Target specific systemic delivery of TGF-β siRNA/(PEI-SS)-g-HA complex for the treatment of liver cirrhosis

A target specific systemic delivery system of siRNA therapeutics was successfully developed using reducible polyethyleneimine grafted hyaluronic acid [(PEI-SS)-g-HA] conjugates. The PEI-SS was synthesized by Michael addition of low molecular weight PEI (MW = 2000) with cystaminebisacrylamide (CBA), and grafted to carboxyl groups of HA via amide bond formation after activation with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and 1-hydroxybenzotriazole monohydrate (HOBt). The confocal microscopic and fluorometric analyses confirmed the effective cellular uptake of siRNA/(PEI-SS)-g-HA complex by HA receptor mediated endocytosis. In vitro gene silencing efficiency was ca. 80% in the presence of 10 vol% serum and ca. 50% in the presence of 50 vol% serum in B16F1 melanoma cells and activated hepatic stellate cells (HSCs). Furthermore, target specific systemic delivery of apolipoprotein B (ApoB) siRNA/(PEI-SS)-g-HA complex resulted in a drastically reduced ApoB mRNA level down to ca. 20% in a dose-dependent manner. Finally, TGF-β siRNA/(PEI-SS)-g-HA complex showed a feasible therapeutic effect on liver cirrhosis with a significantly reduced nodule formation, collagen content, and HSC number. The siRNA/(PEI-SS)-g-HA complex can be exploited for the target specific systemic treatment of various liver diseases.