Figure 1
From: Tracking Tumor Colonization in Xenograft Mouse Models Using Accelerator Mass Spectrometry
Workflow and validation of 14C-labeling cancer colonization assay. (A) Schematic of colonization assay workflow. Cells were first cultured with 14C-thymidine media to achieve single cell resolution and injected into NSG mice via tail vein (TV), heart (IC) or subcutaneous (SQ) routes of delivery. Injected cells were allowed to metastasize for up to 12 weeks. Tissues were harvested at early (2 weeks post injection) and late (12 weeks post injection) time points and DNA was isolated and quantified using AMS. In parallel, the activity of 14C-thymidine label in cultured cells was quantified using liquid scintillation counting (LSC). AMS measurements and LSC readings were combined to calculate the number of colonized cells per each organ examined. (B) Optimization of 14C-thymidine labeling in vitro using various concentrations of radioactivity in cell culture media (n = 3). (C) Correlation of experimental versus theoretical values of 14C-thymidine in labeled cells. (D) Pharmacokinetics of free 14C-thymidine (n = 6): mean concentration-time profile of thymidine in blood following a single intravenous administration of 700 pCi/animal in C57Bl/6 male mice. Data is expressed as the average per time point ± standard error. (E) 14C-thymidine dosing solution administered to C57Bl/6 male mice, thymidine retention time = 16 min. (F,G) HPLC chromatographs of mouse urine collected at 24 h post dose from 2 mice exposed to 14C-thymidine. Open bars indicate thymidine retention time. (H) Stability of 14C-thymidine in labeled cells transferred to non-14C-thymidine media.
