Cationic gas-filled microbubbles for ultrasound-based nucleic acids delivery

Potentiation of anti-angiogenic eNOS-siRNA transfection by ultrasound-mediated microbubble destruction in ex vivo rat aortic rings

Nitric oxide (NO) regulates vascular homeostasis and plays a key role in revascularization and angiogenesis. The endothelial nitric oxide synthase (eNOS) enzyme catalyzes NO production in endothelial cells. Overexpression of the eNOS gene has been implicated in pathologies with dysfunctional angiogenic processes, such as cancer. Therefore, modulating eNOS gene expression using small interfering RNAs (siRNAs) represents a viable strategy for antitumor therapy. siRNAs are highly specific to the target gene, thus reducing off-target effects. Given the widespread distribution of endothelium and the crucial physiological role of eNOS, localized delivery of nucleic acid to the affected area is essential. Therefore, the development of an efficient eNOS-siRNA delivery carrier capable of controlled release is imperative for targeting specific vascular regions, particularly those associated with tumor vascular growth. Thus, this study aims to utilize ultrasound-mediated microbubble destruction (UMMD) technology with cationic microbubbles loaded with eNOS-siRNA to enhance transfection efficiency and improve siRNA delivery, thereby preventing sprouting angiogenesis. The efficiency of eNOS-siRNA transfection facilitated by UMMD was assessed using bEnd.3 cells. Synthesis of nitric oxide and eNOS protein expression were also evaluated. The silencing of eNOS gene in a model of angiogenesis was assayed using the rat aortic ring assay. The results showed that from 6 to 24 h, the transfection of fluorescent siRNA with UMMD was twice as high as that of lipofection. Moreover, transfection of eNOS-siRNA with UMMD enhanced the knockdown level (65.40 ± 4.50%) compared to lipofectamine (40 ± 1.70%). Silencing of eNOS gene with UMMD required less amount of eNOS-siRNA (42 ng) to decrease the level of eNOS protein expression (52.30 ± 0.08%) to the same extent as 79 ng of eNOS-siRNA using lipofectamine (56.30 ± 0.10%). NO production assisted by UMMD was reduced by 81% compared to 67% reduction transfecting with lipofectamine. This diminished NO production led to higher attenuation of aortic ring outgrowth. Three-fold reduction compared to lipofectamine transfection. In conclusion, we propose the combination of eNOS-siRNA and UMMD as an efficient, safe, non-viral nucleic acid transfection strategy for inhibition of tumor progression.

FUS-mediated BBB opening leads to transient perfusion decrease and inflammation without acute or chronic brain lesion

Impact: The permeabilization of the BBB to deliver therapeutics with MR-guided FUS redefines therapeutic strategies as it improves patient outcomes. To ensure the best translation towards clinical treatment, the evaluation of hemodynamic modifications in the CNS is necessary to refine treatment parameters. Methods: MR-guided FUS was applied at 1.5 MHz with a 50 ms burst every 1 s to open the BBB. CBF, BVf and ADC parameters were monitored with MRI. Cavitation was monitored with a PCD during the FUS sequence and classified with the IUD index into three cavitation levels. We distinctly applied the FUS in the cortex or the striatum. After the BBB permeabilization, neuroinflammation markers were quantified longitudinally. Results: The BBB was successfully opened in all animals in this study and only one animal was classified as "hard" and excluded from the rest of the study. 30 min after FUS-induced BBB opening in the cortex, we measured a 54% drop in CBF and a 13% drop in BVf compared to the contralateral side. After permeabilization of the striatum, a 38% drop in CBF and a 15% drop in BVf were measured. CBF values rapidly returned to baseline, and 90 min after BBB opening, no significant differences were observed. We quantified the subsequent neuroinflammation, noting a significant increase in astrocytic recruitment at 2 days and microglial activation at 1 day after FUS. After 7 days, no more inflammation was visible in the brain. Conclusion: FUS-induced BBB opening transiently modifies hemodynamic parameters such as CBF and BVf, suggesting limited nutrients and oxygen supply to the CNS in the hour following the procedure.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Nanobubble-mediated cancer cell sonoporation using low-frequency ultrasound

Ultrasound insonation of microbubbles can form transient pores in cell membranes that enable the delivery of non-permeable extracellular molecules to the cells. Reducing the size of microbubble contrast agents to the nanometer range could facilitate cancer sonoporation. This size reduction can enhance the extravasation of nanobubbles into tumors after an intravenous injection, thus providing a noninvasive sonoporation platform. However, drug delivery efficacy depends on the oscillations of the bubbles, the ultrasound parameters and the size of the target compared to the membrane pores. The formation of large pores is advantageous for the delivery of large molecules, however the small size of the nanobubbles limit the bioeffects when operating near the nanobubble resonance frequency at the MHz range. Here, we show that by coupling nanobubbles with 250 kHz low frequency ultrasound, high amplitude oscillations can be achieved, which facilitate low energy sonoporation of cancer cells. This is beneficial both for increasing the uptake of a specific molecule and to improve large molecule delivery. The method was optimized for the delivery of four fluorescent molecules ranging in size from 1.2 to 70 kDa to breast cancer cells, while comparing the results to targeted microbubbles. Depending on the fluorescent molecule size, the optimal ultrasound peak negative pressure was found to range between 300 and 500 kPa. Increasing the pressure to 800 kPa reduced the fraction of fluorescent cells for all molecules sizes. The optimal uptake for the smaller molecule size of 4 kDa resulted in a fraction of 19.9 ± 1.8% of fluorescent cells, whereas delivery of 20 kDa and 70 kDa molecules yielded 14 ± 0.8% and 4.1 ± 1.1%, respectively. These values were similar to targeted microbubble-mediated sonoporation, suggesting that nanobubbles can serve as noninvasive sonoporation agents with a similar potency, and at a reduced bubble size. The nanobubbles effectively reduced cell viability and may thus potentially reduce the tumor burden, which is crucial for the success of cancer treatment. This method provides a non-invasive and low-energy tumor sonoporation theranostic platform, which can be combined with other therapies to maximize the therapeutic benefits of cancer treatment or be harnessed in gene therapy applications.

