Effects of Structure of Polyamidoamine Dendrimer on Gene Transfer Efficiency of the Dendrimer Conjugate with α-Cyclodextrin.

Kihara, Fumihiro; Arima, Hidetoshi; Tsutsumi, Toshihito; Hirayama, Fumitoshi; Uekama, Kaneto.

Faculty of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan.

Abstract

To improve gene transfer activity of a new nonviral vector, a polyamidoamine dendrimer (G2) conjugate with α-cyclodextrin (α-CDE conjugate (G2)), we prepd. α-CDE conjugates with dendrimer having different generations (G3 and G4), and their gene transfer activities were compared with those of α-CDE conjugate (G2) and TransFast, a novel transfection reagent. α-CDE conjugates (G2, G3, and G4) formed the complexes with pDNA, changing the z-potential and particle size of pDNA complexes and the protection of pDNA from DNase I in a charge ratio-dependent manner, although their differences at higher charge ratios (vector/pDNA) were small. The gene transfer activity of α-CDE conjugates (G2, G3, and G4) was higher than that of the corresponding dendrimer alone in NIH3T3 and RAW264.7 cells. Of these CDE conjugates, α-CDE conjugate (G3) had a superior gene transfer activity which was comparable to that of TransFast in NIH3T3 cells. The intracellular distribution of pDNA after application of the pDNA complex with α-CDE conjugate (G3) to NIH3T3 cells was different from that with dendrimer alone (G3), although the cellular assocn. of pDNA was almost comparable among all vectors. α-CDE conjugate (G3) strongly interacted with a fluorescence probe, 2-(p-toluidinyl)-naphthalene-6-sulfonate (TNS), suggesting that the conjugate possesses the inclusion ability with biomembrane constituents such as phospholipids after transfection. These results suggest that α-CDE conjugates, particularly the G3 conjugate, could be novel nonviral gene transfer agents.