title: Magnetodendrimers allow endosomal magnetic labeling and in vivo tracking of stem cells.
abstract: Magnetic resonance (MR) tracking of magnetically labeled stem and progenitor cells is an emerging technology, leading to an urgent need for magnetic probes that can make cells highly magnetic during their normal expansion in culture. We have developed magnetodendrimers as a versatile class of magnetic tags that can efficiently label mammalian cells, including human neural stem cells (NSCs) and mesenchymal stem cells (MSCs), through a nonspecific membrane adsorption process with subsequent intracellular (non-nuclear) localization in endosomes. The superparamagnetic iron oxide nanocomposites have been optimized to exhibit superior magnetic properties and to induce sufficient MR cell contrast at incubated doses as low as 1 microg iron/ml culture medium. When containing between 9 and 14 pg iron/cell, labeled cells exhibit an ex vivo nuclear magnetic resonance (NMR) relaxation rate (1/T2) as high as 24-39 s-1/mM iron. Labeled cells are unaffected in their viability and proliferating capacity, and labeled human NSCs differentiate normally into neurons. Furthermore, we show here that NSC-derived (and LacZ-transfected), magnetically labeled oligodendroglial progenitors can be readily detected in vivo at least as long as six weeks after transplantation, with an excellent correlation between the obtained MR contrast and staining for beta-galactosidase expression. The availability of magnetodendrimers opens up the possibility of MR tracking of a wide variety of (stem) cell transplants.
authors.affiliation: Laboratory of Diagnostic Radiology Research (CC), National Institutes of Health, Bethesda, MD 20892, USA. jwmbulte@mri.jhu.edu
authors.forename: J W
authors.initials: JW
authors.lastname: Bulte
authors.forename: T
authors.initials: T
authors.lastname: Douglas
authors.forename: B
authors.initials: B
authors.lastname: Witwer
authors.forename: S C
authors.initials: SC
authors.lastname: Zhang
authors.forename: E
authors.initials: E
authors.lastname: Strable
authors.forename: B K
authors.initials: BK
authors.lastname: Lewis
authors.forename: H
authors.initials: H
authors.lastname: Zywicke
authors.forename: B
authors.initials: B
authors.lastname: Miller
authors.forename: P
authors.initials: P
authors.lastname: van Gelderen
authors.forename: B M
authors.initials: BM
authors.lastname: Moskowitz
authors.forename: I D
authors.initials: ID
authors.lastname: Duncan
authors.forename: J A
authors.initials: JA
authors.lastname: Frank
mesh_terms: D016475:3T3 Cells; D000327:Adsorption; D000818:Animals; D001921:Brain / Q000473:pathology; D002455:Cell Division; D002460:Cell Line; D002470:Cell Survival; D011992:Endosomes / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D008280:Magnetics; D008648:Mesoderm / Q000166:cytology; D051379:Mice; D012680:Sensitivity and Specificity; D013234:Stem Cells / Q000166:cytology*; D013997:Time Factors; D014162:Transfection; D014407:Tumor Cells, Cultured; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D001616:beta-Galactosidase