Targeted gene delivery to sinusoidal endothelial cells: DNA nanoassociate bearing hyaluronan-glycocalyx

Liver sinusoidal endothelial cells (SECs) possess unique receptors that recognize and internalize hyaluronic acid (HA). To develop a system for targeting foreign DNA to SECs, comb-type polycations having HA side chains were prepared by coupling HA to poly(L-lysine) (PLL). The HA-grafted-PLL copolymer (PLL-g-HA) thus formed was mixed with DNA in 154 mM NaCl to form soluble nanoassociates bearing hydrated hyaluronate shells. Agarose gel retardation assays revealed selective interaction of the PLL backbone with DNA despite the presence of polyanionic HA side chains. To determine whether the PLL-g-HA/DNA complexes were recognized by SEC HA receptors in vivo, we injected Wistar rats i.v. via the tail vein with PLL-g-HA complexed to a beta-galactosidase expression plasmid (pSV beta-Gal) labeled with 32P. One hour postinjection, >90% of the injected radioactivity remained in the liver. Administration of the PLL-g-HA complexed to an FITC-labeled DNA revealed that the carrier-DNA complex was distributed exclusively in SECs. A large number of SECs expressing beta-galactosidase was detected along the sinusoidal lining after transfection with PLL-g-HA/pSV beta-Gal. Moreover, PLL-g-HA effectively stabilized DNA triplex formation. In conclusion, the new PLL-g-HA/DNA carrier system permits targeted transfer of exogenous genes selectively to the SECs.