Development of anionic bubble lipopolyplexes for efficient and safe gene transfection with ultrasound exposure in mice

RNAi-Mediated Knockdown of Cottontail Rabbit Papillomavirus Oncogenes Using Low-Toxicity Lipopolyplexes as a Paradigm to Treat Papillomavirus-Associated Cancers

The cottontail rabbit papillomavirus (CRPV)-associated VX2 carcinoma of the New Zealand White rabbit serves as a model system for human papillomavirus (HPV)-associated head and neck squamous cell carcinomas (HNSCCs). The aim of this study was to evaluate the tumor-inhibiting effect of RNAi-mediated knockdown of the CRPV oncogenes, E6 and E7, using siRNA-loaded lipopolyplexes (LPPs). VX2-carcinoma-derived cells were cultured for up to 150 passages. In addition, CRPV E6 and E7 oncogenes were transiently expressed in COS-7 cells. Efficiency and safety of LPPs were evaluated in both VX2 cells and the COS-7 cell line. Both of these in vitro CRPV systems were validated and characterized by fluorescence microscopy, Western blot, and RT-qPCR. Efficient knockdown of CRPV E6 and E7 was achieved in VX2 cells and COS-7 cells pretransfected with CRPV E6 and E7 expression vectors. Knockdown of CRPV oncogenes in VX2 cells resulted in reduced viability, migration, and proliferation and led to a G0/G1 block in the cell cycle. CRPV E6 and E7 siRNA-loaded LPPs could represent promising therapeutic agents serving as a paradigm for the treatment of papillomavirus-positive cancers and could be of value for the treatment of CRPV-associated diseases in the rabbit such as papillomas and cancers of the skin.

脳を標的とした薬物・遺伝子デリバリーシステムの開発とその評価

New drug modalities such as nucleic acid, gene, cells, and nanoparticles are expected for treating refractory diseases. However, these drugs have larger size and low cell membrane permeability; therefore, drug delivery systems (DDS) are essential for delivery to the intended site at the organ and cellular level. In case of the brain, drug migration to the brain from blood circulation is extremely limited by the blood-brain barrier (BBB). Therefore, brain-targeted DDS technologies with the ability to overcome the BBB are being intensively developed. Ultrasound-mediated BBB opening can transiently permeabilize the BBB via cavitation and oscillation and is expected to transfer drugs into the brain. Besides several fundamental studies, clinical studies on BBB opening have also been undertaken, proving its efficacy and safety. Our group has developed an ultrasound-mediated DDS to the brain for low-molecular weight drugs as well as plasmid DNA and mRNA intended for gene therapy. We also evaluated the distribution of gene expression to obtain essential information for applying gene therapy. Here, I provide general information on DDS to the brain, and describe our research progress in brain-targeted delivery of plasmid DNA and mRNA using BBB opening.

A Review of Different Types of Liposomes and Their Advancements as a Form of Gene Therapy Treatment for Breast Cancer

Breast cancer incidence and mortality rates have increased exponentially during the last decade, particularly among female patients. Current therapies, including surgery and chemotherapy, have significant negative physical and mental impacts on patients. As a safer alternative, gene therapy utilising a therapeutic gene with the potential to treat various ailments is being considered. Delivery of the gene generally utilises viral vectors. However, immunological reactions and even mortality have been recorded as side effects. As a result, non-viral vectors, such as liposomes, a system composed of lipid bilayers formed into nanoparticles, are being studied. Liposomes have demonstrated tremendous potential due to their limitless ability to combine many functions into a system with desirable characteristics and functionality. This article discusses cationic, anionic, and neutral liposomes with their stability, cytotoxicity, transfection ability, cellular uptake, and limitation as a gene carrier suitable for gene therapy specifically for cancer. Due to the more practical approach of employing electrostatic contact with the negatively charged nucleic acid and the cell membrane for absorption purposes, cationic liposomes appear to be more suited for formulation for gene delivery and therapy for breast cancer treatment. As the other alternatives have numerous complicated additional modifications, attachments need to be made to achieve a functional gene therapy system for breast cancer treatment, which were also discussed in this review. This review aimed to increase understanding and build a viable breast cancer gene therapy treatment strategy.

