Gadofluorine is a novel macrocyclic, amphiphilic
gadolinium-based
contrast agent. We found that
malignant glioma cells could be labeled in vitro using
Gadofluorine without the need for transfection agents or any other additional means. Labeling with
Gadofluorine enhanced the visualization of
glioma cells in T(1)-weighted sequences, even if the cells had been cultured in medium without
Gadofluorine over several days. The intracellular uptake of
Gadofluorine was measured and the loss of relevant amounts of
Gadofluorine into the cell culture medium was ruled out by MRI. Confocal
laser fluorescence microscopy revealed Cy-5-labeled
Gadofluorine in the perinuclear cytoplasmic region, but neither within the nucleus nor bound to the cell membrane. Adverse effects of cellular
Gadofluorine uptake were ruled out by proliferation and migration assays. Finally, in vivo analyses provided good visibility of labeled
glioma cells in T(1)-weighted sequences after intracerebral injection in mice for more than 2 weeks. We thus conclude that
Gadofluorine can easily be used to label
glioma cells in vitro without affecting
glioma cell biology.
Gadofluorine provides an interesting alternative for cellular labeling if
iron oxide particles are incorporated insufficiently by target cells or if the vicinity of susceptibility artifacts prohibits the use of signal-decreasing
contrast agents.