extracellular vesicle technologies. We discuss the acoustic-assisted diagnostic methods including the purification, manipulation, biosensing, and bioimaging of extracellular vesicles. Then, we summarize the recent advances in acoustically enhanced therapeutics using extracellular vesicles and biomimetic nanovesicles. Finally, we provide perspectives into current challenges and future clinical applications of the promising extracellular vesicles and biomimetic nanovesicles powered by sound.

Ultrasound technology assisted colloidal nanocrystal synthesis and biomedical applications

Non-invasive and high spatiotemporal resolution mythologies for the diagnosis and treatment of disease in clinical medicine promote the development of modern medicine. Ultrasound (US) technology provides a non-invasive, real-time, and cost-effective clinical imaging modality, which plays a significant role in chemical synthesis and clinical translation, especially in in vivo imaging and cancer therapy. On the one hand, the US treatment is usually accompanied by cavitation, leading to high temperature and pressure, so-called "hot spot", playing a significant role in sonochemical-based colloidal synthesis. Compared with the classical nucleation synthetic method, the sonochemical synthesis strategy presents high efficiency for the fabrication of colloidal nanocrystals due to its fast nucleation and growth procedure. On the other hand, the US is attractive for in vivo and medical treatment, with applications increasing with the development of novel contrast agents, such as the micro and nano bubbles, which are widely used in neuromodulation, with which the US can breach the blood-brain barrier temporarily and safely, opening a new door to neuromodulation and therapy. In terms of cancer treatment, sonodynamic therapy and US-assisted synergetic therapy show great effects against cancer and sonodynamic immunotherapy present unparalleled potentiality compared with other synergetic therapies. Further development of ultrasound technology can revolutionize both chemical synthesis and clinical translation by improving efficiency, precision, and accessibility while reducing environmental impact and enhancing patient care. In this paper, we review the US-assisted sonochemical synthesis and biological applications, to promote the next generation US technology-assisted applications.

Shedding light on ultrasound in action: Optical and optoacoustic monitoring of ultrasound brain interventions

Monitoring brain responses to ultrasonic interventions is becoming an important pillar of a growing number of applications employing acoustic waves to actuate and cure the brain. Optical interrogation of living tissues provides a unique means for retrieving functional and molecular information related to brain activity and disease-specific biomarkers. The hybrid optoacoustic imaging methods have further enabled deep-tissue imaging with optical contrast at high spatial and temporal resolution. The marriage between light and sound thus brings together the highly complementary advantages of both modalities toward high precision interrogation, stimulation, and therapy of the brain with strong impact in the fields of ultrasound neuromodulation, gene and drug delivery, or noninvasive treatments of neurological and neurodegenerative disorders. In this review, we elaborate on current advances in optical and optoacoustic monitoring of ultrasound interventions. We describe the main principles and mechanisms underlying each method before diving into the corresponding biomedical applications. We identify areas of improvement as well as promising approaches with clinical translation potential.

Ultrasound-nanovesicles interplay for theranostics

Nanovesicles (NVs) are widely used in the treatment and diagnosis of diseases due to their excellent vascular permeability, good biocompatibility, high loading capacity, and easy functionalization. However, their yield and in vivo penetration depth limitations and their complex preparation processes still constrain their application and development. Ultrasound, as a fundamental external stimulus with deep tissue penetration, concentrated energy sources, and good safety, has been proven to be a patient-friendly and highly efficient strategy to overcome the restrictions of traditional clinical medicine. Recent research has shown that ultrasound can drive the generation of NVs, increase their yield, simplify their preparation process, and provide direct therapeutic effects and intelligent control to enhance the therapeutic effect of NVs. In addition, NVs, as excellent drug carriers, can enhance the targeting efficiency of ultrasound-based sonodynamic therapy or sonogenetic regulation and improve the accuracy of ultrasound imaging. This review provides a detailed introduction to the classification, generation, and modification strategies of NVs, emphasizing the impact of ultrasound on the formation of NVs and summarizing the enhanced treatment and diagnostic effects of NVs combined with ultrasound for various diseases.