VCAM-1 Targeted Lipopolyplexes as Vehicles for Efficient Delivery of shRNA-Runx2 to Osteoblast-Differentiated Valvular Interstitial Cells; Implications in Calcific Valve Disease Treatment

Calcific aortic valve disease (CAVD) is a progressive inflammatory disorder characterized by extracellular matrix remodeling and valvular interstitial cells (VIC) osteodifferentiation leading to valve leaflets calcification and impairment movement. Runx2, the master transcription factor involved in VIC osteodifferentiation, modulates the expression of other osteogenic molecules. Previously, we have demonstrated that the osteoblastic phenotypic shift of cultured VIC is impeded by Runx2 silencing using fullerene (C60)-polyethyleneimine (PEI)/short hairpin (sh)RNA-Runx2 (shRunx2) polyplexes. Since the use of polyplexes for in vivo delivery is limited by their instability in the plasma and the non-specific tissue interactions, we designed and obtained targeted, lipid-enveloped polyplexes (lipopolyplexes) suitable for (1) systemic administration and (2) targeted delivery of shRunx2 to osteoblast-differentiated VIC (oVIC). Vascular cell adhesion molecule (VCAM)-1 expressed on the surface of oVIC was used as a target, and a peptide with high affinity for VCAM-1 was coupled to the surface of lipopolyplexes encapsulating C60-PEI/shRunx2 (V-LPP/shRunx2). We report here that V-LPP/shRunx2 lipopolyplexes are cyto- and hemo-compatible and specifically taken up by oVIC. These lipopolyplexes are functional as they downregulate the Runx2 gene and protein expression, and their uptake leads to a significant decrease in the expression of osteogenic molecules (OSP, BSP, BMP-2). These results identify V-LPP/shRunx2 as a new, appropriately directed vehicle that could be instrumental in developing novel strategies for blocking the progression of CAVD using a targeted nanomedicine approach.

Stimuli-responsive nanomaterials for cancer treatment: boundaries, opportunities and applications

Small molecule drugs, including most chemotherapies, are rapidly degraded and/or eliminated from the body, which is why high doses of these drugs are necessary, potentially producing toxic effects. Several types of nanoparticles loaded with anti-cancer drugs have been designed to overcome the disadvantages of conventional therapies. Modified nanoparticles can circulate for a long time, thus improving the solubility and biodistribution of drugs. Furthermore, they also allow the controlled release of the payload once its target tissue has been reached. These mechanisms can reduce the exposure of healthy tissues to chemotherapeutics, since the drugs are only released in the presence of specific tumour stimuli. Overall, these properties can improve the effectiveness of treatments while reducing undesirable side effects. In this article, we review the recent advances in stimuli-responsive albumin, gold and magnetic nanostructures for controlled anti-cancer drug delivery. These nanostructures were designed to release drugs in response to different internal and external stimuli of the cellular environment, including pH, redox, light and magnetic fields. We also describe various examples of applications of these nanomaterials. Overall, we shed light on the properties, potential clinical translation and limitations of stimuli-responsive nanoparticles for cancer treatment.

Lipodendriplexes mediated enhanced gene delivery: a cellular to pre-clinical investigation

Clinical success of effective gene therapy is mainly hampered by the insufficiency of safe and efficient internalization of a transgene to the targeted cellular site. Therefore, the development of a safe and efficient nanocarrier system is one of the fundamental challenges to transfer the therapeutic genes to the diseased cells. Polyamidoamine (PAMAM) dendrimer has been used as an efficient non-viral gene vector (dendriplexes) but the toxicity and unusual biodistribution induced by the terminal amino groups (–NH₂) limit its in vivo applications. Hence, a state of the art lipid modification with PAMAM based gene carrier (lipodendriplexes) was planned to investigate theirs in vitro (2D and 3D cell culture) and in vivo behaviour. In vitro pDNA transfection, lactate dehydrogenase (LDH) release, reactive oxygen species (ROS) generation, cellular protein contents, live/dead staining and apoptosis were studied in 2D cell culture of HEK-293 cells while GFP transfection, 3D cell viability and live/dead staining of spheroids were performed in its 3D cell culture. Acute toxicity studies including organ to body index ratio, hematological parameters, serum biochemistry, histopathological profiles and in vivo transgene expression were assessed in female BALB/c mice. The results suggested that, in comparison to dendriplexes the lipodendriplexes exhibited significant improvement of pDNA transfection (p < 0.001) with lower LDH release (p < 0.01) and ROS generation (p < 0.05). A substantially higher cellular protein content (p < 0.01) and cell viability were also observed in 2D culture. A strong GFP expression with an improved cell viability profile (p < 0.05) was indicated in lipodendriplexes treated 3D spheroids. In vivo archives showed the superiority of lipid-modified nanocarrier system, depicted a significant increase in green fluorescent protein (GFP) expression in the lungs (p < 0.01), heart (p < 0.001), liver (p < 0.001) and kidneys (p < 0.001) with improved serum biochemistry and hematological profile as compared to unmodified dendriplexes. No tissue necrosis was evident in the animal groups treated with lipid-shielded molecules. Therefore, a non-covalent conjugation of lipids with PAMAM based carrier system could be considered as a promising approach for an efficient and biocompatible gene delivery system.

