Labeling protocols for in vivo tracking of human skeletal muscle cells (HSkMCs) by magnetic resonance and bioluminescence imaging.

Purpose: We propose herein labeling protocols for multimodal in vivo visualization of human skeletal muscle cells (HSkMCs) by MRI and BLI to investigate the survival, localization, and proliferation/differentiation of these cells in cell-mediated therapy.

Procedures: HSkMCs were labeled with different quantities of Endorem® and transfection agents or infected with lentiviral vector expressing the luciferase gene under the myogenin promoter. Cells were evaluated before and after intra-arterial injection in NUDE mice with N₂-induced muscle inflammation.

Results: Neither iron labeling nor infection affected cell features; the number of iron-positive cells increased proportionally to the iron content in the medium and in the presence of transfection agents. Loaded cells were detected for up to 1 month by MRI and 2 months by BLI.

Conclusions: These protocols could be used to visualize new stem cells, in vivo and over time, in preclinical studies of cell-based treatments for myopathies of different etiologies.