In vitro imaging of single living human umbilical vein endothelial cells with a clinical 3.0-T MRI scanner.

Iron oxide-labelled, single, living human umbilical vein endothelial cells (HUVECs) were imaged over time in vitro using a clinical 3.0-T magnetic resonance (MR) microscopy system. Labelling efficiency, toxicity, cell viability, proliferation and differentiation were assessed using flow cytometry, magnetic cell sorting and a phenanthroline assay. MR images were compared with normal light and fluorescence microscopy. Efficient uptake of iron oxide into HUVECs was shown, although with higher label uptake dose-dependent cytotoxic effects were observed, affecting cell viability. For MR imaging, a T2* weighted three-dimensional protocol was used with in-plane resolution of 39 x 48 microm2 and 100-microm slices with a scan time of 13 min. MRI could detect living cells in standard culture dishes at single-cell resolution, although label loss was observed that corresponded with the intracellular iron measurements. MR microscopy using iron oxide labels is a promising tool for studying HUVEC migration and cell biology in vitro and in vivo, but possible toxic effects of label uptake and loss of label over time should be taken into account.