title: Magnetic resonance contrast and biological effects of intracellular superparamagnetic iron oxides on human mesenchymal stem cells with long-term culture and hypoxic exposure.
abstract: OBJECTIVE
  Human mesenchymal stem cells (hMSCs) have gained interest for treatment of stroke injury. Using in vitro culture, the purpose of this study was to investigate the long-term detectability of hMSCs by magnetic resonance imaging (MRI) after transfection with a superparamagnetic iron oxide (SPIO) and evaluate the effects of SPIO on cellular activity, particularly under an ischemic environment.
  
  
  METHODS
  hMSCs were exposed to low doses of SPIOs. After a short incubation period, cells were cultured for additional 1, 7 and 14 d to evaluate proliferation, colony formation and multilinear potential. Labeled cells were imaged and evaluated in agarose to quantify R2 and R2∗ contrast at each time point. Cells were placed in a low-oxygen, low-serum environment and tested for cytotoxicity. In addition, labeled cells were transplanted into an ischemic stroke model and evaluated with ex vivo MRI and histology.
  
  
  RESULTS
  Cellular events such as proliferation and differentiation were not affected at any of the exposures tested when cultured for 14 d. The low iron exposure and short incubation time are sufficient for detectability with MRI. However, the higher iron dosage results in higher calcification and cytotoxicity under in vitro ischemic conditions. Transplantation of the hMSCs labeled with an initial exposure of 22.4 μg of Fe showed excellent retention of contrast in stroke-induced rats.
  
  
  CONCLUSIONS
  Although SPIO labeling is stable for long-term MRI detection and has limited effects on the multilineage potential of hMSCs, high-dose SPIO labeling may affect hMSC survival under serum and oxygen withdrawal.
authors.affiliation: Chemical & Biomedical Engineering, FAMU-FSU College of Engineering, The Florida State University, Tallahassee, Florida, USA.
authors.forename: Jens T
authors.initials: JT
authors.lastname: Rosenberg
authors.forename: Katelyn L
authors.initials: KL
authors.lastname: Sellgren
authors.forename: Afi
authors.initials: A
authors.lastname: Sachi-Kocher
authors.forename: Fabian
authors.initials: F
authors.lastname: Calixto Bejarano
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Baird
authors.forename: Michael W
authors.initials: MW
authors.lastname: Davidson
authors.forename: Teng
authors.initials: T
authors.lastname: Ma
authors.forename: Samuel C
authors.initials: SC
authors.lastname: Grant
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D049109:Cell Proliferation; D064987:Cell- and Tissue-Based Therapy; D003287:Contrast Media / Q000737:chemistry; D052203:Ferrosoferric Oxide / Q000737:chemistry; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D045164:Mesenchymal Stem Cell Transplantation; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000000981:diagnostic imaging*; D011859:Radiography; D051381:Rats; D020521:Stroke / Q000175:diagnosis / Q000628:therapy*
chemical_list: D003287:Contrast Media; D052203:Ferrosoferric Oxide