Ultrasound and Microbubbles for Targeted Drug Delivery to the Lung Endothelium in ARDS: Cellular Mechanisms and Therapeutic Opportunities

Improving the Efficiency of Ultrasound and Microbubble Mediated Gene Delivery by Manipulation of Microbubble Lipid Composition

Ultrasound and microbubble-mediated gene delivery is emerging as a powerful nonviral gene delivery approach due to its ability to target various tissues. Since microbubble cavitation plays a crucial role in gene delivery, factors affecting cavitation, such as microbubble composition, size, ultrasound pressure, frequency, and pulse interval, can directly affect the efficiency of gene delivery. The effect of ultrasound parameters on gene delivery efficiency has been systematically investigated in numerous studies. However, relatively few studies have investigated the influence of different microbubble compositions on gene delivery. In this paper, we report that microbubbles made with the same lipids but different poly(ethylene glycol) (PEG) derivatives lead to significantly different gene delivery efficiencies in vitro. Moreover, we show that the type of PEG derivative used in microbubble formulations greatly influences the acoustic response of microbubbles (i.e., resonance frequency and frequency-dependent attenuation coefficient), thus explaining the differences in gene delivery efficiencies. Our results highlight that changing a single component in the microbubble formulation, i.e., the type of PEG derivative, can improve gene delivery efficiency by 3-fold. This comparative study of microbubbles made with different PEG derivatives may help researchers in designing microbubble formulations for optimal gene delivery.

Predictive value of the monocyte count for determining the risk of postoperative moderate-to-severe ARDS in patients undergoing one-lung ventilation during radical treatment of esophageal cancer

Background

This study aimed to screen for risk factors and to assess the predictive value of the monocyte count for the development of moderate-to-severe acute respiratory distress syndrome (ARDS) in patients undergoing one-lung ventilation (OLV) during radical surgery for esophageal cancer.

Methods

In this retrospective study, patients with esophageal cancer admitted to the Department of Thoracic Surgery of Wuxi People's Hospital between January 2017 and January 2021 were selected. Demographic, preoperative, intraoperative, and postoperative (within 2 h) data were collected. Patients were categorized into moderate-to-severe ARDS and non-moderate-to-severe ARDS groups. Multifactorial logistic regression, receiver operating characteristic (ROC), curve-fitting, and Spearman correlation analysis were used to analyze the data.

Results

After screening, 255 patients were enrolled, with 18% in moderate-to-severe ARDS group. Regression analysis revealed that postoperative monocyte count was an independent predictor for severe ARDS after surgery (OR = 2.916, 95% CI: 1.082-7.863, p < 0.05). The optimal cut-off value of postoperative monocyte count in predicting moderate-to-severe ARDS was 0.56 × 109/L (AUC = 0.708) with a sensitivity of 67.4% and a specificity of 66.5%. The difference of predictive value between postoperative monocyte count and prediction model (AUC = 0.760) was not statistically significant (p = 0.142). Additionally, a nonlinear connection between postoperative monocyte count and severe ARDS was found using curve fitting.

Conclusion

The postoperative monocyte count is an ideal predictor of postoperative moderate-to-severe ARDS in this patient population and can be used for the early diagnosis of patients with severe postoperative ARDS.

Alternative Strategies for Delivering Immunotherapeutics Targeting the PD-1/PD-L1 Immune Checkpoint in Cancer

