Liver fibrosis is characterized by abnormal accumulation of extracellular matrix (ECM), namely, fibrillar collagens in the hepatic stellate cells (HSCs). Earlier, we developed an antigene approach, using a type α1(I) collagen gene promoter specific triplex-forming oligonucleotide (TFO) to inhibit collagen gene expression. In this paper, to enhance overall delivery of TFOs to the liver and more specifically to HSCs, we synthesized man nose 6-phosphate-bovine serum albumin (M6P-BSA) by phosphorylating p-nitrophenyl-α-D- mannopyranoside, reducing its nitro group, and reacting it with thiophosgene to produce p-isothiocyanatophenyl-6-phospho-α-D-mannopyranoside (itcM6P) for conjugation with BSA. 33P-TFO was conjugated with M6P-BSA via a disulfide bond, and the stability of the (M6P)20-BSA-TFO conjugate was determined. Following tail vein injection into rats, (M6P) 20-BSA-33P-TFO rapidly cleared from the circulation and accumulated mainly in the liver. Almost 66% of the injected (M6P) 20-BSA33P-TFO accumulated in the liver at 30 min postinjection, which was significantly higher than that deposited after injection of 33P-TFO. A large proportion of the injected (M6P) 20-BSA-33P-TFO was taken up by the HSCs as evidenced by determination of radioactivity in the digested liver cells upon liver perfusion and separation on a Nycodenz gradient. Therefore, this TFO conjugate may be used for the treatment of liver fibrosis.
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