Liver target delivery of small interfering RNA to the HCV gene by lactosylated cationic liposome

M2 macrophage-targeted metal-polyphenol networks (MPNs) for OPN siRNA delivery and idiopathic pulmonary fibrosis therapy

Idiopathic pulmonary fibrosis (IPF) exhibits extremely high mortality rates. Targeted therapy, which utilizes specific drugs or other substances to identify and attack specific molecular targets in the lesion, holds promise as a potent means of treating IPF. M2 macrophages have been shown to express high levels of osteopontin (OPN) early in the onset of IPF and sustain this high expression to promote the progression of IPF. Intervention in OPN expression can effectively impede the development of fibrosis. While the technology for targeting proteins with siRNA has become increasingly mature, the targeted delivery of siRNA to resident M2 macrophages in the lungs remains challenging. In this study, we developed an engineered self-assembling OPN siRNA carrier complex based on a metal-polyphenol network (luteolin-Zr) and PEG conjugated with an M2 macrophage-targeting peptide (Pery-PEG-M2), termed siOPN@LuZ-M2, for the treatment of pulmonary fibrosis. Consequently, significant therapeutic effects were observed in both bleomycin-induced pulmonary fibrosis mouse models and human precision-cut lung slices (hPCLS) models. Importantly, luteolin, which is slowly released from siOPN@LuZ-M2 within cells, can gradually accumulate in fibrotic lung tissue, exerting an anti-inflammatory effect and further enhancing the treatment of IPF. It is worth mentioning that siOPN@LuZ-M2 can be labeled with 89Zr, allowing for the detection of its in vivo distribution and metabolic behavior via PET-CT. This study presents a promising new image-guided molecular targeting strategy for the treatment of fibrosis.

Coding Therapeutic Nucleic Acids from Recombinant Proteins to Next-Generation Vaccines: Current Uses, Limitations, and Future Horizons

This study aims to highlight the potential use of cTNAs in therapeutic applications. The COVID-19 pandemic has led to significant use of coding therapeutic nucleic acids (cTNAs) in terms of DNA and mRNA in the development of vaccines. The use of cTNAs resulted in a paradigm shift in the therapeutic field. However, the injection of DNA or mRNA into the human body transforms cells into biological factories to produce the necessary proteins. Despite the success of cTNAs in the production of corona vaccines, they have several limitations such as instability, inability to cross biomembranes, immunogenicity, and the possibility of integration into the human genome. The chemical modification and utilization of smart drug delivery cargoes resolve cTNAs therapeutic problems. The success of cTNAs in corona vaccine production provides perspective for the eradication of influenza viruses, Zika virus, HIV, respiratory syncytial virus, Ebola virus, malaria, and future pandemics by quick vaccine design. Moreover, the progress cTNAs technology is promising for the development of therapy for genetic disease, cancer therapy, and currently incurable diseases.

Gene-editing technology, from macromolecule therapeutics to organ transplantation: Applications, limitations, and prospective uses

Gene editing technologies (GETs) could induce gene knockdown or gene knockout for biomedical applications. The clinical success of gene silence by RNAi therapies pays attention to other GETs as therapeutic approaches. This review aims to highlight GETs, categories, mechanisms, challenges, current use, and prospective applications. The different academic search engines, electronic databases, and bibliographies of selected articles were used in the preparation of this review with a focus on the fundamental considerations. The present results revealed that, among GETs, CRISPR/Cas9 has higher editing efficiency and targeting specificity compared to other GETs to insert, delete, modify, or replace the gene at a specific location in the host genome. Therefore, CRISPR/Cas9 is talented in the production of molecular, tissue, cell, and organ therapies. Consequently, GETs could be used in the discovery of innovative therapeutics for genetic diseases, pandemics, cancer, hopeless diseases, and organ failure. Specifically, GETs have been used to produce gene-modified animals to spare human organ failure. Genetically modified pigs are used in clinical trials as a source of heart, liver, kidneys, and lungs for xenotransplantation (XT) in humans. Viral, non-viral, and hybrid vectors have been utilized for the delivery of GETs with some limitations. Therefore, extracellular vesicles (EVs) are proposed as intelligent and future cargoes for GETs delivery in clinical applications. This study concluded that GETs are promising for the production of molecular, cellular, and organ therapies. The use of GETs as XT is still in the early stage as well and they have ethical and biosafety issues.

siRNA-Based Novel Therapeutic Strategies to Improve Effectiveness of Antivirals: An Insight

Since the ground-breaking discovery of RNA interference (RNAi), scientists have made significant progress in the field of small interfering RNA (siRNA) treatments. Due to severe barriers to the therapeutic application of siRNA, nanoparticle technologies for siRNA delivery have been designed. For pathological circumstances such as viral infection, toxic RNA abnormalities, malignancies, and hereditary diseases, siRNAs are potential therapeutic agents. However, systemic administration of siRNAs in vivo remains a substantial issue due to a lack of "drug-likeness" (siRNA are relatively larger than drugs and have low hydrophobicity), physiological obstacles, and possible toxicities. This write-up covers important accomplishment in the field of clinical trials and patents specially based of siRNAs using targeting viruses. Furthermore, it offers deep insight of nanoparticle applied for siRNA delivery and strategies to improve the effectiveness of antivirals.

Advances in Nanoliposomes for the Diagnosis and Treatment of Liver Cancer

The mortality rate of liver cancer is gradually increasing worldwide due to the increasing risk factors such as fatty liver, diabetes, and alcoholic cirrhosis. The diagnostic methods of liver cancer include ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI), among others. The treatment of liver cancer includes surgical resection, transplantation, ablation, and chemoembolization; however, treatment still faces multiple challenges due to its insidious development, high rate of recurrence after surgical resection, and high failure rate of transplantation. The emergence of liposomes has provided new insights into the treatment of liver cancer. Due to their excellent carrier properties and maneuverability, liposomes can be used to perform a variety of functions such as aiding in imaging diagnoses, combinatorial therapies, and integrating disease diagnosis and treatment. In this paper, we further discuss such advantages.