Intracellular protein delivery: New insights into the therapeutic applications and emerging technologies

The inability to cross the plasma membranes traditionally limited the therapeutic use of recombinant proteins. However, in the last two decades, novel technologies made delivering proteins inside the cells possible. This allowed researchers to unlock intracellular targets, once considered 'undruggable', bringing a new research area to emerge. Protein transfection systems display a large potential in a plethora of applications. However, their modality of action is often unclear, and cytotoxic effects are elevated, whereas experimental conditions to increase transfection efficacy and cell viability still need to be identified. Furthermore, technical complexity often limits in vivo experimentation, while challenging industrial and clinical translation. This review highlights the applications of protein transfection technologies, and then critically discuss the current methodologies and their limitations. Physical membrane perforation systems are compared to systems exploiting cellular endocytosis. Research evidence of the existence of either extracellular vesicles (EVs) or cell-penetrating peptides (CPPs)- based systems, that circumvent the endosomal systems is critically analysed. Commercial systems, novel solid-phase reverse protein transfection systems, and engineered living intracellular bacteria-based mechanisms are finally described. This review ultimately aims at finding new methodologies and possible applications of protein transfection systems, while helping the development of an evidence-based research approach.

CFTR and dystrophin encoding plasmids carrying both luciferase reporter gene, nuclear import specific sequences and triple helix sites

Duchenne Muscular Dystrophy and Cystic Fibrosis are two major monogenetic diseases which could be treated by non-viral gene therapy. For this purpose, plasmid DNA (pDNA) coding for the functional genes requires its equipment with signal molecules favouring its intracellular trafficking and delivery in the nucleus of the target cells. Here, two novel constructions of large pDNAs encoding the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) and full-length dystrophin (DYS) genes are reported. The expression of CFTR and DYS genes are driven respectively by the hCEF1 airway epithelial cells and spc5-12 muscle cells specific promoter. Those pDNAs encode also the luciferase reporter gene driven by the CMV promoter to evaluate gene delivery in animals by bioluminescence. In addition, oligopurine • oligopyrimidine sequences are inserted to enable equipment of pDNAs with peptides conjugated with a triple helix forming oligonucleotide (TFO). Furthermore, specific κB sequences are also inserted to promote their NFκB-mediated nuclear import. pDNA constructions are reported; transfection efficiency, tissue specific expression of CFTR and dystrophin in target cells, and triple helix formation are demonstrated. These plasmids are tools of interest to develop non-viral gene therapy of Cystic Fibrosis and Duchenne Muscular Dystrophy.

Non-viral nitric oxide-based gene therapy improves perfusion and liposomal doxorubicin sonopermeation in neuroblastoma models

Neuroblastoma (NB) is a pediatric malignancy that accounts for 15% of cancer-related childhood mortality. High-risk NB requires an aggressive chemoradiotherapy regimen that causes significant off-target toxicity. Despite this invasive treatment, many patients either relapse or do not respond adequately. Recent studies suggest that improving tumor perfusion can enhance drug accumulation and distribution within the tumor tissue, potentially augmenting treatment effects without inflicting systemic toxicity. Accordingly, methods that transiently increase tumor perfusion prior to treatment may help combat this disease. Here, we show the use of gene therapy to confer inducible nitric oxide synthase (iNOS) expression solely in the tumor space, using focused ultrasound targeting. NOS catalyzes the reaction that generates nitric oxide (NO), a potent endogenous vasodilator. This study reports the development of a targeted non-viral image-guided platform to deliver iNOS-expressing plasmid DNA (pDNA) to vascular endothelial cells encasing tumor blood vessels. Following transfection, longitudinal quantitative contrast-enhanced ultrasound (qCEUS) imaging revealed an increase in tumor perfusion over 72 h, attributed to elevated intratumoral iNOS expression. Methods: To construct a gene delivery vector, cationic ultrasound-responsive agents (known as "microbubbles") were employed to carry pDNA in circulation and transfect tumor vascular endothelial cells in vivo using focused ultrasound (FUS) energy. This was followed by liposomal doxorubicin (L-DOX) treatment. The post-transfection tumor response was monitored longitudinally using qCEUS imaging to determine relative changes in blood volumes and perfusion rates. After therapy, ex vivo analysis of tumors was performed to examine the bioeffects associated with iNOS expression. Results: By combining FUS therapy with cationic ultrasound contrast agents (UCAs), we achieved selective intratumoral transfection of pDNA encoding the iNOS enzyme. While transitory, the degree of expression was sufficient to induce significant increases in tumoral perfusion, to appreciably enhance the chemotherapeutic payload and to extend survival time in an orthotopic xenograft model. Conclusion: We have demonstrated the ability of a novel targeted non-viral gene therapy strategy to enhance tumor perfusion and improve L-DOX delivery to NB xenografts. While our results demonstrate that transiently increasing tumor perfusion improves liposome-encapsulated chemotherapeutic uptake and distribution, we expect that our iNOS gene delivery paradigm can also significantly improve radio and immunotherapies by increasing the delivery of radiosensitizers and immunomodulators, potentially improving upon current NB treatment without concomitant adverse effects. Our findings further suggest that qCEUS imaging can effectively monitor changes in tumor perfusion in vivo, allowing the identification of an ideal time-point to administer therapy.

