MR imaging could be used to help predict the degree of nerve damage and monitor the process of nerve recovery in acute peripheral nerve traction injury. (c) RSNA, 2010.

Gadopentetate dimeglumine-based labeling allowed short-term in vivo MRI tracking of NSCs grafted in injured nerves. NSCs transplantation could promote nerve regeneration in acute peripheral nerve traction injury as shown by a prolonged increase of nerve T1 and T2 values.

Purpose: To investigate in vivo MRI tracking mesenchymal stem cells (MSCs) in peripheral nerve injures using a clinically available paramagnetic contrast agent (Gd-DTPA) and commercially available rhodamine-incorporated transfection reagents (PEI-FluoR). Materials and Methods:After bone marrow MSCs were labeled with Gd-DTPA and PEI-FluoR complex, the labeling efficacy and longevity of Gd-DTPA maintenance were measured and cell viability, proliferation, and apoptosis were assessed. Thirty-six rabbits with acute sciatic nerve traction injury randomly received 1 Â 10 6 labeled (n ¼ 12) or unlabeled MSCs (n ¼ 12) or vehicle alone injection. The distribution and migration of implanted cells was followed by MRI and correlated with histology. The relative signal intensity (RSL) of the grafts was measured.Results: The labeling efficiency was 76 6 4.7% and the labeling procedure did not influence cell viability, proliferation, and apoptosis. A persistent higher RSL in grafts was found in the labeled group compared with the unlabeled and vehicle groups until 10 days after transplantation (P < 0.05). The distribution and migration of labeled cells could be tracked by MRI until 10 days after transplantation. Transplanted MSCs were not found to transdifferentiate into Schwann-like cells within 14-day follow-up.Conclusion: Labeling MSCs with the dual agents may enable cellular MRI of the engraftment in the experimental peripheral nerve injury.

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