The significance of bioengineered nanoplatforms against SARS-CoV-2: From detection to genome editing

COVID-19 outbreak can impose serious negative impacts on the infrastructures of societies including the healthcare systems. Despite the increasing research efforts, false positive or negative results that may be associated with serologic or even RT-PCR tests, inappropriate or variable immune response, and high rates of mutations in coronavirus may negatively affect virus detection process and effectiveness of the vaccines or drugs in development. Nanotechnology-based research attempts via developing state-of-the-art techniques such as nanomechatronics ones and advanced materials including the sensors for detecting the pathogen loads at very low concentrations or site-specific delivery of therapeutics, and real-time protections against the pandemic outbreaks by nanorobots can provide outstanding biomedical breakthroughs. Considering the unique characteristics of pathogens particularly the newly-emerged ones and avoiding the exaggerated optimism or simplistic views on the prophylactic and therapeutic approaches including the one-size-fits-all ones or presenting multiple medications that may be associated with synergistic toxicities rather than enhanced efficiencies might pave the way towards the development of more appropriate treatment strategies with reduced safety concerns. This paper highlights the significance of nanoplatforms against the viral disorders and their capabilities of genome editing that may facilitate taking more appropriate measures against SARS-CoV-2.

In vitro and in vivo antitumor effects of lupeol-loaded galactosylated liposomes

Lupeol liposomes, modified with Gal-PEG-DSPE, were developed following a thin-film dispersion method. Then, the morphology, physicochemical properties, and in vitro release properties of those liposomes were investigated. The scanning electron microscopic images showed that most of the liposomes were spherical particles; they were similar in size and uniformly dispersed. Both lupeol liposomes and Gal-lupeol liposomes exhibited an average particle size of about 100 nm. The encapsulation efficiency was greater than 85%. The encapsulation efficiency of lupeol liposome and Gal-lupeol liposome, stored with 15% sucrose as glycoprotein for 6 months, was higher than 80%; although the particle size increased, they remained within 200 nm. The cell-uptake study demonstrated that the Gal-lupeol-liposome uptake efficiency was the highest in HepG2 cells. The HepG2 cells treated with the Gal-lupeol liposomes had higher apoptotic efficiency than the lupeol liposome and free lupeol. After HepG2 cells were treated with Gal-lupeol liposome, the expressions of AKT/mTOR-related proteins (p-AKT308 and p-AKT473) were also significantly reduced than the lupeol-liposome and free lupeol group. The in vivo targeting studies showed that Gal-NR-L exhibited liver-targeting effects on FVB mice. The pharmacodynamic study was performed by transfecting AKT and c-MET via the high-pressure tail vein of FVB mice. After Gal-lupeol-L administration, the liver index and liver weight of mice were less than those non-targeted group. The histopathological study showed that the lobular structure in the mice liver was clearer, the vacuoles were more obvious, and the cytoplasm was more abundant after Gal-lupeol-L administration. Also, the qRT-PCR study showed that AFP, GPC3, and EpCAM mRNA expression levels were significantly lower than those non-targeted lupeol-liposomes.

Nanotheranostics against COVID-19: From multivalent to immune-targeted materials

Destructive impacts of COVID-19 pandemic worldwide necessitates taking more appropriate measures for mitigating virus spread and development of the effective theranostic agents. In general, high heterogeneity of viruses is a major challenging issue towards the development of effective antiviral agents. Regarding the coronavirus, its high mutation rates can negatively affect virus detection process or the efficiency of drugs and vaccines in development or induce drug resistance. Bioengineered nanomaterials with suitable physicochemical characteristics for site-specific therapeutic delivery, highly-sensitive nanobiosensors for detection of very low virus concentration, and real-time protections using the nanorobots can provide roadmaps towards the imminent breakthroughs in theranostics of a variety of diseases including the COVID-19. Besides revolutionizing the classical disinfection procedures, state-of-the-art nanotechnology-based approaches enable providing the analytical tools for accelerated monitoring of coronavirus and associated biomarkers or drug delivery towards the pulmonary system or other affected organs. Multivalent nanomaterials capable of interaction with multivalent pathogens including the viruses could be suitable candidates for viral detection and prevention of further infections. Besides the inactivation or destruction of the virus, functionalized nanoparticles capable of modulating patient's immune response might be of great significance for attenuating the exaggerated inflammatory reactions or development of the effective nanovaccines and medications against the virus pandemics including the COVID-19.

Current Transport Systems and Clinical Applications for Small Interfering RNA (siRNA) Drugs

Small interfering RNAs (siRNAs) are an attractive new agent with potential as a therapeutic tool because of its ability to inhibit specific genes for many conditions, including viral infections and cancers. However, despite this potential, many challenges remain, including off-target effects, difficulties with delivery, immune responses, and toxicity. Traditional genetic vectors do not guarantee that siRNAs will silence genes in vivo. Rational design strategies, such as chemical modification, viral vectors, and non-viral vectors, including cationic liposomes, polymers, nanocarriers, and bioconjugated siRNAs, provide important opportunities to overcome these challenges. We summarize the results of research into vector delivery of siRNAs as a therapeutic agent from their design to clinical trials in ophthalmic diseases, cancers, respiratory diseases, and liver virus infections. Finally, we discuss the current state of siRNA delivery methods and the need for greater understanding of the requirements.

Nanoparticles in Antiviral Therapy

In addition to general unavailability of specific antiviral therapeutics for a variety of viral diseases, usage of most antiviral drugs is linked to their limited solubility in aqueous media, short half-life time, and inadequate penetration to specified anatomic compartments. Accordingly, there is continuous effort to improve physicochemical characteristics of existing antiviral drugs. Since nanomaterials display remarkable physical and chemical properties, high surface area to volume ratio, and increased reactivity, new approaches for antiviral therapies include combinations of nanomaterials and current antiviral agents. Multivalent nanostructures, polymers, dendrimers, and liposomes can establish multivalent binding interactions with many biological systems and thus can target pathogenic interactions. There are reports about anitiviral activities of different metal nanoparticles, especially silver nanoparticles and their potential for treatment, prophylaxis, and control of viral infections. Integration of classic antiviral drugs, in the form of multiple ligands, onto nanostructures provides the advantages by creating a high local concentration of active molecules. This article will summarize the antiviral activity of different nanoparticle-based approaches currently available for the treatment of viral infections, and it will discuss metal nanoparticles as possible future antiviral drugs.

