Ultrasound-Guided Intracardial Injection and In Vivo Magnetic Resonance Imaging of Single Cells in Mice as a Paradigm for Hematogenous Metastases

Magnetic resonance imaging (MRI) has become an important technique for noninvasive cell tracking in preclinical research. Following appropriate cell labeling MRI can be used to detect larger cell cohorts and also single cells in vivo in mice. Cell distribution to different organs such as brain, liver, spleen, and kidneys can be visualized, semi-quantified, and followed over time. Thus, the fate of single tumor cells and their eventual development to solid metastases could be investigated. Mesenchymal stromal cells can be used as a paradigm for metastasizing tumor cells. We have demonstrated a strategy for magnetic and fluorescent co-labeling of mesenchymal stromal cells (MSC), ultrasound-guided intracardial cell injection with efficient systemic cell delivery, and high-resolution MRI for repetitive visualization of disseminated co-labeled MSC on a single-cell level in vivo in mice. Furthermore, the fluorescent labeling of cells enabled effective histopathological validation.