Influence of DNA-Microbubble Coupling on Contrast Ultrasound-Mediated Gene Transfection in Muscle and Liver

Microbubble–Nanoparticle Complexes for Ultrasound-Enhanced Cargo Delivery

Targeted delivery of therapeutics to specific tissues is critically important for reducing systemic toxicity and optimizing therapeutic efficacy, especially in the case of cytotoxic drugs. Many strategies currently exist for targeting systemically administered drugs, and ultrasound-controlled targeting is a rapidly advancing strategy for externally-stimulated drug delivery. In this non-invasive method, ultrasound waves penetrate through tissue and stimulate gas-filled microbubbles, resulting in bubble rupture and biophysical effects that power delivery of attached cargo to surrounding cells. Drug delivery capabilities from ultrasound-sensitive microbubbles are greatly expanded when nanocarrier particles are attached to the bubble surface, and cargo loading is determined by the physicochemical properties of the nanoparticles. This review serves to highlight and discuss current microbubble–nanoparticle complex component materials and designs for ultrasound-mediated drug delivery. Nanocarriers that have been complexed with microbubbles for drug delivery include lipid-based, polymeric, lipid–polymer hybrid, protein, and inorganic nanoparticles. Several schemes exist for linking nanoparticles to microbubbles for efficient nanoparticle delivery, including biotin–avidin bridging, electrostatic bonding, and covalent linkages. When compared to unstimulated delivery, ultrasound-mediated cargo delivery enables enhanced cell uptake and accumulation of cargo in target organs and can result in improved therapeutic outcomes. These ultrasound-responsive delivery complexes can also be designed to facilitate other methods of targeting, including bioactive targeting ligands and responsivity to light or magnetic fields, and multi-level targeting can enhance therapeutic efficacy. Microbubble–nanoparticle complexes present a versatile platform for controlled drug delivery via ultrasound, allowing for enhanced tissue penetration and minimally invasive therapy. Future perspectives for application of this platform are also discussed in this review.

Ultrasound-Targeted Microbubble Destruction: Modulation in the Tumor Microenvironment and Application in Tumor Immunotherapy

Tumor immunotherapy has shown strong therapeutic potential for stimulating or reconstructing the immune system to control and kill tumor cells. It is a promising and effective anti-cancer treatment besides surgery, radiotherapy and chemotherapy. Presently, some immunotherapy methods have been approved for clinical application, and numerous others have demonstrated promising in vitro results and have entered clinical trial stages. Although immunotherapy has exhibited encouraging results in various cancer types, however, a large proportion of patients are limited from these benefits due to specific characteristics of the tumor microenvironment such as hypoxia, tumor vascular malformation and immune escape, and current limitations of immunotherapy such as off-target toxicity, insufficient drug penetration and accumulation and immune cell dysfunction. Ultrasound-target microbubble destruction (UTMD) treatment can help reduce immunotherapy-related adverse events. Using the ultrasonic cavitation effect of microstreaming, microjets and free radicals, UTMD can cause a series of changes in vascular endothelial cells, such as enhancing endothelial cells’ permeability, increasing intracellular calcium levels, regulating gene expression, and stimulating nitric oxide synthase activities. These effects have been shown to promote drug penetration, enhance blood perfusion, increase drug delivery and induce tumor cell death. UTMD, in combination with immunotherapy, has been used to treat melanoma, non-small cell lung cancer, bladder cancer, and ovarian cancer. In this review, we summarized the effects of UTMD on tumor angiogenesis and immune microenvironment, and discussed the application and progress of UTMD in tumor immunotherapy.

Microbubble Enhanced Echocardiography in Current Cardiology Practice

Contrast-enhanced ultrasound imaging is a radiation-free clinical diagnostic tool that uses biocompatible contrast agents to enhance ultrasound signal, in order to improve image clarity and diagnostic performance. Ultrasound enhancing agents (UEA), which are usually gas microbubbles, are administered intravenously either by bolus injection or continuous infusion. UEA increase the accuracy and reliability of echocardiography, leading to changes in treatment, improving patient outcomes and lowering overall health care costs. In this review we describe: (1) the current clinical applications of ultrasound enhancing agents in echocardiography, with a brief review of the evidence underlying each of these applications; (2) emerging diagnostic and therapeutic applications of microbubble enhanced echocardiography (MEE), which rely either on the specific properties and composition of ultrasound enhancing agents or on the technical advances of clinical ultrasound systems; and (3) safety of MEE.

