N1,N12-Diacyl spermines: SAR studies on non-viral lipopolyamine vectors for plasmid DNA and siRNA formulation

To study the efficiency of novel synthetic N(1),N(12)-diacyl spermines on DNA and siRNA binding, and to compare their transfection efficiency with viability in cell lines.

Five long chain N(1),N(12)-diacyl lipopolyamines: N(1),N(12)-[didecanoyl, dimyristoyl, dimyristoleoyl, distearoyl and dioleoyl]-1,12-diamino-4,9-diazadodecane were synthesized from the naturally occurring polyamine spermine. Their abilities to condense DNA and to form nanoparticles were characterized. Transfection efficiencies were studied in FEK4 primary skin cells and in an immortalized cancer cell line (HtTA), and compared with N(4),N(9)-regioisomers. Also, the abilities of these novel compounds to bind to siRNA-forming nanoparticles were studied using a RiboGreen intercalation assay, and their abilities to deliver fluorescein-tagged siRNA into cells were quantified and compared with TransIT-TKO.

By incorporating two long aliphatic chains and varying their acylation position, length, and oxidation state in a stepwise manner, we show efficient p and siRNA formulation and delivery to primary skin and cancer cell lines. Although two C14 chains (both saturated or both mono-cis-unsaturated) were efficient transfecting agents, they were highly toxic.

N(1),N(12)-Dioleoyl spermine efficiently binds to and delivers pDNA and siRNA with high cell viability even in a primary skin cell line. It is a novel, efficient non-viral vector in the presence of serum.