Magnetic resonance tracking of transplanted stem cells in rat brain and spinal cord.

BACKGROUND

Magnetic resonance imaging provides a noninvasive method to study the fate of transplanted cells in vivo.

OBJECTIVE

We studied the fate of embryonic and mesenchymal stem cells labeled with iron oxide nanoparticles (Endorem) and human CD34+ cells labeled with magnetic MicroBeads (Miltenyi) in rats with a cortical or spinal cord lesion.

METHODS

Cells were grafted intracerebrally, contralaterally to a cortical photochemical lesion, or injected intravenously.

RESULTS

During the 1st week after transplantation, transplanted cells migrated to the lesion and were visible in the lesion on MR images as a hypointensive signal, persisting for more than 30 days. In rats with a balloon-induced spinal cord compression lesion, we observed an increase in functional recovery and hind limb sensitivity after implantation of Endorem-labeled mesenchymal stem cells or a freshly prepared mononuclear fraction of bone marrow cells or after injection of granulocyte colony-stimulating factor. Morphometric measurements in the center of the lesions showed an increase in white matter volume in cell-treated animals. Prussian blue staining confirmed a large number of Prussian blue-positive cells, and the lesions were considerably smaller than in control animals.

CONCLUSIONS

These studies demonstrate that magnetic resonance imaging of grafted adult as well as embryonic stem cells labeled with iron oxide nanoparticles is a useful method for evaluating their migration and fate in CNS.