Achieving long-term stability of lipid nanoparticles: examining the effect of pH, temperature, and lyophilization

The broadest clinical application of siRNA therapeutics will be facilitated by drug-loaded delivery systems that maintain stability and potency for long times under ambient conditions. In the present study, we seek to better understand the stability and effect of storage conditions on lipidoid nanoparticles (LNPs), which have been previously shown by our group and others to potently deliver RNA to various cell and organ targets both in vitro and in vivo. Specifically, this study evaluates the influence of pH, temperature, and lyophilization on LNP efficacy in HeLa cells. When stored under aqueous conditions, we found that refrigeration (2°C) kept LNPs the most stable over 150 days compared to storage in the −20°C freezer or at room temperature. Because the pH of the storage buffer was not found to influence stability, it is suggested that the LNPs be stored under physiologically appropriate conditions (pH 7) for ease of use. Although aggregation and loss of efficacy were observed when LNPs were subjected to freeze–thaw cycles, their stability was retained with the use of the cryoprotectants, trehalose, and sucrose. Initially, lyophilization of the LNPs followed by reconstitution in aqueous buffer also led to reductions in efficacy, most likely due to aggregation upon reconstitution. Although the addition of ethanol to the reconstitution buffer restored efficacy, this approach is not ideal, as LNP solutions would require dialysis prior to use. Fortunately, we found that the addition of trehalose or sucrose to LNP solutions prior to lyophilization facilitated room temperature storage and reconstitution in aqueous buffer without diminishing delivery potency.

Pharmacokinetics and biodistribution of recently-developed siRNA nanomedicines

Small interfering RNA (siRNA) is a promising drug candidate, expected to have broad therapeutic potentials toward various diseases including viral infections and cancer. With recent advances in bioconjugate chemistry and carrier technology, several siRNA-based drugs have advanced to clinical trials. However, most cases address local applications or diseases in the filtering organs, reflecting remaining challenges in systemic delivery of siRNA. The difficulty in siRNA delivery is in large part due to poor circulation stability and unfavorable pharmacokinetics and biodistribution profiles of siRNA. This review describes the pharmacokinetics and biodistribution of siRNA nanomedicines, focusing on those reported in the past 5years, and their pharmacological effects in selected disease models such as hepatocellular carcinoma, liver infections, and respiratory diseases. The examples discussed here will provide an insight into the current status of the art and unmet needs in siRNA delivery.

Conjugates of small targeting molecules to non-viral vectors for the mediation of siRNA

To use siRNA (small interfering RNA) for gene therapy, a gene delivery system is often necessary to overcome several challenging requirements including rapid excretion, low stability in blood serum, non-specific accumulation in tissues, poor cellular uptake and inefficient intracellular release. Active and/or passive targeting should help the delivery system to reach the desired tissue or cell, to be internalized, and to deliver siRNA to the cytoplasm so that siRNA can inhibit protein synthesis. This review covers conjugates of small targeting molecules and non-viral delivery systems for the mediation of siRNA, with a focus on their transfection properties in order to help the development of new and efficient siRNA delivery systems, as the therapeutic solutions of tomorrow.

STATEMENT OF SIGNIFICANCE

The delivery of siRNA into cells or tissues remains to be a challenge for its applications, an alternative strategy for siRNA delivery systems is direct conjugation of non-viral vectors with targeting moieties for cellular delivery. In comparison to macromolecules, small targeting molecules have attracted great attention due to their many potential advantages including significant simplicity and ease of production, good repeatability and biodegradability. This review will focus on the most recent advances in the delivery of siRNA using conjugates of small targeting molecules and non-viral delivery systems. Based the editor's suggestions, we hope the revised manuscript could provide more profound understanding to the conjugates of targeting molecules to vectors for mediation of siRNA.

Target delivery of small interfering RNAs with vitamin E-coupled nanoparticles for treating hepatitis C

RNA interference (RNAi) represents a promising strategy for the treatment of HCV infection. However, the development of an effective system for in vivo delivery of small interfering RNA (siRNA) to target organ remains a formidable challenge. Here, we develop a unique nanoparticle platform (VE-DC) composed of α-tocopherol (vitamin E) and cholesterol-based cationic liposomes (DOTAP-Chol) for systemic delivery of siRNAs to the liver. A HCV-replicable cell line, Huh7.5.1-HCV, and a transient HCV core expressing cell line, Huh7.5.1-Core, were constructed and used to assess the in vitro anti-HCV activity of VE-DC/siRNAs. A transient in vivo HCV model was also constructed by hydrodynamic injection of pCDNA3.1(+)-3FLAG-Core (pCore-3FLAG) plasmid expressing core protein or pGL3-5′UTR-luciferase (pGL3-5′UTR-luc) plasmid expressing luciferase driven by HCV 5′UTR. Nanoscale VE-DC/siRNA was intravenously injected to assess the liver-targeting property as well as antiviral activity. The nanoscale VE-DC effectively exerted an anti-HCV activity in the in vitro cell models. Post-administration of VE-DC/siRNAs also effectively delivered siRNAs to the liver, suppressing core protein production and firefly luciferase activity, without inducing an innate immunity response or off-target and toxicity effects. The VE-DC platform has high potential as a vehicle for delivery of siRNAs to the liver for gene therapy for targeting hepatitis C.

Nanostructures for the Inhibition of Viral Infections

Multivalent interactions are omnipresent in biology and confer biological systems with dramatically enhanced affinities towards different receptors. Such multivalent binding interactions have lately been considered for the development of new therapeutic strategies against bacterial and viral infections. Multivalent polymers, dendrimers, and liposomes have successfully targeted pathogenic interactions. While a high synthetic effort was often needed for the development of such therapeutics, the integration of multiple ligands onto nanostructures turned to be a viable alternative. Particles modified with multiple ligands have the additional advantage of creating a high local concentration of binding molecules. This review article will summarize the different nanoparticle-based approaches currently available for the treatment of viral infections.