Cationic Microbubbles for Non-Selective Binding of Cavitation Nuclei to Bacterial Biofilms

The presence of multi-drug resistant biofilms in chronic, persistent infections is a major barrier to successful clinical outcomes of therapy. The production of an extracellular matrix is a characteristic of the biofilm phenotype, intrinsically linked to antimicrobial tolerance. The heterogeneity of the extracellular matrix makes it highly dynamic, with substantial differences in composition between biofilms, even in the same species. This variability poses a major challenge in targeting drug delivery systems to biofilms, as there are few elements both suitably conserved and widely expressed across multiple species. However, the presence of extracellular DNA within the extracellular matrix is ubiquitous across species, which alongside bacterial cell components, gives the biofilm its net negative charge. This research aims to develop a means of targeting biofilms to enhance drug delivery by developing a cationic gas-filled microbubble that non-selectively targets the negatively charged biofilm. Cationic and uncharged microbubbles loaded with different gases were formulated and tested to determine their stability, ability to bind to negatively charged artificial substrates, binding strength, and, subsequently, their ability to adhere to biofilms. It was shown that compared to their uncharged counterparts, cationic microbubbles facilitated a significant increase in the number of microbubbles that could both bind and sustain their interaction with biofilms. This work is the first to demonstrate the utility of charged microbubbles for the non-selective targeting of bacterial biofilms, which could be used to significantly enhance stimuli-mediated drug delivery to the bacterial biofilm.

Photoacoustic/ultrasound-guided gene silencing: Multifunctional microbubbles for treating adjuvant-induced arthritis

AIMS

To effectively deliver small interfering RNA (siRNA) to inflammatory tissues for treating rheumatoid arthritis (RA), we developed the multifunctional microbubbles (MBs) to perform photoacoustic/ultrasound-guided gene silencing.

METHODS

Fluorescein amidite (FAM)-labelled tumour necrosis factor-α (TNF-α)-siRNA and cationic MBs were mixed to fabricate FAM-TNF-α-siRNA-cMBs. The cell transfection efficacy of FAM-TNF-α-siRNA-cMBs was evaluated in vitro on RAW264.7 cells. Subsequently, wistar rats with adjuvant-induced arthritis (AIA) were injected intravenously with MBs and simultaneously subjected to low-frequency ultrasound for ultrasound-targeted microbubble destruction (UTMD). Photoacoustic imaging (PAI) was utilized to visualize the distribution of siRNA. And the clinical and pathological changes of AIA rats was estimated.

RESULTS

FAM-TNF-α-siRNA-cMBs were evenly distributed within the RAW264.7 cells and significantly reduced TNF-α mRNA levels of the cells. For AIA rats, the entering and collapsing of MBs was visualized by contrast-enhanced ultrasound (CEUS). Photoacoustic imaging showed markedly enhanced signals following injection, indicating localization of the FAM-labelled siRNA. The articular tissues of the AIA rats treated with TNF-α-siRNA-cMBs and UTMD showed decreased TNF-α expression levels.

CONCLUSIONS

The theranostic MBs exhibited a TNF-α gene silencing effect under the guidance of CEUS and PAI. The theranostic MBs served as vehicles for delivering siRNA as well as contrast agents for CEUS and PAI.

Ultrasound sensitive O2 microbubbles radiosensitize murine breast cancer but lead to higher metastatic spread

The inadequate level of oxygenation in tumors has been shown to correlate not only with greater invasiveness of cancer cells, but also with a reduction in their sensitivity to anticancer therapies. Over the years, many attempts have been made to increase the oxygenation level of cancer, but most of them have been ineffective. We investigated the heterogeneous response of tumor tissue to phospholipid-coated oxygen microbubbles (OMB) in murine tumors in vivo using oxygen and hemoglobin saturation mapping and the influence of OMB treatment on microvasculature, perfusion, and radiotherapy effectiveness. Intravenous administration of OMB followed by ultrasound pulse leads to increased oxygenation of a tumor, found mainly in the vicinity of tumor vessels, while intratumoral delivery resulted in areas of increased pO₂ more evenly distributed within the tumor. Furthermore, hemoglobin contributes little to the increase in tumor oxygenation caused by oxygen microbubbles. Extensive vasculature disruption was observed in the groups treated with both oxygen/nitrogen microbubbles and ultrasound pulse. This therapy also led to a reduction in the coverage of the vessels by pericytes, while the density of the microvessels was unchanged. Radiotherapy with a single dose of 12Gy reduced tumor growth by 50% in all treated groups. Unfortunately, at the same time, the number of macroscopic metastases in the lungs increased significantly after intravenous administration of oxygen/nitrogen microbubbles and the application of an ultrasound pulse. In conclusion, ultrasound-sensitive oxygen microbubbles are effective in delivering oxygen to tumor tissue, thus increasing the effectiveness of radiotherapy. However, cavitation effects and destruction of the integrity of tumor vessels result in greater spread of cancer cells in the host organism.