Ultrasound microbubble-mediated miR-503-5p downregulation suppressed in vitro CRC progression via promoting SALL1 expression

BACKGROUND

This study compared the effect of ultrasound microbubble-mediated miR-503-5p downregulation with that of pure liposome-mediated miR-503-5p downregulation on colorectal cancer (CRC) progression and explored the downstream mechanism.

METHODS

Bioinformatics tools were utilized to predict miR-503-5p-targeted genes and CRC progression-associated genes. MiR-503-5p and sal-like 1 (SALL1) expressions in CRC cells and tissues were analyzed by qRT-PCR and/or bioinformatics tools; their correlations with overall survival and clinicopathological features of CRC patients were presented, and their interaction was validated by dual-luciferase reporter assay. CRC cells received ultrasound microbubble-mediated miR-503-5p downregulation and/or liposome-mediated miR-503-5p downregulation or SALL1 silencing. Cell phenotype changes were evaluated by flow cytometry, as well as MTT, Wound healing, Transwell and tube formation assays. E-cadherin, N-cadherin, Vimentin, B-cell lymphoma (Bcl)- 2, Cleaved caspase-3, and SALL1 expressions in cells were analyzed by Western blot.

RESULTS

Upregulated miR-503-5p in CRC tissues and cells was detected, associated with poorer cell differentiation, easier lymph node metastasis and higher TNM stages, and related to poorer prognoses of CRC patients. Ultrasound microbubble-mediated miR-503-5p downregulation relative to pure liposome-mediated miR-503-5p downregulation better decreased viability, inhibited migration, invasion and tube formation, enhanced apoptosis, upregulated SALL1, E-cadherin and Cleaved caspase-3, and downregulated miR-503-5p, N-cadherin, Vimentin and Bcl-2 in CRC cells. SALL1 was targeted by miR-503-5p, low-expressed in CRC tissues and cells and positively related to CRC patients' survival. Silencing SALL1 exerted the opposite effects, which reversed the effects of ultrasound microbubble-mediated miR-503-5p downregulation and vice versa.

CONCLUSION

Ultrasound microbubble-mediated miR-503-5p downregulation suppressed in vitro CRC progression via promoting SALL1 expression.

Placental sFlt-1 Gene Delivery in Early Primate Pregnancy Suppresses Uterine Spiral Artery Remodeling

Uterine spiral artery remodeling (SAR) is essential for promoting placental perfusion and fetal development. A defect in SAR results in placental ischemia and increase in placental expression and serum levels of the soluble fms-like tyrosine kinase-1 (sFlt-1) receptor that binds to and suppresses vascular endothelial growth factor (VEGF) bioavailability, thereby leading to maternal vascular dysfunction. We have established a nonhuman primate model of impaired SAR and maternal vascular dysfunction by prematurely elevating estradiol levels in early baboon pregnancy. However, it is unknown whether this primate model of defective SAR involves an increase in placental expression of sFlt-1, which may suppress VEGF bioavailability and thus SAR in the first trimester. Therefore, to establish the role of sFlt-1 in early pregnancy, SAR was quantified in baboons treated on days 25 through 59 of gestation (term = 184 days) with estradiol or with the sFlt-1 gene targeted selectively to the placental basal plate by ultrasound-mediated/microbubble-facilitated gene delivery technology. Placental basal plate sFlt-1 protein expression was 2-fold higher (P < 0.038) and the level of SAR for vessels > 25 µm in diameter was 72% and 63% lower (P < 0.01), respectively, in estradiol-treated and sFlt-1 gene-treated baboons than in untreated animals. In summary, prematurely elevating estradiol levels or sFlt-1 gene delivery increased placental basal plate sFlt-1 protein expression and suppressed SAR in early baboon pregnancy. This study makes the novel discovery that in elevated levels sFlt-1 has a role both in suppressing SAR in early primate pregnancy and maternal vascular endothelial function in late gestation.

