To probe the possibility of in vivo tracking stem cells implanted in rabbit spinal cords with radionuclide imaging

3×106 human neural progenitor cells (hNPC-TERT) were implanted in rabbit spinal cord. D2 receptor expression of the cells before or after transplantation was quantitatively and qualitatively analyzed with radioligand receptors assay and immunofluorescence respectively. At 20 min after injection of 11C-raclopride

rabbits received PET scan or were sacrificed and spinal cords removed and received PET scan. D2 receptor expression of hNPC-TERT cells was proved by immunofluorescence. Radioligand receptors assay showed that hNPC-TERT cell highly expressed D2 receptor (Bmax=8×104) with high affinity to raclopride (Kd=1.518 nmol/L). PET (Positron Emission Tomography) scans on animals showed visible accumulations of radioactivity at hNPC-TERT cell transplantation sites but not at HeLa cell transplantation sites. The ROI analysis showed a statistical difference between the maximal standard uptake value on transplantation sites of the two groups. The result was further proved by the ex vivo PET imaging of spinal cord. The success in displaying the implanted cells in spinal cord provides the feasibility of in vivo tracking of stem cells after transplantation with radionuclide imaging.