A multicellular brain spheroid model for studying the mechanisms and bioeffects of ultrasound-enhanced drug penetration beyond the blood‒brain barrier

The blood‒brain barrier (BBB) acts as a hindrance to drug therapy reaching the brain. With an increasing incidence of neurovascular diseases and brain cancer metastases, there is a need for an ideal in vitro model to develop novel methodologies for enhancing drug delivery to the brain. Here, we established a multicellular human brain spheroid model that mimics the BBB both architecturally and functionally. Within the spheroids, endothelial cells and pericytes localized to the periphery, while neurons, astrocytes, and microglia were distributed throughout. Ultrasound-targeted microbubble cavitation (UTMC) is a novel noninvasive technology for enhancing endothelial drug permeability. We utilized our three-dimensional (3D) model to study the feasibility and mechanisms regulating UTMC-induced hyperpermeability. UTMC caused a significant increase in the penetration of 10 kDa Texas red dextran (TRD) into the spheroids, 100 µm beyond the BBB, without compromising cell viability. This hyperpermeability was dependent on UTMC-induced calcium (Ca2+) influx and endothelial nitric oxide synthase (eNOS) activation. Our 3D brain spheroid model, with its intact and functional BBB, offers a valuable platform for studying the bioeffects of UTMC, including effects occurring spatially distant from the endothelial barrier.

Micro/nanosystems for controllable drug delivery to the brain

Drug delivery to the brain is crucial in the treatment for central nervous system disorders. While significant progress has been made in recent years, there are still major challenges in achieving controllable drug delivery to the brain. Unmet clinical needs arise from various factors, including controlled drug transport, handling large drug doses, methods for crossing biological barriers, the use of imaging guidance, and effective models for analyzing drug delivery. Recent advances in micro/nanosystems have shown promise in addressing some of these challenges. These include the utilization of microfluidic platforms to test and validate the drug delivery process in a controlled and biomimetic setting, the development of novel micro/nanocarriers for large drug loads across the blood-brain barrier, and the implementation of micro-intervention systems for delivering drugs through intraparenchymal or peripheral routes. In this article, we present a review of the latest developments in micro/nanosystems for controllable drug delivery to the brain. We also delve into the relevant diseases, biological barriers, and conventional methods. In addition, we discuss future prospects and the development of emerging robotic micro/nanosystems equipped with directed transportation, real-time image guidance, and closed-loop control.

Breaking Barriers in Neuro-Oncology: A Scoping Literature Review on Invasive and Non-Invasive Techniques for Blood-Brain Barrier Disruption

The blood-brain barrier (BBB) poses a significant challenge to drug delivery for brain tumors, with most chemotherapeutics having limited permeability into non-malignant brain tissue and only restricted access to primary and metastatic brain cancers. Consequently, due to the drug's inability to effectively penetrate the BBB, outcomes following brain chemotherapy continue to be suboptimal. Several methods to open the BBB and obtain higher drug concentrations in tumors have been proposed, with the selection of the optimal method depending on the size of the targeted tumor volume, the chosen therapeutic agent, and individual patient characteristics. Herein, we aim to comprehensively describe osmotic disruption with intra-arterial drug administration, intrathecal/intraventricular administration, laser interstitial thermal therapy, convection-enhanced delivery, and ultrasound methods, including high-intensity focused and low-intensity ultrasound as well as tumor-treating fields. We explain the scientific concept behind each method, preclinical/clinical research, advantages and disadvantages, indications, and potential avenues for improvement. Given that each method has its limitations, it is unlikely that the future of BBB disruption will rely on a single method but rather on a synergistic effect of a combined approach. Disruption of the BBB with osmotic infusion or high-intensity focused ultrasound, followed by the intra-arterial delivery of drugs, is a promising approach. Real-time monitoring of drug delivery will be necessary for optimal results.