Observation of the absorption of the In-DTPA-hexa-lactoside (IDHL) and its distribution in vitro by ICP-MS and TOF-SIMS

The distribution of carbohydrate drug containing indiums 'In-DTPA-hexa-lactoside (IDHL)' in human hepatoblastoma cell line (HepG2) had been observed, and cell viability was investigated at the same time. The cell survival and mitochondrial metabolism of HepG2 after treated with 50 μΜ IDHL for 24 h were investigated by 3-[4,5-dimethylthiazol-2-yl]-2,5- diphenyltetra-zolium bromide assay, and the cytotoxicity was evaluated by lactate dehydrogenase method (LDH assay). The intracellular indium ion concentration was quantitated by inductively coupled plasma mass spectrometer. Besides, the distribution of indium ion in HepG2 was also analyzed by time-of-flight secondary ion mass spectrometry for comparison. The results demonstrated that there were only small amount of indium ions distributed inside the cytoplasm and the cell membrane. This means that HepG2 had very limited IDHL absorption, and there was almost no attachment of IDHL onto the HepG2 cell membrane. In these experiments, a parsing technique was established, which can shed some light on the understanding toward the absorption and distribution of these isotope compounds in vitro.