Small RNA- and DNA-based gene therapy for the treatment of liver cirrhosis, where we are?

Chronic liver diseases with different aetiologies rely on the chronic activation of liver injuries which result in a fibrogenesis progression to the end stage of cirrhosis and liver failure. Based on the underlying cellular and molecular mechanisms of a liver fibrosis, there has been proposed several kinds of approaches for the treatment of liver fibrosis. Recently, liver gene therapy has been developed as an alternative way to liver transplantation, which is the only effective therapy for chronic liver diseases. The activation of hepatic stellate cells, a subsequent release of inflammatory cytokines and an accumulation of extracellular matrix during the liver fibrogenesis are the major obstacles to the treatment of liver fibrosis. Several targeted strategies have been developed, such as antisense oligodeoxynucleotides, RNA interference and decoy oligodeoxynucleotides to overcome this barriers. With this report an overview will be provided of targeted strategies for the treatment of liver cirrhosis, and particularly, of the targeted gene therapy using short RNA and DNA segments.

Lipid nanoparticles as carriers for RNAi against viral infections: current status and future perspectives

The efforts made to develop RNAi-based therapies have led to productive research in the field of infections in humans, such as hepatitis C virus (HCV), hepatitis B virus (HBV), human immunodeficiency virus (HIV), human cytomegalovirus (HCMV), herpetic keratitis, human papillomavirus, or influenza virus. Naked RNAi molecules are rapidly digested by nucleases in the serum, and due to their negative surface charge, entry into the cell cytoplasm is also hampered, which makes necessary the use of delivery systems to exploit the full potential of RNAi therapeutics. Lipid nanoparticles (LNP) represent one of the most widely used delivery systems for in vivo application of RNAi due to their relative safety and simplicity of production, joint with the enhanced payload and protection of encapsulated RNAs. Moreover, LNP may be functionalized to reach target cells, and they may be used to combine RNAi molecules with conventional drug substances to reduce resistance or improve efficiency. This review features the current application of LNP in RNAi mediated therapy against viral infections and aims to explore possible future lines of action in this field.

Delivery of RNAi therapeutics: work in progress

RNA interference (RNAi) therapeutics appear to offer substantial opportunities for future therapy. However, post-administration RNAi effectors are typically unable to reach disease target cells in vivo without the assistance of a delivery system or vector. The main focus of this review is on lipid-based nanoparticle (LNP) delivery systems in current research and development that have at least been shown to act as effective delivery systems for functional delivery of RNAi effectors to disease target cells in vivo. The potential utility of these LNP delivery systems is growing rapidly, and LNPs are emerging as the preferred synthetic delivery systems in preclinical studies and current nonviral RNAi effector clinical trials. Moreover, studies on LNP-mediated delivery in vivo are leading to the emergence of useful biophysical parameters and physical organic chemistry rules that provide a framework for understanding in vivo delivery behaviors and outcomes. These same parameters and rules should also suggest ways and means to develop next generations of LNPs with genuine utility and long-term clinical viability.

Functional magnetic nanoparticles for non-viral gene delivery and MR imaging

Gene therapy is becoming a promising strategy to treat various kinds of genetic and acquired diseases. However, the development of safe, efficient, and targetable gene delivery systems remains a major challenge in gene therapy. The unique material characteristics of magnetic nanoparticles (MNPs), including high surface area, facile surface modification, controllable size, and excellent magnetic properties, make them promising candidates for gene delivery. The engineered MNPs with modifiable functional surfaces and bioactive cores can result in several advantageous diagnostic and therapeutic properties including enhanced magnetic resonance imaging (MRI) signal intensity, long permeation and retention in the circulatory system, specific delivery of therapeutic genes to target sites. In this review, the updated research on the preparation and surface modification of MNPs for gene delivery is summarized.

Efficient Biodistribution and Gene Silencing in the Lung epithelium via Intravenous Liposomal Delivery of siRNA

RNA interference (RNAi) may provide a therapeutic solution to many pulmonary epithelium diseases. However, the main barrier to the clinical use of RNAi remains the lack of efficient delivery vectors. Research has mainly concentrated on the intranasal route of delivery of short interfering RNA (siRNA) effector molecules for the treatment of respiratory diseases. However, this may be complicated in a diseased state due to the increased fluid production and tissue remodeling. Therefore, we investigated our hydration of a freeze-dried matrix (HFDM) formulated liposomes for systemic delivery to the lung epithelium. Here, we show that 45 ± 2% of epithelial murine lung cells receive siRNA delivery upon intravenous (IV) liposomal administration. Furthermore, we demonstrate that liposomal siRNA delivery resulted in targeted gene and protein knockdown throughout the lung, including lung epithelium. Taken together, this is the first description of lung epithelial delivery via cationic liposomes, and provides a proof of concept for the use of IV liposomal RNAi delivery to specifically knockdown targeted genes in the respiratory system. This approach may provide an attractive alternate therapeutic delivery strategy for the treatment of lung epithelium diseases.

Trans-resveratrol loaded chitosan nanoparticles modified with biotin and avidin to target hepatic carcinoma

Conventional liver targeted system focuses on delivering drugs to liver, bringing toxicity on hepatic normal tissues. The purpose of this study is to construct a new system capable of specially targeting to hepatic carcinoma instead of the whole liver. Based on the fact that nanoparticles (NPs) bound with either biotin or avidin tend to accumulate in tumors and avidin-attached reagents were quickly eliminated from blood circulation and assembled in liver, trans-resveratrol loaded chitosan nanoparticles (CS-NPs), CS-NPs with the surface modified either by biotin (B-CS-NPs) or by both biotin and avidin (A-B-CS-NPs) were prepared and their physiochemical properties were investigated. The in vitro release profiles of the three NPs all conformed to bioexponential equation. Pharmacokinetic experiment indicated that A-B-CS-NPs rapidly assembled in liver after injection, with the highest liver targeting index of 2.70, while the modification of biotin attenuated the liver targeting ability of NPs. Inhibitory study on HepG2 cells declared that compared to trans-resveratrol solution and CS-NPs, both B-CS-NPs and A-B-CS-NPs significantly improved the anticancer activity. When incubated with HepG2 cells at high concentration for longer time, A-B-CS-NPs exhibited superior cytotoxicity than B-CS-NPs. This study exclaims that A-B-CS-NPs may be a potent drug delivery vector specially targeting to hepatic carcinoma.

