Enhancing effects of galactosylated dendrimer/α-cyclodextrin conjugates on gene transfer efficiency

Abstract

To improve in vitro gene transfer efficiency and/or achieve cell-specific gene delivery of polyamidoamine (PAMAM) starburst dendrimer (generation 2, G2) conjugate with O-cyclodextrin (α-CDE conjugate (G2)), we prepared α-CDE conjugate bearing galactose (Gal-α-CDE conjugates) with the various degrees of substitution of the galactose moiety (DSG) as a novel non-viral vector. The agarose gel electrophoretic studies revealed that Gal-α-CDE conjugates formed complexes with plasmid DNA (pDNA) and protected the degradation of pDNA by DNase I, but these effects impaired as the DSG value increased. Dendrimer and α-CDE conjugate exerted pDNA condensation through the complexation, but Gal-α-CDE conjugates did not. Gal-α-CDE conjugate (DSG 4) was found to have much higher gene transfer activity than dendrimer, α-CDE conjugate and Gal-α-CDE conjugates (DSG 8, 15) in HepG2, NIH3T3 and A549 cells, which are independent of the expression of the asialoglycoprotein receptor. Transfection activity of Gal-α-CDE conjugate (DSG 4) was insensitive to the existence of competitors (asialofetuin and galactose) and serum. In addition, no cytotoxicity after transfection of the complex of pDNA with Gal-α-CDE conjugate (DSG 4) was observed. These results suggest the potential use of Gal-α-CDE conjugate (DSG 4) as a non-viral vector in various cells. © 2005 Pharmaceutical Society of Japan.