title: A multimodality reporter gene for monitoring transplanted stem cells.
abstract: BACKGROUND
  The aim of this study is to explore the feasibility of a triple-fused reporter gene, termed TGF [herpes simplex virus type 1 thymidine kinase (HSV1-tk), enhanced green fluorescent protein (eGFP) and firefly luciferase (Fluc)], to monitor stem cells using multimodality molecular imaging.
  
  
  METHODS
  A recombinant adenovirus vector carrying the triple-fused reporter gene (Ad5-TGF) was constructed. Bone marrow mesenchymal stem cells (BMSCs) were transfected with different virus titers of Ad5-TGF [multiplicities of infection (MOIs) were 0, 50, 100, 150, 200 and 250]. The mRNA and protein expressions of HSV1-tk, eGFP and Fluc in the transfected BMSCs were evaluated using polymerase chain reaction and Western blot. After the transfection of the BMSCs with different virus titers of Ad5-TGF (MOIs were 25, 50, 75, 100 and 125), their uptake rates of (131)I-FIAU were measured. Whole-body fluorescence, bioluminescence and micro-positron emission tomography (PET) images were acquired 1 day after the transfected BMSCs were injected into the left forelimb of rats.
  
  
  RESULTS
  After the transfection with different titers of Ad5-TGF, the positive transfection rate reached a peak (70%) when the MOI was 100. HSV1-tk, eGFP and Fluc mRNA and protein were detected in the Ad5-TGF-transfected BMSCs, which implies their successful transfection and expression. The BMSCs uptake of (131)I-FIAU increased with the adenovirus titer and incubation time and reached a plateau (approximately 5.3%) after 3 h. Strong signals were observed in the injected left forearms in the fluorescence, bioluminescence and micro-PET images.
  
  
  CONCLUSIONS
  A triple-fused reporter gene, TGF, can be used as a multifunctional molecular probe for multimodality imaging.
authors.affiliation: Department of Nuclear Medicine, Union Hospital, Tongji Medical College of Huazhong University of Science and Technology, Hubei Province Key Laboratory of Molecular Imaging, Wuhan, China.
authors.forename: Zhijun
authors.initials: Z
authors.lastname: Pei
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Lan
authors.forename: Zhen
authors.initials: Z
authors.lastname: Cheng
authors.forename: Chunxia
authors.initials: C
authors.lastname: Qin
authors.forename: Peng
authors.initials: P
authors.lastname: Wang
authors.forename: Yong
authors.initials: Y
authors.lastname: He
authors.forename: Tzu-Chen
authors.initials: TC
authors.lastname: Yen
authors.forename: Yueli
authors.initials: Y
authors.lastname: Tian
authors.forename: Fabian Pius
authors.initials: FP
authors.lastname: Mghanga
authors.forename: Yongxue
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D001086:Arabinofuranosyluracil / Q000031:analogs & derivatives / Q000378:metabolism; D001692:Biological Transport; D001854:Bone Marrow Cells / Q000166:cytology; D017930:Genes, Reporter / Q000235:genetics*; D049452:Green Fluorescent Proteins / Q000235:genetics; D018259:Herpesvirus 1, Human / Q000201:enzymology / Q000235:genetics; D049409:Luciferases, Firefly / Q000235:genetics; D045164:Mesenchymal Stem Cell Transplantation; D059630:Mesenchymal Stem Cells / Q000000981:diagnostic imaging / Q000378:metabolism*; D057054:Molecular Imaging; D011877:Radionuclide Imaging; D051381:Rats; D017207:Rats, Sprague-Dawley; D013937:Thymidine Kinase / Q000235:genetics; D014162:Transfection
chemical_list: C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D001086:Arabinofuranosyluracil; C043457:fialuridine; D049409:Luciferases, Firefly; D013937:Thymidine Kinase