Novel targeted liposomes deliver sirna to hepatocellular carcinoma cells in vitro

Liposomes form a major class of non-viral vectors for short interfering RNA delivery, however tissue and cell-specific targeting are additional requirements in the design of short interfering RNA delivery systems with a therapeutic potential. Selective delivery of liposomes to hepatocytes may be achieved by directing complexes to the asialoglycoprotein receptor, which is expressed on hepatocytes, and which displays high affinity for the β-d-galactopyranosyl moiety. We aimed to show that the d-galactopyranosyl ring in direct β-glycosidic link to cholesterol, when formulated into liposomes with 3β[N-(N',N'-dimethylaminopropane) carbamoyl] cholesterol (Chol-T) or its quaternary trimethylammonium analogue (Chol-Q), may promote targeted delivery of cytotoxic short interfering RNA to the human hepatoma cell line HepG2 via the asialoglycoprotein receptor. Liposome-short interfering RNA interactions were characterized by electron microscopy, dye displacement, gel retardation and nuclease assays. Stable short interfering RNA-protective lipoplexes were formed at N/P ratios in the range 5:1-7:1. Targeted lipoplex 4 achieved high transfection efficiencies at 50 nm short interfering RNA (70%) and <10% in a competition assay, whilst untargeted complexes reached low levels at the same concentration (<25%). Transfection efficiencies of all lipoplexes in the asialoglycoprotein receptor-negative cell line HEK293 under the same conditions were low. Lipoplexes containing cholesteryl-β-d-galactopyranoside may therefore form the basis for the development of useful hepatotropic short interfering RNA delivery vectors.

Inhibition of hepatitis C virus replication by intracellular delivery of multiple siRNAs by nanosomes

Sustained antiviral responses of chronic hepatitis C virus (HCV) infection have improved recently by the use of direct-acting antiviral agents along with interferon (IFN)-α and ribavirin. However, the emergence of drug-resistant variants is expected to be a major problem. We describe here a novel combinatorial small interfering RNA (siRNA) nanosome-based antiviral approach to clear HCV infection. Multiple siRNAs targeted to the highly conserved 5'-untranslated region (UTR) of the HCV genome were synthesized and encapsulated into lipid nanoparticles called nanosomes. We show that siRNA can be repeatedly delivered to 100% of cells in culture using nanosomes without toxicity. Six siRNAs dramatically reduced HCV replication in both the replicon and infectious cell culture model. Repeated treatments with two siRNAs were better than a single siRNA treatment in minimizing the development of an escape mutant, resulting in rapid inhibition of viral replication. Systemic administration of combinatorial siRNA-nanosomes is well tolerated in BALB/c mice without liver injury or histological toxicity. As a proof-of-principle, we showed that systemic injections of siRNA nanosomes significantly reduced HCV replication in a liver tumor-xenotransplant mouse model of HCV. Our results indicate that systemic delivery of combinatorial siRNA nanosomes can be used to minimize the development of escape mutants and inhibition of HCV infection.

Stability of lyophilized siRNA nanosome formulations

The goal of this study is to evaluate the stability of lyophilized siRNA formulations. The gene silencing efficiency of a stored lyophilized siRNA formulation (i.e. siRNA nanosomes) was evaluated in interferon-α (IFN-α) resistant hepatitis C virus (HCV) at different time points up to three months in an in vitro cell culture model and compared with freshly prepared siRNA formulations. Novel siRNA sequences were encapsulated within nanosize liposomes following condensation with protamine sulfate. The siRNA encapsulated nanosomes were lyophilized and stored at 4 °C for 3 months, along with liquid liposomes (L) and lyophilized liposome powder (P) which were subsequently used to prepare siRNA nanosomes (L) and siRNA nanosomes (P), respectively at different time points. Physiochemical and biological properties of all three formulations were compared at different time points up to 3 months. The particle size of the stored siRNA nanosomes (642 ± 25 nm) was considerably larger initially in comparison with the liquid liposomes (134 ± 5 nm) and lyophilized liposomes (118 ± 3). However, the particle size gradually became smaller over time (413 ± 128 nm by the third month). The zeta potential of all three formulations was initially very high (> +40 mV), followed by a gradual decrease over time. The amount of siRNA in the stored siRNA nanosomes decreased ∼18 % during the 3 month storage period (1.16 ± 0.03 nmol initially on day 1 vs. 0.95 ± 0.04 nmol after 3 months). With respect to biological potency, all three formulations were significantly effective to knock-down HCV throughout the storage time. The cell viability was well-maintained throughout this period. Thus, this study indicates that the stored lyophilized siRNA formulation is as effective as the fresh preparation and that long-term storage could be a viable option to treat deadly diseases such as cancer and viral infection.

Development and optimization of nanosomal formulations for siRNA delivery to the liver

The objective of this study is to develop an effective siRNA delivery system for successful delivery to the liver for the treatment of HCV. Nanosize liposomes (nanosomes) have been prepared using a mixture of cholesterol and DOTAP. A functional siRNA was encapsulated into nanosomes following condensation with protamine sulfate. The delivery of siRNA was optimized in an in vitro cell culture system. The efficacy of the formulations was evaluated by measuring functional gene silencing and cytotoxicity. Encapsulation of siRNA ≥ 7.4 nM resulted in successful delivery of siRNA to nearly 100% of cells. The formulations containing lipid-to-siRNA ratio ≥ 10.56:1 instantly cleared approximately 85% of HCV while maintaining cell viability at about 90%. The formulations were sonicated to further reduce the particle size. The size of these formulations was decreased up to 100 nm. However, there were no significant changes observed in zeta potential, or in siRNA encapsulation and integrity following sonication. The sonicated formulations also showed higher liver hepatocytes deposition and gene silencing properties. This study therefore provides a novel approach of siRNA delivery to liver hepatocytes, which can also be applied to treat HCV in chronic liver diseases.

