Influence of the chitosan nature on the transfection efficacy of DNA-loaded nanoparticles after hydrodynamic administration in mice

Physicochemical properties of polymers: An important system to overcome the cell barriers in gene transfection

Delivery of the macromolecules including DNA, miRNA, and antisense oligonucleotides is typically mediated by carriers due to the large size and negative charge. Different physical (e.g., gene gun or electroporation), and chemical (e.g., cationic polymer or lipid) vectors have been already used to improve the efficiency of gene transfer. Polymer-based DNA delivery systems have attracted special interest, in particular via intravenous injection with many intra- and extracellular barriers. The recent progress has shown that stimuli-responsive polymers entitled as multifunctional nucleic acid vehicles can act to target specific cells. These nonviral carriers are classified by the type of stimulus including reduction potential, pH, and temperature. Generally, the physicochemical characterization of DNA-polymer complexes is critical to enhance the transfection potency via protection of DNA from nuclease digestion, endosomal escape, and nuclear localization. The successful clinical applications will depend on an exact insight of barriers in gene delivery and development of carriers overcoming these barriers. Consequently, improvement of novel cationic polymers with low toxicity and effective for biomedical use has attracted a great attention in gene therapy. This article summarizes the main physicochemical and biological properties of polyplexes describing their gene transfection behavior, in vitro and in vivo. In this line, the relative efficiencies of various cationic polymers are compared.

Propellant-based inhalers for the non-invasive delivery of genes via oral inhalation

In this work we describe the development of a propellant-based, portable oral inhalation platform for the pulmonary delivery of genes. A core-shell strategy is utilized to efficiently disperse cationic-polymer-DNA nanoparticles in hydrofluoroalkane propellants, and to generate aerosols from the corresponding pressurized metered-dose inhaler formulations (pMDIs) that have excellent aerosol characteristics, suitable for deep lung deposition. The engineered polyplexes and core-shell structures were fully characterized, and their ability to transfect model lung alveolar epithelium cells in vitro was demonstrated. We also show that the propellant does not affect the biological activity of the plasmid DNA, and that the core-shell formulations have no in vitro cytotoxicity. The relevance of this work stems from the fact that pMDIs are the least expensive and most widely used portable oral inhalation devices, and are thus promising platforms for targeting genes to the lungs for the treatment of medically relevant diseases including asthma, cystic fibrosis, chronic obstructive pulmonary disease, and lung cancer.

Chitosanase-based method for RNA isolation from cells transfected with chitosan/siRNA nanocomplexes for real-time RT-PCR in gene silencing

Chitosan, a well known natural cationic polysaccharide, has been successfully implemented in vitro and in vivo as a nonviral delivery system for both plasmid DNA and siRNA. While using chitosan/siRNA polyplexes to knock down specific targets, we have underestimated the effect of nucleic acids binding to chitosan when extracting RNA for subsequent quantitative PCR evaluation of silencing. In vitro transfection using chitosan/siRNA-based polyplexes reveals a very poor recovery of total RNA especially when using low cell numbers in 96 well plates. Here, we describe a method that dramatically enhances RNA extraction from chitosan/siRNA-treated cells by using an enzymatic treatment with a type III chitosanase. We show that chitosanase treatment prior to RNA extraction greatly enhances the yield and the integrity of extracted RNA. This method will therefore eliminate the bias associated with lower RNA yield and integrity when quantifying gene silencing of chitosan-based systems using quantitative real time PCR.