Janus USPION modular platform (JUMP) for theranostic ultrasound-mediated targeted intratumoral microvascular imaging and DNA/miRNA delivery

Rationale: High mortality in pancreatic cancer (PDAC) and triple negative breast cancer (TNBC) highlight the need to capitalize on nanoscale-design advantages for multifunctional diagnostics and therapies. DNA/RNA-therapies can provide potential breakthroughs, however, to date, there is no FDA-approved systemic delivery system to solid tumors. Methods: Here, we report a Janus-nanoparticle (jNP)-system with modular targeting, payload-delivery, and targeted-imaging capabilities. Our jNP-system consists of 10 nm ultrasmall superparamagnetic iron oxide nanoparticles (USPION) with opposing antibody-targeting and DNA/RNA payload-protecting faces, directionally self-assembled with commercially available zwitterionic microbubbles (MBs) and DNA/RNA payloads. Results: Sonoporation of targeted jNP-payload-MBs delivers functional reporter-DNA imparting tumor-fluorescence, and micro-RNA126 reducing non-druggable KRAS in PDAC-Panc1 and TNBC-MB231 xenografted tumors. The targeting jNP-system enhances ultrasound-imaging of intra-tumoral microvasculature using less MBs/body weight (BW). The jNP-design enhances USPION's T2*-magnetic resonance (MR) and MR-imaging of PDAC-peritoneal metastases using less Fe/BW. Conclusion: Altogether, data advance the asymmetric jNP-design as a potential theranostic Janus-USPION Modular Platform - a JUMP forward.

Smart and Multi-Functional Magnetic Nanoparticles for Cancer Treatment Applications: Clinical Challenges and Future Prospects

Iron oxide nanoparticle (IONPs) have become a subject of interest in various biomedical fields due to their magnetism and biocompatibility. They can be utilized as heat mediators in magnetic hyperthermia (MHT) or as contrast media in magnetic resonance imaging (MRI), and ultrasound (US). In addition, their high drug-loading capacity enabled them to be therapeutic agent transporters for malignancy treatment. Hence, smartening them allows for an intelligent controlled drug release (CDR) and targeted drug delivery (TDD). Smart magnetic nanoparticles (SMNPs) can overcome the impediments faced by classical chemo-treatment strategies, since they can be navigated and release drug via external or internal stimuli. Recently, they have been synchronized with other modalities, e.g., MRI, MHT, US, and for dual/multimodal theranostic applications in a single platform. Herein, we provide an overview of the attributes of MNPs for cancer theranostic application, fabrication procedures, surface coatings, targeting approaches, and recent advancement of SMNPs. Even though MNPs feature numerous privileges over chemotherapy agents, obstacles remain in clinical usage. This review in particular covers the clinical predicaments faced by SMNPs and future research scopes in the field of SMNPs for cancer theranostics.

Ultrafast Microscopy Imaging of Acoustic Cluster Therapy Bubbles: Activation and Oscillation

Acoustic Cluster Therapy (ACT®) is a platform for improving drug delivery and has had promising pre-clinical results. A clinical trial is ongoing. ACT® is based on microclusters of microbubbles-microdroplets that, when sonicated, form a large ACT® bubble. The aim of this study was to obtain new knowledge on the dynamic formation and oscillations of ACT® bubbles by ultrafast optical imaging in a microchannel. The high-speed recordings revealed the microbubble-microdroplet fusion, and the gas in the microbubble acted as a vaporization seed for the microdroplet. Subsequently, the bubble grew by gas diffusion from the surrounding medium and became a large ACT® bubble with a diameter of 5-50 μm. A second ultrasound exposure at lower frequency caused the ACT® bubble to oscillate. The recorded oscillations were compared with simulations using the modified Rayleigh-Plesset equation. A term accounting for the physical boundary imposed by the microchannel wall was included. The recorded oscillation amplitudes were approximately 1-2 µm, hence similar to oscillations of smaller contrast agent microbubbles. These findings, together with our previously reported promising pre-clinical therapeutic results, suggest that these oscillations covering a large part of the vessel wall because of the large bubble volume can substantially improve therapeutic outcome.

