Distribution of polyhexyl cyanoacrylate nanoparticles in nude mice bearing human osteosarcoma.

[14C]Polyhexyl cyanoacrylate nanoparticles (PHCA), with diameters between 200 and 300 nm, were injected intravenously into nude mice bearing a human osteosarcoma. The distribution in liver, spleen, lung, heart, kidney, GI tract, gonads, brain, muscle, as well as in serum and transplanted tumor fragments was investigated by liquid scintillation counting. The peak levels in all organs with the exception of tumor and spleen were reached within 24 h. The highest levels were found in the organs of the reticuloendothelial system, liver, spleen, and lungs. The radioactivity in the other organs was found to be low, approximately 2%. In the tumor and the spleen the highest levels of radioactivity were found at approximately 7 d. At this stage the level of radioactivity in the tumor was 40 times higher than that in muscle. However, the amount of isotope detected in the tumor was still generally less than 1% of the injected dose. The concentration of radioactivity in the tumor was found to be quite variable. Higher levels of radioactivity were correlated with a low amount of tumor necrosis indicating the importance of viable tumor tissue for the accumulation of the radiolabel in this particular animal model.