title: Thiolated polyacrylic acid-modified iron oxide nanoparticles for in vitro labeling and MRI of stem cells.
abstract: OBJECTIVE
  The purpose of this study was to develop and characterize new surface-modified iron oxide nanoparticles demonstrating the efficiency to be internalized by human endothelial progenitor cells (EPCs) from umbilical cord blood.
  
  
  METHODS
  Iron oxide nanoparticles were coated with polyacrylic acid-cysteine (PAA-Cys) by either in situ precipitation or postsynthesis. The nanoparticles were characterized by X-ray powder diffraction. EPCs were labeled with PAA-Cys-modified iron oxide nanoparticles or with uncoated nanoparticles. The relaxivity of uncoated and coated iron oxide nanoparticles as well as EPCs labeled with PAA-Cys-modified iron oxide were determined.
  
  
  RESULTS
  Addition of PAA-Cys increased the particle size from 10.4 to 144 and 197 nm, respectively. The X-ray powder diffraction pattern revealed that the particles consist of Fe(3)O(4) with a spinal structure. Postsynthesis coated particles showed a cellular uptake of 85% and 15.26 pg iron/cell. For both types of particles the relaxivity ratio was at least 2-fold higher than that of the gold standard Resovist(®).
  
  
  CONCLUSIONS
  The PAA-Cys coated iron oxide nanoparticles are a promising tool for labeling living cells such as stem cells for diagnostic and therapeutic application in cell-based therapies due to their high relaxivities and their easy uptake by cells.
authors.affiliation: Department of Pharmaceutical Technology, Institute of Pharmacy, Leopold-Franzens-University Innsbruck, Innsbruck, Austria.
authors.forename: A
authors.initials: A
authors.lastname: Vetter
authors.forename: A
authors.initials: A
authors.lastname: Reinisch
authors.forename: D
authors.initials: D
authors.lastname: Strunk
authors.forename: C
authors.initials: C
authors.lastname: Kremser
authors.forename: H W
authors.initials: HW
authors.lastname: Hahn
authors.forename: C W
authors.initials: CW
authors.lastname: Huck
authors.forename: T
authors.initials: T
authors.lastname: Ostermann
authors.forename: K
authors.initials: K
authors.lastname: Leithner
authors.forename: A
authors.initials: A
authors.lastname: Bernkop-Schnürch
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D002478:Cells, Cultured; D005290:Ferric Compounds / Q000737:chemistry*; D006801:Humans; D008279:Magnetic Resonance Imaging; D053768:Metal Nanoparticles; D033362:Powder Diffraction; D017550:Spectroscopy, Fourier Transform Infrared; D013438:Sulfhydryl Compounds / Q000737:chemistry*
chemical_list: D000180:Acrylic Resins; D005290:Ferric Compounds; D013438:Sulfhydryl Compounds; C000499:ferric oxide; C006903:carbopol 940