Ultrasound microbubbles-mediated miR-216b affects MALAT1-miRNA axis in non-small cell lung cancer cells

MiR-216b is ectopically expressed in various cancers. Ultrasound microbubbles (UTMBs) are an effective method for miRNA delivery. This article mainly explored the involvement of lncRNA in the effects of UTMBs-mediated miR-216b on non-small cell lung cancer (NSCLC) progression. Expressions and relationship of miR-216b and MALAT1 were examined using quantitative real-time polymerase chain reaction (qRT-PCR), Pearson, TargetScan, and dual-luciferase reporter assay. After the transfection with liposome- or UTMBs-mediated miR-216b mimic (M) or MALAT1 overexpression plasmid alone or together, levels of miR-216b and MALAT1, cell biological behaviors, as well as expressions of apoptosis- and epithelial mesenchymal transition (EMT)-related markers were examined using qRT-PCR, cell functional experiments, and western blot. Besides, we used qRT-PCR to quantify the expressions of multiple downstream miRNAs of MALAT1. MiR-216b expression was weakened yet MALAT1 expression was enhanced in NSCLC tissues, and miR-216b was negatively bound to MALAT1. TargetScan analysis manifested that miR-216b, targeted by MALAT1, was down-regulated in NSCLC cells. UTMBs-mediated miR-216b M further intensified miR-216b level yet weakened cell biological behaviors. The inhibitory effect of UTMBs-mediated miR-216b M on cell biological behaviors and MALAT1 expression was greatly better relative to that of miR-216b M. Moreover, miR-216b restrained the cell biological behaviors by repressing MALAT1 expression. We further manifested that miR-216b facilitated the expressions of apoptosis-related markers, but restrained those of EMT-related markers by repressing MALAT1 expression. Moreover, UTMBs-mediated miR-216b M enhanced the expressions of downstream multiple miRNAs of MALAT1, but this tendency was reversed by co-transfection of overexpressed MALAT1 and miR-216b M. Collectively, UTMBs-mediated miR-216b M restrained NSCLC cell growth by modulating the MALAT1-miRNA axis.

Synergies between therapeutic ultrasound, gene therapy and immunotherapy in cancer treatment

Due to the ease of use and excellent safety profile, ultrasound is a promising technique for both diagnosis and site-specific therapy. Ultrasound-based techniques have been developed to enhance the pharmacokinetics and efficacy of therapeutic agents in cancer treatment. In particular, transfection with exogenous nucleic acids has the potential to stimulate an immune response in the tumor microenvironment. Ultrasound-mediated gene transfection is a growing field, and recent work has incorporated this technique into cancer immunotherapy. Compared with other gene transfection methods, ultrasound-mediated gene transfection has a unique opportunity to augment the intracellular uptake of nucleic acids while safely and stably modulating the expression of immunostimulatory cytokines. The development and commercialization of therapeutic ultrasound systems further enhance the potential translation. In this Review, we introduce the underlying mechanisms and ongoing preclinical studies of ultrasound-based techniques in gene transfection for cancer immunotherapy. Furthermore, we expand on aspects of therapeutic ultrasound that impact gene therapy and immunotherapy, including tumor debulking, enhancing cytokines and chemokines and altering nanoparticle pharmacokinetics as these effects of ultrasound cannot be fully dissected from targeted gene therapy. We finally explore the outlook for this rapidly developing field.

Novel Technologies for Target Delivery of Therapeutics to the Placenta during Pregnancy: A Review

Uterine spiral artery remodeling is essential for placental perfusion and fetal growth and, when impaired, results in placental ischemia and pregnancy complications, e.g., fetal growth restriction, preeclampsia, premature birth. Despite the high incidence of adverse pregnancies, current treatment options are limited. Accordingly, research has shifted to the development of gene therapy technologies that provide targeted delivery of "payloads" to the placenta while limiting maternal and fetal exposure. This review describes the current strategies, including placental targeting peptide-bound liposomes, nanoparticle or adenovirus constructs decorated with specific peptide sequences and placental gene promoters delivered via maternal IV injection, directly into the placenta or the uterine artery, as well as noninvasive site-selective targeting of regulating genes conjugated with microbubbles via contrast-enhanced ultrasound. The review also provides a perspective on the effectiveness of these technologies in various animal models and their practicability and potential use for targeted placental delivery of therapeutics and genes in adverse human pregnancies affected by placental dysfunction.

