title: Use of MR cell tracking to evaluate targeting of glial precursor cells to inflammatory tissue by exploiting the very late antigen-4 docking receptor.
abstract: OBJECTIVE
  To determine if glial precursor cells can be targeted to inflamed brain through overexpression of very late antigen-4 (VLA-4) and whether this docking process can be monitored with magnetic resonance (MR) cell tracking after intraarterial injection.
  
  
  METHODS
  All experimental procedures were performed between August 2010 and February 2012 and were approved by the institutional animal care and use committee. Human glial precursor cells (hGPs) were transfected with VLA-4 and labeled with superparamagnetic iron oxide that contained rhodamine. A microfluidic adhesion assay was used for assessing VLA-4 receptor-mediated cell docking in vitro. A rat model of global lipopolysaccharide (LPS)-mediated brain inflammation was used to induce global vascular cell adhesion molecule-1 (VCAM-1) expression. hGPs were infused into the carotid artery in four animal cohorts (consisting of three rats each): rats that received VLA-4-naive hGPs but did not receive LPS, rats that received VLA-4-expressing hGPs but not LPS, rats that received VLA-4-naive hGPs and LPS, and rats that received VLA-4-expressing hGPs and LPS. MR imaging was performed at 9.4 T before and 1, 10, 20, and 30 minutes after injection. Brain tissue was processed for histologic examination. Quantification of low-signal-intensity pixels was performed with pixel-by-pixel analysis for MR images obtained before and after cell injection.
  
  
  RESULTS
  With use of the microfluidic adhesion assay, cell binding to activated brain endothelium significantly increased compared with VLA-4-naive control cells (71.5 cells per field of view±11.7 vs 36.4 cells per field of view±3.3, respectively; P<.05). Real-time quantitative in vivo MR cell tracking revealed that VLA-4-expressing cells docked exclusively within the vascular bed of the ipsilateral carotid artery and that VLA-4-expressing cells exhibited significantly enhanced homing as compared with VLA-4-naive cells (1448 significant pixels±366.5 vs 113.3 significant pixels±19.88, respectively; P<.05). Furthermore, MR cell tracking was crucial for correct cell delivery and proper ligation of specific arteries.
  
  
  CONCLUSIONS
  Targeted intraarterial delivery and homing of VLA-4-expressing hGPs to inflamed endothelium is feasible and can be monitored in real time by using MR imaging in a quantitative, dynamic manner.
authors.affiliation: Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Cellular Imaging Section and Vascular Biology Program, Institute for Cell Engineering, The Johns Hopkins University School of Medicine, 733 N Broadway, Broadway Research Building, Room 649, Baltimore, MD 21205, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Gorelik
authors.forename: Inema
authors.initials: I
authors.lastname: Orukari
authors.forename: Joanne
authors.initials: J
authors.lastname: Wang
authors.forename: Shashikala
authors.initials: S
authors.lastname: Galpoththawela
authors.forename: Heechul
authors.initials: H
authors.lastname: Kim
authors.forename: Michael
authors.initials: M
authors.lastname: Levy
authors.forename: Assaf A
authors.initials: AA
authors.lastname: Gilad
authors.forename: Amnon
authors.initials: A
authors.lastname: Bar-Shir
authors.forename: Douglas A
authors.initials: DA
authors.lastname: Kerr
authors.forename: Andre
authors.initials: A
authors.lastname: Levchenko
authors.forename: Jeff W M
authors.initials: JW
authors.lastname: Bulte
authors.forename: Piotr
authors.initials: P
authors.lastname: Walczak
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001921:Brain / Q000166:cytology / Q000378:metabolism*; D002339:Carotid Arteries; D002448:Cell Adhesion; D058948:Cell Tracking / Q000379:methods*; D003287:Contrast Media / Q000494:pharmacology; D003911:Dextrans / Q000494:pharmacology; D015870:Gene Expression; D006801:Humans; D007091:Image Processing, Computer-Assisted; D039041:Integrin alpha4beta1 / Q000235:genetics / Q000378:metabolism*; D008070:Lipopolysaccharides; D008279:Magnetic Resonance Imaging / Q000379:methods*; D058185:Magnetite Nanoparticles; D044085:Microfluidics; D008856:Microscopy, Fluorescence; D009457:Neuroglia / Q000378:metabolism*; D051381:Rats; D016029:Receptors, Very Late Antigen / Q000235:genetics / Q000378:metabolism*; D012235:Rhodamines / Q000494:pharmacology; D014162:Transfection; D019010:Vascular Cell Adhesion Molecule-1 / Q000378:metabolism
chemical_list: D003287:Contrast Media; D003911:Dextrans; D039041:Integrin alpha4beta1; D008070:Lipopolysaccharides; D058185:Magnetite Nanoparticles; D016029:Receptors, Very Late Antigen; D012235:Rhodamines; D019010:Vascular Cell Adhesion Molecule-1; C065507:ferumoxides