The programmed death-1/programmed death-ligand 1 (PD-1/PD-L1) immune checkpoint constitutes an inhibitory pathway best known for its regulation of cluster of differentiation 8 (CD8)+ T cell-mediated immune responses. Engagement of PD-L1 with PD-1 expressed on CD8+ T cells activates downstream signaling pathways that culminate in T cell exhaustion and/or apoptosis. Physiologically, these immunosuppressive effects exist to prevent autoimmunity, but cancer cells exploit this pathway by overexpressing PD-L1 to facilitate immune escape. Intravenously (IV) administered immune checkpoint inhibitors (ICIs) that block the interaction between PD-1/PD-L1 have achieved great success in reversing T cell exhaustion and promoting tumor regression in various malignancies. However, these ICIs can cause immune-related adverse events (irAEs) due to off-tumor toxicities which limits their therapeutic potential. Therefore, considerable effort has been channeled into exploring alternative delivery strategies that enhance tumor-directed delivery of PD-1/PD-L1 ICIs and reduce irAEs. Here, we briefly describe PD-1/PD-L1-targeted cancer immunotherapy and associated irAEs. We then provide a detailed review of alternative delivery approaches, including locoregional (LDD)-, oncolytic virus (OV)-, nanoparticle (NP)-, and ultrasound and microbubble (USMB)-mediated delivery that are currently under investigation for enhancing tumor-specific delivery to minimize toxic off-tumor effects. We conclude with a commentary on key challenges associated with these delivery methods and potential strategies to mitigate them.

MOFs for next-generation cancer therapeutics through a biophysical approach-a review

Metal-organic frameworks (MOFs) have emerged as promising nanocarriers for cancer treatment due to their unique properties. Featuring high porosity, extensive surface area, chemical stability, and good biocompatibility, MOFs are ideal for efficient drug delivery, targeted therapy, and controlled release. They can be designed to target specific cellular organelles to disrupt metabolic processes in cancer cells. Additionally, functionalization with enzymes mimics their catalytic activity, enhancing photodynamic therapy and overcoming apoptosis resistance in cancer cells. The controllable and regular structure of MOFs, along with their tumor microenvironment responsiveness, make them promising nanocarriers for anticancer drugs. These carriers can effectively deliver a wide range of drugs with improved bioavailability, controlled release rate, and targeted delivery efficiency compared to alternatives. In this article, we review both experimental and computational studies focusing on the interaction between MOFs and drug, explicating the release mechanisms and stability in physiological conditions. Notably, we explore the relationship between MOF structure and its ability to damage cancer cells, elucidating why MOFs are excellent candidates for bio-applicability. By understanding the problem and exploring potential solutions, this review provides insights into the future directions for harnessing the full potential of MOFs, ultimately leading to improved therapeutic outcomes in cancer treatment.

Acute lung injury: a view from the perspective of necroptosis

BACKGROUND

ALI/ARDS is a syndrome of acute onset characterized by progressive hypoxemia and noncardiogenic pulmonary edema as the primary clinical manifestations. Necroptosis is a form of programmed cell necrosis that is precisely regulated by molecular signals. This process is characterized by organelle swelling and membrane rupture, is highly immunogenic, involves extensive crosstalk with various cellular stress mechanisms, and is significantly implicated in the onset and progression of ALI/ARDS.

METHODS

The current body of literature on necroptosis and ALI/ARDS was thoroughly reviewed. Initially, an overview of the molecular mechanism of necroptosis was provided, followed by an examination of its interactions with apoptosis, pyroptosis, autophagy, ferroptosis, PANOptosis, and NETosis. Subsequently, the involvement of necroptosis in various stages of ALI/ARDS progression was delineated. Lastly, drugs targeting necroptosis, biomarkers, and current obstacles were presented.

CONCLUSION

Necroptosis plays an important role in the progression of ALI/ARDS. However, since ALI/ARDS is a clinical syndrome caused by a variety of mechanisms, we emphasize that while focusing on necroptosis, it may be more beneficial to treat ALI/ARDS by collaborating with other mechanisms.

