Identification of critical points in colloidal delivery systems for intravenous administration and intracellular delivery of nucleic acids as therapeutic agents (original) (raw)
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Clinical applications of genetic therapies, including delivery of short, interfering RNAs (siRNAs) for RNA interference (RNAi), are limited due to the difficulty of delivering nucleic acids to specific cells of interest while at the same time minimizing toxicity and immunogenicity. The use of cationic polymers to deliver nucleic acid therapeutics has the potential to address these complex issues but is currently limited by low delivery efficiencies. While cell culture studies have shown that some polymers can be used to deliver siRNAs and achieve silencing, it is still not clear what physical or chemical properties are needed to ensure that the polymers form active polymer-siRNA complexes. In this study, we used multicolor fluorescence confocal microscopy to analyze the cellular uptake of siRNAs delivered by novel propargyl glycolide polymeric nanoparticles (NPs). Delivery by these vehicles was compared to delivery by linear polyethyleneimine (LPEI) and Lipofectamine 2000 (LF2K), which are both known as effective delivery vehicles for siRNAs. Our results showed that when LF2K and LPEI were used, large quantities of siRNA were delivered rapidly, presumably overwhelming the basal levels of mRNA to initiate silencing. In contrast, our novel polymeric NPs showed delivery of siRNAs but at concentrations that were initially too low to achieve silencing. Nonetheless, the exceptionally low cytotoxicity of our NPs, and the simplicity with which they can be modified, makes them good candidates for further study to optimize their delivery profiles and, in turn, achieve efficient silencing.
siRNA Drug Delivery by Biodegradable Polymeric Nanoparticles
Journal of Nanoscience and Nanotechnology, 2006
RNA interference (RNAi) is an emerging technology in which the introduction of double-stranded RNA (dsRNA) into a diverse range of organisms and cell types causes degradation of the complementary mRNA. It offers a broad spectrum of applications in both biological and medical research. Small interference RNA (siRNA) was recently explored for its therapeutical potential. However, the drug delivery of siRNA oligos is very novel and is in great need of future research. To this end, a biodegradable poly(D,L-lactide-co-glycolide) (PLGA) nanoparticle drug carrier system was prepared to load siRNA oligos with desired physicochemical properties. The nanoparticles were characterized by scanning electron microscopy and laser diffraction particle sizer. The delivery of siRNA into the targeted 293T cells was observed using fluorescent-labeled double-stranded Cy3-oligos. The model siRNA oligos, si-GFP-RNA, were also successfully loaded into PLGA nanoparticles and delivered in 293T cells. The gene...
Phospholipid–polyethylenimine conjugate-based micelle-like nanoparticles for siRNA delivery
Drug Delivery and Translational Research, 2010
Gene silencing using small interfering RNA (siRNA) is a promising therapeutic strategy for the treatment of various diseases, in particular, cancer. Recently, our group reported on a novel gene carrier, the micelle-like nanoparticle (MNP), based on the combination of a covalent conjugate of phospholipid and polyethylenimine (PLPEI) with polyethylene glycol (PEG) and lipids. These long-circulating MNPs loaded with plasmid DNA-mediated gene expression in distal tumors after systemic administration in vivo. In the current study, we investigated the potential of MNPs for siRNA delivery. MNPs were prepared by condensing siRNA with PLPEI at a nitrogen/phosphate ratio of 10, where the binding of siRNA is complete. The addition of a PEG/lipid coating to the PLPEI complexes generated particles with sizes of ca. 200 nm and a neutral surface charge compared with positively charged PLPEI polyplexes without the additional coating. MNPs protected the loaded siRNA against enzymatic digestion and enhanced the cellular uptake of the siRNA payload. MNPs carrying green fluorescent protein (GFP)-targeted siRNA effectively downregulated the gene in cells that stably express GFP. Finally, MNPs were non-toxic at a wide range of concentrations and for different cell lines.
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Small interfering RNA (siRNA) therapeutics have potential advantages over traditional small molecule drugs such as high specificity and the ability to inhibit otherwise "undruggable" targets. However, siRNAs have short plasma half-lives in vivo, can induce a cytokine response, and show poor cellular uptake. Formulating siRNA into nanoparticles offers two advantages: enhanced siRNA stability against nuclease degradation beyond what chemical modification alone can provide; and improved site-specific delivery that takes advantage of the enhanced permeability and retention (EPR) effect. Existing delivery systems generally suffer from poor delivery to tumors. Here we describe the formation and biological activity of polymeric nanopharmaceuticals (PNPs) based on biocompatible and biodegradable poly(lactic-co-glycolic acid) (PLGA) conjugated to siRNA via an intracellular cleavable disulfide linker (PLGA-siRNA). Additionally, these PNPs contain (1) PLGA conjugated to polyethylene ...
