Transplanted Neural Stem Cells Promote Nerve Regeneration in Acute Peripheral Nerve Traction Injury: Assessment Using MRI

OBJECTIVE. The purpose of our study was to monitor neural stem cells (NSCs) transplanted in acute peripheral nerve traction injury and to use MRI to assess the ability of NSCs to promote nerve regeneration. MATERIALS AND METHODS. After labeling with gadolinium-diethylene triamine pentaacetic acid (gadopentetate dimeglumine) and fluorescent dye (PKH26), 5 x 105 NSCs were grafted to acutely distracted sciatic nerves in 21 New Zealand White rabbits. In addition, 5 x 105 unlabeled NSCs (n = 21) and vehicle alone (n = 21) subjects were injected as a control. Serial MRI was performed with a 1.5-T scanner to determine the distribution of grafted cells. Sequential T1 and T2 values of the nerves and functional recovery were measured over a 70-day follow-up period, with histologic assessments performed at regular intervals. RESULTS. The distribution and migration of labeled NSCs could be tracked with MRI until 10 days after transplantation. Compared with vehicle control, nerves grafted with labeled or unlabeled NSCs had better functional recovery and showed improved nerve regeneration but exhibited a sustained increase of T1 and T2 values during the phase of regeneration. CONCLUSION. 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.