Recent advances of ultrasound-responsive nanosystems in tumor immunotherapy

Immunotherapy has revolutionized cancer treatment by boosting the immune system and preventing disease escape mechanisms. Despite its potential, challenges like limited response rates and adverse immune effects impede its widespread clinical adoption. Ultrasound (US), known for its safety and effectiveness in tumor diagnosis and therapy, has been shown to significantly enhance immunotherapy when used with nanosystems. High-intensity focused ultrasound (HIFU) can obliterate tumor cells and elicit immune reactions through the creation of immunogenic debris. Low-intensity focused ultrasound (LIFU) bolsters tumor immunosuppression and mitigates metastasis risk by concentrating dendritic cells. Ultrasonic cavitation (UC) produces microbubbles that can transport immune enhancers directly, thus strengthening the immune response and therapeutic impact. Sonodynamic therapy (SDT) merges nanotechnology with immunotherapy, using specialized sonosensitizers to kill cancer cells and stimulate immune responses, increasing treatment success. This review discusses the integration of ultrasound-responsive nanosystems in tumor immunotherapy, exploring future opportunities and current hurdles.

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.

Low-frequency ultrasound for pulmonary hypertension therapy

BACKGROUND

Currently, there are no reliable clinical tools that allow non-invasive therapeutic support for patients with pulmonary arterial hypertension. This study aims to propose a low-frequency ultrasound device for pulmonary hypertension therapy and to demonstrate its potential.

METHODS

A novel low-frequency ultrasound transducer has been developed. Due to its structural properties, it is excited by higher vibrational modes, which generate a signal capable of deeply penetrating biological tissues. A methodology for the artificial induction of pulmonary hypertension in sheep and for the assessment of lung physiological parameters such as blood oxygen concentration, pulse rate, and pulmonary blood pressure has been proposed.

RESULTS

The results showed that exposure of the lungs to low-frequency ultrasound changed physiological parameters such as blood oxygen concentration, pulse rate and blood pressure. These parameters are most closely related to indicators of pulmonary hypertension (PH). The ultrasound exposure increased blood oxygen concentration over a 7-min period, while pulse rate and pulmonary blood pressure decreased over the same period. In anaesthetised sheep exposed to low-frequency ultrasound, a 10% increase in SpO2, a 10% decrease in pulse rate and an approximate 13% decrease in blood pressure were observed within 7 min.

CONCLUSIONS

The research findings demonstrate the therapeutic efficiency of low-frequency ultrasound on hypertensive lungs, while also revealing insights into the physiological aspects of gas exchange within the pulmonary system.

Smart stimuli-responsive drug delivery systems in spotlight of COVID-19

The world has been dealing with a novel severe acute respiratory syndrome (SARS-CoV-2) since the end of 2019, which threatens the lives of many people worldwide. COVID-19 causes respiratory infection with different symptoms, from sneezing and coughing to pneumonia and sometimes gastric symptoms. Researchers worldwide are actively developing novel drug delivery systems (DDSs), such as stimuli-responsive DDSs. The ability of these carriers to respond to external/internal and even multiple stimuli is essential in creating "smart" DDS that can effectively control dosage, sustained release, individual variations, and targeted delivery. To conduct a comprehensive literature survey for this article, the terms "Stimuli-responsive", "COVID-19″ and "Drug delivery" were searched on databases/search engines like "Google Scholar", "NCBI", "PubMed", and "Science Direct". Many different types of DDSs have been proposed, including those responsive to various exogenous (light, heat, ultrasound and magnetic field) or endogenous (microenvironmental changes in pH, ROS and enzymes) stimuli. Despite significant progress in DDS research, several challenging issues must be addressed to fill the gaps in the literature. Therefore, this study reviews the drug release mechanisms and applications of endogenous/exogenous stimuli-responsive DDSs while also exploring their potential with respect to COVID-19.