Ultrasound-responsive nanobubble-mediated gene transfection in the cerebroventricular region by intracerebroventricular administration in mice

AIM

Intracerebroventricular (ICV) administration of ultrasound-responsive bubbles and cranial ultrasound irradiation is reported as a transfection system for the cerebroventricular region. This study aimed to characterize the transfection system with respect to transfection efficiency, spatial distribution of transgene expression, and safety.

METHODS

Plasmid DNA was transfected to mouse brain by ICV injection of ultrasound-responsive nanobubbles, followed by ultrasound irradiation to brain. Spatial distribution of transgene expression in the cerebroventricular region was investigated using multicolor deep imaging.

RESULT

This transfection system efficiently transferred the transgene to the choroid plexus with no morphological change or cerebral hemorrhage. Moreover, sustained secretion of transgenic protein was achieved by transferring the transgene encoding the secretable protein.

CONCLUSION

We successfully developed an ultrasound-responsive nanobubbles-mediated method for gene transfection into the cerebroventricular region via ICV administration in mice.

Anti-ICAM-1 antibody-modified nanostructured lipid carriers: a pulmonary vascular endothelium-targeted device for acute lung injury therapy

BACKGROUND

Acute lung injury (ALI) is a life-threatening clinical syndrome without effective treatment. Targeting delivery of glucocorticoid to lung shows potential efficacy for ALI based on their anti-inflammatory and anti-fibrotic properties, breaking through their clinical application limitation due to systemic side effects. This work was aimed to establish lung-targeted dexamethasone (DEX) loaded nanostructured lipid carriers (NLCs) with opposite surface charge and investigate their therapeutic effects on lipopolysaccharide (LPS)-induced ALI mice.

RESULTS

The diameter of anionic anti-intercellular adhesion molecule 1 (anti-ICAM-1) antibody-conjugated DEX-loaded NLCs (ICAM/DEX/NLCs) and the cationic ones with octadecylamine (ODA) modification (ICAM/DEX/ODA-NLCs) was about 249.9 and 235.9 nm. The zeta potential of ICAM/DEX/NLCs and ICAM/DEX/ODA-NLCs was about - 30.3 and 37.4 mV, respectively. Relative to the non-targeted control and ICAM/DEX/ODA-NLCs, ICAM/DEX/NLCs exhibited higher in vitro cellular uptake in LPS-activated human vascular endothelial cell line EAhy926 after CAM-mediated endocytosis, and stronger in vivo pulmonary distribution in the ALI model mice. In vivo i.v. administration of ICAM/DEX/NLCs significantly attenuated pulmonary inflammatory cells infiltration, and the production of pro-inflammatory cytokine TNF-α and IL-6 in ALI mice. H&E stain also revealed positive histological improvements by ICAM/DEX/NLCs.

CONCLUSIONS

ICAM/DEX/NLCs may represent a potential pulmonary endothelium targeted device, which facilitate translation of DEX into clinical ALI treatment.

Serum Nuclease Susceptibility of mRNA Cargo in Condensed Polyplexes

Messenger RNA (mRNA) is a biomolecule with a wide range of promising clinical applications. However, the unstable nature of mRNA and its susceptibility to degradation by ribonucleases (RNases) necessitate the use of specialized formulations for delivery. Polycations are an emerging class of synthetic carriers capable of packaging nucleic acids, and may serve as suitable RNase-resistant formulations for mRNA administration. Here, we explore the application of VIPER and sunflower polycations, two polycations previously synthesized by our group, for the delivery of mRNA in comparison to branched poly(ethylenimine); all three polycations have been shown to efficiently deliver plasmid DNA (pDNA) to cultured cells. Despite successful mRNA condensation and packaging, transfection studies reveal that these three polycations can only efficiently deliver mRNA under serum-free conditions, while pDNA delivery is achieved even in the presence of serum. RNase resistance studies confirm that nuclease degradation of mRNA cargo remains a significant barrier to mRNA delivery using these polycations. These results emphasize the need for additional strategies for nuclease protection of mRNA cargo beyond electrostatic complexation with polycation.

