title: In vivo detection limits of magnetically labeled embryonic stem cells in the rat brain using high-field (17.6 T) magnetic resonance imaging.
abstract: Stem cell transplantation is a promising therapeutic approach for several neurological disorders. However, it has yet to fulfill its high expectations, partially due to the lack of a reliable noninvasive method for monitoring the biodistribution of the grafted stem cells in vivo. We have used high-resolution magnetic resonance imaging (MRI) at 17.6 T, combined with efficient magnetic labeling of the stem cells with iron oxide nanoparticles, in order to assess the in vivo detection limit in small animal models. Injection of different concentrations of magnetically labeled stem cells in gel phantoms led to significant reductions in image intensity from small cellular clusters of less than 10 cells. To determine the detection limit in vivo, various numbers of both labeled and unlabeled cells were injected stereotactically into the striatum of rats. Significant hypointense signal changes were observed for 100 labeled cells. After injection of approximately 20 labeled cells, signal reduction at the injection site was observed but could not be assigned unambiguously to the cells. Our results show that high-field MRI allows tracking of a minimal number of cells in vivo, well below the number used in previous studies, opening the possibility of gaining new insights into cell migration and differentiation.
authors.affiliation: Department of Radiology and Neuroradiology, Charité University Hospital, Berlin, Germany. albrecht.stroh@charite.de
authors.forename: Albrecht
authors.initials: A
authors.lastname: Stroh
authors.forename: Cornelius
authors.initials: C
authors.lastname: Faber
authors.forename: Thomas
authors.initials: T
authors.lastname: Neuberger
authors.forename: Peer
authors.initials: P
authors.lastname: Lorenz
authors.forename: Katharina
authors.initials: K
authors.lastname: Sieland
authors.forename: Peter M
authors.initials: PM
authors.lastname: Jakob
authors.forename: Andrew
authors.initials: A
authors.lastname: Webb
authors.forename: Herbert
authors.initials: H
authors.lastname: Pilgrimm
authors.forename: Ralf
authors.initials: R
authors.lastname: Schober
authors.forename: Elena E
authors.initials: EE
authors.lastname: Pohl
authors.forename: Claus
authors.initials: C
authors.lastname: Zimmer
mesh_terms: D000818:Animals; D001921:Brain / Q000166:cytology*; D002452:Cell Count; D002454:Cell Differentiation / Q000502:physiology; D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured; D005290:Ferric Compounds; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008280:Magnetics; D051379:Mice; D018613:Microscopy, Confocal; D008863:Microspheres; D008953:Models, Anatomic; D017072:Neostriatum / Q000166:cytology; D051381:Rats; D013054:Spectrophotometry, Atomic; D033581:Stem Cell Transplantation / Q000379:methods*; D013234:Stem Cells / Q000502:physiology*; D013238:Stereotaxic Techniques
chemical_list: D005290:Ferric Compounds; C000499:ferric oxide