UTMD promoted local delivery of miR-34a-mimic for ovarian cancer therapy

MicroRNA-mediated gene therapy is emerging as a promising method for the treatment of ovarian cancer, but the development of miRNA mimic delivery vectors is still in its infancy, where the safety and efficacy of miR-34a-mimic remain unknown. Ultrasound-targeted microbubble destruction (UTMD) can be an effective and minimally invasive tool for the delivery of miR-34a-mimic in vitro and in vivo. Here, we describe a high-efficiency gene delivery strategy by using miR-34a-mimic loaded folate modified microbubbles (miR-34a-FM) with a portable ultrasonic irradiation system. Ultrasonic parameters, including acoustic intensity (AI), exposure time (ET) and duty cycle (DC), were optimized and the optimal acoustic condition (1.0 W/cm², 20 s, and 15% DC) was used to deliver miRNA-34a into cells in vitro. MiR-34a mimic was successfully introduced into the cytoplasm and was found to inhibit proliferation and induce apoptosis of SK-OV-3 cells. Next, miR-34a-mimic was delivered to tumor tissue via UTMD, inhibiting tumor growth and prolonging the survival time of mice. In summary, UTMD-mediated miR-34a-mimic delivery has potential application in the clinical treatment of ovarian cancer.

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

Acute respiratory distress syndrome (ARDS) is characterized by increased permeability of the alveolar–capillary membrane, a thin barrier composed of adjacent monolayers of alveolar epithelial and lung microvascular endothelial cells. This results in pulmonary edema and severe hypoxemia and is a common cause of death after both viral (e.g., SARS-CoV-2) and bacterial pneumonia. The involvement of the lung in ARDS is notoriously heterogeneous, with consolidated and edematous lung abutting aerated, less injured regions. This makes treatment difficult, as most therapeutic approaches preferentially affect the normal lung regions or are distributed indiscriminately to other organs. In this review, we describe the use of thoracic ultrasound and microbubbles (USMB) to deliver therapeutic cargo (drugs, genes) preferentially to severely injured areas of the lung and in particular to the lung endothelium. While USMB has been explored in other organs, it has been under-appreciated in the treatment of lung injury since ultrasound energy is scattered by air. However, this limitation can be harnessed to direct therapy specifically to severely injured lungs. We explore the cellular mechanisms governing USMB and describe various permutations of cargo administration. Lastly, we discuss both the challenges and potential opportunities presented by USMB in the lung as a tool for both therapy and research.

Ultrasonic irradiation and SonoVue microbubbles-mediated RNA interference targeting PRR11 inhibits breast cancer cells proliferation and metastasis, but promotes apoptosis

The present study compared the effects of ultrasonic irradiation and SonoVue microbubbles (US) or Lipofectamine 3000 on the transfection of small interfering RNA for PRR11 (siPRR11) and Proline-rich protein 11 (PRR11) overexpression plasmid into breast cancer cells. SiPRR11 and PRR11 overexpression plasmid were transfected into breast cancer MCF7 cells mediated by US and Lipofectamine 3000. PRR11 expressions in breast cancer and normal tissues were determined using Gene Expression Profiling Interactive Analysis (GEPIA). The viability, proliferation, migration, invasion and apoptosis of breast cancer cells were respectively measured by MTT assay, clone formation assay, scratch wound-healing assay, Transwell assay and flow cytometry. PRR11 and epithelial-to-mesenchymal transition (EMT)-related and apoptosis-related (B-cell lymphoma 2, Bcl-2; Bcl-2-associated protein X, Bax) proteins’ expressions were detected by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot as appropriate. As ultrasonic intensity increased, the viability of MCF7 cells was decreased. Results from GEPIA suggested that PRR11 was up-regulated in breast cancer. Silencing PRR11 mediated by US showed a higher efficiency than by Lipofectamine 3000. SiPRR11 transfected by Lipofectamine 3000 suppressed cells growth and metastasis, while promoted cell apoptosis. Moreover, E-cadherin (E-cad) and Bax expressions were high but N-cadherin (N-cad), Snail and Bcl-2 expressions were low. However, overexpressed PRR11 caused the opposite effects. More importantly, transfection of siPRR11 and PRR11 overexpression plasmid using US had a higher efficacy than using Lipofectamine 3000. US transfection of PRR11 siRNA showed better effects on inhibiting breast cancer progression. The current findings contribute to a novel treatment for breast cancer.

