RT Journal Article SR Electronic T1 In Vivo Mesenchymal Stem Cell Tracking with PET Using the Dopamine Type 2 Receptor and 18F-Fallypride JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 1342 OP 1347 DO 10.2967/jnumed.113.134775 VO 55 IS 8 A1 Veronika Schönitzer A1 Florian Haasters A1 Stefanie Käsbauer A1 Veronika Ulrich A1 Erik Mille A1 Franz Josef Gildehaus A1 Janette Carlsen A1 Manuela Pape A1 Roswitha Beck A1 Andreas Delker A1 Guido Böning A1 Wolf Mutschler A1 Wolfgang Böcker A1 Matthias Schieker A1 Peter Bartenstein YR 2014 UL http://jnm.snmjournals.org/content/55/8/1342.abstract AB Human mesenchymal stem cells (hMSCs) represent a promising treatment approach for tissue repair and regeneration. However, little is known about the underlying mechanisms and the fate of the transplanted cells. The objective of the presented work was to determine the feasibility of PET imaging and in vivo monitoring after transplantation of dopamine type 2 receptor–expressing cells. Methods: An hMSC line constitutively expressing a mutant of the dopamine type 2 receptor (D2R80A) was generated by lentiviral gene transfer. D2R80A messenger RNA expression was confirmed by reverse transcriptase-polymerase chain reaction. Localization of the transmembrane protein was analyzed by confocal fluorescence microscopy. The stem cell character of transduced hMSCs was investigated by adipogenic and osteogenic differentiation. Migration capacity was assessed by scratch assays in time-lapse imaging. In vitro specific binding of ligands was tested by fluorescence-activated cell sorting analysis and by radioligand assay using 18F-fallypride. Imaging of D2R80A overexpressing hMSC transplanted into athymic rats was performed by PET using 18F-fallypride. Results: hMSCs showed long-term overexpression of D2R80A. As expected, the fluorescence signal suggested the primary localization of the protein in the membrane of the transduced cells. hMSC and D2R80A retained their stem cell character demonstrated by their osteogenic and adipogenic differentiation capacity and their proliferation and migration behavior. For in vitro hMSCs, at least 90% expressed the D2R80A transgene and hMSC-D2R80A showed specific binding of 18F-fallypride. In vivo, a specific signal was detected at the transplantation site up to 7 d by PET. Conclusion: The mutant of the dopamine type 2 receptor (D2R80A) is a potent reporter to detect hMSCs by PET in vivo.