Delivery systems of therapeutic nucleic acids for the treatment of acute lung injury/acute respiratory distress syndrome

Acute lung injury (ALI)/ acute respiratory distress syndrome (ARDS) is a devastating inflammatory lung disease with a high mortality rate. ALI/ARDS is induced by various causes, including sepsis, infections, thoracic trauma, and inhalation of toxic reagents. Corona virus infection disease-19 (COVID-19) is also a major cause of ALI/ARDS. ALI/ARDS is characterized by inflammatory injury and increased vascular permeability, resulting in lung edema and hypoxemia. Currently available treatments for ALI/ARDS are limited, but do include mechanical ventilation for gas exchange and treatments supportive of reduction of severe symptoms. Anti-inflammatory drugs such as corticosteroids have been suggested, but their clinical effects are controversial with possible side-effects. Therefore, novel treatment modalities have been developed for ALI/ARDS, including therapeutic nucleic acids. Two classes of therapeutic nucleic acids are in use. The first constitutes knock-in genes for encoding therapeutic proteins such as heme oxygenase-1 (HO-1) and adiponectin (APN) at the site of disease. The other is oligonucleotides such as small interfering RNAs and antisense oligonucleotides for knock-down expression of target genes. Carriers have been developed for efficient delivery for therapeutic nucleic acids into the lungs based on the characteristics of the nucleic acids, administration routes, and targeting cells. In this review, ALI/ARDS gene therapy is discussed mainly in terms of delivery systems. The pathophysiology of ALI/ARDS, therapeutic genes, and their delivery strategies are presented for development of ALI/ARDS gene therapy. The current progress suggests that selected and appropriate delivery systems of therapeutic nucleic acids into the lungs may be useful for the treatment of ALI/ARDS.

Precision Medicine Using Simultaneous Monitoring and Assessment with Imaging and Biomarkers to Manage Mechanical Ventilation in ARDS

Acute respiratory distress syndrome (ARDS) has a ~ 40% mortality rate with an increasing prevalence exacerbated by the COVID-19 pandemic. Mechanical ventilation is the primary means for life-saving support to buy time for lung healing in ARDS patients, however, it can also lead to ventilator-induced lung injury (VILI). Effective strategies to reduce or prevent VILI are necessary but are not currently delivered. Therefore, we aim at evaluating the current imaging technologies to visualize where pressure and volume being delivered to the lung during mechanical ventilation; and combining plasma biomarkers to guide management of mechanical ventilation. We searched PubMed and Medline using keywords and analyzed the literature, including both animal models and human studies, to examine the independent use of computed tomography (CT) to evaluate lung mechanics, electrical impedance tomography (EIT) to guide ventilation, ultrasound to monitor lung injury, and plasma biomarkers to indicate status of lung pathophysiology. This investigation has led to our proposal of the combination of imaging and biomarkers to precisely deliver mechanical ventilation to improve patient outcomes in ARDS.

Bubble-Based Drug Delivery Systems: Next-Generation Diagnosis to Therapy

Current radiologic and medication administration is systematic and has widespread side effects; however, the administration of microbubbles and nanobubbles (MNBs) has the possibility to provide therapeutic and diagnostic information without the same ramifications. Microbubbles (MBs), for instance, have been used for ultrasound (US) imaging due to their ability to remain in vessels when exposed to ultrasonic waves. On the other hand, nanobubbles (NBs) can be used for further therapeutic benefits, including chronic treatments for osteoporosis and cancer, gene delivery, and treatment for acute conditions, such as brain infections and urinary tract infections (UTIs). Clinical trials are also being conducted for different administrations and utilizations of MNBs. Overall, there are large horizons for the benefits of MNBs in radiology, general medicine, surgery, and many more medical applications. As such, this review aims to evaluate the most recent publications from 2016 to 2022 to report the current uses and innovations for MNBs.

