title: [Transferrin receptor expression of human mesenchymal stem cells and in vitro tracking by autoradiography after transplantation in spinal cord].
abstract: OBJECTIVE
  To determine transferrin receptor (TfR) expression of human mesenchymal stem cells (MSCs) in vitro and after transplantation in rabbit spinal cord,and to detect implanted MSCs by in vitro autoradiography.
  
  
  METHODS
  Human mesenchymal stem cells (hMSCs) were isolated from fetal blood. Flow cytometry assay, immuno-fluorescent staining and receptor binding assay were used to determine TfR expression of hMSCs. Radioiodinated transferrin saturated with iron [(125)I-Tf(Fe)(2)] was used as tracer. The hMSCs transplanted in rabbit spinal cord was tracked by in vitro autoradiography. Diffusion of (125)I-Tf(Fe)(2) in spinal cord was examined with autoradiography.
  
  
  RESULTS
  TfR expression of MSCs was demonstrated by flow cytometry assay, immuno-fluorescent staining and receptor binding assay in vitro. (125)I-Tf(Fe)(2) bound to hMSCs with a equilibrium dissociation constant (KD) of (0.98+/-0.12) nmol/L and a maximal density of binding sites (B(max)) of (107 702+/-6 226) sites per cell. Immuno-fluorescent staining showed that TfRs were expressed on hMSCs on the 2nd day but not be expressed on the 10th day post transplantation. Autoradiography showed distinct accumulation of (125)I-Tf(Fe)(2) but not (125)I-HSA at hMSCs implantation sites of spinal cord sections on the 2nd day post transplantation. (125)I-Tf(Fe)(2) had diffused into spinal cord 16 hours after incubation.
  
  
  CONCLUSIONS
  Implanted hMSCs could be detected by in vitro autoradiography with (125)I-Tf(Fe)(2) on the 2nd day after being transplanted in spinal cord. To track implanted hMSCs with radionuclide imaging techniques in vivo, TfR was a suitable target for imaging and radioiodinated Tf(Fe)(2) was a feasible tracer.
authors.affiliation: Department of Orthopedics, Peking University Third Hospital, Beijing 100083, China.
authors.forename: Jin-zhu
authors.initials: JZ
authors.lastname: Bai
authors.forename: Wei-min
authors.initials: WM
authors.lastname: Ding
authors.forename: Zhong-jun
authors.initials: ZJ
authors.lastname: Liu
authors.forename: Min-jun
authors.initials: MJ
authors.lastname: Yu
authors.forename: Jia-he
authors.initials: JH
authors.lastname: Tian
authors.forename: Fan
authors.initials: F
authors.lastname: Wang
authors.forename: Jin
authors.initials: J
authors.lastname: Du
authors.forename: Xiao-yan
authors.initials: XY
authors.lastname: Zhang
authors.forename: Ling-song
authors.initials: LS
authors.lastname: Li
authors.forename: Li
authors.initials: L
authors.lastname: Shen
mesh_terms: D000818:Animals; D001345:Autoradiography; D002454:Cell Differentiation; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes; D045164:Mesenchymal Stem Cell Transplantation; D059630:Mesenchymal Stem Cells / Q000737:chemistry*; D011817:Rabbits; D011990:Receptors, Transferrin / Q000032:analysis*
chemical_list: D007457:Iodine Radioisotopes; D011990:Receptors, Transferrin