Imaging and therapy of liver fibrosis using bioreducible polyethylenimine/siRNA complexes conjugated with N-acetylglucosamine as a targeting moiety

Diagnosis and therapy of early stage liver fibrosis is very important for the treatment of fatal liver diseases. Here, we report on the targeted imaging and therapy of activated hepatic stellate cells (HSCs) and fibrotic liver tissue using N-acetylglucosamine (GlcNAc)- and indocyanine green (ICG)-conjugated PEI/siRNA complexes. The conjugation of a disulfide bond to PEI (PEI-D) was achieved by Michael addition. We modified PEI with N-acetylglucosamine (PEI-D-GlcNAc), which can specifically interact with desmin on activated HSCs, using the EDC coupling method. Confocal microscopic analysis showed that the PEI-D-GlcNAc/siRNA was internalized by HSCs upon interaction with surface desmin. In vitro western blot analysis confirmed that PEI-D-GlcNAc provided strong protein knock-down after transfection with TGFβ1siRNA into HSCs. After a tail vein injection of ICG-conjugated complexes, the PEI-D-GlcNAc-ICG/siRNA complex accumulated to a greater extent in the livers of fibrotic mice than in normal mice over an extended duration. Moreover, immunohistofluorescence analysis confirmed that the PEI-D-GlcNAc-ICG/siRNA complex specifically colocalized with HSCs, which are desmin-positive cells, in fibrotic liver tissues. In vivo TGFβ1siRNA delivery also resulted in superior protein knock-down when using the PEI-D-GlcNAc complex. These results demonstrate that the PEI-D-GlcNAc-ICG/TGFβ1siRNA complex is a useful tool for imaging and treatment of liver fibrosis.