Bactericidal and anti-biofilm effects of uncharged and cationic ultrasound-responsive nitric oxide microbubbles on Pseudomonas aeruginosa biofilms

Bacterial biofilms are a major and ongoing concern for public health, featuring both inherited genetic resistance traits and a conferred innate tolerance to traditional antibiotic therapies. Consequently, there is a growing need for novel methods of drug delivery, to increase the efficacy of antimicrobial agents. This research evaluated the anti-biofilm and bactericidal effects of ultrasound responsive gas-microbubbles (MBs) of either air or nitric oxide, using an in vitro Pseudomonas aeruginosa biofilm model grown in artificial wound medium. The four lipid-based MB formulations evaluated were room-air MBs (RAMBs) and nitric oxide MBs (NOMBs) with no electrical charge, as well as cationic (+) RAMBs⁺ and NOMBs⁺. Two principal treatment conditions were used: i) ultrasound stimulated MBs only, and ii) ultrasound stimulated MBs with a sub-inhibitory concentration (4 µg/mL) of the antibiotic gentamicin. The total treatment time was divided into a 60 second passive MB interaction period prior to 40 second ultrasound exposure; each MB formulation was tested in triplicate. Ultrasound stimulated RAMBs and NOMBs without antibiotic achieved reductions in biofilm biomass of 93.3% and 94.0%, respectively. Their bactericidal efficacy however was limited, with a reduction in culturable cells of 26.9% and 65.3%, respectively. NOMBs with sub-inhibitory antibiotic produced the most significant reduction in biofilm biomass, corresponding to a 99.9% (SD ± 5.21%); and a 99.9% (SD ± 0.07%) (3-log) reduction in culturable bacterial cells. Cationic MBs were initially manufactured to promote binding of MBs to negatively charged biofilms, but these formulations also demonstrated intrinsic bactericidal properties. In the absence of antibiotic, the bactericidal efficacy of RAMB⁺ and NOMB⁺ was greater that of uncharged counterparts, reducing culturable cells by 84.7% and 86.1% respectively; increasing to 99.8% when combined with antibiotic. This study thus demonstrates the anti-biofilm and bactericidal utility of ultrasound stimulated MBs, and specifically is the first to demonstrate the efficacy of a NOMB for the dispersal and potentiation of antibiotics against bacterial biofilms in vitro. Importantly the biofilm system and complex growth-medium were selected to recapitulate key morphological features of in vivo biofilms. The results us offer new insight for the development of new clinical treatments, for example, in chronic wounds.

Next-Generation Colloidal Materials for Ultrasound Imaging Applications

Ultrasound has important applications, predominantly in the field of diagnostic imaging. Presently, colloidal systems such as microbubbles, phase-change emulsion droplets and particle systems with acoustic properties and multiresponsiveness are being developed to address typical issues faced when using commercial ultrasound contrast agents, and to extend the utility of such systems to targeted drug delivery and multimodal imaging. Current technologies and increasing research data on the chemistry, physics and materials science of new colloidal systems are also leading to the development of more complex, novel and application-specific colloidal assemblies with ultrasound contrast enhancement and other properties, which could be beneficial for multiple biomedical applications, especially imaging-guided treatments. In this article, we review recent developments in new colloids with applications that use ultrasound contrast enhancement. This work also highlights the emergence of colloidal materials fabricated from or modified with biologically derived and bio-inspired materials, particularly in the form of biopolymers and biomembranes. Challenges, limitations, potential developments and future directions of these next-generation colloidal systems are also presented and discussed.

Selective attachment of a microtubule interacting peptide to plasmid DNA via a triplex forming oligonucleotide for transfection improvement

In nonviral gene therapy approaches, the linkage of signal molecules to plasmid DNA (pDNA) is of interest for guiding its delivery to the nucleus. Here, we report its linkage to a peptide (P_79-98) mediating migration on microtubules by using a triplex-forming oligonucleotide (TFO). pDNA of 5 kbp and 21 kbp containing 6 and 36 oligopurine • oligopyrimidine sites (TH), respectively, inserted outside the luciferase gene sequence were used. TFO with a dibenzocyclooctyl (DBCO) group in 3' end comprising some Bridged Nucleic Acid bases was conjugated by click chemistry with the peptide carrying an azide function in the C-terminal end. We found the formation of 6 and 18 triplex with pDNA of 5 kbp and 21 kbp, respectively. A twofold increase of the transfection efficiency was observed in the hind-limbs upon Hydrodynamic Limb Vein (HLV) injection in mice of naked P_79-98 -pDNA of 21 kbp. This work paves the way for the selective equipping of pDNA with intracellular targeting molecules while preserving the full expression of the encoded gene.

A Gambogic Acid-Loaded Delivery System Mediated by Ultrasound-Targeted Microbubble Destruction: A Promising Therapy Method for Malignant Cerebral Glioma

Background

Purpose

Methods

Results

Conclusion

Nanomaterials as Ultrasound Theragnostic Tools for Heart Disease Treatment/Diagnosis

A variety of different nanomaterials (NMs) such as microbubbles (MBs), nanobubbles (NBs), nanodroplets (NDs), and silica hollow meso-structures have been tested as ultrasound contrast agents for the detection of heart diseases. The inner part of these NMs is made gaseous to yield an ultrasound contrast, which arises from the difference in acoustic impedance between the interior and exterior of such a structure. Furthermore, to specifically achieve a contrast in the diseased heart region (DHR), NMs can be designed to target this region in essentially three different ways (i.e., passively when NMs are small enough to diffuse through the holes of the vessels supplying the DHR, actively by being associated with a ligand that recognizes a receptor of the DHR, or magnetically by applying a magnetic field orientated in the direction of the DHR on a NM responding to such stimulus). The localization and resolution of ultrasound imaging can be further improved by applying ultrasounds in the DHR, by increasing the ultrasound frequency, or by using harmonic, sub-harmonic, or super-resolution imaging. Local imaging can be achieved with other non-gaseous NMs of metallic composition (i.e., essentially made of Au) by using photoacoustic imaging, thus widening the range of NMs usable for cardiac applications. These contrast agents may also have a therapeutic efficacy by carrying/activating/releasing a heart disease drug, by triggering ultrasound targeted microbubble destruction or enhanced cavitation in the DHR, for example, resulting in thrombolysis or helping to prevent heart transplant rejection.

