Efficient retroviral gene transfer to the liver in vivo using nonpolypeptidic mitogens

Recombinant retroviral vectors are attractive tools for achieving sustained expression of a therapeutic gene in the liver. However, cell division is r equired for efficient transduction with these vectors. Here we report that two widely used liver mitogens, triiodothyronin (T3) and cyproterone acetat e (CPA), enable hepatocyte transduction with recombinant retroviral vectors delivered in vivo into the bloodstream. Treatment with T3 as well as CPA, alone or in combination, resulted in an increase in hepatocyte replication predominantly around the portal tract. The mitogenic activity made it possi ble to transduce hepatocytes in the same location. Moreover, when administe red together, the two drugs synergized and the transduction level reached 5 % of hepatocytes. This transduction level is compatible with clinical appli cations for a number of inherited liver diseases. Since these two compounds have a long history of safe clinical use, we propose that these liver mito gens may have potential for clinical application in liver-directed gene the rapy. (C) 2001 Academic Press.