In vitro gene delivery mediated by chitosan. Effect of pH, serum, and molecular mass of chitosan on the transfection efficiency

Aminopolysaccharides such as chitosan and polygalactosamine (pGalN) were us ed to transfer luciferase plasmid into tumor cells. Chitosan largely enhanc ed the transfection efficiency of luciferase plasmid (pGL3), while pGalN di d not at all. Transfection efficiencies of the pGL3/chitosan complexes were dependent on pH of culture medium, stoicheometry of pGL3:chitosan, serum, and molecular mass of chitosan. Transfection efficiency at pH 6.9 was highe r than that at pH7.6. Optimum charge ratio of the pGL3:chitosan was 1:5. Ch itosan polymer of 15 and 52 kDa largely promoted luciferase activities. Tra nsfection efficiency mediated by chitosan of > 100 kDa was less than that b y chitosan of 15 and 52 kDa. Heptamer (1.3 kDa) did nut show any gene expre ssion. Cationic liposome (lipofectin)-associated gene expression was inhibi ted by serum, while chitosan showed resistance to serum.;(C) 2001 Published by Elsevier Science Ltd.