Biodistribution and hepatic uptake of triplex-forming oligonucleotides against type α1(I) collagen gene promoter in normal and fibrotic rats

Fibrosis is characterized by excessive production of extracellular matrix (ECM) components, predominantly type 1 Collagen. Earlier we developed an antigene approach, using a type alpha 1(I) promoter specific TFO to inhibit Collagen gene expression. In this report, biodistribution and hepatic cellular and subcellular localization of the 25-mer antiparallel phosphorothioate triplex-forming oligonucleotide (APS TFO) were determined after intravenous injection into rats. TFOs distributed to all the major organs, with higher uptake in the liver, kidney, and spleen. The plasma concentration versus time profile of the (33)P-TFO was biphasic, with 4.36 min as t(1/2 alpha) of distribution and 34.6 min as t(1/2 beta) of elimination. TFO concentrations in the liver increased nonlinearly with increase in its dose from 0.2 to 50 mg/kg, but decreased when injected into fibrotic rats. Competition studies with polyinosinic acid (polyl) and dextran sulfate suggested the involvement of scavenger receptors in the hepatic uptake of the TFO. Intrahepatic cellular distribution by Kupffer, endothelial, and hepatic stellate cells (HSCs) accounted for almost 70% of the liver uptake of (33)P-TFO, while only 30% was associated with hepatocytes. The level of liver nuclei-associated TFO was much lower relative to that found in the cytoplasm at 2 and 4 h postinjection. TFO, however, inhibited Collagen expression as evidenced by Sirius red staining of the liver section of fibrotic rats, In conclusion, systemic delivery of the TFO against type alpha 1(I) collagen gene promoter may be used for the treatment of liver fibrosis.