title: Cellular magnetic resonance imaging contrast generated by the ferritin heavy chain genetic reporter under the control of a Tet-On switch.
abstract: BACKGROUND
  Despite the strong appeal of ferritin as a magnetic resonance imaging (MRI) reporter for stem cell research, no attempts have been made to apply this genetic imaging reporter in stem cells in an inducible manner, which is important for minimizing the potential risk related to the constitutive expression of an imaging reporter. The aim of the present study was to develop an inducible genetic MRI reporter system that enables the production of intracellular MRI contrast as needed.
  
  
  METHODS
  Ferritin heavy chain (FTH1) was genetically modified by adding a Tet-On switch. A C3H10T1/2 cell line carrying Tet-FTH1 (C3H10T1/2-FTH1) was established via lentiviral transduction. The dose- and time-dependent expression of FTH1 in C3H10T1/2 cells was assessed by western blot and immunofluorescence staining. The induced "ON" and non-induced "OFF" expressions of FTH1 were detected using a 3.0 T MRI scanner. Iron accumulation in cells was analyzed by Prussian blue staining and transmission electron microscopy (TEM).
  
  
  RESULTS
  The expression of FTH1 was both dose- and time-dependently induced, and FTH1 expression peaked in response to induction with doxycycline (Dox) at 0.2 μg/ml for 72 h. The induced expression of FTH1 resulted in a significant increase in the transverse relaxation rate of C3H10T1/2-FTH1 cells following iron supplementation. Prussian blue staining and TEM revealed extensive iron accumulation in C3H10T1/2-FTH1 cells in the presence of Dox.
  
  
  CONCLUSIONS
  Cellular MRI contrast can be produced as needed via the expression of FTH1 under the control of a Tet-On switch. This finding could lay the groundwork for the use of FTH1 to track stem cells in vivo in an inducible manner.
authors.affiliation: Department of Radiology, Children's Hospital of Chongqing Medical University, 136 Zhongshan 2 Road, Yuzhong District, Chongqing, 400014, China. 570792952@qq.com.|Ministry of Education Key Laboratory of Child Development and Disorders, 136 Zhongshan 2 Road, Yuzhong District, Chongqing, 400014, China. 570792952@qq.com.|Key Laboratory of Pediatrics in Chongqing, 136 Zhongshan 2 Road, Yuzhong District, Chongqing, 400014, China. 570792952@qq.com.|Chongqing International Science and Technology Cooperation Center For Child Development and Disorders, 136 Zhongshan 2 Road, Yuzhong District, Chongqing, 400014, China. 570792952@qq.com.
authors.forename: Xiaoya
authors.initials: X
authors.lastname: He
authors.affiliation: Department of Radiology, Children's Hospital of Chongqing Medical University, 136 Zhongshan 2 Road, Yuzhong District, Chongqing, 400014, China. cai_jinhua@126.com.|Ministry of Education Key Laboratory of Child Development and Disorders, 136 Zhongshan 2 Road, Yuzhong District, Chongqing, 400014, China. cai_jinhua@126.com.|Key Laboratory of Pediatrics in Chongqing, 136 Zhongshan 2 Road, Yuzhong District, Chongqing, 400014, China. cai_jinhua@126.com.|Chongqing International Science and Technology Cooperation Center For Child Development and Disorders, 136 Zhongshan 2 Road, Yuzhong District, Chongqing, 400014, China. cai_jinhua@126.com.
authors.forename: Jinhua
authors.initials: J
authors.lastname: Cai
authors.affiliation: Department of Radiology, Children's Hospital of Chongqing Medical University, 136 Zhongshan 2 Road, Yuzhong District, Chongqing, 400014, China. 2673662485@qq.com.|Ministry of Education Key Laboratory of Child Development and Disorders, 136 Zhongshan 2 Road, Yuzhong District, Chongqing, 400014, China. 2673662485@qq.com.|Key Laboratory of Pediatrics in Chongqing, 136 Zhongshan 2 Road, Yuzhong District, Chongqing, 400014, China. 2673662485@qq.com.|Chongqing International Science and Technology Cooperation Center For Child Development and Disorders, 136 Zhongshan 2 Road, Yuzhong District, Chongqing, 400014, China. 2673662485@qq.com.
authors.forename: Bo
authors.initials: B
authors.lastname: Liu
authors.affiliation: Department of Radiology, Children's Hospital of Chongqing Medical University, 136 Zhongshan 2 Road, Yuzhong District, Chongqing, 400014, China. 582604807@qq.com.|Ministry of Education Key Laboratory of Child Development and Disorders, 136 Zhongshan 2 Road, Yuzhong District, Chongqing, 400014, China. 582604807@qq.com.|Key Laboratory of Pediatrics in Chongqing, 136 Zhongshan 2 Road, Yuzhong District, Chongqing, 400014, China. 582604807@qq.com.|Chongqing International Science and Technology Cooperation Center For Child Development and Disorders, 136 Zhongshan 2 Road, Yuzhong District, Chongqing, 400014, China. 582604807@qq.com.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhong
authors.affiliation: Department of Radiology, Children's Hospital of Chongqing Medical University, 136 Zhongshan 2 Road, Yuzhong District, Chongqing, 400014, China. 308787364@qq.com.|Ministry of Education Key Laboratory of Child Development and Disorders, 136 Zhongshan 2 Road, Yuzhong District, Chongqing, 400014, China. 308787364@qq.com.|Key Laboratory of Pediatrics in Chongqing, 136 Zhongshan 2 Road, Yuzhong District, Chongqing, 400014, China. 308787364@qq.com.|Chongqing International Science and Technology Cooperation Center For Child Development and Disorders, 136 Zhongshan 2 Road, Yuzhong District, Chongqing, 400014, China. 308787364@qq.com.
authors.forename: Yong
authors.initials: Y
authors.lastname: Qin
mesh_terms: D000818:Animals; D002460:Cell Line; D049109:Cell Proliferation; D058948:Cell Tracking; D003287:Contrast Media / Q000378:metabolism; D004318:Doxycycline / Q000494:pharmacology; D005293:Ferritins / Q000096:biosynthesis* / Q000235:genetics; D017930:Genes, Reporter; D007501:Iron / Q000378:metabolism; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008809:Mice, Inbred C3H; D010088:Oxidoreductases; D015533:Transcriptional Activation / Q000187:drug effects
chemical_list: D003287:Contrast Media; D005293:Ferritins; D007501:Iron; C454461:FTH1 protein, human; D010088:Oxidoreductases; D004318:Doxycycline