Controllable labelling of stem cells with a novel superparamagnetic iron oxide-loaded cationic nanovesicle for MR imaging.

OBJECTIVE

To investigate the feasibility of highly efficient and controllable stem cell labelling for cellular MRI.

METHODS

A new class of cationic, superparamagnetic iron oxide nanoparticle (SPION)-loaded nanovesicles was synthesised to label rat bone marrow mesenchymal stem cells without secondary transfection agents. The optimal labelling conditions and controllability were assessed, and the effect of labelling on cell viability, proliferation activity and multilineage differentiation was determined. In 18 rats, focal ischaemic cerebral injury was induced and the rats randomly injected with 1 × 10(6) cells labelled with 0-, 8- or 20-mV nanovesicles (n = 6 each). In vivo MRI was performed to follow grafted cells in contralateral striata, and results were correlated with histology.

RESULTS

Optimal cell labelling conditions involved a concentration of 3.15 μg Fe/mL nanovesicles with 20-mV positive charge and 1-h incubation time. Labelling efficiency showed linear change with an increase in the electric potentials of nanovesicles. Labelling did not affect cell viability, proliferation activity or multilineage differentiation capacity. The distribution and migration of labelled cells could be detected by MRI. Histology confirmed that grafted cells retained the label and remained viable.

CONCLUSION

Stem cells can be effectively and safely labelled with cationic, SPION-loaded nanovesicles in a controllable way for cellular MRI.

KEY POINTS

• Stem cells can be effectively labelled with cationic, SPION-loaded nanovesicles. • Labelling did not affect cell viability, proliferation or differentiation. • Cellular uptake of SPION could be controlled using cationic nanovesicles. • Labelled cells could migrate along the corpus callosum towards cerebral infarction. • The grafted, labelled cells retained the label and remained viable.