Chitosans for delivery of nucleic acids

Abstract

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. Recent progress in preparation and characterisation has enabled coupling analysis of chitosans structural parameters that has led to increased TE by tailoring of chitosan's structure. In this review, we summarize the recent advances that have lead to a more rational design of chitosan polyplexes. We present an integrated review of all major areas of chitosan-based transfection, including preparation, chitosan and polyplexes physicochemical characterisation, in vitro and in vivo assessment. In each, we present the obstacles to efficient transfection and the strategies adopted over time to surmount these impediments.

Low Molecular Weight Chitosan (LMWC)-based Polyplexes for pDNA Delivery: From Bench to Bedside

“…However, the two main structural parameters that affect the final properties of the formed polyplexes are the M W and the DDA of the Ch, as it has been explained in the introduction section, being highly deacetylation LMWC the most suitable for gene therapy purposes [22,36]. Therefore, a more detailed study of their mechanisms of formation is needed to circumvent this situation, which will resolve several contradictory results reported in the literature regarding the influence of formulation parameters on the resulting polyplexes properties [10]. There are also a significant number of works that present an incomplete description of the polyplex preparation method, which limits comparison with other studies.…”

“…Although cationic lipids are the most studied vectors at the moment, natural cationic polymers have shown promising results and they are being studied as a less toxic alternative to lipid based non-viral systems [5]. Among natural polymers, chitosan (Ch) is one of the most studied polysaccharides [6][7][8][9][10] as it is biocompatible, biodegradable and non-toxic [11]. Chitin is a nitrogenous polysaccharide derived from the exoskeleton of crustacean, insects and fungi.…”

“…For a successful non-viral gene therapy an optimized balance between the DNA protection and intracellular DNA unpacking is required [18]. Polyplexes elaborated with high molecular weight chitosans (HMWC) (>150 KDa) [10] show better DNA binding, which is beneficial for the protection of DNA. However, the release of the DNA cargo once inside the cell is restricted due to the high stability of the polyplexes.…”

Elucidating the role of free polycationic chains in polycation gene carriers by free chains of polyethylenimine or N,N,N-trimethyl chitosan plus a certain polyplex

“…PEI/DNA polyplex (PEI-P) shows low colloidal stability, 21 and the DNA in PEI-P can be easily displaced by heparin. 22 Chitosan has poor solubility at neutral pH, which translates into colloidally unstable polyplexes 5 and triggers the sedimentation of free chitosan chains under physiological conditions. Therefore, a stable polyplex is required to understand the mechanism of polycation gene carriers.…”

“…1,2 Polycations usually involve synthetic polymers, such as polyethylenimine (PEI) 3 and polylysine, 4 and naturally derived polymers, such as chitosan and its derivatives. 5 The positively charged polycations can form complexes (known as polyplexes) with the negatively charged deoxyribonucleic acid (DNA) by electrostatic interaction. Consequently, DNA can be protected from nuclease degradation and delivered to the targets.…”