A systematic review of ultrasound-mediated drug delivery to the eye and critical insights to facilitate a timely path to the clinic

Ultrasound has long been identified as a promising, non-invasive modality for improving ocular drug delivery across a range of indications. Yet, with 20 years of learnings behind us, clinical translation remains limited. To help address this, and in accordance with PRISMA guidelines, the various mechanisms of ultrasound-mediated ocular drug delivery have been appraised, ranging from first principles to emergent applications spanning both ex vivo and in vivo models. The heterogeneity of study methods precluded meta-analysis, however an extensive characterisation of the included studies allowed for semi-quantitative and qualitative assessments. Methods: In this review, we reflected on study quality of reporting, and risk of bias (RoB) using the latest Animal Research: Reporting of In Vivo Experiments (ARRIVE 2.0) guidelines, alongside the Systematic Review Centre for Laboratory animal Experimentation (SYRCLE) RoB tools. Literature studies from 2002 to 2022 were initially characterised according to methods of ultrasound application, ultrasound parameters applied, animal models employed, as well as safety and efficacy assessments. This exercise contributed to developing a comprehensive understanding of the current state of play within ultrasound-mediated ocular drug delivery. The results were then synthesised and processed into a guide to aid future study design, with the goal of improving the reliability of data, and to support efficient and timely translation to the clinic. Results: Key attributes identified as hindering translation included: poor reporting quality and high RoB, skewed use of animals unrepresentative of the human eye, and the over reliance of reductionist safety assessments. Ex vivo modelling studies were often unable to have comprehensive safety assessments performed on them, which are imperative to determining treatment safety, and represent a pre-requisite for clinical translation. Conclusion: With the use of our synthesised guide, and a thorough understanding of the underlying physicochemical interactions between ultrasound and ocular biology provided herein, this review offers a firm foundation on which future studies should ideally be built, such that ultrasound-mediated ocular drug delivery can be translated from concept to the coalface where it can provide immense clinical benefit.

Plug and Pop: A 3D-Printed, Modular Platform for Drug Delivery Using Clinical Ultrasound and Microbubbles

Targeted drug and gene delivery using ultrasound and microbubbles (USMB) has the potential to treat several diseases. In vitro investigation of USMB-mediated delivery is of prime importance prior to in vivo studies because it is cost-efficient and allows for the rapid optimization of experimental parameters. Most in vitro USMB studies are carried out with non-clinical, research-grade ultrasound systems, which are not approved for clinical use and are difficult to replicate by other labs. A standardized, low-cost, and easy-to-use in vitro experimental setup using a clinical ultrasound system would facilitate the eventual translation of the technology to the bedside. In this paper, we report a modular 3D-printed experimental setup using a clinical ultrasound transducer that can be used to study USMB-mediated drug delivery. We demonstrate its utility for optimizing various cargo delivery parameters in the HEK293 cell line, as well as for the CMT167 lung carcinoma cell line, using dextran as a model drug. We found that the proportion of dextran-positive cells increases with increasing mechanical index and ultrasound treatment time and decreases with increasing pulse interval (PI). We also observed that dextran delivery is most efficient for a narrow range of microbubble concentrations.

Controlled Shrinkage of Microfluidically Generated Microbubbles by Tuning Lipid Concentration

Monodisperse microbubbles with diameters less than 10 μm are desirable in several ultrasound imaging and therapeutic delivery applications. However, conventional approaches to synthesize microbubbles, which are usually agitation-based, produce polydisperse bubbles that are less desirable because of their heterogeneous response when exposed to an ultrasound field. Microfluidics technology has the unique advantage of generating size-controlled monodisperse microbubbles, and it is now well established that the diameter of microfluidically made microbubbles can be tuned by varying the liquid flow rate, gas pressure, and dimensions of the microfluidic channel. It is also observed that once the microbubbles form, the bubbles shrink and eventually stabilize to a quasi-equilibrium diameter, and that the rate of stabilization is related to the lipid solution. However, how the lipid solution concentration affects the degree of bubble shrinkage, and the stable size of microbubbles, has not been thoroughly examined. Here, we investigate whether and how the lipid concentration affects the degree of microbubble shrinkage. Namely, we utilize a flow-focusing microfluidic geometry to generate monodisperse bubbles, and observe the effect of gas composition (2.5, 1.42, and 0.17 wt % octafluoropropane in nitrogen) and lipid concentration (1-16 mg/mL) on the degree of microbubble shrinkage. For the lipid system and gas utilized in these experiments, we observe a monotonic increase in the degree of microbubble shrinkage with decreasing lipid concentration, and no dependency on the gas composition. We hypothesize that the degree of shrinkage is related to lipid concentration by the self-assembly of lipids on the gas-liquid interface during bubble generation and subsequent lipid packing on the interface during shrinkage, which is arrested when a maximum packing density is achieved. We anticipate that this approach for creating and tuning the size of monodisperse microbubbles will find utility in biomedical applications, such as contrast-enhanced ultrasound imaging and ultrasound-triggered gene delivery.