Preparation, characterization, and efficient transfection of cationic liposomes and nanomagnetic cationic liposomes

Purpose

Cationic liposomes (CLs) are composed of phospholipid bilayers. One of the most important applications of these particles is in drug and gene delivery. However, using CLs to deliver therapeutic nucleic acids and drugs to target organs has some problems, including low transfection efficiency in vivo. The aim of this study was to develop novel CLs containing magnetite to overcome the deficiencies.

Materials and methods

CLs and magnetic cationic liposomes (MCLs) were prepared using the freeze-dried empty liposome method. Luciferase-harboring vectors (pGL3) were transferred into liposomes and the transfection efficiencies were determined by luciferase assay. Firefly luciferase is one of most popular reporter genes often used to measure the efficiency of gene transfer in vivo and in vitro. Different formulations of liposomes have been used for delivery of different kinds of gene reporters. Lipoplex (liposome–plasmid DNA complexes) formation was monitored by gel retardation assay. Size and charge of lipoplexes were determined using particle size analysis. Chinese hamster ovary cells were transfected by lipoplexes (liposome-pGL3); transfection efficiency and gene expression level was evaluated by luciferase assay.

Results

High transfection efficiency of plasmid by CLs and novel nanomagnetic CLs was achieved. Moreover, lipoplexes showed less cytotoxicity than polyethyleneimine and Lipofectamine^™.

Conclusion

Novel liposome compositions (1,2-dipalmitoyl-sn-glycero-3-phosphocholine [DPPC]/dioctadecyldimethylammonium bromide [DOAB] and DPPC/cholesterol/DOAB) with high transfection efficiency can be useful in gene delivery in vitro. MCLs can also be used for targeted gene delivery, due to magnetic characteristic for conduction of genes or drugs to target organs.

Inhibition of full length hepatitis C virus particles of 1a genotype through small interference RNA

Background

Hepatitis C virus (HCV), a member of the Flaviviridae family of viruses, is a major cause of chronic hepatitis, liver cirrhosis and hepatocellular carcinoma. Currently, the only treatment available consists of a combination of Pegylated interferon alpha (INF-α) and ribavirin, but only half of the patients treated show a sufficient antiviral response. Thus there is a great need for the development of new treatments for HCV infections. RNA interference (RNAi) represents a new promising approach to develop effective antiviral drugs and has been extremely effective against HCV infection.

Results

This study was design to assess or explore the silencing effect of small interference RNAs (siRNAs) against full length HCV particles of genotype 1a. In the present study six 21-bp siRNAs were designed against different regions of HCV structural genes (Core, E1 and E2). Selected siRNAs were labeled as Csi 301, Csi 29, E1si 52, E1si 192, E2si 86 and E2si 493. Our results demonstrated that siRNAs directed against HCV core gene showed 70% reduction in viral titer in HCV infected liver cells. Moreover, siRNAs against E1 and E2 envelop genes showed a dramatic reduction in HCV viral RNA, E2si 86 exhibited 93% inhibition, while E1si 192, E2si 493 and E1si 52 showed 87%, 80%, and 66% inhibition respectively. No significant inhibition was detected in cells transfected with the negative control siRNA.

Conclusion

Our results suggested that siRNAs targeted against HCV structural genes efficiently silence full length HCV particles and provide an effective therapeutic option against HCV infection.

Inhibition of hepatitis C virus genotype 3a by siRNAs targeting envelope genes

Hepatitis C virus (HCV) genotype 3a is considered a significant risk factor for the development of liver diseases and hepatocellular carcinoma for most of the cases in Pakistan. Because of the limited efficiency of the current therapy, RNA interference (RNAi), which results in sequence-specific degradation of HCV RNA, has potential as a powerful alternative molecular therapeutic approach. The envelope genes (E1 and E2) of HCV come in immediate contact with cells during infection and therefore might be a relevant target for new drug development. In the present study, the expression of E1 and E2 genes of HCV genotype 3a was dramatically reduced at both the mRNA and protein level using gene-specific small interfering RNAs (siRNA) when compared to mock-transfected and cells treated with control siRNAs. The potential of siRNAs to inhibit HCV-3a replication in serum-infected Huh-7 cells was also demonstrated by combined treatment of siRNAs against the E1 and E2 genes, which resulted in a significant decrease in HCV viral copy number. This clearly demonstrates that the RNAi-mediated silencing of HCV E1 and E2 is among the first of its type for the development of an effective siRNA-based therapeutic option against HCV-3a.

Investigating a new generation of ribozymes in order to target HCV

For a long time nucleic acid-based approaches directed towards controlling the propagation of Hepatitis C Virus (HCV) have been considered to possess high potential. Towards this end, ribozymes (i.e. RNA enzymes) that specifically recognize and subsequently catalyze the cleavage of their RNA substrate present an attractive molecular tool. Here, the unique properties of a new generation of ribozymes are taken advantage of in order to develop an efficient and durable ribozyme-based technology with which to target HCV (+) RNA strands. These ribozymes resulted from the coupling of a specific on/off adaptor (SOFA) to the ribozyme domain derived from the Hepatitis Delta Virus (HDV). The former switches cleavage activity "on" solely in the presence of the desired RNA substrate, while the latter was the first catalytic RNA reported to function naturally in human cells, specifically in hepatocytes. In order to maximize the chances for success, a step-by-step approach was used for both the design and the selection of the ribozymes. This approach included the use of both bioinformatics and biochemical methods for the identification of the sites possessing the greatest potential for targeting, and the subsequent in vitro testing of the cleavage activities of the corresponding SOFA-HDV ribozymes. These efforts led to a significant improvement in the ribozymes' designs. The ability of the resulting SOFA-HDV ribozymes to inhibit HCV replication was further examined using a luciferase-based replicon. Although some of the ribozymes exhibited high levels of cleavage activity in vitro, none appears to be a potential long term inhibitor in cellulo. Analysis of recent discoveries in the cellular biology of HCV might explain this failure, as well as provide some ideas on the potential limits of using nucleic acid-based drugs to control the propagation of HCV. Finally, the above conclusions received support from experiments performed using a collection of SOFA-HDV ribozymes directed against HCV (-) strands.