Low-intensity ultrasound promotes uterine involution after cesarean section: the first multicenter, randomized, controlled clinical trial

OBJECTIVE

To evaluate the clinical efficacy and safety of low-intensity ultrasound (LIUS) in promoting uterine involution and relieving postpartum pain.

METHODS

The randomized controlled clinical trial in this study was conducted at five centers in three regions across China from June 2014 to December 2014. A total of 498 subjects were randomly divided into two groups. The LIUS group received ultrasound treatment, and the control group received sham ultrasound treatment. The fundal height and visual analogue scale (VAS) scores of the subjects following cesarean section were recorded separately before and after five treatments. The incidence of adverse events was recorded, while the records on lochia duration were obtained by telephone follow-up. The Full Analysis Set (FAS) comprised all subjects randomized who received at least one treatment. The Per-Protocol Set (PPS) comprised all patients who did not seriously violate the study protocol and had good compliance with complete report forms. Efficacy analyses were performed based on the FAS and PPS. All safety analyses were performed based on the safety set (SS), which included all patients who received at least one treatment.

RESULTS

In the analysis of PPS and FAS, the LIUS group performed better than the control group in reducing the fundal height, shortening the duration of lochia, and relieving postpartum pain, with a significant difference between the two groups (p < 0.0001). In the SS analysis, there were no treatment-related adverse events observed in either group.

CONCLUSIONS

The LIUS therapy is safe and effective, which contributes to uterine involution and the alleviation of postpartum pain.

CMBs carrying PTX and CRISPR/Cas9 targeting C‑erbB‑2 plasmids interfere with endometrial cancer cells

Development of combination therapy to decrease side effects of chemotherapeutic drugs and increase their utilization rate in combination with gene editing is a key research topic in tumor treatment. The present study aimed to investigate the effect of cationic microbubbles (CMBs) carrying paclitaxel (PTX) and C-erbB-2 knockout plasmid on the endometrial cancer cell line HEC-1A and to determine how C-erbB-2 regulates the function of endometrial cancer cells. Cells were treated with CMB, PTX, PTX-CMBs, cationic plasmid-carrying or cationic PTX-carrying plasmid groups. After verifying the most effective combination of PTX-CMBs and plasmids, HEC-1A cells were transfected. Reverse transcription-quantitative (RT-q)PCR and western blotting were used to measure C-erbB-2 and protein expression. After verifying C-erbB-2 knockout, invasion, healing, clone formation and proliferation of HEC-1A cells were assessed. Simultaneously, expression levels of the genes for P21, P27, mammalian target of rapamycin (mTOR), and Bcl-2 associated death promoter (Bad) were measured by RT-qPCR. Compared with the PTX group, CMBs significantly enhanced the absorption efficiency of PTX by HEC-1A cells. C-erbB-2 knockout had an inhibitory effect on the proliferation, migration and invasion of HEC-1A cells; cell proliferation and invasion of the group carrying PTX and plasmids simultaneously were significantly weakened. The C-erbB-2-knockout group exhibited increased expression of P21 and P27. Simultaneously loading PTX and plasmid may be novel combination therapy with great potential. C-erbB-2 may regulate the proliferation of HEC-1A cells by downregulating expression of P21 and P27.

Comprehensive review on ultrasound-responsive theranostic nanomaterials: mechanisms, structures and medical applications

The field of theranostics has been rapidly growing in recent years and nanotechnology has played a major role in this growth. Nanomaterials can be constructed to respond to a variety of different stimuli which can be internal (enzyme activity, redox potential, pH changes, temperature changes) or external (light, heat, magnetic fields, ultrasound). Theranostic nanomaterials can respond by producing an imaging signal and/or a therapeutic effect, which frequently involves cell death. Since ultrasound (US) is already well established as a clinical imaging modality, it is attractive to combine it with rationally designed nanoparticles for theranostics. The mechanisms of US interactions include cavitation microbubbles (MBs), acoustic droplet vaporization, acoustic radiation force, localized thermal effects, reactive oxygen species generation, sonoluminescence, and sonoporation. These effects can result in the release of encapsulated drugs or genes at the site of interest as well as cell death and considerable image enhancement. The present review discusses US-responsive theranostic nanomaterials under the following categories: MBs, micelles, liposomes (conventional and echogenic), niosomes, nanoemulsions, polymeric nanoparticles, chitosan nanocapsules, dendrimers, hydrogels, nanogels, gold nanoparticles, titania nanostructures, carbon nanostructures, mesoporous silica nanoparticles, fuel-free nano/micromotors.