Transcranial ultrasound stimulation applied in ischemic stroke rehabilitation: A review

Ischemic stroke is a serious medical condition that is caused by cerebral vascular occlusion and leads to neurological dysfunction. After stroke, patients suffer from long-term sensory, motor and cognitive impairment. Non-invasive neuromodulation technology has been widely studied in the field of stroke rehabilitation. Transcranial ultrasound stimulation (TUS), as a safe and non-invasive technique with deep penetration ability and a tiny focus, is an emerging technology. It can produce mechanical and thermal effects by delivering sound waves to brain tissue that can induce the production of neurotrophic factors (NFs) in the brain, and reduce cell apoptosis and the inflammatory response. TUS, which involves application of an acoustic wave, can also dissolve blood clots and be used to deliver therapeutic drugs to the ischemic region. TUS has great potential in the treatment of ischemic stroke. Future advancements in imaging and parameter optimization will improve the safety and efficacy of this technology in the treatment of ischemic stroke.

Endothelial Dysfunction after Hematopoietic Stem Cell Transplantation: A Review Based on Physiopathology

Endothelial dysfunction (ED) is frequently encountered in transplant medicine. ED is an argument of high complexity, and its understanding requires a wide spectrum of knowledge based on many fields of basic sciences such as molecular biology, immunology, and pathology. After hematopoietic stem cell transplantation (HSCT), ED participates in the pathogenesis of various complications such as sinusoidal obstruction syndrome/veno-occlusive disease (SOS/VOD), graft-versus-host disease (GVHD), transplant-associated thrombotic microangiopathy (TA-TMA), idiopathic pneumonia syndrome (IPS), capillary leak syndrome (CLS), and engraftment syndrome (ES). In the first part of the present manuscript, we briefly review some biological aspects of factors involved in ED: adhesion molecules, cytokines, Toll-like receptors, complement, angiopoietin-1, angiopoietin-2, thrombomodulin, high-mobility group B-1 protein, nitric oxide, glycocalyx, coagulation cascade. In the second part, we review the abnormalities of these factors found in the ED complications associated with HSCT. In the third part, a review of agents used in the treatment of ED after HSCT is presented.

Recent ultrasound advancements for the manipulation of nanobiomaterials and nanoformulations for drug delivery

Recent advances in ultrasound (US) have shown its great potential in biomedical applications as diagnostic and therapeutic tools. The coupling of US-assisted drug delivery systems with nanobiomaterials possessing tailor-made functions has been shown to remove the limitations of conventional drug delivery systems. The low-frequency US has significantly enhanced the targeted drug delivery effect and efficacy, reducing limitations posed by conventional treatments such as a limited therapeutic window. The acoustic cavitation effect induced by the US-mediated microbubbles (MBs) has been reported to replace drugs in certain acute diseases such as ischemic stroke. This review briefly discusses the US principles, with particular attention to the recent advancements in drug delivery applications. Furthermore, US-assisted drug delivery coupled with nanobiomaterials to treat different diseases (cancer, neurodegenerative disease, diabetes, thrombosis, and COVID-19) are discussed in detail. Finally, this review covers the future perspectives and challenges on the applications of US-mediated nanobiomaterials.