A Chapter of the book

"Carbohydrate polymers: development, properties and applications"

R.Ito and Y. Matsuo, eds.

Nova Science Publishers, Inc., 2009.

Hauppauge NY, USA

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Chitosans: new vectors for gene therapy

Riccardo A.A. Muzzarelli

During the last quinquennium, chitosan has suddenly gained importance as a plasmid vector to be used in gene therapy in alternative to unsafe viral vectors. The main characteristics that qualify chitosan for this role are its spontaneous reactivity with DNA and oligonucleotides in general, the protection of DNA against enzymatic destruction by nucleases, the slow release of DNA, the capacity to penetrate into tissues by opening tight junctions of cells, besides its full biocompatibility with human cells and its safe assimilation in the body. The chitosan chemistry has been refined in order to impart to chitosan better solubility in physiological media, by acting on its cationicity and hydrophilicity / hydrophobicity, or combining it with poly(ethyleneimine), polyethylene glycol and derivatives, or conjugating it with cell-specific ligands. The transfection efficacy of said modified chitosans was greatly improved compared to plain chitosan. In order to understand the fate of internalized vector-DNA complexes within cells, fluorophores including the green fluorescent protein have been conjugated with DNA or with chitosan. After the exceptionally good performances of chitosans as functional wound dressing materials and drug carriers, it appears that the involvement of chitins and chitosans in gene therapy will develop into an additional exceptional achievement for this class of polysaccharides.