title: In vivo SPECT reporter gene imaging of regulatory T cells.
abstract: Regulatory T cells (Tregs) were identified several years ago and are key in controlling autoimmune diseases and limiting immune responses to foreign antigens, including alloantigens. In vivo imaging techniques including intravital microscopy as well as whole body imaging using bioluminescence probes have contributed to the understanding of in vivo Treg function, their mechanisms of action and target cells. Imaging of the human sodium/iodide symporter via Single Photon Emission Computed Tomography (SPECT) has been used to image various cell types in vivo. It has several advantages over the aforementioned imaging techniques including high sensitivity, it allows non-invasive whole body studies of viable cell migration and localisation of cells over time and lastly it may offer the possibility to be translated to the clinic. This study addresses whether SPECT/CT imaging can be used to visualise the migratory pattern of Tregs in vivo. Treg lines derived from CD4(+)CD25(+)FoxP3(+) cells were retrovirally transduced with a construct encoding for the human Sodium Iodide Symporter (NIS) and the fluorescent protein mCherry and stimulated with autologous DCs. NIS expressing self-specific Tregs were specifically radiolabelled in vitro with Technetium-99m pertechnetate ((99m)TcO(4)(-)) and exposure of these cells to radioactivity did not affect cell viability, phenotype or function. In addition adoptively transferred Treg-NIS cells were imaged in vivo in C57BL/6 (BL/6) mice by SPECT/CT using (99m)TcO(4)(-). After 24 hours NIS expressing Tregs were observed in the spleen and their localisation was further confirmed by organ biodistribution studies and flow cytometry analysis. The data presented here suggests that SPECT/CT imaging can be utilised in preclinical imaging studies of adoptively transferred Tregs without affecting Treg function and viability thereby allowing longitudinal studies within disease models.
authors: Medical Research Council, Centre for Transplantation, King's College London, King's Health Partners, Guy's Hospital, London, United Kingdom.
authors: Ehsan
authors: E
authors: Sharif-Paghaleh
authors: Kavitha
authors: K
authors: Sunassee
authors: Richard
authors: R
authors: Tavaré
authors: Kulachelvy
authors: K
authors: Ratnasothy
authors: Alexander
authors: A
authors: Koers
authors: Niwa
authors: N
authors: Ali
authors: Rowa
authors: R
authors: Alhabbab
authors: Philip J
authors: PJ
authors: Blower
authors: Robert I
authors: RI
authors: Lechler
authors: Lesley A
authors: LA
authors: Smyth
authors: Gregory E
authors: GE
authors: Mullen
authors: Giovanna
authors: G
authors: Lombardi
mesh_terms: D019264:Adoptive Transfer; D000818:Animals; D002460:Cell Line; D003952:Diagnostic Imaging / Q000379:methods; D017930:Genes, Reporter; D006801:Humans; D008722:Methods; D051379:Mice; D027981:Symporters / Q000235:genetics; D050378:T-Lymphocytes, Regulatory / Q000166:cytology*; D013667:Technetium; D014018:Tissue Distribution; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D014161:Transduction, Genetic; D000099209:Sodium-Iodide Symporters
chemical_list: D027981:Symporters; D013667:Technetium; D000099209:Sodium-Iodide Symporters