Ultrasound molecular imaging-guided tumor gene therapy through dual-targeted cationic microbubbles

The success of gene therapy depends largely on the development of gene vectors and effective gene delivery systems. It has been demonstrated that cationic microbubbles can be loaded with negatively charged plasmid DNA and thus improve gene transfection efficiency. In this study, we developed dual-targeting cationic microbubbles conjugated with iRGD peptides(Cyclo(Cys-Arg-Gly-Asp-Lys-Gly-Pro-Asp-Cys)) and CCR2 (chemokine (C-C motif) receptor 2) antibodies (MB_iRGD/CCR2) for ultrasound molecular imaging and targeted tumor gene therapy. The ultrasound molecular imaging experiments showed that there were significantly enhanced ultrasound molecular imaging signals in the tumor that received MB_iRGD/CCR2, compared with those that received MB_iRGD, MB_CCR2, or MB_control. As a therapy plasmid, pGPU6/GFP/Neo-shAKT2, carrying an expression cassette for the human AKT2 RNA interference sequence, was used. Our results demonstrated that MB_iRGD/CCR2 had a significantly higher gene transfection efficiency than MB_iRGD, MB_CCR2, or MB_control under ultrasound irradiation, resulting in much lower AKT2 protein expression and stronger tumor growth inhibition effects in vivo and in vitro. In conclusion, our study demonstrated a novel gene delivery system via MB_iRGD/CCR2 for ultrasound molecular-imaging-guided gene therapy of breast cancer.

Downregulating the P2X3 receptor in the carotid body to reduce blood pressure via acoustic gene delivery in canines

The purinergic P2X3 receptor in the carotid body (CB) is considered a new target for treating hypertension, although approaches for targeted regulating P2X3 receptor expression are lacking. Here, we explored the feasibility of targeted P2X3 receptor down-regulation in CBs by localized low-intensity focused ultrasound (LIFU)-mediated gene delivery to reduce the blood pressure. Thirty-two Kunming canines were randomly assigned to the treatment group (n = 14), negative control group (n = 10), LIFU + cationic microbubbles group (n = 4), and LIFU-only group (n = 4). Plasmid-loaded cationic microbubbles were injected and bilateral CBs were irradiated with a LIFU-based transducer. Flow cytometry showed that 33.15% of transfected cells expressed the green fluorescent protein reporter gene. T7 endonuclease I assays showed an insertion-deletion rate of 8.30%. The P2X3 receptor mRNA- and protein-expression levels in CBs decreased by 56.31% and 45.10%, respectively, in the treatment group. Mean systolic (152.5 ± 3.0 vs 138.0 ± 2.9 mm Hg, P = 0.003) and diastolic (97.8 ± 1.5 vs 87.2 ± 2.3 mm Hg, P= 0.002) blood pressures reduced on day 14 in the treatment group, compared with the baseline values, whereas no effects were observed with LIFU treatment or cationic microbubbles injection alone. Canines treated with this strategy exhibited no local or systemic adverse events. Thus, LIFU-mediated gene delivery to CBs successfully modulated CB function and reduced blood pressure in a canine model, suggesting a new possibility for treating hypertension and further clinical translation.

General Characteristics of Microbubble-Adenovirus Vectors Carrying Genes

Introduction

Transferring genes safely, targeting cells and achieving efficient transfection are urgent problems in gene therapy that need to be solved. Combining microbubbles (MBs) and viruses to construct double vectors has become a promising approach for gene delivery. Understanding the characteristic performance of MBs that carry genes is key to promoting effective gene transfer. Therefore, in this study, we constructed MB-adenovirus vectors and discussed their general characteristics.

Methods

We constructed MB-adenovirus vectors carrying the chemokine (C-X-C motif) ligand 12 (Cxcl12) and bone morphogenetic protein-2 (Bmp2) genes (pAd-Cxcl12 and pAd-Bmp2, respectively) to explore the general characteristics of double vectors carrying genes.

Results

The MB-adenovirus vectors had stable physical properties, and no significant differences in diameter, concentration, or pH were noted compared with naked MBs (p > 0.05). Flow cytometry and RT-PCR were used to detect the gene-loading capacity of MBs. The gene-loading efficiency of MBs increased with increasing virus amounts and was highest (91%) when 10.0 µL of virus was added. Beyond 10.0 µL of added virus, the gene-loading efficiency of MBs decreased with the continuous addition of virus. The maximum amounts of pAd-Cxcl12 and pAd-Bmp2 in 100 µL of MBs were approximately 14 and 10 µL, respectively.

Conclusions

This study indicates that addition of an inappropriate viral load will result in low MB loading efficiency, and the maximum amount of genes loaded by MBs may differ based on the genes carried by the virus.

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

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

Ultrasound-responsive lipid microbubbles for drug delivery: A review of preparation techniques to optimise formulation size, stability and drug loading

Lipid-shelled microbubbles have received extensive interest to enhance ultrasound-responsive drug delivery outcomes due to their high biocompatibility. While therapeutic effectiveness of microbubbles is well established, there remain limitations in sample homogeneity, stability profile and drug loading properties which restrict these formulations from seeing widespread use in the clinical setting. In this review, we evaluate and discuss the most encouraging leads in lipid microbubble design and optimisation. We examine current applications in drug delivery for the systems and subsequently detail shell compositions and preparation strategies that improve monodispersity while retaining ultrasound responsiveness. We review how excipients and storage techniques help maximise stability and introduce different characterisation and drug loading techniques and evaluate their impact on formulation performance. The review concludes with current quality control measures in place to ensure lipid microbubbles can be reproducibly used in drug delivery.

