Plasmid DNA-based gene transfer with ultrasound and microbubbles

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.

Strategies for High-Efficiency Mutation Using the CRISPR/Cas System

Clustered regularly interspaced short palindromic repeats (CRISPR)-associated systems have revolutionized traditional gene-editing tools and are a significant tool for ameliorating gene defects. Characterized by high target specificity, extraordinary efficiency, and cost-effectiveness, CRISPR/Cas systems have displayed tremendous potential for genetic manipulation in almost any organism and cell type. Despite their numerous advantages, however, CRISPR/Cas systems have some inherent limitations, such as off-target effects, unsatisfactory efficiency of delivery, and unwanted adverse effects, thereby resulting in a desire to explore approaches to address these issues. Strategies for improving the efficiency of CRISPR/Cas-induced mutations, such as reducing off-target effects, improving the design and modification of sgRNA, optimizing the editing time and the temperature, choice of delivery system, and enrichment of sgRNA, are comprehensively described in this review. Additionally, several newly emerging approaches, including the use of Cas variants, anti-CRISPR proteins, and mutant enrichment, are discussed in detail. Furthermore, the authors provide a deep analysis of the current challenges in the utilization of CRISPR/Cas systems and the future applications of CRISPR/Cas systems in various scenarios. This review not only serves as a reference for improving the maturity of CRISPR/Cas systems but also supplies practical guidance for expanding the applicability of this technology.

UTMD-mediated delivery of miR-21-5p inhibitor suppresses the development of lung cancer

BACKGROUND

Ultrasound-targeted microbubble destruction (UTMD) is a new type of gene delivery technology. MiR-21-5p was highly expressed in a variety of cancers. In this paper, miR-21-5p inhibitor was transfected into lung cancer cells by UTMD to observe its role in lung cancer.

METHODS

StarBase was used to analyze the miR-21-5p expression in lung cancer patients and its relationship with the prognosis of the patients. MiR-21-5p expression in lung cancer tissues or cell lines was determined by quantitative reverse transcription polymerase chain reaction (qRT-PCR). Effects of gradient concentration (0, 5, 10, 20, 30%) of SonoVue or gradient mechanical index (MI) (0, 0.5, 1, 1.5, 2 W/cm²) on the cell viability were detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). The targeting relationship between miR-21-5p and B-cell translocation gene 2 (BTG2) was predicted by TargetScan and confirmed by dual-luciferase reporter assay, while the expressions of the two genes were determined by qRT-PCR. Through liposome transfection or UTMD transfection, the effects of miR-21-5p/BTG2 on the biological behaviors of lung cancer cells, the size of xenograft tumors and the expressions of ki67 and miR-21-5p were measured by qRT-PCR, western blot, cell function experiments and immunohistochemistry, respectively.

RESULTS

MiR-21-5p expression was upregulated in lung cancer, which was associated with a poor prognosis. The optimal ultrasound conditions were 10% SonoVue concentration and 1 W/cm². UTMD transfection exerted a stronger effect than liposome transfection. MiR-21-5p promoted cell viability, proliferation and migration yet suppressed apoptosis by targeting BTG2. MiR-21-5p inhibitor reduced the size and volume of xenograft tumor and the expressions of ki67 and miR-21-5p in xenograft tumor tissues.

CONCLUSION

UTMD-mediated miR-21-5p inhibitor can more effectively suppress the development of lung cancer.

miR‑124‑3p regulates angiogenesis in peripheral arterial disease by targeting STAT3

Peripheral arterial disease (PAD) is the third leading cause of cardiovascular morbidity worldwide, after coronary artery disease and stroke. As endogenous regulators of gene expression, microRNAs (miRs) are implicated in the development and progression of various diseases, including types of cancer, autoimmune diseases and heart diseases. In the present study, the role of miR-124-3p in PAD was investigated. The reverse transcription-quantitative PCR results indicated that the expression levels of miR-124-3p were significantly increased in the ischemic tissue of the hindlimb ischemia (HLI) model and in hypoxic human umbilical vein endothelial cells compared with the corresponding control groups. Proliferation, wound healing and tube formation assays demonstrated the inhibition of miR-124-3p on angiogenesis in vitro and the HLI model indicated the same function of miR-124-3p in vivo. A dual-luciferase reporter revealed STAT3 as the target of miR-124-3p. The expression levels of miR-124-3p in human blood were negatively correlated with ankle-brachial index, which is an index for the evaluation of the severity of PAD. Collectively, the present study indicated that miR-124-3p was a critical regulator of angiogenesis in PAD, and a potential diagnostic, prognostic and therapeutic target for PAD.

[Application of ultrasound-enhanced gene and drug delivery to the ocular tissue]

Visual images provide an immensely rich source of information about the external world. Eye has characteristic structure sensory cells are arranged along the eye wall, and is filled inside with vitreous body. In recent years, intravitreal injection of anti-vascular endothelial growth factor (VEGF) agent had widely spread, and numerous number of patients who suffered ocular angiogenic disease such as diabetic retinopathy, age-related macular degeneration and retinal vascular occlusion for the disease, were treated and spared the blindness. Vitreous cavity was regarded as reservoir of drug, intravitreal injection is thought a sort of drug delivery. However, with regard to the administration of a selective drug deliver, it has not yet been solved. Our aim is to establish a new method of gene transfer, drug delivery using low-energy ultrasound to the eye, to date, we confirmed drug and gene deliver to the ocular tissue such as cornea, conjunctiva and retina with high efficiency. In addition, tissue damage was minimal. We have also shown that ultrasound irradiation with combination of a microbubbles or bubble liposome could be introduced drug and gene more effectively. Based on these knowledge, we will focus on development of a new device for intraocular ultrasound exposure and potential for therapeutic application of ultrasound to humans retinal disease such as retinal artery obstruction.

Improving ultrasound gene transfection efficiency by controlling ultrasound excitation of microbubbles

Ultrasound application in the presence of microbubbles has shown great potential for non-viral gene transfection via transient disruption of cell membrane (sonoporation). However, improvement of its efficiency has largely relied on empirical approaches without consistent and translatable results. The goal of this study is to develop a rational strategy based on new results obtained using novel experimental techniques and analysis to improve sonoporation gene transfection. In this study, we conducted experiments using targeted microbubbles that were attached to cell membrane to facilitate sonoporation. We quantified the dynamic activities of microbubbles exposed to pulsed ultrasound and the resulting sonoporation outcome, and identified distinct regimes of characteristic microbubble behaviors: stable cavitation, coalescence and translation, and inertial cavitation. We found that inertial cavitation generated the highest rate of membrane poration. By establishing direct correlation of ultrasound-induced bubble activities with intracellular uptake and pore size, we designed a ramped pulse exposure scheme for optimizing microbubble excitation to improve sonoporation gene transfection. We implemented a novel sonoporation gene transfection system using an aqueous two phase system (ATPS) for efficient use of reagents and high throughput operation. Using plasmids coding for the green fluorescence protein (GFP), we achieved a sonoporation transfection efficiency in rate aortic smooth muscle cells (RASMCs) of 6.9%±2.2% (n=9), comparable with lipofection (7.5%±0.8%, n=9). Our results reveal characteristic microbubble behaviors responsible for sonoporation and demonstrated a rational strategy to improve sonoporation gene transfection.