Efficient gene transfection to the brain with ultrasound irradiation in mice using stabilized bubble lipopolyplexes prepared by the surface charge regulation method

Introduction

We previously developed anionic ternary bubble lipopolyplexes, an ultrasound-responsive carrier, expecting safe and efficient gene transfection. However, bubble lipopolyplexes have a low capacity for echo gas (C₃F₈) encapsulation (EGE) in nonionic solution such as 5% glucose. On the other hand, we were able to prepare bubble lipopolyplexes by inserting phosphate-buffered saline before C₃F₈ encapsulation. Surface charge regulation (SCR) by electrolytes stabilizes liposome/plasmid DNA (pDNA) complexes by accelerated membrane fusion. Considering these facts, we hypothesized that SCR by electrolytes such as NaCl would promote C₃F₈ encapsulation in bubble lipopolyplexes mediated by accelerated membrane fusion. We defined this hypothesis as SCR-based EGE (SCR-EGE). Bubble lipopolyplexes prepared by the SCR-EGE method (SCR-EGE bubble lipopolyplexes) are expected to facilitate the gene transfection because of the high amount of C₃F₈. Therefore, we applied these methods for gene delivery to the brain and evaluated the characteristics of transgene expression in the brain.

Methods

First, we measured the encapsulation efficiency of C₃F₈ in SCR-EGE bubble lipopolyplexes. Next, we applied these bubble lipopolyplexes to the mouse brain; then, we evaluated the transfection efficiency. Furthermore, three-dimensional transgene distribution was observed using multicolor deep imaging.

Results

SCR-EGE bubble lipopolyplexes had a higher C₃F₈ content than conventional bubble lipopolyplexes. In terms of safety, SCR-EGE bubble lipopolyplexes possessed an anionic potential and showed no aggregation with erythrocytes. After applying SCR-EGE bubble lipopolyplexes to the brain, high transgene expression was observed by combining with ultrasound irradiation. As a result, transgene expression mediated by SCR-EGE bubble lipopolyplexes was observed mainly on blood vessels and partially outside of blood vessels.

Conclusion

The SCR-EGE method may promote C₃F₈ encapsulation in bubble lipopolyplexes, and SCR-EGE bubble lipopolyplexes may be potent carriers for efficient and safe gene transfection in the brain, especially to the blood vessels.

Development of magnetic anionic liposome/atelocollagen complexes for efficient magnetic drug targeting

Magnetic nanoparticle-incorporated liposomes (magnetic liposomes) are considered a promising site-specific drug delivery carrier vehicle. With regard to their surface charge, magnetic anionic liposomes (Mag-AL) demonstrate little toxicity in comparison with magnetic cationic liposomes (Mag-CL), whereas their cellular association and uptake efficiency are low. In the current study, we constructed complexes of Mag-AL and atelocollagen (ATCOL), which is a biocompatible and minimally immunogenic biomaterial, to improve the cellular uptake properties of Mag-AL in vitro and in vivo. The cellular association and/or uptake of Mag-AL in RAW264 cells, a murine macrophage-like cell line, under a magnetic field was significantly increased when Mag-AL was complexed with ATCOL, and the highest cellular association was observed with complexes constructed using 5 µg/mL of ATCOL. The complexes showed liposome concentration-dependent and time-dependent cellular association under a magnetic field, and their cellular uptake efficiency was comparable with that of Mag-CL. In addition, Mag-CL showed significant cytotoxicity in a liposome concentration-dependent manner, whereas Mag-AL/ATCOL complexes produced no cytotoxic effect against RAW264 cells. Furthermore, the efficient cellular association of Mag-AL/ATCOL complexes in RAW264 cells was observed even in the presence of serum, and their liver accumulation was significantly increased at a magnetic field-exposed region after intravenous injection in rats. These results indicate that Mag-AL/ATCOL complexes could be a safe and efficient magnetic responsive drug carrier.

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

The use of ultrasound has gained great interest for nucleic acids delivery. Ultrasound can reach deep tissues in non-invasive manner. The process of sonoporation is based on the use of low-frequency ultrasound combined with gas-filled microbubbles (MBs) allowing an improved delivery of molecules including nucleic acids in the insonified tissue. For in vivo gene transfer, the engineering of cationic MBs is essential for creating strong electrostatic interactions between MBs and nucleic acids leading to their protection against nucleases degradation and high concentration within the target tissue. Cationic MBs must be stable enough to withstand nucleic acids interaction, have a good size distribution for in vivo administration, and enough acoustic activity to be detected by echography. This review aims to summarize the basic principles of ultrasound-based delivery and new knowledge acquired in these recent years about this method. A focus is made on gene delivery by discussing reported studies made with cationic MBs including ours. They have the ability for efficient delivery of plasmid DNA (pDNA), mRNA or siRNA. Last, we discuss about the key challenges that have to be faced for a fine use of this delivery system.