The better effects of microbubble ultrasound transfection of miR-940 on cell proliferation inhibition and apoptosis promotion in human cervical cancer cells

Purpose

Cervical cancer is the second leading cause of women’s cancer-related death. MiR-940 has been reported as a critical factor in various cancers. Based on the high transfection efficiency and low side effect, the clinical application of microbubble ultrasound contrast agent in gene treatment has attracted a widespread attention. In this study, we determined the mechanism of miR-940 inhibiting cell proliferation and cycle procession, and promoting cell apoptosis in cervical cancer Hela cells. In addition, we compared the effects of different transfection methods, including liposome, microbubble, ultrasound, and microbubble coupled with ultrasound.

Patients and methods

MTT assay, PI staining, and Annexin-Ⅴ/PI staining assays were, respectively, performed to evaluate cell proliferation status, cell cycle progression, and apoptosis status. RT-PCR and Western blot were conducted to measure the levels of cell cycle- and apoptosis-related factors, and the phosphorylation levels of PI3K and Akt.

Results

Results showed that the overexpression of miR-940 inhibited cell proliferation, blocked cell cycle, and promoted apoptosis by regulating cell cycle-related factors (such as inhibited Cyclin D1 and CDK4) and apoptosis-related factors (such as promoted Puma and Bax, inhibited Bcl-2 and Cleaved caspase9), and inhibiting the phosphorylation and activation of PI3K/AKT pathway. Among all of them, miR-940 transfected with microbubble and ultrasound showed the greatest changes.

Conclusion

It provides evidence that miR-940 could be a wonderful biomarker and treatment agent for cervical cancer, and microbubble ultrasound would have more wide application in the clinical treatment of cancers.

Vascular Endothelial Growth Factor Delivery to Placental Basal Plate Promotes Uterine Artery Remodeling in the Primate

Extravillous trophoblast (EVT) uterine artery remodeling (UAR) promotes placental blood flow, but UAR regulation is unproven. Elevating estradiol (E2) in early baboon pregnancy suppressed UAR and EVT vascular endothelial growth factor (VEGF) expression, but this did not prove that VEGF mediated this process. Therefore, our primate model of prematurely elevating E2 and contrast-enhanced ultrasound cavitation of microbubble (MB) carriers was used to deliver VEGF DNA to the placental basal plate (PBP) to establish the role of VEGF in UAR. Baboons were treated on days 25 to 59 of gestation (term, 184 days) with E2 alone or with E2 plus VEGF DNA-conjugated MBs briefly infused via a maternal peripheral vein on days 25, 35, 45, and 55. At each of these times an ultrasound beam was directed to the PBP to collapse the MBs and release VEGF DNA. VEGF DNA-labeled MBs per contrast agent was localized in the PBP but not the fetus. Remodeling of uterine arteries >25 µm in diameter on day 60 was 75% lower (P < 0.001) in E2-treated (7% ± 2%) than in untreated baboons (30% ± 4%) and was restored to normal by E2/VEGF. VEGF protein levels (signals/nuclear area) within the PBP were twofold lower (P < 0.01) in E2-treated (4.2 ± 0.9) than in untreated (9.8 ± 2.8) baboons and restored to normal by E2/VEGF (11.9 ± 1.6), substantiating VEGF transfection. Thus, VEGF gene delivery selectively to the PBP prevented the decrease in UAR elicited by prematurely elevating E2 levels, establishing the role of VEGF in regulating UAR in vivo during primate pregnancy.