title: Efficient in vitro labeling of human neural precursor cells with superparamagnetic iron oxide particles: relevance for in vivo cell tracking.
abstract: Recent studies have raised appealing possibilities of replacing damaged or lost neural cells by transplanting in vitro-expanded neural precursor cells (NPCs) and/or their progeny. Magnetic resonance (MR) tracking of superparamagnetic iron oxide (SPIO)-labeled cells is a noninvasive technique to track transplanted cells in longitudinal studies on living animals. Murine NPCs and human mesenchymal or hematopoietic stem cells can be efficiently labeled by SPIOs. However, the validation of SPIO-based protocols to label human neural precursor cells (hNPCs) has not been extensively addressed. Here, we report the development and validation of optimized protocols using two SPIOs (Sinerem and Endorem) to label human hNPCs that display bona fide stem cell features in vitro. A careful titration of both SPIOs was required to set the conditions resulting in efficient cell labeling without impairment of cell survival, proliferation, self-renewal, and multipotency. In vivo magnetic resonance imaging (MRI) combined with histology and confocal microscopy indicated that low numbers (5 x 10(3) to 1 x 10(4)) of viable SPIO-labeled hNPCs could be efficiently detected in the short term after transplantation in the adult murine brain and could be tracked for at least 1 month in longitudinal studies. By using this approach, we also clarified the impact of donor cell death to the MR signal. This study describes a simple protocol to label NPCs of human origin using SPIOs at optimized low dosages and demonstrates the feasibility of noninvasive imaging of labeled cells after transplantation in the brain; it also evidentiates potential limitations of the technique that have to be considered, particularly in the perspective of neural cell-based clinical applications.
authors.affiliation: aStem Cell Research Institute, San Raffaele Scientific Institute, Milan, Italy.
authors.forename: Margherita
authors.initials: M
authors.lastname: Neri
authors.forename: Claudio
authors.initials: C
authors.lastname: Maderna
authors.forename: Chiara
authors.initials: C
authors.lastname: Cavazzin
authors.forename: Vivien
authors.initials: V
authors.lastname: Deidda-Vigoriti
authors.forename: Letterio S
authors.initials: LS
authors.lastname: Politi
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Scotti
authors.forename: Pasquina
authors.initials: P
authors.lastname: Marzola
authors.forename: Andrea
authors.initials: A
authors.lastname: Sbarbati
authors.forename: Angelo L
authors.initials: AL
authors.lastname: Vescovi
authors.forename: Angela
authors.initials: A
authors.lastname: Gritti
mesh_terms: D000818:Animals; D016380:Brain Tissue Transplantation; D003287:Contrast Media / Q000493:pharmacokinetics; D003911:Dextrans; D052203:Ferrosoferric Oxide; D006801:Humans; D007501:Iron / Q000493:pharmacokinetics*; D008279:Magnetic Resonance Imaging; D008280:Magnetics; D058185:Magnetite Nanoparticles; D051379:Mice; D016513:Mice, SCID; D009474:Neurons / Q000166:cytology* / Q000378:metabolism* / Q000637:transplantation; D010087:Oxides / Q000493:pharmacokinetics*; D033581:Stem Cell Transplantation; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism*; D014183:Transplantation, Heterologous
chemical_list: D003287:Contrast Media; D003911:Dextrans; D058185:Magnetite Nanoparticles; D010087:Oxides; C097921:ferumoxtran-10; D007501:Iron; C065507:ferumoxides; D052203:Ferrosoferric Oxide