Nanoparticle-based delivery of small interfering RNA: challenges for cancer therapy
International Journal of Nanomedicine, 2012
During recent decades there have been remarkable advances and profound changes in cancer therapy. Many therapeutic strategies learned at the bench, including monoclonal antibodies and small molecule inhibitors, have been used at the bedside, leading to important successes. One of the most important advances in biology has been the discovery that small interfering RNA (siRNA) is able to regulate the expression of genes, by a phenomenon known as RNA interference (RNAi). RNAi is one of the most rapidly growing fields of research in biology and therapeutics. Much research effort has gone into the application of this new discovery in the treatment of various diseases, including cancer. However, even though these molecules may have potential and strong utility, some limitations make their clinical application difficult, including delivery problems, side effects due to off-target actions, disturbance of physiological functions of the cellular machinery involved in gene silencing, and induction of the innate immune response. Many researchers have attempted to overcome these limitations and to improve the safety of potential RNAi-based therapeutics. Nanoparticles, which are nanostructured entities with tunable size, shape, and surface, as well as biological behavior, provide an ideal opportunity to modify current treatment regimens in a substantial way. These nanoparticles could be designed to surmount one or more of the barriers encountered by siRNA. Nanoparticle drug formulations afford the chance to improve drug bioavailability, exploiting superior tissue permeability, payload protection, and the "stealth" features of these entities. The main aims of this review are: to explain the siRNA mechanism with regard to potential applications in siRNA-based cancer therapy; to discuss the possible usefulness of nanoparticlebased delivery of certain molecules for overcoming present therapeutic limitations; to review the ongoing relevant clinical research with its pitfalls and promises; and to evaluate critically future perspectives and challenges in siRNA-based cancer therapy.
Applications of Lipidic and Polymeric Nanoparticles for siRNA Delivery
Antisense Therapy [Working Title]
The antisense technology that emerged with the discovery of RNA interference nearly 20 years ago has gained a significant place in gene therapy. siRNA, one of two important components of RNA interference, efficiently downregulates gene expression in human cells, so it has the potential to eradicate disease. siRNA delivery systems, which can be applied both systemically and locally in different diseases, have gained significant importance. Naked small RNAs can be delivered directly to cells, but because of their instability, exposure to enzyme degradation, and difficulties in reaching/entering the target cell or tissue in blood stream, these initiatives are failing. For this reason, the method of delivery or encapsulation of siRNA is usually required. Various nanoparticles, nanocapsules, emulsions, micelle systems, metal ion nanoparticles, and nanoconjugates have been used for siRNA delivery. In these transport systems, lipidic and polymeric systems are very attractive due to their advantages such as being biodegradable and biocompatible, safety, being able to electrostatically bind to RNA, long-term stability, well-illuminated structure and features, simple and easy production, etc. Issues such as particle size, zeta potential, and stability of siRNA-loaded system should be taken into consideration in the development of siRNA delivery systems.
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Advances in nanotechnology have provided powerful and efficient tools in the development of cancer diagnosis and therapy. There are numerous nanocarriers that are currently approved for clinical use in cancer therapy. In recent years, biodegradable polymer nanoparticles have attracted a considerable attention for their ability to function as a possible carrier for target-specific delivery of various drugs, genes, proteins, peptides, vaccines, and other biomolecules in humans without much toxicity. This review will specifically focus on the recent advances in polymer-based nanocarriers for various drugs and small silencing RNA's loading and delivery to treat different types of cancer.
Nanoscale Small Interfering RNA Delivery Systems For Personalized Cancer Therapy
Nanoparticles represent particularly attractive delivery systems for small interfering RNA (siRNA) and may provide the foundation for rational design and formulation of RNAi-triggering nanomedicines. siRNA can be delivered with a therapeutic intent using lipid-based delivery platforms such as stable nucleic acid lipid particles (SNALP) with a lipid bilayer containing cationic as well as fusogenic lipids and a diffusible PEG-lipid coat, polymers, cationic complexes, recombinant fusion proteins, conjugates, or polyconjugates. Several investigators have reported preclinical or early clinical proof of concept studies demonstrating that systemic delivery of siRNA nanoparticles targeting specific gene transcripts can elicit biologic responses. Therapeutic nanoparticles containing siRNA targeting specific genes that contribute to the aggressiveness and/or radiochemotherapy resistance of cancer cells may facilitate a paradigm shift in modern cancer therapy.
European Journal of Pharmaceutics and Biopharmaceutics, 2009
The success of the application of new therapeutic methods based on RNA interfering strategies requires the in vivo delivery of active ODN or siRNA down to the intracellular compartment of the target cells. This article aims to review the studies related to the formulation of RNA interfering agents in polymer nanocarriers. It will present the different types of polymer nanocarriers used as well as the biological activity of the resulting ODN and siRNA loaded nanocarriers. As will be explained, the part of the in vitro studies provided useful data about the intracellular delivery of the formulated RNA interfering agents. Investigations performed in vivo have considered animal models of different relevant diseases. Results from these investigations have clearly demonstrated the interest of several polymer nanocarriers tested so far to deliver active RNA interfering effectors in vivo making possible their administration by the intravenous route.
Non-condensing polymeric nanoparticles for targeted gene and siRNA delivery
International journal of pharmaceutics, 2012
Gene therapy has shown a tremendous potential to benefit patients in a variety of disease conditions. However, finding a safe and effective systemic delivery system is the major obstacle in this area. Although viral vectors showed promise for high transfection rate, the immunogenicity associated with these systems has hindered further development. As an alternative to viral gene delivery, this review focuses on application of novel safe and effective non-condensing polymeric systems that have shown high transgene expression when administered systemically or by the oral route. Type B gelatin-based engineered nanocarriers were evaluated for passive and active tumor-targeted delivery and transfection using both reporter and therapeutic plasmid DNA. Additionally, we have shown that nanoparticles-in-microsphere oral system (NiMOS) can efficiently deliver reporter and therapeutic gene constructs in the gastrointestinal tract. Additionally, there has been a significant recent interest in t...