Low-frequency ultrasound-mediated cytokine transfection enhances T cell recruitment at local and distant tumor sites

Robust cytotoxic T cell infiltration has proven to be difficult to achieve in solid tumors. We set out to develop a flexible protocol to efficiently transfect tumor and stromal cells to produce immune-activating cytokines, and thus enhance T cell infiltration while debulking tumor mass. By combining ultrasound with tumor-targeted microbubbles, membrane pores are created and facilitate a controllable and local transfection. Here, we applied a substantially lower transmission frequency (250 kHz) than applied previously. The resulting microbubble oscillation was significantly enhanced, reaching an effective expansion ratio of 35 for a peak negative pressure of 500 kPa in vitro. Combining low-frequency ultrasound with tumor-targeted microbubbles and a DNA plasmid construct, 20% of tumor cells remained viable, and ∼20% of these remaining cells were transfected with a reporter gene both in vitro and in vivo. The majority of cells transfected in vivo were mucin 1+/CD45- tumor cells. Tumor and stromal cells were then transfected with plasmid DNA encoding IFN-β, producing 150 pg/106 cells in vitro, a 150-fold increase compared to no-ultrasound or no-plasmid controls and a 50-fold increase compared to treatment with targeted microbubbles and ultrasound (without IFN-β). This enhancement in secretion exceeds previously reported fourfold to fivefold increases with other in vitro treatments. Combined with intraperitoneal administration of checkpoint inhibition, a single application of IFN-β plasmid transfection reduced tumor growth in vivo and recruited efficacious immune cells at both the local and distant tumor sites.

miR‑378 in combination with ultrasonic irradiation and SonoVue microbubbles transfection inhibits hepatoma cell growth

Ultrasonic microbubbles in combination with microRNA (miRNAs/miRs) exhibited promising effects on cancer treatments. The aim was to investigate the role of miR-378 in hepatoma cells and the efficiency of it in combination with ultrasonic irradiation and SonoVue^® microbubbles method for cell transfection. HuH-7, Hep3B and SK-Hep1 cells were transfected with an miR-378 mimic using only Lipofectamine^® 3000 or combined with SonoVue microbubbles and ultrasonic irradiation at 0.5 W/cm² for 30 sec. mRNAs and protein levels of Cyclin D1, Bcl-2, Bax, Akt, p53 and Survivin were detected by reverse transcription-quantitative PCR and western blotting, respectively. Cell survival rate, proliferation, cell cycle and apoptosis were determined by Cell Counting Kit-8, cell double cytochemical staining and flow cytometry, respectively. It was found that using a combination of ultrasonic irradiation and the SonoVue microbubbles method increased the effectiveness of miR-378 transfection into hepatocellular carcinoma (HCC) cells, and increased the inhibition of cell survival and proliferation. Moreover, miR-378 increased the rate of apoptosis and upregulated the expression of Bax and p53, and suppressed the cell cycle and downregulated the expression of Cyclin D1, Bcl-2, Akt, β-catenin and Survivin much more effectively in the HCC cell line by applying the combined method. Thus, miR-378 was shown to be a suppressive factor to reduce proliferation and increase apoptosis in HCC cells. Additionally, the combination of ultrasonic irradiation and SonoVue microbubbles method was more efficient in the transfection of miRNA.

Nanoparticles for mucosal vaccine delivery

Mucosal surfaces represent important routes of entry into the human body for the majority of pathogens, and they constitute unique sites for targeted vaccine delivery. Nanoparticle-based drug delivery systems are emerging technologies for delivering and improving the efficacy of mucosal vaccines. Recent studies have provided new insights into formulation and delivery aspects of importance for the design of safe and efficacious mucosal subunit vaccines based on nanoparticles. These include novel nanomaterials, their physicochemical properties and formulation approaches, nanoparticle interaction with immune cells in the mucosa, and mucosal immunization and delivery strategies. Here, we present recent progress in the application of nanoparticle-based approaches for mucosal vaccine delivery and discuss future research challenges and opportunities in the field.

Advances in low-frequency ultrasound combined with microbubbles in targeted tumor therapy

The development of low-frequency ultrasound imaging technology and the improvement of ultrasound contrast agent production technology mean that they play an increasingly important role in tumor therapy. The interaction between ultrasound and microbubbles and their biological effects can transfer and release microbubbles carrying genes and drugs to target tissues, mediate the apoptosis of tumor cells, and block the embolization of tumor microvasculature. With the optimization of ultrasound parameters, the development of targeted microbubbles, and the emergence of various composite probes with both diagnostic and therapeutic functions, low-frequency ultrasound combined with microbubble contrast agents will bring new hope for clinical tumor treatment.

Minireview: Biophysical Mechanisms of Cell Membrane Sonopermeabilization. Knowns and Unknowns

Microbubble-assisted ultrasound has emerged as a promising method for the delivery of low-molecular-weight chemotherapeutic molecules, nucleic acids, therapeutic peptides, and antibodies in vitro and in vivo. Its clinical applications are under investigation for local delivery drug in oncology and neurology. However, the biophysical mechanisms supporting the acoustically mediated membrane permeabilization are not fully established. This review describes the present state of the investigations concerning the acoustically mediated stimuli (i.e., mechanical, chemical, and thermal stimuli) as well as the molecular and cellular actors (i.e., membrane pores and endocytosis) involved in the reversible membrane permeabilization process. The different hypotheses, which were proposed to give a biophysical description of the membrane permeabilization, are critically discussed.