RNAi as a new therapeutic strategy against HCV

Hepatitis C virus is a major cause of liver associated diseases all over the world. Irrespective of the significant advances in the current therapy, drugs and vaccines are restricted with many factors such as toxicity, complexity, cost and resistance. New technologies particularly RNA interference (RNAi) mediated by small interfering RNA (siRNA) have become more and more interesting and effective therapeutic entities to silence pathogenic gene products associated with disease, including cancer, viral infections and autoimmune disorders. RNAi works at a posttranscriptional level by targeting mRNA as a mean for inhibiting the synthesis of the encoded protein. Several reports have indicated the efficiency and specificity of synthetic and vector based siRNAs inhibiting HCV replication. In the present review, we focused on the recent development in the potential use and issues regarding siRNA as a therapy for HCV.

Targeted RNA interference for hepatic fibrosis

Hepatic fibrosis is a common consequence in patients with chronic liver damage. To date, no agent has been approved for the treatment of hepatic fibrosis. RNA interference (RNAi) is known to be a powerful tool for post-transcriptional gene silencing and has opened new avenues in gene therapy. The problems of lack of cell specificity in vivo and subsequently the occurrence of side effects has hampered the development of hepatic fibrosis treatment. To overcome these shortcomings, several targeted strategies have been developed, such as hydrodynamics-based approaches, local administration, cell-type-selective ligands and cell-type-specific promoters or enhancers, etc. Here, we provide an overview of targeted strategies for the treatment of hepatic fibrosis, and particularly, targeted RNAi for hepatic fibrosis.

Nonviral gene vector formation in monodispersed picolitre incubator for consistent gene delivery

A novel picolitre incubator based microfluidic system for consistent nonviral gene carrier formulation is presented. A cationic lipid-based carrier is the most attractive nonviral solution for delivering plasmid DNA, shRNA, or drugs for pharmaceutical research and RNAi applications. The size of the cationic lipid and DNA complex (CL-DNA), or the lipoplex, is one of the important variations for consistency of gene transfection. CL-DNA size, in turn, may be controlled by factors such as the cationic lipid and DNA mixing order, mixing rate, and mixture incubation time. The Picolitre Microfluidic Reactor and Incubator (PMRI) system described here is able to control these parameters in order to create homogeneous CL-DNA. Compared with conventional CL-DNA preparation techniques involving hand-shaking or vortexing, the PMRI system demonstrates a greater ability to constantly and uniformly mix cationic lipids and DNA simultaneously. After mixing in the picolitre droplet reactors, the cationic lipid and DNA is incubated within the picolitre incubator to form CL-DNA. The PMRI generates a narrower size distribution band, while also turning the sample loading, mixing and incubation steps into an integrated process enabling the consistent formation of CL-DNA. The coefficient of variation (CV) of transfection efficiency is 0.05 and 0.30 for PMRI-based and conventional methods, respectively. In addition, this paper demonstrates that the gene transfection efficiency of lipoplex created in the PMRI is more reproducible.

The consideration of synthetic short interfering RNA for therapeutic use

Small RNA molecules can act as regulators of post-transcriptional gene silencing and can target any given protein via the RNA interference pathway. This leads to the high expectation of small interference RNA (siRNA) as a therapeutic platform. Many companies and organisations are active in this development, which consequently forces siRNA's pharmacokinetic studies because pharmacokinetics plays an important role in elucidating the pharmacodynamic and toxicological mechanism of test articles. In particular, pharmacokinetics is mandatory in investigational new drug application in many countries. Some pre-clinical and clinical pharmacokinetic results have already been published and the fate of siRNA compounds in biological matrices has been explored in depth. The elucidation of the siRNA's metabolism improves the rational design of siRNA for disease control. This review focuses on the study of synthetic siRNA pharmacokinetics, the challenges of siRNA as a therapeutic agent and the strategies involved for improving siRNA bioavailability from the view of siRNA metabolism.

Antisense inhibitors, ribozymes, and siRNAs

The current standard of care for the treatment of hepatitis C virus infection, pegylated interferon-alpha and ribavirin, is costly, associated with significant side effects, and effective in only 50% of patients. There is therefore a need for the development of novel antiviral therapies. One such approach involves the application of gene silencing technologies, including antisense oligonucleotides, ribozymes, RNA interference, and aptamers. However, despite great scientific advances over the past decade, and promising in vitro data, several significant challenges continue to limit the translation of this technology to the clinical setting. This review provides a concise update of the current literature.

Targeted delivery of siRNA against hepatitis C virus by apolipoprotein A-I-bound cationic liposomes

BACKGROUND/AIMS

Hepatitis C virus (HCV) is one of the major human hepatic RNA viruses. Recently, we developed a liver-specific siRNA delivery technology using DTC-Apo composed of cationic liposomes (DTC) and apolipoprotein A-I (apo A-I). Here, we investigated whether DTC-Apo nanoparticles can systemically deliver siRNA into mouse hepatocytes expressing HCV proteins and inhibit their expression efficiently.

METHODS

A transient HCV model was constructed by hydrodynamic injection of plasmid DNA expressing viral structural proteins under hepatic control region and alpha1-antitrypsin promoter elements. Using this model, DTC-Apo containing HCV-core-specific siRNA was intravenously injected to assess antiviral activity as well as the duration of silencing.