Recent Advances in Endogenous and Exogenous Stimuli-Responsive Nanocarriers for Drug Delivery and Therapeutics

Significant progress has been achieved in the development of stimuli-responsive nanocarriers for drug delivery, diagnosis, and therapy. Various types of triggers are utilized in the development of nanocarrier delivery. Endogenous factors such as changes in pH, redox, gradient, and enzyme concentration which are linked to disease progression have been utilized for controlling biodistribution and releasing drugs from nanocarriers, as well as increasing subsequent pharmacological activity at the disease site. Nanocarriers which respond to artificially-induced exogenous factors (such as temperature, light, magnetic field, and ultrasound) have also been developed. This review aims to discuss recent advances in the design of stimuli-responsive nanocarriers which appear to have a promising future in medicine.

Lipopolyplex for Therapeutic Gene Delivery and Its Application for the Treatment of Parkinson's Disease

Lipopolyplex is a core-shell structure composed of nucleic acid, polycation and lipid. As a non-viral gene delivery vector, lipopolyplex combining the advantages of polyplex and lipoplex has shown superior colloidal stability, reduced cytotoxicity, extremely high gene transfection efficiency. Following intravenous administration, there are many strategies based on lipopolyplex to overcome the complex biological barriers in systemic gene delivery including condensation of nucleic acids into nanoparticles, long circulation, cell targeting, endosomal escape, release to cytoplasm and entry into cell nucleus. Parkinson's disease (PD) is the second most common neurodegenerative disorder and severely influences the patients' life quality. Current gene therapy clinical trials for PD employing viral vectors didn't achieve satisfactory efficacy. However, lipopolyplex may become a promising alternative approach owing to its stability in blood, ability to cross the blood-brain barrier (BBB) and specific targeting to diseased brain cells.

Three-Dimensional Imaging of the Intracellular Fate of Plasmid DNA and Transgene Expression: ZsGreen1 and Tissue Clearing Method CUBIC Are an Optimal Combination for Multicolor Deep Imaging in Murine Tissues

Evaluation methods for determining the distribution of transgene expression in the body and the in vivo fate of viral and non-viral vectors are necessary for successful development of in vivo gene delivery systems. Here, we evaluated the spatial distribution of transgene expression using tissue clearing methods. After hydrodynamic injection of plasmid DNA into mice, whole tissues were subjected to tissue clearing. Tissue clearing followed by confocal laser scanning microscopy enabled evaluation of the three-dimensional distribution of transgene expression without preparation of tissue sections. Among the tested clearing methods (ClearT2, SeeDB, and CUBIC), CUBIC was the most suitable method for determining the spatial distribution of transgene expression in not only the liver but also other tissues such as the kidney and lung. In terms of the type of fluorescent protein, the observable depth for green fluorescent protein ZsGreen1 was slightly greater than that for red fluorescent protein tdTomato. We observed a depth of ~1.5 mm for the liver and 500 μm for other tissues without preparation of tissue sections. Furthermore, we succeeded in multicolor deep imaging of the intracellular fate of plasmid DNA in the murine liver. Thus, tissue clearing would be a powerful approach for determining the spatial distribution of plasmid DNA and transgene expression in various murine tissues.

Co-administration of Microbubbles and Drugs in Ultrasound-Assisted Drug Delivery: Comparison with Drug-Carrying Particles

There are two alternative approaches to ultrasound-assisted drug delivery. First, the drug can be entrapped into or attached onto the ultrasound-responsive particles and administered in the vasculature, to achieve ultrasound-triggered drug release from the particles and localized tissue deposition in response to ultrasound treatment of the target zone. Second, the drug can be co-administered with the microbubbles or other sonosensitive particles. In this case, the action of ultrasound on the particles (which act as cavitation nuclei) results in the transient improvement of permeability of the physiological barriers, so that the circulating drug can exit the bloodstream and get into the target tissues and cells. We discuss and compare both of these approaches, their characteristic advantages and disadvantages for the specific drug delivery scenarios. Clearly, the system based on the off-label use of the existing approved microbubbles and drugs (or drug carriers) will have a chance of getting to clinical trials faster and with lesser resources spent. However, if a superior curative potential of a sonosensitive drug carrier is proven, and formulation stability problems are addressed properly, this approach may find its way to practical use, especially for nucleic acid delivery scenarios.

