Chitosan as a nonviral gene delivery system. Structure–property relationships and characteristics compared with polyethylenimine in vitro and after lung administration in vivo

Abstract

Chitosan is a natural cationic linear polymer that has recently emerged as an alternative nonviral gene delivery system. We have established the relationships between the structure and the properties of chitosan-pDNA polyplexes in vitro. Further, we have compared polyplexes of ultrapure chitosan (UPC) of preferred molecular structure with those of optimised polyethylenimine (PEI) polyplexes in vitro and after intratracheal administration to mice in vivo. Chitosans in which over two out of three monomer units carried a primary amino group formed stable colloidal polyplexes with pDNA. Optimized UPC and PEI polyplexes protected the pDNA from serum degradation to approximately the same degree, and they gave a comparable maximal transgene expression in 293 cells. In contrast to PEI, UPC was non toxic at escalating doses. After intratracheal administration,

Gene delivery to the lung using protein/polyethylenimine/plasmid complexes

“…Quantities of plasmid of 2 g or larger result in a reduction in gene expression with this formulation. Numerous investigations into the mechanisms of plasmid delivery suggest that PEI is taken up by cells with or without DNA, and that larger quantities can be toxic in vitro 23,24 and in vivo. 25 We have observed this in vitro where concentrations of PEI in the range of 80 nmol/ml or greater do show cytotoxic effects, and associated with this toxicity is a decline in gene expression as measured by the percentage of GFP-positive cells or total luciferase per well (Orson, unpublished).…”

Chitosan as a non-viral co-transfection system in a cystic fibrosis cell line

“…The first report on using chitosan to complex DNA and evaluate it as a non-viral delivery system for a plasmid dates from 1995 (Mumper et al, 1995). Driven by electrostatic interactions, chitosanpDNA complexes have been used for transfection of mammalian cells both in vitro and in vivo (Koping-Hoggard et al, 2001;Romøren et al, 2003;Vauthier et al, 2014). Nevertheless, results of transfection efficiency using chitosan-based systems are strongly dependent on chitosan properties (e.g., molecular weight and the relative amount of N-acetylglucosamine units, namely degree of acetylation (DA)) (Lavertu et al, 2006;Santos-Carballal et al, 2015;Strand et al, 2005).…”

“…Chitosan has been reported as a suitable candidate for transmucosal administration of drugs (Grenha et al, 2010). In addition, it has been observed that after intratracheal administration, the complexes using CS were found in the mid-airways, and transgene expression was observed in epithelial cells (Koping-Hoggard et al, 2001). In general, gene therapy, based on the use of chitosan as a non-viral vector, has been extensively considered in the last decade or so (Gomes et al, 2014).…”

Improved chitosan-mediated gene delivery based on easily dissociated chitosan polyplexes of highly defined chitosan oligomers

“…Previous studies have shown that chitosan polyplexes exhibit low cytotoxicity [12][13][14][15] and are suitable for gene delivery to mucosal tissues such as the intestine and the lung in vivo. 12,[16][17][18][19][20][21] In most of these studies, commercially available chitosans of high molecular weights (100-400 kDa) were used. These chitosans form extremely stable polyplexes with DNA, which delays the release of the pDNA, and the physical shape of the polyplexes is dominated by aggregates.…”

“…These chitosans form extremely stable polyplexes with DNA, which delays the release of the pDNA, and the physical shape of the polyplexes is dominated by aggregates. 12,17,20 Other pharmaceutical drawbacks with high-molecular-weight chitosans include their low solubility at physiological pH 22 and their viscosity enhancing properties at concentrations suitable for in vivo gene therapy. 12 We speculated that these drawbacks could be eliminated if chitosans of lower molecular weights were used, that is, chitosans that were long enough to form stable polyplexes, but sufficiently short to be soluble at neutral pH, give a reduced viscosity, form less aggregated shapes more typical for multivalent ions, and form more easily dissociated polyplexes.…”