RESULTS

Post-administration of DTC-Apo/HCV-specific siRNA at a dose of 2mg siRNA/kg inhibited viral gene expression by 65-75% in the liver on day 2. Improved activity (95% knockdown on day 2) without immunotoxicity was obtained by 2'-OMe-modification at two U sequences on its sense strand. Notably, the gene silencing effect of the modified siRNA was still maintained at day 6, while the unmodified one lost RNAi activity after day 4.

CONCLUSIONS

Our results suggest that DTC-Apo liposome is a highly potential delivery vehicle to transfer therapeutic siRNA especially targeting HCV to the liver.

Tumor regression in mice by delivery of Bcl-2 small interfering RNA with pegylated cationic liposomes

The pharmacokinetics and antitumor activity of pegylated small interfering RNA (siRNA)/cationic liposome complexes were studied after systemic administration to mice. We designed pegylated-lipid carriers for achieving increased plasma concentrations of RNA and hence improved accumulation of RNA in tumors by the enhanced permeability and retention effect. We compared the pharmacokinetics of siRNA complexed with liposomes incorporating pegylated lipids with longer (C-17 or C-18), shorter (C-12 to C-16), or unsaturated (C-18:1) acyl chains. When longer acyl chains were used, the plasma concentrations of siRNA obtained were dramatically higher than when shorter or unsaturated chains were used. This may be explained by the higher gel-to-liquid-crystalline phase-transition temperature (Tc) of lipids with longer acyl chains, which may form more rigid liposomes with reduced uptake by the liver. We tested a siRNA that is sequence specific for the antiapoptotic bcl-2 mRNA complexed with a pegylated liposome incorporating a C-18 lipid (PEG-LIC) by i.v. administration in a mouse model of human prostate cancer. Three-fold higher accumulation of RNA in the tumors was achieved when PEG-LIC rather than nonpegylated liposomes was used, and sequence-specific antitumor activity was observed. Our siRNA/PEG-LIC complex showed no side effects on repeated administration and the strength of its antitumor activity may be attributed to its high uptake by the tumors. Pegylation of liposomes improved the plasma retention, uptake by s.c. tumors, and antitumor activity of the encapsulated siRNA. PEG-LIC is a promising candidate for siRNA cancer therapy.

siRNA, miRNA, and shRNA: in vivo Applications

RNA interference (RNAi), an accurate and potent gene-silencing method, was first experimentally documented in 1998 in Caenorhabditis elegans by Fire et al., who subsequently were awarded the 2006 Nobel Prize in Physiology/Medicine. Subsequent RNAi studies have demonstrated the clinical potential of synthetic small interfering RNAs (siRNAs) or short hairpin RNAs (shRNAs) in dental diseases, eye diseases, cancer, metabolic diseases, neurodegenerative disorders, and other illnesses. siRNAs are generally from 21 to 25 base-pairs (bp) in length and have sequence-homology-driven gene-knockdown capability. RNAi offers researchers an effortless tool for investigating biological systems by selectively silencing genes. Key technical aspects—such as optimization of selectivity, stability, in vivo delivery, efficacy, and safety—need to be investigated before RNAi can become a successful therapeutic strategy. Nevertheless, this area shows a huge potential for the pharmaceutical industry around the globe. Interestingly, recent studies have shown that the small RNA molecules, either indigenously produced as microRNAs (miRNAs) or exogenously administered synthetic dsRNAs, could effectively activate a particular gene in a sequence-specific manner instead of silencing it. This novel, but still uncharacterized, phenomenon has been termed ‘RNA activation’ (RNAa). In this review, we analyze these research findings and discussed the in vivo applications of siRNAs, miRNAs, and shRNAs.

Sustained delivery of siRNAs targeting viral infection by cell-degradable multilayered polyelectrolyte films

Gene silencing by RNA interference (RNAi) has been shown to represent a recently discovered approach for the treatment of human diseases, including viral infection. A major limitation for the success of therapeutic strategies based on RNAi has been the delivery and shortlasting action of synthetic RNA. Multilayered polyelectrolyte films (MPFs), consisting of alternate layer-by-layer deposition of polycations and polyanions, have been shown to represent an original approach for the efficient delivery of DNA and proteins to target cells. Using hepatitis C virus infection (HCV) as a model, we demonstrate that siRNAs targeting the viral genome are efficiently delivered by MPFs. This delivery method resulted in a marked, dose-dependent, specific, and sustained inhibition of HCV replication and infection in hepatocyte-derived cells. Comparative analysis demonstrated that delivery of siRNAs by MPFs was more sustained and durable than siRNA delivery by standard methods, including electroporation or liposomes. The antiviral effect of siRNA-MPFs was reversed by a hyaluronidase inhibitor, suggesting that active degradation of MPFs by cellular enzymes is required for siRNA delivery. In conclusion, our results demonstrate that cell-degradable MPFs represent an efficient and simple approach for sustained siRNA delivery targeting viral infection. Moreover, this MPF-based delivery system may represent a promising previously undescribed perspective for the use of RNAi as a therapeutic strategy for human diseases.

Harnessing the RNA interference pathway to advance treatment and prevention of hepatocellular carcinoma

Primary liver cancer is the fifth most common malignancy in the world and is a leading cause of cancer-related mortality. Available treatment for hepatocellular carcinoma (HCC), the commonest primary liver cancer, is rarely curative and there is a need to develop therapy that is more effective. Specific and powerful gene silencing that can be achieved by activating RNA interference (RNAi) has generated enthusiasm for exploiting this pathway for HCC therapy. Many studies have been carried out with the aim of silencing HCC-related cellular oncogenes or the hepatocarcinogenic hepatitis B virus (HBV) and hepatitis C virus (HCV). Proof of principle studies have demonstrated promising results, and an early clinical trial assessing RNAi-based HBV therapy is currently in progress. Although the data augur well, there are several significant hurdles that need to be overcome before the goal of RNAi-based therapy for HCC is realized. Particularly important are the efficient and safe delivery of RNAi effecters to target malignant tissue and the limitation of unintended harmful non-specific effects.