Efficient Gene Delivery by Sonoporation Is Associated with Microbubble Entry into Cells and the Clathrin-Dependent Endocytosis Pathway

Microbubble oscillation at specific ultrasound settings leads to permeabilization of surrounding cells. This phenomenon, referred to as sonoporation, allows for the in vitro and in vivo delivery of extracellular molecules, including plasmid DNA. To date, the biological and physical mechanisms underlying this phenomenon are not fully understood. The aim of this study was to investigate the interactions between microbubbles and cells, as well as the intracellular routing of plasmid DNA and microbubbles, during and after sonoporation. High-speed imaging and fluorescence confocal microscopy of HeLa cells stably expressing enhanced green fluorescent protein fused with markers of cellular compartments were used for this investigation. Soft-shelled microbubbles were observed to enter cells during sonoporation using experimental parameters that led to optimal gene transfer. They interacted with the plasma membrane in a specific area stained with fluorescent cholera subunit B, a marker of lipid rafts. This process was not observed with hard-shelled microbubbles, which were not efficient in gene delivery under our conditions. The plasmid DNA was delivered to late endosomes after 3 h post-sonoporation, and a few were found in the nucleus after 6 h. Gene transfer efficacy was greatly inhibited when cells were treated with chlorpromazine, an inhibitor of the clathrin-dependent endocytosis pathway. In contrast, no significant alteration was observed when cells were treated with filipin III or genistein, both inhibitors of the caveolin-dependent pathway. This study emphasizes that microbubble-cell interactions do not occur randomly during sonoporation; microbubble penetration inside cells affects the efficacy of gene transfer at specific ultrasound settings; and plasmid DNA uptake is an active mechanism that involves the clathrin-dependent pathway.

Evaluation of the potential of doxorubicin loaded microbubbles as a theranostic modality using a murine tumor model

In this study, a novel phospholipid-based microbubble formulation containing doxorubicin and perfluoropropane gas (DLMB) was developed. The DLMBs were prepared by mechanical agitation of a phospholipid dispersion in the presence of perfluoropropane (PFP) gas. An anionic phospholipid, distearoyl phosphatidylglycerol (DSPG) was selected to load doxorubicin in the microbubbles by means of electrostatic interaction. The particle size, zeta potential, echogenicity and stability of the DLMBs were measured. Drug loading was ⩾ 92%. The potential of the DLMBs for use as a theranostic modality was evaluated in tumor bearing mice. Gas chromatography analysis of PFP showed significant enhancement of PFP retention when doxorubicin was used at concentrations of 10-82% equivalent to DSPG. The inhibitory effects on the proliferation of B16BL6 melanoma murine cells in vitro were enhanced using a combination of ultrasound (US) irradiation and DLMBs. Moreover, in vivo DLMBs in combination with (US) irradiation significantly inhibited the growth of B16BL6 melanoma tumor in mice. Additionally, US echo imaging showed high contrast enhancement of the DLMBs in the tumor vasculature. These results suggest that DLMBs could serve as US triggered carriers of doxorubicin as well as tumor imaging agents in cancer therapy.

Kidney-selective gene transfection using anionic bubble lipopolyplexes with renal ultrasound irradiation in mice

This study assessed the ability of a new ultrasound (US) responsive gene delivery carrier, bubble lipopolyplexes, to deliver genes to the kidneys. The bubble lipopolyplexes showed highly selective gene expression in kidney tubules, but only after renal irradiation with US. These bubble lipopolyplexes, however, did not increase the expression of biomarkers of kidney injury, including blood urea nitrogen, serum creatinine, kidney injury molecule-1 mRNA, and clusterin mRNA, or induce any histopathological abnormalities in the kidney. Furthermore, pDNA containing CMV early enhancer/chicken beta-actin promoter prolonged gene expression by the bubble lipopolyplexes in the kidney for 42 days. This novel renal gene delivery method, in which transfection of bubble lipopolyplexes was followed by US irradiation of the kidneys, resulting in cell-selective, high, and long-term gene expression without renal injury in mice, may have future applications in patient treatment.

FROM THE CLINICAL EDITOR

This study demonstrates a novel gene delivery method to the kidneys, utilizing bubble resulting in highly selective gene expression in renal tubules after ultrasound irradiation. In the studied rodent model, there was no evidence for renal damage using this novel delivery system.