Positive MRI Enhancement in THP-1 Cells with Gd 2 O 3 Nanoparticles

There is a demand for more efficient and tissue-specific MRI contrast agents and recent developments involve the design of substances useful as molecular markers and magnetic tracers. In this study, nanoparticles of gadolinium oxide (Gd 2 O 3 ) have been investigated for cell labeling and capacity to generate a positive contrast. THP-1, a monocytic cell line that is phagocytic, was used and results were compared with relaxivity of particles in cell culture medium (RPMI 1640). The results showed that Gd 2 O 3 -labeled cells have shorter T 1 and T 2 relaxation times compared with untreated cells. A prominent difference in signal intensity was observed, indicating that Gd 2 O 3 nanoparticles can be used as a positive contrast agent for cell labeling. The r 1 for cell samples was 4.1 and 3.6 s -1 m m -1 for cell culture medium. The r 2 was 17.4 and 12.9 s -1 m m -1 , respectively. For r 1 , there was no significant difference in relaxivity between particles in cells compared to particles in cell culture medium, ( p r 1 = 0.36), but r 2 was significantly different for the two different series ( p r 2 = 0.02). Viability results indicate that THP-1 cells endure treatment with Gd 2 O 3 nanoparticles for an extended period of time and it is therefore concluded that results in this study are based on viable cells.