Novel bimodal iron oxide particles for efficient tracking of human neural stem cells in vivo

Aims: We validated novel bimodal iron oxide particles as substitute of ferumoxides for efficient labeling of human neural stem cells (NSCs). The dextrane-coated FeraTrack Direct (FTD)-Vio particles have additional far-red fluorophores for microscopic cell analysis. Methods: MR relaxometry, spectrophotometric iron determination and microscopy are used for characterization in vitro and in vivo. Results: Efficient uptake is not transfection agent-dependent. FTD-Vio594 labeling had no influence on viability, proliferation, migration and differentiation capacity. It allows MRI-based tracking of engrafted NSCs in mouse brain up to 11 days, complemented by bioluminescence imaging of firefly luciferase expressed by the engrafted cells. Conclusion: Our results highlight the FTD-Vio594 particles as safe and sensitive substitute of ferumoxides for longitudinal tracking of NSCs in preclinical studies.