Receptor mediated uptake of a radiolabeled contrast agent sensitive to beta-galactosidase activity

Radiolabeling of the MRI contrast agent 1-[2-(beta-galactopyranosyloxy)propyl]-4,7,10-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecane with (111)In, and its evaluation is reported. Radiolabeling was performed in acetate buffer with 50-78% radiochemical yield. In vitro studies revealed that the asialoglycoprotein receptor-poor cell line MH1C1 has low uptake, while the receptor-rich cell lines BNL-CL2 and Hep G2 have higher uptake. In vivo, the uptake of the compound in receptor-rich organ liver was very high. Blocking the receptor in vivo, reduced liver uptake by 90% suggesting that the compound localizes in receptor-enriched tissues by binding to the asialoglycoprotein receptor.