Effects of MRI contrast agents on human embryonic lung fibroblasts.

RATIONALE AND
OBJECTIVES: The objective of this investigation was to evaluate 6 magnetic resonance contrast media (CM) with regard to their different effects on human embryonic lung fibroblasts (HEL-299).
METHODS: Human embryonic fibroblasts (HEL-299) were incubated with 1x, 5x, 10x, and 20x of the normal molar blood concentration (1x, 5x, 10x, 20x conc.) reached through routine contrast media applications for MRI examinations. Four gadolinium-based CM, ie, Gadovist, Magnevist, Multihance, Omniscan, Teslascan (Manganese-based), and Resovist (Iron-based), with incubation periods over 4 hours and 24 hours were investigated. Proliferation kinetics, colony formation, and viability assays were performed after 4 and 24 hours of treatment. Apoptotic cells were quantified after tetramethylrhodamine ethyl ester staining following 24 hours of CM media incubation (20x conc.) by fluorescence activated cell sorting cytometry. Furthermore, immunofluorescence images with vimentin staining were obtained (20x conc., 24 hours treatment). Cell cycle analysis was performed after 24 hours of incubation and 20x conc. directly after incubation and 24 hours later (fluorescence activated cell sorting cytometry).
RESULTS: The proliferation kinetics performed with 20x conc. revealed a persistent increase in cell numbers until day 11 for all CM without significant differences after 4 hours of incubation. A significant reduction in initial cell numbers was recorded in the 24-hours-group after 4 days of CM incubation with Magnevist, Multihance, Omniscan, and Teslascan. Solely cells incubated with Resovist and Gadovist failed to show decreased cell numbers when compared with the control group. However, a considerable cell regain occurred afterward reaching control-group levels on day 21. Colony numbers were significantly reduced (about 20%, respectively) with Magnevist at 10x and 20x conc., as well as Omniscan and Multihance at 20x conc. when compared with all other groups, P < 0.05. Cell-cycle distribution showed a reduction of S-phase cells for Magnevist, Omniscan, and Multihance (2.9%-10.5%) when compared with Gadovist, Resovist and Teslascan (16.7%-21.0%). Twenty-four hours after incubation, the percentiles of cells in S-phase were significantly increased for Magnevist, Omniscan, and Multihance (31.4%-38.5%) when compared with Gadovist, Resovist, and Teslascan (18.6%-26.8%), P < 0.05. Viability was not impaired by administration of any CM and no apoptosis was seen after tetramethylrhodamine ethyl ester staining at 24 hours of incubation. Cell morphology remained unchanged in vimentin-staining for all CM and conditioning regimens.
CONCLUSIONS: No toxic effects on embryonic fetal lung fibroblasts were detectable after 4 and 24 hours of incubation in 6 MRI CM and 10x to 20x conc. in our setting. Antiproliferative effects, initially detected with Magnevist, Omniscan and Multihance, were rapidly compensated for.