Hepatic tissue distribution of doxorubicin-loaded nanoparticles after i.v. administration in reticulosarcoma M 5076 metastasis-bearing mice.

In our previous studies, doxorubicin-loaded polyisohexylcyanoacrylate nanoparticles have been proven to increase dramatically the antitumoral activity of the cytotoxic agent in metastasis-bearing mice. The experimental model consisted of metastases induced by i.v. inoculation of reticulosarcoma M 5076 cell suspension to C57BL/6 mice. The improved efficacy of the drug was noted in terms of either metastasis count or survival. Therefore, tissue-distribution studies of this drug delivery system within the metastatic liver after i.v. administration were undertaken to gain more insight into the mechanism of action. Doxorubicin measurements in healthy hepatic or neoplastic tissue were carried out together with histological examinations using transmission electron microscopy. These results demonstrated the hepatic tissue to be an efficient reservoir of the drug when it was injected associated with nanoparticles. Accumulation of biodegradable nanoparticles with associated doxorubicin in Kupffer cells created a gradient of drug concentration for a massive and prolonged diffusion of the free drug towards the neoplastic tissue.