title: In-Vivo Detection and Tracking of T Cells in Various Organs in a Melanoma Tumor Model by 19F-Fluorine MRS/MRI.
abstract: BACKGROUND
  19F-MRI and 19F-MRS can identify specific cell types after in-vitro or in-vivo 19F-labeling. Knowledge on the potential to track in-vitro 19F-labeled immune cells in tumor models by 19F-MRI/MRS is scarce.
  
  
  OBJECTIVE
  To study 19F-based MR techniques for in-vivo tracking of adoptively transferred immune cells after in-vitro 19F-labeling, i.e. to detect and monitor their migration non-invasively in melanoma-bearing mice.
  
  
  METHODS
  Splenocytes (SP) were labeled in-vitro with a perfluorocarbon (PFC) and IV-injected into non-tumor bearing mice. In-vitro PFC-labeled ovalbumin (OVA)-specific T cells from the T cell receptor-transgenic line OT-1, activated with anti-CD3 and anti-CD28 antibodies (Tact) or OVA-peptide pulsed antigen presenting cells (TOVA-act), were injected into B16 OVA melanoma-bearing mice. The distribution of the 19F-labelled donor cells was determined in-vivo by 19F-MRI/MRS. In-vivo 19F-MRI/MRS results were confirmed by ex-vivo 19F-NMR and flow cytometry.
  
  
  RESULTS
  SP, Tact, and TOVA-act were successfully PFC-labeled in-vitro yielding 3x1011-1.4x1012 19F-atoms/cell in the 3 groups. Adoptively transferred 19F-labeled SP, TOVA-act, and Tact were detected by coil-localized 19F-MRS in the chest, abdomen, and left flank in most animals (corresponding to lungs, livers, and spleens, respectively, with highest signal-to-noise for SP vs TOVA-act and Tact, p<0.009 for both). SP and Tact were successfully imaged by 19F-MRI (n = 3; liver). These in-vivo data were confirmed by ex-vivo high-resolution 19F-NMR-spectroscopy. By flow cytometric analysis, however, TOVA-act tended to be more abundant versus SP and Tact (liver: p = 0.1313; lungs: p = 0.1073; spleen: p = 0.109). Unlike 19F-MRI/MRS, flow cytometry also identified transferred immune cells (SP, Tact, and TOVA-act) in the tumors.
  
  
  CONCLUSIONS
  SP, Tact, and TOVA-act were successfully PFC-labeled in-vitro and detected in-vivo by non-invasive 19F-MRS/MRI in liver, lung, and spleen. The portion of 19F-labeled T cells in the adoptively transferred cell populations was insufficient for 19F-MRS/MRI detection in the tumor. While OVA-peptide-activated T cells (TOVA-act) showed highest infiltration into all organs, SP were detected more reliably by 19F-MRS/MRI, most likely explained by cell division of TOVA-act after injection, which dilutes the 19F content in the T cell-infiltrated organs. Non-dividing 19F-labeled cell species appear most promising to be tracked by 19F-MRS/MRI.
authors.affiliation: Division of Cardiology, Lausanne University Hospital (CHUV), Lausanne, Switzerland.
authors.forename: Christine
authors.initials: C
authors.lastname: Gonzales
authors.affiliation: Division of Cardiology, Lausanne University Hospital (CHUV), Lausanne, Switzerland.|Institute of Physics of Biological Systems, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
authors.forename: Hikari A I
authors.initials: HA
authors.lastname: Yoshihara
authors.affiliation: Molecular Modeling Group, Swiss Institute of Bioinformatics (SIB), Lausanne, Switzerland.|Ludwig Branch for Cancer Research of the University of Lausanne, Epalinges, Switzerland.
authors.forename: Nahzli
authors.initials: N
authors.lastname: Dilek
authors.affiliation: Ludwig Branch for Cancer Research of the University of Lausanne, Epalinges, Switzerland.
authors.forename: Julie
authors.initials: J
authors.lastname: Leignadier
authors.affiliation: Ludwig Branch for Cancer Research of the University of Lausanne, Epalinges, Switzerland.
authors.forename: Melita
authors.initials: M
authors.lastname: Irving
authors.affiliation: Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), Batochime, Lausanne, Switzerland.
authors.forename: Pascal
authors.initials: P
authors.lastname: Mieville
authors.affiliation: Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), Batochime, Lausanne, Switzerland.
authors.forename: Lothar
authors.initials: L
authors.lastname: Helm
authors.affiliation: Molecular Modeling Group, Swiss Institute of Bioinformatics (SIB), Lausanne, Switzerland.|Ludwig Branch for Cancer Research of the University of Lausanne, Epalinges, Switzerland.|Department of Oncology, Lausanne University Hospital (CHUV), Lausanne, Switzerland.
authors.forename: Olivier
authors.initials: O
authors.lastname: Michielin
authors.affiliation: Division of Cardiology, Lausanne University Hospital (CHUV), Lausanne, Switzerland.|Cardiac Magnetic Resonance Center, Lausanne University Hospital (CHUV), Lausanne, Switzerland.
authors.forename: Juerg
authors.initials: J
authors.lastname: Schwitter
mesh_terms: D019264:Adoptive Transfer; D000818:Animals; D045744:Cell Line, Tumor; D058948:Cell Tracking / Q000379:methods; D066235:Fluorine-19 Magnetic Resonance Imaging / Q000379:methods*; D005466:Fluorocarbons / Q000378:metabolism*; D008099:Liver / Q000000981:diagnostic imaging / Q000276:immunology; D008168:Lung / Q000000981:diagnostic imaging / Q000276:immunology; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008546:Melanoma, Experimental / Q000000981:diagnostic imaging* / Q000276:immunology; D051379:Mice; D013154:Spleen / Q000000981:diagnostic imaging / Q000276:immunology; D013194:Staining and Labeling; D013601:T-Lymphocytes / Q000378:metabolism / Q000637:transplantation*
chemical_list: D005466:Fluorocarbons