siRNA Delivery with Chitosan: Influence of Chitosan Molecular Weight, Degree of Deacetylation, and Amine to Phosphate Ratio on in Vitro Silencing Efficiency, Hemocompatibility, Biodistribution, and in Vivo Efficacy.

Chitosan (CS) shows in vitro and in vivo efficacy for siRNA delivery but with contradictory findings for incompletely characterized systems. For understanding which parameters produce effective delivery, a library of precisely characterized chitosans was produced at different degrees of deacetylation (DDAs) and average molecular weights (M). Encapsulation and transfection efficiencies were characterized in vitro.

Chitosans for delivery of nucleic acids.

Alternatives to efficient viral vectors in gene therapy are desired because of their poor safety profiles. Chitosan is a promising non-viral nucleotide delivery vector because of its biocompatibility, biodegradability, low immunogenicity and ease of manufacturing. Since the transfection efficiency of chitosan polyplexes is relatively low compared to viral counterparts, there is an impetus to gain a better understanding of the structure-performance relationship.

Low molecular weight chitosan nanoparticulate system at low N:P ratio for nontoxic polynucleotide delivery.

Chitosan, a natural polymer, is a promising system for the therapeutic delivery of both plasmid DNA and synthetic small interfering RNA. Reports attempting to identify the optimal parameters of chitosan for synthetic small interfering RNA delivery were inconclusive with high molecular weight at high amine-to-phosphate (N:P) ratios apparently required for efficient transfection. Here we show, for the first time, that low molecular weight chitosan (LMW-CS) formulations at low N:P ratios are suitable for the in vitro delivery of small interfering RNA.

Chitosan-based therapeutic nanoparticles for combination gene therapy and gene silencing of in vitro cell lines relevant to type 2 diabetes.

Glucagon like peptide 1 (GLP-1), a blood glucose homeostasis modulating incretin, has been proposed for the treatment of type 2 diabetes mellitus (T2DM). However, native GLP-1 pharmacokinetics reveals low bioavailability due to degradation by the ubiquitous dipeptydil peptidase IV (DPP-IV) endoprotease. In this study, the glucosamine-based polymer chitosan was used as a cationic polymer-based in vitro delivery system for GLP-1, DPP-IV resistant GLP-1 analogues and siRNA targeting DPP-IV mRNA.

Excess polycation mediates efficient chitosan-based gene transfer by promoting lysosomal release of the polyplexes.

The optimal ratio of the polycation's amine to DNA phosphate group (N:P) for efficient polymer-based transfection always employs excess polycation versus DNA. Most of the excess polycation remains free in solution, unassociated with the polyplexes, but is essential for efficient transfection. The mechanism by which excess polycation increases transfection efficiency is not identified.