In vitro assessment of Lipiodol-targeted radiotherapy for liver and colorectal cancer cell lines

Intra-arterial Lipiodol has been used to deliver targeted therapies to prim ary, and some metastatic, liver cancers. Targeted radiotherapy has been use d by substituting the iodine in Lipiodol with (131)Iodine (I-131). Early cl inical results are encouraging, but the variable response may partly depend on local pharmacokinetics. This study evaluated the in vitro cytotoxic eff ects of I-131-Lipiodol on human hepatocellular carcinoma (Hep-G2), human co lorectal metastatic cancer (SW620), human colorectal hepatic cancer (LoVo) and human umbilical vein endothelia[ cells (HUVEC) cell lines. The cell cul tures were exposed to I-131-Lipiodol for 48 h, following which cell counts and viability were assessed by haemocytometer, S-Rhodamine uptake and radio activity assay. The effect of exposure to control Lipiodol, I-131-Lipiodol and I-131 alone was evaluated. I-131-Lipiodol was cytotoxic against all the cancer cell lines but not against the non-malignant (HUVEC) cell line. The cytotoxicity effects were Very similar in all the cancer cell lines. There were no cytotoxic effects following exposure to plain I-131 in any of the cell lines (malignant and non-malignant). A similar trend was seen with rad ioactivity counts using a gamma counter. The cytotoxic effect of I-131-lipi odol had a graded effect with an increase in cytotoxicity following the inc rease in the radioactive dose. This study showed that there was a marked cy totoxic effect by I-131-Lipiodol on all the cancer cell lines. There was no difference between the controls and the (131)Iodine. This suggests that ef fective I-131-Lipiodol targeted therapy is dependent on the uptake and rete ntion of Lipiodol by malignant cells.