title: Optimized labeling of bone marrow mesenchymal cells with superparamagnetic iron oxide nanoparticles and in vivo visualization by magnetic resonance imaging.
abstract: BACKGROUND
  Stem cell therapy has emerged as a promising addition to traditional treatments for a number of diseases. However, harnessing the therapeutic potential of stem cells requires an understanding of their fate in vivo. Non-invasive cell tracking can provide knowledge about mechanisms responsible for functional improvement of host tissue. Superparamagnetic iron oxide nanoparticles (SPIONs) have been used to label and visualize various cell types with magnetic resonance imaging (MRI). In this study we performed experiments designed to investigate the biological properties, including proliferation, viability and differentiation capacity of mesenchymal cells (MSCs) labeled with clinically approved SPIONs.
  
  
  RESULTS
  Rat and mouse MSCs were isolated, cultured, and incubated with dextran-covered SPIONs (ferumoxide) alone or with poly-L-lysine (PLL) or protamine chlorhydrate for 4 or 24 hrs. Labeling efficiency was evaluated by dextran immunocytochemistry and MRI. Cell proliferation and viability were evaluated in vitro with Ki67 immunocytochemistry and live/dead assays. Ferumoxide-labeled MSCs could be induced to differentiate to adipocytes, osteocytes and chondrocytes. We analyzed ferumoxide retention in MSCs with or without mitomycin C pretreatment. Approximately 95% MSCs were labeled when incubated with ferumoxide for 4 or 24 hrs in the presence of PLL or protamine, whereas labeling of MSCs incubated with ferumoxide alone was poor. Proliferative capacity was maintained in MSCs incubated with ferumoxide and PLL for 4 hrs, however, after 24 hrs it was reduced. MSCs incubated with ferumoxide and protamine were efficiently visualized by MRI; they maintained proliferation and viability for up to 7 days and remained competent to differentiate. After 21 days MSCs pretreated with mitomycin C still showed a large number of ferumoxide-labeled cells.
  
  
  CONCLUSIONS
  The efficient and long lasting uptake and retention of SPIONs by MSCs using a protocol employing ferumoxide and protamine may be applicable to patients, since both ferumoxides and protamine are approved for human use.
authors.affiliation: Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil. jasmin@biof.ufrj.br
authors.lastname: Jasmin
authors.forename: Ana Luiza M
authors.initials: AL
authors.lastname: Torres
authors.forename: Henrique M P
authors.initials: HM
authors.lastname: Nunes
authors.forename: Juliana A
authors.initials: JA
authors.lastname: Passipieri
authors.forename: Linda A
authors.initials: LA
authors.lastname: Jelicks
authors.forename: Emerson L
authors.initials: EL
authors.lastname: Gasparetto
authors.forename: David C
authors.initials: DC
authors.lastname: Spray
authors.forename: Antonio C
authors.initials: AC
authors.lastname: Campos de Carvalho
authors.forename: Rosalia
authors.initials: R
authors.lastname: Mendez-Otero
mesh_terms: D017667:Adipocytes / Q000187:drug effects; D000818:Animals; D001853:Bone Marrow / Q000187:drug effects*; D002454:Cell Differentiation / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D019902:Chondrocytes / Q000187:drug effects; D007501:Iron / Q000008:administration & dosage*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D058185:Magnetite Nanoparticles / Q000008:administration & dosage*; D008297:Male; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000187:drug effects*; D051379:Mice; D008810:Mice, Inbred C57BL; D016685:Mitomycin / Q000008:administration & dosage; D010011:Osteocytes / Q000187:drug effects; D010087:Oxides / Q000008:administration & dosage*; D011107:Polylysine / Q000008:administration & dosage; D011479:Protamines / Q000008:administration & dosage; D051381:Rats; D017208:Rats, Wistar; D013194:Staining and Labeling / Q000379:methods*
chemical_list: D058185:Magnetite Nanoparticles; D010087:Oxides; D011479:Protamines; C094094:carboxydextran-coated magnetic iron oxide particles; D011107:Polylysine; D016685:Mitomycin; D007501:Iron