title: Fluorescence molecular tomography of DiR-labeled mesenchymal stem cell implants for osteochondral defect repair in rabbit knees.
abstract: OBJECTIVE
  To assess labelling efficiency of rabbit mesenchymal stem cells (MSCs) using the near-infrared dye 1,1'-dioctadecyl-3,3,3',3'-tetramethylindotricarbocyanine iodide (DiR) and detection of labelled MSCs for osteochondral defect repair in a rabbit model using fluorescence molecular tomography-X-ray computed tomography (FMT-XCT).
  
  
  METHODS
  MSCs were isolated from New Zealand White rabbits and labelled with DiR (1.25-20 μg/mL). Viability and induction of apoptosis were assessed by XTT- and Caspase-3/-7-testing. Chondrogenic potential was evaluated by measurement of glycosaminoglycans. Labelled cells and unlabeled controls (n = 3) underwent FMT-XCT imaging before and after chondrogenic differentiation. Osteochondral defects were created surgically in rabbit knees (n = 6). Unlabeled and labelled MSCs were implanted in fibrin-clots and imaged by FMT-XCT. Statistical analyses were performed using multiple regression models.
  
  
  RESULTS
  DiR-labelling of MSCs resulted in a dose-dependent fluorescence signal on planar images in trans-illumination mode. No significant reduction in viability or induction of apoptosis was detected at concentrations below 10 μg DiR/mL (p > .05); the chondrogenic potential of MSCs was not affected (p > .05). FMT-XCT of labelled MSCs in osteochondral defects showed a significant signal of the transplant (p < .05) with additional high-resolution anatomical information about its osteochondral integration.
  
  
  CONCLUSIONS
  FMT-XCT allows for detection of stem cell implantation within osteochondral regeneration processes.
  
  
  CONCLUSIONS
  • DiR-labelling of MSCs shows no toxic side effects or impairment of chondrogenesis. • Fluorescence molecular tomography allows for detection of MSCs for osteochondral defect repair. • FMT-XCT helps to improve evaluation of cell implantation and osteochondral regeneration processes.
authors.affiliation: Department of Orthopaedic Sports Medicine, Klinikum rechts der Isar, Technische Universität München, Munich, Germany. Markus.Berninger@bgu-murnau.de.|Department of Trauma and Orthopaedic Surgery, BG Unfallklinik Murnau, Prof.-Küntscher-Strasse 8, 82418, Murnau, Germany. Markus.Berninger@bgu-murnau.de.
authors.forename: Markus T
authors.initials: MT
authors.lastname: Berninger
authors.affiliation: Institute for Biological and Medical Imaging, Technische Universität München und Helmholtz Zentrum München, Neuherberg, Germany.
authors.forename: Pouyan
authors.initials: P
authors.lastname: Mohajerani
authors.affiliation: Department of Radiology, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.
authors.forename: Melanie
authors.initials: M
authors.lastname: Kimm
authors.affiliation: Department of Orthopaedic Sports Medicine, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Masius
authors.affiliation: Institute for Biological and Medical Imaging, Technische Universität München und Helmholtz Zentrum München, Neuherberg, Germany.
authors.forename: Xiaopeng
authors.initials: X
authors.lastname: Ma
authors.affiliation: Department of Radiology, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.|Department of Clinical Radiology, Universitätsklinikum Münster, Münster, Germany.
authors.forename: Moritz
authors.initials: M
authors.lastname: Wildgruber
authors.affiliation: Institute for Medical Statistics and Epidemiology, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Haller
authors.affiliation: Institute for Experimental Oncology and Therapy Research, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.
authors.forename: Martina
authors.initials: M
authors.lastname: Anton
authors.affiliation: Department of Orthopaedic Sports Medicine, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.
authors.forename: Andreas B
authors.initials: AB
authors.lastname: Imhoff
authors.affiliation: Institute for Biological and Medical Imaging, Technische Universität München und Helmholtz Zentrum München, Neuherberg, Germany.
authors.forename: Vasilis
authors.initials: V
authors.lastname: Ntziachristos
authors.affiliation: Section of Neuroradiology, Uniklinik Köln, Cologne, Germany.|Section of Neuroradiology, Krankenhaus der Barmherzigen Brüder, Trier, Germany.
authors.forename: Tobias D
authors.initials: TD
authors.lastname: Henning
authors.affiliation: Department of Radiology, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.|Department of Diagnostic and Interventional Radiology, Universitätsklinikum Ulm, Ulm, Germany.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Meier
mesh_terms: D000818:Animals; D002232:Carbocyanines; D002454:Cell Differentiation; D002470:Cell Survival; D020219:Chondrogenesis; D005453:Fluorescence; D005456:Fluorescent Dyes; D007719:Knee Joint / Q000000981:diagnostic imaging*; D045164:Mesenchymal Stem Cell Transplantation; D059630:Mesenchymal Stem Cells; D057054:Molecular Imaging; D061848:Optical Imaging; D011817:Rabbits; D014057:Tomography, X-Ray Computed; D014945:Wound Healing
chemical_list: C574020:1,1'-dioctadecyl-3,3,3',3'-tetramethylindotricarbocyanine; D002232:Carbocyanines; D005456:Fluorescent Dyes
keywords: Cell labelling; Fluorescence molecular imaging; Mesenchymal stem cells; Osteochondral; Rabbit