The offset effect of a hyaluronic acid coating to cationic carriers containing siRNA: Alleviated cytotoxicity and retained gene silencing in vitro

Recent Progress in Nucleic Acid Pulmonary Delivery toward Overcoming Physiological Barriers and Improving Transfection Efficiency

Pulmonary delivery of therapeutic agents has been considered the desirable administration route for local lung disease treatment. As the latest generation of therapeutic agents, nucleic acid has been gradually developed as gene therapy for local diseases such as asthma, chronic obstructive pulmonary diseases, and lung fibrosis. The features of nucleic acid, specific physiological structure, and pathophysiological barriers of the respiratory tract have strongly affected the delivery efficiency and pulmonary bioavailability of nucleic acid, directly related to the treatment outcomes. The development of pharmaceutics and material science provides the potential for highly effective pulmonary medicine delivery. In this review, the key factors and barriers are first introduced that affect the pulmonary delivery and bioavailability of nucleic acids. The advanced inhaled materials for nucleic acid delivery are further summarized. The recent progress of platform designs for improving the pulmonary delivery efficiency of nucleic acids and their therapeutic outcomes have been systematically analyzed, with the application and the perspectives of advanced vectors for pulmonary gene delivery.

Polymer-lipid hybrid nanomedicines to deliver siRNA in and against glioblastoma cells

Small interfering RNA (siRNA) holds great potential to treat many difficult-to-treat diseases, but its delivery remains the central challenge. This study aimed at investigating the suitability of polymer-lipid hybrid nanomedicines (HNMeds) as novel siRNA delivery platforms for locoregional therapy of glioblastoma. Two HNMed formulations were developed from poly(lactic-co-glycolic acid) polymer and a cationic lipid: 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) or 3ß-[N-(N',N'-dimethylaminoethane)-carbamoyl]cholesterol (DC-Chol). After characterization of the HNMeds, a model siRNA was complexed onto their surface to form HNMed/siRNA complexes. The physicochemical properties and siRNA binding ability of complexes were assessed over a range of nitrogen-to-phosphate (N/P) ratios to optimize the formulations. At the optimal N/P ratio of 10, complexes effectively bound siRNA and improved its protection from enzymatic degradation. Using the NIH3T3 mouse fibroblast cell line, DOTAP-based HNMeds were shown to possess higher cytocompatibility in vitro over the DC-Chol-based ones. As proof-of-concept, uptake and bioefficacy of formulations were also assessed in vitro on U87MG human glioblastoma cell line expressing luciferase gene. Complexes were able to deliver anti-luciferase siRNA and induce a remarkable suppression of gene expression. Noteworthy, the effect of DOTAP-based formulation was not only about three-times higher than DC-Chol-based one, but also comparable to lipofectamine model transfection reagent. These findings set the basis to exploit this nanosystem for silencing relevant GB-related genes in further in vitro and in vivo studies.

Inhaled siRNA Formulations for Respiratory Diseases: From Basic Research to Clinical Application

The development of siRNA technology has provided new opportunities for gene-specific inhibition and knockdown, as well as new ideas for the treatment of disease. Four siRNA drugs have already been approved for marketing. However, the instability of siRNA in vivo makes systemic delivery ineffective. Inhaled siRNA formulations can deliver drugs directly to the lung, showing great potential for treating respiratory diseases. The clinical applications of inhaled siRNA formulations still face challenges because effective delivery of siRNA to the lung requires overcoming the pulmonary and cellular barriers. This paper reviews the research progress for siRNA inhalation formulations for the treatment of various respiratory diseases and summarizes the chemical structural modifications and the various delivery systems for siRNA. Finally, we conclude the latest clinical application research for inhaled siRNA formulations and discuss the potential difficulty in efficient clinical application.

Developing spray-freeze-dried particles containing a hyaluronic acid-coated liposome-protamine-DNA complex for pulmonary inhalation

The liposome-protamine-DNA complex (LPD) is an effective cationic carrier of various nucleic acid constructs such as plasmid DNA and small interfering RNA (siRNA). Hyaluronic acid coated on LPD (LPDH) reduces cytotoxicity and maintains the silencing effect of LPD-encapsulated siRNA. Herein, we aim to develop LPD- or LPDH-containing spray-freeze-dried particles (SFDPs) for therapeutic delivery of siRNA to the lungs. LPD- or LPDH-containing SFDPs (LPD- or LPDH-SFDPs) were synthesized and their structure and function as gene carriers were evaluated using physical and biological methods. The particle size of LPDH, but not of LPD, was constant after re-dispersal from the SFDPs and the amount of siRNA encapsulated in LPDH was larger than that in LPD after re-dispersal from the SFDPs. The in vitro pulmonary inhalation properties of LPDH-SFDPs and LPD-SFDPs were almost the same. The cytotoxicity of LPDH-SFDPs in human umbilical vein endothelial cells (HUVEC) was greatly decreased compared with that of LPD-SFDPs. In addition, Bcl-2 siRNA in LPDH-SFDPs had a significant gene silencing effect in human lung cancer cells (A549), whereas Bcl-2 siRNA in LPD-SFDPs had little effect. These results indicate that compared with LPD, LPDH is more useful for developing SFDPs for siRNA pulmonary inhalation.

Natural Polysaccharides for siRNA Delivery: Nanocarriers Based on Chitosan, Hyaluronic Acid, and Their Derivatives

Natural polysaccharides are frequently used in the design of drug delivery systems due to their biocompatibility, biodegradability, and low toxicity. Moreover, they are diverse in structure, size, and charge, and their chemical functional groups can be easily modified to match the needs of the final application and mode of administration. This review focuses on polysaccharidic nanocarriers based on chitosan and hyaluronic acid for small interfering RNA (siRNA) delivery, which are highly positively and negatively charged, respectively. The key properties, strengths, and drawbacks of each polysaccharide are discussed. In addition, their use as efficient nanodelivery systems for gene silencing applications is put into context using the most recent examples from the literature. The latest advances in this field illustrate effectively how chitosan and hyaluronic acid can be modified or associated with other molecules in order to overcome their limitations to produce optimized siRNA delivery systems with promising in vitro and in vivo results.

Cellular responses of hyaluronic acid-coated chitosan nanoparticles

In recent years, nanotechnology has been proven to offer promising biomedical applications for in vivo diagnostics and drug delivery, stressing the importance of thoroughly investigating the biocompatibility of potentially translatable nanoparticles (NPs). Herein, we report the cellular responses of uncoated chitosan NPs (CS NPs) and hyaluronic acid-coated chitosan NPs (HA-CS NPs) when introduced into Chinese hamster ovary cells (CHO-K1) in a dose-dependent manner (2.5, 0.25, 0.025, 0.0025, and 0.00025 mg mL-1) at two time points (24 and 48 h). MTS assay, cell proliferation, showed a decrease in the viability of cells when treated with 0.25 and 2.5 mg mL-1 CS NPs. When exposed to high doses of CS NPs, the lactate dehydrogenase (LDH) enzyme started to leak out of the cells and the cellular levels of mitochondrial potentials were significantly reduced accompanied by a high production of intracellular reactive oxygen species (ROS). Our study provides molecular evidence of the biocompatibility offered by HA-CS NPs, through ROS scavenging capabilities rescuing cells from the oxidative stress, showing no observed cellular stress and thereby revealing the promising effect of anionic hyaluronic acid to significantly reduce the cytotoxicity of CS NPs. Our findings are important to accelerate the translation and utilization of HA-CS NPs in drug delivery, demonstrating the pronounced effect of surface modifications on modulating the biological responses.